Can I convert an outboard boat engine to power an ultralight airplane?

Question

I'm just kinda curious, is it possible to convert a small-horsepower (25-30) outboard marine engine so that it'll power an ultralight airplane, weighing no more than 250 lbs empty? I know that other types of engines are converted, but I've never heard of someone converting an outboard engine, and I don't know why because it seems like a rather good idea...horizontal shaft, compact size, all-weather operation, and lots are even electric start and come with the throttle control lever, which would work well if used for an airplane. So why don't I see people doing this all the time? Is there some impassable design flaw or other reason not to do this?

Just wondering :)

Answer 1

you can do it but you wont see me on that plane i garentee that

Answer 2

No, because outboard motors are water-cooled, so unless you are flying in water the  engine will over-heat and seize.

Try using a lawn-mower engine, or one from a chain saw.

Regards,

Dan

Answer 3

cooling and drive shaft direction are problems. weight is more on outboard.

Answer 4

I guess you could do that, but there are a lot of things to think about. I don't think it would be practicle to do that. Marine engines are water cooled and that would be a big problem.

Answer 5

problem is that none of the aircooled outboards meet your power requirement, and none of the watercooled outboards have radiators - they draw water from the lake or ocean.  

Two stroke motor has favorable power-to-weight characteristics - how bout a motorcycle engine?

Answer 6

Outboards are actually vertical shaft.  The gearcase on the bottom transfers the power to horizontal.  Not only are they water cooled, but the water inlets and outlets are cast features that must match up with the water passages on the exhaust housings, so you'd have to make an adapter plate with hose connections to provide cooling water, and you'd have to have a radiator and water pump somewhere on the craft.  Good question though, it's good to be curious.  Snowmobile type engines, like the Rotax, are the norm for ultralights.  Lighter, higher revving, simpler, etc.

Answer 7

No they are water cooled and you need an air cooled engine for the plane.

Answer 8

The only flaw is that marine engines use water to cool itself down....

Answer 9

Yes there have been outboard engines converted for experimental airplanes.  I've seen several 4 cylinder engines done.  I don't know what FAA reg. require, but keep in mind that these are water cooled engines, not air cooled.