- Historic Sites
The First To Fly
June 1970 | Volume 21, Issue 4
But it didn’t. The first time the brothers tried it out on the big dune at Kill Devil Hills it nosed into the sand after going only a few yards. A second test flight yielded the same results. Believing that there was too much weight forward, the Wrights tried shifting the position of the pilot farther aft for their third attempt. “The machine then sailed off and made an undulating flight of a little more than 300 feet,” Wilbur noted. “To the onlookers, this flight seemed very successful, but to the operator it was known that the full power of the rudder had been required to keep the machine from either running into the ground or rising so high as to lose all headway. In the 1900 machine one fourth as much rudder action had been sufficient to give much better control. It was apparent that something was radically wrong, though we were for some time unable to locate the trouble.”
The brothers resumed experiments with the machine tethered as a kite in winds of approximately seventeen miles per hour. Even though they had meticulously designed the wings to correspond with the design used by Lilienthal when he worked out his tables, they found that the lifting power was far less than it should have been. They reasoned that the curvature, or camber, of their wings was too great, despite the fact that it was exactly what Lilienthal recommended. But the Wrights figured that if the top surface of a wing was curved too much, the air flow over the top surface would strike the forward, or leading, edge of the wing at such an angle as to force it down.
So they changed the shape of the wings on their glider and flattened out the curvature of the top surface.
“On resuming our gliding, we found that the old conditions of the previous year had returned; and after a few trials, made a glide of 389 feet. The machine with its new curvature never failed to respond promptly to even small movements of the rudder. … And thereafter we made glide after glide, sometimes following the ground closely, and sometimes sailing high in the air.”
The weather turned rainy and unpleasant as the end of August approached, and camp was abandoned; but their experience with the 1901 glider’s poor performance in its first few flights made them thoroughly skeptical of the data developed by Lilienthal, and they returned to Dayton determined to run some tests and find out for themselves what kind of wing produced the greatest lift. After experimenting with various testing devices, they finally built a wind tunnel in their Dayton workshop. It was small, measuring six feet in length and having a cross section of sixteen inches square. At one end, a two-bladed fan, driven by a gasoline engine used in their bicycle shop to power a lathe, drill press, and band saw, developed a wind of twenty-five to thirty-five miles per hour. This blast passed through a honeycomb which straightened out the air current generated by the whirling blades of the fan. The wing section to be tested was mounted in the other end of the wind tunnel so that it could move back and forth in the air stream, the amount of movement indicating the amount of lift a particular shape developed. A direct reading of the amount of drag, or resistance to the air flow, was also possible.
The Wright wind tunnel was not the first ever used to test wing shapes, but none had achieved results so spectacular. In their work with their homemade wind tunnel, these two untrained, self-educated engineers demonstrated a gift for pure scientific research that made the more eminent scientists who had studied the problems of flight look almost like bumbling amateurs.
By early October, 1901, the Wrights had their wind tunnel set up and operating well. In the next month they tried out more than one hundred miniature wings of various shapes, including models of bird wings. The letters between Wilbur and Octave Chanute flew thick and fast as Wilbur went into detail on the experiments, ancl the older man, somewhat doubtful at first, was gradually won over to the Wrights’ conviction that previous research on wing design was misleading.
“I am now absolutely certain that Lilienthal’s table is very seriously in error, but that the error is not so great as I had previously estimated,” Wilbur wrote to Chanute on October 6.
The Wrights emerged from this series of experiments with several notebooks full of data, mankind’s first good grasp of the complex theoretical formulas required to predict the lifting power and behavior of different types of wings, and a clear idea of which wing designs would work and which ones were useless. As their busy bicycle-manufacturing season wore on, they completed their plans for an improved glider for the next trip to Kitty Hawk.