Ground Based Helicopter Simulation

This paper discusses recent experience of Sikorsky Aircraft with the software and hardware aspects of ground based helicopter simulations. Sikorsky has now accumulated a fair amount of simulation time on a six degree-of-freedom motion simulator, and this activity is also discussed. Simulation of the helicopter with ground based simulation equipment is paying off, but it has opened up new problems peculiar to this vehicle. While the economics and tangible output of simulation efforts are occasionally challenged, the highly coupled nature of the rotary wing machine makes helicopter simulations very beneficial, particularly during the design stage. Simulation difficulties unique to the helicopter arise because of its low speed and vertical flight capability. This paper addresses these difficulties, covering in particular the questions of how to keep the analytic sophistication within bounds, what to do about overall simulation response lags, how to provide adequate washout for best possible cues, and how to structure the overall simulation for the most satisfactory operation. With the development of an improved washout package, conversion of selected computations from digital equipment to analog equipment, improved actuator response, and the addition of lead networks, Sikorsky has obtained a satisfactory helicopter motion simulation and is now actively using this simulation in the development of all its new helicopters.