Andrzej Jeziorski/TOKYO

Test Flights of the H-II Orbiting Plane-Experimental (HOPE-X) reusable space vehicle have been postponed from February 2001 until February 2004 because of a redesign and budget restrictions.

The HOPE team, led by Japan's National Space Development Agency and National Aerospace Laboratory (NAL), is carrying out a redesign which is likely to see the current configuration, with wingtip-mounted fins instead of a conventional fin for yaw stability, replaced by a conventional delta wing and single-fin configuration, similar to NASA's Space Shuttle.

According to sources close to the project, the weight of the structure required for the tip-mounted fins - particularly at the junction of the fins and the wings - placed an unacceptable limit on the payload. "The target weight [for the vehicle] is 10.5t empty, and the target payload is 3-5t," says NAL space projects and research centre director Nio Shinji. The vehicle is being designed to take standard freight containers for the International Space Station. The delay has also been driven by budget limitations.

Meanwhile, a Y9 billion ($756.3 million) budget has been allocated to build and fly two quarter-scale demonstrators to explore unconfirmed areas of the HOPE-X flight envelope: one to carry out approaches and landings and one to explore the transonic-flight regime. Fuji Heavy Industries has been selected to build the models under a Y3 billion contract. Preliminary design of the models began in April.

Source: Flight International