wish to power my one man ultralght aircraft

[trimjim007]

I have a Lazair ultralight aircraft. It is powered by two 4.5 hp chain saw motors currently. One on each wing. This ultralight is well suited for an electric conversion because it is very light and has a high glide ratio. It is essentially a glider with two small engines to get it in the air. Once in the air, the engines can be shut off to ride the thermals.

I belong to a forum of Lazair owners and enthusiasts. There has been a lot of talk lately about converting to electric power. With all of the advances driven by larger and larger RC aircraft and the automobile markets, this dream is becoming more feasible every day. One of the members on the forum recently flew his Lazair powered by two light weight electric motors. But he burned up the control circuitry and is trying to figure out what went wrong.

I know very little about electric motors and their capabilities. I joined this forum to learn more. I am hoping those of you with real knowledge and experience can help. Any suggestions will be greatly appreciated.

This RC airplane weighs 801 lbs which is much heavier than My lazair. http://www.youtube.com/watch?v=jFSOMzTromM

My Lazair weighs 165 lbs full of fuel. So I am sure it is possible.

[abernethy1]

I am not saying it is impossible but I think this plane weighs only 80 pounds.

[Jeffery]

I think it was Patrick MacKenzie who was involved with the development of an electric ultralight here on the board, it's been done.

Ah, Here ya go (http://www.rcgroups.com/forums/showpost.php?p=6725453&postcount=49).

[trimjim007]

Thanks Jeffery. OOps! you are right abernethy1, it is only 80 lbs. That is just about half of what my ultralight weighs. My wingspan is almost 40 feet! but it is very light. Made of very thin aluminum and Styrofoam. I will add a picture once I figure out how.

This beautiful Boeing B-50 weighs 462.9 lbs
http://www.4-max.co.uk/pppo-6367.htm

I am sure I saw an electric powered model that was 801 lbs. What fun!

Thanks guys. This is the motor that was used on the British built electric Lazair like mine that recently flew:

http://www.icare-rc.com/plettenberg_predator.htm

They sell for $1000 each. he used two. They already have a bigger motor available; they are a couple hundred bucks more each. A motor speed controller will run probably close to another $400 each. Then you need batteries and battery protection modules. That's where it gets really expensive.

His controller burned up? he is looking into what went wrong.

Thanks again.

[Airboatflyingshp]

There are full size homebuilt size aerobatic plane out there powered by single large out runner, geared or not?? but gearing helps you swing a lot larger prop so if speed isnt an out and out requisite remember it as an option.... toothed belts are quiet,cheap and light also they dont alter your direction of rotation. there is also in the electric motor thread several people working with turning alternators into lage scale motors... they might be onto something for your size/power range on a budget. http://www.rcgroups.com/forums/showthread.php?t=905411&highlight=motors+from+car+alternators ;)

Lots out there just keep searching , lots here just need to find the right search words.
http://dvice.com/archives/2007/07/electric_airplane_prototype_sh.php

For you, battery technology might be your problem.or rather the expence.

[Magne]

Trimjim,
Are you looking to improve the performance on your current set-up, or are you just interested in making it electric?
The reason I ask is that this thread seems to be focusing on "what is the most powerful electric set-up available" kind of thing, but looking at your initial post, you say that your current set up is with two 4,5 hp chainsaw engines. That is typical 50cc model engine size, which is a very common size for electric model conversions. (4,5 hp=3300W)
Reliability issues apart, you can get that kind of motors for $150 and regulators for about the same or less. Batteries are also readily available, price depending on required capacity/motor time. (On the other hand, if I were piloting this plane, I would go a little bit more up-marked on the motors and regulators, such as Plettenberg and Hacker. Plettenberg Terminator 30-8 is rated by the factory to 5-6 kW, on 10-12s lipo batteries. The Predator motors are more powerful, up to 15 kW.

(Electric motors also give you the option of using folding propellers, which is an advantage when you are soaring.)

Magne

[hrvojekl]

Spruce Goose from the movie "Aviator" is electric model. Wing span is 26 ft and weight is 375 lb.

http://www.aerotelemetry.com

Hrvoje

[Coastwatcher]

Thanks Jeffery. OOps! you are right abernethy1, it is only 80 lbs. That is just about half of what my ultralight weighs. My wingspan is almost 40 feet! but it is very light. Made of very thin aluminum and Styrofoam. I will add a picture once I figure out how.

This beautiful Boeing B-50 weighs 462.9 lbs
http://www.4-max.co.uk/pppo-6367.htm

I am sure I saw an electric powered model that was 801 lbs. What fun!

Thanks guys. This is the motor that was used on the British built electric Lazair like mine that recently flew:

http://www.icare-rc.com/plettenberg_predator.htm

They sell for $1000 each. he used two. They already have a bigger motor available; they are a couple hundred bucks more each. A motor speed controller will run probably close to another $400 each. Then you need batteries and battery protection modules. That's where it gets really expensive.

His controller burned up? he is looking into what went wrong.

Thanks again.



Trim ............If your chainsaw engines are only 50 cc , then you could get a a pair of the BIG AXI with the LOWEST KV rating and some 30 in props , the one withthe big bearing in front makes since to me. And a pair of JEti 200 amp controls. I a HUGE BOX of HOBBY CITY 30 C LIpos 15K worth perside should sail you around for a while . :)

[dirtybird]

An electric motor makes a lot of sense in an application like this. An electric motor is so much more reliable than an IC engine. And it develops its maximum torque at zero RPM. This means you can use a much bigger and more efficient propeller. And you can turn the motor on and off at will.
The main problem is the batteries. I would take a hard look at A123 cells. There is a guy on ebay selling large number of cells at a price of about $7 a cell. They are used cells but the 20 I have seem to be good - all of them.
I sure would not want to be in an airplane with a bunch of explosive lipoly's.

[Tonystott]

SNIP I sure would not want to be in an airplane with a bunch of explosive lipoly's.
Surely you are joking? Given the massive acceptance of LiPos in the R/C market, if your view was accurate, we would be hearing about lots of disasters....

I have NEVER heard of a LiPo "exploding" during a flight. I have heard of them burning during charging (almost always due to errors in set-up or equipment) and extremely rarely burning while in storage for no clearly found reason, but your caution is in my IMO totally unjustified.

[Magne]

I second that.
Petrol fires on the other hand.......

Magne

[Z06kal]

How much weight can you safely allocate for the entire power system + fuel?