K engine driving an ultralight

[FranK75]

The K engines are powerful, high output for their weight, reliable. I am considering using a K75 engine to power an ultralight airplane. May have to shave off weight where ever possible.

[Chaos]

good ones are pretty cheap on the market too.  Not sure how you'd shave weight aside from the transmission & clutch.  Maybe lighten the flywheel.

[FranK75]

I would grind off as much aluminum as possible from all over the engine

[Chaos]

Seen R100 and 1100 engines on ultralites and small planes.  Makes sense, no radiator to worry about

[Mongrel]

Yeah, maybe something air-cooled would have a better power-to-weight ratio? Not sure, but worth looking into!

[FranK75]

Great points on the air cooled. Thanks - makes more sense.

Frank

[wmax351]

Air-oil cooled R11's or R12's are probably a better bet. The oil cooler can be thermostatically controlled, and potentially controlled with flaps. Also, carbureted and can be set up with dual plugs and (potentially) magnetos. Don't want engine failure from electrical failure. That way you can duplicate critical parts.

Counter Balancer adds some weight too.

BMW bike engines are good for this, they have a high duty rating, and separate engine/transmission.

You will need to consider the thrust loading on the output shaft. If you are doing a reduction drive (which I would assume you are) that will take care of it.

[F14CRAZY]

Someone's done it before

http://www.homebuiltairplanes.com/forums/general-auto-conversion-discussion/4438-bmw-motorcycle-engine-plane-3.html

[Laitch]

It'd be more adventuresome to use a Ural engine; however, you'd probably be making shorter flights. :hehehe

[FranK75]

No problem. I would bring lots of tools and spare parts.

[Chaos]

It'd be more adventuresome to use a Ural engine; however, you'd probably be making shorter flights. :hehehe

As a rabid Uraligist I resent that remark though I cannot argue with it  :giggles

[F14CRAZY]

How about a Chang Jiang engine?