This paper presents an approach on contact force simulation and subsequent reduction during robot-assisted landings of unmanned aerial vehicles. The considered landings are performed using a serial kinematic industrial robot with a custom gripper. The goal is to investigate robot-assisted landings for heavier and larger combinations of unmanned aerial vehicles and industrial robots. For that, a multi-body simulation including all involved subsystems is developed, enabling the analysis of the physical interaction between robot and aircraft during the robot-assisted landing. The simulation features contact force calculation capabilities, applying the linear Kelvin-Voigt contact model. The results show an initial rise in contact forces that might pose a structural problem for robot or aircraft. Therefore, the paper proposes an approach on contact force reduction by reducing the relative speed between UAV and gripper at impact. The multi-body simulation is verified based on exemplarily contact situations. By reducing the impact speed, the contact forces are reduced considerably.