May 26, 1998. Copyright, 1998, Graphic News. All rights reserved

SOLAR-POWERED AIRCRAFT REACHES FOR THE RECORD BOOKS
By Oliver Burkeman

LONDON, May 26, Graphic News: SOLAR-POWERED aircraft capable of staying aloft at three times the altitude of civil aeroplanes for days at a time could be a reality by 2002, according to NASA scientists Ð and flights lasting months could follow soon after.
     The ÔCenturionÕ Ð currently being constructed by the California-based AeroVironment Inc Ð is scheduled to reach 30,000m (100,000ft) by the millennium and flight durations of four days by 2002. Double-sided solar panels covering 114sqm (1,230sqft) of the craftÕs 62.8m (206ft)-long wingspan will not only absorb light direct from the sun, but also collect rays reflected by the earthÕs surface. Energy will be stored for use at night, eliminating the need to carry traditional fuel or to stop for refuelling. 
     Scientists, military agencies and big business all have much to gain from a semi-permanent aerial platform, which could be used for observation, atmospheric monitoring and relaying sounds and images.
     But flights lasting more than a few days would require lighter fuel cells, a task requiring a further U.S.$20m of research investment. The hydrogen-oxygen cells are several times lighter than conventional batteries but need to weigh still less Ð work which NASA and AeroVironment hope to finance by involving other partners, possibly including the U.S. Defense Department, in the project.
     The ÔCenturionÕs predecessor, the ÔPathfinderÕ, broke the altitude record for propeller aircraft in July 1997 when it reached 21,802m (71,530ft). It is set to soar to 24,000m (80,000ft) above Kauai, Hawaii, in June Ð higher than any solar-powered craft has ever flown before.
/ENDS

Source: Aviation Week