Vibratory Load Prediction Of Cyclicless Pitch Rotor Of Side-by-Side Helicopter

In this thesis, the research object was a new side-by-side helicopter. With the rigid rotors, the hub structure was simplified without flap and lag hinges. And the cyclic pitch control was omitted. With the new universal joint hub, the control method of the new side-by-side helicopter was more simple than the conventional single-rotor helicopter.In this thesis, based on the moderate deflection beam theory developed by Hodges and Hamilton’s principle, the rotor structure model of the side-by-side helicopter was established. The blade aerodynamic load was calculated based on the quasi-steady aerodynamic model and the induced velocity model of rotor was the uniform inflow model. The blade was discretized into a number of beam elements. Each beam element consists of fifteen degrees of freedom. To show the coupling effect of the universal joint movement and the blade movement, the two degrees of freedom of the universal joint was added by the variation of kinetic energy. With the blade equations of motion on the basis of Hamilton’s principle, the method was used to solve the response and the vibratory load of the blade section. Hub load was obtained by the superposition of the blade root load.The rotor dynamics model was verified by examples. For the new side-by-side helicopter, rotor loads were predicted and analyzed in hover and forward flight.