# Hypothetical Jr Comp Dragster



## kennybobby (Aug 10, 2012)

[EDIT 1/8/2018]

Index of calculation results:

An aero and friction power load chart is found in post #152. 

A chart showing aero and friction effect on ET and speed for 700lbs and 3.3GR is found in post #161.

------------------------------------------------------
Initial post
We need some performance requirements:
Is this a 1/8 mile or 1/4 mile run? Answer: 1/8 mile = 660 ft
How quickly do you want to run, what is your target ET? Answer: min ET = 6.9 sec
Is there a maximum speed limit for this class? Answer: 110 mph
Do you want to include a cooling system or do without? He wants one.

We will get the answers from the previous thread:
Drag racing is about E.T. not mph. Jr Comp cars are restricted to 6.90 seconds or slower based on either an e.t. dial-your own
or heads-up basis; breakout rules apply. In qualified events, no racer can
qualify quicker than 6.900. Any racer running faster than 110.00 mph at any time
during an event is disqualified.
Most Jr Comp cars weigh 550 - 600 lbs. plus driver.
Calculate E.T.: 755 pounds and HP of 114 (85 kW)

[edit]

Constants and Constraints:
race distance: 1/8 mile = 660 ft
max speed: 110 mph = 161.3 ft/sec
minimum ET: 6.9 sec
tire diameter: 22" , Circumference = 5.76 ft
weight: 755 lbs; Mass = 23.4472 lb-sec^2/ft
pulley ratio: 10:3
YASA 400 motor torque at 450A: T~360 N-m = 265 ft-lbs up to 3000 RPM at 500V


Preliminary Calculatus Eliminatus:
Acceleration based on ET(min) and distance from x = .5 A t^2 ;
A = 27.72 ft/s2 = 0.86 g
Velocity from A and ET(min): v = At = 191.3 ft/sec = 130 mph exceeds max speed limit, therefore too high.
Acceleration based upon V(max) speed and ET(min):
A = v/t = 23.38 = 0.726 g

Power based upon Force and speed:
P = M A V(max) = 88405 lb-ft/sec = 161 HP

Energy of mass at V(max) from 1/2 M V^2:
E = 304956 lb-ft

Energy of pack: 500V at 500A
E = 250000 kW

Average Power from Energy over ET(min):
P = dE/dT = 44197 lb-ft/sec = 80.4 HP

Bottoms-Up Look:
Need 548 Lbsf to accelerate and meet 6.9 sec ET and not break out Vmax

Torque at axle = r x F = 11/12 * 548 = 502.5 ft-lbs * 3/10 pulley ratio = 150 ft-lbs at motor
And current will be 150/285 * 450A = 238 Amps, easily provided by the 500V/500A pack. 
This is all without aero, friction and other losses.

So the pack and motor size appear to have a good margin to meet the requirements with some margin for losses.


----------



## kennybobby (Aug 10, 2012)

Using 6.9 sec for 1/8 mile run is consistent with your sizing of the motor power and gear ratio for the vehicle weight. The 85kW at 450 Amps would only require 188 Volts, so the 200 V pack might be plenty, but the back emf of the 400 motor is about 165 V/krpm and you will need 3krpm, so that gets you to 500 Volts for the battery pack. 

So the cooling answer depends if this motor can survive 6.9 seconds at 450 Amps. The graphs are for operation with coolant at 65C. That's where a decent motor datasheet would list the winding resistance or a thermal time constant--to determine how long it can run at peak torque. Usually the peak torque rating is for 5 or 10 seconds of operation, which would be great in this situation meaning no cooling required.

i wonder if they could make a custom winding for you, larger gauge wire to lower the resistance and reduce the voltage and also allow an increase in current.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> We need some performance requirements:
> 
> Is this a 1/8 mile or 1/4 mile run?
> 
> ...


1/8th mile.
Target ET is 6.9 sec.
The motor has a liquid cooling system but no radiator.
Maximum driver age is 19 years.

Estimated weight
rolling chassis 460 lb 
Yasa 400 motor 55 lb 
battery 60 lb(500V)Lone Star Sleeper Cells 
cable electronics 40 lb 
615 lb 
driver 140 lb 
*755 lb. *


----------



## tropes (Jul 24, 2011)




----------



## tropes (Jul 24, 2011)

The weight is based on a Mcgee Cams Jr Comp car with a Suzuki engine. I will ask John Metric the weight of his Sleeper cells. Most Jr Comp drivers are former Junior Dragster drivers. Our last driver weighed 95 lbs. The electronics weight is just a WAG. The attraction of the Yasa 400 is the weight and physical dimensions- 4" wide which eliminates the need for a jackshaft and narrows the rear axle. The rule on brakes is difficult to define: "Two rear-wheel hydraulic disc brakes mandatory. With a total car weight of 1,000 pounds or less, and a one-piece rear axle, may use a single brake rotor with dual calipers."
Minimum tire diameter is 20" but I chose 22" because neither Hoosier or M&H make a wide enough 20" (I will stand corrected).

Top/Bottom View:


----------



## Frank (Dec 6, 2008)

IIRC the 6S sleeper cells are about 2#/brick ~ 1kg/brick. I'm sure you know there's lots of brushed-DC motor solutions that would be a lot more economical than the PM approach. Which "other" thread are you referring to?

thx
Frank


----------



## tropes (Jul 24, 2011)

Frank said:


> IIRC the 6S sleeper cells are about 2#/brick ~ 1kg/brick. I'm sure you know there's lots of brushed-DC motor solutions that would be a lot more economical than the PM approach. Which "other" thread are you referring to?
> 
> thx
> Frank


Thank you Frank.
I have asked John to join the conversation re his sleeper cells.
Yes, as you know I have had some experience with series wound brushed DC motors.
The attraction of the Axial Flux PM motor is the weight and physical dimensions- 4" wide which eliminates the need for a jackshaft and narrows the rear axle.
The other thread is in Controllers Forum - Axial flux motor dragster.
tropes


----------



## brian_ (Feb 7, 2017)

Seeing the two-stage belt drive in the previous thread, I wondered if you might take advantage of the narrow width of the "pancake" Yasa motor to simplify that to a single stage... and you did. The narrow motor makes the packaging work, and the reduction ratio needed for the relatively high-torque and low-speed motor can be reached in one stage. Looks good!


----------



## brian_ (Feb 7, 2017)

If you can use up to 7500 rpm, with the maximum allowed trap speed of 110 mph corresponding to 1680 rpm at the axle with 22" tires (not accounting for tire growth with speed), then you could use up a drive ratio up to 4.4:1. It may be that a greater ratio is not mechanically practical, due to the minimum size of the motor pulley (to maintain at least the minimum bend radius for the belt) or the maximum size of the axle pulley (for component clearance or other factors)... I'm sure that's already been considered. 

There's no need to go with more reduction if you can't use the drive force (due to limited traction), and even with the 3.33:1 reduction you may need to set a lower current limit to prevent wheelspin (assuming that you want to electronically control that rather than depending on the driver's control of the accelerator pedal).

I didn't see a link to the motor: it appears to be the YASA-400 (datasheet)

At 500 volts, the constant-torque range ends at 3000 rpm motor speed, which would be 900 rpm axle speed with this gearing, and 59 mph with the 22" tires... well down the 1/8 mile, but not to the end so the run would finish in the constant-power zone.

If the tires have enough traction to use all 360 lb-ft of drive torque at low speed, that would be 1309 lb of forward thrust (with 22" tires, assuming 11" loaded radius and no losses in the belt drive or tires). That's 1.73 g of acceleration (assuming 755 lb total weight), so 59 mph would come up in only 1.55 seconds after about 20 metre or 48 feet, without rolling or aerodynamic drag. Due to drag it will take longer and cover more of the track... perhaps roughly around the 60-ft mark (reached in 1.633 seconds by Terry in a timing slip that he posted for his "golf cart" drag racer at Ozark). If you have the traction to handle the thrust, this is looking good for a Jr. Comp run.

To finish the 1/8 mile, another 4.2 seconds of constant-power acceleration at 85 kW (well under peak power for 500 volts, but above the cooling-limited continuous power), minus a wild guess of 15 kW (average over the speed range) for drag, adds about 280 kJ of kinetic energy to the 116 kJ of energy at 26 m/s (59 mph), to reach 48 m/s or 107 mph. Calculating the distance covered to see if the 1/8 mile is reached in this time is past my one-line-on-the-calculator-on-Sunday-afternoon level, but it looks promising... it's faster than Terry's time for the 1/8th.

If anyone remembers the link for the online calculator (as I mentioned in the other thread) which produces acceleration given various motor and car characteristics, the data could be plugged into that to predict performance. Both aero drag and rolling drag will be pretty rough guesses, unless someone has suitable data - drag slicks are way off of average tires, and dragsters are way off of typical cars.


----------



## brian_ (Feb 7, 2017)

tropes said:


> The motor has a liquid cooling system but no radiator.


I assume that this will mean a coolant reservoir and a circulation pump. The coolant is oil; the flow rate would presumably be the 12 litres/minute specified by YASA. With only a few seconds of operating time under load and only 0.2 L/s of flow, the oil will get only one pass through the motor so essentially the motor inlet will always be getting cool oil.

The coolant temperature will rise to absorb the heat generated; if the motor uses 100 kW average and puts 15% of that into the coolant as heat, that's about 15 kW of heating. If the heat capacity of the oil is about 2 kJ/kg-K, or 1.5 kJ/L-K, that flow rate can absorb 0.3 kW per degree K of temperature rise... suggesting a 50 K temperature rise. The motor is spec'd for 65 °C inlet, so if the oil starts at "room temperature", it will still be almost cool enough to feed right back in the inlet, even after coming out of the outlet after one pass. Add a couple litres of oil capacity, in a metal tank that acts as a slow radiator, and it seems like there should be margin for warm days and repeated runs.


----------



## brian_ (Feb 7, 2017)

From the earlier topic, but still relevant:


tropes said:


> ... Perhaps the back EMF could be used for regen since this is concern I have. Without a clutch towing would cause the motor to become a generator.


The motor can freewheel, and will if the controller is not trying to regenerate. 

You could deliberately use this as a way to get a head-start on recharging while towing back after a run, but my guess is that it would be better to just let the battery cool a bit first. Some regenerative braking could certainly be used to slow down after completing a run, reducing mechanical brake heating and wear.


----------



## tropes (Jul 24, 2011)

brian_ said:


> The motor can freewheel, and will if the controller is not trying to regenerate.


Before digesting your valuable information allow me a nostalgic moment.
A 40year quest.








I can assemble a 1350 cfm Holley with my eyes closed but have some trouble with electronics.


----------



## kennybobby (Aug 10, 2012)

brian_ said:


> ...
> If the tires have enough traction to use all 360 lb-ft of drive torque at low speed, that ...


The units for torque on the datasheet were in N-m.

torque is a vector cross product = r x F, and the units are ft-lbs. Lb-ft is an energy unit, just to avoid confusion. The SI units should be m-N to be consistent with the math definition, but they do it wrong and i don't care to try to get them to change...


----------



## major (Apr 4, 2008)

kennybobby said:


> torque is a vector cross product = r x F, and the units are ft-lbs. Lb-ft is an energy unit, just to avoid confusion. The SI units should be m-N to be consistent with the math definition, but they do it wrong and i don't care to try to get them to change...


The proper Imperial unit for torque is the pound foot or lb.ft., where it is assumed that it is a pound force and need not be abbreviated lbf.ft. The energy unit is foot pound or ft.lb.

In S.I. units I've never seen the meter Newton (mN) used. Nm is used for torque and sometimes for energy or work although the Joule is the common unit for energy.

Even though torque and energy basically have the same units, they are different physical quantities and cannot be equated.

It is easy to find references to support either ft.lb. or lb.ft. for either. I've stated the convention I've seen used in academia and industry for 4 or 5 decades. Really not worth an argument.

Regards,

major


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> The units for torque on the datasheet were in N-m.


Yes, as they should be.  I consistently use pound-feet for torque, for consistency with the SI unit and distinction from the energy units. While I agree with major that it is not very important, anyone interested in standard usage might want to consult the Guide for the Use of the International System of Units (SI) from the U.S. National Institute for Standards and Technology. They are not the world's only authority on this, but I note that newton-metres is the usage consistently followed for torque in the automotive industry and every other area that I have seen.

This does mean that both energy and torque (or moment) have the same units... but that's not unusual. There are many cases where two different physical quantities are dimensionally equivalent. If "lb-ft" means energy to you, while "ft-lb" means torque, then you need to consider the context. This is not like the novice problem of confusing power and energy units (or the scam artists practice of deliberately convoluting them).

And yes, pound of force (rather than pound of mass) is implied by context. The stupidity of the pound-slug-poundal mess of force and mass units is hopeless, and context must always be considered when "pound" is used.


----------



## tropes (Jul 24, 2011)

Back to my level. If the center of the rear axle is less than a foot away from the circumference of the tire, do I measure a gain in torque?
Radius of the tire is less than a foot (11 inches).


----------



## tropes (Jul 24, 2011)

Rear Axle Parts


----------



## tropes (Jul 24, 2011)

Gates Poly Chain Belt


----------



## tropes (Jul 24, 2011)

brian_ said:


> I assume that this will mean a coolant reservoir and a circulation pump. The coolant is oil; the flow rate would presumably be the 12 litres/minute specified by YASA. With only a few seconds of operating time under load and only 0.2 L/s of flow, the oil will get only one pass through the motor so essentially the motor inlet will always be getting cool oil.


I was hoping to use antifreeze and a small expansion tank. Little heat is generated in 8 seconds.


----------



## Karter2 (Nov 17, 2011)

The torque on the wheel is the same as the torque at the axle , which is the same as the torque at the axle driven sprocket..
What changes is the resulting FORCE at the tyre circumference which will vary with the tyre diameter.
Torque = Force x Radius.


----------



## tropes (Jul 24, 2011)

Karter2 said:


> The torque on the wheel is the same as the torque at the axle , which is the same as the torque at the axle driven sprocket..
> What changes is the resulting FORCE at the tyre circumference which will vary with the tyre diameter.
> Torque = Force x Radius.


Thanks Karter2. So distance per revolution is lost but force is gained. Is that correct?


----------



## brian_ (Feb 7, 2017)

tropes said:


> Back to my level. If the center of the rear axle is less than a foot away from the circumference of the tire, do I measure a gain in torque?
> Radius of the tire is less than a foot (11 inches).


As karter2 explained, you don't gain torque, but with a smaller tire (shorter lever arm) the force must be higher for the torque to be the same.



tropes said:


> So distance per revolution is lost but force is gained. Is that correct?


With a smaller tire, yes. 

Changes in gearing or tire size can't make or destroy power, so if the same power is giving you more pushing force, it must be at lower speed:

power = torque x rotational speed (so when you go through gearing or belt drives, where there's more torque there's less shaft speed), and 
power = force x speed (so if you change tire size or any other lever, the force at the end of shorter lever or at the tread of the shorter tire is higher but the speed along the ground is slower)


----------



## tropes (Jul 24, 2011)

brian_ said:


> With a smaller tire, yes.
> 
> 
> 
> ...


Got it. Still no inverter/controller suggestions. Perhaps more motor info is needed.


----------



## brian_ (Feb 7, 2017)

tropes said:


> I was hoping to use antifreeze...


The motor specs that I saw say oil.

Water is a better heat transfer fluid, and a water/glycol coolant mixture is also better than oil... so no one uses oil to cool if they have a choice. There have been engines with heads cooled by the engine oil, because the designer needs better cooling than just air, but still wants to avoid a separate cooling system... but no one builds an engine with an oil-filled system just as a coolant.

My guess is that YASA wants oil in the motor either because they want it to be non-conductive, or they want it to be non-corrosive to the materials used. I suggest checking with them before planning to touch the motor with anything water-based.

If you can use water, you don't need antifreeze... assuming that you are completely draining it before letting it freeze (no Christmas race in Alberta ). Glycol both lowers the freezing point and raises the boiling point, but it decreases heat capacity (how much heat a given volume of coolant absorbs per degree of temperature rise) and lowers the rate of heat transfer. Race-only cars routinely use no antifreeze, and some drag racers use no coolant at all (not likely a good option in this case). For those using water without glycol antifreeze, and wanting to reuce corrosion and improve performance, there are additives (such as Redline WaterWetter), and pre-mixed (but mostly water) coolant such as the one from Summit.


----------



## Frank (Dec 6, 2008)

If the Yasa is like the Remy, oil also lubricates the bearings. Not much heat is generated in 1/8-mile. Another issue to be aware of is adequate chain or belt wrap around the drive sprocket. There turns out to be a minimum recommended distance between axles as a function of sprocket size (IIRC) to account for this. 

I'm pretty sure that Rinehart supports the Yasa (see their site) and with a well-prepped strip I doubt you'd have wheelspin issues.


----------



## kennybobby (Aug 10, 2012)

My point was lost.

The datasheet was 360 N-m, not ft-lbs...so the calculations are not correct.


Controller question:

How is this motor commutated? Typically PM motors have some sort of feedback sensor of rotor angle--hall sensors, encoder, resolver. A tachometer is nice to measure speed.


----------



## major (Apr 4, 2008)

KB,
I don't think your point was missed. Perhaps you missed ours. The first reference provided by brian_ confirms my take on lb ft.

Tropes,
Regarding the electronics (motor controller): It is difficult to do. Few can do it. And typically they are well paid for it. DIY-ers can be found occasionally like on endless-sphere.com. Look at lebowski controller and efforts of Arlo1. He recently exceeded 300 HP on a dyno-ed Leaf motor with his prototype.

In general, it is a mistake to tie down the motor type and design this early in the process, unless you own stock in the motor company. Your best machine will result from the most degrees of freedom. The rulebook and mother nature impose enough design constraints.

When attempting to optimise performance on paper, so to speak, I have thought there could be derived a mathematical expression for ET as a function of GR. This could be solved for a minimum using calculus. Any math majors out there?

Regards,

major


----------



## Frank (Dec 6, 2008)

major said:


> I have thought there could be derived a mathematical expression for ET as a function of GR.


As long as the discussion doesn't digress into the torque-versus-power one, lol.


----------



## tropes (Jul 24, 2011)

major said:


> KB,
> Tropes,
> Regarding the electronics (motor controller): It is difficult to do. Few can do it. And typically they are well paid for it. DIY-ers can be found occasionally like on endless-sphere.com. Look at lebowski controller and efforts of Arlo1. He recently exceeded 300 HP on a dyno-ed Leaf motor with his prototype.
> 
> ...


I agree but I have seen few motors that have the physical dimensions that allow direct drive to driven and a narrow rear axle.










The basics for an Inverter/controller. Feel free to comment.
tropes


----------



## tropes (Jul 24, 2011)

Frank said:


> If the Yasa is like the Remy, oil also lubricates the bearings. Not much heat is generated in 1/8-mile. Another issue to be aware of is adequate chain or belt wrap around the drive sprocket. There turns out to be a minimum recommended distance between axles as a function of sprocket size (IIRC) to account for this.


I just saw a YouTube video of a Yasa without coolant being tested with 96V for 20 seconds. This seems to indicate that the oil does not lubricate the bearings.
Yes there is a recommended distance to ensure enough teeth are contacting the belt. I used Gates Poly Chain belt on my Junior Dragster with a 28 tooth drive and a 114 tooth driven sprocket 14" C-C for 5 years without any problem. The recommended sprocket sizes and C-C distance charts are available from Gates and Pfeifer Industries who built my sprockets.


----------



## tropes (Jul 24, 2011)

Possible gear ratio sprocket teeth combinations:
*DRIVE*... *DRIVEN* ...*RATIO*
__30_____100_____3.33: 1
__32_____ 100____ 3.125:1
__30_____ 98 _____3.27:1


----------



## John Metric (Feb 26, 2009)

tropes said:


>


Very cool, I will bring this up to the NHRA during the PRI safety conferences this week.


----------



## tropes (Jul 24, 2011)

John Metric said:


> Very cool, I will bring this up to the NHRA during the PRI safety conferences this week.


Good. The sanctioning bodies NHRA and IHRA must realize that with the increasing number of EV production there will come a time to include them in their classifications.

Could you give the weight of a Sleeper Cell battery that would meet the requirements of the Yasa motor 500V 500A to the motor assuming 95% efficiency. We have not yet determined what inverter/controller will be used.
Thanks
tropes


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> The datasheet was 360 N-m, not ft-lbs...so the calculations are not correct.


Now I see that I did say if all 360 _lb-ft_ of torque can be used, not all 360 _Nm_: that's just a typo. Not sure why you didn't say that, instead of commenting about torque versus energy units and standards of practice for units of measurement. 

My calculations - in contrast - were all done in SI, converting into and out of SI units as required to accommodate input data and an assumption that lb/ft/mph results would be preferred. If I missed anything in any of them - that happens - please let me know.


----------



## brian_ (Feb 7, 2017)

Frank said:


> If the Yasa is like the Remy, oil also lubricates the bearings.


Now *that* would be an excellent reason to use oil! 



Frank said:


> Another issue to be aware of is adequate chain or belt wrap around the drive sprocket. There turns out to be a minimum recommended distance between axles as a function of sprocket size (IIRC) to account for this.


I assume that the design tools offered by the belt manufacturers would consider this, and it looks like tropes already worked through those tools.



Frank said:


> ... with a well-prepped strip I doubt you'd have wheelspin issues.


Good to know.  Of course higher classes of drag racers manage even higher accelerations, so the traction is there if suitably equipped, but details vary between classes. My motorsport experience is in autoslalom, rally, and road race... and they all run on real road surfaces rather than drag strips, so available traction is different (no one does 2 g anywhere but a drag strip without substantial aero downforce).


----------



## brian_ (Feb 7, 2017)

major said:


> When attempting to optimise performance on paper, so to speak, I have thought there could be derived a mathematical expression for ET as a function of GR. This could be solved for a minimum using calculus. Any math majors out there?


It would be reasonably straightforward if the same constraints applied throughout the run, but in practice the beginning is at relatively constant acceleration or thrust force, limited by motor torque or tire traction, then the rest is ideally limited by constant power.

For the constant acceleration portion, the usual
velocity = acceleration x time
and
distance = 1/2 x acceleration x time squared (the result of integrating velocity over time)
and rearrangements of those do everything needed. With acceleration proportional to force, which is proportional to wheel torque, which is proportional to gear ratio, all formulas can be expressed as functions of the ratio.

For the constant power portion, the idea to predict performance would be to integrate acceleration (which varies in inverse proportion to speed because force x speed is the constant) over time to get velocity, and over time again to get distance. It's too late at night for me to do that calculus, but the bigger problem is that the expression to be integrated should also include terms to account for drag.

The gear ratio (along with motor characteristics as limited by the power supply) will determine the amount of torque available at the wheels, for the constant acceleration portion. It has no effect on the constant power portion (except determining the transition point from constant torque to constant power), if the motor has this ideal characteristic (and PM AC motors are not far off that).

All of this (including applying a specified gear ratio) is done numerically (rather than analytically) by available simulation software... which is why I would like to find the perfectly good example which I have previously seen in this forum. The simulation can just be run for a range of gear ratios, which is the most practical way to evaluate the effect of the ratio.


----------



## tropes (Jul 24, 2011)

brian_ said:


> All of this (including applying a specified gear ratio) is done numerically (rather than analytically) by available simulation software... which is why I would like to find the perfectly good example which I have previously seen in this forum. The simulation can just be run for a range of gear ratios, which is the most practical way to evaluate the effect of the ratio.


Considering the time of day, you're not doing badly.
John Metric is a data freak. Perhaps he knows of this "perfectly good example".

tropes


----------



## tropes (Jul 24, 2011)

I received this response from www.PandSPowerElectronics.com last week regarding the possibility of acquiring a suitable controller. Hopefully, we can get some feedback on this.

_"I just finished a control board that is a drop in replacement for the chevy volt inverter's controls. That inverter has basically 2 separate 111kW inverters inside. They can be run in parallel for over 200kW of a single motor, or independently to power 2 separate motors. It is liquid cooled and maybe weighs around 15 pounds, and is about the same size as what I would make (it's very compact). I"m going to solder a prototype board hopefully this weekend for it and test it out. I"m pretty sure I got the pinout to the driver section right, but it's nothing like testing it. I have a nissan leaf motor here I'll test it out on." _

tropes


----------



## kennybobby (Aug 10, 2012)

That inverter sounds just like what you need to drive that motor.

Did you ever find out how commutation is done for the Yasa motor--does it use hall sensors to determine rotor position, or some other method?


----------



## dain254 (Oct 8, 2015)

I could be wrong, but in this application I think a person would be nuts to use anything but a roller chain for the final drive reduction- noise is the primary reason for using a belt drive on an EV, but they are slightly less efficient than a good old fashioned chain. THE MAJOR benefit of the roller chain is the ability to add/remove links and change gear ratios easily/cheaply! A person can calculate and scheme all they want and arrive on that perfect theoretical ratio for their belt drive (or 2 or 3 ratios - $$$)... but once you've spent the money and hit the track, now you are locked into your theoretical ideal scenario, where I've got my box of sprockets/counter sprockets that allow me to compensate for the 15mph headwind or tailwind that particular day, or lead weight I'm forced to carry because my car is 50lbs light by the track scales... all hypothetical!


----------



## tropes (Jul 24, 2011)

kennybobby said:


> That inverter sounds just like what you need to drive that motor.
> 
> Did you ever find out how commutation is done for the Yasa motor--does it use hall sensors to determine rotor position, or some other method?


I asked Paul at P&S and received this reply.
_"The Yasa I tested had sin/cos inputs to the microcontroller. So, they were waveforms that were centered around 2.5v, and went up about 1.5v and down about 1.5v, so you do an A/D conversion on the 2 signals to measure the position."_
tropes


----------



## tropes (Jul 24, 2011)

dain254 said:


> I could be wrong, but in this application I think a person would be nuts to use anything but a roller chain for the final drive reduction- noise is the primary reason for using a belt drive on an EV, but they are slightly less efficient than a good old fashioned chain. THE MAJOR benefit of the roller chain is the ability to add/remove links and change gear ratios easily/cheaply! A person can calculate and scheme all they want and arrive on that perfect theoretical ratio for their belt drive (or 2 or 3 ratios - $$$)... but once you've spent the money and hit the track, now you are locked into your theoretical ideal scenario, where I've got my box of sprockets/counter sprockets that allow me to compensate for the 15mph headwind or tailwind that particular day, or lead weight I'm forced to carry because my car is 50lbs light by the track scales... all hypothetical!


Thanks for your input dain254. Where can we find an Efficiency Comparison between Belt and Chain?
On what EV are you using the chain drive?

tropes


----------



## tropes (Jul 24, 2011)

Frank said:


> Another issue to be aware of is adequate chain or belt wrap around the drive sprocket. There turns out to be a minimum recommended distance between axles as a function of sprocket size (IIRC) to account for this.


I went back into the data from RCD Engineering Inc. and Gates and found that the maximum C-C distance using the Poly Chain Carbon belt was 14 inches without using a belt tensioner pulley. I then used the Pfeifer chart using 12.5" C-C to determine the greatest number of Teeth In Mesh with several combinations of Drive and Driven sprockets. With gear ratios between 3.27:1 and 3.40:1 the TIM was the same. To get an extra tooth in mesh the gear ratio would be 3.125:1 which is a 32 tooth Drive and a 100 tooth Driven.


----------



## tropes (Jul 24, 2011)

Frank said:


> IIRC the 6S sleeper cells are about 2#/brick ~ 1kg/brick. thx
> Frank











tropes


----------



## tropes (Jul 24, 2011)

brian_ said:


> Of course higher classes of drag racers manage even higher accelerations, so the traction is there if suitably equipped, but details vary between classes. My motorsport experience is in autoslalom, rally, and road race... and they all run on real road surfaces rather than drag strips, so available traction is different (no one does 2 g anywhere but a drag strip without substantial aero downforce).


 
A well prepped track is a factor contributing to initial traction and wheel spin. Aerodynamic downforce comes into play after speed is reached.
Important controlled factors are tires and tire air pressure. Some tire spin is necessary but initially forward movement is delayed by the wadding up of the wrinkle wall tire. If air pressure of the tire is too high there is tire spin ; if too low there is bouncing or chatter effect. 
Interestingly, there is a reduction of the radius of the tire. https://www.youtube.com/watch?v=iQdlAfrL-dA


----------



## Batterypoweredtoad (Feb 5, 2008)

Does this class favor consistency over lowest ET? It seems like the ability to control ramp speed and eliminate the uncertainty of wheelspin would be a gigantic advantage in that situation.


----------



## tropes (Jul 24, 2011)

Batterypoweredtoad said:


> Does this class favor consistency over lowest ET? It seems like the ability to control ramp speed and eliminate the uncertainty of wheelspin would be a gigantic advantage in that situation.


Definitely consistency. 
NHRA Rule: 
E.T. Restrictions
Dial-in restricted to 6.90 seconds or slower based on either an e.t. dial-yourown
or heads-up basis; breakout rules apply. In qualified events, no racer can
qualify quicker than 6.900.
Any racer running quicker than 6.70 or faster than 110.00 mph at any time
during an event will be disqualified from the event.

tropes


----------



## Batterypoweredtoad (Feb 5, 2008)

Do you win by getting closer to your dial in time than the person you are running down the strip with?


----------



## tropes (Jul 24, 2011)

Batterypoweredtoad said:


> Do you win by getting closer to your dial in time than the person you are running down the strip with?


You win by getting to the finish line first, provided you don't red light or break out (go quicker than your dial-in).


----------



## tropes (Jul 24, 2011)

Batterypoweredtoad said:


> Do you win by getting closer to your dial in time than the person you are running down the strip with?


The Don Garlits Museum of Drag Racing is 45 minutes south of Gainesville. Worth a visit if you want to know more.
tropes


----------



## Batterypoweredtoad (Feb 5, 2008)

I know a casual amount about drag racing as an occasional spectator and even more occasional participant. I definitely don't have a complete knowledge of all the classes,the rules governing them, or the nuances to do the best in each. I was pretty sure you were building for a Bracket Racing class and wanted to clarify that.

My thought is that with the style of racing you are doing an electric should have a massive advantage over an ICE car. You don't have to shift, you don't you don't have to worry about a torque converter, etc. 

The main thing you have to worry about is a clean launch. My thought is if you focus less on the best possible launch and instead work on the most repeatable launch you eliminate most of the variables on the primary thing you have to control. 

I understand that this is probably all already being considered, but when I saw the conversations about the behavior of slicks during a full effort launch I thought I would mention the possibility of this approach just in case.


----------



## tropes (Jul 24, 2011)

Batterypoweredtoad said:


> I understand that this is probably all already being considered, but when I saw the conversations about the behavior of slicks during a full effort launch I thought I would mention the possibility of this approach just in case.


If you watch some of the videos on our website http://www.lightswitchracing.com/ you can see the advantage of an electric but the driver's skill is most important. 
BTW, we were asked to donate our junior to the Garlits Museum after it is retired.
tropes


----------



## tropes (Jul 24, 2011)

Batterypoweredtoad said:


> Do you win by getting closer to your dial in time than the person you are running down the strip with?


A great example of driver patience and skill. The other lane was dialled in at 18 seconds and we were dialled in at 9 seconds which gave a 9 second head start to the other lane. We won by .01 seconds due to driver reaction time. https://www.youtube.com/watch?v=yjZM6nuQkqk


----------



## piotrsko (Dec 9, 2007)

Yup. Back in the day there was a girl at LYONS in LA in a stocker toyota pickup that was unbeatable at 15 seconds. Cant tell you how many people would blow the launch after she was 3/4 of the way down the strip.


----------



## tropes (Jul 24, 2011)

John Metric said:


> Very cool, I will bring this up to the NHRA during the PRI safety conferences this week.


This is the NHRA Jr Comp rule:
*J**R**. C**OMP*
*Requirements and specifications for Jr. Comp vehicles are the*
*same as those for the NHRA **Summit** Racing Jr. Drag Racing*
*League with the following exceptions:*
*J/C, preceded by car number.*
*The class is conducted on the eighth-mile format.*
*Jr. Comp may not run against, or side by side with, any other Jr. Drag Racing*
*League category.*
*Age Requirements*
*Drivers may compete from the day of their 14th birthday through the year*
*of their 20th birthday. Driver must complete test runs and obtain a Jr. Drag*
*Racing League Jr. Comp competition license before participation.*
*Car and driver older than 16 may compete in appropriate E.T. category.*
*E.T. Restrictions*
*Dial-in restricted to 6.90 seconds or slower based on either an e.t. dial-yourown*
*or heads-up basis; breakout rules apply. In qualified events, no racer can*
*qualify quicker than 6.900.*
*All vehicles restricted to one four-stroke, OEM motorcycle, snowmobile,*
*personal watercraft, or industrial engine (nonautomotive), with a maximum of*
*four cylinders and a minimum of two cylinders. Must be NHRA accepted. Any*
*internal modifications permitted. Aftermarket cylinder heads permitted.*

If we add:
_"__MOTOR_
*All vehicles are restricted to a maximum of one (1) rear-mounted **nonautomotive** electric motor."*
an electric vehicle would be allowed.


----------



## John Metric (Feb 26, 2009)

Why limit it to one?
and why non-automotive?


----------



## tropes (Jul 24, 2011)

John Metric said:


> Why limit it to one?
> and why non-automotive?


1) One motor is all that is necessary. 
2) To be comparable to ICE rule. 
*All vehicles restricted to *one* four-stroke, OEM motorcycle, snowmobile,*
*personal watercraft, or industrial engine (nonautomotive), *

tropes


----------



## Frank (Dec 6, 2008)

Presently there are any displacement limits?


----------



## Frank (Dec 6, 2008)

That was supposed to be a question....


----------



## tropes (Jul 24, 2011)

Frank said:


> Presently there are any displacement limits?


No displacement limit but a maximum 4 cylinders and 6.9 ET or slower.

tropes


----------



## brian_ (Feb 7, 2017)

tropes said:


> All vehicles restricted to one four-stroke, OEM motorcycle, snowmobile, personal watercraft, or industrial engine (nonautomotive), with a maximum of four cylinders and a minimum of two cylinders. Must be NHRA accepted. Any internal modifications permitted. Aftermarket cylinder heads permitted.
> 
> If we add:
> "All vehicles are restricted to a maximum of one (1) rear-mounted electric motor."





John Metric said:


> Why limit it to one?


I have the same questions.



tropes said:


> 1) One motor is all that is necessary.


And with an engine, only one cylinder is necessary; for the same performance, only two (or maybe three if you don't work very hard at it) are necessary... and yet four are allowed. The rules don't exist to define the vehicle's design, or to optimize the design; they exist to limit competitors. Multiple engines may offer an advantage (likely just as a workaround to the rest of the engine rules) and so they are banned to both keep the cost down for competitors and to simplify the situation for regulators.

Unless multiple motors are an advantage, no one will run them. Unless there is a specific reason to ban multiple motors, there is no reason for the rule.

Formula E cars tend to have only one motor, but not by direct regulation: they are not allowed to direct a different amount of torque to each wheel, so functionally must use a differential, and deliver all power though one shaft, making more than one motor redundant. There needs to a functional reason for the rule...



John Metric said:


> and why non-automotive?





tropes said:


> 2) To be comparable to ICE rule...


I'm back to the reason for the existence of rules. If someone knows *why* NHRA decided to ban automotive engines, then it might be apparent what would be appropriate for electric motors. If simply copying the engine rule, then the electric version would be to require that the motor be of "OEM motorcycle, snowmobile, personal watercraft, or industrial" origin, which would make little sense.

Keep in mind that - assuming NHRA is like every other form of motorsport and most of society - the rule was probably the result of arguments based on the experience and commercial interests of some participants and their sponsors, so it probably makes only marginal technical sense.

The origin restriction plus cylinder count limit may have been a way to limit power, particularly since there is no displacement limit; the most powerful 4-cylinder bike engines run a couple hundred horsepower, while 4-cylinder automotive engines (in race trim) could be much larger and more powerful. To be a useful equivalent, the electric motor would need to be restricted in physical size, voltage, or current... origin seems to be unlikely to be relevant. If the proposed statement is the only electric motor rule, and there is no battery rule, there is effectively no regulatory limit on power output.

While not intending any offense to NHRA rule makers, the engine rule also appears to be badly flawed, since the inclusion of "OEM" for motorcycles implies that the other sources can be non-OEM... so I can put any engine I want in a snowmobile, christen it "My Snowmobile Engine", and it becomes legal for Jr. Comp Dragster.  I hope that a new electric motor rule would be better thought out.

And why the restriction to rear-mounted? There's no other sensible place to put it than roughly near the axle, and this definition would invite arguments about what "rear" means (I think rearward of driver is intended, but it doesn't say that).


----------



## tropes (Jul 24, 2011)

brian_ said:


> ...
> I'm back to the reason for the existence of rules. If someone knows *why* NHRA decided to ban automotive engines, then it might be apparent what would be appropriate for electric motors. If simply copying the engine rule, then the electric version would be to require that the motor be of "OEM motorcycle, snowmobile, personal watercraft, or industrial" origin, which would make little sense.
> 
> Keep in mind that - assuming NHRA is like every other form of motorsport and most of society - the rule was probably the result of arguments based on the experience and commercial interests of some participants and their sponsors, so it probably makes only marginal technical sense.
> ...


The precursor to the Jr. Comp rules is*:*
*Requirements and specifications for Jr. Comp vehicles are the*
*same as those for the NHRA **Summit** Racing Jr. Drag Racing*
*League with the following exceptions:*

As John Metric knows, I have for several years given thought to how to best approach NHRA regarding the inclusion of electric vehicles. Presently NHRA recognises only one class of EV's; Electric Junior Dragster. The same flaws exist in the NHRA Junior Dragster class with the same precursor for Electric Juniors.
My experience has led me to believe that the best approach is to "keep it simple". Therefore, I believe the best chance of being accepted is to add "electric motor" to their list of "badly flawed" engine requirements. Omitting their term "nonautomtive" may be contentious but that could be negotiated.


----------



## tropes (Jul 24, 2011)

My NHRA Rule Book is 2015. The term "nonautomotive" may have been changed.

tropes


----------



## kennybobby (Aug 10, 2012)

What is the typical weight of a chassis/roll cage structure? front wheel and tire? rear wheel and tire? etc.. just to get some ideas about distribution and weight budget.

Or maybe just a complete bare bones rolling chassis with adequate safety structure (cage and roll bar).

We have a 1/8 mile track nearby that has a test n tune night--i might want to build one of these things...


----------



## tropes (Jul 24, 2011)

Just checked the 2018 NHRA rule book; no change to the ENGINE rules.
However, I did find a possible reason for one engine:

*...vehicle must not be able to exceed 90 decibels as measured on the A scale
at 50 feet from the car while under acceleration
on the racetrack.
*(Facetious remark)


----------



## tropes (Jul 24, 2011)

kennybobby said:


> What is the typical weight of a chassis/roll cage structure? front wheel and tire? rear wheel and tire? etc.. just to get some ideas about distribution and weight budget.
> 
> Or maybe just a complete bare bones rolling chassis with adequate safety structure (cage and roll bar).
> 
> We have a 1/8 mile track nearby that has a test n tune night--i might want to build one of these things...


My estimated weights:

rolling chassis 460 lb 
Yasa 400 motor 55 lb 
battery 45 lb(500V)Lone Star Sleeper Cells 
cable electronics 55 lb 

Peter Advice: Use a skinny driver.


----------



## Frank (Dec 6, 2008)

Are you thinking 6S or 12S cells?

I would consider more battery (in parallel). You can make plenty of power with 120S1P but it's probably a good tradeoff to pick up a bit of weight if you can have more consistent sag, especially in cooler temps.


----------



## tropes (Jul 24, 2011)

Frank said:


> Are you thinking 6S or 12S cells?
> 
> I would consider more battery (in parallel). You can make plenty of power with 120S1P but it's probably a good tradeoff to pick up a bit of weight if you can have more consistent sag, especially in cooler temps.


John says 500V 500A could be accomplished with 10 modules of 200X sleeper cells.


----------



## kennybobby (Aug 10, 2012)

The 200C "sleeper cells" are 5 A-hr cells (weight 130 gms) that are rated 100C continuous = 500 Amps, and will do 200C = 1000 A for 1 second, and 625 A for 10 seconds.

The modules are 12S, so 10 modules at 4.15V give 498 Volts and weight of ~40 lbs.

Doubling the pack with parallel cells adds another 40 lbs, and the voltage sag would be greatly reduced if this was determined to be an issue.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> What is the typical weight of a chassis/roll cage structure? front wheel and tire? rear wheel and tire? etc.. just to get some ideas about distribution and weight budget.
> 
> Or maybe just a complete bare bones rolling chassis with adequate safety structure (cage and roll bar).


 
Chris McGee says his complete 180" Jr Comp car weighs 525 lbs. with dry Suzuki engine and Hoosier 24x9-13 tires.
http://mcgeecams.com/jr-comp.html


----------



## kennybobby (Aug 10, 2012)

An idea for an alternative powertrain--a used tesla front drive motor and inverter using Damien's diy tesla controller board found in this thread:

http://www.diyelectriccar.com/forums/showthread.php/diy-tesla-controller-185753.html


The inverter has all the high voltage switching components to handle these high currents and the pack voltage could be reduced to 400 (8 sleeper modules) and take advantage of the 625 Amps for 10 sec rating of the cells.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> An idea for an alternative powertrain--a used tesla front drive motor and inverter using Damien's diy tesla controller board found in this thread:
> 
> http://www.diyelectriccar.com/forums/showthread.php/diy-tesla-controller-185753.html
> .


 
NHRA may have anticipated rebels from the Confederate States coming up with this idea when they included the term "nonautomotive" but I say go ahead and make it happen. It would be a great bracket racer.


----------



## tropes (Jul 24, 2011)

Frank said:


> I would consider more battery (in parallel). You can make plenty of power with 120S1P but it's probably a good tradeoff to pick up a bit of weight if you can have more consistent sag, especially in cooler temps.


Someone previously alluded to cold Canadian temps. The NHRA Northwest National Open Series involved five race tracks from Saskatoon, Saskatchewan to Lewistown, Montana. The track temperatures prior to the four finals we raced ranged from 82°F to 108°. For early morning qualifying runs we used a 120V battery warmer under the battery for about 15 minutes prior to staging. No battery sag due to cool temps.


----------



## Frank (Dec 6, 2008)

Canadian Tire to the rescue? 

What kind of batteries were you using again (can't remember)?


----------



## tropes (Jul 24, 2011)

Frank said:


> Canadian Tire to the rescue?
> 
> What kind of batteries were you using again (can't remember)?


I used these lithium. I still have the 80V with the stand built to accommodate the battery warmer under it.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> An idea for an alternative powertrain--a used tesla front drive motor and inverter using Damien's diy tesla controller board found in this thread:
> http://www.diyelectriccar.com/forums/showthread.php/diy-tesla-controller-185753.html


Jr. Comp rule: "Gear type transmission prohibited". How do you propose to transmit power from motor to rear axle?


----------



## kennybobby (Aug 10, 2012)

i didn't know about that rule...guess that kills that idea. So no Jrs have transmissions or gearboxes in the traditional sense--everything is either chains or belts, no gears?

But the use of a tesla inverter with Damien's board would still be a good idea and hopefully legal to drive your motor. It can handle the power and has cooling capability if needed (for 6.9 second burst it might not require cooling).

It looks like you have everything dialed in except the inverter, and i'm looking at what power and acceleration etc., is needed to make the fastest run without breaking out due to either the ET or speed limits.

i'm indexing all my calculations in post #2 of this thread to have it all in one place.

The inverter to handle this level of power for a short burst is an interesting problem. One could be designed from scratch to meet the requirements, but possibly the tesla drive can be modified to work for less money and time than a custom build. i have an inverter from the mitsubishi imiev, but is limited to 150 Amps at 360V.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> The inverter to handle this level of power for a short burst is an interesting problem. One could be designed from scratch to meet the requirements, but possibly the tesla drive can be modified to work for less money and time than a custom build. i have an inverter from the mitsubishi imiev, but is limited to 150 Amps at 360V.


Interesting problem... I like that. 
I'm leaning toward an inverter designed specifically to meet the requirements. Weight and cooling are two of my concerns.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i'm indexing all my calculations in post #2 of this thread to have it all in one place.


Not sure how this affects your calculations but speed is not always maximum speed. A good driver often lifts if they realize they have won before the end of the eighth mile. This is done to avoid breaking out. Our last junior was capable of running quicker than the legal limit so it was necessary to lift.


----------



## kennybobby (Aug 10, 2012)

Indeed i calculate that to match the minimum ET would violate the maximum speed limit, so a smart driver or current limited inverter would be needed to prevent break out or speed DQ.

There could be a supervisor program in the inverter to ensure that no break out occurs--sort of like a current limiter with timer and smarts to compare the actual trajectory with a stored model. Tesla, Mitsubishi and likely other OEMs have this sort of limiter in there control systems and inverters.

In any case, a current limiter is needed in the inverter such that the battery pack is not over-stressed. The sleeper cells are advertised as capable of 1000A for 1 second, and 625 A for 10 seconds. Can both be done sequentially, or is it just one or the other, and then the cells are depleted. In addition a current limit for motor current is needed such that the windings don't get too hot and melt.

The Azure Dynamics DMOCs are another possible inverter solution, with built in heat sinks and liquid coolant passages. There are several experts on this forum on how those controllers work, there are plenty available and price has come down.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Indeed i calculate that to match the minimum ET would violate the maximum speed limit, so a smart driver or current limited inverter would be needed to prevent break out or speed DQ.


What motor RPM are you using to calculate speed?


----------



## kennybobby (Aug 10, 2012)

That was from a top-down theoretical calculation looking at the kinematics of the acceleration and velocity to run a 6.9 second 1/8 mile. That woud be at a constant acceleration of 0.86g and no friction or aero losses included, just simple math to bound the upper limits. But if you throw the tire circumference and pulley ratio in there it would mean that the motor speed was ~ 6640 RPM. 

In the YASA 400 graph we see that the motor torque falls off above 3000 RPM so it may not be possible to maintain the 0.86g acceleration for the entire run. But from 0 to 3000 RPM with 10:3 pulley ratio and 450A, you would be accelerating at 1.27g assuming the motor could accelerate it's own inertia and that of the small pulley.

i'm trying to figure how to factor in the reduced torque above 3krpm of the motor.

So up to 2.11 seconds you will accelerate at 1.27g and be 91 ft down the track moving at 59 mph. At that time the motor will reach 3000 RPM and start backing off the torque curve and acceleration will fall off.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> That was from a top-down theoretical calculation looking at the kinematics of the acceleration and velocity to run a 6.9 second 1/8 mile. That woud be a constant acceleration of 0.86g and no friction or aero losses included, just simple math to bound the upper limits. But if you throw the tire circumference and pulley ratio in there it would mean that the motor speed was ~ 6640 RPM.


Looking at the physical properties: 5350 rpm -ratio 3.33:1 - 23" tire= 110 mph. To complicate matters the speed in drag racing is calculated in the last 60 feet so it is not the actual speed of the car at the finish line. (60ft /time in seconds between 600 ft. and 660 ft.)Converted to MPH.
Because of the immediate torque, EV times are very different than ICE cars. 60 foot times are much quicker but MPH is much slower. Check the ET's on these time slips. Our 60 ft. times and ET's are quicker but our MPH is much slower.


----------



## kennybobby (Aug 10, 2012)

That's some good data and some good reaction times. The acceleration for the 60' segment comes out to ~1.5 g

With the new motor the 60' times would be 1.7 seconds, with accel ~ 1.27 g. Maybe the new car is heavier?

i need to make a spreadsheet to do the calculations--i'm looking at using small linear segments for the torque drop above 3k rpm, so it requires more integration than i feel like doing by hand.


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> That was from a top-down theoretical calculation looking at the kinematics of the acceleration and velocity to run a 6.9 second 1/8 mile. That woud be at a constant acceleration of 0.86g and no friction or aero losses included, just simple math to bound the upper limits. But if you throw the tire circumference and pulley ratio in there it would mean that the motor speed was ~ 6640 RPM.
> 
> In the YASA 400 graph we see that the motor torque falls off above 3000 RPM so it may not be possible to maintain the 0.86g acceleration for the entire run. But from 0 to 3000 RPM with 10:3 pulley ratio and 450A, you would be accelerating at 1.27g assuming the motor could accelerate it's own inertia and that of the small pulley.
> 
> ...


We were at this point in the calculations long ago... so far back that I won't take the time to search for it. The first-order solution is to accelerate at constant acceleration as long as constant torque is available (you calculated 91 ft and 59 mph; as I recall, I had a bit shorter distance and a similar speed), then constant power for the rest of the run. The torque falls off in proportion to speed, because the motor is power-limited.

Or use the 0-60 calculator which I mentioned earlier. Surely someone following this topic remembers the link?


----------



## brian_ (Feb 7, 2017)

tropes said:


> To complicate matters the speed in drag racing is calculated in the last 60 feet so it is not the actual speed of the car at the finish line


At 62 mph or 100 km/h, which is 28 m/s or 96 ft/s, so that 60 feet only takes 2/3rds of a second... and with acceleration down to a fraction of 1 g (due to the limited power) the car's speed will only increase by at most a couple of metres per second over that stretch.

I suggest just planning to hit the maximum allowed speed at the 1/8 mile mark, so the measured speed over the trap will be a few percent lower and provide a small margin for error to reduce the chance of violating the maximum.



tropes said:


> Because of the immediate torque, EV times are very different than ICE cars. 60 foot times are much quicker but MPH is much slower. Check the ET's on these time slips. Our 60 ft. times and ET's are quicker but our MPH is much slower.


That's the expected result of having more torque available to the wheels (greater initial acceleration), but less peak power (acceleration not maintained at higher speeds).


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> There could be a supervisor program in the inverter to ensure that no break out occurs--sort of like a current limiter with timer and smarts to compare the actual trajectory with a stored model. Tesla, Mitsubishi and likely other OEMs have this sort of limiter in there control systems and inverters.
> 
> In any case, a current limiter is needed in the inverter such that the battery pack is not over-stressed. The sleeper cells are advertised as capable of 1000A for 1 second, and 625 A for 10 seconds. Can both be done sequentially, or is it just one or the other, and then the cells are depleted. In addition a current limit for motor current is needed such that the windings don't get too hot and melt.


Programming a limit to avoid speed disqualification is the straightforward solution to protecting the motor, and to a successful run. A current limit protects the car's components, but it also limits torque to a known value to produce a consistent run.

The final step is to program a power limit for the period between the max-torque and max-speed conditions, again "to protect the battery".

All of this makes sense, but it also nearly fully automates the run, making it extremely consistent; we all realize that consistency is success in bracket racing. My limited understanding of NHRA rules - as applied to engine-driven vehicles - is that this is fundamentally unacceptable, as it reduces the driver's role to reacting to the starting lights and steering in a straight line. I have no idea how they might see this issue, or how they might want to manage it if it is a concern. 

For comparison, even the highest class of road racing (Formula 1) banned driver aids many years ago... so F1 drivers are managing a thousand horsepower of lightweight car without any traction control, stability control, or even ABS. This is done to keep the sport interesting, so it isn't a complete imitation of a 20-car train running perfectly around a track; it's still perilously close to that. 

It wouldn't take much to go from the torque-controlled/power-controlled/speed-limited electric dragster to a completely robotic machine (just add a camera system watching the lights and a GPS straight-line steering function)... and I don't think many fans are wanting that.  It will be interesting to see how this turns out.


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> i need to make a spreadsheet to do the calculations--i'm looking at using small linear segments for the torque drop above 3k rpm, so it requires more integration than i feel like doing by hand.


If you're going to do that, I suggest using time increments (rather than distance), assuming constant power above the constant-torque speed range, and incorporating a speed-dependent aero drag factor. Of course, you might have better ideas, but that's about all I have to contribute at this point.


----------



## brian_ (Feb 7, 2017)

tropes said:


> Jr. Comp rule: "Gear type transmission prohibited".


By "transmission" do they mean a multi-speed transmission, or any transmission of power through gears? I realize that the rulebook contains only that statement, but the reality of rules is that their application depends on a common understanding and precedents for application. This is as true in motorsport as it is in civil or criminal law.

Production "pure" (battery-only) EVs (including Tesla, Nissan Leaf, etc) all have two-stage parallel shaft or one-stage planetary reduction geartrains, but only one fixed ratio. Many people inaccurately refer to this as "no transmission"; I don't know what NHRA thinks "transmission" means.

I haven't heard of anyone using a Tesla motor without the gearbox (although it certainly may have been done), perhaps because it is so obviously sensible to use the gearbox and differential which comes with the motor and has an appropriate reduction ratio and capacity.


----------



## brian_ (Feb 7, 2017)

tropes said:


> My NHRA Rule Book is 2015. The term "nonautomotive" may have been changed.


The 2018 NHRA Junior Dragster rules - including Jr. Comp starting on page 45 - are available online (for anyone who hasn't already found them).

The "nonautomotive" term is still there, as confirmed earlier.

Also, unlike Jr. Dragster, Jr. Comp specifically allows transmissions, including multi-speed transmissions (which you don't need with a suitable motor) with various shift schemes. So any EV transmission is fair game, if it is deemed to be worth the weight. Since no differential is needed (and an open differential is not desired), these transmissions are all built for long-term reliability rather than running for a few seconds at a time, and they are all configured for a relatively wide installation space compared to a Junior Comp Dragster, my guess is that the stock transmission won't be desired.


----------



## brian_ (Feb 7, 2017)

tropes said:


> Presently NHRA recognises only one class of EV's; Electric Junior Dragster. The same flaws exist in the NHRA Junior Dragster class with the same precursor for Electric Juniors.
> My experience has led me to believe that the best approach is to "keep it simple". Therefore, I believe the best chance of being accepted is to add "electric motor" to their list of "badly flawed" engine requirements. Omitting their term "nonautomtive" may be contentious but that could be negotiated.


"Keep it simple" is good, and the simplest rule is no rule. If Jr. dragster allows electric propulsion then no rule is required at all, and electric is already legal in Jr. Comp unless stated otherwise in the Jr. Comp rules. Since Jr. Comp apparently does not allow electric propulsion then the engine statement is assumed to be an inclusive list (_if it isn't listed it isn't allowed_) so adding "or electric motor(s)" to the end of the first sentence of the engine rule is the simplest change to the Jr. Comp rules. This would fail to provide any rational limit on power. It would not carry any of the nonsensical restrictions into electric entries, but there's no known reason to believe that this would be a problem. So, what is the intent of the existing rules, which needs to be preserved in the extension to electric power?

I also note the disturbing statement:


> Must be NHRA accepted.


This appears to apply globally - to all engines (and thus motors) from any source - and so is a disturbingly arbitrary restriction. 
Is an NHRA official just confirming that a particular choice conforms to the rest of the rule? Then this statement is not needed, as that is what tech does anyway.
Is it saying that engines (now motors) must be confirmed to conform in advance, rather than leaving it to the event day? That makes sense, but it would be wise to ask for confirmation long in advance of any event... and presumably in advance of buying anything or even finalizing design.

It also makes sense to consider your own interests. In this case... wouldn't the planned YASA motor be banned by any "non-automotive" requirement, since it is sold specifically for automotive applications? I would want to avoid that.


----------



## kennybobby (Aug 10, 2012)

Here is a first cut look at a time history using the YASA 400 motor torque curve from post#1. The red line is speed, blue is distance. The solid line has no aero or friction loads, the dashed lines shows some loading that would be needed to hit the target without breaking out. The target box is shown in green, with ET of 6.9 sec and speed of 161 ft/sec.


----------



## tropes (Jul 24, 2011)

tropes said:


> Jr. Comp rule: "Gear type transmission prohibited". How do you propose to transmit power from motor to rear axle?


Correction: Geared transmission not allowed for Junior Dragster but* allowed* for Jr. Comp.
However, my experience tells me that any transmission not attached to an allowed engine would not be allowed.
Interpretation of NHRA rules has always been clouded by the fact that the rules are "the result of arguments based on the experience and commercial interests of some participants and their sponsors." None of the major sponsors have an interest in Electric Vehicles.


----------



## tropes (Jul 24, 2011)

brian_ said:


> It also makes sense to consider your own interests. In this case... wouldn't the planned YASA motor be banned by any "non-automotive" requirement, since it is sold specifically for automotive applications? I would want to avoid that.


The most popular Jr Comp engine is a Suzuki. Suzuki has been an automobile manufacturer for years but also builds motor cycles.
According to Yasa Motors The YASA-400 was developed for higher speed and power applications. These applications include: Hybridisation, Traction and Propulsion, Power Generation, Electro-Hydraulic Hybrids, Hydraulics Replacement.
Unlike the Tesla, Toyota Prius, Chevrolet Bolt, Yasa does not build an electric vehicle.


----------



## brian_ (Feb 7, 2017)

tropes said:


> Correction: Geared transmission not allowed for Junior Dragster but *allowed* for Jr. Comp.
> However, my experience tells me that any transmission not attached to an allowed engine would not be allowed.


At least that should be a relatively easy argument - there's nothing at all in the published rule about where the transmission is located or to what it is attached.



tropes said:


> Interpretation of NHRA rules has always been clouded by the fact that the rules are "the result of arguments based on the experience and commercial interests of some participants and their sponsors."






tropes said:


> None of the major sponsors have an interest in Electric Vehicles.


Sure, but sponsors do have an interest in ensuring that their gas-engine cars don't lose to electric cars, right? Start winning, and I think they'll be interested in you and the rules applicable to your car.


----------



## tropes (Jul 24, 2011)

brian_ said:


> At least that should be a relatively easy argument - there's nothing at all in the published rule about where the transmission is located or to what it is attached.


I think it best to avoid such argument.
In order for this hypothetical Jr. Comp vehicle to become reality one obstacle must be overcome: Inclusion of Electric Powered Jr. Comp.
I have long been convinced that electric powered vehicles have an advantage over ICE's in some NHRA classes but I have witnessed a fear that the electric advantage will lead to an electronic component that will replace the direct function of the driver.
In order to break into the NHRA establishment this fear must be overcome.
Members of this forum have reinforced my belief that an Electric would be competitive in the NHRA Jr. Comp class. We must urge the NEDRA executives who have established communication with NHRA to negotiate an agreement that would allow this inclusion.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> With the new motor the 60' times would be 1.7 seconds, with accel ~ 1.27 g. Maybe the new car is heavier?


The Junior weighed 375 lbs. with driver. The Jr. Comp car would weigh 755 lbs.. Comparing the Junior Dragster and the Jr. Comp 60 ft. times, 1.57 and 1.70 there is a large gap between these times. Is this solely due to weight? 
The specs on the junior motor are available here: http://www.lightswitchracing.com/K91-4003.pdf


----------



## kennybobby (Aug 10, 2012)

It looks like higher low-end torque for the K91 vs the YASA, in addition to the difference in weight, (plus smaller tires and higher pulley ratio?).

But the greater power of the yasa turns the tables at the 330', 4 seconds vs 5.1 for the Jr.

i suspect that the YASA chart is just a parametric graph not based upon real dyno test data.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is a first cut look at a time history using the YASA 400 motor torque curve from post#1. The red line is speed, blue is distance. The solid line has no aero or friction loads, the dashed lines shows some loading that would be needed to hit the target without breaking out. The target box is shown in green, with ET of 6.9 sec and speed of 161 ft/sec.


Can you plug in some variables: Ratio 3.67:1 (30,110) and Weight 735 lbs. and a combination of these.


----------



## kennybobby (Aug 10, 2012)

Same format as previously with lower weight (735 lbs) and 110:30 pulley ratio, and without aero or friction loads.


----------



## tropes (Jul 24, 2011)

I contacted a retired friend at Visions Race Cars http://visionsracecars.com/ who sent this reply:"I am retired now but still interested in your project I have a spare chassis 
sitting keep me up dated"
I asked him to give a weight and length of the chassis and will keep him updated.
Light Switch Racing also has sponsors who are willing to contribute if we are able to find a young racer who is committed to the project.


----------



## tropes (Jul 24, 2011)

This is a photo of a Jr. rolling chassis built by Visions. The Junior Comp chassis is longer and weighs more.


----------



## tropes (Jul 24, 2011)

I contacted Bill Newman at Next Step Racing to get a more accurate weight estimate.
This is his reply:

_"Hi Peter, I do Currently own a Hayabusa Powered Jr Comp Dragster as well as having owned and operated several others. Additionally I have been involved with building several new cars, reworking and refurbishing several used cars as well as selling numerous used cars out right._
_. _
_Your question as asked, asked me to presume what the weight would be of a chassis/roller of your design with very little information of what that chassis/roller would entail._
_I would guess, and please correct me if I am wrong, you are looking at weight vs output numbers to calculate performance?_
_For a initial calculation, a base weight of 400lbs plus Batteries, Controller, Cabeling and Driver weight should put you in the ballpark of what I think you are looking for." _

As a result, I must reduce the probable weight to 700 lbs (assuming a 140 lb driver).


----------



## kennybobby (Aug 10, 2012)

Well that's good news, losing weight on a dragster is bound to improve ET. i'll run the numbers again with 700 lbs.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Well that's good news, losing weight on a dragster is bound to improve ET. i'll run the numbers again with 700 lbs.


3.33:1 ratio. Mainly concerned with ET. We should look at dropping voltage to 400V.


----------



## kennybobby (Aug 10, 2012)

Here's the chart for 700 lbs and 3.33 ratio. The distance curve in feet on the left axis (blue), speed curve in ft/sec on the right (red). 

The green box is where you must finish to not be disqualified--both curves must end up in the green box, with distance below the 660' line when it crosses in 6.9 seconds.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here's the chart for 700 lbs and 3.33 ratio.


There are a few mechanical options (add weight, gear ratio, lift accelerator). Since the power to weight ratio is resulting in a quicker ET we could reduce the voltage. Dropping voltage worked for us with the Junior so could you give us a chart for 700 lbs. 3.33 ratio showing an approximate ET with less voltage.


----------



## kennybobby (Aug 10, 2012)

Here is a 400V, 400A, 700lbs, 3.33 ratio chart showing ET at 1/8 mile.

Realizing this is just spreadsheet calculatus without real loads, aero, friction etc, and assuming the motor performs according to the datasheet chart, which was also likely just parameter extrapolation (i doubt that was real test data).

i put your jr dragster times as the green dashed line with stars for comparison.

Do you have the motor specs for the jr dragster? Also what voltage, current, weight, gear ratio, tire size, etc--maybe we can run the theoretical performance for that and compare with the actual timeslips to get an idea of the expected aero and friction loads.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Do you have the motor specs for the jr dragster? Also what voltage, current, weight, gear ratio, tire size, etc--maybe we can run the theoretical performance for that and compare with the actual timeslips to get an idea of the expected aero and friction loads.


Motor AdvancedDC K91-4003
http://www.evmotors.com.au/products/download/K91-4003.pdf

100V 800Amp
375 lbs.
3.9:1 ratio Drive to Driven 
18" tire D
Average ET- 8.91 sec. 
Average speed- 62 mph
Average 60' time- 1.56 sec
Average 330' time- 5.169 sec


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is a 400V, 400A, 700lbs, 3.33 ratio chart showing ET at 1/8 mile.
> 
> Realizing this is just spreadsheet calculatus without real loads, aero, friction etc, and assuming the motor performs according to the datasheet chart, which was also likely just parameter extrapolation (i doubt that was real test data).


Can we assume an aerodynamic drag coefficient of 0.09 and a rolling friction coefficient of 0.02?


----------



## kennybobby (Aug 10, 2012)

We can use those numbers--need the frontal surface area, or height x width.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> We can use those numbers--need the frontal surface area, or height x width.


Difficult to calculate surface area but 2' x 2' is close.


----------



## kennybobby (Aug 10, 2012)

how tall is the top of the cockpit--we can use that for height.

gotta run to a hockey game tonight, will get back to it tomorrow.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> gotta run to a hockey game tonight, will get back to it tomorrow.


Nashville Cats?


----------



## kennybobby (Aug 10, 2012)

i wish, but we have a local SPHL team, the Havoc vs Peoria Rivermen.

Just looking at the picture, if the tires are 18", then top of rollbar is up around 36"?


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Just looking at the picture, if the tires are 18", then top of rollbar is up around 36"?


Those tires are 22". Roll cage does not extend to the ground so let's use 6 square feet as frontal surface area.


----------



## kennybobby (Aug 10, 2012)

Here is an attempt to calculate ET for the 375lb Jr using the -4003 motor datasheet for 75V and extrapolate out to 800 Amps, 18" tires, 3.9:1, no aero or friction. It shows a slightly longer ET than your average (9.6 vs 8.9), and a slower speed at the line. i added green stars for your timeslip data at 60, 330, and 1/8th mile.

i think part of the difference is due to the chart voltage of 75 and your actual system using 100V. i used a some linear approximations for parts of the k91-4003 motor torque-speed curve and this came fairly close to what you were actually running--possibly we could sharpen our pencils and get it closer, but this is a farily good first cut all things considered.


----------



## Frank (Dec 6, 2008)

tropes said:


> Can we assume an aerodynamic drag coefficient of 0.09 and a rolling friction coefficient of 0.02?


I think the .09 is a bit optimistic. Most streamliners don't achieve that. I would use .4 or .5.

BTW, I've kind of lost track of what's going on here: are you tweaking the model based on data from the old junior?

Happy New Year!


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i think part of the difference is due to the chart voltage of 75 and your actual system using 100V. i used a some linear approximations for parts of the k91-4003 motor torque-speed curve and this came fairly close to what you were actually running--possibly we could sharpen our pencils and get it closer, but this is a farily good first cut all things considered.


The car weighed 275 lbs when we went from the 72V polymer to the 96V Li ion and our driver weighed 95 lbs with her helmet on so I may be slightly heavy with my estimate. Our 60 ft times were always better than the competition because of instant torque. We ran between 4.2 and 4.7 pounds of air pressure depending on track conditions which allowed us to "shock the tires". That meant that they wrinkled before the car moved which allowed the driver to leave on the last yellow and the RPM was not at 0 when she left the starting line. The Curtis pot box was scrapped and the controller was changed to accept the inductive throttle which improved our 60 ft times and ET. It was like turning on a "Light Switch".
If it is of any value, I once calculated that the car ran the last 60 ft at 90 ft per second and motor RPM was 4200.


----------



## tropes (Jul 24, 2011)

Frank said:


> I think the .09 is a bit optimistic. Most streamliners don't achieve that. I would use .4 or .5.
> 
> BTW, I've kind of lost track of what's going on here: are you tweaking the model based on data from the old junior?
> 
> Happy New Year!


Yes. kennybobby is using old data. How do you arrive at .4 or .5

Happy New Year!


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is a 400V, 400A, 700lbs, 3.33 ratio chart showing ET at 1/8 mile.


Going with 400V battery rather than 500V would reduce the total weight by about 8 lbs.


----------



## kennybobby (Aug 10, 2012)

@Peter,
i revised the previous chart to add your timeslip data.

i don't think 7 to 10 lbs would make that big a difference--i think the bigger effect is running 100 V versus the datasheet at only 75 V. As you know the speed is related to the voltage, and the torque is proportional to current. But a higher system voltage allows both more speed and torque.

so for Jr Comp, if you could get the high currents with the minimum voltage required to hit the 6.9 sec ET, that would be ideal from a pack size and weight and system standpoint.

@Frank, yes we are looking at the previous Jr dragster data to access the model validity by comparing with known test data. i think the calculatus is okay at this level based upon fairly good agreement with the timeslips, but i haven't folded in the aero and friction estimates yet.

Basically i was hoping to provide some reasonable estimates to show whether or not the Jr. Comp is feasible with the weight, motor, pack voltage, tire size, gear ratio and other items.

If we can show this is close to what we could expect to see, then it would be possible to spec out the pack and motor controller, i.e. 400 V vs 500 V, current rating of transistors, etc...

Happy New Year, i'm excited to see what sort of great things will happen in 2018!


----------



## tropes (Jul 24, 2011)

kennybobby said:


> @Peter,
> i revised the previous chart to add your timeslip data.
> so for Jr Comp, if you could get the high currents with the minimum voltage required to hit the 6.9 sec ET, that would be ideal from a pack size and weight and system standpoint.
> 
> ...


ET can also be shortened by staging shallow. This allows for a bit of a running start.


----------



## Frank (Dec 6, 2008)

tropes said:


> Yes. kennybobby is using old data. How do you arrive at .4 or .5


Just a guess really... anything with open wheels is going to be high. Have a look here for production vehicles. 

http://ecomodder.com/wiki/index.php/Vehicle_Coefficient_of_Drag_List

It'd be fun to try a coastdown test. I'm actually converting a small formula car to e-drive and have thought about this.


----------



## tropes (Jul 24, 2011)

Frank said:


> Just a guess really... anything with open wheels is going to be high. Have a look here for production vehicles.
> 
> http://ecomodder.com/wiki/index.php/Vehicle_Coefficient_of_Drag_List


I don't know how to apply the coefficient but I did find this:
https://commons.wikimedia.org/wiki/File:Drag.png

The world is hoping for greater things in 2018.


----------



## kennybobby (Aug 10, 2012)

oh yeah a coastdown test is good data, have done that in the past with formula 24 cars for the high school kids. Probably need some sort of data acq system for a dragster to record data automagically.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is a 400V, 400A, 700lbs, 3.33 ratio chart showing ET at 1/8 mile.
> Realizing this is just spreadsheet calculatus without real loads, aero, friction etc, and assuming the motor performs according to the datasheet chart, which was also likely just parameter extrapolation (i doubt that was real test data).
> 
> maybe we can run the theoretical performance for that and compare with the actual timeslips to get an idea of the expected aero and friction loads.


Okay, so if we have, for example, a theoretical speed of 80 mph tell me how to apply a drag coefficient of .3 to get an actual speed.
(without using the perfect passive participle of calculo.)


----------



## MPaulHolmes (Feb 23, 2008)

Peter was saying he might be interested in a chevy volt inverter for this, and that I should chime in. The volt inverter is 2 separate inverters. I don't know if you are running 2 motors, but I think it could do 2 at around 110kW each. I did a control board for it that could be configured to run the 2 IGBT 6 packs in parallel, or 2 motors separately, but I haven't tested how well they would current share if you tried parallel mode with a single motor.

The Chevy volt inverter was not happy with voltages above 400v though. the driver board broke at around 410v, but it was good all the way down to around 36vDC. That was with nothing but the driver board hooked up to a high voltage supply. It's possible that there was a part on it that intentionally fails to save the power section, but I'm not sure.


----------



## tropes (Jul 24, 2011)

MPaulHolmes said:


> Peter was saying he might be interested in a chevy volt inverter for this, and that I should chime in. The volt inverter is 2 separate inverters. I don't know if you are running 2 motors, but I think it could do 2 at around 110kW each. I did a control board for it that could be configured to run the 2 IGBT 6 packs in parallel, or 2 motors separately, but I haven't tested how well they would current share if you tried parallel mode with a single motor.
> 
> The Chevy volt inverter was not happy with voltages above 400v though. the driver board broke at around 410v, but it was good all the way down to around 36vDC.


Thank you Paul for joining us. This is not my field of expertise but there are those in this group that will be able to ask the right questions. If they feel you have an inverter that will work for this project I am willing to purchase it with a control board.


----------



## tropes (Jul 24, 2011)

MPaulHolmes said:


> The Chevy volt inverter was not happy with voltages above 400v though. the driver board broke at around 410v, but it was good all the way down to around 36vDC. That was with nothing but the driver board hooked up to a high voltage supply. It's possible that there was a part on it that intentionally fails to save the power section, but I'm not sure.


Paul I know you have had some experience with the Yasa 400 motor. We are looking at using a single motor with 400V. Is the problem with the Chevy Volt inverter or the driver board? Is time a factor since max power is used for only 7 seconds. What about cooling for motor and inverter?


----------



## MPaulHolmes (Feb 23, 2008)

Yes I've got the yasa running before. sombody let me borrow it. The stock chevy volt driver board has a high voltage DC/DC converter on board to generate the 17v for driving the IGBTs. It just really really doesn't like over 400v. All I know is, like a light switch, the volt driver board broke above 410v. It does have nice liquid cooling, and so does the yasa. If you want to do 400v, either the stock driver board may need to be modified, or replaced, or you would need a different controller. It's possible that it was forced to fail on purpose, so maybe the driver board could be tricked into thinking it is getting a lower voltage, so it wouldn't break. Thats' a guess though. This is why I always make isolated power for the driver boards from the input control voltage, so the high voltage section can be anything you want from 0 up to like 800v. It's more expensive, so for something like the volt, where they know their exact voltage range, it's not worth the extra cost.


----------



## tropes (Jul 24, 2011)

MPaulHolmes said:


> Yes I've got the yasa running before. sombody let me borrow it. The stock chevy volt driver board has a high voltage DC/DC converter on board to generate the 17v for driving the IGBTs. It just really really doesn't like over 400v. All I know is, like a light switch, the volt driver board broke above 410v. It does have nice liquid cooling, and so does the yasa. If you want to do 400v, either the stock driver board may need to be modified, or replaced, or you would need a different controller. It's possible that it was forced to fail on purpose, so maybe the driver board could be tricked into thinking it is getting a lower voltage, so it wouldn't break. Thats' a guess though. This is why I always make isolated power for the driver boards from the input control voltage, so the high voltage section can be anything you want from 0 up to like 800v. It's more expensive, so for something like the volt, where they know their exact voltage range, it's not worth the extra cost.


On the drawing I sent you I have an auxiliary battery. 








Rather than a DC/DC converter could you use a low voltage auxiliary battery to drive the switches?


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is a 400V, 400A, 700lbs, 3.33 ratio chart showing ET at 1/8 mile.











Allowing for drag and friction, the ET (6.3) is in the acceptable range but the Speed is off the chart. Any explanation?


----------



## major (Apr 4, 2008)

tropes said:


> ...Rather than a DC/DC converter could you use a low voltage auxiliary battery to drive the switches?


Sure. I'd use a Lithium tool battery and carry a spare. Just give yourself an easy way to check voltage on it and do that often. Some types of tool batteries just shut down when out of charge and you don't want that during a run. I've used a Craftsman 12 V, 1 Ah Nextec battery on a race kart. Same as for some of the pit tools.

major


----------



## kennybobby (Aug 10, 2012)

tropes said:


> Allowing for drag and friction, the ET (6.3) is in the acceptable range but the Speed is off the chart. Any explanation?


The original chart is in post #107, this is just zoomed in to show ET at distance and compare to the Jr. car timeslips. This is a quicker car than the Jr., and the speed curve is out of the box for all the versions so far, 755 lb, 735 lb, 700 lb. Aero and friction is on todo list...


----------



## tropes (Jul 24, 2011)

major said:


> Sure. I'd use a Lithium tool battery and carry a spare. Just give yourself an easy way to check voltage on it and do that often. Some types of tool batteries just shut down when out of charge and you don't want that during a run. I've used a Craftsman 12 V, 1 Ah Nextec battery on a race kart. Same as for some of the pit tools.
> 
> major


Good. What minimum voltage is needed to drive the IGBT's?


----------



## major (Apr 4, 2008)

tropes said:


> Good. What minimum voltage is needed to drive the IGBT's?


The IGBT drivers are isolated power supplies in the controller which take power from the main DC bus. By 'switch' I thought you were referring to the external contactor(s), and auxiliary items like idiot lights.

major


----------



## tropes (Jul 24, 2011)

kennybobby said:


> The original chart is in post #107, this is just zoomed in to show ET at distance and compare to the Jr. car timeslips. This is a quicker car than the Jr., and the speed curve is out of the box for all the versions so far, 755 lb, 735 lb, 700 lb. Aero and friction is on todo list...


Just checked the NEDRA 1/8th mile records and John Metric ran a 156 MPH in 4.8 sec. with 400 volts in a lead sled that weighed a ton and a half. His numbers may be of help.
http://www.nedra.com/record_holders.html


----------



## tropes (Jul 24, 2011)

major said:


> The IGBT drivers are isolated power supplies in the controller which take power from the main DC bus. By 'switch' I thought you were referring to the external contactor(s), and auxiliary items like idiot lights.
> 
> major


I was thinking about Paul's comment on tricking the driver board. So is it possible to use auxiliary battery to do both idiot lights and drive IGBT's?


----------



## major (Apr 4, 2008)

tropes said:


> I was thinking about Paul's comment on tricking the driver board. So is it possible to use auxiliary battery to do both idiot lights and drive IGBT's?


That wouldn't work so well. Typically you have 6 IGBTs and each has its own isolated driver. The driver connects to the IGBT gate and emitter. The gate is isolated (hence IG) but the emitter is "hot". The emitters on the 3 IGBTs on the lower rail are common to the negative DC bus. So you might get by with only 4 batteries to drive the 6 gates but that would make for some unique circuits. Also each gate driver needs to swing both positive (turn on) and negative (turn off). Just too messy to use separate battery supplies, IMO.

major


----------



## tropes (Jul 24, 2011)

MPaulHolmes said:


> It's possible that it was forced to fail on purpose, so maybe the driver board could be tricked into thinking it is getting a lower voltage, so it wouldn't break. Thats' a guess though. This is why I always make isolated power for the driver boards from the input control voltage, so the high voltage section can be anything you want from 0 up to like 800v.


So how do you trick the driver board?


----------



## Batterypoweredtoad (Feb 5, 2008)

MPaulHolmes said:


> Peter was saying he might be interested in a chevy volt inverter for this, and that I should chime in. The volt inverter is 2 separate inverters. I don't know if you are running 2 motors, but I think it could do 2 at around 110kW each. I did a control board for it that could be configured to run the 2 IGBT 6 packs in parallel, or 2 motors separately, but I haven't tested how well they would current share if you tried parallel mode with a single motor.
> 
> The Chevy volt inverter was not happy with voltages above 400v though. the driver board broke at around 410v, but it was good all the way down to around 36vDC. That was with nothing but the driver board hooked up to a high voltage supply. It's possible that there was a part on it that intentionally fails to save the power section, but I'm not sure.


Would you be interested/willing to build that board/kit to sell? Volt inverters are incredibly cheap so it would be a nice way to get into a decent AC setup for a reasonable price.


----------



## tropes (Jul 24, 2011)

Batterypoweredtoad said:


> Would you be interested/willing to build that board/kit to sell? Volt inverters are incredibly cheap so it would be a nice way to get into a decent AC setup for a reasonable price.


Good idea, but if you wish to do business contact Paul directly rather than on this forum.


----------



## Batterypoweredtoad (Feb 5, 2008)

tropes said:


> Good idea, but if you wish to do business contact Paul directly rather than on this forum.


I considered that but decided to post here first. The thread mentioned using a volt controller and Paul chimed in with ways it may be done including the fact that he has done it. I intentionally put my question here because the answer may benefit the thread starter and other forum members. There was no harm intended.


----------



## tropes (Jul 24, 2011)

One other motor option to consider is the AF-140 made by Avid.








https://avidtp.com/product/evo-motors/


----------



## brian_ (Feb 7, 2017)

tropes said:


> The most popular Jr Comp engine is a Suzuki. Suzuki has been an automobile manufacturer for years but also builds motor cycles.


Okay, but the specific Suzuki engines are for motorcycles, and the rule explicitly allows motorcycle engines... implying that motorcycles are "non-automotive". What else the same manufacturer (such as Suzuki, Honda, or BMW) produces seem irrelevant to me.



tropes said:


> According to Yasa Motors The YASA-400 was developed for higher speed and power applications. These applications include: Hybridisation, Traction and Propulsion, Power Generation, Electro-Hydraulic Hybrids, Hydraulics Replacement.
> Unlike the Tesla, Toyota Prius, Chevrolet Bolt, Yasa does not build an electric vehicle.


Right - that's hybridization *of automobiles*. The rule doesn't mention the product range of manufacturers, only whether or not the engine (and motor in this proposal) is automotive.

Lots of components are automotive, even though they are made by suppliers, not the automobile OEMs themselves. If anyone running a gasoline engine doesn't like electric competition, including the non-automotive qualifier explicitly is inviting them to protest any entry powered by any motor which is used in anything they consider "automotive".

This "non-automotive" thing is a mess, and I would certainly avoid getting tangled up in it unnecessarily by including it explicitly.


----------



## brian_ (Feb 7, 2017)

Frank said:


> I think the .09 is a bit optimistic. Most streamliners don't achieve that. I would use .4 or .5.


I agree!
The frontal area includes rear tire protrusion, and the shape includes both those and the front tires (which are narrow but horrendously high-drag). The open cockpit is also terrible for drag.



tropes said:


> How do you arrive at .4 or .5


That range seems reasonable to me by comparison with other vehicles.

In the illustration of typical shapes linked later, any car is far closer to the half-ball than the streamlined bump. Stuff sticking out - and a dragster positively bristles with stuff sticking out, including the front suspension and wheels, driver, roll cage, and rear wheels - is death to low drag... but those basic shapes don't show that.


----------



## tropes (Jul 24, 2011)

brian_ said:


> Okay, but the specific Suzuki engines are for motorcycles, and the rule explicitly allows motorcycle engines... implying that motorcycles are "non-automotive". What else the same manufacturer (such as Suzuki, Honda, or BMW) produces seem irrelevant to me.
> 
> This "non-automotive" thing is a mess, and I would certainly avoid getting tangled up in it unnecessarily by including it explicitly.


Agreed. I am hopeful that NEDRA will ask for my input when the time comes to include electric motors in their (NHRA, IHRA) rules.
BTW, Super 7 cars Inc. is a manufacturer in Canada and the UK that builds automobiles using the Suzuki Hayabusa engine. http://www.super7cars.com/


----------



## tropes (Jul 24, 2011)

brian_ said:


> I agree!
> That range seems reasonable to me by comparison with other vehicles.
> In the illustration of typical shapes linked later, any car is far closer to the half-ball than the streamlined bump. Stuff sticking out - and a dragster positively bristles with stuff sticking out, including the front suspension and wheels, driver, roll cage, and rear wheels - is death to low drag... but those basic shapes don't show that.


If we use .45 as the drag coefficient and .02 as the coefficient of friction, how do we apply that to the speed-126 mph and ET-5.8 sec in kennybobby's chart (post #107)?


----------



## brian_ (Feb 7, 2017)

tropes said:


> If we use .45 as the drag coefficient and 1 as the coefficient of friction, how do we apply that to the speed-126 mph and ET-5.8 sec in kennybobby's chart (post #107)?


I assume that kennybobby is using the drag coefficients in his calculations to determine the net force available to accelerate in each increment of the run. The only way to see the effect of a change in either coefficient would be to re-run the calculation.


----------



## kennybobby (Aug 10, 2012)

i'm working on it--just not full-time...

here is the load (in HP) vs speed (mph) chart for 700 lbs, 0.4 Cd and 0.02 Crr. i will re-run for 0.45 Cd and then fold it into the ET chart.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i'm working on it--just not full-time...
> 
> here is the load (in HP) vs speed (mph) chart for 700 lbs, 0.4 Cd and 0.02 Crr. i will re-run for 0.45 Cd and then fold it into the ET chart.


Thanks kennybobby, I appreciate your part time job.


----------



## kennybobby (Aug 10, 2012)

Here's a chart to estimate the effect of the loads on a 700 lbs Jr Comp dragster with 3.33 gear ratio, 0.45 Aero Cd, 0.02 Crr Friction, using the Yasa 400 motor at 400 Volts and 400 Amps. 

The red and yellow traces are speed in ft/sec, the gray and blue are distance in ft.


p.s. Those Avid motors look very similar to the YASA motors, and an interesting video on their site.

[EDIT]
Disregard this chart, the discontinuity in the speed line was caused by an error in the spreadsheet calculation and the ET is wrong. The corrected chart is found on the next page of this thread.


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> i'm working on it--just not full-time...
> 
> here is the load (in HP) vs speed (mph) chart for 700 lbs, 0.4 Cd and 0.02 Crr...


Good stuff!


----------



## brian_ (Feb 7, 2017)

tropes said:


> BTW, Super 7 cars Inc. is a manufacturer in Canada and the UK that builds automobiles using the Suzuki Hayabusa engine. http://www.super7cars.com/


I've never driven a Super 7 (original Lotus or current Caterham) or any of the many cars which imitate it, but they're almost universally hailed as among the most fun things on the road, with any of the many engines offered.  Duncan's _Dubious Device_ is an example of the "Locost" style of home-built car, which is inspired by the Seven and copies the general layout and tube-frame construction, although there are no mechanical details of the _Device_ which are similar to an actual Lotus 7.

The engine of the Suzuki Hayabusa (often known as the "Busa") is very popular in small kit and racing cars. There are other bike engines used this way, and some car-style trikes that have a Harley engine hanging off the front. Does that make these "automotive engines"? I don't think so, any more than the use of engines sourced from motorcycles in Jr. Comp dragsters makes them drag racing car engines, or the use of Suzuki, Honda, GM, Mercedes, VW, Subaru, and other car engines in aircraft make them aircraft engines.

When Honda started making cars, they built an engine which essentially copied their motorcycle units. Even in the 1980's when I saw Honda Civic engines in my friend's competition cars, they seemed closer to motorcycle than typical car design. The engine really doesn't know what it is driving.

In case it isn't apparent, I would _really_ avoid this "automotive/non-automotive" mess in rules.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here's a chart to estimate the effect of the loads on a 700 lbs Jr Comp dragster with 3.33 gear ratio, 0.45 Aero Cd, 0.02 Crr Friction, using the Yasa 400 motor at 400 Volts and 400 Amps.
> 
> This is showing that you would not be disqualified for either time or speed, the 1/8th mile ET went from 6.2 to 9.2 seconds, and the speed is under 110 mph (160 ft/sec) The red and yellow traces are speed in ft/sec, the gray and blue are distance in ft.


It's a long way from 9.2 to 6.9. Unless these coefficients are high I don't see a way to use this motor. The Junior dragster shape and frontal area are very similar to the Jr Comp car. How do these Aero and Friction numbers play out when applied to the Junior Dragster?


----------



## kennybobby (Aug 10, 2012)

i suspect the coeff are too high. Surely someone has measured Cd for a typical dragster body. A timed coast-down test could provide some great data to determine real loads.

The jr car calculation without loads was only slightly quicker than the actual timeslips (the green stars on the jr chart)--so the loads don't appear to be very high for that car.

But a 375lb car with an 800 Amp motor makes more torque and has higher acceleration than a 700 lb car with only 400 Amps.


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> i suspect the coeff are too high. Surely someone has measured Cd for a typical dragster body. A timed coast-down test could provide some great data to determine real loads.


Real data would be nice, and can be from a car with any engine or motor, as long as the body and tires are comparable (a Top Fuel dragster will have a much larger frontal area and higher CD due to the rear tires). While my understanding is that NHRA bans electronic driver aids, I don't know what restrictions they have - if any - on data logging systems. If people are not running data loggers, they won't likely have coast-down data, and even if they are logging run data, I don't know how far (if at all) they coast before braking.

I suppose anyone running a 1/8th mile race on a 1/4 mile track with only one return road at the end likely does coast for a while after clearing the 1/8th mile mark. For instance, at Castrol Raceway there appear to be two turn-offs to the return road, but even the closer one is at almost 1/2 mile past the 1/8th mile trap.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Constants and Constraints:
> race distance: 1/8 mile = 660 ft
> max speed: 110 mph = 161.3 ft/sec
> minimum ET: 6.9 sec
> ...


Since this post #2 using 500V 500A, the weight has dropped to 700 lbs. Could this difference make it possible to use the Yasa motor?


----------



## kennybobby (Aug 10, 2012)

You have to realize that this is very crude and low fidelity data that we are dealing with, so don't make any purchase decisions based upon these few charts.

0.45 Cd seems too high for a streamlined body like a dragster. i have asked for a sanity check on one of the aerodynamic forums, so let's see what some of those experts have to say.

[EDIT]
i found an error in the calculation--the discontinuity in the lines of the previous graph was bothering me so i went back thru it to find out what was causing the noise.

So this revised graph should make you feel better about the Yasa motor using 0.45 Cd and 0.02 Crr, 700 lbs, 3.3 GR, 400 Volts and 400 Amps.

The difference between loaded and unloaded is comparable to the Jr car unloaded calculation and the timeslips, so i feel like this is reasonable.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i found an error in the calculation--the discontinuity in the lines of the previous graph was bothering me so i went back thru it to find out what was causing the noise.
> 
> So this revised graph should make you feel better about the Yasa motor using 0.45 Cd and 0.02 Crr, 700 lbs, 3.3 GR, 400 Volts and 400 Amps.
> 
> The difference between loaded and unloaded is comparable to the Jr car unloaded calculation and the timeslips, so i feel like this is reasonable.


The 60' time seems high compared to the 1/8th mile ET but if these are the numbers using .45 CD then it is encouraging. Have you had any feedback from the aerodynamic gurus?
Can you adjust the weight to match a 6.9 ET?


----------



## kennybobby (Aug 10, 2012)

900 lbs shifts the ET out to the 6.9 region.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> 900 lbs shifts the ET out to the 6.9 region.


Adding 200 lbs seems a bit drastic. Using a 3.5 gear ratio (28-98) would get us closer to a 6.9 ET.


----------



## brian_ (Feb 7, 2017)

tropes said:


> Adding 200 lbs seems a bit drastic. Using a 3.5 gear ratio (28-98) would get us closer to a 6.9 ET.


So, is the conclusion that a suitable combination of components is available, and can be reasonably expected to produce performance at the class limits, so it's time to proceed with detailed design... and tune performance with gearing and controller limits later?


----------



## tropes (Jul 24, 2011)

brian_ said:


> So, is the conclusion that a suitable combination of components is available, and can be reasonably expected to produce performance at the class limits, so it's time to proceed with detailed design... and tune performance with gearing and controller limits later?


kennybobby says, "don't make any purchase decisions based upon these few charts." so I'm waiting for the word.


----------



## kennybobby (Aug 10, 2012)

So i tried to make a comparison between 3.5 and 3.3 gear ratio, but the difference is very slight, about 0.1 seconds faster for the same weight. And this all assumes quite a bit.

Using a small thin line on a graph presupposes that we have good knowledge of the motor torque versus speed curve, good knowledge of the aero coeff and rolling resistance, etc. The truth of the matter is that we only have very coarse estimates of these things and our pencils are not as sharp as we have drawn. A fat pencil or marker or crayola would be a more honest representation of the results to show the uncertainty of the truth.

In addition there is a bunch of manual data entry required to make any changes in the calculations and that is always another source of errors.

For example, here is a comparison of two calculation methods that should give the same results, but as you can see that they don't, especially down at the 0-60' region.


----------



## kennybobby (Aug 10, 2012)

So here is 900lbs with 3.5GR in blue, and 3.3 in red, drawn thin, but using the crude calculation method (because if has fewer data points to enter manually).


----------



## kennybobby (Aug 10, 2012)

And here it is again using fat lines to indicate that there is uncertainty in the basic data used to make the calculations.

For example how well do we know the motor torque and speed for a given voltage and current? What is the stall torque of the motor, and how long can it be held there? You need a proper motor datasheet that identifies motor parameters and gives a range +/- of uncertainty, 5%, 10%, whatever it is. 

If you are a serious buyer, then they should treat you that way and give you some serious motor data.

Before spending money to buy this motor, you should ask them to give you some real dynamometer test data, including thermal measurements, for whatever voltage and current you think you might use. This should be a spreadsheet of real test results, not some cartoon graph that was drawn for a sales brochure. You need to see some proof that it will perform at the power level you desire without melting down--let them put their money where their mouth is; if they say it will do it, then they should prove it.

The uncertainty of the aerodynamics is another big concern when making guesstimates on performance. but that will have to a a topic for another night...


----------



## tropes (Jul 24, 2011)

kennybobby said:


> you should ask them to give you some real dynamometer test data, including thermal measurements, for whatever voltage and current you think you might use. This should be a spreadsheet of real test results, not some cartoon graph that was drawn for a sales brochure. You need to see some proof that it will perform at the power level you desire without melting down--let them put their money where their mouth is; if they say it will do it, then they should prove it.


These folks appear to have considerable knowledge of the Yasa 400 motor. https://driveeo.com/
My Latvian is a bit lacking but I will attempt to contact them.


----------



## brian_ (Feb 7, 2017)

tropes said:


> These folks appear to have considerable knowledge of the Yasa 400 motor.
> https://driveeo.com/


They seem to like to stack YASA 400 motors to reach the desired power, listing the output power as 170 kW and 360 Nm per motor at 700 volts.

It seems strange to me to stack a bunch of motors together then split their power output through a differential, instead of driving each wheel with separate motors and actively controlling torque distribution. I can see it as a way to get the power through one multi-speed transmission, but it makes little sense to me with single-ratio gearing. They may just want to be able to rapidly change gearing to suit the track with quick-change final drives, and find that more practical with two final drive units (front and rear) instead of four (one per wheel). Of course, this is irrelevant to a dragster which has the two driven wheels connected without a differential.

In their Twitter feed I notied a link to some photos of a European electric dragster, with one showing that it's possible to make half a dozen YASA 400 motors look like a V6 engine - see image. 



tropes said:


> My Latvian is a bit lacking but I will attempt to contact them.


It can't be any worse than mine! 
Fortunately, most of the world is better in English than we are in anything else, so you should be okay. 

One challenge might be that their business is to sell their services, and so any more detailed motor data produced by their work may be available for purchase... but there's no reason for them to give it away. I agree with kennybobby: the motor manufacturer should provide this data.


----------



## tropes (Jul 24, 2011)

brian_ said:


> In their Twitter feed I notied a link to some photos of a European electric dragster, with one showing that it's possible to make half a dozen YASA 400 motors look like a V6 engine - see image.


The image link doesn't work


----------



## brian_ (Feb 7, 2017)

tropes said:


> The image link doesn't work


Sorry, some extra junk was pasted in accidentally; it's fixed now.


> ...
> see image.


----------



## Karter2 (Nov 17, 2011)

Dont forget the Drayson B12 world EV speed record car which used multiple Yasa motors (8?) driving all 4 wheels 
https://chargedevs.com/newswire/a-nice-long-look-at-the-drayson-b1269ev/


----------



## tropes (Jul 24, 2011)

None of these images and videos are unfamiliar to me. They are, in part, why I have suggested the use of a Yasa motor. However, as kennybobby has pointed out, we must have real data and specs to apply to this project of building a superior Jr Comp dragster.


----------



## tropes (Jul 24, 2011)

I received this email from Kristaps Dambis at https://driveeo.com/ 
I hope this is helpful and that kennybobby will provide the response. 

"Hello Peter, 
In a liquid cooled system comprising of YASA motor and eO inverter, the peak torque duration will be limited by stator thermals.
It can sustain ~450 Arms for ~30 seconds which should be more than adequate for your application.
Can you please share your intended drive cycle - motor torque and motor speed vs time?
We only have track and dyno data at ~700 Vdc system voltage but it is still largely relevant to you.

Kind regards,
Kristaps Dambis"


----------



## kennybobby (Aug 10, 2012)

Their race car builds are quite impressive. i drive a mitsubishi miev and never knew they raced one at pikes peak in 2014, but i see where the 7-stack motor has blown the record away. If they can survive 9 minutes of pikes peak, then they will survive 1/8th mile drag races.

So these Yasa motors have a racing heritage, which is great--i had never heard of them before now. But i have seen folks selling motors that had no test data, and turns out they were scams.

i will write something up to try to answer his questions and post it here for review, but probably won't get to it until the weekend.

So i'm thinking you could run a Yasa at 450 Amps with cooling and adjust the weight with ballast as needed to keep from breaking out at 6.9. The aero and friction loads are going to be whatever they will be--they can be measured later when the car is built.

You obviously did your homework on this and have the bases covered. 

Now you just need to find or build a 450A 3-phase variable frequency inverter to drive the motor.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i will write something up to try to answer his questions and post it here for review, but probably won't get to it until the weekend.


Thanks. I will reply to the email after you post the requested information. 
Hopefully someone will benefit from our R&D work.


----------



## kennybobby (Aug 10, 2012)

Okay here is an attempt to answer his question. Not sure how much detail to add at this time, maybe he will take a look and come back with more questions: 


Here is a typical motor torque and speed time history that we find when we do calculations to estimate aero- and friction-loaded vehicle performance.

It is based upon a visual reading of the torque-speed chart found on the website for the Yasa400 motor at 400 Volts and 400 Amps.

The top-level performance target is for a ~700-900 lb vehicle to travel 660 ft in 6.9 seconds at a terminal speed of 110 mph.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is a typical motor torque and speed time history that we find when we do calculations to estimate aero- and friction-loaded vehicle performance.
> 
> It is based upon a visual reading of the torque-speed chart found on the website for the Yasa400 motor at 400 Volts and 400 Amps.
> 
> The top-level performance target is for a ~700-900 lb vehicle to travel 660 ft in 6.9 seconds at a terminal speed of 110 mph.


I will send this to Kristaps. 

He says in his email today "_Let me know the target drive cycle and I will be able to comment on the potential motor / inverter performance and provide some data._"
I prefer to have a locally built inverter and driver board but this is part of the email I received from him today: http://www.lightswitchracing.com/eO1000.pdf


----------



## major (Apr 4, 2008)

kennybobby said:


> ...
> 
> Here is a typical motor torque and speed time history that we find when we do calculations to estimate aero- and friction-loaded vehicle performance.
> 
> ...


Hi kenbob,

Something doesn't strike me right about your graph. Are the 400 V & 400 A battery parameters (DC input to inverter)? So at like 2.3 seconds you hit base RPM, 2500. At 250 lb.ft. output is ~90 kW. Yet input is 160 kW? 

major


----------



## tropes (Jul 24, 2011)

major said:


> Hi kenbob,
> 
> Something doesn't strike me right about your graph. Are the 400 V & 400 A battery parameters (DC input to inverter)? So at like 2.3 seconds you hit base RPM, 2500. At 250 lb.ft. output is ~90 kW. Yet input is 160 kW?
> 
> major


Kennybobby said, "i will write something up to try to answer his questions and post it here for review"
That's exactly what must happen. 
I encourage all in this group to look carefully and review this chart.


----------



## brian_ (Feb 7, 2017)

Full points to Drive eO for a helpful response.  They sound like good people.


----------



## kennybobby (Aug 10, 2012)

major said:


> Hi kenbob,
> 
> Something doesn't strike me right about your graph. Are the 400 V & 400 A battery parameters (DC input to inverter)? So at like 2.3 seconds you hit base RPM, 2500. At 250 lb.ft. output is ~90 kW. Yet input is 160 kW?
> 
> major


howdy major,

Thanks for taking a look and making a sanity check on this.

i'm not sure if those are intended to be the battery pack or the motor values, but for some reason i think 400 VDC is the inverter input voltage, and 400 A is the motor current. These are the parameters as used on the torque and power graph of the Yasa motor from page 3 of this thread. So please take a look and let us know what you think.

http://www.diyelectriccar.com/forums/showpost.php?p=941458&postcount=108


----------



## major (Apr 4, 2008)

kennybobby said:


> howdy major,
> 
> Thanks for taking a look and making a sanity check on this.
> 
> ...


Hi kenbob,

The speed torque numbers appear consistent between those graphs. In my experience the phase current is nearly equal to the DC at base speed. I agree, most often we see these graphs with DC voltage (battery) and phase current (AC). So it is pretty confusing. 

Not sure how to get to the bottom of it. Obviously the motor manufacturer could clear it up. When they charge such prices they should be forthcoming with data. Is this the motor Eva and Bill use? If so, maybe he'd help.

I've been a motor performance graph junkie like forever but really don't know much about this motor/design. So I've just been watching the discussion, with calculator in hand. Interesting.

major


----------



## tropes (Jul 24, 2011)

major said:


> Obviously the motor manufacturer could clear it up. When they charge such prices they should be forthcoming with data. Is this the motor Eva and Bill use? If so, maybe he'd help.


 
MPaulHolmes has had some experience with the Yasa, maybe he'd help.


----------



## kennybobby (Aug 10, 2012)

i sent a note to ask Ripperton to give an opinion on this project. 

He is the author of the most-viewed thread (ruined by greedy photophucket) on this diy forum.

http://www.diyelectriccar.com/forums/showthread.php/ripperton-electric-track-bike-41173.html

for example here is a picture of his quadstack motor that he custom designed and built for his racebike.


----------



## kennybobby (Aug 10, 2012)

i did find a bit more data on the AVID, aka EVO motors from GKN.

It appears that YASA and GKN motors are located within about a 50-mile radius of each other--i was wondering why there would be such a concentration of similarly-looking and sized axial flux motors from nearly the same neighborhood in the UK. AVID has taken over the manufacturing for GKN, and they are located up in North East UK near the coast.

Motenergy (China) make a smaller version axial flux motor, http://motenergy.com/me1115motor.html


----------



## tropes (Jul 24, 2011)

Both graphs sent to Kristaps with the following:

"_We are assuming that 400 __VDC is the inverter input voltage, and 400 A is the motor current."_

I'm sure he will correct if this is not the case and as he said, 
"_I will be able to comment on the potential motor / inverter performance and provide some data_".


----------



## RIPPERTON (Jan 26, 2010)

Im onto it but Il have to read all 19 pages.
I agree with the SPM approach although I would go to 700v with a Rinehart PM150. 700v systems are impractical so dont lend well to mass production which is why Im also looking at 400v/400A. Dragsters wont ever be mass produced so its ok to look at an impractical battery voltage.
Correct me if Im wrong but with SPM my vague understanding is voltage equals torque and current just heats thing up. Its just there to prop up the math equation of Voltage x Current = kW
Brushed motors seem to be more Current biased and voltage just fry's brushes. They are very maintenance intensive because every run is a plasma event and that could mean a new commutator as well as brushes.

Tropes, have you already purchased any equipment for this project ?


----------



## brian_ (Feb 7, 2017)

RIPPERTON said:


> Correct me if Im wrong but with SPM my vague understanding is voltage equals torque and current just heats thing up


For a given speed, torque is proportional to current, because torque is proportional to magnetic field strength, which is proportional to current. That's why at low speeds AC synchronous permanent magnet motors have constant current (independent of speed), limited by the motor/inverter/controller's current limit.

Voltage overcomes back-EMF, so it is speed-dependent, and current-dependent. To get more torque you need more current, but to get more current you need more voltage (for any given speed).

The mechanical power developed is the product of torque and speed, and so it the product of current and voltage; the electrical power consumed is of course the product of current and voltage (accounting for power factor in the case of AC power). Above the current-limited speed, typical AC PM motors and inverter systems (designed for continuous power) have constant power output (independent of speed); as speed increases, more voltage is required and so less current is driven through the motor, so torque drops in proportion to speed for constant mechanical power.



RIPPERTON said:


> Its just there to prop up the math equation of Voltage x Current = kW


Math describes reality; reality doesn't care about math. 
So for a given amount of power, if you know either current or voltage, you know what the other one (current or voltage) must be... the equation says that because reality works that way.



RIPPERTON said:


> Brushed motors seem to be more Current biased and voltage just fry's brushes.


The relevant part of brushed DC motors is the extra field winding (the rotor winding corresponds to an AC motor's stator). The field winding is in series with the rotor winding in the "forklift" motors commonly used in EVs; it gets the same current as the rotor winding, but requires additional voltage, complicating the relationship of voltage, current, and speed. Still, current determines magnetic field strength and thus torque.


----------



## tropes (Jul 24, 2011)

RIPPERTON said:


> Tropes, have you already purchased any equipment for this project ?


No. My racing days left when I had 5 bones in my spinal column removed. I did turn a lot of money into noise for a few years but since my surgery I have designed and built an electric Junior Dragster for a couple of kids. I was hoping to do the same for someone who wanted to drive an electric Junior Comp car.


----------



## RIPPERTON (Jan 26, 2010)

> I did turn a lot of money into noise


= you raced ICE dragsters ?

So Brian, is there any advantage in a 700v system versus a 400v system of equal kW or would the lesser current of the 700v system result in slower accel off the mark.


----------



## tropes (Jul 24, 2011)

RIPPERTON said:


> = you raced ICE dragsters ?


Yes, but that was in my younger foolish days (1963-1985).

Now, regarding kennybobby's graph, your opinion please.


----------



## major (Apr 4, 2008)

tropes said:


> Now, regarding kennybobby's graph, your opinion please.


There is inconsistency between the values represented by the speed and torque lines (motor output) and the stated input of 400 Vdc and 400 Arms. KB's graph does represent accurately the data found here: http://www.yasamotors.com/products/yasa-400/

Yasa's information on their efficiency map (link found on the above web page) shows about 80% at the peak power (90 kW) 2500 RPM point. Calculations from KB's graph indicates much worse (using estimated battery current).

Frankly, if there is some validity in my observations, the Yasa 400 may not be a wise choice for this application.

My opinions,

major


----------



## tropes (Jul 24, 2011)

brian_ said:


> So, is the conclusion that a suitable combination of components is available, and can be reasonably expected to produce performance at the class limits, so it's time to proceed with detailed design... and tune performance with gearing and controller limits later?


After discussion with retired chassis builder it appears that I have over-estimated the weight of the rolling chassis by 60 to 70 lbs.. According to his numbers the car will not weigh more than 500 lbs without suited driver. To achieve a final weight of 700 lbs. the driver must weigh at least 200 lbs.or more weight must be added to the car.








Jr Comp frame and chassis certified to SFI Spec 2.7 B
The 22” wide rollcage certified to SFI specification 2.7C.


----------



## kennybobby (Aug 10, 2012)

Just to help show the performance envelope here is another time history that resulted when we used the 500V 450A curves from Yasa with a 755lb vehicle, but without the aero and drag loads.


----------



## tropes (Jul 24, 2011)

major said:


> Frankly, if there is some validity in my observations, the Yasa 400 may not be a wise choice for this application.
> 
> My opinions,
> 
> major


Do you have a suitable motor in mind?


----------



## brian_ (Feb 7, 2017)

RIPPERTON said:


> So Brian, is there any advantage in a 700v system versus a 400v system of equal kW or would the lesser current of the 700v system result in slower accel off the mark.


Off the mark, you are limited by current. If you want to run higher current you can, given an inverter which can handle it and enough voltage to drive it (and 700 V could certainly drive more current than 400 V), but whatever drove the choice of the current (and therefore torque) limit still applies.

If you reconfigure the battery for higher voltage and less current, and the battery becomes (or already is) the limiting factor for current, then yes you'll lose initial acceleration (which will affect ET more than trap speed). With equal power limits, that means that the higher voltage provides no performance advantage with the same motor and gearing.

The reason to increase voltage is normally to allow use a more compact or efficient motor, or to operate at higher motor speed. Higher motor speed could allow the use of more reduction in the gearing, which in turn gives more torque to the wheels for the same motor torque. That means *if* you can maintain the same current limit and run higher voltage and peak motor speed, you can launch harder, and still run the constant-power part the same way. This is what the operation of a typical modern production EV looks like: battery voltage is doubled to run the motor at 700 V or more, and the motor runs up to 10,000 rpm or more with lots of gearing.


----------



## brian_ (Feb 7, 2017)

major said:


> Are the 400 V & 400 A battery parameters (DC input to inverter)? So at like 2.3 seconds you hit base RPM, 2500. At 250 lb.ft. output is ~90 kW. Yet input is 160 kW?


This is straight from the YASA curves, shown in their spec sheet and at the beginning of this thread.

I hadn't noticed it earlier, but I agree that 340 Nm @ 2500 rpm is about 90 kW of motor output... nowhere near the 160 kW product of 400 amps and 400 volts.

The currents shown by YASA are labeled as RMS values in both the spec table and the graph title (so they are phase currents).
The voltages shown by YASA are labeled as DC values in both the spec table and the graph title (so they are for the DC link to the inverter).

What is the DC link voltage (given a perfect inverter) for a given RMS phase voltage in the delta-wired 3-phase motor? Sorry, I'm not up for that mental effort at the moment.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Just to help show the performance envelope here is another time history that resulted when we used the 500V 450A curves from Yasa with a 755lb vehicle, but without the aero and drag loads.


Aero and Friction drag have not been determined but the real drag racing question is: Can a 700lb car travel 660 feet in 6.9 seconds powered by a battery with this Yasa motor?


----------



## major (Apr 4, 2008)

brian_ said:


> This is straight from the YASA curves, shown in their spec sheet and at the beginning of this thread.
> 
> I hadn't noticed it earlier, but I agree that 340 Nm @ 2500 rpm is about 90 kW of motor output... nowhere near the 160 kW product of 400 amps and 400 volts.
> 
> ...


It's actually the phase to phase voltage out of the 3-phase inverter which is of interest here. The 400 Vdc bus voltage defines the absolute value of the peaks of maximum alternating signal which can be synthesized (neglecting junction drop). So the maximum for a sinewave RMS is Vdc/1.41. So a 400 V battery can be inverted to ~280 Vrms, phase to phase, regardless of what's connected to it, delta or star.

What is of concern and unclear is the relationship of Idc to the phase current or Irms, especially at maximum or current limit. Here is a link where I showed some theory about the topic. http://www.diyelectriccar.com/forums/showthread.php?t=92045 post #9. And as I mentioned, experience has shown me that at base RPM and current limit (which is maximum power), Idc (battery current) is very nearly equal to the motor phase current numerically.

If that is the case here, then input power (battery power) is 400 V * ~400 A = ~160 kW. And motor controller combined efficiency = 90 kWout / 160 kWin = ~56%. I doubt this is the actual case here, but feel it is warranted to find out what the real deal is. The difference between 56% and 75% efficiency means a 300 A battery instead of a 400 A battery. What's that worth in mass and $? 

I like all shapes and sizes of motors. I don't see an inherent advantage in the axial vs radial, disc vs cylindrical. Seems like the short length appeals to you. Maybe assign some value to that and compare to some cylindrical higher speed motors like from Tesla or Remy. Despite Rip's opinions, I think you should at least evaluate series wound DC with the likes of a Z2k. 

Regards,

major


----------



## brian_ (Feb 7, 2017)

major said:


> It's actually the phase to phase voltage out of the 3-phase inverter which is of interest here. The 400 Vdc bus voltage defines the absolute value of the peaks of maximum alternating signal which can be synthesized (neglecting junction drop). So the maximum for a sinewave RMS is Vdc/1.41. So a 400 V battery can be inverted to ~280 Vrms, phase to phase, regardless of what's connected to it, delta or star.
> 
> What is of concern and unclear is the relationship of Idc to the phase current or Irms, especially at maximum or current limit. Here is a link where I showed some theory about the topic. And as I mentioned, experience has shown me that at base RPM and current limit (which is maximum power), Idc (battery current) is very nearly equal to the motor phase current numerically.


Electrical power consumption can be calculated as

the product of DC link voltage and current
but the DC link current is not known
using major's assumption that DC link current equals AC phase RMS current, then power is 400V*400A=160kW

the product of AC phase voltage and current
but the AC phase voltage is not known (thus my question)
using major's assumption that AC phase voltage is ~280 Vrms, then power would be 400A*280V=112 kW... but wouldn't that be _per phase_?

I'll read major's link... but where's the link?


----------



## brian_ (Feb 7, 2017)

major said:


> I like all shapes and sizes of motors. I don't see an inherent advantage in the axial vs radial, disc vs cylindrical. Seems like the short length appeals to you.


I agree that there is no one inherently superior design. In this case, short motor length is valuable to enable a single-stage belt drive to the axle without the motor overhanging the side of the frame. Also, larger-diameter motors tend to be slower but produce more torque, and that also fits well with a single-stage belt drive.

Speaking of packaging... tropes, would a longer (and smaller diameter) motor be allowed to extend beyond the frame, assuming that it would be far enough from the axle to clear the tire on that side? That wouldn't be desirable aerodynamically, but a dragster's shape is a mess after the cockpit anyway.


----------



## tropes (Jul 24, 2011)

brian_ said:


> Speaking of packaging... tropes, would a longer (and smaller diameter) motor be allowed to extend beyond the frame, assuming that it would be far enough from the axle to clear the tire on that side? That wouldn't be desirable aerodynamically, but a dragster's shape is a mess after the cockpit anyway.


I have this L91-4003 Advanced DC motor and mounting plate sitting in my garage but for design reasons I choose to explore a more compact alternative. 
http://www.lightswitchracing.com/round.MOV


----------



## brian_ (Feb 7, 2017)

Okay, read the linked thread - thanks, major.  It raises two points:

Is the specified AC current is in a single phase, or "total" of three phases (which is apparently √3 the individual phase current)? If it is for only one phase, that's really bad, so I'll assume it's total.
What is the power factor? Quoting both current and voltage on the AC side without a power factor only enables the calculation of a maximum (power factor of unit) power demand, not the actual power.
Has anyone tried asking YASA for a consistent set of values: all AC with power factor, or all DC link?

I've seen specs for other motors which don't have this issue, but they tend to be for OEM complete systems of motor and inverter, quoting DC link electrical values and thus both avoiding confusion and wrapping up inverter efficiency with motor efficiency. Other specs are less clear.


----------



## brian_ (Feb 7, 2017)

tropes said:


> I have this L91-4003 Advanced DC motor and mounting plate sitting in my garage but for design reasons I choose to explore a more compact alternative. http://www.lightswitchracing.com/round.MOV


I recognize that earlier two-stage drive, in which the intermediate shaft carries power from the outboard first stage to the inboard second stage. But could you use just one stage which would place the motor output inboard and leave the other end of the motor hanging off to one side?

Just exploring the question of the range of possible motor options available.


----------



## tropes (Jul 24, 2011)

brian_ said:


> I recognize that earlier two-stage drive, in which the intermediate shaft carries power from the outboard first stage to the inboard second stage. But could you use just one stage which would place the motor output inboard and leave the other end of the motor hanging off to one side?
> 
> Just exploring the question of the range of possible motor options available.


The jackshaft is necessary to keep the 82 lb. motor balanced and from hanging over the frame. I will consider possible options but only after this Yasa option is fully explored. I can only focus on one at a time. 
I am hoping the guys at DriveEO will clear up a few things for us when they get home from church.


----------



## major (Apr 4, 2008)

brian_ said:


> Okay, read the linked thread - thanks, major.  It raises two points:
> 
> Is the specified AC current is in a single phase, or "total" of three phases (which is apparently √3 the individual phase current)? If it is for only one phase, that's really bad, so I'll assume it's total.
> What is the power factor? Quoting both current and voltage on the AC side without a power factor only enables the calculation of a maximum (power factor of unit) power demand, not the actual power.
> ...


It is phase current. There is no such parameter as "total". The three phase currents are assumed equal and out of phase to each other by 120°. √3 factors into power calculations which is for the whole three phase system.

The power factor value is unknown. It is rarely given or specified for non mains powered motors. For battery powered AC motors, efficiency is almost always stated, specified or measured from the DC input to the shaft mechanical power output, which is really what is needed in most cases. As can be seen by this example, having the DC voltage and phase current leads to confusion. 

major


----------



## tropes (Jul 24, 2011)

major said:


> Yasa's information on their efficiency map (link found on the above web page) shows about 80% at the peak power (90 kW) 2500 RPM point. Calculations from KB's graph indicates much worse (using estimated battery current).
> 
> Frankly, if there is some validity in my observations, the Yasa 400 may not be a wise choice for this application.
> 
> ...


Since I value your opinion and you are uncertain if this Yasa motor is capable of doing the job, what data is needed to determine whether it is? Please be specific so I am able to ask the right questions of the manufacturer by copying and pasting to an email.


----------



## major (Apr 4, 2008)

tropes said:


>


For starters, the DC voltage and inverter input current traces are needed on this graph. Work to do after that: 
> double check / verify that that graphed output will yield desired vehicle performance.
> find a controller capable of the task.
> specify and source appropriate battery.

Keep in mind that things like current ramp and battery droop will affect motor output performance so as each component is defined, the vehicle calculated ET needs be revisited. Also I am unclear as to the status of vehicle aero drag and rolling resistance in KB's simulations. 

That's about all I got for now. 

major


----------



## tropes (Jul 24, 2011)

major said:


> For starters, the DC voltage and inverter input current traces are needed on this graph.
> major


Thanks. That's a start.


----------



## kennybobby (Aug 10, 2012)

The data we are using for the aero and friction load power vs speed is found in post 152. 

http://www.diyelectriccar.com/forums/showpost.php?p=944282&postcount=152


----------



## tropes (Jul 24, 2011)

kennybobby said:


> The data we are using for the aero and friction load power vs speed is found in post 152.
> 
> http://www.diyelectriccar.com/forums/showpost.php?p=944282&postcount=152


Obviously the aerodynamic load increases but I'm still trying to figure out why the friction load increases with speed.


----------



## kennybobby (Aug 10, 2012)

Power = Force x speed; although the friction force is a constant based upon vehicle weight, the power increases as the speed.


----------



## brian_ (Feb 7, 2017)

major said:


> The power factor value is unknown. It is rarely given or specified for non mains powered motors. For battery powered AC motors, efficiency is almost always stated, specified or measured from the DC input to the shaft mechanical power output, which is really what is needed in most cases.


I get that... but if one is trying to calculate anything from AC current and voltage, then one would need the power factor.



major said:


> As can be seen by this example, having the DC voltage and phase current leads to confusion.


I agree. But if the conclusion is that nothing meaningful can be calculated from these two values (because data is missing for either approach which I listed), then why calculate anything? The motor manufacturer must simply provide the needed data to explain what appears to be a discrepancy.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Power = Force x speed; although the friction force is a constant based upon vehicle weight, the power increases as the speed.


 
I believe the arithmetic and gravity  but how does that apply to a drag strip when the first 60 feet of track are tacky and further down the track the surface is smoother and when tires start out flat but because of centrifugal force they become thin and tall?

(EDIT)
Okay, so I figured out the weight is constant regardless of the tire to surface area


----------



## Frank (Dec 6, 2008)

brian_ said:


> This is what the operation of a typical modern production EV looks like: battery voltage is doubled to run the motor at 700 V or more, and the motor runs up to 10,000 rpm or more with lots of gearing.


Hi Brian - (from an earlier post)... I think that Toyota took this approach with Gen 2 hybrids (?) but has anyone else? I would be interested in learning about high-power step-up converters if you have any information.


----------



## kennybobby (Aug 10, 2012)

tropes said:


> ...how does that apply to a drag strip when the first 60 feet of track are tacky and...


If we had some data or guesses for the high traction area, and you feel that this is a significant load, then we could use a different Crr for the first 60'.


----------



## kennybobby (Aug 10, 2012)

@ Ripperton, did you ever take your race bike to a drag strip and get some timeslips--if so would you post up some results and the weight? 

Also would you give us an overview summary of the specs of your pack and motor and controller.

Ripperton's Quad Stack is an Axial Flux Motor such as YASA and AVID are selling. 

As i recall, Daniel modified his motor to add thicker, stronger magnets (to make more torque) and re-wound it with fatter wire (allows higher current), and custom designed a liquid cooling scheme (allows more power). It seems as the Brits copied his ideas and mods--they have a larger diameter but are basically the same animal.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Daniel custom designed a liquid cooling scheme (allows more power). It seems as the Brits copied his ideas and mods--they have a larger diameter but are basically the same animal.


From my To-Do list: *Design Cooling system*
If water can be used this is what I came up with but I would like to see Ripperton's design.


----------



## Frank (Dec 6, 2008)

FWIW, I cannot believe that wheelspin will be an issue on a track with any kind of semi-decent prep.


----------



## brian_ (Feb 7, 2017)

Frank said:


> ... I think that Toyota took this approach with Gen 2 hybrids (?) but has anyone else? I would be interested in learning about high-power step-up converters if you have any information.


Yes, Toyota definitely did this, and that's who I was thinking of; I'll look for other examples. It may not be as common as I was thinking (for instance, Tesla appears not to be boosting from battery voltage), but even one case is a good example of the approach.

Sorry, I don't have any details about the step-up electronics.


----------



## brian_ (Feb 7, 2017)

About the drag load...

Although the rolling (not aero) drag is generally due to friction, it shouldn't be confused with traction. Whether the tires stick perfectly or slip substantially, there is still rolling drag absorbing energy, and that's what the rolling drag load is representing. With the power available defined as power coming from the motor, even losses in the belt drive count as rolling drag.

Perfection is traction is zero slip, so the tires transmit as much force as you want.
Perfection in rolling drag is zero force, so no energy is needed to overcome drag and keep the vehicle rolling (although of course there's still aero drag).


----------



## tropes (Jul 24, 2011)

brian_ said:


> About the drag load...
> Perfection in rolling drag is zero force, so no energy is needed to overcome drag and keep the vehicle rolling (although of course there's still aero drag).


Aero and Friction drag have not been determined but the real drag racing question is: Can a 700lb car travel 660 feet in 6.9 seconds powered by a battery with this Yasa motor?


----------



## Karter2 (Nov 17, 2011)

These"Phi-Power" AF motors are very similar to the Yasa design.
Does this data help ?
http://www.phi-power.com/wp-content/uploads/2017/04/Ph381-Specsheet-V1.3.pdf.
The Aussie contact for these (chris Jones) has raced one in a track bike (competitor and buddy of Rippertons i believe) for a few years and has a lot of data
https://endless-sphere.com/forums/viewtopic.php?f=31&t=90879&p=1348650#p1348650


----------



## tropes (Jul 24, 2011)

Karter2 said:


> These"Phi-Power" AF motors are very similar to the Yasa design.


Thanks. I was considering that motor but couldn't get any more data from them.
http://www.diyelectriccar.com/forums/showpost.php?p=943466&postcount=146


----------



## Karter2 (Nov 17, 2011)

Im pretty sure the Phi-power motors are different manufacturer to Avid.
Phi power are a Swiss manufacturer.


----------



## jonescg (Nov 3, 2010)

Hey guys,

Yeah, Phi-Power motors are a different motor to the Evo motor in that they are wound slightly differently, as well as a lighter, reinforced rotor so they spin faster. They are a bit lighter too. They just happen to use the same shaft spline and bolt-hole pattern.

Avid are selling Evo motors again, and so far as I can tell they haven't made any advances in weight or power/torque, but great that they are available again.

I think the Evo AFM140 and the PhE381 are very comparable motors, with the PhE381 being 4 kg lighter and spinning up to 6000 rpm instead of 5000. We put Voltron (AFM140-4) on the dragstrip and pulled a 9.92 quarter mile, if that's a useful metric to go by.


----------



## tropes (Jul 24, 2011)

jonescg said:


> I think the Evo AFM140 and the PhE381 are very comparable motors, with the PhE381 being 4 kg lighter and spinning up to 6000 rpm instead of 5000. We put Voltron (AFM140-4) on the dragstrip and pulled a 9.92 quarter mile, if that's a useful metric to go by.


Performance data graph is for 650 V DC and 400 A rms max line current. Can this data be extrapolated for 400V dc and 400 A?
http://www.phi-power.com/wp-content/uploads/2017/04/Ph381-Specsheet-V1.3.pdf


----------



## kennybobby (Aug 10, 2012)

jonescg said:


> ... We put Voltron (AFM140-4) on the dragstrip and pulled a 9.92 quarter mile, if that's a useful metric to go by.


Howdy Chris, yes that is quite useful--would you happen to have the total weight, rear tire size, and sprocket ratio that you used for that run?


----------



## kennybobby (Aug 10, 2012)

We can take a look. Just today i used the AF130-3Turn motor constant data to create this torque and power chart for 350VDC pack and motor current of 430 A rms, based upon the GKN EVO datasheet. Metric torque 350 N-m equates to 258 ft-lbs.


----------



## jonescg (Nov 3, 2010)

Sure - bike total mass is 214 kg, 17" tyres (180/55 at the time) and the ratio was 20 front, 37 rear.

I don't know if you can do a comparison on a 400 V bus unless you assume the same winding configuration. The 4-turn motor is listed in the datasheet, but if you were to run a lower DC bus and push more amps, I'd say the 3-turn motor might be the better option.


----------



## kennybobby (Aug 10, 2012)

Thanks Chris, i can use that to compare with the dragster predictions.

@Peter, you hit the mother lode--finally found some decent motor parameters in that last data sheet.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> @Peter, you hit the mother lode--finally found some decent motor parameters in that last data sheet.


Certainly looks like a mother lode to me.


----------



## kennybobby (Aug 10, 2012)

Here is a copy of the published 20sec motor torque and power curve for the PH381 from their pdf.

i thought i would try to duplicate their results using the table of motor winding parameters, but could not get the power to ramp up to 200kW at 5k RPM such as is shown for the 20 sec max curves. i could get the Base speed with full torque out to 1000 RPM. Any ideas why the power keeps going up after base speed?


----------



## jonescg (Nov 3, 2010)

The dyno plot on our bike shows power dropping off after a maximum:




There's some battery sag there too, which wouldn't be evidenced on the data chart.


----------



## major (Apr 4, 2008)

kennybobby said:


> Here is a copy of the published 20sec motor torque and power curve for the PH381 from their pdf.
> 
> i thought i would try to duplicate their results using the table of motor winding parameters, but could not get the power to ramp up to 200kW at 5k RPM such as is shown for the 20 sec max curves. i could get the Base speed with full torque out to 1000 RPM. Any ideas why the power keeps going up after base speed?


Hi kenbob,

The 20 second curve is a thermal rating curve, not a peak performance plot showing base RPM where torque starts to fall. On this curve the current below 4700 RPM is less than 400 A. 

If I'm right about that, then higher torque may be possible at low speeds for durations less than 20 seconds.

Regards,

major


----------



## tropes (Jul 24, 2011)

jonescg said:


> Sure - bike total mass is 214 kg, 17" tyres (180/55 at the time) and the ratio was 20 front, 37 rear.
> 
> I don't know if you can do a comparison on a 400 V bus unless you assume the same winding configuration. The 4-turn motor is listed in the datasheet, but if you were to run a lower DC bus and push more amps, I'd say the 3-turn motor might be the better option.


Does the 471 lbs include the weight of the driver? Do you think the EVO-AFm140 with 400V battery would drive a 700lb car 660ft in 6.9 sec? What cooling system did you use for motor and inverter?


----------



## jonescg (Nov 3, 2010)

tropes said:


> Does the 471 lbs include the weight of the driver? Do you think the EVO-AFm140 with 400V battery would drive a 700lb car 660ft in 6.9 sec? What cooling system did you use for motor and inverter?


Pottz weighed about 80 kg (at the time  ) so the total mass was 294 kg.

I think those numbers sound about right - the 400 V battery would require the 3-turn motor in order to get the best out of it. We passed water through the motor and inverter (series loop) and a fairly modest radiator. You could easily prime it with ice water if you really wanted to hotrod it.


----------



## tropes (Jul 24, 2011)

jonescg said:


> Pottz weighed about 80 kg (at the time  ) so the total mass was 294 kg.
> 
> I think those numbers sound about right - the 400 V battery would require the 3-turn motor in order to get the best out of it. We passed water through the motor and inverter (series loop) and a fairly modest radiator. You could easily prime it with ice water if you really wanted to hotrod it.


Thanks. I'm a bit concerned about the diameter of the motor. To use the Gates belt and the ratio the C-C of drive and driver cannot exceed 13 inches. With a 10 inch brake rotor and a 15" motor there is little room for adjustment.


----------



## tropes (Jul 24, 2011)

I think I can get the weight down to 650 lbs. The goal is to run a 1/8 mile in 6.9. Your gear ratio is different but the 9.92 quarter mile time slip should show a 660 ft time.


----------



## tropes (Jul 24, 2011)

Received from DriveEO

"YASA-400 motors http://www.yasamotors.com/products/yasa-400/ were pre-production and are essentially not manufactured any more. You can only acquire some old stock from somebody like ourselves.

Instead you should be looking at the production version P400 http://www.yasamotors.com/products/p400_series/

In either case the motor can sustain 450 Arms phase current for about 30 seconds, provided the controller can supply it.
So as a first step I suggest working off this graph here http://www.yasamotors.com/wp-content/uploads/2015/09/YASA_P400_Product_Sheet.pdf
There is a 400 Vdc curve and I recommend this tool for reading data points off the graph https://automeris.io/WebPlotDigitizer/

This will give you slightly more torque and power than you were previously considering."


----------



## jonescg (Nov 3, 2010)

tropes said:


> I think I can get the weight down to 650 lbs. The goal is to run a 1/8 mile in 6.9. Your gear ratio is different but the 9.92 quarter mile time slip should show a 660 ft time.












Elapsed Time 9.978
Terminal Speed 238.32 km/h
Reaction Time 0.188
60' 1.825
330' 4.628
660' 6.734
660' speed 193.38 km/h
1000' 8.476

We went a smidge quicker on our best run giving an ET 9.92 @ 240 km/h


----------



## kennybobby (Aug 10, 2012)

tropes said:


> Received from DriveEO
> 
> ...
> There is a 400 Vdc curve and I recommend this tool for reading data points off the graph https://automeris.io/WebPlotDigitizer/


Bonus points to DriveEO for sharing--that is a great tool, i had no idea such existed...


----------



## kennybobby (Aug 10, 2012)

major said:


> ...The 20 second curve is a thermal rating curve, not a peak performance plot showing base RPM where torque starts to fall. On this curve the current below 4700 RPM is less than 400 A.
> 
> If I'm right about that, then higher torque may be possible at low speeds for durations less than 20 seconds.


Howdy major,

What you said makes sense and i think you are right. Here is a plot of Kt for the Phi381. For the 6T winding it only takes 231 Amps to make 640 N-m. Of course they were using 650V and could make the higher speed--i don't think 400V will be enough if using the 3T winding.


----------



## kennybobby (Aug 10, 2012)

Here is the Ke chart showing RPM vs voltage for the Phi 381 parameters.

It almost appears like they used the 6T Kt and the 3T Ke to generate the torque and power curve for the 650V 400A graph on the datasheet..?

650V with the 6T winding would seem to be limited to under 4000 RPM according to their motor parameters. What am i missing here?


----------



## jonescg (Nov 3, 2010)

kennybobby said:


> 650V with the 6T winding would seem to be limited to under 4000 RPM according to their motor parameters. What am i missing here?


Field weakening. After 4000 rpm the inverter trades torque for speed - it still spins up to 6000 rpm but the acceleration drops off.


----------



## major (Apr 4, 2008)

jonescg said:


> Field weakening. After 4000 rpm the inverter trades torque for speed - it still spins up to 6000 rpm but the acceleration drops off.


Good call. Agreed. Looks like ~4000 is base for that voltage.

major


----------



## tropes (Jul 24, 2011)

jonescg said:


> Elapsed Time 9.978
> Terminal Speed 238.32 km/h
> Reaction Time 0.188
> 60' 1.825
> ...


I'm impressed. Your motor-battery combination seems to be right for our project.
If Pottz has a younger sister who weighs 50 lbs less, she would be the ideal driver for a Jr Comp car.


----------



## kennybobby (Aug 10, 2012)

Is field weakening possible in a PM motor? 

Once the back emf equals the buss voltage (max inverter output) it would seem there is no way to increase speed. 

i'm assuming the Ke is equal to the back emf constant.


----------



## major (Apr 4, 2008)

kennybobby said:


> Is field weakening possible in a PM motor?
> 
> Once the back emf equals the buss voltage (max inverter output) it would seem there is no way to increase speed.
> 
> i'm assuming the Ke is equal to the back emf constant.


Hi kenbob,

Yep. Several ways to do it. Most likely they alter the commutation angle or shift the applied voltage relative to rotor position. This effectively reduces the net flux thru the armature coil. Similar to advancing brushes on a DC motor.

major


----------



## tropes (Jul 24, 2011)

major said:


> Hi kenbob,
> 
> Yep. Several ways to do it. Most likely they alter the commutation angle or shift the applied voltage relative to rotor position. This effectively reduces the net flux thru the armature coil. Similar to advancing brushes on a DC motor.


hi major
thanks for putting it terms I can understand.


----------



## kennybobby (Aug 10, 2012)

Here's an attempt to predict Chris Jones' Voltron racebike performance at the 1/4mile dragstrip using 0.45 Cd 6sqft aero and 0.02 Crr friction loads and the P400 YASA motor. Prediction is for 9.5 sec ET at 253 kmh, which is pretty dang close for a first attempt considering all the variables involved.

This was calculated using the torque and power chart for AF140 P400 motor with 400V 450A (blue line in YASA chart). Not sure if this is the 4-Turn winding even though i marked it as such. 

The actual timeslip data that he reported is noted on the graph also.


----------



## kennybobby (Aug 10, 2012)

And here is the motor torque and RPM time history for the previous run. 

Hey Chris Jones, Did you ever get any speed radar data on a long track--it would be interesting to see what sort of top speed your bike has...


----------



## jonescg (Nov 3, 2010)

Nice simulations. We have been clocked at 255 km/h at Sydney Motorsports Park, and I really don't think there was much more in it after that, at least not with that gearing.

If you want to see field weakening in action, watch the video of Taz at Queensland Raceway. As he heads down the long back straight you can see the battery amps climb and the battery voltage drop as he approaches base speed (about 205 km/h). After this the battery current drops despite the throttle still being WOT. 
https://www.youtube.com/watch?v=qUlt_2Z1ubc&t=2s


----------



## tropes (Jul 24, 2011)

I agree, the simulations are very nice. On another topic:
Since I know so little of the construction of an inverter/controller I am asking anyone who can to tell me if there is a way to install a switch which bypasses the throttle and allows the total current to be transmitted to the motor. When closed the button would control the current; when open the throttle would control the current. I call it the Burnout Button.


----------



## jonescg (Nov 3, 2010)

tropes said:


> I agree, the simulations are very nice. On another topic:
> Since I know so little of the construction of an inverter/controller I am asking anyone who can to tell me if there is a way to install a switch which bypasses the throttle and allows the total current to be transmitted to the motor. When closed the button would control the current; when open the throttle would control the current. I call it the Burnout Button and those who have drag raced an EV know how it could be used.


It's very dangerous, but you could put a momentary switch between the wiper and 5V. But this is saving you the trouble of 100 milliseconds to snap the throttle. Otherwise, being an AC motor there is no way to avoid the inverter for making the motor spin.


----------



## tropes (Jul 24, 2011)

jonescg said:


> It's very dangerous, but you could put a momentary switch between the wiper and 5V. But this is saving you the trouble of 100 milliseconds to snap the throttle. Otherwise, being an AC motor there is no way to avoid the inverter for making the motor spin.


What throttle are you using? When I switched from a Curtis pot box to the inductive throttle I saw a much quicker response that made a difference in shocking the tires.


----------



## jonescg (Nov 3, 2010)

Just a Magura 5k throttle. Nothing flash. I think Pottz found that snatching it as fast as he could brought the front up too high, losing time. So in the end a smooth, fast roll-on was the best approach. So nice not needing to mess around with a clutch!


----------



## tropes (Jul 24, 2011)

jonescg said:


> Just a Magura 5k throttle. Nothing flash. I think Pottz found that snatching it as fast as he could brought the front up too high, losing time. So in the end a smooth, fast roll-on was the best approach. So nice not needing to mess around with a clutch!


No problem with the Junior thus our 60 ft times were 1.56 sec.
https://www.youtube.com/watch?v=fC61y0nzBoI

This is our record setting time


----------



## tropes (Jul 24, 2011)

Chris
The height of your Center of Gravity is much higher but I think the motor, battery controller set-up you used on that 9.97 run would fit perfectly in a 650 lb Jr comp car. The gear ratio could be calculated to run a 6.9 1/8th mile.


----------



## Frank (Dec 6, 2008)

tropes said:


> What throttle are you using? When I switched from a Curtis pot box to the inductive throttle I saw a much quicker response that made a difference in shocking the tires.


Was this with a zilla?


----------



## tropes (Jul 24, 2011)

Frank said:


> Was this with a zilla?


No it was a Raptor 1200 built by Peter Senkowsky. http://liionbms.com/pdf/dcp/raptor.pdf


----------



## tropes (Jul 24, 2011)

brian_ said:


> So, is the conclusion that a suitable combination of components is available, and can be reasonably expected to produce performance at the class limits, so it's time to proceed with detailed design... and tune performance with gearing and controller limits later?


I believe that a suitable combination is available using the motor, battery and inverter/controller that Chris Jones' Voltron bike had. The weight is similar, the estimated aero drag would be slightly higher and the final ratio could be adjusted using tire size and drive to driven gear ratio.


----------



## kennybobby (Aug 10, 2012)

i agree, and if i can find a used motor for sale will build one too.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i agree, and if i can find a used motor for sale will build one too.


Lightswitch Racing has committed sponsorship money for such a project but only if the Name is displayed and Peter has a hand in design.


----------



## Karter2 (Nov 17, 2011)

tropes said:


> I believe that a suitable combination is available using the motor, battery and inverter/controller that Chris Jones' Voltron bike had. ........


You would need to reconfigure the battery to reduce the weight and size.
Chris's bike runs a much higher capacity pack than you need for a drag strip.
Most likely a completely different cell choice to maximise discharge amps with low capacity.


----------



## tropes (Jul 24, 2011)

Karter2 said:


> You would need to reconfigure the battery to reduce the weight and size.
> Chris's bike runs a much higher capacity pack than you need for a drag strip.
> Most likely a completely different cell choice to maximise discharge amps with low capacity.


I think 8 modules of 200x sleeper cells about 35 lbs from http://www.ampahaulic.com/ would be a way to go.


----------



## Karter2 (Nov 17, 2011)

tropes said:


> I think 8 modules of 200x sleeper cells about 35 lbs from http://www.ampahaulic.com/ would be a way to go.


 Very possibly, but take time and as much advice as possible (J Metric, Jones, Major ,KB, etc) in configuring the optimum pack set up, as it will be a critical factor in the end performance


----------



## jonescg (Nov 3, 2010)

Yeah I'm running a 620 V nominal (700V max) battery with a PM150DZ inverter and AFM140-4 motor.

Unless there is a voltage limit imposed, I'd say a battery of near identical properties would do just fine - my battery weighs in at 54 kg, enclosure, contactors, fuses and everything. 168s,2p of 5 Ah, 20C cont 40C peak cells. If you want kit for this I'm more than happy to ship them to you, but you will need to source the cells yourself.


----------



## tropes (Jul 24, 2011)

jonescg said:


> Yeah I'm running a 620 V nominal (700V max) battery with a PM150DZ inverter and AFM140-4 motor.
> Unless there is a voltage limit imposed, I'd say a battery of near identical properties would do just fine - my battery weighs in at 54 kg, enclosure, contactors, fuses and everything. 168s,2p of 5 Ah, 20C cont 40C peak cells. If you want kit for this I'm more than happy to ship them to you, but you will need to source the cells yourself.


When I spoke to Rinehart regarding their inverter i was considering a 400V battery. Chris replied,_ "Our PM100__DXR__ is a better inverter for this application. It can handle 400V and 450Arms but only for a short time. Since you are in a short race the PM100__DXR__ is smaller, lighter, and cheaper than a PM150DX_."

Do you think we can get a 6.9 660 ft ET with 400V 450Arms if we bring the weight down?


----------



## jonescg (Nov 3, 2010)

Sure - but you will need to go for the 3-turn motor to get the most out of it.


----------



## John Metric (Feb 26, 2009)

tropes said:


> When I spoke to Rinehart regarding their inverter i was considering a 400V battery. Chris replied,_ "Our PM100__DXR__ is a better inverter for this application. It can handle 400V and 450Arms but only for a short time. Since you are in a short race the PM100__DXR__ is smaller, lighter, and cheaper than a PM150DX_."
> 
> Do you think we can get a 6.9 660 ft ET with 400V 45Arms if we bring the weight down?


The JEGS junior kit with old fashioned brushed motors has run 6.9 660ft
Their peak battery draw is 900amps and sag of about 100V. This is through the terribly inefficient brushed motor at luckily 85% efficient.
So 100V*900A = 90kW * .85 = 76kW 
and that's only a PEAK figure, somewhere they hit BEMF and it makes LESS power.

If you use an AC motor with a peak of 450Amps and a conservative SAG to 300V and use 95% efficiency = 450A*300V*.95 = 128KW! and if the little AC drive behaves like its bigger brother the kW will be nearly flat after reaching BEMF peak.

Unless you are adding several hundred pounds onto the junior, this should be way more than enough and I bet more on tap to get to 6.9 ET.


----------



## Karter2 (Nov 17, 2011)

If you run a 400v, 450 amp set up, you should be able to use a pack that is about 1/4 the weight of Chris's pack.
So about 30 lbs (14kg) of those Ampahaulic cells .?


----------



## tropes (Jul 24, 2011)

jonescg said:


> Sure - but you will need to go for the 3-turn motor to get the most out of it.


The AF-140-3 fits a little tight. How far was your C-C sprockets? Your RPM was about 4424 rpm with the AF-140. Is this the maximum?


----------



## Frank (Dec 6, 2008)

Don't forget the AC output voltage is not the same as bus voltage.


----------



## jonescg (Nov 3, 2010)

tropes said:


> The AF-140-3 fits a little tight. How far was your C-C sprockets? Your RPM was about 4424 rpm with the AF-140. Is this the maximum?


AFM140-3 is the same size as the AFM140-4 - it's just got thicker wire and one less turn per pole. The motor would still spin up to 5000 rpm with field weakening.



Frank said:


> Don't forget the AC output voltage is not the same as bus voltage.


True - but the motor voltage will always end up being slightly less than the DC bus voltage, unless a buck-boost topology is used (uncommon outside of Prius hybrids).


----------



## tropes (Jul 24, 2011)

jonescg said:


> AFM140-3 is the same size as the AFM140-4 - it's just got thicker wire and one less turn per pole. The motor would still spin up to 5000 rpm with field weakening.


Yes, but the AFM140 is 15" Diameter which leaves little room between the 10" brake rotor and the motor. I have been using 12" D motor in my design.


----------



## Frank (Dec 6, 2008)

jonescg said:


> ... motor voltage will always end up being slightly less than the DC bus voltage, unless a buck-boost topology is used (uncommon outside of Prius hybrids).


Less by a factor root-two as pointed out by major in an earlier post. Rinehart discusses this (and power output) in an older document; copy found on a vendor's site:

http://evwest.com/support/PMxxx Datasheet 01052012.pdf


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i agree, and if i can find a used motor for sale will build one too.


I have some leads on a used motor and inverter. 

This is part of the email I received from [email protected] .
_"Hello Peter, _
_YASA-400 motors were pre-production and are essentially not manufactured any more. You can only acquire some old stock from somebody like ourselves."_

*jonescg* may also have access to a used motor.

[email protected] has a Chevy Volt 111kW inverter and a control board that could be used.

A retired chassis builder in Nevada sent me this:
_"Peter I have a used chassis sitting it was a house car it has no body on it bare chassis I will sell for 3000.00 $ plus fright I can send pics"_

What is needed is a good machinist and welder to modify the frame to fit the motor.
and a young driver.


----------



## major (Apr 4, 2008)

tropes,

Be aware, tuning the controller to the motor is of the upmost importance and not a simple task. In most cases it requires the controller developer to have the motor in question available on a dynamometer for parameter adjustment. Perhaps some smart guy can do this for you with a hacked inverter from salvage but I wouldn't expect top performance. 

I'm pretty sure that Rinehart has characterized the motors used with his controllers and delivers it pre-tuned to the intended motor and application.

Disclaimer: I have no financial interest in any electric equipment company or service provider.

Regards,

major


----------



## kennybobby (Aug 10, 2012)

Thanks for the tips and leads. i have two young drivers, the machine shop and welder covered. i have an inverter, but not sure that the IGBTs are really up to the task for 500 Amps. So many projects, so little time.


----------



## tropes (Jul 24, 2011)

major said:


> tropes,
> Be aware, tuning the controller to the motor is of the upmost importance and not a simple task. In most cases it requires the controller developer to have the motor in question available on a dynamometer for parameter adjustment. Perhaps some smart guy can do this for you with a hacked inverter from salvage but I wouldn't expect top performance.


Good tip major. This from Chris at Rinehart, 
_"Our PM100DXR though is a better inverter for this application. It can handle 400V and 450Arms but only for a short time. Since you are in a short race the PM100DXR is smaller, lighter, and cheaper than a PM150DX."_


----------



## tropes (Jul 24, 2011)

jonescg said:


> I think those numbers sound about right - the 400 V battery would require the 3-turn motor in order to get the best out of it. We passed water through the motor and inverter (series loop) and a fairly modest radiator. You could easily prime it with ice water if you really wanted to hotrod it.


I have compared the Yasa, the EVO and the Phi 271 from a functional and design point of view. My first choice is the Phi271. If 400V 450Amp can drive this motor in a 650 lb car 660 feet in 6.9 seconds then I believe it is the best choice.


----------



## jonescg (Nov 3, 2010)

Yeah the Phi271 looks like a winner. As you're based in the USA you might do well to contact Phi-Power directly. I know Michael has a 4-turn motor in stock, but I forget whether or not the rotor is reinforced. That adds significant cost to the motor, but if you need the torque but not all the speed, you can get away with a slower rotor.


----------



## tropes (Jul 24, 2011)

jonescg said:


> Yeah the Phi271 looks like a winner. As you're based in the USA you might do well to contact Phi-Power directly. I know Michael has a 4-turn motor in stock, but I forget whether or not the rotor is reinforced. That adds significant cost to the motor, but if you need the torque but not all the speed, you can get away with a slower rotor.


I live in Canada and our dollar is equal to the Aussie dollar. Do you have any pricing on the Phi271 or know of any Endless-sphere members who are building EV's?


----------



## jonescg (Nov 3, 2010)

Yeah, but shipping a motor from Switzerland to Perth and then to Canada is going to be expensive. Indicative pricing is about $8000 for the Phi271, but as I said I don't know if it;s the motor with the reinforced rotor or not. Worth checking.


----------



## tropes (Jul 24, 2011)

jonescg said:


> Yeah, but shipping a motor from Switzerland to Perth and then to Canada is going to be expensive. Indicative pricing is about $8000 for the Phi271, but as I said I don't know if it;s the motor with the reinforced rotor or not. Worth checking.


Sorry I was not clear. I was correcting you on my citizenship. Endless-Sphere is a Canadian site but I am not a member and I was hoping you might know a Canadian member who was building a 4-wheel EV or have some knowledge of the Phi271 motor.


----------



## jonescg (Nov 3, 2010)

tropes said:


> Sorry I was not clear. I was correcting you on my citizenship. Endless-Sphere is a Canadian site but I am not a member and I was hoping you might know a Canadian member who was building a 4-wheel EV or have some knowledge of the Phi271 motor.


Not that I'm aware of, but I'll keep an eye out. It's an international forum, so there's plenty of knowledge to go around.


----------



## tropes (Jul 24, 2011)

jonescg said:


> Yeah the Phi271 looks like a winner. As you're based in the USA you might do well to contact Phi-Power directly. I know Michael has a 4-turn motor in stock, but I forget whether or not the rotor is reinforced. That adds significant cost to the motor, but if you need the torque but not all the speed, you can get away with a slower rotor.


I sent a message to Phi-Power re: Phi271 availability and pricing.
This is how it fits in a narrowed frame:


----------



## kennybobby (Aug 10, 2012)

After looking at the Phi271 datasheet--i like it too. In the interest of pushing the envelope to the limits i'm thinking it could produce a stall torque of 340 N-m with 800 Amps. This would generate 22kW of heat in the windings, and the question would be: for how long could it survive this thermal power level? 

i would guess that if it could survive 11kW for 60 seconds (as shown in their chart), then it might survive 7 seconds at 22kW. And it wouldn't even need to sustain that power level the whole time--it could be backed off during the run in a linear manner as drawn with solid blue line on their chart.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> After looking at the Phi271 datasheet--i like it too. In the interest of pushing the envelope to the limits i'm thinking it could produce a stall torque of 340 N-m with 800 Amps. This would generate 22kW of heat in the windings, and the question would be: for how long could it survive this thermal power level?


I believe the datasheet is for a 4-turn motor. *jonescg* says there is a 3-turn available. If this is correct, would the 3-turn be a better fit?


----------



## jonescg (Nov 3, 2010)

tropes said:


> I believe the datasheet is for a 4-turn motor. *jonescg* says there is a 3-turn available. If this is correct, would the 3-turn be a better fit?


If you want to run a 650 V battery, 4-turn will be perfect. For a 400 V battery the 3-turn will be better use of the available power. You could probably power it with a PM150DX.


----------



## major (Apr 4, 2008)

jonescg said:


> If you want to run a 650 V battery, 4-turn will be perfect. For a 400 V battery the 3-turn will be better use of the available power. You could probably power it with a PM150DX.


I recommend using the 400 V system. I think it makes more sense considering safety and cost. Also I won't be surprised to see competition regulations eventually adopted limiting equipment voltage level.


----------



## Frank (Dec 6, 2008)

major said:


> I recommend using the 400 V system. I think it makes more sense considering safety and cost. Also I won't be surprised to competition regulations eventually adopted limiting equipment voltage level.


Agreed. The PM100DXR is a good inverter at this level. Anything over 600 VDC is challenging as a lot of equipment holds a 600 volt rating.

That said, I'm going through a mental design of a 750V system...


----------



## kennybobby (Aug 10, 2012)

From looking at the Phi271 parameter table i believe that was the -5T motor graph, 350 Amps makes 245 N-m torque.

For a dragster you will never see or need 10k RPM--you might reach half that speed at the end. 

i think you will want the highest torque off the line. And the -6T motor makes the most torque: at 350 Amps it makes 294 N-m, while the -3T motor makes 147 N-m.

If you needed or wanted to spin up to 10k RPM, then you would want the -3T winding, because you could reach that speed with a 400 V pack.

Maybe Phi would provide the -3T and -6T graphs using 400 V and 350 A, then we could make a run and see which one will breakout at 6.9 sec.


----------



## tropes (Jul 24, 2011)

major said:


> I recommend using the 400 V system. I think it makes more sense considering safety and cost. Also I won't be surprised to see competition regulations eventually adopted limiting equipment voltage level.


I agree. I have just been in discussion with a group of NEDRA members regarding the NHRA clamp down on Electric Juniors. Because of the success of Electrics, there is a movement towards limiting their performance. For this project I think we should limit ourselves to 400V nominal.


----------



## tropes (Jul 24, 2011)

Received Excel spreadsheet from Phi-Power attached to email:
_"Dear Peter, _
_Thanks very much for your mail and interest in our motors._
_Could let me have more details bout the application. For this I attach a questionnaire could you fill in as much as possible please. _

_The Phi271 has a lower torque than the Yasa 400 but can spin much faster. _
_The machine has been originally designed and built for season 3 of FormulaE which has 750 __V__DC__ battery voltage._
_When would you need a motor?_
_Best regards _
_Michael"_
_For this I attach a questionnaire could you fill in as much as possible please. _
How do I post this Excel spreadsheet?
http://www.lightswitchracing.com/CCF.pdf


----------



## kennybobby (Aug 10, 2012)

you can send it to me by email, i'll send you a PM

you will need to change your profile to allow members to send you a private message

or check you LSR mail, i sent you a message there


----------



## tropes (Jul 24, 2011)

kennybobby said:


> you can send it to me by email, i'll send you a PM
> 
> you will need to change your profile to allow members to send you a private message
> 
> or check you LSR mail, i sent you a message there


I just forwarded the email from Phi with the Excel attached.


----------



## tropes (Jul 24, 2011)

dain254 said:


> .... in this application I think a person would be nuts to use anything but a roller chain for the final drive reduction... all hypothetical!


I could be nuts but in an effort to narrow the rear end of the dragster, I am contemplating the use of a chain.

tropes


----------



## kennybobby (Aug 10, 2012)

haha, i was wondering about using a chain.

What's the reason to narrow the rear--is it for safety or handling, easier to steer, or aero drag reduction?


----------



## tropes (Jul 24, 2011)

kennybobby said:


> haha, i was wondering about using a chain.
> 
> What's the reason to narrow the rear--is it for safety or handling, easier to steer, or aero drag reduction?


drag reduction, weight reduction and handling. we might want to change gear ratio. there are two "sweet spots" on a drag strip, each about 30" wide.
did you get my last email 400 VDC 450 amps


----------



## kennybobby (Aug 10, 2012)

That's interesting, i'm learning something new all the time.

i did get the message and will work on it over the next day or so, have to do some work and get the bills paid...


----------



## kennybobby (Aug 10, 2012)

Here's a start on the voltage and current based upon the sleeper cells


----------



## tropes (Jul 24, 2011)

kennybobby said:


> haha, i was wondering about using a chain.
> 
> What's the reason to narrow the rear--is it for safety or handling, easier to steer, or aero drag reduction?


Is 5 TIM (teeth in mesh) enough with the amount of torque produced? Is there a chart that I can use to determine whether an idler wheel is necessary?


----------



## tropes (Jul 24, 2011)

Received email from Rinehart:
"Our PM100DXR though is a better inverter for this application. It can handle 400V and 450Arms but only for a short time. Since you are in a short race the PM100DXR is smaller, lighter, and cheaper than a PM150DX."

Controller Model PM100DX 
DC Voltage – operating 50—400 VDC
DC Overvoltage Trip 420 VDC
Maximum DC Voltage – nonoperating
500 VDC
Motor Current Continuous 300 A
MotorCurrentPeak * 350 Arms
OutputPowerPeak (elect) * 100 kVA
DC Bus Capacitance 440 μF
Size and Volume 200 x 87 x 314
Weight 7.5 kg
Cable Gland Size M24
Minimum Conductor Size 4 AWG
Maximum Conductor Size 1 AWG
Minimum Cable O.D.** 9 mm
Maximum Cable O.D. 16.5


----------



## kennybobby (Aug 10, 2012)

tropes said:


> Is 5 TIM (teeth in mesh) enough with the amount of torque produced? Is there a chart that I can use to determine whether an idler wheel is necessary?


i talked this over with a friend who is an experienced mechanical engineer--he indicated that you would need to have the idler gear. With a fixed front sprocket location and fixed rear axle, an adjustable idler is necessary in order to take the slack out after assembly.

In addition he said there is only 1 tooth on each sprocket that is carrying the load, and the size of the chain (530, 635, etc) must be chosen based upon the load and the chain rating.


----------



## brian_ (Feb 7, 2017)

tropes said:


> Is 5 TIM (teeth in mesh) enough with the amount of torque produced?





kennybobby said:


> ...
> In addition he said there is only 1 tooth on each sprocket that is carrying the load, and the size of the chain (530, 635, etc) must be chosen based upon the load and the chain rating.


I'm not an expert in chain or belt drives, but it seems to me that with rigid chain links only the first tooth carries load, and the rest just have chain links resting between them... so this makes sense.

A toothed belt is different, because it is elastic, with each tooth in the set meshed with the gear being progressively less distorted. A friction drive (V-belt) similarly distributes drive force over the length of belt engaged with the pulley.


----------



## brian_ (Feb 7, 2017)

tropes said:


> Is there a chart that I can use to determine whether an idler wheel is necessary?





kennybobby said:


> i talked this over with a friend who is an experienced mechanical engineer--he indicated that you would need to have the idler gear. With a fixed front sprocket location and fixed rear axle, an adjustable idler is necessary in order to take the slack out after assembly.


It makes sense that there must be some way to adjust to take out slack in all but very short chains (with the sprockets nearly touching). That can be a moveable idler, or either the drive or driven end can be adjusted. I've seen all three done, but the idler seems like the easiest to implement in a robust manner.

For examples, timing chains in pushrod engines (with the driven cam low in the block, near the crank) routinely have no idler or other tensioner, while timing chains in overhead cam engines always have tensioners (usually guides with adjusters, not idlers, but they're running in an engine oil bath).

It seems to me that the thing to watch with an idler is that, while it would normally be placed on the "slack" side of the chain, it will be on the tight side of the chain during regenerative braking... and so the force on the idler can be substantial.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> i talked this over with a friend who is an experienced mechanical engineer--he indicated that you would need to have the idler gear. With a fixed front sprocket location and fixed rear axle, an adjustable idler is necessary in order to take the slack out after assembly.
> 
> In addition he said there is only 1 tooth on each sprocket that is carrying the load, and the size of the chain (530, 635, etc) must be chosen based upon the load and the chain rating.


The front sprocket is moved back after the chain is installed to take the slack out of the chain. 
I must become more educated regarding roller chain. Until then, I will stick to my original design using Gates Poly Chain Carbon belt.


----------



## kennybobby (Aug 10, 2012)

tropes said:


> The front sprocket is moved back after the chain is installed to take the slack out of the chain.


This would work if the motor with drive sprocket is free to move/adjust and lock it place--that will also have to be done with a belt. 

In the photo both the front and rear sprockets were fixed in place and not adjustable, hence the need for the idler.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> This would work if the motor with drive sprocket is free to move/adjust and lock it place--that will also have to be done with a belt.
> 
> In the photo both the front and rear sprockets were fixed in place and not adjustable, hence the need for the idler.


The slots on the top of the motor are to allow the motor to move in order to adjust the C-C drive to driven distance. This worked well with the Junior Dragster.


----------



## brian_ (Feb 7, 2017)

tropes said:


> The slots on the top of the motor are to allow the motor to move in order to adjust the C-C drive to driven distance. This worked well with the Junior Dragster.


So nothing except friction of the bolted joint keeps the motor from moving in the slots? I suppose that works for brief runs with frequent checks, but in other applications that's not a reliable tensioning method for drive chains (alternator belts - yes)

Motorcycles (and bicycles) move the driven shaft to adjust tension, and they typically use a screw or eccentric mechanism to do it. It doesn't matter which end is moved (it's easier to shift the axle in a motorcycle than the engine, and likely easier to shift the motor than the axle in the dragster), but an easily adjusted mechanism which won't creep seems preferable to me. Perhaps it's more critical in motorcycles due to their long chains.


----------



## Karter2 (Nov 17, 2011)

Poly Tooth belt drives have some well known advantages..
Low weight
Low maintenance
No lubrication
Low noise
Long life
Precision timing
Etc
.....some of which are advantageous in various applications (EG:- Blower drives)
If they have a weakness , it is low speed, high torque, transmission situations where the size and weight of the belt gets out of proportion to the situation and increases the friction losses, particularly if small pulley diameter is required.
A Dragster final drive may be such a situation where a chain is more applicable ?...JMHO


----------



## brian_ (Feb 7, 2017)

Karter2 said:


> Poly Tooth belt drives have some well known advantages..
> Low weight
> Low maintenance
> No lubrication
> ...


All of that makes sense.

On the other hand, the dragster looks a lot like a heavy motorcycle to me. While most motorcycles use chains and many use shafts, there are a lot of heavy bikes with belt drives (mostly Harley-Davidsons). While it may or may not be the optimal solution, a belt drive is at least a reasonable option.


----------



## tropes (Jul 24, 2011)

Karter2 said:


> .....some of which are advantageous in various applications (EG:- Blower drives)
> If they have a weakness , it is low speed, high torque, transmission situations where the size and weight of the belt gets out of proportion to the situation and increases the friction losses, particularly if small pulley diameter is required.
> A Dragster final drive may be such a situation where a chain is more applicable ?...JMHO


That's true in some cases but my experience has been with a small 28 tooth sprocket (less than 3" diameter) I had no problems running the same Gates Poly Chain Carbon belt for 5 years with a high torque DC motor. However, I do think it is a good idea to add a stop on the motor mount as Brian suggested.
The small sprocket is on the jackshaft: http://www.lightswitchracing.com/round.MOV


----------



## kennybobby (Aug 10, 2012)

Here is the ET and speed chart for the Phi271 motor using their data from the graph in post 292 above, http://www.diyelectriccar.com/forums/showpost.php?p=952618&postcount=292

Might have to add some weight or reduce the gear ratio slightly so it doesn't breakout below 6.9 seconds.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is the ET and speed chart for the Phi271 motor using their data from the graph in post 292 above, http://www.diyelectriccar.com/forums/showpost.php?p=952618&postcount=292
> 
> Might have to add some weight or reduce the gear ratio slightly so it doesn't breakout below 6.9 seconds.


What about reducing voltage?


----------



## kennybobby (Aug 10, 2012)

Or reduce current which makes less torque, lower acceleration, and slower speed to hit 6.9 ET. That curve was for a 350 Amps rms amplitude current, so it could be reduced to whatever level below that in order to reach the desired performance.

we only need enough voltage to make the necessary speed to finish the race, and only need enough current to make the torque to finish in 6.9 sec.

The 3-phase inverter converts the DC Buss voltage into the necessary voltage and current waveforms to drive the motor at the desired torque level.

Maybe Johannes Huebner's controller can handle these power levels:
http://www.diyelectriccar.com/forums/showthread.php?t=45909


----------



## Karter2 (Nov 17, 2011)

What about the driver using the throttle....a little less !


----------



## brian_ (Feb 7, 2017)

Karter2 said:


> What about the driver using the throttle....a little less !


Very hard to accurately repeat. I'm no drag racer, but my understanding is that an ideally set up drag car requires the driver only to launch at the appropriate time, then maintain full throttle and maintain control.


----------



## tropes (Jul 24, 2011)

brian_ said:


> Very hard to accurately repeat. I'm no drag racer, but my understanding is that an ideally set up drag car requires the driver only to launch at the appropriate time, then maintain full throttle and maintain control.


So much easier to rely on the car rather than the driver.
Teaching a driver can be challenging. This video is with a first time driver who had never driven before. https://www.youtube.com/watch?v=feT3YtNPHcY

BTW, she went on to set two NEDRA records and her reaction times were the best.


----------



## kennybobby (Aug 10, 2012)

Ouch!

i was thinking that some sort of adjustable control knob that would limit WOT power would be a good feature for beginners.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Maybe Johannes Huebner's controller can handle these power levels:
> http://www.diyelectriccar.com/forums/showthread.php?t=45909


Well you find out kennybobby and let us know.


----------



## tropes (Jul 24, 2011)

Something to consider. In a 16 car field, unless you get put on the trailer early, you will run 4 races. In the final you have about 15 minutes to return to the pits and recharge the battery. Quicker and easier to charge 100V than 400V.
I've never run more than 100V so I'm not familiar with a larger charger, BMS or generator. Could someone enlighten me.


----------



## Frank (Dec 6, 2008)

I think charge time is more a function of energy consumed than anything else. I use the smallish (2800 watt) generator in our camper (tow vehicle) to charge. The limitation is the 15A circuit breaker; this past season I rigged up an adapter that allows me to take two 115VAC inputs into the charger (PFC-30) which cuts charge time in half. I've charged up and been ready to go before some of the ICE bikes get cooled off enough to run their next pass.

BTW, typical energy consumed by my bike in an 1/8-mile pass is 300-400 watt-hrs so it's not enormous.

(Edit): forgot to add, this is with an 84S pack - ~350 volt hot off the charger


----------



## tropes (Jul 24, 2011)

Frank said:


> I think charge time is more a function of energy consumed than anything else. I use the smallish (2800 watt) generator in our camper (tow vehicle) to charge. The limitation is the 15A circuit breaker; this past season I rigged up an adapter that allows me to take two 115VAC inputs into the charger (PFC-30) which cuts charge time in half. I've charged up and been ready to go before some of the ICE bikes get cooled off enough to run their next pass.
> 
> BTW, typical energy consumed by my bike in an 1/8-mile pass is 300-400 watt-hrs so it's not enormous.
> 
> (Edit): forgot to add, this is with an 84S pack - ~350 volt hot off the charger


Got photos of this jerry-rigging? or diagram or drawing? 
That's a $3000 charger you're rigging. Does Manzanita Micro offer a similar adaptor?


----------



## Frank (Dec 6, 2008)

It's buried out in my trailer somewhere but it's not much to look at; I had to do something mid-season as I almost didn't make the call for a final one day. Basically it parallels two extension cords into a single input to the charger. This means the charge current is passing through two 15A breakers instead of one. It's a bit dodgy in that if one cord comes undone you could have exposed wiring but I generally tape the connections and make sure it's not laying around where someone can play with it. I would not advise anyone else to try this unless they are absolutely comfortable in these situations; I highly doubt there is a commercial product on the market to do the same thing. I only used the adaptor when absolutely necessary.

The camper wiring is AWG 14; if it was AWG 12 it would have a 20A breaker and I could charge quick enough (which I would do). My plan this season is to wire a special circuit for the PFC right from the generator so I don't have to mess around with extension cords.


----------



## Karter2 (Nov 17, 2011)

The ideal solution is to have 2 packs and swap batteries between runs.
Obviously that means extra cost, but it does mean you always have a spare battery pack as backup, and you are not relying on the charger or power feed to keep you in the race


----------



## brian_ (Feb 7, 2017)

tropes said:


> Quicker and easier to charge 100V than 400V.


Whether it is some current at 400 volts, or four times that current at 100 volts, I don't see a difference in charging speed or convenience. Whatever the pack voltage, the rate of charging is limited by the charging rate of an individual cell, and the total amount of power available. It's a different charger for different voltages, of course.


----------



## tropes (Jul 24, 2011)

brian_ said:


> Whether it is some current at 400 volts, or four times that current at 100 volts, I don't see a difference in charging speed or convenience. Whatever the pack voltage, the rate of charging is limited by the charging rate of an individual cell, and the total amount of power available. It's a different charger for different voltages, of course.


Thanks for the correction brian. I should have said *cheaper*. My 120V-20 amp Champion generator and Elcon charger together cost me about half of Frank's PFC-30.


----------



## brian_ (Feb 7, 2017)

tropes said:


> I should have said *cheaper*. My 120V-20 amp Champion generator and Elcon charger together cost me about half of Frank's PFC-30.


Cost is certainly a substantial factor! Any charger stepping up the higher voltage seems likely to be more expensive


----------



## tropes (Jul 24, 2011)

brian_ said:


> Cost is certainly a substantial factor!


Time to look at some numbers.

Rolling chassis (frame, body, wheels and tires, axle, brakes, steering).
New and used available. Machining is necessary with both.
Used- $6000. 
New- $13000 http://www.motivationaltubing.com/mm5/MT_%20Jr%20Comp_MiniDragster_9th.pdf 
New- Next Step Racing http://www.nextstepracingllc.com/
New-Mike Bos Chassis http://www.mikeboschassiscraft.com/
New- McGee Cams http://mcgeecams.com/jr-comp.html

machining- $1900 (based on parts and labour for our Junior modifications).

Battery. Available.

Inverter/controller. Available. Rinehart PM100DX - $5200 http://www.evwest.com/catalog/product_info.php?products_id=258

Cable and wiring.

Drive train (sprocket, belt or chain). Available. $500 http://www.pfeiferindustries.com/

Motor. Available.

Cooling system.

Accelerator.

Contactor. Albright ED402 $350 https://www.tecknowledgey.com/curtis-albright-ed402.html


Add some numbers or parts to the list if you have some.


----------



## kennybobby (Aug 10, 2012)

EVSE-battery charger

Portable generator


----------



## tropes (Jul 24, 2011)

kennybobby said:


> EVSE-battery charger
> 
> Portable generator


 
Last year Light Switch Racing was approached by a party who were interested in converting their ICE Junior Comp to electric. They backed away because of the high estimated cost of conversion.
I think anyone who is interested in building a Jr Comp dragster is already involved in the sport and realize the cost other than just a car. The trailer and the quad tow vehicle for our Junior were low budget units but still cost us over $21,000 plus a generator, BMS and charger.
We could start a list of expenses other than the car but first could we do just the car itself?


----------



## Karter2 (Nov 17, 2011)

What do you mean by " available". for the motor and battery ?


----------



## tropes (Jul 24, 2011)

Karter2 said:


> What do you mean by " available". for the motor and battery ?


There are several sources: Phi-Power http://www.phi-power.com/en/home/
DriveEO https://driveeo.com/
Avid Tech https://avidtp.com/product/evo-motors/
For motors and battery we haven't made a decision on which is best suited for this project and have no costs.


----------



## Karter2 (Nov 17, 2011)

Sorry, but i thought you were attempting to assemble a list of costs for all the necessary components , with options where appropriate, in order to estimate a working budget.


----------



## tropes (Jul 24, 2011)

Karter2 said:


> Sorry, but i thought you were attempting to assemble a list of costs for all the necessary components , with options where appropriate, in order to estimate a working budget.


No problem Karter2. My goal is to get a cost of just the car with the option of using new and used components. I'm hoping that others might source some parts or suggest alternatives.
https://onedrive.live.com/edit.aspx?resid=55D3850CAD59724!117&app=Excel&wdnd=1&wdPreviousSession=4c8558fc%2D9e29%2D414b%2D9055%2D4f023c0ffa8c


----------



## tropes (Jul 24, 2011)

Karter2 said:


> Sorry, but i thought you were attempting to assemble a list of costs for all the necessary components , with options where appropriate, in order to estimate a working budget.


I am attempting to set up a spreadsheet using options for each component with total costs. https://onedrive.live.com/edit.aspx?resid=55D3850CAD59724!117&app=Excel&wdnd=1&wdPreviousSession=4c8558fc%2D9e29%2D414b%2D9055%2D4f023c0ffa8c

If you wish to add to this list send an email to me and I will add you to the contributors.


----------



## tropes (Jul 24, 2011)

So far we have 3 Rolling Chassis and 4 Motor options with costs. All frames must be modified to fit the motor and motor mount.


----------



## tropes (Jul 24, 2011)

This option includes costs of parts submitted by manufacturers. Thanks to Michael http://www.phi-power.com/en/home/ , Kristaps https://driveeo.com/ and John http://www.lonestarevconversions.com/
The cost of home built parts are estimates and the Used Rolling Chassis is a quote plus the cost of machining and modifications plus rear tires (M&H 9x22-13).
I have invited other manufacturers to submit quotes for parts for the Hypothetical Dragster. I am hoping for a quote for a Home built Inverter.


----------



## major (Apr 4, 2008)

tropes,

I've not seen an Albright contactor rated over 96V. I typically use Kilovac or Gigavac.

major

Edit... PS... I don't think you should count on a homemade inverter. Just my opinion.


----------



## tropes (Jul 24, 2011)

major said:


> tropes,
> 
> I've not seen an Albright contactor rated over 96V. I typically use Kilovac or Gigavac.
> 
> major


Do you have cost and a link?


----------



## Frank (Dec 6, 2008)

https://www.ebay.com/itm/TE-EV200AA...274858&hash=item362a329147:g:jT0AAOSwXEdaYjMN

If you get the HAANA (I think that's it) there's feedback available to verify contact position. Good for 900VDC IIRC.


----------



## major (Apr 4, 2008)

tropes said:


> Do you have cost and a link?


Example only. Designer needs to specify flavor (specifications). 
http://www.thunderstruck-ev.com/tyco-lev200.html. At $125. Price seems typical for Kilovac and Gigavac models.


----------



## tropes (Jul 24, 2011)

major said:


> Example only. Designer needs to specify flavor (specifications).
> http://www.thunderstruck-ev.com/tyco-lev200.html. At $125. Price seems typical for Kilovac and Gigavac models.


I sent you an invitation to OneDrive. Were you able to view the Options?


----------



## kennybobby (Aug 10, 2012)

Here is an 1/8th mile ET prediction (6.4 sec) using the YASA pre-production P400 datasheet for a 660 lbs car with 3.3 gr and 22" tires, Cd of 0.45, A=6 sq ft, Crr 0.02, using the 450A torque curve at 400V (blue line in Power and Torque chart).

Also included is the motor torque and speed time history for this race.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> Here is an 1/8th mile ET prediction (6.4 sec) using the YASA pre-production P400 datasheet for a 660 lbs car with 3.3 gr and 22" tires, Cd of 0.45, A=6 sq ft, Crr 0.02, using the 450A torque curve at 400V (blue line in Power and Torque chart).


The weight (660 lb.) is based on the car plus a 140 lb. driver. Adding more weight will increase the ET to 6.9 sec. Are you able to find this weight?


----------



## kennybobby (Aug 10, 2012)

From just a quick look without running a new set of aero-friction loads, i would guess that ~750 lbs would slow ET down to the target range. 

If i were clever maybe i could write a macro to do it all in one click, but for now there are 3 spreadsheets: one for the motor torque and speed from the vendor datasheet; one for the aero drag loads based upon car speed and weight; and one for the ET calculation which (manually) merges the first two to get time and acceleration using the tire size, gear ratio, and weight.

Tire size and gear ratio can be changed in the ET spreadsheet but that will cause a change in car speed, which affects the aero-drag loads. Weight can also be changed, but this also affects the aero-drag loads and the acceleration. 

So basically any change that affects the aero-drag loads or car speed requires a new loads calculatlon for those conditions, and then another manual merge with the motor data.

So i don't have an easy or direct way to enter an ET and then calculate the corresponding weight. But maybe tomorrow i can crank it again using 750 lbs and see what it does.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> If i were clever maybe i could write a macro to do it all in one click, but for now there are 3 spreadsheets: one for the motor torque and speed from the vendor datasheet; one for the aero drag loads based upon car speed and weight; and one for the ET calculation which (manually) merges the first two to get time and acceleration using the tire size, gear ratio, and weight.


I think we are clever enough to know that is easier to add weight than to reduce it. If the ET prediction is close, I am sure the pre-production Yasa with a matching inverter is a viable option.


----------



## kennybobby (Aug 10, 2012)

i ran the 750 lbs drag loads and re-plotted the ET prediction, also included the 660 lbs curve (gray line).

How much do the gasoline cars generally weigh in this class? i suppose they use motorcycle engines and have to shift gears during the run. It would be interesting to compare the ET chart for an ICE car with the Electric. The work is mostly done, just need torque curve, gear ratios and rpm shift points to roll one up.


----------



## tropes (Jul 24, 2011)

kennybobby said:


> How much do the gasoline cars generally weigh in this class? i suppose they use motorcycle engines and have to shift gears during the run. It would be interesting to compare the ET chart for an ICE car with the Electric. The work is mostly done, just need torque curve, gear ratios and rpm shift points to roll one up.


How much do the ICE cars generally weigh in this class?
I asked two Junior Comp builders. This is their reply:

Bill Newman;Next Step Racing http://www.nextstepracingllc.com/
_"Although the basic premise of Jr Comp cars are the same, there has been a trend by some of the later builders to enter this game to build bloated over weight cars. This has resulted in a field of cars with a race ready weights ranging from low 500's to about 700 lbs. Engine weights very depending on the engine, harness and components that are included in those weights. With that being said, engine weights will run in the 150-250 lb range." _

Chris McGee; http://mcgeecams.com/jr-comp.html
_"Most of the cars were 525lb with Suzuki . I'm traveling at the moment call me next week."_

Something to consider: To quote Chris Mcgee,
*"What is unique about the Junior Comp Dragster is that once a driver earns a valid state driver's license, he or she can also drive the Junior Comp Dragster as an E.T. bracket car against drivers of any age. Drivers 16 years or older can also use this car to compete in NHRA Summit E.T. action. This means a 16 year-old can win a Junior Comp event in the morning and win an E.T. bracket race that same afternoon. Additionally, it means that a driver can continue to compete in this one car for many years - even decades. Other than licensing, there is no reason why parents can't run this car in the 1/4 mile classes either!"*


----------



## brian_ (Feb 7, 2017)

tropes said:


> Bill Newman;Next Step Racing http://www.nextstepracingllc.com/
> _"Although the basic premise of Jr Comp cars are the same, there has been a trend by some of the later builders to enter this game to build bloated over weight cars. This has resulted in a field of cars with a race ready weights ranging from low 500's to about 700 lbs. Engine weights very depending on the engine, harness and components that are included in those weights. With that being said, engine weights will run in the 150-250 lb range." _


I find it bizarre that anyone would criticize some of his competitors for building "bloated" cars that are less than 200 pounds heavier than the lightest car, and yet acknowledge in the same statement that the weight of the engine alone can vary by 100 pounds. Obviously, someone who has chosen a heavier engine will typically end up with a heavier car, and since that engine is likely also more powerful it may be a very rational choice.

The same reasoning applies for electrically powered cars.


----------



## tropes (Jul 24, 2011)

brian_ said:


> I find it bizarre that anyone would criticize some of his competitors for building "bloated" cars that are less than 200 pounds heavier than the lightest car, and yet acknowledge in the same statement that the weight of the engine alone can vary by 100 pounds.


Not sure if "bloated" cars is a criticism or an explanation but I think 355 pounds is a reasonable weight for a rolling chassis (no engine, battery, cooling system or drive train to the axle). 
These are two options with Yasa and Phi motors:









Plus another controller to consider. http://dev.iconcept.lv/wp/emobility/wp-content/uploads/2017/10/eO_A1000-1.pdf


----------



## tropes (Jul 24, 2011)

To accommodate the Yasa or the Phi a motor mount must be built and the frame must be modified to fit the motor.


----------



## tropes (Jul 24, 2011)

I suggested today that NEDRA contact IHRA to enquire about allowing EV's to race in some classes.
This is the reply from John Metric:

_"They already have a two classes _
_They are called "ET"_
_ET vehicle 7.5 and slower_
_And _
_ET motorcycle 7.5 and slower_
_These rules are in the IHRA supplemental rulebook printed each year. _
_I have talked to the head of IHRA and he said if you want to go faster than 7.5 he would approve that vehicle by vehicle and he was excited and said bring them on_."

If this is the case, 7.5 sec. 1/4 mile is 4.5 sec. 1/8th mile ET. Pretty damn quick. Rules are on page 26 http://www.ihra.com/images/IHRA_SUPPLEMENTAL_RULEBOOK_4-5-17.pdf


----------



## kennybobby (Aug 10, 2012)

Take a look at UQM motors and controllers, located in Colorado.

https://www.uqm.com/English/products/propulsion/automotive/default.aspx

The HP220 is listed at 750 N-m peak torque! that would get you down to the 4-5 second 1/8 mile


----------



## tropes (Jul 24, 2011)

tropes said:


> from John Metric:
> 
> _"They already have a two classes _
> _They are called "ET"_
> ...


This is a start but it does not allow EVs to compete with ICE cars in any class except Junior Dragster.
Hopefully they can be convinced to open Jr Comp class to EVs.


----------



## brian_ (Feb 7, 2017)

kennybobby said:


> Take a look at UQM motors and controllers, located in Colorado.
> 
> https://www.uqm.com/English/products/propulsion/automotive/default.aspx


Based on UQM's website, my guess is that they are interested only in significant OEM supply contracts (or product sales with associated integration services)... certainly not individual units to DIYers. They don't even publish detailed specs, as far as I can see.



kennybobby said:


> The HP220 is listed at 750 N-m peak torque! that would get you down to the 4-5 second 1/8 mile


Was this intended to be the PPHD220? The other large UQM motors can put out even more torque, but have lower operating speeds - it's the usual torque/speed tradeoff.

Fortunately, one source found a table of specs for the UQM motor range: New Eagle Products Wiki - EV-Components > UQM Motors
This table suggests that they have two physical sizes, all of the same length (23 cm) but two diameters:

"small" ones are 29 cm in diameter and weigh 50 kg
"large" ones are 39 cm in diameter and weigh 85 kg

While detailed data is not openly available even from this source for most of the UQM motors, they do have datasheets and some other detail... for those willing to contact their sales team and create an account.


----------



## Frank (Dec 6, 2008)

tropes said:


> This is a start but it does not allow EVs to compete with ICE cars in any class except Junior Dragster.
> Hopefully they can be convinced to open Jr Comp class to EVs.


Why do you think this is the case? Where does it preclude the use of electric motors for competition?


----------



## tropes (Jul 24, 2011)

Frank said:


> Why do you think this is the case? Where does it preclude the use of electric motors for competition?


Hopefully you are correct Frank. IHRA does not have a Jr Comp class so perhaps they do allow EV's to run with ICE cars. I will try to get further clarification.


----------



## tropes (Jul 24, 2011)

This is a body and frame available from Next Step Racing http://www.nextstepracingllc.com/page15.php
If anyone wants to build a 6 second 1/8th mile electric dragster I have all measurements and list of parts with contacts to complete the project.


----------



## tropes (Jul 24, 2011)

2 axle plates similar to the Motivational Tubing (shown) must be machined to attach the callipers and axle bearings.


----------



## tropes (Jul 24, 2011)

Motor mount for Phi381or Phi301


----------



## tropes (Jul 24, 2011)

Top rails of the frame with slots to match pins on motor mount.


----------



## tropes (Jul 24, 2011)

Frank said:


> Why do you think this is the case? Where does it preclude the use of electric motors for competition?


 
My understanding is that IHRA is allowing electrics to run in all ET classes. Consistency is the only factor in those classes.
There is no need to consider weight or horsepower. Any combination of motor and controller can be used providing all safety rules are met.
Just looking at the NEDRA records http://www.nedra.com/record_holders.html no EV except Larry McBride's bike has gone 200 MPH in the 1/4 mile. The current records might be good targets. The Jr Comp chassis would be a bit heavier to meet SFI Spec 2.5C Rear Engine Dragster - 7.49 Seconds or quicker 1/4 mile.
I suggest we use the data and material that has been collected. Using the same motor with taller tires and a gear ratio change it may be possible to better some NEDRA records.


----------



## tropes (Jul 24, 2011)

Using the MT chassis http://www.motivationaltubing.com/mm5/MT_%20Jr%20Comp_MiniDragster_9th.pdf
with 26" motorcycle drag tires, we could add a Phi 301 motor http://www.phi-power.com/en/phi-power-motor-series/ and 500V battery.
Estimated weight 750 lb. Rear axle ratio 3:1.
Could kenny run the numbers and find a 1/4 mile speed and ET?


----------



## kennybobby (Aug 10, 2012)

i'll take a look at it, hopefully get some time this weekend.

Feel free if anyone else cares to run some numbers


----------



## John Metric (Feb 26, 2009)

tropes said:


> Using the MT chassis http://www.motivationaltubing.com/mm5/MT_%20Jr%20Comp_MiniDragster_9th.pdf
> with 26" motorcycle drag tires, we could add a Phi 301 motor http://www.phi-power.com/en/phi-power-motor-series/ and 500V battery.
> Estimated weight 750 lb. Rear axle ratio 3:1.
> Could kenny run the numbers and find a 1/4 mile speed and ET?


Well, I don't do this for everybody. But since Peter is a good customer.... here are some modeling numbers for a theoretical junior comp with the Phi motor peak numbers. One time only.


----------



## tropes (Jul 24, 2011)

Thanks John. We appreciate your work.


----------



## tropes (Jul 24, 2011)

Wondering if the motor would act as a brake assist rather than using a parachute at the end of a 200 mph run.


----------



## Frank (Dec 6, 2008)

tropes said:


> Wondering if the motor would act as a brake assist rather than using a parachute at the end of a 200 mph run.



?? Of course regen will help slow you down but it can't replace a chute. Who's planning to go 200 mph anyway?


----------



## tropes (Jul 24, 2011)

Frank said:


> ?? Of course regen will help slow you down but it can't replace a chute. Who's planning to go 200 mph anyway?


Two 10" brake rotors and callipers do most of the braking but I wondered how much the motor would help. Larry McBride had no parachute when he went 201 mph.
I think kennybobby was planning on 200mph.


----------



## Frank (Dec 6, 2008)

The landspeed rule-of-thumb is that it takes 200 hp to go 200 mph so just coasting you have 200 hp worth of braking at that speed. If you set up tons of regen you can add to that but then you have the added electrical stress on the controller/motor and the risk of locking up the rear wheel over a bump or whatever.


----------



## John Metric (Feb 26, 2009)

I have found the batteries that are very good at discharge rate are pretty lousy at charge rate. or at least not any better at charging than a slow C rate cell. about 5C max, 1C or less preferred. High speed regen braking can quickly turn into a 20C to 60C charge rate, that is no go territory, don't try it. Think about charging a Tesla battery at 60C, or full charge in one minute?


----------

