Kitabı oku: «Story of the Aeroplane», sayfa 4
In their efforts to construct a practical flying machine they adopted the plan of Lilienthal and Chanute. They sought to construct a machine which they could control and in which they could make glides with safety. This they built in the form of a biplane glider and with it they experimented industriously for years. The successful construction of the machine required a high degree of skill. The length and width of the planes, their distance apart, the materials to be used, the shape, size and position of the rudder and numerous other details were to be worked out only by patient study and frequent tests. They were now in the field of original experiment and soon found that they had to reject as useless many theories that had been carefully elaborated by scholarly writers.
The brothers soon learned that a long narrow plane in a position nearly horizontal, moved in a direction at right angles to one of its lateral edges and inclined or “tipped” slightly upward would develop greater lifting power than a square or circular plane. This discovery was not indeed original with them, but their experiments confirmed the conclusions of their predecessors.
The surface shape of the plane is an important consideration. It has been found that a slight upward arch from beneath, making the under surface concave, gives the best results. The concavity should reach its maximum about one-third of the distance from the front or entering edge to the rear edge of the plane and should be the same whether one or more planes are used. In flight the forward or entering edges of the planes are tipped slightly upward to give the machine lifting power for the same reason that the top of a kite is given an angle of elevation so that the air will lift it as it is drawn forward by the string.
Balancing the Machine
The balancing of a machine in mid-air is one of the most difficult problems in aviation. In the balloon this is easily accomplished because the principal weight, the basket with the passenger, is below the gas-filled sphere or compartment, and the balloon tends to right itself after any disturbance by the wind, much like a plummet when swayed out of its position.
Professor Langley, Lilienthal and others had sought to take advantage of this tendency in the construction of their machines by placing or arching the wings above the pilot or heavier portion of the mechanism. After a slight disturbance in mid-air the machine would then tend to right or balance itself and assume its former position. The practical difficulty of this arrangement, however, arose from the fact that when once set to swaying the gliders thus constructed continued to sway like the pendulum of a clock. The Wright brothers set themselves the task of finding some other method of preventing the biplane from dipping downward or upward at either side with the shifting of air currents. The first device to give steadiness of motion was a small movable horizontal plane, supported parallel with and in front of the two main planes, and by means of a lever, under control of the pilot.
At Kitty Hawk
Having after much study completed their glider, the Wright brothers sought a suitable place for their first tests. By correspondence with the United States Weather Bureau they learned that at Kitty Hawk, North Carolina, the winds are stronger and more constant than at any other point in the United States. This treeless waste of sand dunes along the solitary shore near the village afforded the privacy where they might carry on their work unmolested. Here in October, 1900, they spent their vacation testing their biplane glider. They sought to fly it in the face of the wind like a kite. This they succeeded in doing but it would not support the weight of a man. They then experimented with it, using light ropes from below to work the levers and guide it through the air. It was sufficiently responsive to encourage them and they went back home to make at their leisure a number of improvements.
The year following they returned to the same place with a larger machine considerably improved, but it still failed to lift the operator. Octave Chanute, of Chicago, with whom they had been in correspondence, came to witness their tests and examine their glider. They now decided to abandon much of the “scientific data” which they had collected from the writings of others and proceeded in the light of their own experience. They coasted down the air from the tops of sand dunes and tested with satisfaction their devices for guiding their air craft. In 1902, with additional improvements, they made almost one thousand gliding flights, some of which carried them a little over six hundred feet, more than twice the distance attained the previous year. All this time their object had been to control the machine while in air. Only after this was accomplished did they propose to add motive power to keep it above the earth. They wisely reasoned that it would be useless to apply this power to a machine that could not be directed and controlled.
The First Flight
The Wrights had now reached a point where they felt that they were ready to apply motive power, rise like a bird from the earth and direct their course through the air. A new machine was built with two planes, each six feet six inches wide and measuring forty feet from tip to tip. The planes were arranged one directly above the other with an intervening space of six feet. An elevating rudder of two horizontal planes ten feet in front of the machine, and a rudder of two vertical planes about six feet long and one foot apart in the rear of the machine were under control by levers close to the hands of the pilot, who, prostrate on the lower large plane, directed the course up or down, to the right or left at will. But the most remarkable features of all were the gasoline engine that was to give motive power and the propellers by which that power was to move the machine in its flight through the air. The mechanism, the result of patient study and arduous labor, had been perfected in the little shop at Dayton and had been brought to the barren sand coast of North Carolina for its first practical test. The engine, which developed sixteen horse power, was connected by chains with the two propellers, each eight feet in diameter at the rear of the biplane. The total weight was 750 pounds.
To give the machine a “start” it was driven rapidly along an iron rail by a cable attached to a weight of one ton suspended at the top of a derrick. When everything was at last in readiness, the engine was started, the propellers were set in rapid motion, the weight at the top of the derrick was released, the biplane was driven rapidly forward, and lo! bearing a man, it skimmed over the sand dunes! It continued only eleven seconds but landed without injury to pilot or machine. A small beginning indeed, but it proved the practicability of man flight and ushered in the era of aviation. A few days earlier in the same month on the banks of the Potomac a crowd of witnesses saw with keen disappointment the failure of Professor Langley’s flying machine, and as they turned away said mentally and not a few of them audibly, “Impracticable!” “It can’t be done.” On the sand near Kitty Hawk, in the presence only of the inventors and five others, life savers and fishermen from Kill Devil Hill Station near by, fortune rewarded two brothers unknown to the world and they achieved what had long been regarded as impracticable and impossible. Professor Langley worked long and patiently on his models and was very properly given $50,000 by the government to aid in an enterprise that was to give man dominion of the air. The Wright brothers with the same faith and unflagging zeal worked secretly in their little shop at Dayton without financial assistance and out of their small earnings conducted experiments on the Carolina coast, doing their own cooking to lighten expenses, and solved the problem that had thwarted the inventive genius of the world. No crowds, appreciating the significance of the event were present to applaud, nor did the brothers exult over the achievement. It was indeed only what they had confidently expected.
On the day of their initial success two other nights of slightly longer duration were made. The fourth flight continued fifty-nine seconds, almost a minute, and extended over a distance of 853 feet. The machine was then carried back to camp. In an unguarded moment it was caught by a gust of wind, rolled violently over the ground and was partially wrecked. But what mattered the loss? For the first time in the history of the world a machine carrying a man had raised itself by its own power into the air in free flight, had sailed forward on a level course without reduction of speed and had landed without being wrecked.
