propellor pitch control question

[Kutscha]

On the Fw189, the tip of the spinner had some vanes on it. It is said that this had something to do with controlling the pitch of the prop.

Any know how the pitch control worked?

Thanks

[stephen f. polyak]

To achieve optimal operating performance, it’s necessary to vary propeller blade pitch angle with airspeed and flight condition. A low angle works best for high power takeoff and climb (at relatively low airspeeds), while a higher angle serves lower power cruise flight (at increased airspeeds) best. I suspect that the fixed pitch vanes on a Fw 189’s propeller spinner used associated aerodynamic forces (that varied with flight airspeed and/or engine speed) to rotate/turn the vaned spinner (independent of the propeller) and, via a joined mechanical advantage mechanism, regulate propeller pitch to "fit" the plane's airspeed/engine RPM. It appears a clever form of automatic pitch control.