Improved Models for the Ground Handling Assessment of Navy Aircraft

摘要

The design requirements associated with catapult takeoffs and arrested landings can result in unique ground handling issues for Navy aircraft that operate within the carrier environment. More than a decade ago, models were developed to assess the ground handling deficiencies and proposed fixes for the primary Navy jet trainer. These models featured not only the dominant dynamic characteristics associated with the tires, but also the secondary effects associated with the aerodynamics. Recently, these models were refined and then used to evaluate the ground handling of a Navy cargo plane. Many ground handling force generators are involved with the landing rollout of this aircraft. These include the tires, engines (forward and reverse thrust), brakes, and direct and indirect aerodynamics. Furthermore, the pilot must use a variety of inceptors to provide inputs to each force generator including the wheel/column, rudder pedals and toe brakes, power levers, and nose wheel steering joystick. This results in a complex manual control task in the best of circumstances. A two degree-of-freedom yaw-sway "bicycle model" was used initially both in linear and nonlinear forms. This model, in which speed appears as a fixed parameter, was then extended to a three degree-of-freedom nonlinear yaw-sway-surge model in which speed is a state. Both models were simplified by neglecting the lateral load transfer. For the analysis step, the models incorporated newly acquired cornering (free roll) and combined cornering and braking tire test data. The new models were then used to evaluate several options designed to improve the ground handling of the subject aircraft.