In 1970, MacCready guaranteed a loan for a friend who wanted to start a business building fiberglass catamarans. When the company failed, MacCready found himself $100,000 in debt.
Casting around for a way to deal with that problem, he recalled a cash prize offered by British industrialist Henry Kremer to anyone who built a human-powered plane capable of sustained, controlled flight.
"The Kremer prize, in which I'd had no interest, was just about equal to my debt," MacCready said. "Suddenly, human-powered flight seemed important."
To win the prize, he had to create an airplane that could take off on its own and fly a figure-eight, 1.15-mile course, clearing 10-foot hurdles at the beginning and end. Several people had tried; all had failed.
MacCready said he studied the soaring flights of hawks and vultures, calculating the amount of lift needed to keep the birds aloft and comparing that with what he knew about gliders.
He concluded that if he could triple the wingspan of a glider without increasing its weight, the power needed to keep it aloft in level flight would be only about four-tenths of one horsepower. He knew that a well-conditioned athlete could produce about that, and maybe a little more, for an extended period.
The spindly, translucent Gossamer Condor that resulted was crafted of aluminum tubing, plastic sheeting, piano wire and Scotch tape. It had a wingspan of 90 feet but weighed only 70 pounds. The pilot was Bryan Allen, a strong, slender bicycle racer who powered the single propeller by pedaling a drive chain made largely of old bicycle parts.
The Condor flew from the outset, but not well. However, because it flew so slowly and at such a low height -- about 10 mph and about 15 feet -- MacCready was able to improve its design through trial and error.
The bizarre aircraft crashed scores of times during flight tests, but Allen always emerged relatively unscathed. MacCready noted dryly that his crash-and-rebuild system worked all right for the Condor, "but it is not the way to develop airliners."
Finally, on Aug. 23, 1977, the Condor made a successful seven-minute flight over a figure-eight course laid out around the airport in the dusty San Joaquin Valley farming town of Shafter. MacCready claimed the Kremer prize and was celebrated as the father of human-powered flight.
"We're at last achieving a goal that man has had for thousands of years," he said.
