Most of the apparatuses in
use towards 1930 were biplanes, that is to say, airplanes with two superposed
wings. Between the wings of the typical biplane there was a nacelle that
was carefully smoothing in its outside and peaked ahead and behind, to
favor that the resistance and the force of drag the device are the lesser
possible necessary to fly it by the air. The aviator and the passengers
were located in this nacelle , that also contained the motor. The propellers
could be located ahead or behind the wings. The airplanes that had the
propellers ahead were called "tractors" and those that had it
behind were known with the "propulsive" name.
The overall length of airplane
was generally a little more than half of the wingspan. In the case of
the tractors type ones , the nacelle extended backwards of the rear end;
but this was not possible in a propulsive type with a helix, because the
nacelle or fuselage, as it is also called, would hinder the operation
of the helix. This difficulty was solved by the device of Gallaudet, which
took part of the fuselage behind the helix on a wide tube that passed
through the bucket of it . In such machines, that were familiarly known
as cellular kites , the tail was maintained by an armor of three or four
props that surrounded the helix. The tail of the apparatus commonly was
formed by four surfaces, two horizontals and two verticals ones. There
was a horizontal fixed tailplane that helped to maintain the stability,
preventing the apparatus to rise, or to descend with too much speed, and
a vertical fin located on the fuselage that helped to balance the apparatus.
In addition to these mechanisms of stabilization, there were the true
control elements: the rudder and the elevator . The elevator was formed
generally by two parts, one on each side of the center, to prevent crushing
the rudder, but rigidly united, so that they could always maneuver together.
The balance of the apparatus
was obtained in most of the cases by means of fins (ailerons), or small
auxiliary winglets, joined to the rear part of the main wings, near the
ends. Sometimes both wings had fins; but more commonly these ones were
installed only in the upper wing. The fins were used in the same way that
the warp concept used by the Wright brothers, they were tugged downwards
in the side that was necessary to elevate, whereas the ones of the opposite
side remained raised. Several small apparatuses were still constructed
towards 1930 with warping ; but the system had not become general, because
it made necessary to debilitate the wings. As it can be seen , the pilot
had to take care of three regulations: rudder, elevator and fins. The
rudder was handled practically in all the models by a revolving bar moved
by the feet, resemblance to the guide of a bicycle. The other two regulations
were driven by means of combinations of wheels and handles; a handle was
moved forwards when the pilot wanted to descend the airplane, and the
inverse movement caused that the apparatus to soar .
As the apparatus needed to
run some stretch by the ground until reaching great speed it had to be
provided with a set of wheels, and as it was important to land on an uneven
surface, it was essential that the apparatus had a landing device carefully
planned (undercarriage) with own means to cushion the shock. Most of these
artifices or devices were made up of two wheels in the front of the fuselage
and below it , so that the propeller did not collide with the ground,
as well as a short skid in the rear part protecting the tail of the plane
of the contact of the ground. The shock absorbers were made of steel some
times, but more frequently they were reduced simply to heavy rubber bands.
The primitive airplanes were
almost entirely made of wood and steel wires; but later the tendency had
been pronounced to use the steel and the duralumin in tubes, whenever
it was possible, due to the most uniform quality, less deterioration and
in many aspects greater facility to work than the wood.
An airplane in flight was similar to a kite; the cord of the kite is replaced
by the motor and the helix of airplane. For a surface to be sustained
in the air it is necessary that it advances through the air , and, therefore,
the machine must apply to it some force that can overcome the resistance
that opposes against the exposed parts of the airplane. In the case of
the kite , this one stays only stationary, and the pressure of the air
is given by the wind that moves. The airplane, when it flew in the air
in calm, before leaving the ground had, nevertheless, to advance at a
certain speed, that depended mainly on the wingspan, of the weight of
the apparatus and the angle that the wings presented to the wind.
The surprising light
and nevertheless powerful motors that has developed the aviation in the
beginnings of the aeronautics .
The air is an element very shaken, the aviator had to maintain a constant
monitoring to avoid the loss of the direction of his apparatus as a result
of the bursts and eddies. Nevertheless, towards the beginnings of the
XX Century stable airplanes begun to be constructed that required less
attention from the pilot. In addition several automatic instruments were
designed, many of them founded on the gyroscope, which acted instantaneously
on the control, correcting immediately any inclination that was not the
horizontal.
By 1920/30s
all airplanes flight by gasoline motors that worked according to the cycle
of Otto of four times, although several years before, the revolving type
of motor seemed the most promising accomplishment of mechanism; but it
was left in most of the heavy apparatuses because of the high consumption
of combustible, and its application had been confined to light exploratory
airplanes and apparatuses used in exhibitions. In the revolving motor,
that has only been used in aeronautical applications, the cylinders, seven
or nine, were located around the crank, like the wheel radii, and the
crank ,instead of rotating as it happens normally, was fixed, whereas
the cylinders and the frame that maintain them turn around it. The most
popular type used in those times was the ordinary vertical motor or "V"
motor, with six, eight or twelve cylinders, and identical in details of
construction and disposition, to the motors of the automobiles of those
times. These motors were wonderfully light. Before the invention of the
automobiles and the airplane. 5.000 kilograms were a very light weight
for a machine of 100 horsepower, but soon the same machine happened to
weigh only 150 kilograms in average .
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Types of airplanes
that were seen in the airfields in the '30s decade. |
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Locating to us temporarily
in the beginnings of the XX century, the airplane that was seen with more
frequency towards the decade of years 1930s in the airfields was the biplane
military tractor of two seats or the commercial modification of the same
one. Also similar apparatuses of smaller dimensions for the transport
of a single person were constructed. They were used for exploration and
war fights and reached speeds in some cases of up to one hundred sixty
kilometers per hour. The other extreme was the multi-engine airplane.
This type of machine had from two to nine motors and one or more helices,
moved by one, two or three motors each one. The greater apparatuses showed
to a great variety of construction and dispositions of the wings. They
had the advantage of greater duration and cargo capacity for a given crew,
and in some cases, due to the possibility of continuing flying after being
damaged one or more motors, they were safer than those smaller ones of
one motor .The motors could be mounted outside the wings in nacelles,
with the helices mounted directly in the motors, or these last ones also
mounted in the fuselage and the helices in the wings.
Of particular interest for
the North Americans were the hydroplanes and the flying boats invented
by Mr. Glenn H. Curtiss, by the double property that they had due their
utility in the defense of the long coastline of the United States and
its application to the sports. These apparatuses lifted off or descended
in the water instead of in the Earth, and could be maneuvered surely in
a sea that would make navigation to a small yacht difficult. Already in
those years they constituted an ideal sports vehicle , because they combined
the emotions of the motor boat with those of the airplane, and virtually
were safe being the sea easy site of descending in case of failures of
the motor or other accidents. They could be transported by boats and be
put at sea by means of cranes. In those years several species of catapults
had also been invented so that they would send directly the hydroplane
to the air from the deck of the ship , if some circumstance prevented
it to be put in the water. The introduction of the airplane carrier ,
a fast ship of great dimensions, with a flight deck free of obstacles
so that the airplane could use it to rise and to settle, originated a
third type of airplane: the amphibian airplane , that could take off from
the Earth and the water. To the terrestrial ordinary type it was also
provided with possible floaters of balloon fabric, plenty of air , to
be used from the ships. When these floaters were deflated, they were folded
inside or to the flank of the fuselage.
In the decade of 1920s an
airplane reached speeds of up to 320 kilometers per hour, several times
quicker than the flight of the fastest birds of which there were news,
constituting a very remarkable fact for that time. It had overcome heights
superior to 11,200 meters on the Earth surface, and could raise to considerable
heights, at the rate of 600 meters per minute. It had conquered the height
of the most formidable mountains having crossed the Atlantic and made
other remarkable flights, among which they were to mention the trip from
England to Australia and from Rome to Tokyo. It had remained in the air
for more than twenty-six hours. In the course of World War I, the incursions
on enemy territory to drop bombs from airplanes were of almost daily accomplishment
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