The engine and the propellers were installed in an aircraft that had the same configuration as the 1902 glider but was larger, more rugged and improved in construction. Anyone examining the aircraft or the engineering drawings must be impressed by the Wrights' mastery of techniques based on wood, wire and fabric. The Flyer had a wingspan of 40 feet, a chord of 6.5 feet and a total area of 510 square feet. The weight with a pilot was 750 pounds, giving a wing loading of 1.5 pounds per square foot.

Wilbur and Orville arrived at Kill Devil Hills on September 25, 1903, this time for their longest stay, namely three months. They rebuilt their 1902 building and constructed a new one (44 by 16 feet) for the Flyer. When the weather was favorable, they sharpened their flying skills with the 1902 glider. They spent the rest of the time assembling the new airplane and carrying out preliminary tests of it.

In October the brothers learned of Langley's first unsuccessful test. The news may have been encouraging, but their own chance of success was marginal and they knew it. Their airplane was 25 pounds heavier than they had expected. The machine had not been assembled before the trip to Kitty Hawk, so that the engine and the propellers had not yet been operated on it. In the first test the engine ran roughly, and then two propeller-shaft attachments failed. They were sent to Dayton for repairs on November 5.

Until the shafts were returned on November 20 the brothers could do little. Time was running short, inasmuch as the Wrights knew Langley was preparing for another test. Weather conditions were becoming a problem, with the temperature occasionally dropping below freezing at night, but by November 23 enough tests had been run to measure the total thrust: 132 pounds. Because the brothers had estimated the drag to be 95 pounds they were now confident their machine would take off and fly.

While the engine was being run to test instruments on November 28 a propeller shaft cracked. It had to be replaced, and so Orville returned to Ohio to make two new shafts of stronger material. On the train leaving Dayton for the trip back to Kitty Hawk he read newspaper accounts reporting that Langley's flying machine had been destroyed on launching the day before, December 8. The competition was out of the race.

With all repairs finished the Flyer was prepared for tests on December 14. Wilbur won a coin toss and became the pilot for the first flight. The launching rail was laid on a slight incline so that gravity would aid the launching into a weak breeze. In a slight crosswind the aircraft took off but soon stalled, striking the ground 60 feet from the end of the rail. The forward control surfaces and their supporting structure were damaged but were easily repaired.

FORCES ON A GLIDER WING include the weight (W), the lift and the drag. In the procedure employed in about 1900 to design a wing surface the glider was assumed to be flying steadily (here toward the left) at a velocity (V) along a path making the angle fl below the horizon. A small portion of the weight (W sin O) acts to pull the glider forward, just balancing the drag. The lift was defined as being perpendicular to the flight path, supporting the other component (W cos O) of the weight. The lift and the drag are functions of the angle of incidence (a).

DATA ON LIFT obtained by Lilienthal in 1889 (darker) and by the Wrights in 1901 (lighter) are compared. The Wrights had to contend with the fact that their first intensive flight tests, which they made with their 1900 glider, showed that their Wings were generating less lift than Lilienthal's data had led them to expect. Their first solution for correcting the situation was to increase the camber of their wings; they then carried out wind-tunnel tests. They eventually discovered that their results were quite close to Lilienthal's when the angle of incidence of the wing was between five and 10 degrees and that the source of the error lay elsewhere.

WRIGHTS' PROPELLER DESIGN, which they worked out themselves after finding that the published data on marine propellers offered lime useful information, was based on the principle that a small segment of the blade could be treated as a wing section. The marine data suggested that the most efficiency for a given amount of power would be obtained by passing the largest possible amount of air through the propeller. This concept accounted for the rather large diameter (8.5 feet) of the two propellers on the Wrights' Flyer of 1903

Orville was pilot for the second test, which took place on December 17. The wind was steady at 27 miles per hour, which was a dangerously large fraction of the Flyer's cruising speed of from 30 to 35 m.p.h. Wilbur guided the starboard wing during the launching, with the rail now positioned on a level stretch of sand, and Orville took off. His flight covered 120 feet at an average ground speed of 7 m.p.h. This successful flight is the subject of one of aviation's most moving and best- known photographs, which shows the plane flying a few feet off the ground with Wilbur running alongside.

Each brother made two flights that day before the Flyer was blown across the sand and damaged beyond easy repair. After logging a total of 98 seconds in the air the first powered, man-carrying airplane never flew again. It is now .

For two more years the Wright brothers worked alone to perfect their new airplane. Their progress was not generally known. In the aeronautics community only Chanute was not skeptical of their claim to have the first truly successful flying machine. In 1906 the Wrights were granted a U.S. patent for their system of lateral control, involving both deflection of the wing surfaces and movement of the vertical tail.

Only after they had completed satisfactory licensing agreements in the U.S. and Europe were the brothers willing to show their airplane (an improved version of the 1903 Flyer) in public. Wilbur first flew publicly near Le Mans in France in August, 1908; a few days later Orville gave a demonstration at Fort Myer, Va. The flying skills of the brothers startled the world, and the Wrights became internationally celebrated.

Their airplanes of 1908 had the same basic configuration as the 1903 Flyer, but the design could not survive. Within less than two years aircraft with aft tails showed superior performance, and the Wrights were forced to abandon the canard. They contributed little thereafter to the development of aircraft, but their achievements in the period from 1899 to 1908 remain unparalleled.

FIRST FLIGHT of the 1903 Flyer was photographed at Kill Devil Hills near Kitty Hawk by John T. Daniels of the Kill Devil Life Saving Station, who was using the Wrights' camera. The date was December 17,1903. Orville is the pilot and Wilbur is running alongside. The flight, which was one of four flights made by the Wrights that day, covered 120 feet at an average speed of seven miles per hour over the ground. Wilbur made the last and longest flight of the day, staying aloft for 59 seconds. After a total flight time of 98 seconds that day the Flyer was never taken into the air again. It is now on display at the Air and Space Museum of the Smithsonian Institution.

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