Japan has begun taxi tests of a high-speed flight demonstrator (HSFD) which will examine approach and landing technologies for a future reusable launch vehicle (RLV). The turbojet-powered HSFD-I is a 25%-scale model of the HOPE-X experimental spaceplane, work on which was halted in late 2000 when Japan changed the direction of its RLV research efforts.

The HOPE unmanned orbiter was designed for launch on Japan's H2A expendable booster, but the National Space Development Agency (NASDA) and National Aerospace Laboratory (NAL) are now embarked on a programme to develop a semi-reusable two-stage-to-orbit launch vehicle. HSFD tests will demonstrate technology applicable to the reusable first stage.

Flight tests of the Fuji-built HSFD-I are planned for later this year. They will demonstrate autonomous take-off, approach and landing. The vehicle will reach speeds up to Mach 0.7 and altitudes up to 35,000ft (12,000m). An unpowered second vehicle, HSFD-II, will be dropped from a balloon at 35km altitude to demonstrate the transonic regime. Six drop tests are planned between May and August next year at Kiruna in Sweden. A planned third demonstrator, HSFD-III, will be the first vehicle modified to demonstrate advanced guidance, navigation and control algorithms and reconfigurable, fault-tolerant avionics, says NASDA engineer Jiro Kouchimaya.

Japan's RLV plans bring together NASDA, NAL and the Institute of Space and Astronautical Science (ISAS), which are to be combined into a single organisation next year under MEXT - the country's Ministry of Education, Culture, Science and Technology. The RLV roadmap has two phases: the first decade, to 2011, involving fundamental technology work; and the second decade, to 2021, including development of an operational system.

Plans call for a reusable operation technology demonstration later in the first decade, Kouchimaya says. The demonstrator would combine a reusable horizontal take-off and landing first stage with an expendable second stage, and could be the precursor of a semi-reusable cargo vehicle capable of carrying small/medium-class payloads, he says. The first stage would have six liquid oxygen/liquid hydrogen rocket engines – upgrade dversions of the H2A's second-stage LE-5B.

Kouchimaya says the proposed operational vehicle would weigh 98t at take-off and would carry a payload of under 3t into orbit with a cost per launch of less than $15 million. The semi-reusable cargo vehicle could be developed into a five/eight-passenger suborbital transport.

Source: Flight International