The poor lift performance of their 1900 glider made the Wright brothers question, but not abandon, the aerodynamic data and equations they had relied upon. To increase lift on their next glider, they simply increased the size of the wings and the curvature of the airfoil. They returned to Kitty Hawk in 1901 to test the new glider.
The results were discouraging. Although more and longer free glides were made than in the previous year, the new glider performed worse than the 1900 craft. It still suffered from lack of lift and now had control problems as well.
In keeping with their approach of maintaining continuity of design, the Wrights’ 1901 glider was similar in structural design and layout to their 1900 craft. The wire-braced biplane structure again featured a canard (forward) elevator and wing-warping for lateral control. Rather than the French sateen fabric of the 1900 craft, they used an unbleached muslin called “Pride of the West,” the fabric they would use on the rest of their experimental aircraft.
The Wrights continued with their gradual method of flight-testing. Launched by assistants on either wingtip, their initial glides were just a few inches off the ground. William Tate and his half-brother Dan came by often to help. The testing began to reveal unexpected problems.
Previously smooth and sure, the elevator control was now overly sensitive and erratic. When they warped the wings, the glider initially turned in the intended direction, then suddenly reversed itself. The Wrights were utterly baffled.
The glider produced only one-third the lift that their calculations predicted. The Wrights suspected the large increase they had made in wing curvature (from 1 in 23 to 1 in 12) was causing both the lift and pitch control problems. They re-rigged the wings to a shallower curvature (1 in 19) by altering the tension on the wires running over the vertical wing posts. The responsive pitch control returned, but lift remained poor.
The Wrights left Kitty Hawk discouraged. They had achieved glides of more than 90 meters (300 feet) in the largest glider ever built, but major problems with lift still plagued the aircraft, and new troubles with control appeared. Their goal of a practical airplane seemed more elusive than ever.