GB500679A - Improvements in and relating to screw propellers - Google Patents

Abstract

500,679. Screw propellers. BUGATTI, E. March 10, 1938, Nos. 7534 and 7535. Convention dates, March 10, 1937 and Feb. 28, 1938. [Class 114] A screw propeller wherein each blade root and a blade carrier on the shaft have interspaced projections which are attached to one another by means of a plastic and resilient material such as rubber composition between these projections which serves as the sole means for retaining the blade in position. The boss W has sockets'V in which are accommodated the roots U of a blade H. The root U has a metal sleeve Q which is provided with key-like projections R and the interior of the socket V has corresponding projections between which is disposed a rubber sleeve T. The projections S and R alternate both in the direction of the length of the blade and around the periphery. The sleeve part Q may be made in two parts to facilitate assembly. In an alternative form the blade root and the inner part of the socket have screw-thread blades between which is a space to accommodate a thin layer of rubber, but in the event of the rubber wearing there is sufficient interengagement of the threads to prevent the blade being drawn out by centrifugal force. Where the blade root is not of circular section but of streamline form then the screw surfaces are replaced by parallel grooves without pitch. The rubber interlayer may be moulded and vulcanized in position and may then be used to resist torsion also in variable pitch propellers. Specification 396,578, [Group XXXIV], is referred to.