A Generic Ground Dynamics Model for Slope Landing Analysis

This paper demonstrates a new approach for modeling and simulating landing gear systems. A generic ground dynamics model is developed in MATLAB-Simulink® environment and it is integrated to a non-linear 6-DOF helicopter model. Non-linear helicopter model is constructed in an in-house comprehensive analysis code, TAI Indigenous Rotorcraft Simulation (TIRS). Other than simulating the helicopter motion after touchdown, this model is also applicable for trimming the helicopter on ground, which is useful for determining landing and take-off capabilities of a helicopter on either a flat or a sloped surface. Slope landing and take-off analysis can be hard to simulate without a pilot in the loop simulation. However, trimming the aircraft for a specific maneuver can show whether the aircraft is controllable during this maneuver or not. In other words, this method can show whether the control ranges are adequate or not during the design stage, which is a troublesome task during preliminary design. Further, this model can be utilized to perform the slope landing mission task element (MTE) defined in ADS-33E-PRF. This paper presents the algorithms used for trimming the helicopter on a sloped surface, together with the dynamics of a generic landing gear. Trim and simulation results over a sloped surface are also provided.