Wright Brothers Aircraft
On December 17,1903, at Kitty Hawk North Carolina, the first piloted, controlled, self-propelled, heavier than air craft, the first airplane, was flown by the Wright brothers. It is important to note that the flights of that day were only the culmination of nearly five years of work by the brothers.
The process which lead to the first successful airplane is the same process used by engineers today to solve problems. The brothers first performed a literature search to find out the state of aeronautical knowledge at their time. They read about the works of Cayley, and Langley, and the hang-gliding flights of Otto Lilienthal. They corresponded with Octave Chanute concerning some of their ideas. They recognized that control of the flying aircraft would be the most crucial and hardest problem to solve. 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.
The First Aircraft
In 1900 they built an aircraft to test their theories. The aircraft had a 17 foot wing span, a five foot chord, and a forward stabilizer, called a canard, and weighed about fifty pounds without the pilot. For most of its flights this aircraft was flown as a kite. Kitty Hawk was chosen as the test site because of its sand dunes and constant strong winds coming in from the sea. On the last day of the season, the aircraft was flown as a piloted glider and demonstrated roll control through wing warping.
In 1901, the brothers returned to Kitty Hawk with a new aircraft which they had built at their bicycle shop in Dayton, Ohio. Their new aircraft had the same basic design as the 1900 aircraft, but was larger to provide more lift to carry a pilot in lighter winds. It had a 22 foot wing span, a seven foot chord, a variable elevator canard for pitch control, and weighed about a hundred pounds without the pilot. 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 drag was greater than predicted and the wing would stall at a lower speed than predicted. The brothers modified the curvature of the wing but this only slightly improved the flying characteristics. During their test flights the brothers 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 it would be years before humans would learn to fly.
Wind Tunnel Testing
During the winter of 1901, the brothers began to question the aerodynamic data on which they were basing their designs. They built their own wind tunnel , the first tunnel built in the United States, and began to test their own models. They tested over two hundred different wings and airfoil sections in different combinations to improve the performance of their gliders They found that the previous data was in error and that their own data more correctly described the flight characteristics which they observed with their gliders.
New and Improved Aircraft
In 1902, they returned to Kitty Hawk with a new aircraft based on their new data. This aircraft was even larger than the 1901 aircraft; it had a 32 foot wing span, a five foot chord, the canard elevator, a new movable rudder at the rear, and it weighed about a hundred and fifteen pounds without the pilot. The rudder 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. This machine was the first aircraft that had active controls for all three axis; roll, pitch and yaw. At the end of 1902, all that remained for the first successful airplane was the development of the propulsion system.
The Wrights could not find a manufacturer who would meet their requirements for both lightweight and horsepower in an engine, so, in a period of just six weeks, they built their own 12 horsepower engine. They also created the first working aircraft propellers, realizing that they must be shaped as a rotating airfoil.
First Powered Aircraft Flight
In September of 1903, they returned to Kitty Hawk with their new powered aircraft. The aircraft was similar to the 1902 craft but with a longer 40 foot wing span, a six foot chord, five feet between the wings and 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 on the motor on the lower wing. With the pilot and the motor, the 1903 aircraft weighed a little over seven hundred pounds. After a number of frustrating problems with the propeller shafts and transmission sprockets, they finally made four successful flights on December 17. These ranged from a little over 100 feet to over 800 feet. After almost 5 years of solving a myriad of problems, Wilbur and Orville Wright had conquered powered flight.