Pedaling Through The Sky:
MacCready Meets the Kremer Challenge
by Don Monroe (1978-79)
I wrote this article as an assignment for a feature writing course at the University of California at Los Angeles Extension in 1978-79, and it has not previously been published. It is based on my own observations and an interview with Paul MacCready. I have made only minor edits for use on this website. At the time of writing, the Gossamer Albatross flight across the English Channel had not yet been made.
When Bryan Allen flew the huge, flimsy Gossamer Condor on a 7 1/2-minute flight over a figure-eight course around two pylons a half-mile apart one summer morning in 1977, he fulfilled one of man's oldest dreams: flight under one's own power.
Although many individuals and groups had designed and built dozens of human-powered aircraft over the past 50 years, few persons had powered those aircraft through the air for even short distances and no one had come close to winning the Kremer Prize, which had first been offered in 1959. In essence, the rules for that prize required an unassisted takeoff, crossing a start-finish line at a height of 10 feet, flying at any height on a figure-eight course around two pylons a half-mile apart, and recrossing the 10-foot start-finish line. Those rules had become accepted as defining effective man-powered flight. The combination of the turning requirement and the distance requirement had defeated all previous challengers. Few had believed that the prize would ever be awarded.
While driving with his family on a vacation trip in August 1976, Paul MacCready had been reflecting on the performance of ultralight aircraft when it occurred to him that he could win the Kremer Prize by approaching the problem in a new way: creating an aircraft larger than any of the earlier designs while at the same time keeping it lighter, thereby reducing the power requirements to one-third horsepower, a level that an athlete could produce long enough to complete the required course. The aircraft could be designed so that repairs and modifications could be made quickly and easily. His ideas captured the imagination of everyone who heard about them and he soon had assembled a team of enthusiastic workers.
MacCready, in his early fifties, is an engineer, scientist, and entrepreneur. He is president of AeroVironment, a small company in Pasadena that deals with problems in environmental aerodynamics. He has been interested in aviation all his life, and when in his twenties won three national soaring championships and placed near the top in three world soaring championships before winning the world title in 1956, the first for an American. He made a major contribution to soaring by inventing the MacCready speed-to-fly ring, a device that appears on the instrument panel of virtually every high-performance sailplane. In recent years, he has been active in hang gliding and the ultralight end of the sport aviation spectrum.
The prospect of winning the £50,000 prize money (about $90,000), the largest in the history of aviation, was a strong lure to MacCready, but the project became so exciting and challenging, and working with the members of his team so much fun that he would have done it anyway. Although the project took a full year, months longer than he thought it would, MacCready always knew that his approach was sound and he would eventually succeed. His quiet confidence inspired all who worked with him.
The Gossamer Condor looks more like a huge winged insect than it does an airplane. As on the Wright brothers airplanes, the stabilizer is in front, the 12-foot propeller in back. The fuselage extends below the wing and an aluminum tube called a king post stretches about eight feet above the wing. The fuselage, wing, and stabilizer are covered with transparent Mylar sheet. The stabilizer is mounted at the end of a long aluminum tube, the bowsprit, extending from the wing-fuselage junction. A multitude of fine wires, used for external bracing, connect various points of the wing and the bowsprit to the top of the king post and the bottom of the fuselage. Power is provided by pedaling, just as on a bicycle. A special light-weight chain transmits the power to the propeller shaft at the top of the fuselage, just under the wing. The wing, with a 96-foot span, is comparable in size to that of a DC-9. The aircraft, without pilot, weighs only 70 pounds; a DC-9, a thousand times more. The ship looks fragile, and it is; flown at 10 mph, it needs near-calm conditions to fly safely.
On one Saturday morning at Shafter Airport, 10 miles north of Bakersfield, California, just before sunrise, the crew of a half-dozen men and boys were struggling to open the huge doors of a World War II hangar. MacCready was out on the runway on a bicycle, checking the condition of the wind, away from the influence of the hangar and other buildings. The wind was averaging only two miles per hour, and was steady, so MacCready was satisfied. He directed the removal of the Gossamer Condor from the hangar. Crew members untied the wing ropes and gently lifted the fuselage and placed it on the ground-handling dolly. Taking care to clear the hangar doors, the crew rolled the ship out of the hangar. Once outside, they turned the aircraft into the wind, and without delay, proceeded to the runway.
With the ship pointed down the runway, MacCready's 15-year-old son, Tyler, one of the two test pilots at that time, got in and tightened the straps of his toe clips. A helper resealed the Mylar access panel, and Tyler started pedaling to warm up. When he was ready, he started pedaling more vigorously and the Gossamer Condor quickly accelerated to flying speed, took off, and climbed to five feet above the ground. The propeller swished and the wing and fuselage surfaces rustled as the great aircraft passed through the air. After about one minute, having covered a few hundred yards, Tyler slowed his pedaling, and allowed the aircraft to descend to the runway. Helpers steadied the ship by grabbing the ropes hanging from the wing. MacCready walked up and asked Tyler about the feel of the controls and the power requirements.
Then Bryan Allen got in. Allen, 24, racing bicyclist and hang glider pilot, had become MacCready's primary pilot at Shafter after his predecessor, Greg Miller, had gone to Europe in the spring to race his bicycle. Allen's weight was ideal at 137 pounds and he also proved to have the necessary strength and endurance. Allen flew down the runway, and near the end executed a gentle l80-degree turn by tilting the tail and warping the wings. He then proceeded in the opposite direction nearly to the end of the runway when the wing spar suddenly snapped, and the aircraft slowly settled to the ground. The invisible wake vortex of a crop duster which had taken off moments earlier from the ramp adjacent to the runway had apparently struck the Gossamer Condor down.
MacCready's team repaired the ship with a few days labor. Less than six weeks later, Allen made the historic prize-winning flight.
After his success, MacCready felt a sense of relief, and thought he could then relax. He looked forward to taking time off. But then Henry Kremer, the British industrialist who had first offered monetary stimulation to man-powered flight, announced a new prize: £100,000 for the first successful human-powered flight from England to France, across the English Channel.
MacCready had already done some calculations, and he wanted to build a new aircraft. (The Gossamer Condor was to go to the National Air and Space Museum at the Smithsonian Institution.) With improved performance, it looked as though the new ship could do it. The prize justified an attempt.
MacCready and his associates spent the first half of 1978 studying materials and structures. The team began building the new ship, the Gossamer Albatross, in late spring. The Gossamer Albatross looked much like the Gossamer Condor, except that much of the aluminum tubing had been replaced by carbon fiber and the wing was designed to better maintain the intended airfoil shape. Additionally, the wing was narrower, therefore more efficient. It was generally a cleaner looking aircraft.
In mid-July, MacCready's pilots were flying once again. Bryan Allen, as well as Tyler and 17-year-old Parker MacCready, and even MacCready himself, made many flights during the calm conditions that prevailed on the Friday evenings and Saturday mornings of the next four weeks. But on one morning in mid-August, Allen experienced a problem with the wing-warp control and crashed. Allen suffered minor cuts and abrasions but the crash destroyed the fuselage and damaged other components of the aircraft.
Some of the steam has gone out of the project since then. The repair work has progressed slowly. A few design changes have been made. Some time has been consumed building the trailer necessary for transporting the aircraft when it is disassembled. When flying resumes, MacCready will be conducting two kinds of tests: dozens of flights to prove the integrity of the ship under a variety of conditions and maneuvers—turning, flying in crosswinds, etc.; and very careful tests under smooth conditions to verify that the power required is really low. He will also do some flying over water, perhaps from Cabrillo Beach, at San Pedro.
On a two-hour flight over the Channel, bad weather would be catastrophic for a fragile aircraft. MacCready believes that calm conditions exist a large part of the time during the months of May and June, when he hopes to make the attempt. During that part of the year, the water is colder than the air, which means the air should be stable, and there should be no turbulence. If the air were unstable, there would be turbulence, which would at best increase the power requirements and at worst break the aircraft.
A big question for MacCready is the effect of the wake of ships. Three hundred large ships plus ferries and other smaller vessels sail the Channel every day. He plans to do some testing with a light plane to find out how long it takes for the wake of a ship to disperse.
MacCready feels there will be little risk to the pilot on the cross-Channel attempt. He claims that should the Gossamer Albatross go in the water for any reason, the pilot should be out of the water in under 10 seconds. MacCready will use three chase boats for safety. He feels that if the pilot were to become too tired to pedal the entire width of the Channel one of the boats would be able to secure a towline to the aircraft and tow it to land.
The data so far indicate that the Gossamer Albatross requires about 0.25 horsepower, for steady flight. Bryan Allen can produce about 50 percent more than that for the two hours necessary for the 20-mile Channel crossing. According to MacCready, "There are many key factors; pilot power is not a crucial one."
The attempt to cross the Channel will cost about $200,000. Because of this, MacCready is seeking sponsorship. He hopes to find a sponsor whose products or services are compatible with his own interest in physical fitness. He has turned down a cigarette manufacturer. Without sponsorship, MacCready feels he would have little chance of success. He would have to go to England with only one aircraft (he would like at least two), a bare-bones crew, and little extra material and supplies.
To MacCready, one of the nice features of working on human-powered flight is that it doesn't have a practical application and he doesn't have to fudge one. It's not the start of a big recreation industry, but man-powered aircraft can be made so that they are trailerable, low cost (in time and money), and easy to fly. He envisions bike clubs building HPAs and flying on weekends. He thinks they would also be good for schools, to help teach construction techniques, aerodynamics, and physiology.
The aerospace establishment has accepted MacCready's success as a milestone in aviation, because it has extended the range of man's achievement. Professional associations, sport aviation bodies, and federal agencies have presented numerous awards to MacCready. "I don't want to appear blasé about awards," he says, "but I've got them all at home in a box."
by Don Monroe (March 31, 2010)
MacCready secured the sponsorship of DuPont. During the early spring of 1979, after having tried everything the team could think of to improve the performance of the Gossamer Albatross, they tried a new propeller design, from Prof. E. Eugene Larrabee, at MIT. That provided enough performance boost to allow making long-duration flights. MacCready and his team went to England in the spring of 1979. After waiting weeks for the promised good weather, MacCready saw an opportunity good enough to justify a crossing attempt on June 12. MacCready wasn’t sure it would be possible to actually complete the crossing. The team did have a backup aircraft, and another one under construction. As the photos on this website show, the flight was completed, having taken 2 hours, 49 minutes, much longer than the 2 hour maximum for which the team felt prepared. Bryan had long run out of water, and was flying on sheer willpower, with cramps in both legs.
All content on this site is copyright by Don Monroe unless otherwise noted.