This is the concept, although the wings of any solar-powered aircraft would have to be much longer for the device to actually fly.
Illustration by Fotolia/Dario Lo Presti
Lockheed Missiles and Space Company, Inc. is developing a solar-powered aircraft to monitor crops for the United States Department of Agriculture. Although apparently still on the drawing board, the solar drone — called the High-Altitude Powered Platform (HAPP) — will likely be a long-winged affair with a single mid-mounted propeller driven by solar cells located on two vertical stabilizers and on both sides of its wing tips. These extremities will fold upward during the daytime to catch more sun and return to a more aerodynamic horizontal position at night, making it easier for the craft to run on stored power. With a wingspan of 160 to 300 feet and a total weight of somewhere between 1,000 and 3,000 pounds, the HAPP will probably cruise at a level of about 70,000 feet, above the zones of high wind activity.