ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF FLUTTER AND DIVERGENCEHN L.
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON D C
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THE RESULTS ARE REPORTED OF AN ANALYTICAL AND EXPERIMENTAL STUDY OF FLUTTER AND STATIC DIVERGENCE OF A RIGID CONICAL SHELL MOUNTED ON SPRINGS THAT PERMITTED FREEDOM IN VERTICAL TRANSLATION AND PITCH. The test program was conducted with air as the test medium in the Langley 9- by 18-inch supersonic aeroelasticity tunnel at Mach numbers 1.64, 2, and 3 and with helium in the Langley 8-inch hypersonic aeroelasticity tunnel at a Mach number of 6.83 and in the Langley 24-inch hypersonic aeroelasticity tunnel at a Mach number of 15.4. Flutter calculations were made based on several slender-body theories for approximating the oscillating aerodynamic forces and moments acting on the cone. Good agreement with experimental results was obtained for the quasi-steady aerodynamic approaches of Van Dyke and Von Karman at low supersonic speeds and for Newtonian theory at hypersonic speeds. Pitchaxis position and translation-to-pitch frequency ratio had a pronounced effect on the flutter speed boundary, particularly near a frequency ratio of 1. No flutter was encountered experimentally or predicted analytically when the center of gravity of the model was ahead of the pitch axis. Author