595. Propeller and Rotor Driven V/STOL Power Transmission Weight Estimation Method

Paper

Abstract

This paper presents a method for estimating the weight of a V/STOL power transmission system. The method considers the power transmission system as the sum of the following basic components and presents estimating equations for each; shafts, bearings and supports, couplings, gear boxes, clutches and brakes.
The basic shaft is sized to the optimum D/t ratio, and weight per unit length is then determined.
Bearing and support (pillow block) weight estimating curves are established statistically while the maximum bearing spacing is determined analytically.
Equations are developed for both end and intermediate shaft couplings which for weight estimating purposes are assigned one of the following categories; Pure Flex Coupling, Ball Spline Flex Coupling, and Sliding Spline Flex Coupling.
Gear boxes are considered as a composite of several individual components (gears, shafts, bearings, etc.) The weight of each component is estimated separately by using statistically derived equations, and then summed to arrive at the total gear box weight.
Clutch and brake weight estimating equations are developed from statistical data on clutches used on both production and experimental aircraft.
It is felt that this method allows the flexibility required to estimate the light weight complex power transmission systems found in the present and future V/STOL type aircraft.