Design changes have delayed windtunnel tests of the US Air Force Research Laboratory’s (AFRL) Micro-X, a demonstrator for a spaceplane-like reusable upper-stage vehicle that could be launched on an expendable booster or reusable first stage.

Windtunnel tests over the full flight trajectory are needed to validate the computational fluid-dynamics analyses used in design of the Micro-X and provide aerodynamic loading and heating data for subsystem development.

“The air force has spent several months refining the vehicle design, which resulted in delaying the test entry to spring 2007,” says AFRL windtunnel test programme manager Alyson Turri.

Data collected during the tests will be combined with future results and analytical predictions to characterise vehicle performance, she says.

A Micro-X scale model has already been tested in the AFRL’s subsonic aerodynamic research laboratory at Wright-Patterson AFB, Ohio to characterise its stability and control during the landing phase. Hypersonic aeroheating tests are to take place in 2008.

Several technologies needed for an operational vehicle based on the Micro-X have yet to be developed, and include reusable auxiliary power sources, accessible and maintainable avionics, non-expendable igniters and coking-free rocket engines.

Technologies for both first and upper stages are currently under development through the USAF’s Hybrid Launch Vehicle and Affordable Responsive Space (ARES) programmes. USAF’s Space & Missile Center is managing work on ARES, a potential first stage for the Micro-X.

Source: Flight International