Split Torque Helicopter Transmissions with Widely Separated Engines

Abstract

A three-stage helicopter transmission of split torque type is shown to offer advances in a configuration that allows the engine axes to be widely separated and parallel. Three variants of the configuration are examined; one design with separated drive paths and four final-drive pinions is discussed in detail. This design offers 26 per cent less weight and 9 per cent lower losses than current production transmissions. Comparison is made with epicyclic type transmissions of similar rating that have been developed in the past decade.