1. Project Sunrise

    2. Los Angeles California 1974

    3. Flight of the Worlds First Solar Powered Aircraft

    4. by

    5. Roland Boucher

    P 13

Flight Test on Battery power at Bicycle Lake California

The first flight test was on battery power prior to the attachment of the solar cells. Sunrise was launched by a bungee cord to about a 20 foot altitude, then the electric motor was activated. The plane climbed to about 500 feet by the end of the runway. It then glided in a rectangular pattern turning left to fly crosswind, then left again to fly downwind, then left again on base leg and finally left again to final approach. On the first pass sunrise still had over 50 feet altitude when passing the operators located about 300 feet down the runway. The power-on portion was reduced gradually until an accurate measure of the average power required was established.  This Flight test on battery power was a complete success.

Flight Test on Solar Power at Bicycle Lake california

The solar panels which had been under construction at Heliotech in San Fernando California were mounted, and the electrical power verified with the aircraft in our parking lot. The Aircraft was returned to Bicycle Lake, a final full power check of Solar panel and electric motor was performed, and Sunrise made its first flight powered solely by incident sunlight on the flying surfaces. The weather was extremely cloudy that year even in the desert, and for some weeks we would wait in vain for clear skies and low wind. In all, 28 flights were made on solar power alone. Take off was sluggish, but once an altitude of a few thousand feet was achieved, the cells cooled down, power increased and Sunrise maintained a respectable rate of climb. The Telemetry and control system worked flawlessly and navigation by means of the sun compass was demonstrated, The final flight was made with cumulus clouds covering about 15% of the sky. The pilot flew too close to a cloud at about 8000 feet and Sunrise was destroyed in severe turbulence. We were disappointed that an altitude of 78,000 feet had not been achieved. However, there was no longer any doubt that Project Sunrise had demonstrated the feasibility of solar powered flight to extreme altitudes.