Pathfinder Plus in-flight over the Hawaiian island Ni'ihau on 17th June 1998. This is a solar- powered, unmanned, all-wing aircraft. The photovoltaic (solar) cells on the upper surface of its wing power eight electric motors, which turn the propellers (white). The aircraft, which is a modified version of the original pathfinder flying wing, has a 37 metre wingspan and weighs 317 kilograms. On 6th August 1998 Pathfinder Plus set a new altitude record for propeller-driven aircraft of approximately 24,500 metres. Pathfinder Plus is a prototype for an aircraft that could stay in- flight indefinitely carrying out scientific research and surveillance.