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Solar Hope Terry Drinkard

The first presentation was by André Borschberg. André is the CEO and test pilot of the Solar Impulse project, literally, a solar-powered heavier-than-air craft. Remember, our industry is only 107 years old. The first three powered heavier-than-air flights by the Wright brothers would easily fit within the wingspan of the Solar Impulse. The first flight by Orville was 120 feet, the second by Wilbur went 175 feet, and the third was Orville's at 200 feet. The Solar Impulse's wing span is 208 feet.

Another interesting historical parallel is that the Solar Impulse uses nothing but sunlight to generate about the same amount of power as the Wrights had available for their first flights. But we have learned so much since those first days. Solar Impulse did not spring forth fully formed like Athena from the head of Zeus. The roots of Solar Impulse lie deep within aviation history.

Setting the Way-Back Machine to the 17th Century

Yes, that's right. The 17th century; home of the Baroque cultural movement, the English Civil War and Cyrano De Bergerac. The dream of human-powered heavier than air flight goes back further yet, Ancient Greek mythology tells us of Icarus and his flight's involvement with the solar energy. The Greeks apparently had quite a negative view of the possibilities. But the dream of flight powered by the sun, supported by the sun, is fairly new, by comparison. Cyrano wrote a novel entitled Histoire Comique des Estats et Empire de la Lune, and Les Estats et Empire du Soleil in which the hero gathers the morning dew in flasks tied to his belt, harnessing what was thought to be the sun's power to raise the dew to raise himself above the earth and fly to the moon (there would be air to breathe all the way, he theorized). Of course, being Cyrano, he goes in the wrong direction. It was generally believed at the time that morning dew had a heavenly origin, sort of 'star tears', and that it would be drawn back into the heavens by the heat of the sun's rays. Our understanding of the physics of dew and the structure of earth's atmosphere has improved somewhat in the intervening four hundred years, but the dream of solar powered flight is still with us.

Dr. Paul MacCready

Back in the '80s when I was an undergraduate at Cal Poly, we had a number of human powered vehicle research programs. Dr. Patterson, from my department - aeronautical engineering - mentored two groups, including Neal Saiki's Da Vinci III human powered helicopter (which hovered for eight seconds at a glorius altitude of eight inches - I was there; I saw it). I, myself, worked on the human powered submarine (Subversion - we set the original speed record in 1989 just off Singer Island, Florida). We thought we were pretty good, but Dr. Paul MacCready's work was simply amazing. A dozen years before us, he won the Kremer Prize (the Kremer Prize tradition continues, but now they're called X-Prizes and Peter Diamandis is The Man - yes, yes, The Singularity University Peter Diamandis) for building and flying a successful human-powered heavier than aircraft, the famous Gossamer Condor. This is crucial technology for a solar powered aircraft.

Pre-MacCready

Before MacCready was Enea Bossi, an Italian aeronautical engineer who emigrated to the US. Actually Bossi studied math and physics in college, but he worked as an aeronautical engineer. He is credited with doing some of the preparatory work in human powered flight. He calculated that it should be possible to fly with .94 horsepower, which is very close to the upper limit of human
	The Pedaliante
capability (in Subversion, our primary motor guy could punch out 1.1 horsepower for a few minutes - underwater). In 1936, Bossi designed and built the Pedaliante for an Italian human-powered flight competition. The pilot was able to fly for 300 ft on his own power, and after a catapult launch from 30 ft, he was able to pedal the aircraft the full kilometer course (but did not win the prize because a catapult launch was not allowed).

Bossi's design had issues, not least was the dual propellers that he thought were required to counteract the torque that was so problematic in the ground-based bicycle tests, and the materials he had available at the time were heavier than what we have today. Pedaliante weighed in at 220 lbs. The Gossamer Condor weighed 70. Huge difference.

Enea Bossi is also kind of famous for teaching Giuseppe Bellanca (think Bellanca Aircraft) how to fly in 1908 at the age of 20 in an airplane he made himself. Giuseppe Bellanca taught Fiorella LaGuardia to fly in 1912 in an airplane he built himself - a parasol monoplane - and learned how to fly at Mineola, Long Island, New York. LaGuardia was the brilliant progressive mayor of New York City for a dozen years. The airport closest to the city is named after him.

Back to MacCready

In the '60s and early '70s, there was quite a bit of work done in human powered flight, but nothing could perform to the Kremer Prize rules (one mile figure-eight course, with a ten foot high threshold at the beginning and the end of the course). MacCready decided to form a team, which included Dr. Peter Lissaman the famous airfoil designer, to go after the Kremer Prize. Out of this determination came the Gossamer Condor, which won the first Kremer Prize in 1977. The Gossamer Albatross, also by Team MacCready, flew across the English Channel in 1979 to capture the second Kremer Prize. The book to read is Morton Grosser's Gossamer Odyssey.

MIT's Project Daedalus

Here comes the sun

After the success of the Gossamer Albatross, MacCready's team took a smaller back-up airframe and adapted it for solar power. It was dubbed the Gossamer Penguin. This was 1980, and the Gossamer Penguin was a testbed. It was ugly, but it worked. The follow-on aircraft, the Solar Challenger was much better, though at a full-up weight of 200 lbs including batteries and solar panels, it was still 10% lighter than Bossi's Pedaliante. We have made huge strides in materials technology in those 70 years. The Solar Challenger flew the English Channel. In fact, it flew from Paris to Manston, in the UK, 163 miles.

Two decades after the success of Daedalus 88, the Emily was brought out of retirement and refurbished by Aurora Flight Sciences as an unmanned solar-powered flight testbed. Aurora Flight Sciences was founded by Dr. John Langford, who just happened to have been the director of Project Daedalus for MIT.

These two programs laid the technological foundation for successful solar powered flight.

Solar Impulse

Solar Impulse has a wingspan of 208 feet

Standing on the shoulders of giants like Bossi, MacCready, Lissaman, and Langford, Bertrand Piccard, psychiatrist/aeronaut and CEO/pilot André Borschberg could see new possibilities and apply the new technologies that are continuing to emerge from the on-going materials research in the solar power industry. This is an amazing program and an amazing aircraft. The airplane has a wingspan of 208 ft, about the same as a 747-400, but weighs less than one quarter of one percent as much (to give the 747 its due, it is about 25 times faster). A challenging flight The airplane is challenging to fly, as André Borschberg told us. The control technique is so diferent that an autopilot had not even been designed before the 36 hour endurance flight. That's right. The solar powered Solar Impulse flew all day, all night, and part of the next day. That is tremendously impressive. The next step But that's not the end. There is another airplane in the works, HB-SIB, due to be
	Terry Drinkard discusses the Solar Impulse project with André Borschberg.
completed this year, with a wingspan the same as an A380, 262 ft. It's mission is as impressive as its size: to fly around the world. I hope that not only does the Solar Impulse team's success continue, but I also hope I'm at the presentaion following their triumphant flight. Solar Impulse at the Paris Air Show Solar Impulse will be making its first air show appearance as a special guest at this year's Paris Air Show, from the 20th -26th June at Le Bourget. Visitors will be able look closely at the aircraft on the ground, and each morning - so long as weather conditions are favourable - admire its majestic flying displays. details

Terry Drinkard is currently consulting on an aviation start-up. His interests and desire are being involved in cool developments around airplanes and in the aviation industry. Usually working as a contract heavy structures engineer, he has held positions with Boeing and Gulfstream Aerospace and has years of experience in the MRO world. Terry’s areas of specialty are aircraft design, development, manufacturing, maintenance, and modification; lean manufacturing; Six-sigma; worker-directed teams; project management; organization development and start-ups.

Terry welcomes your comments, questions or feedback. You may contact him via terry.drinkard@blueskynews.aero

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©BlueSky Business Aviation News | 14th April 2011 | Issue #121

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