| The existing tiltrotors all have a stiff-inplane hub to avoid the potential instabilities of groundand air resonance, and the dynamic researches about it are mainly focused on the instabilities of whirlflutter which limit the flight speed in aircraft mode. But the hub loads of stiff-inplane tiltrotors arevery heavy, in order to guarantee the hub strength, the weight of the hub is generally high, and theability to maneuver is limited. While soft-inplane rotor system not only can reduce the loads andvibration levels, reduce the weight of the hub but also can improve the handling qualities. But thepotential instabilities of ground and air resonance in addition to whirl flutter must be considered whendesigning a soft-inplane tiltrotor.In allusion to soft-inplane tiltrotor, the semi-span tiltrotor-wing aeroelastic dynamic analysismodel of Tiltrotor is founded in this paper by using the generalized Hamilton principle withconsiderations of aeroelastic couplings of rotor and the elastic wing. The effects of basic structuraland state parameters on the stability of tiltrotor in helicopter mode and transition mode are analyzed.A semi-span soft-inplane tiltrotor experiment model is designed by connecting lag hinges and lagdampers between the hub and the blade pitch hinges and some analysis on stability of the test modelare done. Some useful disciplines and conclusions are gotten from the analysis which can be used toprovide the guide to the dynamic design of soft-inplane tiltrotor. |
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