Thirty years ago Francis Rogallo and his wife Gertrude invented a new kind of flying machine and the world said "So what?"

That was in 1948, when World War II was fresh in America's memory. Rogallo had been working for the government for 12 years, largely on military aircraft design. He wanted a change of pace.

"We felt that when the war was over it was time to get back to trying to improve aircraft that everyone could use." he said last week.

What came to Rogallo's mind then was a better kind of wing. "That's the difference between a surface buggy and a flying machine," he said. "The wings. That's what makes it fly."

For two years he pondered weight and mass and lift and drag. "We wanted an aircraft that would fly slowly. For that we needed large wings. That's what makes it fly.

"It occurred to me that by making it flexible instead of rigid, it might work."

Eureka! The Rogallo wing. In it's simplest form it's a plain square of stiffened cloth or paper with no stays or supports at all.Properly shaped in bat-wing form, it flies.

In a moderately complex form it's the hang glider, a toy that begat a sport. But no one figured that out right away.

Or any other use, for that matter. Rogallo took the new wing to his bosses at the National Advisory Committee for Aeronautics (later to become NASA). They told him he could keep working on it.On his own time.

From 1948 to 1958 Rogallo showed his design to the government, to military aircraft builders, to schools, "anybody I thought might be interested. But no one would seriously consider ti as a man-carrying aircraft."

Meanwhile, Rogallo and his wife and their four kids plugged away at home. They built models and tested them in a home-made wind tunnel in the attic. In a short time they came up with the Flexi-Kite, a simple, unstayed square of plastic laminate over cotton netting. They marketed it and sold several thousand.

But Rogallo had bigger ideas: powered, man-carrying machines; gliding cargo bearers; kites that could be attached to cars to carry them over streams and ponds.

He got a patent. He kept showing it around. But nobody listened, until Sputnik.

Suddenly his wing had a use. The space industry needed a way to get its hardware back to earth and the Rogallo wing, which offered directed flight plus soft landings, look good.

Engineers all over the country began toying with the wing. The space return didn't pan out, but the interest generated by the revival of the Rogallo wing started things happening and before long people were jumping off mountains with Rogallo wings strapped to their backs.

Rogallo, for one, still thinks his wing would have been a better way to land spacecraft than a dunk in the ocean under a parachute.

But, he said, "what they wanted was the quickest way and the parachuts was it."

By 1960 manufactures of military equipment were building powered Rogallo-wing, one-man gliders, and a picture of one was on the cover of Mechanix Illustrated. The Washington Post, in a 1961 article, listed the following likely benefits of the inventor's 13-year-old brainstorm:

". . . Combat personnel and cargo carriers, winged ambulances and utility vehicles for reconnaissance, wire laying and liaison missionns. Additionally, the flexible wing concept is ideally suited for a variety of drone applications including targets, decoys and as gatherers of meteorological data."

Other suggested uses at that time: air drops, radio controlled glide bomber carrying a warhead, a means of extending the range of cargo delivery and bombardment rockets.

None of that came to be. In fact, the only known uses that developed for the Rogallo wing have been the Flexi-Kite, still marketed by one of Rogallo's daughters, the hang glider and the parasail, used by sport parachutists as a directable, gliding chutes.

Out of all these suggested and actual developments Rogallo has made, he says, not a nickel. "We were just so anxious to get people to use the damn thing after 10 years that when the finally started experimenting the last thing we wanted to do was discourage them with our patent."

Now Rogallo is retired. He eased himself out of NASA in 1970, when the space program was the target of cost cutbacks and older employees were getting hints about leaving. He lives in a comfortable, new home outside Kitty Hawk, where aviation began.

He has two hang gliders in the basement, and once a month or so, when the weather's right, he drives the five miles down to Jockey's Ridge and jumps off the giant dunes with the rest of the glider pilots. Only John Harris, who runs the hang gliding school there, knows who he is.

"I'm really not very good," said Rogallo.

But he knows how it works.