Dynamic Modeling of a Transport Helicopter for Internal Cargo Airdrop

This paper proposes a dynamic model for helicopter cargo airdrop process simulation. The overall method is used to incorporate the cargo motion into the general helicopter equations of motion, which simplified the complex cargo–helicopter contact model into a helicopter mass and mass center variation model. The trim and simulation of the airdrop process are performed by coupling the Newton iterative method with the Runge–Kutta algorithm. Simulation results of pilot maneuvering and helicopter attitude changes during airdrop are presented with different flight speeds (0, 20, 40, and 60 m/s) and different cargo masses (200, 400, and 1000 kg). The effect of cargo movement on helicopter stability is studied by the modal analysis method. Simulation results show that airdrop missions at low flight velocity with a large mass of cargo will increase the pilot’s control load and aggravate the helicopter’s attitude change. Additionally, both the longitudinal and lateral stability of the helicopter are deteriorated with the cargo’s rearward movement.