# EV Flying Machine for the future.



## LSB (Jul 25, 2012)

I had been thinking about building a lifesize quadrotor helicopter in the vain of my little blade mqx and I had a look to see if anyone had done it, and came up with this video. The team has publicly displayed this at the 2012 German Air Show and received Lindberg award for innovation. There is a couple of other images if you search this subject, but this is the only one I know that has been built.






This design uses 16 2 kilowatt motors. I am unsure of the other specifics of the vehicle other than estimated weight at 170kgs.

I believe that this type of design would be possible in a quadrotor configuration. By lowering the centre of gravity to the intersection of the chassis arms the vehicle would be more stable. By reducing the amount of motors the chance of failure decreases.

The Quadrotor would also offer a greater propeller thrust area. There is a lot of estimation involved in calculating the specifications of downward force required for sufficient lift. After some initial consideration my proposal is as follows..

PERFORMANCE and Specification GOALS:
A quadrotor vehicle capable of 1000 feet altitude and 100knots 
48kw continuous,120kw burst 
300kg gross weight
Battery pack capable of 30ish minutes flight time (giving 80km range)
Aluminium Frame/chassis + Carbon Fibre Fuselage and Fan shrouds
Under 5meters total diameter.
Stability software for safety and easier learning curve.

Dimensions approximately 4500mm wide, 4500mm length, 1900mm height (with enclosed rotors)

Driver position would be slung below the level of the rotors with head at a level just above, keeping CoG neutral. Driver also to be enclosed in high rigidity, enclosed shell in the middle of the four rotors (aka AR drone).

Premilinary sketch of the chassis i produced on sketchup is of dodgy quality but my main computer is being rebuilt so I have no Solidworks at the moment. IThe cockpit chassis is obviously unfinished, ill get to it when i have solidwords back. It should give a vague idea though.

There is about 18 metres of aluminium there worth about $1200 and about another 18m to complete the cockpit and supports, meaning around $2500 of materials for the chassis.










The sensor required by the software to level the aircraft could be the ARM UM6-LT Orientation Sensor (IMU) Autopilot w/ Arduino. It is around $150,

For motors, I am considering a pair of these kits:









These are from kellycontrollers, they are rated 12kw continous (150a) and 30k max. Retail at $2700 meaning 5400 for chargers,motors and controllers.
The controller is a 500amp kellycontrollers unit and the motor is the Mars ME0913.

For batteries Im looking at









24 packs will be required for the 288v. Hopefully these will deliver close to half an hour of flight. Unless under unusual circumstances, the system should run at under 150 amps which should mean a good battery life. Control input would have to be perfect and I thought something like this may fit the job when modified ($200)









There will be many other parts needed, such as instruments, software, seat, fibreglass or carbon-fiber cockpit and fanshrouds etc... I was thinking of building a naked prototype, as the cockpit/fanshroud design and fabrication could well be the most espensive part of the project.

If you add the costs already calculated you can see that this is no small undertaking and without any expertise in many of the areas required to complete this project (especially electrical systems) I'm wondering about what you guys think about the viability of this....

Major Concerns would be:
The performance of self levelling software.
Total Weight. (65kg Battery pack. 80kg for motors/controllers. Frame estimate 40kg). Only leaves 115kg for everything else...
Battery Life.
Propeller material.
Cockpit rigity and crash avoidance/systems.
Pilot...Anyone keen?


----------



## Salty9 (Jul 13, 2009)

LSB said:


> The sensor required by the software to level the aircraft could be the ARM UM6-LT Orientation Sensor (IMU) Autopilot w/ Arduino. It is around $150


Have you considered the Wii Nunchuk for stability sensors? People have used them for DIY segways.

http://wiibrew.org/wiki/Wiimote/Extension_Controllers/Wii_Motion_Plus


----------



## LSB (Jul 25, 2012)

Sorry about the first picture, I really havent used sketchup for a long time, this may be a better pic to get an ideo of the design i had in mind. Its very messy and the large plates on the bottom of the props arent meant to be there...








This is without the roll bar and top part of the cockpit and has most of the chassis tubular framework removed. Also the seating position is more laid back as you can tell from the shape of the aluminium fuselage pictured...


----------



## LSB (Jul 25, 2012)

Salty9 said:


> Have you considered the Wii Nunchuk for stability sensors? People have used them for DIY segways.
> 
> http://wiibrew.org/wiki/Wiimote/Extension_Controllers/Wii_Motion_Plus


The wii sensor would sure be a cheap and reliable option. Im not sure it would have the accuracy of the chip though.. Definately worth a try for testing phase anyway..
Now that I checked the link, they are every easy to work with and will be a great tool for testing, thanks!


----------



## Salty9 (Jul 13, 2009)

Interesting project. Keep us earthbound plodders updated.


----------



## PThompson509 (Jul 9, 2009)

I've also been studying this for a while now. The reason for multiple controllers is a LOT of redundacy. Each motor has their own controller. I believe that each controller has its own battery, too, but that is overkill in my book. 

For this design, you can do well with 16 rotors and controllers, and 2 battery packs. Spread the power out so if one pack goes south, then only half of the rotors stop. If you are REALLY paranoid (and one doesn't become a rotor pilot without that), then you should use 4 packs, again, spreading the power distribution out amongst all of the rotors.

A good reason for 16 rotors is to spread the weight distribution out - reduce the amount of lift each rotor has to produce.

You should also consider moving the rotors above your head - in case one of the rotors flies off the motor. It also allows for you to have an unrestricted view of the ground and on the horizon.

There is (or was) a company that sells an off-the-shelf solution called hoverfly, but their website seems to be down. Check out aeroquad.com for lots of info about quads and other multi-rotor copters. rcgroups.com has a section for multi-rotor helicopters that is also very useful. 

Lastly, you will want to have some form of butt-saver - a ballistic parachute - BRS makes some very good ones.

Cheers,
Peter


----------



## otp57 (Feb 7, 2012)

LSB said:


> I had been thinking about building a lifesize quadrotor helicopter in the vain of my little blade mqx and I had a look to see if anyone had done it, and came up with this video. The team has publicly displayed this at the 2012 German Air Show and received Lindberg award for innovation. There is a couple of other images if you search this subject, but this is the only one I know that has been built.
> 
> 
> 
> ...


Not that is something to see working.


----------



## PThompson509 (Jul 9, 2009)

From what I've read, it is more important to have the CoG close to the center for most systems - if you are overpowered, it actually helps to move the mass closer to the outside.

Lots of choices for self-leveling software - DIYdrones.com, scoutuav.com rcgroups.com talk about the various packages out there. Since you have mentioned the Arduino processor, then check out aeroquad.com.

Pilot? Nope. Use a remote control, as the germans did in your video. Once you have tested it remotely, then sit in it and use the remote. MUCH safer that way.

You miss the point with using only 4 motors, instead of 16. The systems are designed to use lots of motors, and can compensate quite well if one (or more) quit. I saw some software that could compensate for up to 1/3 of the motors quitting.

Speaking as a private pilot - redundancy is a VERY good thing. 

Personally, I think you are going to have a BLAST working on this. You really should hook up with the local EAA (experimental aircraft association) to see what you need to deal with legally (on my long list of things to do).

Cheers,
Peter


----------



## LSB (Jul 25, 2012)

PThompson509 said:


> From what I've read, it is more important to have the CoG close to the center for most systems - if you are overpowered, it actually helps to move the mass closer to the outside.
> 
> Lots of choices for self-leveling software - DIYdrones.com, scoutuav.com rcgroups.com talk about the various packages out there. Since you have mentioned the Arduino processor, then check out aeroquad.com.
> 
> ...


Thankyou for the scoutuav link I hadnt been there before! I appreciate you chiming in here! 

The idea really centers around making flying more accessible due to the advantages of a multirotor setup. Risk management then becomes paramount, obviously. To mitigate a single controller failure, more than 4 rotors are necessary, there is no argument from me there.

A complete solution for mitigating propeller failure and or dislodgement is also going to be near impossible in a 4 rotor due to the area of thrust required meaning the rotor force (Due to its size/mass) will pierce even a carbon fibre cockpit, thus endangering the pilot.

These have been issues I have been considering since the start. I am reluctant to go with 16 rotors as, frankly, its been done. The e-volo team are moving toward a design that is very similar to that which you have described. (16 rotor, low slung cockput).

I do, however think than an 8 rotor setup would mitigate most of the problems that a quadrotor presents. Using 2 controllers, a single controller failure will leave 4 rotors functioning and the overload capacity of electric motors means that the craft should be able to be recovered in most circumstances.

Also, some sacrifices in prop design may be viable, such as using a composite material that will not pierce a cockpit. The field of vision issue is addressed by changing the engine support structure design. Something like this perhaps. (I hate you sketchup!)









I have built two mini quadcopters using arduinos and I am helping a friend with his 8 sided octorotor build. I had considered the Octorotor design before but the weight required because of the 8 support structure design would be prohibitive (especially on a budget). At University, a long time ago, we were involved in a study of the vector advantages of multi rotors and ever since, I have been waiting to see them fill the skies......

High energy consumption and weight augmentation, as well as software are the real hurdles here for the EV proposal. Will the attainable range make the machine viable, can we find/write/comission software reliable enough in a short time frame? 

I really want to keep the CoG as neutal as possible on all axes. I'm more set on this than I am on not using the 16 rotor option. Field of view will be fine, performance will be improved and it looks like more fun (big plus!) having the cockpit slung centrally.

I have a recrational restricted pilot's license in Australia, I live here in a small outback town and while we have the resources, people-wise there is just a draftsman and a (read: dodgy) civil engineer indulging in this craziness. If not for access to the internet and forums like these, it just would not get done.


----------



## ricklearned (Mar 3, 2012)

LSB said:


> Thankyou for the scoutuav link I hadnt been there before! I appreciate you chiming in here!
> 
> The idea really centers around making flying more accessible due to the advantages of a multirotor setup. Risk management then becomes paramount, obviously. To mitigate a single controller failure, more than 4 rotors are necessary, there is no argument from me there..........


I live near the Robinson Helicopter plant, in Torrance California, and have read about Frank Robinson's approach to helicopter manufacturing. I is all about quality control as a risk management strategy. That is why he is one of the few, if not the only manufacturer of civilian helicopters in the country. You are on the right track.


----------



## Nathan219 (May 18, 2010)

Helicopters the mechanical engineers answer to flight. My $0.02 Keep human fleshy bits out of the plane of rotation of the blades. I see spinning blades in plane with that models neck.


----------



## LSB (Jul 25, 2012)

ricklearned said:


> I live near the Robinson Helicopter plant, in Torrance California, and have read about Frank Robinson's approach to helicopter manufacturing. I is all about quality control as a risk management strategy. That is why he is one of the few, if not the only manufacturer of civilian helicopters in the country. You are on the right track.


Frank Robinson single-handedly saved the Piston engine for copters, an amazing bloke and an inspiration to all.

Here is a little updated concept drawing









I'm currently researching motor/controller choices for 8 rotor option. They will need to be >7hp continuous.


----------



## jk1981 (Nov 12, 2010)

What control system do you propose for this? Nobody in their right mind would strap themselves into something running function and safety critical software developed for toys running on a single 5$ processor plugged into a single 50$ IMU plugged into a system that will have had no EMC testing done driving cheap mass produced inverters powered by hobby grade batteries. I presume you plan to fly this without any kind of certification whatsoever 

The frame, pod and shrouds are the least of your concerns. Making them adequately stiff, light and protective is going to be an order of magnitude easier and several orders cheaper than making the rest of it, the power and control system adequately safe. Doing this right is a HUGE project.

Simply adding more of the same doesn't make it safer. I'm sorry but as you're envisaging it it's absurdly risky and you're currently focused on the wrong part of the project. The pod and frame are just a big bracket to hold the important parts together. I know you're looking for support and constructive input and I know it looks like a lot of fun but if you do it like you're proposing and it'll get you or someone else killed.

jk


----------



## LSB (Jul 25, 2012)

Nathan219 said:


> Helicopters the mechanical engineers answer to flight. My $0.02 Keep human fleshy bits out of the plane of rotation of the blades. I see spinning blades in plane with that models neck.


I understand and agree with the concerns of this aspect of the design. Even in a Octocopter setup there is a chance that catastrophic failure and dislodgement of a rotor may cause the rotor to pierce the cabin. That being said, the failure of a rotor in any helicopter will almost certainly end in casualty. The chance that the failure of a rotor in an octorotor will cause injury is far far smaller. The other possible problem is debris, which if it comes into contact with the rotor can be spat at great velocity toward the fuselage. This however cannot be mitigated by moving the fuselage below the plane of rotation as it is more likely debris will be directed south.

If we decide to sling the fuselage below or above the plane of the blades, there are sacrifices. Going above will seriously hamper stability dynamics and going below means a significant drop in response and performance, and likely increases weight.

It is the first thing most people I have shown have said when they first see it though. Perhaps using a 16 rotor setup will look less daunting with the smaller size of rotors, maybe not. I just don't think i can afford to sacrifice response in an electric aircraft when its effectiveness will depend on whether a decent range can be delivered. It's worth perhaps knocking up a model with fuselage slung below though......It may end up my only option.


----------



## Duncan (Dec 8, 2008)

Hi Guys
I expect you have already done the physics but just in case

Thrust = mass flow rate x exhaust velocity
Power = 1/2 mass flow rate x exhaust velocity squared 
(this assumes the prop is 100% efficient)

Air masses ~1.22Kg/m3

Set yourself up a spreadsheet and play with the numbers

What you find is that your Kg thrust/Kw power is dependent on exhaust speed
at 5m/s you get 40Kg/Kw
at 10m/s you get 20Kg/Kw
at 20m/s you get 10Kg/Kw
at 40m/s you get 5Kg/Kw

Lets say you can make it all up 300Kg (including pilot)
at 5m/s you need 96 m2 of fans and 7.5Kw
at 10m/s you need 24 m2 of fans and 15Kw
at 20m/s you need 6 m2 of fans and 30Kw
at 40m/s you need 3 m2 of fans and 60Kw

So what size of fans do you intend?


----------



## LSB (Jul 25, 2012)

jk1981 said:


> What control system do you propose for this? Nobody in their right mind would strap themselves into something running function and safety critical software developed for toys running on a single 5$ processor plugged into a single 50$ IMU plugged into a system that will have had no EMC testing done driving cheap mass produced inverters powered by hobby grade batteries. I presume you plan to fly this without any kind of certification whatsoever
> 
> The frame, pod and shrouds are the least of your concerns. Making them adequately stiff, light and protective is going to be an order of magnitude easier and several orders cheaper than making the rest of it, the power and control system adequately safe. Doing this right is a HUGE project.
> 
> ...


The project was originally for RC consideration only. An UAV of full-size proportions, controlled by said cheap software/processor/motor/battery etc.

Our neighbours are many miles away and we get bored, so we muck around with cars and other machines alot. Then about 4 weeks or so ago my wife crashed my car and knocked herself around a little. I've now taken 12 months off work and want to get some real projects done in between bringing my mrs food and comfort.

We have been messing with multirotor rc builds and the bigger we build them, the better! So we were talking of doing the full-size thing until just a week or so ago, my brother flew his quadcopter using fpv camera to our neighbor, who nestled a 26oz bottle of rum in the net slung underneath. He then flew it back to our house and the rum was delivered safely. It was after drinking said bottle of rum that we decided to instead build a manned multicopter.

I'm not actually going to jump in and fly this thing at 100knots and 1000 feet. I wouldnt even consider flying untethered without specifically designed software. It will fly though. When it flies the real development begins. Mucking around with chassis designs and configurations is EXACTLY what I should be doing right now. I really think that throwing a team into motor/battery/controller R&D as it pertains to helicopter dynamics is an absolutely ridiculous proposal if you havent even tested if the design can work!

I'm just a draftsman with the cheap version of a private pilot's licence, I don't care about improving electric motor designs. To me its a damn simple arrangement. Use already developed and tested systems to get the thing off the ground. Find out exactly as the vehicle behaves with variables you can change like total rotor diameter, horsepower, weight distribution, rotor arrangement, software and the list goes on and on. 

If I want to make money by selling these things I have to make it safe. So, THEN you can think about having the electrical system specifically designed for the purpose. Then you contend with the pertaining laws and permits and registration etc. Then its a registered flying vehicle and by pure luck all the investment comes to fund a business building these things. You then navigate the bermuda triangle that any inventor enters when selling a vehicle that doesnt burn oil. If you are still alive, you can spend the rest of your life in court over patent disputes and personal injury lawsuits. No Thanks. Im just going to make one for me and give back everything I have learned to anyone that wants to know.

I have no doubt that electric multicopters are a part of our future. I'd like to contribute to this through using my skills, contacts and resources to test and troubleshoot.

My original post could be interpreted as a crazy man about to mass market death machines so I don't blame you thinking that way, and thanks for the input!


----------



## LSB (Jul 25, 2012)

Duncan said:


> Hi Guys
> I expect you have already done the physics but just in case
> 
> Thrust = mass flow rate x exhaust velocity
> ...


Thanks for the input Duncan. I had used the same formula to estimate required power.

The current idea using the dimensions of the concept model is to use 8 (1m diameter) blades.

I have also allowed a 10% reduction in effective thrust for distortion (due to chassis structure)

This leaves an effective total area of 5.6m2 which falls around about 23m/s and 34kw. When then have to allow for losses through the electrical system, which at is estimated at 15%.

This bumps up power requirement to around 40kw to hover. To mitigate other forces and allow for movement along both the horizontal and vertical plane, the motor must be able to deliver significantly more.

This is where it gets funky in a multirotor setup. Because the only system mechanism is differential thrust, power required is possibly not governed by take off, as with a normal helicopter, but by the requirements of the pilot for maneuverability and top speed.

This also compounds the problem of choosing an appropriate prop diameter as the torque required to increase rotor revolution rate increases with thrust area.

Because the goals for this project include high maneuvurability I think the method of attack is to go with the smallest rotor diameter that can be afforded by power and battery life/weight constraints. This will allow for fast responses to pilot input.

40kw/8=5kw per motor to hover at 5.6m2. That means that to handle any input, the motor will be put in an overloaded state if it is rated at 5kw continuous. Perhaps we can afford a larger rotor diameter making a 5kw viable. Perhaps not.

Thanks to the spreadsheet idea, i'm starting to see that there might be different methods of attack when we increase rotor diameter. Might head to physics forum to find the formulas i need to estimate the rotor mass to rotor acceleration relationship to see what size rotor i can afford with a 40-50kw setup without losing too much agility!


----------

