In 2003, the world will celebrate the 100th anniversary of the first flight of an airplane by the Wright brothers. While much attention will be paid to the events of December 17,1903, at Kitty Hawk, North Carolina, it is important to note that the four flights of that day were only one small step in the development of the airplane. On this page, we show scaled computer drawings of the six aircraft which the brothers designed and built leading up to the first practical airplane.

The process which lead to the first successful airplane is the same process used by engineers today to solve problems. The brothers from Dayton, Ohio, began with an interest in flying things. Their father had brought them a flying toy "bat" powered by a rubber band in the 1870's. As teens in the 1880's, they built and flew kites. In the 1890's, they read about the hang-gliding flights of Otto Lilienthal and his death in an air crash. They recognized that control of a flying aircraft would be the most crucial and hardest problem to solve. And they had an idea about how to solve that problem. They first performed a literature search to find out the state of aeronautical knowledge at their time by reading about the works of Cayley, Langley and Lilienthal. They corresponded with Octave Chanute concerning some of their ideas. From the observation of soaring birds, they believed that they could obtain roll control by warping, or changing the shape, of a portion of the wing. To test their idea, they built a small kite in 1899 which could be maneuvered by pulling on two control lines.

Between 1900 and 1902 they built a series of large unpowered aircraft to develop and refine their ideas of flight. These aircraft were repeatedly flown as piloted gliders and as unpiloted kites. Each aircraft was designed and built in Dayton, but they were flown at Kitty Hawk where higher and more consistent winds were to be found.

The 1900 aircraft was the first plane flown by the brothers. It demonstrated that roll control could be provided through wing warping. On this aircraft, pitch control was provided by an elevator, called a canard, which was placed at the front of the aircraft. The location was probably chosen for safety reasons; to provide some structure between the pilot and the ground in a crash. There is also a small aerodynamic lift advantage in placing the elevator at the front unlike modern airplanes where the elevator is placed at the rear. Even with the increased the lift, the aircraft did not perform as well as the brothers predicted using available data.

The 1901 aircraft had the same basic design as the 1900 aircraft, but was larger to provide more lift to carry a pilot in lighter winds. The aircraft was flown frequently up to 300 feet in a single glide. But the aircraft did not perform as well as the brothers had originally expected. The aircraft only developed 1/3 of the lift which was predicted by the Lilienthal data. The brothers modified the curvature of the wing but this only slightly improved the flying characteristics. During their test flights the brothers first encountered wing stalls in which the lift would suddenly decrease and the aircraft would settle back to earth. They also encountered an effect known as adverse yaw. On some flights, when the wings were warped to produce a roll which should result in a curving flight path in the direction of the lower wing, the drag increased on the upper wing and the aircraft would twist in the opposite direction. The air speed decreased and the plane settled back to the ground. At the end of 1901, the brothers were frustrated and Wilbur remarked that humans would never learn to fly in his lifetime.

During the winter of 1901, the brothers began to question the aerodynamic data on which they were basing their designs. They decided to start over and develop their own data base with which they would design their aircraft. They built a wind tunnel and began to test their own models. They developed an ingenious balance system to compare the performance of different models. They tested over two hundred different wings and airfoil sections in different combinations to improve the performance of their gliders The data they obtained more correctly described the flight characteristics which they observed with their gliders. By early 1902 the Wrights had developed the most accurate and complete set of aerodynamic data in the world.

In 1902, they returned to Kitty Hawk with a new aircraft based on their new data. This aircraft had roughly the same wing area as the 1901, but it had a longer wing span and a shorter chord which reduced the drag. It also sported a new movable rudder at the rear which was installed to overcome the adverse yaw problem. The movable rudder was coordinated with the wing warping to keep the nose of the aircraft pointed into the curved flight path. With this new aircraft, the brothers completed flights of over 650 feet and stayed in the air for nearly 30 seconds. This machine was the first aircraft in the world that had active controls for all three axis; roll, pitch and yaw. By the end of 1902, the brothers had completed over a thousand glides with this aircraft and were the most experienced pilots in the world. They owned all of the records for gliding. All that remained for the first successful airplane was the development of the propulsion system.

Between 1903 and 1905, the brothers built a series of powered aircraft which would eventually lead to the first practical airplane. The Wrights could not find an engine manufacturer who would build a single engine for them. Their glider flight data indicated that they needed about 8 horsepower from a 200 pound engine to power their aircraft. In a period of just six weeks, they built their own gasoline powered, internal combustion engine. They also designed and built highly efficient aircraft propellers, using their wind tunnel results and realizing that they must be shaped as a rotating wing.

In September of 1903, they returned to Kitty Hawk with their new aircraft. The aircraft was similar to the 1902 craft with twin wings, twin rudders, and canard elevators. The plane also carried twin counter-rotating pusher propellers connected by bicycle chains to the 12 horsepower motor. The pilot would lie beside the motor on the lower wing. After a number of frustrating problems with the propeller shafts and transmission sprockets, they finally made four successful flights on December 17, ranging from a little over 100 feet to over 800 feet. Each of the flights was marked by an instability in pitch; the nose, and consequently the entire aircraft, would slowly bounce up and down. On the last flight, hard contact with the ground broke the front elevator support and ended the season's flying.

Returning to Dayton, the brothers began work on the 1904 aircraft. They built a new engine similar to the 1903 engine but with increased horse power by slightly increasing the bore (diameter of the piston). They also built a new airframe which was very similar to the 1903 aircraft but with redesigned rudders. In an effort to solve the pitch problem, the brothers moved the radiator and fuel tank from the front struts to the rear struts and moved the engine aft to move the aircraft center of gravity aft. The new aircraft was flown from a cow pasture owned by Torrence Huffman and located just outside Dayton. Without the winds of Kitty Hawk, it was a problem getting enough airspeed to fly. So the brothers devised a catapult system to help launch the aircraft. Once airborne, the aircraft experienced the same pitch problems as the 1903 aircraft. In fact, moving the center of gravity aft had made the performance worse. So the brothers added 70 pounds of iron bars as ballast to the front canard to move the center of gravity back farther forward. With this improvement and the flying skill of the brothers, the aircraft was able to complete the first circuit of the airfield on September 20, 1904. By the end of the year, the plane could complete four circuits and stay in the air for five minutes, but the aircraft still had major performance problems in pitch and was now carrying additional weight.

The brothers were able to solve this final problem by increasing the size of the elevator and rudder and moving the elevator and rudder farther from the center of gravity on the new 1905 aircraft. This increased the torque produced by the control surface and provided greater control for the aircraft. The radiator and fuel tank were moved back to the front strut and the size of the fuel tank was increased. The engine stayed the same as the 1904 aircraft and the weight was decreased to 860 pounds by eliminating the iron bars. The 1905 aircraft could be flown until the fuel tank was empty; staying in the air for more than a half hour, flying nearly 25 miles around Huffman's farm, executing turns and figure 8's, and flying more than 50 feet off the ground. The brothers now had a practical working airplane and began to market it to the War Department.

You can compare the performance of these six aircraft by using an interactive performance prediction program located on another page. You can also obtain a copy of the graphics for the unpowered and powered aircraft shown at the top of this page. Use your browser's "Back" command to return here.

Responsible Official Tom Benson	Maintained by Dave Mazza	Comments and Suggestions Carol Galica
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