GENERALIZING HELICOPTER FLIGHT TEST PERFORMANCE DATA (GENFLT)

This paper discusses a comprehensive method for generalizing helicopter performance using data obtained from the primary types of performance tests (hover, level flight, climb, and descent). This method relates each type of performance data as the base line for low-speed level flight and vertical climb, and the level flight data as the base line for forward flight climb and descent. Momentum theory is used to derive generalized parameters for the power coefficient and velocity ratios, which in many instances eliminates the thrust coefficient as an independent test variable. This method results in a significant reduction in the number of flight test conditions needed for performance definition and illustrates where the test effort should be concerned. The test method allows independent identification of blade stall and compressibility effects as well as calculation of power required for any steady flight condition. The method is illustrated by use of several data sets which include level flight and climb comparisons of the AH-IR equipped with the standard Bell B-540 blades and the Kaman K-747 improved main rotor blades. The OH-58 data are used to illustrate the use of generalized performance in vertical climb.