The newly upgraded Pathfinder Plus solar-powered remotely piloted aircraft was shipped from mainland USA to the Hawaiian island of Kaui on 6 May, where it will be tested on at least five missions over the next three months, some of which will include attempts to reach altitudes of up to 80,000ft (24,400m).

The AeroVironment aircraft is part of NASA's environmental research aircraft and sensor technology (ERAST) programme, aimed at developing vehicles for upper atmosphere science missions.

Pathfinder Plus is a hybrid vehicle combining the original Pathfinder and its planned successor, the Centurion. Flights are expected to begin in June with high altitude missions, followed in July by the US Navy support flights. Science missions, involving the dropping of weather-sampling "dropsondes" and possibly the use of an ultra-violet spectrometer, are planned for August, says NASA. Some flights in support of a naval exercise "-could be of extended duration", adds the agency.

Another ERAST aircraft, the Aurora Flight Sciences-built Perseus B, has meanwhile resumed flight tests with a successful sortie to 15,000ft from NASA's Dryden site at Edwards AFB, California. Progressive flight tests will extend the envelope in 15,000ft increments to 60,000ft. The fifth flight will carry a communications relay payload for the US Army in July.

Although details of the mission are scant, NASA says that "-the 6h mission at an altitude of about 40,000ft is intended to demonstrate the Perseus B's ability to function as an 'elevated antenna platform'."

The Perseus B's engine, which is triple turbocharged with four turbines in three stages (two in one stage) to offset the thin atmosphere, will eventually power the aircraft to altitudes above 60,000ft for long endurance missions of up to 24h. "At present, the endurance is about 8h," says NASA, which is also helping develop Perseus into a platform for extended duration atmospheric research missions, as well as a testbed for new ERAST technology concepts.

Meanwhile, General Atomics' Altus vehicle is expected to arrive back at Dryden around 19 May in preparation for its functional check-out flight following the replacement of its single-turbocharged engine with a dual-turbocharged powerplant. The Altus is designed to verify technologies that would be used for a long duration (12-72h), high altitude vehicle able to carry science payloads.

Additionally, the ERAST modified glider, called the Apex high altitude flight experiment, is being completed by Camarillo, California-based Advanced Soaring Concepts. The research vehicle is designed to operate at around 100,000ft. Its first flight is on track for late November/early December, says NASA.

Source: Flight International