On a December day in 1903, the Wrights changed the world with a 12-second flight.
After the success of their 1902 Glider, the Wright Brothers realized that they now had a suitable wing design and an effective flight control system. All they still needed for powered flight was a means to produce forward thrust, and this consisted of two components: a propeller and an engine. And so they began planning for an engine-driven version of their Glider, which they referred to as “The Flyer”.
When Wilbur and Orville first began to think about a propeller for their powered flyer, they assumed, as had all the other aeronauts before them, that in theory an aircraft propeller was much the same thing as a marine propeller, and that it worked by pushing itself against the air in the same way that a ship’s “screw” pushed against the water. In reality, though, despite several attempts by people around the world, no one could get this concept to actually work.
It was now that the Wrights once again demonstrated their genius. Looking at the data which they had gathered from their wind tunnel experiments, they realized that everyone else had been approaching the problem in a way that was completely wrong: an aerial propeller was not, they realized, an analogue of a ship’s propeller, but was instead an aerodynamic wing that sat on its side and turned in the air to produce “lift” at its front surface—thrust—which pulled the aircraft forward in the same manner that the lift on a wing pulled it upward.
Once that remarkable insight was grasped, the rest fell into place. Looking again at their wind tunnel data, they selected a curved shape labeled “Number Nine” which seemed to produce the best results, and based their propeller blade on it. However, they realized that a propeller, unlike a fixed wing, turned through the air in a constant spiral, and that some modifications needed to be made in its shape to account for that. Using some complicated math, they figured out what the best theoretical curved and slightly twisted shape would be, then hand-carved a series of wooden models to those measurements and tested them using a gasoline engine in the shop. To their relief, the measured thrust came within 1% of their mathematically-calculated values. The final propeller shape they settled on, carved from several layers of spruce glued together, had a measured efficiency of at least 75%–that is, it converted about three-fourths of all the energy from the engine into thrust. This achievement, made with paper, pencil, and hand tools, is all the more amazing when one considers that even the best computer-designed wooden propellers made today have a top efficiency of around 85%.
After some more calculations and testing, the brothers decided that the best configuration for a flying machine would use two slowly-turning propellers, which gave better thrust than would one larger rapidly-turning set of blades. To avoid creating air turbulence over the wings, which would interfere with lift, the two propellers would be mounted at the back of the plane, in what is today known as a “pusher” design. The Wrights also understood that the spinning propellers would create a gyroscope effect that would tend to rotate the relatively lightweight aircraft in the direction opposite to that of the turning blades, and this would interfere with aerodynamic control in flight: to counteract this, they mounted the drive chains (made from bicycle parts) so that each propeller turned in the opposite direction to counterbalance the torque produced by the other. It is the same counter-rotating principle used in modern multi-engine airplanes.
The amazingly efficient propeller design also allowed Orville and Wilbur to solve another problem that had defeated every other potential flyer—the engine. With their non-aerodynamic paddle-shaped propellers, all the other aeronauts were forced to try to make up for that inherent inefficiency through sheer brute power, using high-horsepower engines that were, of necessity, big and heavy. It was an impossible task, which is why none of them ever got off the ground. But the Wrights, with their unique thrust-producing propeller design, could get by with a much smaller engine. It was a breakthrough of immense significance.
But it was still no easy task. After many calculations and tests, the brothers concluded that they needed an engine of at least 8 horsepower to generate sufficient thrust in the propellers to keep the flyer airborne, and that it could not weigh more than 200 pounds. No such engine existed at that time—even the smallest and lightest gasoline-powered automobile engines were far too heavy. So, once again, the Wrights went off in their own direction, and decided that if no such engine existed, they would design and build it themselves.
Recruiting a mechanic from their bicycle shop named Charlie Taylor, the brothers went to work. Their first innovation came after they learned of two automobile makers in Europe—named Benz and Daimler—who were successfully making automobile engines out of a new material, aluminum. This had the advantage of being much lighter than steel, although it was also much more expensive. After making several different test versions, Taylor and the Wrights began casting their engine blocks from an alloy of 92% aluminum and 8% copper, which gave the best balance of strength, weight, and heat resistance.
The first of the Wright engines was powered up in February 1903. The next day, during a bench test, it overheated and seized up, destroying itself. Improvements were made and new tests carried out, and by July a workable and reliable engine was ready.
The engine was unsophisticated, even by 1903 standards. There were four cylinders, in a horizontal straight-line configuration. The fuel tank held just 22 ounces and was mounted on one of the wing struts, where the gasoline was gravity-fed into the engine. There was no throttle—once turned on, the engine ran at full speed. There was also no battery—the engine was started by priming each cylinder with a bit of gasoline, opening the switch on a pack of dry cells on the ground, and igniting the gasoline by manually turning both props. A magneto then took over. The ignition sparks came from two contacts inside the cylinders. And there was no radiator: instead, water from a small tank mounted on the wing drained into a jacket around the engine block to keep it cool.
But the finished powerplant weighed just 180 pounds and produced 12 horsepower. It would, the Wrights calculated, be more than enough to get them into the air.
The control system on the Flyer was essentially the same as the 1902 Glider. As in the Glider, the wing-warping and rudder systems were both connected by cables to a wooden cradle at the pilot’s hips, which he operated by moving his body from side to side. The elevators at the front of the Flyer were operated by a small wooden lever. Since the sandy soil at Kitty Hawk was unsuited for wheels, the brothers planned to launch the Flyer from a 60-foot long steel-topped wooden rail that would be half-buried in the ground. Once the engine started, the plane was held back by a rope connected to a metal clip near the pilot, which was then released for takeoff.
By September 1903, the Wrights were ready to put their Flyer to the test, and transported themselves and the crated machine to Kitty Hawk NC. After some test flights in their 1902 Glider to re-familiarize themselves with the controls, they assembled the Flyer, fixed a few minor problems with the transmission chains, and prepared for their first flight. Supremely confident in their calculations, they had already cabled their father back in Ohio that “Success is certain”.
The first attempt was made on December 14, when the two brothers tossed a coin to see who would go first. Wilbur won, and climbed into the control cradle. But as he rolled down the takeoff rail something went wrong and the Flyer tumbled off, causing some minor damage to the frame.
Three days later on December 17 they were ready to try again, and this time it was Orville’s turn. At 10:35am, he lifted off into the air and traveled 120 feet in the next 12 seconds. The distance he covered was less than the wingspan of a modern passenger jet, but it changed the world.
For the rest of the day, the two brothers took turns piloting the Flyer. Their second and third flights each covered around 200 feet, and the fourth flight, with Wilbur as pilot, lasted an incredible 59 seconds and covered 852 feet.
By this time, the winds had begun to pick up, and as Orville and Wilbur discussed whether they should try a fifth flight, a sudden gust blew the flimsy little Flyer onto its back, breaking the wings and cracking the aluminum engine block. The world’s first airplane would never fly again. The Wrights packed it into a crate and returned to Ohio.
Still crated, the Flyer was stored behind a shed at the Wright Bicycle Shop, and left there for the next 13 years. At one point it was covered with water and mud for almost two weeks during a flood. In 1916 the Flyer was re-assembled with a new engine and exhibited at various places over the next several years.
In 1925 Orville Wright (Wilbur had died in 1912) found himself in a controversy with the Smithsonian Institution. When the Smithsonian exhibited Langley’s Aerodrome as the first airplane “capable of flight”, Orville took offense, and instead of donating the historic 1903 Flyer to the Smithsonian, he sent it on loan to the London Science Museum in 1928. It remained there until 1948 when, after the Smithsonian formally apologized and acknowledged that the Wrights had been first, the aircraft was shipped back to DC. It was displayed in the Smithsonian Arts and Industries Building until 1975, when the new Air and Space Museum opened. In 1985 the Flyer underwent a restoration, and in 2003 it was relocated to its own gallery in the museum titled “The Wright Brothers and the Invention of the Aerial Age”.