Paul MacCready, who has died aged 81, was known as the "father of human-powered flight".
In the 1970s MacCready, an American aeronautical engineer, found himself responsible for a $100,000 debt after he had guaranteed a relative's business venture which subsequently failed. He decided to try to win the £50,000 prize put up by the British industrialist Henry Kremer for a successful human-powered flight.
The prize had gone unclaimed for 18 years, but on August 23 1977 MacCready's Gossamer Condor - piloted (or rather pedalled) by Bryan Allen - made the first sustained, controlled flight powered solely by a human.
advertisementThe machine weighed 70lb and was constructed from aluminum, foam, piano wire and Mylar - a lightweight Polyester material. The seven-and-a-half minute flight covered a figure-of-eight course around pylons half a mile apart at Shafter, California.
Kremer then offered another prize, of £100,000, for the first human-powered crossing of the English Channel, and it took MacCready less than two years to claim it, with his Gossamer Albatross.
This contraption, also weighing 70lb, had a 96ft wingspan. Allen was again the pilot, with MacCready watching from a boat below. The flight lasted nearly three hours and covered 22 miles.
Paul MacCready, the son of a doctor, was born at New Haven, Connecticut, on September 25 1925. From the age of 12 he built model aeroplanes and gliders, and at 16 he qualified as a pilot.
After the war, during which he flew with the US Navy, MacCready took a degree in Physics at Yale and a doctorate in Aeronautical Engineering from the California Institute of Technology at Pasadena.
At the same time he took up gliding, winning the American championship in 1948, 1949 and 1953, and represented the United States in international competitions on four occasions.
In 1956 he became the first American to win the world championship. He also invented the MacCready Ring, used by glider pilots the world over to select optimum speed for the maximum glide.
MacCready established his first company, Meteorology Research, in 1951, and 20 years later founded AeroVironment, a firm which acts as consultants on environmental issues and wind power; it also designs remote-controlled electric planes, both as toys and as reconnaissance tools for the American military.
Among his other inventions, MacCready created the Gossamer Penguin, the world's first successful completely solar-powered aeroplane. In 1981 an improved version, Solar Challenger, flew from Paris to Canterbury, a distance of 163 miles, attaining an altitude of 11,000ft.
In 1985 the Smithsonian Institute commissioned MacCready to build a life-size, flying replica of a pterodactyl.
MacCready was also interested in designing surface vehicles with a view to conservation.
In 1987 he built the solar-powered Sunraycer to compete in a race across Australia; and three years later, in collaboration with General Motors, he produced the Impact, an electric car which could accelerate from nought to 60 in eight seconds.
In 1991 MacCready was inducted into the Aviation Hall of Fame. He retired as chairman of AeroVironment due to ill health on August 20, eight days before his death.
Paul MacCready is survived
by his wife, Judy, and three sons.