They have an aircraft at Old Rhinebeck with a rotary engine (not a radial engine) that they still fly. If I understood the explanation, there's no throttle - just ON/OFF. When they want to slow down to land, they'll cycle the engine on and off to slow the plane down. The cylinders and crankcase rotate with the propeller, so there's a lot of rotary inertia and no problem (they say) in restarting the engine. Very strange to hear it coming in - the engine will cut out for 5 seconds, run for 3 seconds, cut out for 5 seconds, etc..