A nonlinear hub spring design and results of the subsequent flight testing as a concept to provide increased mast bumping safety margin for the UH-1H helicopter is presented. Although there is a need for additional testing, the hub spring is shown to provide an increased margin of safety by reducing main rotor flapping in all conditions tested. As a part of this effort, a hybrid computer program was verified as able to predict mast loads due to flapping stop contact. Using this program a parametric study of mast loads as a function of rotor flapping was performed in order to develop a design criteria to ensure that mast loads can be sustained during in-flight flapping stop contact. In addition, a comparison of the main rotor flapping predicted by the hybrid computer and the digital computer C81 program using elastic blades is shown, Also, an evaluation of U. S. Army helicopter tactics to determine which NOE maneuvers are susceptible to high main rotor flapping is presented. (Author)
Flight Test Evaluation of a Nonlinear Hub Spring on a UH-1H Helicopter
1981
159 pages
Report
Keine Angabe
Englisch
Aircraft , Hubs , Helicopter rotors , Springs , Nonlinear systems , Snubbers , Aviation safety , Rotor blades(Rotary wings) , Elastic properties , Stopping , Masts , Bending moments , Helicopters , Aeroelasticity , Computerized simulation , Hybrid simulation , Loads(Forces) , Parametric analysis , Flight maneuvers , Low altitude , H-1 aircraft , UH-1H aircraft , Hub springs , Flapping stops , Helicopter masts , Nap of the earth , NTISDODXA , NTISDODA
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