An Automatic V.P. Airscrew: The Schwarz Two‐Position Hub with Completely Automatic Operation

THE Schwarz variable‐pitch airscrew hub is an automatic mechanism giving fixed positions to the blades ; at present there are two positions only, corresponding with the requirements respectively for take‐off and climb, and for normal flight. In either position the airscrew is stable, while the change‐over occurs automatically and positively in both directions at pre‐determined airscrew speeds. By limiting the requirements in this way, to the most important needs, it has been possible to simplify the design considerably and to make the mechanism independent of the effect of external disturbing influences, such as friction, displacement of centre of pressure, distortion of blades, etc.