GB130702A - Improvements in or relating to Propellers. - Google Patents

Abstract

130,702. La ChevardiÞre de la Grandville, H. J. L. M. de. May 25, 1917, [Convention date]. Drawings to Specification. Screw and like propellers. - Laminated wood propellers designed particularly for aircraft are constructed so that their blades are free from bending, but are sufficiently elastic to allow the pitch to vary automatically during rotation. The neutral line, i.e. the line on which the centres of gravity of the various transverse sections are situated, is shaped so that if any desired point of it is considered which is in the effective part of the blade, and if the centrifugal force and the thrust, acting on the portion of the blade beyond the said point relatively to the axis of the propeller, is transferred to this point, the resultant of these forces is tangential to the neutral line and the two couples produced by the transfer are of equal and of opposite sign. Further, the neutral line is shaped so that if any desired point of it is considered which is in the effective part of the blade, the projection of the transverse plane passing through the said point, of the point of application of the trust acting on the portion of the blade situated beyond the said point of its neutral line, relatively to the axis of the propeller, is at a greater distance from the leading edge of the propeller than the said point of the neutral line. Methods for designing a propeller of this kind are described in the Specification at length. All the laminµ in the inactive part of the propeller above the neutral line may be of soft wood; the rest of the propeller is constructed from hard and very elastic wood laminµ.