Multi-body Dynamics Modeling of Fixed-Pitch Coaxial Rotor Helicopter

In this study, a mathematical model of a fixed-pitch co-axial rotor unmanned helicopter is derived by using a multi-body dynamics modeling technique. First, we consider the helicopter as a rigid body system which consists of 2 rigid bodies. The velocity transformation method, which is one of the multi body dynamics technique, is applied to derive equation of motion of the helicopter. All the forces and moments impressed into the helicopter are derived in consideration of the aerodynamics of co-axial rotors. Derived mathematical model of the helicopter is verified by comparing the flight experiment data with model output. Finally, fundamental motion analysis using the model is conducted to establish the motion characteristics of the helicopter.