The Pathfinder / Pathfinder-Plus is a lightweight, solar-powered, remotely piloted flying wing aircraft that demonstrated the technology of applying solar power for long-duration, high-altitude flight. It was literally the pathfinder for a future fleet of solar-powered aircraft that could stay airborne for weeks or months on scientific sampling and imaging missions.
Solar arrays covering most of the upper wing surface provided power for the aircraft's electric motors, avionics, communications and other electronic systems. Pathfinder also had a backup battery system that could provide power for between two and five hours to allow limited-duration flight after dark.
Pathfinder flew at an airspeed of only 15 to 25 mph. Although pitch control was maintained by the use of tiny elevons on the trailing edge of the wing, turns and yaw control were accomplished by slowing down or speeding up the motors on the outboard sections of the wing.
Pathfinder was designed, built and operated by AeroVironment, Inc., of Monrovia, Calif., the firm that developed the pioneering Gossamer Penguin and Solar Challenger solar-powered aircraft in the late 1970's and early 1980's.
During 1998, the Pathfinder was modified into the extended-wing Pathfinder-Plus configuration. On Aug. 6, 1998, the modified aircraft was flown to a record altitude of 80,201 feet for propeller-driven aircraft. The goal of the flights was to validate new solar, aerodynamic, propulsion and systems technology developed for the Pathfinder's successor, the Helios Prototype, which reached a sustained altitude of almost 97,000 feet in 2001, and other potential solar-powered derivatives in the future.
Essentially a transitional vehicle between the Pathfinder and the follow-on solar aircraft, the Pathfinder-Plus is a hybrid of the technology that was employed on Pathfinder and developed for the Helios.
