NASA plans to conduct extra test flights of its small fleet of high altitude long duration air vehicles this year as it steps up environmental research work.
The Aero Vironment Pathfinder solar powered unmanned air vehicle, which is the most visible aspect of the US space agency's Environmental Research Aircraft and Sensor Technology (ERAST) programme, will attempt an 8h, 60,000ft (18,300m) mission during fiscal year 1998. Led by the NASA Dryden Flight Research Center in California, the ERAST project aims to develop aeronautical technologies that will lead to a new family of remotely piloted vehicles.
The aircraft would be used in upper atmospheric science missions to collect environmental data to assess global change. They could also carry telecommunications equipment, performing the function of communications satellites, for a fraction of the cost.
Other ERAST aircraft include the Perseus B, which was designed and built by Aurora Flight Sciences of Manassas, Virginia. The propulsion and performance testbed is designed to operate at 65,000ft for up to 96h.
The Perseus B's engine, which is double turbocharged to offset the thin atmosphere, "breathes" air surrounding the vehicle. It is being used to test engine concepts, lightweight structures, and flight control systems. First flown in October 1994, the Perseus B is scheduled to fly again at Dryden during the next few weeks.
General Atomics' Altus vehicle is being used to verify technologies that would lead to a long duration (12-72h), high altitude vehicle able to carry science payloads. The Altus' single turbocharged engine has been replaced by a dual-turbocharged powerplant. The Altus is scheduled to undergo check out flights beginning this month and resume its mission in mid-May.
The Apex research testbed will be built at Dryden by NASA engineers. NASA's Jennifer Baer-Riedhart says that critical design reviews are under way and that some components and structures have been built. The Apex's first flight is set for later this year.
A glider designed to operate as high as 100,000ft, the Apex would be hoisted up by balloon and released. After performing a pull-up manoeuvre, it would collect data during a 2h glide down through the atmosphere to Edwards AFB, California.
"The sole purpose of the Apex is to acquire research data for further development of other ERAST platforms. It is not something we would necessarily use for science missions like Pathfinder," says Baer-Riedhart.
Source: Flight International
