Flight of 1902 Wright Glider
The 1902 Wright Glider was the third free-flight glider built by the brothers.
This was their first glider to incorporate yaw control by use of a rear rudder, and its design led directly to the powered 1903 Wright Flyer.
The brothers designed the 1902 glider during the winter of 1901-1902. The wing design was based on data from extensive tests of miniature airfoils in their homemade wind tunnel. They built the components of the glider in Dayton and completed assembly at their Kill Devil Hills camp in September 1902. Testing began on September 19. The new rear rudder improved turning control, but several times the pilot was unable to stop turning and collided with the ground. The brothers decided to make the rear rudder steerable to solve the problem. With this modification, they achieved true control and made between 700 and 1000 glides (as estimated by the brothers, who did not keep detailed records). The longest glide was measured and timed at 622.5 ft (189.7 m) in 26 seconds.
By December 1901, the Wright brothers had accumulated all the aerodynamic data they needed to build a successful flying machine. However, they did not immediately try to build a powered airplane. They could not be sure that data obtained from tiny model wings would translate to a full-size aircraft. And they still had to solve the mysterious control problems that surfaced during the 1901 glider trials.
Rather than risk life and limb on a large, heavy, untried powered flying machine, Wilbur and Orville decided to build one more glider.
As always, the Wrights first flew their new glider as a kite. Its vastly improved lift performance was immediately evident, and it could sustain nearly level flight. Compare these photos of the three different gliders. The 1902 glider has a low angle of attack and nearly vertical kite lines, indications of a better ratio of lift to drag.
After the kiting tests, Wilbur and Orville began to fly the aircraft as a glider. The new fixed vertical rudder seemed to cure the control reversal problem they experienced in 1901—at least most of the time. Sometimes the reversal of the turn was even more sudden and violent. The Wrights called these episodes “well digging,” referring to the small crater left in the sand when the glider uncontrollably hit the ground.
To solve the control reversal problem, the Wrights made the rudder movable, so its position could be coordinated with the wing-warping. They connected the rudder control cables to the wing-warping hip cradle, so a single motion by the pilot operated both controls. They also changed the original double rudder to a single rudder.
After modifying the glider’s rudder, the Wrights now had a true three-dimensional system of control. This three-axis control system was their single most important design breakthrough, and was the central aspect of the flying machine patent they later obtained. In its final form, the 1902 Wright glider was the world’s first fully controllable aircraft.
The third in a series of gliders leading up to their powered airplane, the 1902 glider was the Wright brothers’ most advanced yet. Reflecting their single, evolving design, it was again a biplane with a canard (forward) surface for pitch control and wing-warping for lateral control. But its longer, narrower wings, elliptical elevator, and vertical tail gave it a much more graceful, elegant appearance.
Like the 1901 glider, this one also had a spruce framework supported within pockets sewn into its muslin fabric covering. The fabric was again applied on the bias (the direction of the weave at a 45-degree angle). The wings were rigged with a slight downward droop to counteract side-slipping due to crosswinds.