If you want to try an easy conversion try finding a weedeater 21cc with the long shaft and run it on GAS/GLOW, all that is involved is stripping the engine out of the weedeater, cut away the extra metal with a hacksaw, do a little grinding and if you do find the long shaft all you have to do it extend the threads on the end of the crankshaft with a die, for a prop hub all you need is a pc of 1" or 1-1/4" aluminum rod with a 5/16" hole drilled in the middle ( use a lathe ). To run gas/glow you just remove the flywheel, coil and sparkplug and use one of these http://www.horizonhobby.com/Products...rodID=ZEN23445 with an OS F fourstroke glowplug, richen the needles a bit and for fuel you mix 1 part 10%nitro/10%oil glow fuel with 2 parts premium gasoline ( check the ENGINE CONVERSION forum for more info ). Here's some pics of my 21cc that runs on gas/glow, it will turn an APC 17x6 @ 7200 rpm.

What i like about gas/glow is no more messy planes after a flight, no chance of RX interferance as there is no ignition ( operates just like a normal glow engine), no extra onboard battery and run time is only a little less than gas/oil mix, on most engines you get more power than gas/oil, easy to start, very low idle and light weight ( my 21cc with steel muffler was 32 oz ).