Month in the Patent Office: A Selection from Important Recently Published Aircraft and Aero Engine Specifications

A hollow air screw built up from sheet metal bent along a leading edge and joined along a trailing edge and having no internal stiffeners has a root end piece which is pivotally connected to the boss, whilst the blade is formed widest at the root tapering more or less uniformly to the tip. The sheet metal blade 2 is of aerofoil section and riveted or otherwise secured along the trailing edge. A channel‐sectioned end piece 9 is secured and riveted to the base of the root and bolted thereto is a hinge piece 13, drilled to take a bolt 14 for connection with lugs 15 on the boss 8. The single pin joint may be replaced by a double pin forming universal joint.