These Carbon Fibre blades are available only from Bob Roach. The finished prop is 20 inches in diameter, and is a scale DC-3 prop. It is a variable pitch driven by a small electric motor and controlled through slip rings that are under the cover behind the prop hub. The prop motor turns 10,000 rpm and is geared approximately 22,000 to 1, so the blade rotation so the blade rotation is controlled by a FORWARD/OFF/REVERSE switch to adjust pitch. A governor could be fitted to make it automatic.