A Flight-Dynamic Helicopter Mathematical Model with a Single Flap-Lag- Torsion Main Rotor
ARMY AVIATION SYSTEMS COMMAND ST LOUIS MO
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A mathematical model of a helicopter system with a single main rotor that includes rigid, hinge-restrained rotor blades with flap, lag, and torsion degrees of freedom is described. The model allows several hinge sequences and two offsets in the hinges. Quasi-steady Greenberg theory is used to calculate the blade-section aerodynamic forces, and inflow effects are accounted for by using a three-state nonlinear dynamic inflow model. The motion of the rigid fuselage is defined by six degrees of freedom, and an optional rotor rpm degree of freedom is available. Empennage surfaces and the tail rotor are modeled, and the effect of main-rotor downwash on these elements is included. Model trim, linearization, and time-integration operations are described and can be applied to a subset of the model in the rotating and nonrotating coordinate frame. A preliminary validation of the model is made by comparing its results with those of other analytical and experimental studies. This publication presents the results of research completed in November 1989.
- Operations Research