A while ago I converted a Ryobi 31cc to airplane use. I flew it a few times on this scratch built coroplast plane I made. It worked fine. I just used the stock Walbro and gutted the muffler to get a modest 7000 RPM with an APC 16x8 prop. This turned out to be just the right amount of power. Not overpowered, but not underpowered. Full throttle wasn't needed to stay airborn.

The engine and plane has been collecting dust for about a year now, so I decided to mess with it again. However this time I wanted to run it on alcohol. I though maybe I could get a few more RPM's. So made a crude little adaptor out of some aluminum and JB welded an OS 4B carb (came off an OS.40 but has about the same bore (maybe awee bit smaller)as the stock Walbro). For fuel I just used some denatured alcohol and some Klotz Super Techniplate at 5%.

IMO it runs better now. I mean it actually has a midrange instead of just high and low like it did with the Walbro. Plus the idle is more reliable. Just all around smoother.

Yes fuel consumption is greater, but it doesn't gulp fuel.

RPM is the same as with gas.

I think I could have squeezed a bit more RPM out of it over the gas if I used my Super Tigre .40 carb. It is quite a bit larger than both the stock Walbro and the OS carb.

[youtube]http://www.youtube.com/watch?v=yXqBYO-ApsI[/youtube]</p>

A WT-499 Walbro is designed to run alcohol. Should give you more power, plus the advantage of a pumped, regulated carb instead of a glow carburetor.

AV8TOR

Walbro actually makes an alcohol carb? Neat. I didn't know that.

Do you think some nitro, say 5%, would also help in the power department?</p>

A little nitro probably couldn't hurt. Be careful how much power you make with the Ryobi. The stock stamped steel rod is only good to about 7500 rpms.

This thread might interest you: http://www.rcuniverse.com/forum/m_80..._1/key_/tm.htm

AV8TOR

Thanks. I read that thread a while back before becoming a member of RCU. I even came up with my own gas/glow brew for regular two stroke glow engines. It is 1/2 gasoline with 25% oil and 1/2 0% nitro glow fuel with 25% oil (I made the glow fuel part myself). It worked great in a Fox .40 R/C with an OS A3 plug. Never had a dead stick.

If 7500 is the max for the Ryobi then, my 7000 isn't as low as I thought.

I'll try some nitro tomorrow and report back.

Do you think a Ryobi could fly (not 3D) something like this:

[youtube]http://www.youtube.com/watch?v=rJgi52PdyPA[/youtube]

I mean I have made dozens of regular size glow PBF's and I would love try a giant scale version.

you should have plenty of power, those pbf's weigh nothing....engine weights more than everything else