# Electric Aircraft for STOL use



## Caps18 (Jun 8, 2008)

I've seen a few electric plane builds. 

Here is a ultra-light one:
http://www.youtube.com/watch?v=YINO0aoSAGg

And here is a cool 'normal' type of personal plane:
http://www.youtube.com/watch?v=WqEKSAmiv68

I think you will have to wait for the next generation of batteries though. And the design for the wings might need to change for an electric motor to allow better lift or faster speeds using less power.


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## Tesseract (Sep 27, 2008)

nickflatoff said:


> ...So, here is the whimsical idea: convert an aircraft to electric power and still have room left over for transporting stuff.
> ...
> First of all, I'm curious if there is a good way to compare the power of electric engines to its gas counterpart. The ch801 usually uses a Lycoming O-360, which produces [email protected]
> 
> The engine and fuel take up about 500 pounds, so the total weight of the electric power train would--ideally--be right around that weight.


Aircraft engines are typically run at 80% of their maximum power when cruising, so to replace an O-180 you'd need 140-150hp *continuous* (or 104-112kW), but, yes, you will need the full 180hp during takeoff or when climbing. This is a pretty high level of continuous power for on-road vehicle, but something like the Remy HVH250 (interior permanent magnet AC) motor would be an excellent choice here, though it and the inverter required to drive it will set you back some $15k, IIRC.

The real obstacle to electric airplanes is the size and weight of the battery pack required to deliver ~100kW for a useful length of time. Just to fly for 15 minutes will require some 30-35kWh, which is enough capacity to give most EVs a 100 mile range, but which might get you 20-40 miles of range in a small plane!

So, yeah... we ain't quite there yet with battery technology. Check back in 20 years or so.



nickflatoff said:


> It seems like the general consensus is that home built controllers are the economic choice. Is there a good introduction write-up on that somewhere out there?


You want to fly around 3rd world countries in a homebuilt plane with a homebuilt controller? Is your ulterior motive to meet the object of your worship and devotion sooner rather than later? 



nickflatoff said:


> Slightly unrelated, but on takeoff/full throttle, the plane is using 180hp, and that is a standard, so for the same performance on takeoff I would need 180hp out of an electric motor? Or is there some cool math regarding torque that I'm missing?


Sorry, no cheating of physics allowed... You will need 180hp to takeoff and climb at the manufacturer's rated specs. Anything less than that will result in reduced performance and below some critical power level you will stall as soon as the plane rises above its own ground effect, with predictably disastrous consequences.


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## MN Driver (Sep 29, 2009)

You aren't going to be able to pull 180HP as long as you would need to climb to altitude in an aircraft with a WarP engine. The WarP motor's one hour rating is less than 40 horsepower.

Almost everyone using electric motors in aviation has gone the brushless DC route. I haven't come across any Series DC or AC motors. One of the primary reasons is BLDC allows for tons less copper by replacing about half of the copper with lighter permanent magnet motors. They are also amongst the highest power to weight ratio and most efficient motors out there.

Regarding torque, with cars people talk about electric motors having tons of torque, they do, which makes them feel great off the line as they are near or exceeding the limits of traction. With an aircraft it's different, since your prop is moving air, that torque at low RPM doesn't matter because to move air you've got to get that prop spinning at speed and under full power you'll be cranking that prop at a higher speed than cruising. For boats and planes, it's the high horsepower requirement that matters and it's a challenge getting that same power handling in an electric motor and trying to cool the motor so it can withstand it. Also keep in mind you'll need a whole bunch of battery to fly a plane.

Edit: Looks like Tesseract beat me to the punch and explained it better, but I'll leave this here. As an added comment, the guy who converted the Lazair was on the right track in using a small low load double prop plane to power electrically. In an area where you are encountering enemies, you might be the mosquito that they want to squash for fun on the side if you fly around in an ultralight. I'm not sure what you are trying to accomplish is very possible. I'd probably start with a Cessna 150/152 or something else that can actually get gas mileage similar to a more gas guzzly car to start with and then realize your range will still be quite limited.


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## nickflatoff (Sep 1, 2012)

Tesseract said:


> So, yeah... we ain't quite there yet with battery technology. Check back in 20 years or so.


Ah, I figured... I was running the numbers on 4 WarP11HV's, and just running them at an average speed took up nearly all the useful load for just an hour and a half, not including drag. Then I thought, might as well ask the electric car guys anyway!



Tesseract said:


> You want to fly around 3rd world countries in a homebuilt plane with a homebuilt controller? Is your ulterior motive to meet the object of your worship and devotion sooner rather than later?


 You might have something there. No, "homebuilt" means "fixable in difficult situations." They teach us how to fabricate tools and parts. The FAA doesn't rule in Kalimantan 

Thanks for the responses. I'll keep dreaming...


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## Salty9 (Jul 13, 2009)

You might check into ethanol or biodiesel fueled engines. Either fuel could be locally produced with a minimum of equipment.


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## AME (Mar 10, 2013)

Salty9 said:


> You might check into ethanol or biodiesel fueled engines. Either fuel could be locally produced with a minimum of equipment.


Either of these would be preferrable to going the all-electric route in a STOL aircraft like an 801 given the current state of development and risk to life and limb. (Actually an electric moto-glider would be a safer bet given the glide ratio, but you'd give up STOL characteristics). 

But even with ethanol and biodiesel there are safety factors to be considered when used with aircraft that don't apply to ground vehicles. With ethanol there's the increased risk of water absorbsion in the fuel as well as an increased likelihood of vapor lock. With biodiesel there's the problem with solidification of the fuel at lower ambient temps. Even on a warm day the air temps aloft decrease anywhere from 1.5 to 3 degrees with every 1000-ft increase in altitude. And engine failures caused by fuel supply interruptions can get you seriously killed every bit as fast as those caused by catastrophic siezure/breakage of internal engine components.


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## deckofficer (Apr 3, 2012)

I also like the idea of an electric airplane, no TBO, no $15K overhaul, clean and quiet. Chip Yates has run over 200 mph in a modified Long Ez (Rutan design) on lithium ion batteries. However this run toasted some cells and he had to dead stick back to the airport.

There are a few offerings but none suitable to your mission. A STOL aircraft is typically not very efficient, a good candidate for bush work, but high fuel burn for a slow cruise speed.

A new plane on the market, a French designed canard pusher, would be a good candidate for electric because of its air frame efficiency of being able to cruise at 200 kt on less than 100 hp and gets over 35 mpg at this speed and at 100 kt 55 mpg. Of course this is not a STOL bush plane.

http://www.sbap.be/events/2012/031elipse2012/031elipse2012.htm

http://www.lhaviation.com/index.php?option=com_content&view=article&id=46&Itemid=37&lang=en


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## etlaare (Aug 25, 2009)

http://www.youtube.com/watch?v=oD8TfjDMYT0


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