Flight Mechanics of the RACER compound H/C

Research on high speed helicopters has gained a new momentum in the last two decades. In the EU H2020 / Clean Sky 2 Program, Airbus is taking advantage of numerous partners across Europe to develop a new technology demonstrator named RACER, playing the cost-efficiency and simplicity cards. This paper presents the Flight Mechanics of this new compound helicopter technology demonstrator. Its excellent stability characteristics resulting from the implementation of optimized aerodynamic design features are introduced. More specifically, the results of the wind tunnel tests held in Filton UK are detailed, highlighting the benefits of the boxwing, the H-tail and the pusher configuration of the propellers. In the second part of this paper, the light is shed on the piloting aspects and the various similarities with conventional helicopters that facilitate the flight crew adaptation. The illustrated propellers management renews the successes of the X3 demonstrator and is endowed with new functionalities, including a full domain and low workload autorotation procedure.