Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Aerospace Engineering

The complex configuration of helicopter guarantee that the vehicle modeling, trim and simulation is significantly more difficult than fixed wing aircrafts. In this thesis, general expressions for the aerodynamic force and moment components acting on helicopter due to both main and tail rotors are driven by using the momentum theory and the blade element theory. These expressions are used in the rigid body equations of motion to build a general nonlinear model for single main rotor and tail rotor helicopter. This general model is used to get the helicopter response due to any set of control inputs, this process is denoted as direct simulation. Also, It can be used in control system design, studying the helicopter stability characteristics, and investigation of the vehicle handing qualities. The trim problem is solved at several flight conditions; any flight path angle, side slip angle and spinning rate. The inverse simulation; the process of obtaining the control inputs required by the pilot to achieve any maneuver, is solved by the differentiation approach. This approach is based on converting the differential equations to nonlinear algebraic equations which can be solved at each time step. The accuracy of this technique is improved by increasing the order of the differentiation scheme and decreasing the time step. The verification of the trim and inverse simulation results is achieved by supplying the resultant control inputs to the direct simulation code and the helicopter fly in the desired track

Issued also as CD