Aerodynamic Interactions on Airbus Helicopters' Compound Helicopter RACER in Cruise Flight

With the pursuit of extending the flight envelopes of helicopters towards higher cruise speed, helicopter manufacturers increasingly have come up with non-conventional configurations in recent years. Amongst these, Airbus Helicopters' RACER is a compound helicopter equipped with a boxwing and lateral pusher rotors. In combination with the main rotor, these additional components determine the aerodynamic characteristics of the helicopter. Thereby, depending on the flight conditions, their individual performance is influenced by a variety of interactions. As the understanding of these interactions is vital for the evaluation of the overall system, the respective mutual influence of main rotor, wings and lateral rotors is analysed in this paper for cruise flight. For this reason, high-fidelity coupled aerodynamic simulations are conducted not only for the full RACER configuration but also for reduced setups omitting individual components in order to isolate the effect of these components on the helicopter's aerodynamic performance.