Early experimental projects proved the concept sound and in 1973 Boucher turned his attention to the creation of a high-altitude solar-powered aircraft that would have unlimited endurance.
[5] Using commercially available off-the-shelf solar cells producing only 10% efficiency, Boucher calculated that his project would need to be able to fly on about 0.5 kW (0.7 hp).
The aircraft would use no batteries and, instead, would descend at night from its operating altitude to about 10,000 ft (3,048 m) at dawn, before solar energy was once again available for climb.
[6][7][8] Boucher saw the Sunrise as a proof of concept for a follow on aircraft that would be capable of remaining aloft for months at an altitude of 100,000 ft (30,480 m).
Due to their roughness the solar cells were only mounted on the aft two-thirds of the wing's upper surface.
[2]DARPA and Lockheed proposed a follow-on design to the Sunrise to be powered at night by batteries instead of just gliding.
Roland Boucher designed the second aircraft using higher efficiency solar panels that were more aerodynamically smooth.
[11] Roland Boucher had become physically exhausted from his work on the initial Sunrise and he suffered from congestive heart failure.
While in hospital he resigned from AstroFlight and sold his interests in the company to his brother Bob Boucher who continued work on the second Sunrise aircraft.
After recuperating, Roland Boucher returned to work at Hughes Aircraft on classified military programs.