The ground resonance instability of advanced helicopters employing hingeless rotors is examined on a broad parametric basis and a variety of conditions affording inherent stability are determined. Moderate levels of blade internal structural damping in conjunction with typical landing gear damping and stiffness characteristics are shown to be highly effective as a consequence of the offsets of the virtual flapping and lead-lag hinges together with the tuning of the elastically flapping and lead-lagging blades of a hingeless rotor system. Size and scale effects are included by examining aerodynamically scaled designs which range in gross weight from 5120 to 48000 lb (2.32 to 21.8 tonnes). Closed-loop stabilisation of the ground resonance instability is considered by using a conventional helicopter swash-plate-blade cyclic pitch control system in conjunction with roll, roll rate, pitch and pitch rate sensing. This also is shown to be highly effective due to the control power inherent in the advanced hingeless rotor blade designs
Stability and control of hingeless rotor helicopter ground resonance
Stabilitaet und Steuerung der Grundresonanz eines nicht schwenkbaren Hubschrauber-Rotors
Journal of Aircraft ; 11 , 6 ; 333-339
1974
, 21 Quellen
Aufsatz (Zeitschrift)
Englisch
Hingeless variable pitch propeller hub, helicopter rotor wing and helicopter
Europäisches Patentamt | 2023
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