Research Programs


Lynx Helicopter

Understanding the complex aeroelastic behavior of a helicopter remains a challenging task to rotorcraft analysts. The rotor aerodynamics, the rotor-wake fuselage interaction, the retreating blade stall, and the structural dynamics have to be included in an analytical model to accurately predict the rotor performance and loads. The calculated results must be correlated with experimental data, preferably with data from flight tests or full-scale wind-tunnel tests, to substantiate the accuracy of the analysis. Although a number of helicopter flight tests and full-scale wind-tunnel tests are documented in the literature, the majority apply to articulated rotors. Limited data from full-scale, soft-inplane hingeless rotors are available to the public.

NASA Ames Research Center and Westland Helicopters Limited (WHL) established a joint research program to document the flight tests of a hingeless Lynx helicopter and perform a correlation study with these data. The flight tests were conducted by WHL in 1985 to evaluate the performance and load characteristics of the Lynx-XZ170 helicopter equipped with rectangular metal blades. The helicopter was tested up to and beyond the retreating-blade stall boundary (defined by a limit of the vibratory pitch-link load). Test data consist of 27 steady, level flight conditions at different thrust levels and advance ratios. Rotor structural loads, performance, and flight conditions are documented in NASA Technical Memorandum 104000, "Performance and rotor Loads Measurements of The Lynx Helicopter with rectangular blades."

An additional objective of the joint research program was to examine the ability of both the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics developed by Johnson Aeronautics (CAMRAD/JA) and the R150 rotor analysis developed by WHL and the Defense Research Agency (DRA, formerly the Royal Aerospace Establishment), to correlate rotor performance, control settings, and blade and control loads with flight data up to and beyond the stall boundary. Out of the 27 flight conditions, 11 were selected for performance correlation and four for loads correlation. Calculated results compared with flight data are presented in the AHS 49th Annual Forum paper, "Correlation of the Lynx-XZ170 Flight-Test Results Up to and Beyond the Stall Boundary."

Related Publications:

Lau, B. H., Louie, A. W., Sotiriou, C. P., and Griffiths, N. "Correlation Of The Lynx-XZ170 Flight-Test Results Up To And Beyond The Stall Boundary," Proceedings of the 49th Annual Forum of the American Helicopter Society, May 1993.

Lau, B. H., Louie, A. W., Griffiths, N., and Sotiriou, C. P., "Performance and Rotor Loads Measurements of the Lynx XZ170 Helicopter with Rectangular Blades," NASA TM 104000, May 1993. Download

Point of Contact:

Benton Lau
NASA Ames Research Center
Moffett Field CA 94035-1000