Preliminary design status of unmanned suborbital spaceplane with lox/methane engines by tokyo university of science's start-up with the partnership of industries: Part 2

Tokyo University of Science start-up SPACE WALKER Inc. is conducting commercialization of three kinds of unmanned and manned suborbital spaceplanes propelled by LOX/Methane Engines with the partnership of Japanese aerospace, non-space industries, JAXA, and university laboratories. This paper introduces the major changes in the preliminary design of the first concept of unmanned suborbital spaceplane called “FuJin” (project name), which performs vertical take-off and horizontal landing and conducts the scientific mission for micro-gravity experiment, higher atmospheric research and space observation to reach the altitude of more than 120 km with 100 kg payload under the maximum operational load of 6 G with the safety factor of 1.5 according to the airworthiness classification of acrobatic airplane. The fault tolerant design criteria of “FuJin” is as following: If one critical device or system fails, “FuJin” abort the mission to fly back and land on the run way. For the case of two critical devices or systems fail, “FuJin” terminates its flight by getting into spin motion to secure safety of the third parties on ground. The most recent “FuJin” design currently has the total length of 13.5 m and the initial lift-off mass 18.2 tons propelled by 3 LOX/Methane engines with 94 kN thrust in vacuum (77 kN at sea level) per each after the drastic design changes in the plane form. The design life of “FuJin” is 20 years based on the assumption of 50 launches per year by employing aircraft-like hard time, on-conditions and condition monitoring maintenance system. The design life of LOX/Methane engine is 2 years with minimum 100 launches including replacement of critical parts. The FAR field length required is estimated less than 1,500 m. The tentative candidate of spaceport locates at Taiki City, Hollaido Prefecture in Japan.