In order to acquire the technique of returning cargo from the ISS on orbit, researches on the HTV-R with a return vehicle are advanced. In this study, researches on the shock acceleration and the dynamic responses for the HTV return capsule's splashdown are conducted. The 6.8% reduction model of the return capsule was manufactured, and the free-fall drop test using a large-sized water tank was done. The dynamic behavior of the capsule model at the splashdown was clarified using both time histories of the measured acceleration by the accelerometer installed in the inside of the model and time histories of displacement, velocity, and acceleration obtained by carrying out image processing of the animation recorded with the high speed camera. Furthermore, a simple analytic method which carries out the simulation of the dynamic responses of the capsule at the time of water landing was proposed with the assumption that the return capsule was modeled as a rigid body. The validity of the analysis technique was verified by comparing calculation results with the experimental results.
