U.S. Patent Specifications

The method of making a hollow steel propeller‐blade which comprises cutting away two longitudinally‐extending adjacent zones from each of two diametrically opposite portions of a tubular blank, and leaving a greater wall‐thickness between the zones of each pair, one pair of zones being spaced from the other pair, to leave substantially full wall‐thickness between them, and cutting the blank to form face‐sections, each having substantially full wall‐thickness at its margins and a greater wall‐thickness along its mid‐chord line than in the cut‐away zones.