Retrotechtacular: The Gossamer Condor

For centuries, human-powered flight eluded mankind. Many thought it was just an impossible dream. But several great inventions have been born from competition. Challenge man to do something extraordinary, offer him a handsome cash incentive, and he may surprise you.

In 1959, London’s Aeronautical Society established the Kremer Prize in search of human-powered flight. The rules of the Kremer Prize are simple: a human-powered plane must take off by itself and climb to an altitude of ten feet. The plane must make a complete, 180° left turn, travel to a marker one-half mile away, and execute a 180° right turn. Finally, it must clear the same ten-foot marker. While many tried to design crafts that realized this dream, man is, at his strongest, a weak engine capable of about half a horsepower on a good day.

kremer-prize-courseBy 1973, no one had claimed the Kremer Prize, and the incentive was raised to £50,000. This was enough to catch the interest of [Paul MacCready], an aeronautical engineer living in California with his wife and two sons. [MacCready] was an avid gilder pilot who devised the theory behind the MacCready speed-to-fly ring. He also enjoyed hang gliding with his family, and while driving around sometime after one of these trips, he daydreamed about a design based on a hang glider that could win the Kremer Prize.

[MacCready] assembled a team of friends to help build what he called the Gossamer Condor. Constructed out of thin aluminium tubing, piano wire, Mylar sheeting, and tape, the Condor weighed just 55 lbs. and was easy to repair or alter in a matter of minutes. It was designed to have a 96-foot wingspan with a second, smaller wing for stability. One of [MacCready]’s sons, [Tyler] was chosen as the pilot due to his size and hang gliding experience. By Christmas of 1976, the Condor had taken many test flights and [MacCready] was confident he could win the Kremer Prize.

Around that time, he and the team got wind of a group of students in Tokyo who had built a plane out of balsa wood and handmade paper. It had already made a straight, mile-long flight in under five minutes. But [MacCready & Co.] didn’t know if it could turn. For that matter, they didn’t know if the Condor could turn, either. It was time to get serious.

paul-mccready-changes-condor[MacCready] hired [Greg Miller], a professional cyclist, to take over as pilot. He also made some changes to the Condor, loosening the strings a bit, tightening the Mylar sheeting, and embiggening the propeller with a manila folder. For all of [Greg]’s cycling prowess, the lack of control over the Condor was out of his . . . control. The Condor must be able to turn in both directions, or there was no hope of winning the Kremer Prize. The team added rudders and flaps here and there, but nothing worked. [MacCready] went so far as to make a mini model of the Condor, which he flew around in a swimming pool in order to better understand the effects of air mass on the square wing with respect to making turns. It was about this time that he decided to go back to the drawing board.

Three weeks later, they had completely re-imagined the craft and moved to a different airport with less wind. Now the pilot would be completely enclosed in Mylar. The new wing was stiffened with Styrofoam and had a new, more aerodynamic V shape. The changes paid off: in March of 1977, the Condor set the record for man-powered flight in a trip lasting just over five minutes. They tested it on a mock-up of the Kremer course, but the trial ended with a crash that bent some poles and tore some Mylar.

Repairs were complete in under 24 hours, but it didn’t fly as well as it had before the crash. [Greg] had to leave for Belgium to do professional cyclist stuff, and so [MacCready] found the Condor’s third and final pilot in [Bryan Allen], who was skilled in both cycling and hang gliding. As [MacCready] pondered the crash that twisted one side of the wing, he wondered how a twist could be advantageous. The final design contained a lever that the pilot could use to pull the wires going to one end of the wing, which aided turning control tremendously.

After several redesigns and over 400 test flights, the Gossamer Condor claimed the Kremer Prize on August 23, 1977. It currently hangs from the ceiling of the National Air and Space Museum at the Smithsonian, right next to the Wright Brothers’ plane and the Apollo 11 capsule. As for [Paul MacCready], his company, AeroVironment went on to capture the second Kremer Prize in June 1979 for crossing the English Channel with his second human-powered aircraft, the Gossamer Albatross.

[Thanks for the tip, Josuel]

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.

28 thoughts on “Retrotechtacular: The Gossamer Condor

    1. Some of his later creations were big, such as the Helios, an unmanned, solar-powered plane with 14 electric motors and a 200-foot wingspan that climbed to more than 96,000 feet, the highest altitude ever achieved by a propeller-driven aircraft.

      Some were small, such as his surveillance planes, the size of a man’s hand, that carried tiny TV cameras.

      Some didn’t work, such as a little plane powered by a hamster.

      “Hamsters are lazy,” he lamented.

      1. The Gossamer Albatross was displayed at the Pacific Science Center for a while (traveling exhibit, I imagine), and they had a “simulator” where you pedaled a stationary bike with a generator. If you pedaled fast enough you made a picture of the Albatross lift off on a computer display; pedal too hard and it rose too high. It wasn’t as difficult to do as I’d imagined, but maintaining a steady pace at the right “sweet spot” was hard, and there’s no way I could have done it for as long as it took Bryan Allen to make the crossing. He’s an overlooked hero of the 20th Century in my book.

  1. “man is, at his strongest, a weak engine capable of about half a horsepower on a good day”. At 745 watts per hp, there are more than a handful of pro cyclists who can generate 2 hp or more for probably enough time to fly this loop. (I am now a relatively weak old man and my PowerTap meter tells me that I am over 1 hp often.) A TdF cyclist can however generate a half-horsepower for much of their workday. That is power!

      1. Since a lot of readers here are probably nerds that don’t leave the couch and really don’t understand cycling power I’ll try to explain some of the stuff here because I think it’s interesting.

        There are ways to refer to power in cycling and relate one cyclists power to another. The main way is “FTP” = Functional Power Threshold.

        I’m amazed there is no Wikipedia article for FTP. It’s essentially the average power you can sustain for 1 hour on a bicycle. (Most people actually measure this over 20 min and calculate the hour average since it’s really painful to go that hard for a full hour.)

        If you want to know what a cyclists max FTP is, DON’T look at some group section of the tour de france. Because of drafting and tactics, they aren’t going full out around other riders. You want to look at Time Trial data, where the cyclists are racing by themselves and just the clock.
        One pro level data point is Bradley Wiggins, TdF winner, had around a 415Watt FTP in 2011 at the Paris-Nice. Which is pretty damn high.

        My FTP is around 175… which is crazy low :(

        The Gossimer Condor page doesn’t list the wattage needed for that plane, but the Albatross page does say 300W average.

        A really really fit and dedicated normal guy cyclist can do 300W FTP. You don’t have to be tour de france winner to do that.

          1. For which reason, in the cockpit enclosure of the Gossamer Condor, there was a small vent in front of the cyclist’s legs to cool them. I am also old enough to remember this flight, and that is one of the memories I take back from a documentary on it.

    1. And fuzzy. Don’t forget fuzzy. Made picking out the right lenses problematic when you couldn’t tell if your vision was poor or you were just seeing the fuzzy, out-of-focus world as it truly was.
      I was so happy when reality finally went to HD.

    2. It really was colorful, it’s just that some folks at Eastman Color had some short term goals.
      Very poor blue and green pigments with respect to lifetime.
      I have forgotten how long ago this was (like recently).

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