Rotary Radial Engines

That is not a typo, in the early days of aviation planes often

used rotary engines. In this design the entire engine rotated

and was attached to the propeller while the crankshaft was

fixed to the plane (The exact opposite of the way things are

generally configured). This may seem like a strange way to

go about the business of powering an airplane, but it worked

surprisingly well. The momentum of the heavy rotating engine

and propeller had several benefits. The mass of the rotary

allowed the engine and prop to continue rotating even

if the engine was not firing.In these times carburettors

were very primitive and could not maintain the proper air

and gas mixture as the throttle was open and closed. The

rotary design allowed the pilot to set the proper mixture at

wide open throttle and use the ignition to vary power delivery.

Simply put, when the pilot wanted to land, he would simply

cut off fuel and let the propeller and engine windmill during

the descent until he was about to land and needed power once

more. At this point the pilot would open the fuel valve and the

engine would re-light at full throttle. During the final approach

and landing, the pilot would briefly cut the ignition to vary

amount of power delivered by the engine. It's hard to describe

but the sound is unmistakable, check out the video, you will

see what I am talking about.

Also here is a video of the full sized version in a Sopwith Camel