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The world in the 30's . History of the aeronautics. The Old Times - Los Viejos Tiempos | Español : Historia de la Aeronáutica
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THE HUMAN FLIGHT
How the man can fly today much quicker than the birds, whose flight he has imitated.
Flight of Otto Lilienthal in his apparatus
THE WONDERFUL DEVELOPMENT OF THE AERONAUTICS
If we consider the set of technological achievements developed until the decade of the 30's in XXth. Century , we can observe that no branch of the science existed in which there was greater increase seen in the one hundred previous years than that one corresponding to the airplane navigation. It had passed hardly a generation since the first mechanical flight took place, and in this brief time interval, the airplane and the airship had gotten to occupy a place between the usual vehicles being used just like the streetcar or the automobile. The transatlantic flights and the regular mail transport by airplane were facts that had passed to the category of the ordinary.
With regards to the military use of the Air Force, the extension of the combat to the air regions had made a revolution in the practice of the art of war: already from those times, a nation that began a war without an extensive aircraft equipment, would commit a true madness. The general who lacked aerial explorers was like in the case of a player who did his game bandaged against an opponent who did not undergo such disadvantage.
In the Mythology and in the history of the Middle Ages several attempts of flight were registered; perhaps the most important was that one made by the Italian artist and scientist Leonardo da Vinci. But what it was obtained mostly in these tests were short and unstable planning. Most of them failed by constituting a too servile imitation of the nature, since the attempts were always made copying the wings of the birds. The first among them who we can indicate as starter of the modern period of experimentation was an Englishman : Sir George Cayley.
In 1796, Cayley constructed several toy
helicopters , apparatuses provided with propellers instead of wings, and
he tested them, with interesting results. The driving force was provided
by the elasticity of a piece of bent metal spiral. As this procedure did
not give a satisfactory solution to the problem of the airplane navigation,
he tried another method, and it is already more than two hundred years
ago when he made a scrupulous study of the forces that the wind exerts
on a flat surface. He also demonstrated the advantages of the curved section
of the wings with a strongly inclined edge forwards. Having this concepts
as a base he projected and constructed an airplane, that was not very
different in its fundamental characteristics than the apparatuses in use
towards the first decades of XX Century. This machine was lifted to the
top of a hill and planned downwards to the valley following a slope of
about eight degrees of inclination. Also when a man ran in a flat land
towing the apparatus sometimes he managed to rise and fly in small distances.
Cayley, nevertheless, like all the constructors of the first times, was
not able to advance in his tests due to the lack of a motor suitable for
his model. When Boulton and Watt constructed their steam engine, he welcomed
it eagerly, thinking that it would facilitate him the means to obtain
the mechanical flight , and according to the calculations that he left
when dying, his airplane moved by steam motor would need a weight about
80 kilograms by horsepower. Sir George Cayley did not get to assemble
a motor to his airplanes; but besides to formulate the first principles
of the aerodynamics and to study the steam engine, he prophesied the coming
of the lighter motors of internal combustion.
The first man who flew in Europe, Wilbur Wright in his biplane in Pau in 1908.
The very important experiments of Henson and Stringfellow
The experiments that followed in importance to those of Cayley were made towards 1840 by William Samuel Henson, helped by John Stringfellow. The notes of Henson describe a monoplane provided with a steam engine, that drove two pusher propellers, located behind the wings. The wings were handled, practically, of an identical way to which it was still used later in many great monoplanes. The apparatus moved by the ground on three wheels, until reaching the speed of the flight, and was provided for the keep the direction with a vertical rudder and another depth horizontal one , both in the tail.
Orville Wright doing his first flight on December 17 , 1903, making a perfect flight of 59 seconds of duration, in Kitty Hawk.
Its aspect was of an excellent form, having place for the motor and passengers. In summary: except for what referred to the motor, the airplane of Henson was completely handy , and it would not look rare next to the models of the years 1911 or 1912. The first tests were made successfully in a small model whose energy was provided by a steel spring. Later a greater model was constructed, that was of about six meters wingspan, powered by a steam motor; but it was not able to reach a good stability , and the device tended to overturn when rolling on the ground.
| Stringfellow,
first constructor of a maneuverable airplane with motor . |
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These experiments were made to a large
extent in 1843. Several years later Henson marched to the United States
of America and Stringfellow continued his work alone. From 1846 to 1848
he was busy in the construction of a small model, of three meters of wingspan,
very similar in design to the one constructed by Henson, but with the
wings better shaped, which weighed, including the steam engine, four kilograms
approximately. This machine was tested in a great abandoned open space
at a factory, and there it made successfully flights of more than thirty
and six meters long in several occasions being the flight limited by the
walls of the warehouses. To Stringfellow, therefore, must correspond the
glory of being the first man of the world that constructed a maneuverable
airplane provided with a motor. Nevertheless, it is doubtful that his
experiments had ever been successful outdoors, where atmospheric conditions
are much more variable. After this result he left the tests done for some
time, until being newly attracted by them during the formation of the
Aeronautical Society of Great Britain and Ireland. Taking advantage of
the work of Wenham, he constructed a triplane, that was exposed in the
Crystal Palace in London, in 1868, and which elevated its own weight successfully,
by means of the boost of a horse-power approximately .
| Wenham and the principle of relation of surface of the wings . Mr. F. H. Wenham began to be interested in the artificial flight, as a result of the study of the birds. He made extensive investigations on the their flight to many different species , determining the weight transported by square centimeter, the delivered thrust, etc. As a result of his studies, he established a principle that had not been observed at all until then, although Henson and Stringfellow made use of it in their apparatuses. It says that the quotient of the length by the width of the wings, or " form relation ", as is called now, is of great importance, and that the longest and narrow wings always give the best results while maintaining the other conditions. Known this fact , it only took a step to project an apparatus that had a certain number of long and narrow surfaces superposed with the advantage of the characteristic before mentioned , without finding the structural difficulties that aroused during the construction of a simple wing of great wingspan, being, however, reasonable its weight. The apparatus of Wenham had, nevertheless, simply united by struts surfaces at intervals that comprised the main frame, thus preventing that the wing took an inconvenient and equal curvature, making impossible that the surface stayed flat, since the pressure of the air loosed quickly and stretched the fabric in the parts not fastened. |
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| Wenham made
several tests of flight, but he never achieved great success, and
his name is remembered solely by his theories and studies, because
he achieved nothing practical . All the mentioned inventors were English,
because in first half of the XIX Century, the attention of the French
and the others that studied the problems of the aeronautics was directed
mainly to the aerostation. Nevertheless, at this time the problem
was the quite close to the solution to attract the universal attention.
The first French remarkable experimenters were the captain Le Bris
and Louis Mouillard. Both constructed gliders, with which, according
to what it seems, they had achieved at least as much success as any
other of their predecessors, although the results, specially those
ones reached by Le Bris , were of scarce importance. Mouillard also
wrote a book quite suggestive: L'empire de l'air. In 1871 and 1872, A. Renaud constructed several models of diverse types, most of them moved by a twisted rubber cord. He constructed helicopters similar to those ones of Sir George Cayley, apparatuses of movable wings and airplane with propellers. One of these last ones made a flight of more than 40 meters. Near eight years later, M. Víctor Tatín constructed a greater model, using a compressed air motor that weighed, approximately two kilograms. This model flew about 15 meters. We must now return a few years before to review of the work of Otto Lilienthal in Germany. Lilienthal, like so many others, began by the study of the flight of the birds; but soon he saw what the others had not observed , and it was the concept that the flight is a problem as much of construction as of handling of the apparatus, and that it could not give a good result an apparatus in the air into the hands of a man who did not have enough experience to pilot it nor knew how to keep the balance, because in this case inevitably he would destroy it. He began, therefore, to acquire the necessary practice, using a glider. His first apparatus was a monoplane constructed in 1891 and capable to do flights of considerable length, launching himself from the top of a hill. All the apparatuses of Lilienthal had tail, formed by horizontal and vertical surfaces; but it was necessary that the pilot balance his weight moving his feet, to prevent that the glider come down. Such method of guidance was heavy and uncomfortable, adapted solely to very light apparatuses. Lilienthal, in spite of this disadvantage, made near 2,000 happy flights with monoplanes and biplanes. He was indeed on the verge of adapting a motor to his last glider when he killed himself in an accident on August of 1896, as a result of the breakage of his apparatus. He made an important study on the properties of the curved wings and demonstrated that the pressure onto a surface of this class could be inclined more forwards than the perpendicular to the wing, on the contrary to what had been believed until then. Lilienthal recognized the defects of his system of balance, and by a letter that he wrote a few weeks before his death it seems that at that time he had invented a very perfected method that eliminated the deviation of the weight and that he was ready to try. |
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