Aeroelastic considerations for torsionally soft rotors
Wayne R. Mantay, William T. Yeager, Langley Research Center, United States. Army Aviation Systems Command
National Aeronautics and Space Administration, Langley Research Center, 1986 - 20 pages
A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and six tip designs were tested on the torsionally soft blades. The designs incorporated a systemmatic variation in geometric parameters including sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. A track sensitivity study was also conducted at several advance ratios for both rotors. Based on the test results, tip parameter variations generated significant rotor performance and loads differences for both baseline and torsionally soft blades. Azimuthal variation of elastic twist generated by variations in the tip parameters strongly correlated with rotor performance and loads, but the magnitude of advancing blade elastic twist did not. In addition, fixed system vibratory loads and rotor track for potential conformable rotor candidates appears very sensitive to parametric rotor changes. (Author).
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ACR blades ACR/Swept Tip advance ratios advancing blade elastic Aeroelastically Conformable Rotor airfoil airload American Helicopter Society angle of attack Annual Forum Proceedings articulated rotors azimuthal baseline and ACR baseline and torsionally baseline blade baseline rotor Baseline/Swept Tip Fig blade elastic twist blade geometry blade loads blade torsional stiffness collective pitch conformable rotor concept Due to Tab elastic twist magnitude fixed system vibratory inboard Langley Research Center Loads and Performance Mantay NASA nose-up one-per-rev percent radius performance and loads PERFORMANCE RANK planform potentiometers propulsive force RANK STA ST RECTANGULAR ANHEDRAL rotor control rotor performance rotor shaft rotor track sensitivity shaft angle shown in Figure ST SA RA swashplate Swept Anhedral Swept Tapered system vibratory loads Test Conditions tip configuration Tip Geometry tip Mach number tip parameters tip shape torque torsionally soft blades torsionally soft rotor track sensitivity study trailing edge tab Transonic Dynamics Tunnel Wind-Tunnel Yeager