The Thrill of Invention
A dedicated craftsman explores the invention of the airplane by recreating its predecessors.
- By Tom Crouch
- Air & Space magazine, May 1998
(Page 6 of 7)
"The boys walked in unexpectedly on Thursday," their sister Katharine wrote to their father on August 26, 1901. "[They] haven't had much to say about flying." Small wonder. But if their second glider had been something of a disappointment, it had also taught them a great deal about the movement of the center of pressure and underscored the need for a wing structure that would not deform under flight loads. It further confirmed that there was a problem with the data used to calculate performance and also revealed a dangerous flaw in the control system.
In order to demonstrate the way in which the Wrights discovered problems with aircraft design that enabled them to move forward, Young decided to build the original version of the 1901 glider. The Wright collection of glass plate photographs contains nine images of the glider, none of which show the aircraft as it was originally constructed. Since the modifications are obvious, however, Young had no trouble reproducing an aircraft that had not been captured by the camera -- in fact, a machine that no one has seen since 1901. In the interest of simplicity and safety, and because it would have no technical impact, he substituted the hip cradle wing warping control of the 1902 glider for the foot control actually employed on the 1901 glider.
Jay, who made the first tethered flights with the machine, discovered that, like Wilbur, she had to move well back of what would seem to be a natural flying position in order to keep the 1901 machine balanced. Young's early glides with the machine were also a replay of Wilbur's experience, complete with a landing hard enough to damage the structure.
With some worrisome flight test experience under their belts, the cause of the problem was as apparent to The Wright Experience team as it had been to Wilbur and Orville. As the aircraft sits flat on the ground headed into the wind with no flight load, the ribs deflect as much as an inch and a half at the midpoint between the spars. You can send a distorting wave moving the length of the wing simply by tapping your hand on top of one wingtip. It is one of those perfect cases in which the "Nova" crew can film the problems that beset the airplane in the air, then provide viewers with a close look at the cause: those flexible ribs.
1902: The 1902 Wright glider was the product of two years of flight testing and a few weeks of priceless wind tunnel data gathered in the back room of a bicycle shop in Dayton, Ohio. The machine had recognizably different proportions than its predecessors. It was also the first Wright glider to sport a rudder.
Determined to calculate performance accurately, the Wrights designed and built a wind tunnel and a pair of brilliantly contrived aerodynamic balances, then gathered the data with which to prepare their own tables of lift and drag coefficients. During the fall and winter of 1901, the tunnel also enabled them to study the most efficient proportions for a wing, the impact of varying wingtip shapes on performance, and the ideal gap between the wings of a biplane.
The Wrights recognized that the "well-digging" problem was the result of adverse yaw, an increase in drag that caused a positively warped wing to "fall behind," as they put it, rather than rise. They reasoned that a fixed vertical rudder at the rear of the craft would counteract the adverse yaw and keep the aircraft moving straight ahead. Once in camp, however, they recognized that the rudder would be even more effective if linked to the wing warping system, so as to automatically turn in the appropriate direction. The final rudder configuration -- twin vanes linked to move with the wing-warping system -- was installed on the glider for the 1903 season.
The Wrights completed 700 to 1,000 glides with the new machine during the 1902 season (September 19 to October 24). They made an additional 175 to 235 flights between September 28 and November 7, 1903, while they were assembling and testing the first powered airplane. The record distance for both seasons was something in excess of 610 feet. Their best time in the air, achieved on October 26, 1903, was 1 minute, 11.8 seconds.