Well, the test pilot came out of it unscathed, but the crash of a cutting-edge unmanned prototype off Hawaii is a tragedy nonetheless for this fuel-cell test project. The solar-electric Helios Prototype flying wing was destroyed when it crashed into the Pacific Ocean in the U.S. Navy's Pacific Missile Range Facility off the island of Kauai on Thursday. The propeller-driven craft was flown by a ground-based pilot from the plane's owner, AeroVironment Inc., on a checkout flight to test the fuel-cell system. The fuel-cell system was needed to power the engine at night. During the day, solar panels kept the prop turning. The goal of Thursday's flight was to test the fuel cell under extreme conditions and to conduct a rapid shutdown of the cell and switch to batteries. It was the prelude to a planned 40-hour flight to demonstrate the long endurance of the aircraft. An accident investigation team will be formed by NASA, AeroVironment, and the Navy to determine the exact cause of the crash.