Turbofan/Turboshaft Powerplant for Composite Helicopters

A concept for obtaining substantial amounts of shaft power from conventional two-spool turbofan engines will be introduced. The concept shows promise of alternatively providing rotor drive power and cruise thrust from the same engine for composite (stowed rotor) helicopter applications. The effects of varying several engine design features, including bypass ratio, compressor split, and variable geometry, on the amount of power available will be explored. Data on a specific engine will be used to investigate the installation, performance, and control characteristics of the engine in relation to the requirements of a typical composite helicopter.