GB119944A - Improvements in Screw-propellers. - Google Patents

Abstract

119,944. Crowther, D. S., and Routledge, W. Nov. 26, 1917. Screw propellers. -Each blade is built of a series of layers of wood, vulcanized fibre, papier - mÔchÚ, or the like substantially parallel to its helical surface. The strips a of wood &c. are made preferably with the outside strips, Fig. 1, tapering from end to end whereby the joints between the strips run diagonally across the propeller, and in practice the layers or strips are arranged as shown in Fig. 2, or the layers cross at right-angles. The strips or layers are placed in a former and cemented together to form a laminated propeller. Fig. 4 shows a layer b made of a single piece of wood slit longitudinally to form a series of adjacent strips a. A series of these layers are moulded on a former and secured to a wood boss having a central metal bush. The boss may be of aluminium and fitted with wings h, Fig. 9, which may in some instances take the form of frames i extending entirely around the edges of the blades. The blades are clamped, riveted, or screwed to the boss. The rear face of the blade is thickened by wood &c. layers n, Fig. 12, or by a shaped metal plate o, Fig. 13.