One of the downsides of the Aerovee is that you can’t hand prop it. The Aerovee uses magnatron ignition (like your lawnmower), the engine must be pulled over at a minimum speed of 250 RPM before the coil will even think about firing. Thick oil on a winter day or a heavy parasitic load may cause problems. If you try to hand prop, you could never get the RPM required to activate the Magnetron’s electronics.