Abstract
A series of free-flight test campaigns with HTV-R re-entry capsules were conducted in JAXA Kakuda Space Center. These tests were conducted in the air driven two-stage light gas gun HEK-G with newly built 120 mm-diameter gun barrel, which can launch up to 110 mm diameter projectiles. The main purpose of this test was to obtain benchmarks for transonic instability of the HTV-R reentry capsule to compare with wind tunnel results or CFD calculations. Aerodynamic characteristics measurement of the projectiles was conducted with a miniature data-recorder and piezoelectric accelerometers on-board the projectiles. The JAXA in-housed miniature data recorder specially designed for the present test was small enough to be instrumented in free-flying projectiles with a maximum high-G resistance of 1000 G. The specifications of the recorders were (1) sampling rate of 100 kHz, (2) piezoelectric sensors (or piezoresistive sensors) with 8-channels, (3) sensitivity of 16 bit, and (4) recording duration of 1300 ms. The size of the recorder was 58 mm diameter x 50 mm height including batteries. A high-speed video camera was also used to observe the attitude of capsule shaped projectiles during free-flight. The projectiles were launched into open air at a flying speed of approximately 200 m/s, and captured on the soft-landing recovery cushion after a 30 m free-flight. All the projectiles used in this test campaign were recovered without any serious damage to the onboard instruments. Acceleration histories of pitching motion were successfully recorded with the onboard data-logger and high-speed video images that showed instable movement of projectiles.
