Optimization of Flight Stability of Water Rockets by Integrated Analysis of "Dynamic Simulation System" and "Robust Design"

Abstract

A water rocket is a rocket system that obtains thrust by injecting water with compressed air at high pressure and is usually manufactured using a pressure-resistant plastic bottle. It is compact and easy to manufacture, but technical elements and principles contained in water rockets are in common with the actual rocket system, and it is an appropriate system as a teaching material for science education and research. Since the rocket is a flying object, it is necessary to pay attention to the safety at launch and to set up the aircraft structure that stable flying even if made by anyone. For that purpose, numerical analysis of the flight trajectory to evaluate flight characteristics and quantitative analysis on flight stability are important. However, there are many empirical factors such as basic aerodynamic data required for orbital analysis and guidelines for aerodynamic design / structural design, which are important in achieving stable flight. In this research, we developed "Dynamics Simulation System" based on dynamic consideration and numerical calculation program on the flight distance, and analyzed the optimum flight conditions to obtain the flight stability. Based on the analysis results, by applying "Robust Design", factors which influence the flight stability with flight distance as the evaluation characteristic value are extracted, and approached the optimization of robustness flight conditions.