The Mauro Solar Riser is an American biplane

ultralight Ultralight aviation (called microlight aviation in some countries) is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional three-axis control aircraft with aile ...

electric aircraft that was the first crewed aircraft to fly on solar power. It was also only the second solar-powered aircraft to fly, after the uncrewed AstroFlight Sunrise, which had first flown years earlier.

Design and development

The president of Ultralight Flying Machines, Larry Mauro, created the Solar Riser by converting a stock UFM Easy Riser hang glider to solar power. Normally foot-launched, the Solar Riser had wheeled landing gear added. Power is supplied by a Bosch electric starter motor of connected to a 30 volt DC Nickel-cadmium battery pack taken from a Hughes 500 helicopter, powering a propeller through a reduction drive made from a timing belt and two pulleys. The battery was charged by a series of photovoltaic solar panels mounted in the top wing that provided 350 Watts of power. The solar cells were not sufficient to provide all power in flight, so all flights were made by recharging the battery on the ground from the solar cells and then flying using energy stored in the battery. A charge in bright sunshine for an hour and a half yielded a flight of 3–5 minutes. Because the battery power was enough to launch the aircraft for a soaring flight it was theoretically possible to launch on battery power, soar while the batteries are being charged by sunlight and then continue powered flight. The Solar Riser did not employ the most efficient cells available at the time and the upper wing had room for twice the number of cells to be installed. Early plans called for upgrading and increasing the number of cells so that sustained electric flight could be made using only solar energy and not battery power, but these plans were never completed.

Operational history

With Larry Mauro as the pilot, the Solar Riser made the first man-carrying flight on solar power at noon on 29 April 1979 at

Flabob Airport Flabob Airport is a small public-use airport located in Jurupa Valley, California, United States, in Riverside County, seven nautical miles (11 km) northwest of the central business district of Jurupa Valley, California. Location and his ...

Rubidoux, California Rubidoux ( ) was a census-designated place and unincorporated community in Riverside County, California, until July 1, 2011, when it became a neighborhood of the newly formed city of Jurupa Valley. The city is located within Southern California's ...

, near Riverside. The aircraft reached a maximum height of about and flew . A number of other flights of similar height and duration were flown, including demonstration flights at

EAA AirVenture Oshkosh EAA AirVenture Oshkosh (formerly the EAA Annual Convention and Fly-In), or just Oshkosh, is an annual air show and gathering of aviation enthusiasts held each summer at Wittman Regional Airport and adjacent Pioneer Airport in Oshkosh, Wisconsi ...

before the aircraft was retired to a museum.Glider Rider, June 1979 page 31 by Michael Jones

Aircraft on display

EAA AirVenture Museum The EAA Aviation Museum, formerly the EAA AirVenture Museum (or Air Adventure Museum), is a museum dedicated to the preservation and display of historic and experimental aircraft as well as antiques, classics, and warbirds. The museum is lo ...

- sole example

Specifications (Solar Riser)

References

External links