Re-entry vehicle experiments planned for late next year
Japan's long-running research into a future space transport system will next year see automatic approach and landing tests of a subscale lifting-body re-entry vehicle. The Japan Aerospace Exploration Agency (JAXA) plans the tests for September-October at Taiki on Hokkaido island.
The Lifting Body Flight Experiment (LIFLEX) is the latest in a series of research projects to develop technology for a future spaceplane. The first project was 1994's OREX orbital re-entry flight experiment to test autonomous de-orbit and thermal protection systems. The capsule-shaped OREX was followed in 1996 by the launch of the HYFLEX lifting body on a sub-orbital trajectory to investigate hypersonic flight in the upper atmosphere.
The winged ALFEX was drop-tested several times in 1996 at Australia's Woomera range to demonstrate automatic landing of a re-entry vehicle. Powered subsonic approach and landing tests of a winged vehicle took place in 2002 at Christmas Island in the Pacific, and in 2003 by an unpowered transonic drop test of the subscale vehicle at Sweden's Esrange site.
While the winged vehicles previously tested were based on designs for the HOPE unmanned spaceplane proposed for launch by Japan's H-II booster, the LIFLEX is a wingless lifting body. JAXA says the design reduces the vehicle's mass and, although it has inferior flight performance in the atmosphere, has the advantages of lower heating during re-entry and greater payload capacity.
A configuration called LXB021 has been picked for the 20kg (44lb) LIFLEX test vehicle, which will be 1.6m (5.25ft) long with a 0.8m span. The unmanned vehicle will be dropped from a helicopter at 3,280ft, 1km (0.54nm) from Taiki's runway. Release speed will be 7,875ft/min (40m/s). The vehicle will follow a 45° glidepath to intercept a shallow 1.5° glidescope. Touchdown speed will be 6,400ft/min.
Blunt lifting bodies have poor lift-to-drag ratios, says JAXA, making it difficult to maintain stability and controllability at low speed. So automatic landing of the LIFLEX vehicle will be more difficult than in the previous tests, it adds.
The LBX021 configuration was selected over an earlier design, LBX000, which JAXA found unstable at low speeds, especially at high angles of attack. The main difference is that the LBX021 has a third, central, vertical fin. The wingless vehicle will have two rudders and four elevons for control.
Construction of the LIFLEX vehicle will be complete in March. "We will [flight] test it until it breaks," says JAXA. The vehicle will use a GPS-aided, microelectromechanical system-based inertial guidance system called Micro-GAIA, a laser altimeter, 2.4GHz wireless modem for telemetry, lithium ion battery for internal power, and flight control actuators from a large radio-controlled model aircraft.
Source: Flight International
