Sunday, April 29, 1979 was a watershed date for travelers in California for at least two reasons: First, it was the day that significant numbers of motorists all over the Golden State suddenly found their neighborhood service stations' gasoline pumps running dry. Second, It was also the day — at Rubidoux, California's Flabob Airport — that Larry Mauro made the world's first official flight in a fully controlled, solar-powered, man-carrying flying machine.
The aircraft, known as the "Solar Riser", reached an altitude of approximately 40 feet and quietly purred along for about one-half mile before gently settling back to earth. Another hop of substantially the same altitude and duration was made by the same pilot in the same machine later in the day ... but it was that first historic "stretching of the wings" that the 20 or so spectators who witnessed the event had made it their business to be on hand to see.
"What I've done," declared Mauro, who just happens to design and manufacture a biplane hang glider known as the "Easy Riser," "is take one of my gliders and add a set of landing gear to it. I then installed several panels of photovoltaic cells — which can convert the sun's rays directly into electricity — in the aircraft's top wing. When exposed to sunlight, those cells can feed 350 watts of 30-volt 'juice' into a little Hughes 500 helicopter battery that I've mounted behind the glider's seat. And the electricity stored in that battery can then be used to power a three horse electric motor which spins a pusher propeller that drives my little flying machine through the air."
Larry was quick to point out that, while his Solar Riser really and truly flies entirely on electricity made from sunshine, he considered his April 29 flights to be only "previews of coming attractions".
"The solar cells we're using are not really as efficient as some others currently on the market, and we can install at least twice as many of them on our machine as we've been using. We're also looking for a better battery. As things now stand, we have to charge for at least an hour and a half just to get a three-to-five minute flight. That's not as bad as it sounds, though, since it's theoretically possible for the rig as it is to take off, fly for three or four minutes until it catches a thermal, and then soar — shut down — for an indefinite period of time while the solar panels recharge the battery in preparation for a power assist to another updraft.
"Still, that's not the kind of flying I want to do. I want to improve this setup until we can regularly take off and fly around all day on nothing but the solar-generated electricity that we're producing as we buzz along."