This study aimed to improve the stowage efficiency of solid deployable reflector antennas by proposing a novel structure, the deployable scissor-supported petal reflector (DSPR). Traditional petal-type antennas have prioritized reducing stowage width over height, limiting compactness. To address this, we introduced scissor structures that allow the reflector surface to fold both radially and circumferentially. This concept enables simultaneous reductions in both stowage width and height. Theories and constraints essential for the design were derived, and a DSPR example was developed. Calculations showed expected stowage efficiencies of 0.32 for width and 0.27 for height, demonstrating significant improvement in height stowage efficiency compared to prior studies while maintaining competitive width stowage efficiency. CAD modeling verified these efficiencies and ensured no component interference in the stowed state. A 3D-printed prototype validated the compact stowage concept but revealed challenges in mechanical implementation. The DSPR design concept provides a promising solution for compact solid deployable reflector antennas, offering a notable advantage in height stowage efficiency compared to existing technologies.

Focusing a spherical shock wave formed by laser ignition in an elliptical cavity can initiate detonation. To clarify the effect of the detonability of premixture and shock intensity on detonation onset, laser ignition experiments were conducted with stoichiometric ethylene–oxygen premixture at the initial pressure of 5–200 kPa and laser emission energy of 50–150 mJ. The flow field was visualized by high-speed schlieren imaging. As a result, four different types of flow field were observed: moderate initiation, rapid initiation, general flame acceleration, and shock-only flow field. In the moderate initiation case, shock-flame complexes engulfed the leading shock wave and collided to cause a local explosion. In higher initial pressure, rapid detonation onset was observed when a local explosion occurred behind the leading shock. In the failed cases, although the initial shock, the reflected shock, and the combustion wave were observed, except in the shock-only case, a local explosion did not occur after the triple-points’ collision. Each case was classified as success or failure, and the success/failure distribution was compared with the critical energy of direct detonation initiation.