Eiichiro Nakano

Heat flux measurement of Apollo capsule model in the free-piston shock tunnel HIEST

This report presents the latest test results on the aeroheating of an Apollo capsule model under high-enthalpy flow conditions in the free-piston shock tunnel HIEST at JAXA Kakuda. The objective was to obtain benchmark data to validate JAXA in-house numerical simulation codes developed to predict hypervelocity flow fields such as the external flow around a re-entry vehicle. The SUS-304 stainless steel model had a maximum diameter of 250 mm and was equipped with 84 miniature co-axial thermocouples on its windward surface. Twelve thermocouples were also mounted on the leeward side of the model and were used to determine the establishment of flow around the model. Heat flux distribution around the model was measured in a high-enthalpy, high-pressure (i.e. high Reynolds number) flow at 0o and 30o angles of attack. Aeroheating characteristics were observed with a fully laminar boundary layer and with a transition boundary layer. To change the free-stream Reynolds number, stagnation pressure was varied from 14 MPa to 54 MPa and stagnation enthalpy was varied from 3.6 MJ/kg to 21 MJ/kg. The flow characteristics of the graphite nozzle throat, which was designed for high-enthalpy, high-pressure shots, are also discussed.

Aerodynamic Oscillation and Attitude Control Analysis for Reentry Capsule using OREX Flight Data and Wind Tunnel Data

Stable attitude control is essential for accurate reentry capsule guidance, and aerodynamic instability of a transonic region has been recognized as a key issue. To address this issue, we have been studying stable attitude control for lifting reentry capsule during reentry flights. As the first step of the study, we evaluated the aerodynamic stability and controllability of the Japanese ballistic reentry capsule named OREX (Orbital Re-entry EXperiment). The study compares reentry flight results with simulation results base on aerodynamic coefficients obtained from wind tunnel tests and aerodynamic damping coefficients modeled from wind tunnel tests and existing aerodynamic data-bases. We have also been analyzing the aerodynamic stability and controllability of a lifting reentry capsule by conducting attitude control simulations using aerodynamic damping coefficients estimated from the wind tunnel tests for dynamic stability characteristics. This paper describes the OREX system configuration, aerodynamic damping coefficients, reentry flight results, and a comparison of results obtained from flight data and simulations. Moreover we present the lifting reentry capsule model, aerodynamic damping coefficients estimated from wind tunnel tests, and comparison of results from wind tunnel test data and simulations.

On-orbit Demonstration Plan and Development Status of Electrodynamic Tether Technology on H-II Transfer Vehicle

Space debris has been steadily increasing. Cascading effect caused by the collision between the objects would worsen the situation further. To ensure the safety of future space activities, aggressive measures to reduce debris is needed. Since density of debris in the region of 800 km to 1500 km altitude is particularly high, the occurrence of cascade event can be a major obstacle for activities in Low Earth Orbit (LEO). To avoid this situation, JAXA is investigating a service system to capture a defunct satellite or rocket bodies, and remove them from this crowded orbit to waste orbit. JAXA is developing Electro Dynamic Tether (EDT) experiment system for on-orbit demonstration as a propulsion system. This paper presents system design, development status, demonstration plan, safety consideration to the ISS and reentry of EDT experiment system.