1. Project Sunrise

    2. Los Angeles California 1974

    3. Flight of the Worlds First Solar Powered Aircraft

    4. by

    5. Roland Boucher

The choice of propeller was limited by the motor speed (RPM) and the drive belt speed reduction available. The figure above shows the expected  efficiency of the chosen propeller to be 60% at MSL and 73% at 70,000 feet altitude.



The power available to climb is a function of both the time of day and the altitude. The Climb Power margins shown above assumed the propeller efficiency remained at 60% at all altitudes.