Revitalising advanced rotorcraft research – and the compound helicopter.

I was honoured to have been selected to deliver the 35th Nikolsky Honorary Lecture. My graduate education at Princeton University owed much to the influence of Alexander A. Nikolsky, the second faculty member appointed to the Princeton Aeronautical Engineering Department in 1943(1). I arrived in 1963, only months after he passed away, but the memory of his presence was still vivid in the minds of his students and colleagues, as well as the professors who introduced me to rotorcraft(2,3). Bob Lynn, Senior Vice President at Bell Helicopter Textron, one of Nikolsky's most illustrious students, recalled the impact of his teaching in the 12th Nikolsky Lecture in 1992(4).This paper briefly reviews the history and development of compounds, tiltrotors and hingeless rotors. Largely through a quirk of history, the compound has been neglected for over three decades. The mission performance potential of the compound is re-examined based on basic aerodynamic principles and by surveying recent NASA and Army mission design studies. A rational case can be made that the compound is the preferred rotorcraft for intermediate-speed missions and that it can be a worthy complement to the helicopter and tiltrotor. Past US Army Aeroflightdynamics Directorate (AFDD) aeromechanics research in aeroelastic stability and prediction methodology is reviewed in support of advancing both conventional and compound rotorcraft. This paper describes ten research and development (R&D) initiatives to revitalise advanced rotorcraft research for both conventional and future compound rotorcraft. [ABSTRACT FROM PUBLISHER]