Constant Speed Propellors
Can anyone explain the intricacies of variable pitch and constant speed propellers to me?
I am only used to the simplicities of a fixed pitch propeller, where thrust is linked to RPM via the throttle - pretty easy to follow .
I can just about grasp the idea of a variable pitch propeller (increased angle of attack gives greater "forward lift" (=thrust), and presumably implies a reduced RPM, which decreases the fuel flow (i.e. like a high gear in a car?).
Now, if we have a constant speed propeller, what is keeping it at constant speed, and how do the throttle and propeller pitch come into the game?
In my simple mind, pitch X RPM = thrust, so for a given thrust we can either play with the pitch or the RPM. If the propeller speed is constant then we can only play with the pitch, so what is the throttle doing?