The Wright Brothers & Aviation History

Here is an introduction to the Wright brothers' contributions to aviation history. For a timeline of aviation progress before the Wright brothers, click to this timeline.

Included below:

• Wilbur and Orville Wright
• The Basic Problems of Flight
• How the Wrights Solved the Problems of Flight
• The Wright Brothers and Aviation after 1903

Wilbur and Orville Wright

Wilbur Wright was born April 16, 1867 in Millville, Indiana. Orville Wright was born August 19, 1871 in Dayton, Ohio. Together these brothers operated The Wright Cycle Company, a small bicycle shop, in Dayton.

Wilbur was quiet and intense. He was a dreamer who could lose himself in books. Orville was outgoing, talkative, and an immaculate dresser. They both combined intuitive mechanical ability with analytical intelligence.

The brothers' bicycle shop was prosperous, but they were restless. Their energies were focused by two events of 1896; the death in a flying accident of Otto Lilienthal, the celebrated experimenter with gliders, and the successful launching of powered models by Samuel Langley, whose early successes attracted financial support from the War Department.

The Basic Problems of Flight

Any aircraft design has to solve three critical problems:

1. Lift: generating an upward force greater than the weight of the plane.
2. Thrust: propelling the plane forward.
3. Control: stabilizing and directing the plane's flight.

Here is more information about each one.

Lift

Air passing over the arched, or cambered upper surface of a wing must travel farther than the air passing beneath the wing. It thus has to move faster, making the air pressure drop relative to the pressure under the wing. Upward lift is created. The degree of curvature of the upper surface and the ratio of the wing span to its chord (distance from the front to the back of the wing) affect lift.

The angle of attack -- the angle at which the wing meets the air -- also affects lift. The greater the angle, the greater the lift, up to a point. Past a certain angle, the smooth flow of the air over the wing suddenly becomes turbulent and "stalling" occurs. That is, lift is lost. At higher speeds, less angle is needed to generate the same amount of lift.



Control

A wing is inherently unstable fore-and-aft. This is because lift is greatest behind the center of gravity making the wing rotate around that point. The nose pitches down, the tail comes up. To counteract this, the horizontal stabilizer acts as an inverted wing, creating negative lift to hold the tail down. Lateral stability of the plane is affected by the amount of dihedral; the deflection from horizontal built into the wings. Movable control surfaces produce the three movements needed for maintaining control of the aircraft and changing direction.

The elevator produces pitch (up-down movement of the nose), for longitudinal control. Ailerons produce roll (rotation of the wings), for lateral control. The rudder produces yaw (right and left movement), for directional control. These movements in combination turn the aircraft.

Thrust

Just as air flow over the wings generates lift, air flow over the rapidly turning blades of a propeller-driven plane produces thrust, or forward motion. Each blade of the propeller acts as a small airfoil, or wing. As the blade rotates, air flows over its curved surface. The resulting horizontal "lift" propels the aircraft forward. Because the velocity of the blade increases from hub to tip, the blade is twisted, providing the most efficient angle of attached at each point along its length.

How the Wrights Solved the Problems of Flight

The Wright's serious work in aeronautics began in 1899 when Wilbur wrote the Smithsonian for literature. Dismayed that so many great minds had made so little progress, the brothers were also exhilarated by the realization that they had as much chance as anyone of succeeding.

The Wrights knew that the solutions to lift and propulsion needed only refining, but no one had achieved lateral control. Rejecting the principle of inherent stability -- the conventional wisdom -- they wanted control to depend on the pilot. Wilbur hit upon the idea of warping the wings -- sparked by his observation of birds and the idle twisting of a box -- to rotate the wings and stabilize flight. In 1899, they tested wing-warping -- the forerunner of ailerons -- on a 5-foot biplane kite.

Confident their design was sound, in 1900 the Wrights built a 17-foot glider with an unusual forward elevator. They went to Kitty Hawk hoping to gain flying experience, but the wings generated less lift than expected, and they flew the glider mostly as a kite, working the control surfaces from the ground. Wilbur's time aloft in free flight totaled only 10 seconds. They went home somewhat discouraged, but convinced they had achieved lateral and longitudinal control.

In 1901, the Wrights sharpened their focus. Trying to overcome the lift problem, they increased the camber of the glider. They also lengthened its wingspan to 22 feet, making it the largest glider anyone had attempted to fly.

But on the remote, sandy beach at their new Kill Devil Hills camp in Kitty Hawk, lift was still only a third of that predicted by the Lilienthal data upon which the wing design was based. And the glider pitched wildly, climbing into stalls.

When they returned to the earlier camber, they achieved longitudinal control and eventually glided 335 feet. But the machine was still unpredictable. When the pilot raised the left wing to initiate the expected right turn, the machine instead tended to slip to the left (adverse yaw). This failure, and the realization that their work had relied on false data, brought them to the point of quitting. Instead they built a wind tunnel and produced their own data.

The Wrights' 1902 machine embodies their new research. They gave it efficient 32-foot wings and added vertical tails to counteract adverse yaw. The pilot moved a hip cradle to warp the wings.

Some 400 glides proved their new design to be workable, but still flawed. Sometimes, when the pilot tried to raise the lowered wing to come out of a turn, the machine instead slid sideways toward the wing and spun into the ground. Orville suggested a movable tail to counteract this tendency. After Wilbur thought to link the tail movement to the warping mechanism, the plane could be turned and stabilized smoothly. If others had thought about steering at all, it was by rudder -- a marine analogy unworkable in the air. The Wrights saw that control and stability were related, that a plane turned by rolling.

Six hundred more glides in 1902 satisfied them that they had the first working airplane.

Now the Wrights had to power their aircraft. Gasoline engine technology had recently advanced to where its use in airplanes was feasible. Unable to find a suitable lightweight commercial engine, in 1903 the brothers designed their own. It was cruder and less powerful than Samuel Langley's, but the Wrights understood that relatively little power was needed with efficient lifting surfaces and propellers. Such propellers were not available, however, scant relevant data could be derived from marine propeller theory. Using their air tunnel data they designed the first effective airplane propeller, own of their most original and purely scientific achievements.

Returning to the Kill Devil Hills, they mounted the engine on the new 40-foot, 605-pound Flyer with double tails and elevators. The engine drove two pusher propellers with chains, one crossed to make the props rotate in opposite directions to counteract a twisting tendency in flight. A balky engine and broken propeller shaft slowed them, until they were finally ready on December 14.

Wilbur won the coin toss, but lost his chance to be the first to fly when he oversteered with the elevator after leaving the launching rail. The flyer climbed too sleepy, stalled, and dove into the sand. The first flight would have to wait on repairs.

Three days later, on December 17, 1903, they were ready for the second attempt. The brothers were dressed in coats and ties that December morning -- a touch of private ceremony for an event that would alter the world.

The 27-mph wind was harder than they would have liked, since their predicted cruising speed was only 30-35 mph. The headwind would slow their groundspeed to a crawl, but they proceeded anyway. The pools around their camp were icing up, and this might be their last chance of the season.

With a sheet, they signaled the volunteers from the nearby lifesaving station that they were about to try again. Words were impossible over the engine's roar, so they shook hands and Orville positioned himself on the flyer.

Remembering Wilbur's experience, he carefully tested the controls. The stick that moved the horizontal elevator controlled climb and descent. The cradle that he swung with his hips warped with wings and swung the vertical tails, which in combination turned the machine. A lever controlled the gas flow and airspeed recorder. The controls were simple and few, but Orville knew it would take all his finesse to handle the new and heavier aircraft.

At 10:35 he released the restraining wire. The flyer moved down the rail as Wilbur steadied the wings.

Just as Orville left the ground, John Daniels from the lifesaving station snapped the shutter on a preset camera, capturing the historic image of the airborne aircraft with Wilbur running alongside.

Again, the flyer was unruly, pitching up and down as Orville overcompensated with the controls. But he kept it aloft for 12 seconds until it hit the sand about 121 feet from the rail. Into the 27-mph wind the groundspeed had been 6.8 mph, for a total airspeed of 34 mph.

For the first time, a manned, heavier-than-air machine left the ground by its own power, moved forward under control without losing speed, and landed on a point as high as that from which it started.

The brothers took turns flying three more times that day, getting a feel for the controls and increasing their distance with each flight. Wilbur's second flight -- the fourth and last of the day -- was impressive 852 feet in 59 seconds.

The Wright Brothers and Aviation after 1903

"They have done it!" Damned if they ain't flew!" said a witness to the Wrights' achievement in December 1903. But so often had this claim proven hollow that the public was skeptical of yet another, especially after the spectacular failure of Langley's flying machine 9 days earlier.

Undismayed, the Wrights built an improved flyer and refined their flying skills over a field in Ohio, making 105 flights in 1904.

In their 1905 flyer, 38 minutes became routine. But when the Wrights offered the flyer to the U.S. Army, that institution, dubious of their achievement, refused to meet with them. Unwilling to show their control system without a contract in hand, the Wrights did not fly for another three years.

Despite the break in their progress, the gap between the Wrights and European aviators remained substantial. After 1903, the French built flyers based on the Wright gliders. But by 1906, none had remained aloft for more than a few seconds of ragged flight. Not until 1907 did a European plane stay in the air as long as the Wrights had in 1903. But the Wrights' refusal to fly caused even early believers to doubt their success.

The Wrights finally signed a contact with the U.S. Army in 1908 and showed the world what they could do -- Wilbur in France, Orville in America. After Wilbur flew a circle under good lateral control and landed gently, no one questioned that the Wrights had truly mastered flight.

The French attempts were still shaky, on the edge of control. What Wilbur had done was effortless, graceful, decisive. In other flights he flew over two hours and reached an altitude of 360 feet, demonstrating the flyer's reliability and endurance. "We are as children compared with the Wrights," said one French pilot.

By 1910 the rest of the world had caught up. The French rapidly introduced refinements to the Wright design; monoplane wings, closed body, front propeller, rear elevator, single stick control, wheels, and ailerons. But the principle being the Wright's control system was unchanged.

The Wrights' 1911 model reflected the French refinements. It is the prototype for every plane in the air today.

Within two generations of the Wrights' achievements, we have taken to the air for routine travel, seen an aircraft break the sound barrier, and watched a man walk on the moon.

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