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Clark

Flexible Wing

A great number of men and women made contributions to the world of airplane flight during the industry's early days in the 1930s through 1950s. Excitement ran high around this brave new world at the time, and more individuals wished they could have the opportunity to fly aboard or even pilot an airplane than there were opportunities to do so. Even as commercial flight began to take off, the expense was somewhat prohibitive for most.

Clark Engineer Francis Melvin Rogallo and his wife Gertrude aimed to make the dream of flying attainable for anyone. They helped thousands experience the sensation of flying freely in open air with their invention of the parawing in 1958; the creation sparked the activity that would come to be known as hang gliding. Not only did their research inspire an entirely new athletic activity and recreational industry, however, it also provided innovative new design principles later used by NASA and by aircraft manufacturers worldwide.

Born on January 27, 1912, Rogallo attended Stanford University, where he was among the first U.S. students to ever be awarded a degree in the new field of aeronautical engineering. He went to work as a researcher and wind tunnel manager at the Hampton, Virginia-based Langley Research Center, which was part of the National Advisory Committee on Aeronautics, or NACA. This organization would become the National Aeronautics and Space Administration, or NASA, in 1958.

While working for NACA, Rogallo became interested in building a simple, inexpensive type of aircraft that could be used recreationally. The agency did not share his interest, however, so he spent much of his spare time working with Gertrude, born in 1914, on an aircraft wing with a flexible structure, which, much like a parachute, would open and maintain its shape in the wind.

The Rogallos, who both enjoyed kite-flying, believed that wing structures could be made in a flexible fashion in order to conform to the motion of the wind, rather than the wind conforming to a rigid structure, as was the case with most aircraft designs. Using simple materials such as curtain fabric and cardboard, the Rogallos made a variety of small models that they tested in their home using a wind tunnel they built for the purpose. In 1948, the pair successfully tested a flexible v-shaped fabric and frame wing they called the "Flexi-kite," also known as the parawing. Its flexible structure created an airfoil shape while flying; they patented the design in 1951.

For several years the Rogallos' design was used in kites and indeed was an important innovation for kite enthusiasts then as it remains today. The inventors, however, had bigger plans for the Flexi-kite. Their invention succeeded in attracting NASA's attention in 1958, when the agency began examining the parawing for possible applications in space travel, specifically to return capsules to the sea after reentry into the atmosphere. NASA decided to use parachutes instead, however it did succeed in building a prototype known as the NASA parawing, or NPW, which garnered a great deal of attention in the mainstream media and among the general public.

Momentum began to build and finally the Rogallos saw their flexible wing concept take hold in the recreational arena. In the 1960s they had their first full-scale paragliding models built; they and their four children tested them on the windy beaches near their home in Nags Head, North Carolina. By the mid-1960s, hang gliding began to take off, both in the U.S. and in other nations, particularly Australia. Many who had seen Rogallos' designs in print publications had begun building their own versions of flexible-wing craft. The Rogallos decided not to defend their patent, instead allowing others to freely develop the design and further an exciting new sport. As a result, flex-wing-based kites and aircraft began to proliferate worldwide; ultralights, surfing and stunt kites began to appear as did experimental vehicles such as the "Fleep," or flying jeep.

The world's first hang glider meet took place in California in 1971; as of 2005, the U.S. Hang Gliding Association based in Colorado Springs, Colo., has nearly 10,000 members, who use a variety of parawing gliders built with today's new stronger, lighter fabrics and lighter composite materials. Today's craft allow hang gliders to travel dozens of miles in a single, non-powered flight.

[October 2006]

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