Study of water impact characteristics on the discharge door of a firefighting aircraft

The water impact characteristics of air tanker discharge doors during water discharge play an important role in firefighting aircraft design. To develop a door mechanism that opens rapidly without inducing significant structural impact on the airframe, it is essential to investigate the coupled effects of water impact and door motion. This study proposes an efficient and relatively high-fidelity simulation approach that combines Multibody Dynamics (MBD) and the Smoothed Particle Hydrodynamics (SPH) method to model the dynamic response of discharge doors during the water-discharge process. First, the proposed method is validated through a three-dimensional experiment, and the results show that the simulation accurately predicts the door’s motion trajectory. Subsequently, the dynamic responses of the door under different water payloads are analysed. The results indicate that the water impact load is not highly sensitive to the water payload. Finally, a parametric analysis is performed on a real firefighting aircraft door mechanism. The results demonstrate that the proposed simulation approach can effectively support the design and optimization of the door lifting actuator.