rotax 80hp vs 100hp auto conversion

[mscotter]

huh, interesting, but what would it weight? I just did a search and one site said ready to run engine (i.e. with exhaust, airbox, etc) would be 220lbs. Then there's the connection to prop to consider. Would you need a reduction drive? Or could you use the bike's gearbox? Still you'd need some kind of additional custom machined parts to attach prop, so the weight is climing fast...

[TahoeTim]

not the hyabusa

I screwed up. I meant Yamaha, not Suzuki.

It's the Yamaha genesis 3 and 4 cylinder with the C box.

[dynomike]

I own a hayabusa .incredible engine ,but its making its 220 horse at over eleven thousand rpm,wonder what its making at only 5000 ,maybe one hundred .

[av8rps]

Tim; Yes I have heard some good things too about Gyro guys using the Yamaha engine with the Rotax gearbox. I heard the Yamaha engine is about 130 hp stock on the sled, but I just haven't seen one on an airplane yet. I think that would be a cool set up, if they can hold up.

Dynomike and others; Yes, I agree that the weight could add up fast on the Hayabusa. But typically when you use a bike engine on an airplane you remove the transmission from the bike engine because you don't need it. But at 11,000 rpm the gearbox gearing could be a challenge I'm sure. So maybe you'd have to keep a couple of those gears

I remember seeing a WWI replica at OSH a bunch of years ago that used a Yamaha Virago 1100 CC motorcyle engine. It looked cool under the cowl, and sounded even better. The owner/builder made a large belt drive as I recall, but kept the bike gearbox as he said it really worked well to be able to "Shift gears". Because of the gearing ability he had it turning a really big prop - something like 84 inches with really wide and fat blades. (Hmmm...so how would the FAA handle an aircraft engine that had the ability to "shift gears"? Could that be a way to gain performance on an LSA, while getting around not being able to have an adjustable pitch prop on an LSA? Just say'in....)

I know if I had the time and desire to tinker with an experimental aircraft engine conversion, the HP coming out of that Hayabusa would be very tempting and would motivate me to find a way to make it work. And while it is very likely it would be heavier than the 912 Rotax, I believe the significant gain in HP just might make that conversion worthwhile.

And heck, if guys have successfully converted 80 - 90 hp BMW and Honda Goldwing engines to aircraft use (at least a couple have), I'm pretty sure the Hayabusa could be too. If there's a will, there's a way...

[Av8r3400]

But at 11,000 rpm the gearbox gearing could be a challenge I'm sure.

The hot section of a Pratt & Whitney PT6 turns 30,000+ rpm and the prop turns 2000 or less (both depending on the model). These only have a double planetary reduction. Anything is possible, just insert money...

[PapuaPilot]

The smaller PT6 engines burn about 50 gallons per hour. They weigh around 350 pounds dry and swing props that are nearly 100" in diameter. That's not very practical on any plane under 6 seats.

[Esser]

I think the small ones like on the meridian burn about 30 gallons an hour.

[Av8r3400]

I wasn't suggesting he installation of a PT-6, yes, that would be crazy.

I was citing an example of a common, reliable PSRU that takes very high rpm and lowers it by a factor of 15 or more. The engineering is possible but it will take a great deal of effort to make it a reality.

[mscotter]

Most all Jap bikes have the gearbox included as an integral part of the case. They are in the same oil bath as the engine and highly integrated. They are not easily separable from the engine like perhaps on a HD. Removal would involve some extensive creative machining.

[TahoeTim]

That's exactly why these guys are using snowmobile (sled) and jet ski engines. No gearbox to chop off the engine. Apparently snowmobiles get wrecked quite often, providing a good supply of slightly used engines.