Preliminary design of suborbital spaceplane with LNG engines by a Japanese university start-up with the partnership of industries

Tokyo University of Science start-up SPACE WALKER Inc. is one of the start-ups in Japan founded in December 25th of 2017 aiming at commercial manned suborbital flight by developing three successive types of spaceplanes propelled by LNG engines with the partnership of Japanese aerospace, non-space industries and JAXA. The top management executives of SPACE WALKER Inc. harmoniously consist of a university professor, former executives and professional engineers involved in Japanese major space development so-called “Legacy Space”, and the young generation entrepreneurs so-called “New Space” having new business sense and challenging ideas. The first type of suborbital spaceplane, which performs vertical take-off and horizontal landing, reaches the altitude of more than 120km with the 100kg payload for the scientific mission such as micro-gravity experiment, higher atmospheric research and space observation. The second type of the suborbital spaceplane, which also performs vertical take-off and horizontal landing, separates the piggyback expendable rocket at the altitude of 40km with the Mach number of around 5 to launch a small satellite of 100kg into the Sun-synchronous orbit of 700km altitude. The third type suborbital spaceplane is manned with 2 pilots and 6 passengers performing horizontal take-off and horizontal landing like an airplane to reach the 120km altitude and provide weightless experience and earth watching services for space tourism. After preparatory meeting with the partnership industries and JAXA on the total development schedule, design team and total development cost etc. since November 2018, SPACE WALKER Inc. started the preliminary design of the first concept of suborbital spaceplane for scientific mission from April 2019. This paper introduces the current design of the suborbital spaceplane of scientific mission in the preliminary design phase, which resulted in the total length of 10.4m (body length of 9.1m) and the initial lift-off mass of 10tons propelled by 2 LNG engines with 77kN thrust per engine at sea level (100kN thrust in vacuum).