A guy in Florida owns the pattern plane with the variable prop. He bought from Matt.

A constant speed prop would be cool but how would it be done? Hi-Johnson used to make one in the sixties for control line. It was set up with centrifigul force. One problem, the pitch would go flat with a dead stick and the plane would fall out of the sky. Hal DeBolt had tried it and wrecked has plane.

There is a guy in Europe making and selling variable pitch props. If memory serves the largest diameter is 12". I have the website somewhere in my old computer's favorites.