In my research on the forces acting on and influencing a single engine, non feathering variable pitch propeller's ability to change blade angle, I've come across a bit of a roadblock.
Aerodynamic forces try to move the blades into a coarse pitch, as the blade's centre of pressure is ahead of the blade's pivot point. That much is obvious and makes perfect sense.
What stumps me is the centrifugal twisting force. How does this send the propeller into a fine pitch?
Several sites talk about this concept, but only to the extent that they acknowledge it exists, and in what context it occurs. Here are some examples of the only relevant sections per site:
Centrifugal twisting force, being greater than the aerodynamic twisting force, tends to force the blades toward a low blade angle.
The centrifugal force acting on the blades tends to twist the blades such that the blade angle reduces. This force is somewhat opposed by the aerodynamic twisting force.
Source (Also comes with this image that has no explanation)
Centrifugal And Aerodynamic Twisting. Any asymmetrical spinning object generates a centrifugal twisting force, the propeller is no different with the force of its spinning action twisting the blades to a fine pitch.
I could go on.
Given that the force refers to 'centrifugal', I suspect centre of mass has something to do with it. If so, where is the centre of mass located? Forward, or aft of the pivot point? Seems like it would be slightly forward, given that a blade's airfoil shape would require more mass at the leading edge.