Two hours into the worst bike ride of his life, Bryan Allen is in trouble. His legs are cramping, he is dangerously dehydrated, and the French coast is still maddeningly far away. Worse, his “aircraft” is sinking — the turbulence over the water has robbed it of lift, and he is now pedalling a featherweight contraption barely a metre above the cold grey chop of the English Channel. Stop pedalling, even for a moment, and he goes in.

So he doesn’t stop. On 12 June 1979, powered by nothing but his own exhausted legs, Bryan Allen flew the Gossamer Albatross across the English Channel — the first human being to cross that famous water on muscle power alone.

An aircraft made of almost nothing

The Gossamer Albatross was the brainchild of Paul MacCready, an American engineer who had become obsessed with the problem of human-powered flight. His insight was almost philosophical: if a person can only produce about as much sustained power as a household lightbulb draws, then the aircraft has to be impossibly, ruthlessly light.

And it was. Built by MacCready’s company AeroVironment from carbon-fibre tube, thin plastic film and tape, the whole machine weighed about 70 pounds — less than the pilot. A huge, slow-turning propeller behind the cockpit was driven, by bicycle chain, from a set of pedals. The engine was a man.

The dream that wouldn’t die

People had wanted to do this for a very long time. Human-powered flight is the oldest aviation fantasy there is — Leonardo sketched flapping contraptions five centuries before MacCready — and for just as long it had looked impossible. The British industrialist Henry Kremer eventually put serious money behind it, offering prizes for anyone who could prove the doubters wrong.

Allen and MacCready took the first Kremer prize in 1977 with the Gossamer Condor, flying a figure-of-eight course. But the second prize was the romantic one: cross the Channel, the same stretch of water Louis Blériot had conquered by engine seventy years earlier, this time on human muscle.

Two hours and forty-nine minutes of agony

The crossing was supposed to take about an hour. It took nearly three. Headwinds slowed the Albatross to a crawl, the heat sapped Allen of fluids he couldn’t replace, and near the French shore the air turned rough and the aircraft began to settle toward the waves. He came within seconds of giving up. Instead, somehow, he found a little more in his legs, climbed back to a survivable few feet, and pedalled the last stretch to Cap Gris-Nez.

When the wheels — well, the single wheel — touched French soil, Allen had done what da Vinci only dreamed of and won the £100,000 Kremer prize. The Gossamer Albatross never needed to fly again. It had already answered the question humans had been asking for five hundred years: yes, with nothing but your own two legs, you can fly across the sea.

Sources: Smithsonian National Air and Space Museum; AeroVironment; Wikipedia; Caltech Magazine.