Dynamic Simulation of a Rotor System with Variable Speed

Abstract

Current Rotorcraft Developments like under the Future Vertical Lift Program in the US and RACER and NextGENCivil Tiltrotor in Europe deal with High-Speed Rotorcraft or Tiltrotor-/Tiltwing Aircraft which require a variable rotor speed either to adopt the rotor speed to high forward speed or to meet the different requirements of a rotor in Hover and Aircraft Mode of a Tiltrotor-/Tiltwing Aircraft. As the required speed range can not be covered by the turbine TU Munich (Germany), TU Wien (Vienna, Austria) and Zoerkler Gears (Austria) work in the transnational project “VARI-SPEED II” on a rotor system that can change the rotor speed via change of the ratio of the transmission (variable rotor speed with constant turbine speed). The project is based on the results of „VARI SPEED“ and the direct follow-up project. VARI-SPEED showed that a rotor speed variation performed by a transmission system is possible. The efficiency and the flight envelope of the rotorcraft can be improved by this technology. Furthermore, a method for rotor blade design in a RPM range was invented. VARI-SPEED II will now build up a model of the complete dynamic system from engine to rotor of a helicopter with a variable speed rotor. This model will be used for dynamic simulations of the system. A scaled model of the module that changes the speed will be developed and pilot studied in a simulator are planned to find out the characteristics of such a system. Aim of the project is to reach TRL 3 as basis for further development of the technology with interested OEM´s. The paprer gives an overview of the approach and shows first results of the modelling of the Gas Turbine, the Transmission, the Variator, the Rotor and the Rotor Control and shows the flight simulator where the model will be implemented for evaluation.