HAWAII -- The solar-powered Pathfinder-Plus, an upgraded version of the original Pathfinder vehicle, reached a peak altitude of approximately 80,300 feet during a 15-hour flight in Hawaii. This was the highest altitude ever reached by a propeller-driven aircraft. The vehicle carried a simulated payload of 68 pounds.
The Pathfinder solar-powered aircraft was designed and fabricated by AeroVironment in the early 1980's to support a classified program. After its initial flight series, it was determined that the technology required had not reached a level where ultra long duration flight (many days) under solar power could be achieved. At that point the aircraft was placed in storage. In 1993, the aircraft was brought back to flight status by the Ballistic Missile Defence Organization and in 1994, transferred to NASA to develop science platform aircraft technology as part of the NASA's Environmental Research Aircraft and Sensor Technology (ERAST) Program.
A series of flights were planned to demonstrate that an extremely light and fragile aircraft structure with a very high aspect ratio (the ratio between the wingspan and the wing chord) can successfully take-off and land from an airport and can be flown to extremely high altitudes (between 50,000 and 80,000 feet) propelled by the power of the sun. In addition, the ERAST Project also wanted to determine the feasibility of such a UAV for carrying instruments used in a variety of scientific studies.