Radials? Pah! You need a rotary – and I don't mean a Wankel engine...
To quote:
"
Balance. Note that the crankcase and cylinders revolve in one circle, while the pistons revolve in another, offset circle. Relative to the engine mounting point, there are no reciprocating parts. This means there's no need for a heavy counterbalance.
Air Cooling. Keeping an engine cool was an ongoing challenge for early engine designers. Many resorted to heavy water cooling systems. Air cooling was quite adequate on rotary engines, since the cylinders are always in motion.
No flywheel. The crankcase and cylinders provided more than adequate momentum to smooth out the power pulses, eliminating the need for a heavy flywheel.
All these factors gave rotary engines the best power-to-weight ratio of any configuration at the time, making them ideal for use in fighter planes.
Of course, there were disadvantages as well: Gyroscopic effect. A heavy spinning object resists efforts to disturb its orientation (A toy gyroscope demonstrates the effect nicely). This made the aircraft difficult to maneuver.
Total Loss Oil system. Centrifugal force throws lubricating oil out after its first trip through the engine. It was usually castor oil that could be readily combined with the fuel. (The romantic-looking scarf the pilot wore was actually a towel used to wipe the slimy stuff off his goggles!)
The aircraft's range was thus limited by the amount of oil it could carry as well as fuel. Most conventional engines continuously re-circulate a relatively small supply of oil."
Photos of a working SCALE MODEL rotary engine!
Click here for film of engine running!!!!!
http://modelrotaryflyer.tripod.com/lerhonevideo.wmv