How does a Gnome rotary piston engine work? I would like to see how it works in detail, possibly with text explanation.
Link from @Gerry 's comment: http://www.animatedengines.com/gnome.html
Short version: take a radial and attach the output shaft to the aircraft firewall/structure. Feed the intake through the shaft, let the exhaust go where it goes. Fasten the propeller to the crankcase.
These engines were usually lubricated by mixing oil in the fuel, and passing the intake charge through the crankcase (similar to a modern 2-stroke engine, though without the pressurized crankcase). Spark was produced by a fixed magneto and distributed to the plugs by a gap contact similar to that in an old style auto distributor.
Many of these engines had no effective throttle, or could only throttle a little (35%, maybe even 50% minimum power). If you see an air show with an original or repro aircraft using the correct engine, you'll hear them blipping the ignition off and back on during landing approach, as that's the only way to reduce power sufficiently to land.