Реферат по предмету "Иностранный язык"


Orville And Wilbur Wright Essay Research Paper

Although the 1902 flyer was the first truly-effective heavier-than-air craft, it didn’t have a propulsion system, and so counts only as a glider, not as an airplane. The problem for the Wrights in 1903 was to develop a powered machine.

They had to make one more breakthrough to be successful here: understand how propellers work. This was harder than it seems, as no one really understood that a propeller was nothing more than a wing that rotates on its axis, and lifts the plane forward. So, the Wrights turned to the ship-building literature and discovered that empirical principles were used, but there was no theory of propulsion. They then reasoned out the basic mental model of the propeller as a moveable wing. This allowed them to test propeller shapes in their wind tunnel, discovering an efficient shape. For their 1903 plane, they needed all the efficiency they could get.

To drive a propeller, you need a powerplant. The Wrights wanted a lightweight gasoline engine that would provide the necessary oomph. They tried to buy an engine, but no one was willing to build one to their specs. So, with the able assistance of Charles Taylor, they built their own. It was a state-of-the-art four-cylinder model. Taylor hand-tooled the crankshaft on the Wright shop lathe. Its power-to-weight ratio was better than anything around. Even still, in the words of Charles Taylor, “It weren’t much of an engine.” There was no carburator. The raw gas was just dumped into the cylinders. It was air-cooled, without even the benefit of fins. To control the engine speed, the spark could be advanced or retarded. It had the horsepower — barely — to drag the 1903 machine into the dense December ocean air. As the engine broke in the next year, it began to produce more horsepower, and better flights.

Click here for access to pictures from 1903 (from the mother web site)

On Monday, December 14, 1903, when both the Wright flyer and the wind were ready, the brothers decided that Wilbur would take the first turn as pilot. Some readers might suppose that this was because Wilbur was older, or because he had taken the early lead in the project (though later there was an equalization), or perhaps because of some difference in piloting skills. It was none of these. It was decided by flipping a coin. They and the ground crew (5 lifeguards from the beach) had lugged the plane weighing six hundred pounds 1/4 mile to the big hill, laid out the 60-foot monorail, and were ready to go. After an initial problem getting it unhooked because of the slope (and the force from the propellers), the plane accelerated down the track so fast that Orville, running alongside to steady the wing by holding on to an upright, couldn’t keep up. Wilbur turned the sensitive rudder up too sharply, the flying machine nosed up, slowed, came down in that position, and the left wing hit the sandy hillside and swung the plane around, breaking several parts. Although they didn’t consider this a real flight, they now knew it would work.

Two days later, repairs had been completed, but the wind wasn’t right. The following day, Thursday, December 17, 1903, would be the historic day. They realized it would be better to lay the track on flat ground. That and the strong (22-27 m.p.h.) winds meant that Orville (whose turn it was to pilot) was riding the plane along the track, at a speed that allowed Wilbur to keep up easily, steadying the right wing as Orville had done 3 days earlier. Just after the Wright flyer lifted off the monorail, the famous picture was taken, possibly the most reproduced photograph ever, which Orville had set up (having asked one of the men simply to squeeze the shutter bulb after takeoff). The flight wasn’t much–12 seconds, 120 feet. But it was the first controlled, sustained flight in a heavier-than-air craft, one of the great moments of the century.

The brothers flew 3 more times that day, covering more distance as they got used to the way the large front rudder responded in flight. Orville’s second flight was 200 feet, and Wilbur’s before it nearly as long. But the final flight of the day carried Wilbur 852 feet in 59 seconds.




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