Rotary Wing Aerodynamics-Historical Perspective And Important Issues

The helicopter today enjoys a unique position in the field of transportation. This position is shown in Figure 1 which updates the view Gabrielli and von Karman reported in October 1950 with Reference 1. A most recent achievement--raising the helicopter speed record to slightly over 216 knots as Westland did--illustrates the potential that still exists in what many unfortunately considered to be a mature aircraft. To extract that high speed potential with a practical vehicle requires a clearer picture of today's technology and of the fundamental challenges to be met. And most importantly extracting the high speed potential of the helicopter requires a renewed vigor on the part of the aerodynamic members of the rotary wing community. Without a successful effort in the near term, maturing of the helicopter will, in fact, have occurred and the gap between helicopters and airplanes will be filled most immediately by the tilt rotor configuration. Therefore, this paper has been written primarily to encourage, stimulate and challenge those aerodynamicists who will soon solve the practical problems of high­speed helicopter flight.