Ground Dynamics Model Validation by Use of Landing Flight Test

[Abstract] In this paper, a new formulation for a ground dynamics model of a commercial two-engine helicopter is validated after touchdown. The inputs of the ground dynamics model are the velocities and angles at touchdown, and its outputs are the forces and moments produced by the ground on the helicopter. Expressions for forces and moments, which depend on the ground contact force, the friction coefficient between the skids and the ground, and the system stiffness and damping are determined. . The system stiffness and damping are defined between the touchdown point and the center of gravity in each of the helicopter’s degree of freedom. Expressions for the stiffness, damping and friction coefficients are validated for two kinds of landing situations: one-engine inoperative and autorotation. The ground dynamics of the Bell-427 helicopter model are then used to build and certify a level-D flight simulator.