Dryden X-Press August 21, 1998
Pathfinder (Cont.)
Pathfinder-Plus is one of several high-altitude, long-duration aircraft being developed and evaluated under the ERAST program, part of NASA's response to growing scientific requirements for measurements at higher altitudes and durations than the current fleet of airborne scientific platforms permits.
The program is working to develop the technology for a future fleet of remotely piloted aircraft that could serve as high-altitude science and telecommunications platforms. Concurrent efforts in developing, miniaturizing and integrating sensors for science missions are under way.
Pathfinder-Plus flew twice previously this summer at PMRF. The goal of all three flights was to validate new solar, aerodynamic, propulsion and systems technology under development for the Path-finder's successor, the Centurion.
Centurion recently had a fit check and is about ready to fly.
Photo courtesy of Aerovironment
The Centurion is under construction by AeroVironment and is due to arrive at Dryden the second week in September.
A testbed for much of the Centurion technology, the "Plus" version is a hybrid of Pathfinder and Centurion. The Centurion is slated to begin low-altitude battery-powered development flights at Dryden in October, with high-altitude solar-powered flight tests planned for the summer of 1999. With a wingspan of 206 feet, Centurion is designed to reach and sustain an altitude of 100,000 feet for up to two hours.
Pathfinder-Plus' wingspan is extended from just under 99 feet to 121 feet by the replacement of the 22-foot Pathfinder center section with a new 44-foot-long section that incorporates a high-altitude airfoil designed for Centurion. The new center section is topped by more efficient silicon solar cells developed by SunPower Corp., Sunnyvale, Calif., that can convert 19 percent of the solar energy they receive to useful electrical energy. That compares with 14.5 percent efficiency for the older solar arrays that cover most of the surface of the middle and outer wing panels from the original Pathfinder.
In addition, the Pathfinder-Plus was powered on its record flight by eight more-efficient electric motors for the Centurion, two more than had powered the previous version of Pathfinder.
Pathfinder-Plus flight operations were conducted at PMRF to take advantage of a combination of Kauaii's low latitude and prevailing winds, which allow a good sun radiation angle for the solar arrays for longer periods than do more northerly locations.
Now that Pathfinder-Plus has met its milestone, program officials at Dryden and AeroVironment are focusing their personnel and resources on the upcoming initial flight tests of the Centurion at Dryden. The Pathfinder-Plus will temporarily remain in flyable storage in the hangar at PMRF so it can be available for science missions next year, if needed.
"We believe that focusing on Centurion optimizes the path leading to 100,000 feet (altitude) and eternal flight," said Bob Curtin, AeroVironment's Pathfinder project manager.
