A RE-ENTRY GUIDANCE LAW EMPLOYING SIMPLE REAL-TIME INTEGRATION

This paper describes a re-entry guidance law proposed for Hope-X, a Japanese winged re-entry vehicle, which is being developed by the National Aerospace Laboratory and the National Space Development Agency of Japan. The specific feature of the guidance law presented here is to employ simple real-time integration for generating a reference trajectory. This allows for variations in re-entry missions including abort flights. This guidance law is called "free-form method" because of its flexibility in the trajectory generation law. Generally, a guidance law employing a solution iteratively obtained by real-time integration requires high performance of an on-board computer, and is considered to have a risk of convergence. The free-form method has cleared these problems by simplifying the real-time integration and also by recent progress in computer technologies. The three-degreeof-freedom flight simulation results show the high capability of this method. Flexible guidance laws which already include optimization will mainly be employed for re-entry vehicles and space planes in the near future. The free-form method can be a baseline method for these guidance laws.