Electric motor?

[mspohr]

I was wondering if anyone had put an electric motor in a Kitfox?
I was thinking that it could work well in a Kitfox since it would be lighter, require much less maintenance, be less susceptible to mechanical failure and could offer enough range for average use.
I am not a pilot but have been intrigued by the Kitfox as a simple, fun aircraft and this might motivate me to try to build one. In reading this forum, it seems that the major problems with flying the Kitfox are due to the engine. Lots of problems there. Electric motors are very simple and very reliable. Same for the batteries and control systems.
An 80 to 100 HP electric motor would weigh 100 to 150 pounds and batteries are about 50 pounds per 5 kWh storage it seems to me replacing the motor, cooling system fuel tanks and fuel weight with an electric system could result in a lighter aircraft. Electric motors, of course, don't suffer loss of efficiency with altitude. They also have nearly constant torque over their entire speed range.
So, is this idea crazy?

[PapuaPilot]

No, it's not a crazy idea. You are correct in wanting to find a light airframe like the Kitfox to convert to electric. Siemens already has a 120HP electric motor that only weighs 57 pounds, which is being tested on the Sun Flyer 2 all electric aircraft. The biggest challenge for any electric aircraft will be batteries and getting enough energy density to be able to fly for an acceptable amount of time.

[rv9ralph]

It looks good on paper. However... the Pipestrel Electric program for flight training in Fresno, CA is a place to look for practicality. The program manager for this endeavor spoke to an EAA meeting I attended about the program. The details are the issue. 45 to 90 minute flight times with reserves, then need to recharge (must have a charging station at the destination airport to charge for return flight.) The battery unit replacement/spare is $70K. Even though you don't need fuel, as fuel burns off the aircraft gets lighter and performs better... batteries stay the same weight regardless of charge level.

Electric flight is possible eventually, but I don't think it's time is right yet. At least for practical use.

Ralph

[mspohr]

Interesting to hear about the Fresno experience with the Pipistrel.
I looked at the Pipistrel Alpha Electro. It's also a light two seater frame and focused on flight training since the cost to operate is just a couple of dollars an hour for electricity.
They use a 50 kW electric motor (about 65 hp) with 106 kg of Tesla style (18650) batteries which should give them about 25 kWh of power. They state an hour of flight time with 20 min reserve. (They also say they can regenerate up to 13% of the power when descending)
You can buy Tesla battery packs for about $1300/5.3 kWh so about $6500 for 26 kWh batteries. Electric motor would be $3000 to $5000 plus controller.

As far as "range" goes, just like with electric cars, it depends on your use. I believe that most flying in this type of airplane is short distance, short duration. I saw a survey that that found most pilots for these light sport aircraft fly less than an hour at a time. Cross country travel (to Oshkosh!) would require frequent stops for charging. Pipistrel says an hour of charging for an hour of flying... so this would be slow.

[Dorsal]

Interesting to hear about the Fresno experience with the Pipistrel.
I looked at the Pipistrel Alpha Electro. It's also a light two seater frame and focused on flight training since the cost to operate is just a couple of dollars an hour for electricity.
They use a 50 kW electric motor (about 65 hp) with 106 kg of Tesla style (18650) batteries which should give them about 25 kWh of power. They state an hour of flight time with 20 min reserve. (They also say they can regenerate up to 13% of the power when descending)
You can buy Tesla battery packs for about $1300/5.3 kWh so about $6500 for 26 kWh batteries. Electric motor would be $3000 to $5000 plus controller.

As far as "range" goes, just like with electric cars, it depends on your use. I believe that most flying in this type of airplane is short distance, short duration. I saw a survey that that found most pilots for these light sport aircraft fly less than an hour at a time. Cross country travel (to Oshkosh!) would require frequent stops for charging. Pipistrel says an hour of charging for an hour of flying... so this would be slow.

I think it is an issue of range. It is fairly typical to cruise at 75% power (very different than car), not sure how you get more than about 30-45 min flight time from the example above. While it maybe true that many flights are less than an hour I can't imagine owning a plane with that fundamental limitation. As others have stated it is getting closer but not there yet in my opinion. One place this does work is small booster motors for motogliders.

[mspohr]

I was just wondering... what is the range of the Kitfox with a Rotax or similar engine?
Fuel consumption gal or pounds per hour?

[109JB]

I was just wondering... what is the range of the Kitfox with a Rotax or similar engine?
Fuel consumption gal or pounds per hour?

So I have a Kitfox IV powered by a Rotax 582. Winter hit too soon after I bought it but near as I can figure it should cruise about 90 mph using about 4 gallons per hour. I might be off a little because I haven't had chance to nail down my cruise numbers yet. My particular airplane has two 13 gallon wing tanks which would theoretically give a 6.5 hour endurance at 4 gph and a 585 mile range. Not all kitfoxes are outfitted with tanks this large though.

[109JB]

I think it is an issue of range. It is fairly typical to cruise at 75% power (very different than car), not sure how you get more than about 30-45 min flight time from the example above. While it maybe true that many flights are less than an hour I can't imagine owning a plane with that fundamental limitation. As others have stated it is getting closer but not there yet in my opinion. One place this does work is small booster motors for motogliders.

I agree with most of this post but I do see a bit more potential.

Since most flights leisure flights are an hour or less, a guy that only wants to do that type of flying could benefit from one. I used to be in a flying club that had 2 airplanes and the less than an hour for a typical flight is absolutely accurate from my experience. I was also one of the flight instructors for the club and the longest flights of the month were generally the flight instruction flights. If our flying club had an electric LSA and a C-172 instead of 2 C-172's, I would guarantee that the electric LSA would have gotten as much use as it could handle. The only potential problem I see is recharge time or I see some systems looking a battery swapping.

A pure flight training type environment might be ideal at this point in time. This use would get benefit from a lot of regenerative capability (TOL's)

From a personally owned airplane perspective, I'd do it as a second airplane if I had that much disposable income to play with. I think it would be an interesting and fun project and could fill the evening flight role with another airplane serving the travel duties.. Due to the range limitations it wouldn't be practical as an only airplane because I do like to make short trips from time to time.

[efwd]

Don't forget the reserve.

[Shawshaw]

Don't forget the reserve.

What about the idea of a hybrid? Light weight ~80hp gasoline engine generator, small battery bank as a buffer, used Tesla motor to drive the prop?