# Airplane EV



## jwiger (Oct 18, 2014)

China's industrialization cause their air quality to drop quicker than in the US. It would be interesting if technology like this caused their air quality to improve quicker than the US's too.


----------



## Sunking (Aug 10, 2009)

jwiger said:


> China's industrialization cause their air quality to drop quicker than in the US. It would be interesting if technology like this caused their air quality to improve quicker than the US's too.


Impossible. From a commercial POV electric flight can never take flight. 

There are there things you cannot work around around. weight, space, and operating temps. 

On the weight side planes use Kerosene, and Kerosene has a Energy Density of 46Mj/Kg. At best a lithium battery has 0.8MJ/Kg. That means for a given amount of energy a battery would weigh 57 times more than Kerosene. 

If weight is not enough to open your eyes than volume might mean something. Kerosene has a Specific Energy Density of 37Mj/L, and Lithium 2 Mj/L. That means for a given amount of energy a Lithium battery would consume 18 times more valuable space.

Lastly we have operating temps. It is fricken cold up there. Well below 0 F. At jet cruising altitudes some -30 to -50 degrees F. Do you know what happens to battery capacity when it gets cold? Not just cold you know on the surface, but really cold at altitude. Guess what happens at altitude with some moisture like clouds. You get icing which has to be melted off with engine heat. That takes more energy. Then all those pesky passengers who demand to be warm and comfortable with fresh air and a light to read by.

Can you make a plane to fly on electric. Sure, but it would not usable in a commercial application. I fly RC planes and a really long flight is 10 minutes with 1/3 the weight in battery in a plane that could never meet minimum FAA structural requirements and cabin pressurization.


----------



## samwichse (Jan 28, 2012)

10kwh and a flight time of 90 minutes? So an average 6.7kw to the motor? In a sailplane looking airframe (designed for what, 40-50 knot cruise?).

What good is a plane with a range of 70-80 miles except as a trainer or maybe a powered glider?

Sent from my Nexus 5 using Tapatalk


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> Impossible. From a commercial POV electric flight can never take flight.


Never is a long time. There is already a trainer being sold here in the U.S.

As for long distance flight, that is of course still a long way off. But replacing $6/gallon AvGas with electricity for training flights, and replacing $30,000 engines (and all of their associated mechanically fallible accessories) with $5-10k electric motors which will last far longer than the 2,000 TBO for a Lycosaurus? Inevitable, even if they have to use a battery swap scheme between flights.



> Lastly we have operating temps. It is fricken cold up there. Well below 0 F. At jet cruising altitudes some -30 to -50 degrees F. Do you know what happens to battery capacity when it gets cold? Not just cold you know on the surface, but really cold at altitude. Guess what happens at altitude with some moisture like clouds. You get icing which has to be melted off with engine heat. That takes more energy. Then all those pesky passengers who demand to be warm and comfortable with fresh air and a light to read by.


Definitely an issue for commercial jets, not so much for general aviation.

Temps drop 3F / 1,000' of altitude. Batteries are exothermic when discharging, and will be inside the aircraft (probably with some light insulation). Will not possibly be an issue for GA, just for commercial (if we ever get the necessary energy density).



> Can you make a plane to fly on electric. Sure, but it would not usable in a commercial application. I fly RC planes and a really long flight is 10 minutes with 1/3 the weight in battery in a plane that could never meet minimum FAA structural requirements and cabin pressurization.


Yep. We are still a factor of 20x energy density away from "electric jets." That will need at least 2 "revolutionary improvements."

But, I don't think it will be necessary. Some process using solar power will eventually produce a relatively clean carbon-neutral fuel at prices below what it costs to pump oil from the ground and process it. Perhaps the Navy process will do it when solar is sufficiently cheap - and it will be a great way to store energy for off-sunlight hours energy too.

One last thought. Batteries don't need to achieve the power density of Jet A for commercial flights; just the energy density. At 36,000' of altitude, those jet engines are producing no more than 25% of maximum sea level power. Nice thing about electric power, it does not lose power with altitude.


----------



## PhantomPholly (Aug 20, 2008)

One more thought. Electric doesn't need cooling ducting, so planes can be more aerodynamic - perhaps cutting required power by as much as half. So, although we may need 20x energy density to achieve true parity, effective parity may be gained for light aircraft with less than that amount of improvement.

If Power Density improves quickly, it may also be possible to climb more quickly to the most efficient cruising altitude. True Airspeed increases roughly 2 knots per 1,000' of altitude for the same amount of power, and EV planes won't need turbochargers to reach the high teens at least and perhaps on up to 25k' (maximum allowable cruising altitude with supplemental O2 but without pressurization). Thus, cruising at FL250 instead of the typical 8,500' might yield a 32 knot / 36 mph increase in cruising speed for the same energy (provided the wind is not in your face).

Someone will crack that nut.


----------



## Sunking (Aug 10, 2009)

PhantomPholly said:


> One last thought. Batteries don't need to achieve the power density of Jet A for commercial flights; just the energy density. At 36,000' of altitude, those jet engines are producing no more than 25% of maximum sea level power. Nice thing about electric power, it does not lose power with altitude.


That might sound real good to the uninformed but does not fool me one bit. Propeller and Fan efficiency fall off the cliff at high altitude. You can improve propeller efficiency by making them mush larger and turning much slower RPM. But that is not practical, think Marine's Osprey aircraft or helicopters. 

Batteries will never have the energy density needed to be a commercial success. Sure a company can make an electric plane, but actually selling them is another story. You are right AV gas is expensive, and is why small civil aircraft are switching to less expensive diesel fuel and Jet-A (Kerosene). Today you can buy a light aircraft for pennies on the dollar. Civil aviation is pretty much a dead industry. I gave it up 10 years ago. Just too expensive.


----------



## jwiger (Oct 18, 2014)

Sunking, I absolutely agree with you regarding the commercial aviation sector. I was thinking about China's potential to utilize magnetic drive as a whole. 

Commercial aviation is more concerned about fuel burn than any other industry, mostly due to profit margins. A byproduct of that is they reduce the emissions per passenger. 

I'm thinking more about the more common modes of transportation. Specifically cars. Personal transportation is a huge factor in pollution. 

My point was that with attempts like this article's subject. I could easily see China putting more effort into electric vehicles than the US. Thus eliminating a huge factor in air pollution.


----------



## PZigouras (Jun 5, 2010)

jwiger said:


> I could easily see China putting more effort into electric vehicles than the US. Thus eliminating a huge factor in air pollution.


http://www.worldwatch.org/node/5320

Outlawing gas cars is already on the table in Beijing. They can, and will pass laws limiting their use. And since small aircraft are part of the problem (albeit a very small part), they will more than likely pass laws to encourage the use of electric aircraft. 

Give it a few years, and only hybrid and BEV will be allowed in the city. This may someday carry over to larger U.S. cities, like Los Angeles.


----------



## Hollie Maea (Dec 9, 2009)

Sunking said:


> At best a lithium battery has 0.8MJ/Kg.


I have a cell sitting on my desk with a nominal voltage of 3.6V and a capacity of 3Ah. It weighs 45 grams. That gives it a density of:

(3.6V*3Ah*3600s/h)/0.045kg = .86MJ

That's a cell. A well engineered battery pack would fall a little below 0.8. But that's available TODAY. And it's a power cell; there are energy cells that do even better. The bottom line is, this number is nowhere near the theoretical energy density of batteries. No, they'll never exactly match kerosene. But they'll get close enough (you cheated by neglecting to point out that kerosene has to be used in heat engines, which automatically cuts their energy density down to 1/4th).

No, you couldn't make a viable commercial electric plane today. But your usage of the word "never" is ridiculous.


----------



## Sunking (Aug 10, 2009)

Hollie Maea said:


> I have a cell sitting on my desk with a nominal voltage of 3.6V and a capacity of 3Ah. It weighs 45 grams. That gives it a density of:
> 
> (3.6V*3Ah*3600s/h)/0.045kg = .86MJ [?QUOTE] Thank you as you just confirmed what I said.
> 
> ...


----------



## Hollie Maea (Dec 9, 2009)

Still ignoring the heat engine factor. Neat.


----------



## Sunking (Aug 10, 2009)

Hollie Maea said:


> Still ignoring the heat engine factor. Neat.


Still trying to sell snake oil. Neat


----------



## Hollie Maea (Dec 9, 2009)

Sunking said:


> Still trying to sell snake oil. Neat


I literally don't offer a single thing for sale. Not everyone who disagrees with you is trying to scam people.


----------



## bigmotherwhale (Apr 15, 2011)

never say never, another technology could be around the corner 

You should consider it a possibility at the very least, breakthroughs have been made before.

wireless power transmission might even be developed and that would change everything.


----------



## PZigouras (Jun 5, 2010)

bigmotherwhale said:


> wireless power transmission might even be developed and that would change everything.


 I agree that breakthroughs can (and probably will) happen in battery technologies. But wireless power transmission in terms or aircraft will not happen.

Unless you choose to sacrifice wireless phone transmissions, Wi-Fi, over-the-air TV, and pretty much every airborn signal. High power wireless transmissions in the gHz range tends to scatter and disrupt everything in the area. The exception of course is short, point-to-point transfers (like the wireless EV chargers from Qualcomm).

N. Tesla had a good idea -- and it would work, for the most part -- but with today's technologies, the sacrifices would be great. People like their phones.


----------



## bigmotherwhale (Apr 15, 2011)

i dont want to go off on a tangent that might lead somewhere stupid, know one knows for sure how or if Tesla achieved what he did in regard to wireless power transmission, so it is pretty much speculation.

supposedly it wasn't even radio waves as we know it as he talked about longitudinal and transverse waves. It certainly cannot be done with radio waves which diminish with the square of the distance..... 

Using lasers is possible, and highly dangerous, but has been considered as a power source for ground to space vehicles.

I still think that there is so much we don't know it is impossible to rule things out, our science is still in its infancy, i believe we have only touched the tip of the iceberg in terms of what we know. 

as much as i hate the title! what they are doing here is powering wireless helicopters using radio or light frequency, its actually quite impressive. 

https://www.youtube.com/watch?v=ee4Ab3w2hl8


and this:

https://www.youtube.com/watch?v=sy1vqRT-vqI


----------



## Caps18 (Jun 8, 2008)

I don't think the batteries are there "yet", but I think general aviation and small aircraft are the only ones that will see electric motors anytime soon.

But, they will need 3-4 hours of flight time at 125 mph, and even more for Alaska and Canada. There will need to be a charging network like Tesla's Superchargers too.

I'm sure the weight of the batteries will throw it off, but I would like to see something like a motor glider that can shut off the engine and coast. I'm sure there is some energy calculations behind the power used gaining elevation and coasting, vs level flight in terms of distance, but I think this is the closest I will ever come to seeing a flying car in my lifetime.


----------



## PhantomPholly (Aug 20, 2008)

Sunking said:


> Hollie Maea said:
> 
> 
> > Not tomorrow, your lifetime, or your children and grandchildren lifetime. Get over it.
> ...


----------



## aeroscott (Jan 5, 2008)

With aluminum having a oxide/de oxide( battery cycle) energy of 6KWH/ lb. times 6 lbs. for a gallon of diesel/kerosene =36 KWH for the same weight as fuel (33 KWH/ gallon) but this fuel is 25%-30% efficiency, the old 707 jets were closer to 5-10% efficiency they still flew transoceanic. 
I would suggest 15KWH/ 6lbs. aluminum with carbon or better will be possible in the near 
future (exponential growth) .We should see 90%-95% efficiency in electric motors/controllers. 
with cryo cooling and switched reluctance motors.
Ic engines jets included have70-80% cooling needs, which yields paradisaic drag while the electric cooling needs 5-10% of used power.
All engines produce harmonics leading to heavier structures. Electrics produce these to lesser degree ,which can be moderated with motor control
programing.
Everything in airplanes is getting lighter,stronger and less drag with less labor.
Costs of running a $50,000,300 hp., 550 cu.in. Continental at 25 gallons/ hr. X $6.00/gallon X 2000 hrs.= 50,000 gallons and $300,000.
The big boys are burning 1000-4000 gallons / hr.for 10,000+ hrs 10,000,000 gallons per plane life span or more.


----------



## twright (Aug 20, 2013)

Here is another factor that no one has accounted for:

Air breathing engines lose power with altitude. Therefore, they have to make their engines MUCH bigger, because for every foot they go up, they lose power.

Electric motors don't care about altitude. The power you have on the ground is the same power you have at 10,000 feet.


----------



## Caps18 (Jun 8, 2008)

It is colder up at altitude, so heating might become more of a concern. Electric heat isn't all that efficient. Along with insulation that adds some weight.


----------



## Ovaltineo (Jul 18, 2013)

Interesting heated discussion, but am I missing something here? Li-Air may even exceed the energy density of fossil fuels. I wouldn't be surprised if cars and planes started using this in the next decade.


----------



## Karter2 (Nov 17, 2011)

twright said:


> Here is another factor that no one has accounted for:
> 
> Air breathing engines lose power with altitude. Therefore, they have to make their engines MUCH bigger, because for every foot they go up, they lose power.
> 
> Electric motors don't care about altitude. The power you have on the ground is the same power you have at 10,000 feet.


Not if they are turbo ICE's..
And what form of energy transfer will the electric motor use...props ?
Fossil fuelled aircraft can use jet thrust, for high altitude effectiveness,
At what altitude do props become ineffective ?
Maybe an EV powered dirigible ( airship, blimp ) for low altitude transport , will be the best short term option for electric flight


----------



## bigmotherwhale (Apr 15, 2011)

thought this could be relevant,and interesting 

http://inhabitat.com/mit-developing-ionic-wind-thrusters-as-efficient-alternative-to-jet-engines/

"they stated that ionic wind thrusters could produce 110 newtons of thrust per kilowatt, while a jet engine would produce 2 newtons per kilowatt."


----------



## PhantomPholly (Aug 20, 2008)

Karter2 said:


> Not if they are turbo ICE's..
> And what form of energy transfer will the electric motor use...props ?
> Fossil fuelled aircraft can use jet thrust, for high altitude effectiveness,
> At what altitude do props become ineffective ?
> Maybe an EV powered dirigible ( airship, blimp ) for low altitude transport , will be the best short term option for electric flight


Even turbos lose power at altitudes above 15k'. At very high altitudes, very little of the thrust of modern jets comes from "jet" propulsion; most of it comes from the enormous fans surrounding the motor (i.e. almost all of the energy generated by the "jet" is used to turn the fans and spin the compressors to maintain power). 

At 45,000' altitude 0.9 Mach is only 250 knots indicated airspeed. Since power required is the square of indicated airspeed, much less power is required for these speeds up high. That's why airliners fly so high up.

Dropping the speed even a little means greater efficiency. At 200 indicated, close to an airliner's most efficient airspeed (L/D(max)), at 45k' altitude you would see a true airspeed of around 450knots true (speed across the ground if there were no wind). Travel at 200knots indicated (at any altitude) takes only about 45% of the energy needed to fly at 300 indicated. Thus, future airliners might fly even higher than today (electric motors don't lose energy with altitude) but at lower indicated air speeds and achieve about the same velocity for half the energy.


----------



## PhantomPholly (Aug 20, 2008)

bigmotherwhale said:


> thought this could be relevant,and interesting
> 
> http://inhabitat.com/mit-developing-ionic-wind-thrusters-as-efficient-alternative-to-jet-engines/
> 
> "they stated that ionic wind thrusters could produce 110 newtons of thrust per kilowatt, while a jet engine would produce 2 newtons per kilowatt."


Awesome - and that efficiency could mean that the energy density of batteries is no longer as important as it seemed to achieving electric airliners.


----------



## bigmotherwhale (Apr 15, 2011)

takeoff is the highest power requirement and power could be transmitted to the plane over short distances, using laser microwaves etc, the use of air batteries and increase in efficiency from ionic thrusters, seems to me that this might be possible in the not so distant future, however possible and economically viable are two different things. 

now they are making small ev planes, means soon they will make a larger plane... 

climate change from persistent contrails are a real problem, if the problems with the climate get as bad as people say, then this could be the driving factor in progress, even if it is initially more expensive. 


I agree with the blimp idea, it should have been done years ago, the fear of hydrogen which is not really justified, has held us back, we could be sending fright in drone blimps, autonomously across the country without a problem, almost pollution free. that would free up our road network which would further reduce pollution.


----------



## Karter2 (Nov 17, 2011)

I am surprised to find that the record for the highest altitude propeller driven aircraft belongs to the electric powered "Pathfinder" , at 71,500 ft.
Slow...but high !


----------



## PhantomPholly (Aug 20, 2008)

bigmotherwhale said:


> thought this could be relevant,and interesting
> 
> http://inhabitat.com/mit-developing-ionic-wind-thrusters-as-efficient-alternative-to-jet-engines/
> 
> "they stated that ionic wind thrusters could produce 110 newtons of thrust per kilowatt, while a jet engine would produce 2 newtons per kilowatt."


Well bummer. I've just finished reading a LOT about ionic thrusters 

While it is true that the most efficient thruster may be hugely efficient in a particular configuration, the structure necessary to support the material and guide the airflow would be sufficiently heavy to offset most or all of the maximum thrust obtained (which would be measured in ounces, not tons). Nothing is said anywhere about what the effects of flying through rain or clouds, but I suspect either would further reduce the efficiency of the process.

It appears that for atmospheric travel these are likely to be nothing more than a scientific curiosity. In space, however, the efficiency far outweighs (pun intended) the light amount of thrust. In space a small efficient amount of thrust over time is far better than a good swift kick that costs a lot more in fuel.


----------



## ken1939 (Sep 4, 2010)

Sonex is working on an electric Home Built Aircraft based on one of their existing kits. They are also working on a single seat jet.

http://www.sonexaircraft.com/research/e-flight/electric.html


----------



## PhantomPholly (Aug 20, 2008)

ken1939 said:


> Sonex is working on an electric Home Built Aircraft based on one of their existing kits. They are also working on a single seat jet.
> 
> http://www.sonexaircraft.com/research/e-flight/electric.html


Yeah, Sonex is cheap and light weight, good platform for electric.

Personally in the market to replace my previous plane, am looking at the Cozys IIIs. Folks who built them in the 80s and 90s are finally retiring so the prices are coming down.


----------



## Hollie Maea (Dec 9, 2009)

Not sure why they are talking about Li-Poly cells. You don't need 25C (unless you are planning to do a 2 minute flight) so why go with dangerous cells in such a crucial situation?

It kind of looks like they approached this from the standpoint of "OK, here's RC components, how can we make them bigger?" I'd love to convert a plane like this, but I'm not sure they have the right approach.


----------



## PhantomPholly (Aug 20, 2008)

Whatever you would build ought to take into account the probability of replacing the pack at some point.

I wouldn't think a Sonex would be an ideal platform for conversion either because of the small allowable range of center of gravity. A canard design like Cozy would seem a better choice. It is just as efficient as the Sonex; has lots of space in both the wings and fuselage for batteries (especially if you use the back seat space and weight allotment); and could more readily add a bit more wing to compensate for the extra weight.

Still, you'd be hard-pressed to come up with a weight budget of 900lbs of batteries like in the Bolt. Allowance in the design is 300 lbs of fuel in the wings and about 400 lbs for back seat area in the Cozy IV - and that isn't especially safe for landing as it puts you right at gross with 2x 200 lb front seaters.


----------



## Hollie Maea (Dec 9, 2009)

PhantomPholly said:


> Whatever you would build ought to take into account the probability of replacing the pack at some point.
> 
> I wouldn't think a Sonex would be an ideal platform for conversion either because of the small allowable range of center of gravity. A canard design like Cozy would seem a better choice. It is just as efficient as the Sonex; has lots of space in both the wings and fuselage for batteries (especially if you use the back seat space and weight allotment); and could more readily add a bit more wing to compensate for the extra weight.
> 
> Still, you'd be hard-pressed to come up with a weight budget of 900lbs of batteries like in the Bolt. Allowance in the design is 300 lbs of fuel in the wings and about 400 lbs for back seat area in the Cozy IV - and that isn't especially safe for landing as it puts you right at gross with 2x 200 lb front seaters.


You could sort of make this work. You gain a bit from lighter motor.

The 180hp engine in the Cozy IV weighs 117 kg. Replace it with a Yasa 750 ran off a RMS PM150 (this setup has very similar torque/speed characteristics). The motor and controller combo weighs 43 kg. Of course, take out the 140 kg of fuel as well. So you are removing 257 kg and adding 43, so you could add a net of 214 kg of batteries before we "break even". Then we make it a two seater and use up another 135 kg in batteries (just under 300 lbs, so we still have enough margin for two fairly fat people). Subtract about 10 kg for liquid cooling and other misc, so we have a total battery budget of 340 kg. Battery module density of 175 Wh/kg is definitely achievable...that's 5.7 kg/kWh so dividing we could reasonably have 60 kWh.

We'll be be spending most our time cruising at 75% power, or 100kW, so we should be able to get a solid half hour of flight time. That's not great, but it would be a 100 mile range and a way to have fun just screwing around locally.


----------



## PhantomPholly (Aug 20, 2008)

Hollie Maea said:


> You could sort of make this work. You gain a bit from lighter motor.


Sorry I forgot to mention the figures above already assumed 100lbs weight savings for the motor. Gross weight for aircraft is determined by many factors, one of which is "how strong is the landing gear." Here are the plane's specs.

The Cozy IV has a useful load right at 1,000 lbs above empty weight. It holds 52 gallons of fuel in the wings @6lbs/gallon, for a "budget" of 312 lbs for the fuel in the wings - but keep in mind that any weight in the plane must come from the "budget" of 1,000 lbs useful load plus just under 300 lbs for motor plus accessories (alternator, starter, fuel system, exhaust, vacuum pump for the gyros, etc.). My expectation would be that even more than 300 lbs would be loaded in the wings as batteries tend to be heavier per cubic inch than gasoline, and because they don't "slosh" could be put into every nook and cranny.



> We'll be be spending most our time cruising at 75% power, or 100kW, so we should be able to get a solid half hour of flight time. That's not great, but it would be a 100 mile range and a way to have fun just screwing around locally.


You are forgetting that generally the first 10 minutes is at 100% power. On the other hand, after climb you could easily cut back to 50 or even 40% power so maybe you could get a whole hour before the "tank is completely dry." However, that is an extremely bad idea in a plane where a mis-calculation can spell disaster and also really bad for the pack.

Sadly, we will need better batteries for electric airplanes to become "useful."


----------



## Hollie Maea (Dec 9, 2009)

PhantomPholly said:


> Sorry I forgot to mention the figures above already assumed 100lbs weight savings for the motor.


All of my calculations were based on spec sheets I read, not from your estimates. Did I make a mistake? I added 297 lbs above stock. With 400 lbs of crew, that's still just 700 lbs. Seems like enough margin.



PhantomPholly said:


> You are forgetting that generally the first 10 minutes is at 100% power.


No, I didn't forget that. On the other hand, during descent I would think you would be well below 75%. So to some extent it averages out. I also accounted for 10 kWh of battery margin, so I think my estimations are fairly reasonable.

Again, 30 minutes of flight isn't amazing, but it's close to being something you could use casually. My battery density calculations are pretty conservative (based on a pack we built recently...we didn't use any exotic materials for weight savings, and there are some better cells that have come out since we designed it).


----------



## bigmotherwhale (Apr 15, 2011)

http://www.launchpnt.com/portfolio/transportation/halbach-electric-motor/

thought this might be relevant for you discussion

factor in some up and coming technology and have a budget like Elon and im sure it could be done.


----------



## Sunking (Aug 10, 2009)

Hollie Maea said:


> Again, 30 minutes of flight isn't amazing, but it's close to being something you could use casually. My battery density calculations are pretty conservative (based on a pack we built recently...we didn't use any exotic materials for weight savings, and there are some better cells that have come out since we designed it).


*§ 91.151 Fuel requirements for flight in VFR conditions.*

(a) No person may begin a flight in an airplane under VFR conditions unless (considering wind and forecast weather conditions) there is enough fuel to fly to the first point of intended landing and, assuming normal cruising speed—

(1) During the day, to fly after that for at least 30 minutes; or

(2) At night, to fly after that for at least 45 minutes.

Surprised Philly has not mentioned it. 

IFR is even more stringent which is what commercial pilots fly under

*§ 91.167 Fuel requirements for flight in IFR conditions.*

(a) No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to—

(1) Complete the flight to the first airport of intended landing;

(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and

(3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.

(b) Paragraph (a)(2) of this section does not apply if:

(1) Part 97 of this chapter prescribes a standard instrument approach procedure to, or a special instrument approach procedure has been issued by the Administrator to the operator for, the first airport of intended landing; and

(2) Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:

(i) For aircraft other than helicopters. For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.

(ii) For helicopters. At the estimated time of arrival and for 1 hour after the estimated time of arrival, the ceiling will be at least 1,000 feet above the airport elevation, or at least 400 feet above the lowest applicable approach minima, whichever is higher, and the visibility will be at least 2 statute miles.


----------



## Caps18 (Jun 8, 2008)

bigmotherwhale said:


> http://www.launchpnt.com/portfolio/transportation/halbach-electric-motor/
> 
> thought this might be relevant for you discussion
> 
> factor in some up and coming technology and have a budget like Elon and im sure it could be done.


That needs a silencer on it.  It also needs to be a little bit bigger. But, I agree that motors that use less energy would be a step in the right direction.

The speed of the airplane might play a role in how long it can stay afloat and how far it can travel. I would like to see a glider that is designed around being electric from the start instead of trying to convert a typical plane to be electric. I'm not sure if the physics would work, but it needs to be efficient enough to use up to 20% of the battery getting to altitude and speed, then use 20% of the battery an hour for up to 3 hours. I would hope that it could travel at 100mph (+/- head/tail wind) as well.

There would need to be a Supercharging network as well to recharge it in an hour or two as well.


----------



## PhantomPholly (Aug 20, 2008)

Hollie Maea said:


> All of my calculations were based on spec sheets I read, not from your estimates. Did I make a mistake? I added 297 lbs above stock. With 400 lbs of crew, that's still just 700 lbs. Seems like enough margin.


I'm working backwards from completed plane, and assume the same propeller. The gross weight figure includes a useful load of 1,000 lbs for fuel, people, baggage. Empty weight assumes an IO-360 plus engine accessories (about 300 lbs) plus a 40 lb lead acid battery (which you might replace with a DC-DC converter if you are brave, or at least size smaller since you don't need to turn a starter motor). For round numbers, call that a 1,350 pound "allowance." In reality this is a bit variable depending on how carefully built the airplane is - too much resin or an extra coat of paint can easily add 100 lbs, for example.

Now start deducting motor, controller, whatever size 12v battery you feel comfortable with, DC-DC converter (or alternator on the main motor if you prefer to go that path), and batteries. Whatever is left after that is what is left for people and baggage.



> No, I didn't forget that. On the other hand, during descent I would think you would be well below 75%. So to some extent it averages out. I also accounted for 10 kWh of battery margin, so I think my estimations are fairly reasonable.


Ok good. You could even get clever with regen, but that would cost miles in the descent so it's probably not worth it.



> Again, 30 minutes of flight isn't amazing, but it's close to being something you could use casually. My battery density calculations are pretty conservative (based on a pack we built recently...we didn't use any exotic materials for weight savings, and there are some better cells that have come out since we designed it).


I agree for putzing around the local area. Even more if you use low power settings. However, when comparing with the "usual" range of this plane of 1,000 miles at 75% power/ 1,300 miles at reduced power, it makes a seasoned pilot cringe. IFR with 30 minutes? Forgeddaboutit, you are below IFR reserves before you even take off.


----------

