The Thrill of Invention

A dedicated craftsman explores the invention of the airplane by recreating its predecessors.

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For Wright glider pilots, the rule is "lighter is better." As a result, Young's wife, Sue, had performed much of the flying for the IMAX film. Rick was so determined to fly for the "Nova" cameras that he lost 40 pounds in the two months prior to the 1997 trials. Jay, who had flown for the PBS program, was on leave from the Marines and accompanied the team just in case she was needed. Both father and daughter had plenty of opportunities to fly.

Young and his crew flight tested each of the reproductions in turn, and three years worth of experiments were collapsed into three short weeks of combined flight testing and flying. The letters, diaries, notebooks, and photographs of the Wright brothers came to life for those of us who took part in the events unfolding on Jockey's Ridge. There was a sense of having shared some of the excitement that the brothers had experienced and of having come to a new understanding of the process of invention.

1900:The brothers started their active experiments in Dayton in July 1899, when Wilbur first flew a biplane kite with a five-foot wingspan designed to test a new approach to roll and pitch control. By manipulating two pairs of strings tied to the leading edges of both wings, the operator could shift the upper wing in front of or back of the lower wing's leading edge, or twist the two wings "so as to present their surfaces to the air at different angles of incidence and thus secure unequal lifts on the two sides," as Orville explained.

From the outset, the Wrights thought like engineers. In 1900 and 1901, they relied on data from German pioneer Otto Lilienthal to calculate the wing area required to lift the estimated weight of their aircraft at a particular wind speed. The brothers planned to test their first full-scale machine as a kite. They hoped that they would be able to fly "for hours at a time" tethered to the top of a derrick and grow accustomed to the wing warping and the use of the forward elevator to control pitch, "getting in this way a maximum of practice with a minimum of effort."

The 1900 glider featured ash ribs bent to shape with steam, but even during the short service life of the aircraft, the ribs gradually flattened out. On the way to Kitty Hawk, Wilbur had intended to buy 18-foot lengths of spruce to serve as wing spars. But he could find no lumberyard that carried spruce in that length, and he was forced to settle for white pine spars two feet shorter.

"The covering of the machine was French sateen [a closely woven cotton], and it was put on the bias, so that no wire stays were needed to brace the surfaces diagonally," Wilbur wrote. Applied this way, so that the fibers aligned like cross-bracing wires, the fabric became a key element of the structure, holding the ribs and spars in place and distributing flight loads across the wing. The result was a tough, flexible wing capable of absorbing punishment that would probably break a more rigid structure.

The career of the first full-scale Wright aircraft lasted less than two weeks, from October 5 to 18. It was apparent from the outset that the wings developed far less lift than the calculations based on the Lilienthal tables had predicted. After one or two tries, the notion of tethering the kite to a tower was abandoned.

Since prevailing winds were almost never strong enough to lift the weight of a pilot, virtually all of the 1900 tests were conducted with the machine flown as an empty kite, or carrying a load of sand or chain. The brothers turned the situation to their advantage, measuring the actual performance of their glider and setting the stage for the creation of accurate aerodynamic tables.

They attached a grocer's scale to the kite line to measure the combined lift and drag force on the kite. They used an anemometer to record wind speed and measured the angle of the line to the horizontal with a clinometer. With that information, they calculated that their wings were generating only two-thirds the lift predicted by Lilienthal's table. They offered Tom Tate, the young son of one of their local helpers, some thrilling rides and thereby calculated the drag of an upright body. And they demonstrated the effectiveness of their control system with separate lines running to an operator on the ground.

To attempt some free glides, they moved to the nearest elevation, some small dunes known locally as the Kill Devil Hills, about four miles south of Kitty Hawk. Having lugged the glider part of the way up the slope of the tallest (100-foot) hill, they found the wind gusting to 25 mph. "As we hadÉno experience at all in gliding," Wilbur wrote, "we deemed it unsafe to attempt to leave the ground."

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