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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.
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Leonardo da Vinci |
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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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