When you work out numbers, you realize if you take a hang glider, sort of a 30-foot span, and keep the weight the same — sort of 50 pounds, 70 pounds, something like that — and swell it up to a 90-foot span, and the chord, increase also, the power goes down to one-third of what it was, and that brings it down to about point-four horsepower, which a person — a good athlete — can put out for some number of minutes. You didn’t need an elegant sailplane-like aircraft. You could have an ugly, dirty-looking hang glider-type plane, quick to build, as long as you made it giant without the weight going up.
That was the basic idea. There is one other idea that was essential, which was how to make something that big without the weight going up. The gimmick was that you did not need a structural safety margin that you need in a regular hang glider, which is going to fly at high altitudes, so if it breaks, somebody is going to get hurt. This was only going to fly at ten-feet altitude at ten miles an hour. If it broke, who cared? Nobody would get hurt at all. You could have it just on the very edge of breaking — no safety margin at all. Instead of cables, you use thin piano wire as a structural element. And so, with that idea and the basic idea of “large and light,” the problem was solved. I knew there would be a bunch of grunt work, engineering, to actually win the prize, but the idea that assured that the prize could be won was then in possession.