Keiji Komatsu

Airship Shaped Balloon Test Flights to the Stratosphere

In order to verify the design features of the SPF (stratospheric platform) airship prior to making the decision to fabricate a prototype SPF-1 (48 m balloon type), we conducted flight tests using four scaled airship-shaped balloons. Each balloon has a 22-m-long hull (maximum diameter 5.6 m), and its empty weight is about 25 kg. The balloons were launched in April and May 2002 and went up to an altitude of 18 km. These test experiences will provide good background information for further development of the SPF system.

VIBRATION TEST OF 1/5 SCALE H-11 LAUNCH VEHICLE

In order to predict dynamic loads on the newly designed Japanese H-11 launch vehicle, adequacy of prediction methods has been assessed by the dynamic scale model testing. The three dimensional dynamic model was used in the analysis to express coupling effects among axial, lateral (pitch and yaw) and torsional vibrations. Liquid/tank interaction was considered by use of boundary element method. The 1/5 scale model of H-I1 launch vehicle was designed to simulate stiffness and mass properties of important structural parts, such as core/SRB junctions, first and second stage Lox tanks and engine mount structures. Modal excitation of the test vehicle were accomplished with 100-1000 N shakers which produced random or sinusoidal vibration forces. Vibration response of the test vehicle were measured at various locations with accelerometers and pressure sensors. In the lower frequency range, correspondence between analysis and experiment were generally good. The basic procedures in analysis seem to be adequate so far, but some improvements in mathematical modeling are suggested by comparison of test and analysis.