The RCV engines are unique in that all valving is done by the rotating cylinder (sleeve), driven at one-half crankshaft speed by bevel gears as correctly stated.
There are three ports in the block (case) and one in the sleeve. The sleeve rotates such that intake port is exposed on the downstroke, drawing in fuel and air.
Continued rotation closes the intake port and the piston starts upward on the compression stroke. At some point near TDC, the cylinder port aligns with the glow plug port in the block, exposing the compressed fuel/air mix to the plug, causing ignition. Rotation continues and the piston travels downward on the power stroke with all ports closed. Somewhere around BDC, the sleeve opens the exhaust port in the block and upward movement of the piston scavenges the exhaust charge.
There are the four strokes of the cycle.
Aside from that, the version that Willis is using operates as a conventional four-stroke engine, taking power directly off the crankshaft.
Now for the interesting one, the AXIAL version. In this configuration, the only power taken from the crankshaft is to rotate the sleeve.
The power to drive the prop (output) is taken from the top of the rotating sleeve. At ONE-HALF crankshaft speed.
At the top of the engine, there is a protruding drive feature from the top of the sleeve, similar to that on the front of a conventional two or four stroke engine - a thrust washer and a threaded shaft.
The prop is actually attached to the rotating sleeve.
Since staring an RCV engine can be difficult, there is a female hex drive on one end of the crankshaft, protruding through the case.
You fit the supplied male hex driver to your electric starter and just plug it into the female drive.
Since the output torque is twice that of the crankshaft and half the speed, you can swing a huge high-pitch prop.
Bob Z.