Cool, thanks for that. The top motor is a radial, meaning that the cylinders radiate out from the crankcase. Imagine a v-twin, but with cylinder all around in a circle. The motor is fixed and the crankshaft rotates inside the crankcase, just as it does with all 'regular' motors. The propeller is attached to the end of the crankshaft, either directly or through gears.
The bottom motor is a rotary, meaning that it is set up in reverse. The crankshaft is fixed, immobile, and the whole engine rotates around it. The propeller is bolted directly to the crankcase. Lubrication is constant-loss using Castor oil. Hence, if you are up on your Biggles stories, the fact that you could always tell the pilot of a rotary engined plane by the burnt Castor oil residue all over his flying jacket. In the same way that gyroscopic precession dictates the reality of how we steer a motorcycle at speed (because the front wheel/tyre acts like a big gyroscope) the rotary motor was actively involved with the manoeuvrability of the aircraft....try to turn 'against' the gyroscopic effect of the mass of the spinning motor and the aircraft turns sluggishly; turn 'with' the gyroscopic effect of the motor and the aircraft whips around very quickly.
Combat pilots in the more powerful rotary-equipped fighters of WW1 (such as the Sopwith Camel) used this effect to great advantage in a dogfight.
Here's a clip of a rotary being started:
Cool the way the propeller looks as it spins.
