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At the end of this block of study, you should be able to:
5.51 Discuss the contributions to flight made by Leonardo da Vinci.
5.52 Describe the three basic problems of flight.
5.53 List the accomplishments of Sir George Cayley.
5.54 Describe John Stringfellow's work with powered flight.
5.55 Discuss the contributions toward flight made by Otto Lilienthal, Octave Chanute, and Samuel Pierpont Langley.
Flyers face three basic problemsfirst, to develop the lift necessary to rise Into the air; second, to sustain that lift; and third, to control the aircraft once it is flying. Balloonists overcame the first two problems; however, heavier than-air flight pioneers had to struggle with all three problems.
|Leonardo da Vinci|
Leonardo da Vinci (1452~1519), the great Italian artist, architect,
and man of science, made the first scientific experiments In the field of aviation. He
devoted many years of his life to understanding the mysteries of flight, and he left the
world 160 pages of descriptions and sketches of flying machines. Among these
descriptions and pictures are the world's first known designs of the parachute and the
helicopter. From his notes, it appears that he made models of both and may have
flown them successfully. He understood and wrote about the importance of the
center of gravity, center of pressure, and streamlining. These principles are
vital in designing and building modern aircraft and spacecraft. It seems certain that if
he had only concentrated his research in these areas he possibly could have built a
workable manned glider 400 years before the first one was actually built and flown.
However, like so many people before and since, he was obsessed with the idea of man flying
like a bird. He described, sketched, and built models of many types of ornithopters (a
flying machine which is kept aloft and propelled by flapping wings). He left detailed
sketches of wing mechanisms which used levers and pulleys to allow man's muscle power to
flap the artificial wings.
It is important to note that Leonardo da Vinci was a brilliant scientist whose work could have changed the entire history of flight, except for one tragic fact. It was 300 years after his death before his manuscripts were discovered and published.
The first pioneer to enter the area of heavier-than-air flight In the nineteenth century was an Englishman named Sir George Cayley. He was nine years old when the Montgolfiers made their first flight, and he immediately began experimenting with small paper balloons. His interest in flight continued. While a teenager, he built small model helicopters and, like Leonardo da Vinci, studied the flight of birds. In 1804, he constructed a whirling-arm device with which he could test the behavior of air pressure on various types of wings. He later built and flew small model gliders (unpowered aircraft). in 1809, he published the conclusions of his research in a scientific paper. A single sentence in his paper laid the whole foundation for modern aeronautics"The whole problem is confined within these limits, namely to make a surface support a given weight by the application of power to the resistance of air."
During his lifetime, Cayley identified the forces of lift, drag, and thrust as they apply to aviation; developed the cambered (curved) upper surface on a wing to increase lift; worked on engines (power plants) and propellers (to pull or push the craft through the air); developed the concept of two-wing or three-wing (biwing or triwing) aircraft; and built the first successful full-size, manned glider.
The works of Cayley were published and widely read by scientists and aviation enthusiasts throughout the world. Among those who read these documents were two Englishmen who were to make additional contributions to heavier-than-air flight. They were W. S. Henson, an inventor, and John Stringfellow, a skilled engineer. In 1843, they drew up plans and even received a patent for a man-carrying, powered aircraft. This aircraft, named the Ariel, was to be a monoplane with a 15-foot wingspan. It was powered by a steam engine turning two six-bladed propellers. The aircraft was never built, but the plans were masterpieces of aviation engineering. The plans for the wing structure showed a front and rear spar with connecting ribs. This same type structure is used for making aircraft wings today. A small model of the Ariel was built and tested, but it failed to fly. Later, Stringfellow built a steam-driven model which did fly. This was the first successful powered flight of a heavier-than-air craft.
Otto Lilienthal has been called the "Father of Modern Aviation." This German engineer was the first practical aviator. He brought the theory of flight and the practice of flight together by actually riding his gliders into the air and controlling them. He built many single-wing and biwing gliders which he flew by running downhill until sufficient speed was built up to allow them to fly. His gliders had cambered wings and fixed tail surfaces. The last glider he built had movable elevators on the tail. Between 1891 and 1896, he made over 2,000 glides, many of which covered over 700 feet. Unfortunately, he was killed in a gliding accident before he could add an engine to his glider, so he did not have the opportunity to experiment with powered flight. Lilienthal's writings were read worldwide, and pictures of his aircraft accompanied his writings. Photographs of his flights were seen throughout the world and created a great deal of interest in aviation.
An American civil engineer, Octave Chanute, read Lilienthal's works. By 1896, Chanute was performing gliding experiments on the sand dunes around Lake Michigan. Chanute was in his sixties when he became interested in flight, and because of his age, he did no flying. He designed the gliders which were flown by another engineer named A. M. Herring. Chanute is not noted for any outstanding advancement in aeronautics, although he did improve on Lilienthal's work. What he is noted for is his careful study of aviation history and collecting and spreading aviation information.
Another American who entered the field of aviation at this time was Samuel Pierpont Langley. Langley was an astronomer and the director of the Smithsonian Institution in Washington, D.C. His major contribution to flight involved attempts at adding a power plant to a glider. In 1896, he successfully built a steam-powered model which flew for three quarters of a mile before it ran out of fuel. One problem Langley encountered was the extremely heavy weight of steam engines. He was convinced that the internal-combustion gasoline engine held the greatest promise for a lightweight powerful engine for aircraft. Charles M. Manley, Langley's assistant, designed such an engine. By October 1903, the engine had been placed in a lull-size copy of his successful model. The Aerodrome, as Langley called his aircraft, was to be launched by catapult from a barge anchored in the Potomac River. Two attempts were made, both resulting In failure. Unfortunately, both attempts were well attended by the press. Their critical reporting caused the government to withdraw its support, and Langley gave up his project.
At the end of this block of study, you should be able to:
5.56 Discuss the contributions to heavier-than-air flight made by the Wright brothers.
A combination of factors helped the Wright brothers to succeed in controlled, powered,
heavier-than-air flight. First, they had access to knowledge about flight gained by others
before them. Second, they lived at a time when the first practical power plant had been
developed. Finally, they possessed a combination of attitudes and aptitudes which enabled
them to bring the work of all the previous individuals together and combine it into a
successful product. They were patient in their approach to solving any type of problem.
They were also highly creative, had a great deal of personal integrity, and possessed an
outstanding mechanical aptitude.
The Wright brothers' approach to might was first to develop an aircraft which would fly and could be controlled in flight and then to add a power plant. Their observations led them to believe that birds maneuvered in night chiefly by twisting their wings. Using this information, they built a large box kite with four cords attached to the "wingtip" They found that by pulling these cords, and thus twisting (warping) the wings, they could maneuver the kite from the ground.
Following these successful kite flights, the Wrights realized that the next step must be to get into the air themselves to further test their "wing-warping" technique. Before beginning their glider tests, they requested information from the weather bureau as to the site for conducting their tests. They needed a location which would have steady winds and plenty of open space and were advised to try the beaches just south of Kitty Hawk, North Carolina
They selected Kill Devil Hill, North Carolina, for their test, and in October 1900, their first glider was ready. This glider was a biplane with a horizontal elevator in front, no tail, and cords attached to the wingtips for warping them. In order to reduce wind resistance, the pilot rode lying down between the wings. They made a few successful glides during the first winter, but the winds were generally too light for manned flights. For the most part, the first aircraft was also flown as a kite.
The following July, they returned with their second glider which had much larger wings. They also had fastened the wing-warping cables to a cradle in which the pilot lay. The aircraft was controlled by shifting this cradle with the hips, thus tightening the cables and causing the wings to warp. The cables were arranged so that as the rear d one wingtip was warped downward the wingtip on the opposite side was warped upward. This caused the aircraft to turn. This was the first of two great contributions the Wright brothers made toward controlling flight. The Wrights had so many problems with the control of their second glider that after only a month they stopped their tests and returned home to Dayton, Ohio.
During the following months, they built a small wind tunnel and tested many different shapes of wings. These tests gave them the knowledge they needed to overcome the control problems of their second glider.
By September 1902, they built a third glider and returned to North Carolina. This aircraft was basically the same as the first two, with the addition of two fixed vertical fins at the rear. It performed well except that when turning the wing, which was warped downward, It would tend to drag and the aircraft would begin to slide sideways through the air. This was corrected by changing the fixed vertical fins to a single movable rudder which was interconnected with the wing-warping cables. This allowed the rudder to be turned so that the air pressure against it would automatically counteract the drag of the down-warped wing. This was the second great contribution they made toward controlling flight. By the time the Wright brothers returned to Dayton in October, they had performed over 1,000 successful flights and had solved all the major problems of control in the air. Now, all that remained was to add a suitable power plant.
Like others before them, the Wrights found no suitable lightweight engine that would meet their needs. Although they had no experience In power plants, they designed and built a four-cylinder, water-cooled gasoline engine which produced about 12 horsepower. Next, they designed and built the two propellers which would be turned by the engine. The propellers were connected to the engine by a pair of bicycle chains and turned in opposite directions.
By September 1903, the engine had been in stalled and the Wrights returned to North Carolina with their powered aircraft, which they named the Flyer. The Flyer had no wheels but landed in the sand on a pair of skids. For takeoff, they constructed a long wooden rail upon which ran a small trolley. The skids were set on the trolley and a wire held the trolley until the aircraft's engine was running at full power. When the wire was released, the aircraft and trolley ran smoothly down the track until the aircraft lifted off, leaving the trolley behind.
Their first attempt at flight was made on December 14, 1903, with Wilbur at the controls. The Flyer became airborne but stalled and fell back into the sand.
Three days later the damage was repaired. The wind was blowing at over 20 mph. This time, It was Orville's turn so he fitted himself into the cradle. The engine was started and run up to full power, and the wire was released. The Flyer moved down the track, rose into the air, and flew for 12 seconds. One hundred and twenty feet from the end of the track, it slowly settled back onto the sand. It was 10:35 a.m., December 17, 1903. Man's age-old dream of powered, sustained, and controlled heavier-than-air flight was finally a reality*.
The occasion of man's first successful flight went almost unnoticed throughout the world. Only one newspaper published an account of their flight, and this was poorly written and misleading. To prevent any further errors, the Wrights issued a statement to the Associated Press on January 5, 1904, but this was either ignored or hidden inside the papers and printed with no comment.
*George Whitehead (Gustave Weiskopf) is considered by some as being the first to fly, accomplishing this task two years before the Wright Brothers. In the October 1998 issue of "Flight Journal" magazine, there is an article about the controversy over the issue of who was the first to fly (pp. 48-55).
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