Comparative Performance Measurements of Two Helicopter Blade Profiles in Hovering Flight

Abstract

Until relatively recently most designs of helicopter, including the Westland Wessex on which the tests described in this paper were made, used the NACA 0012 profile for the main rotor blades. Profiles designed specifically for helicopter rotor blades can effect a better compromise of performance characteristics in the widely varying conditions of incidence and Mach number in which they operate and one of a series of such profiles, RAE(NPL) 9615, developed and tested two-dimensionally has been used for the Westland Lynx. The changes relative to the NACA 0012 profile were conservative but were intended to give all-round improvements; that is to the shock-induced limits on the advancing blade, to the retreating-blade thrust limits and to the loading that could be sustained without shock-wave drag in hover.