which plane will perform the best with an 18 cc weedeater featherlite: stinger 60, GP super skybolt, or ultra stick 60? how bout around a 30cc engine, something like the ultra stick 120?

The little 18cc weedeater engines just don't put out enough power for their weight. One might work ok on a floater plane like a small cub that flies on the wing instead of raw power. The choices you outlined are aerobatic planes and you would be very unhappy with the performance. The larger 23cc and up engines are a minimum for what you seem to be looking for in a project.

Hope this helps,
AV8TOR

ok i guess ill make an airboat or something and have some fun. would the 33cc ryobi work ok on an ultra stick 120 lite?

That would probably work fine. I am just about to start a project Ultra Lite Stick 120 with a Homelite 25cc. I have been told that this flies very well. Just about any decent engine in the 23 to 30 cc range will fly the airplanes you are looking at well, but the lighter the engine the better. The Kioritz/Echo engines work great, but they are pricey unless you luck out and find a good used one. Other than that, the Homelites and the Ryobi engines are very popular and work well.

Good luck,
AV8TOR

What about converting the 18cc to glow? That will lighten it up a lot. Anyone tried this?

Yes, that can and has been done, and works fine, but the power is still not that great. Definitely not enough for a good aerobatic plane. The little 18cc weedeater motors have very small ports, low compression, and are cheaply built. They are designed to run in a $50.00 weedeater that is mass produced and you can hold the throttle wide open all day and it won't hurt itself. Better like you said, put it in an airboat or a little car than an airplane that needs a lot of power all the time. In the hot rodding world, we always say "The only substitute for cubic inches, is more cubic inches." If you want a good aerobatic plane, you are going to have to go to a larger gasser conversion engine.

Good luck,
AV8TOR

Or "The only substitute for cubic inches, is cubic money".

Steve

There is no replacement....for displacement.......shakspear!!!!!