Variable pitch vs Constant speed.
Actually, there are differances between the two propellers. The constant speed prop found on majority of 'propeller bearing' aircraft, use this type of prop speed control. There is a 'goverenor' that looks after the set RPM. That speed, provided enough torque is supplied, will keep the prop turning at the slected RPM.
There IS another prop..and it is the Variable Pitch propeller. In the good old days, we were able to use a handle device, that looks much like a 'window crank' in car windows, to manually change the pitch angle of the propeller. With different power settings, the prop would turn at different speeds and constant manual adjustments had to be made in order to keep from blowing the jugs off the engine or keep the engine turning. I want to say that the aircraft was the old AilonAercoupe that had this option on it, but can't remember exactly.
Beta range is found on many Turbo-prop aircraft. Someone mentioned the C-130. And yes, it does have Beta..the percentage of torque conversion escapes me, but does work very well.
I also believe that the T'wotter has Beta range and can be used for short field work.
Hope it helps.
