THE ADVENT OF THE AËROPLANE
The year of 1908 will be memorable in aëronautical science for its
demonstration of the possibility of mechanical flight. Day after day
in France and America was then seen the spectacle of men flying in the
air, with a grace equal to that of the soaring bird. This was done with
a machine not raised by the buoyancy of a gas, but with one that was
heavier than the medium in which it travels, and whose sustentation
and direction was accomplished by dexterity and skill. The experiments
of the brothers Wright were new triumphs of man, new examples of the
old truths that a difficulty is a thing to be overcome, and that the
impossibility of to-day may be the achievement of to-morrow. This
progress in human flight was not the result of any new discovery; it
was the sequence of a long series of experiments; nor was it one
nation only that forged the links that connected past researches to the
successful issues of the present century.
It is, however, not without honour to the British nation that one of
the fundamental principles of the biplane was proposed and elucidated
by a Briton in 1866. I refer to the important principle of superposed
surfaces advanced in that year by the late F. H. Wenham. He pointed
out that the lifting power of such a surface can be most economically
obtained by placing a number of small surfaces above each other. Wenham
built flying machines on this principle with appliances for the use of
his own muscular power. He obtained valuable results as to the driving
power of his superposed surfaces, but he did not accomplish flight.
In 1872, H. von Helmholtz emphasised the improbability that man would
ever be able to drive a flying machine by his own muscular exertion.
After his statements there came a period of stagnation in the attempts
to navigate the air by bodies heavier than air.
It is difficult to say how much aëronautical science owes to two
illustrious names--Sir Hiram Maxim and the late Professor Langley.
The two eminent men took up the subject of flight about the same
time in the last decade of the last century, and applied to it all
the scientific knowledge of the time. The flying machine had come to
be associated in the public mind with foolhardiness and failure. In
the discussion following Sir Hiram Maxim’s paper, “Experiments in
Aëronautics,” read before the Society of Arts on November 28th, 1894,
he said, “At the time I took up this subject it was almost considered
a disgrace for anyone to think of it; it was quite out of the question
practically.” But these two scientific men stepped into the breach,
rescued aëronautics from a fallen position, and fired in its cause the
enthusiasm of men of light and leading.
Sir Hiram Maxim built the largest flying machine that had been
constructed. It spread 4,000 square feet of supporting surface, and
weighed 8,000 lb. The screw propellers were no less than 17 feet 11
inches in diameter, the width of the blade at the tip being 5 feet.
The boiler was of 363 h.p. The machine ran on wheels on a railway
line, and was restrained from premature flight by two wooden rails
placed on each side above the wheels. On one occasion, however, the
machine burst through the wooden rails and flew for 300 feet.
In 1896 Langley’s tandem-surfaced model aërodrome had luck with the
aërial currents, and flew for more than three-quarters of a mile over
the Potomac River. This machine had 70 square feet supporting surface,
weighed 72 lb., and had an engine of 1 h.p., weighing 7 lb. It is well
known how, in later years, Langley exaggerated his model into a machine
which carried a man, and how twice, when it was put to the test over
water, at the very moment of being launched, it caught in the launching
ways and was pulled into the water. It is interesting to note that
the American aviator, Mr. Curtiss, has lately unearthed the Langley
flying machine, and flown on it. Thus to Langley has come a posthumous
aëronautical honour.
Lilienthal, in Germany, in considering equilibrium, experimented with
what are called gliding machines--aëroplanes which are launched from
some hillside against the wind, and depend upon gravity for their
motive power. In this way the art of balancing could be practised on
motorless gliders. With Lilienthal commenced the age of systematic
experimental flight; he made the discovery of the driving forward
of arched surfaces against the wind; he made some 2,000 glides,
and sometimes from a height of 30 metres he glided 300 metres. The
underlying principle of maintaining equilibrium in the air has been
recognised to be that the centre of pressure should at all times be on
the same vertical line as the centre of gravity due to the weight of
the apparatus. Lilienthal sought to keep his balance by altering the
position of his centre of gravity by movements of his body. One day he
was upset by a side gust and was killed. Pilcher, in England, took up
his work. With his soaring machines he made some hundred glides, but he
also made one too many. One day, in 1899, in attempting to soar from
level ground by being towed by horses, his machine broke, and he fell
to the ground. He died shortly afterwards, a British martyr of the air.
Mr. Octave Chanute’s experiments in 1896–1902 formed important links
in flight development. He first introduced the vital principle of
making the surfaces movable instead of the aviator, and he made use of
superposed surfaces. Though his work was a stage in the development of
the flying machine, it was reserved to two other geniuses, the brothers
Wright, to bring flight to a point of progress where prejudiced critics
would be for ever silenced.
The brothers Wright first carried out laboratory experiments; they
then, in 1900, first began to experiment with gliding machines at Kitty
Hawk, North Carolina. With the comparatively small surfaces (15.3
square metres) they used in that year, they endeavoured to raise the
machine by the wind like a kite; but finding that it often blew too
strongly for such a system to be practical, in 1901 they abandoned the
idea and resorted to gliding flight.
These machines of 1901 had two superposed surfaces, 1.73 metres apart,
each being 6.7 metres from tip to tip, 2.13 metres wide, and arched
1-19th. The total supporting surface was 27 square metres. They
dispensed with the tail which previous experimenters had considered
necessary. Instead, they introduced into their machine two vital
principles, upon which not only the success of their preliminary
gliding experiments depended, but also their later ones with their
motor-driven aëroplanes--(1) the hinged horizontal rudder in front for
controlling the vertical movements of the machine; (2) the warping or
flexing of one wing or the other for steering to right or left.
Later, a vertical rudder was also added for horizontal steering.
The combined movements of these devices maintained equilibrium. The
importance of the system of torsion of the main carrying surfaces
cannot be overestimated. We have only to look to nature for its _raison
d’être_, and observe a flight of seagulls over the sea: how varied are
the flexings of nature’s aëroplanes in their wondrous manœuvrings to
maintain and recover equilibrium! Since the appearance of the Wright
motor-driven aëroplane, the principle of moving either the main
surface or attachments to the main surface has been very generally
adopted in other types of flying machines. A feature of these early
experiments was the placing of the operator prone upon the gliding
machine, instead of in an upright position, to secure greater safety
in alighting, and to diminish the resistance. This, however, was
only a temporary expedient while the Wrights were feeling their way.
In the motor-driven aëroplanes the navigator and his companion were
comfortably seated. After the experiments of 1901, the Wrights carried
on laboratory researches to determine the amount and direction of the
pressures produced by the wind upon planes and arched surfaces exposed
at various angles of incidence. They discovered that the tables of the
air pressures which had been in use were incorrect. Upon the results
of these experiments they produced, in 1902, a new and larger machine.
This had 28.44 square metres of sustaining surfaces--about twice the
area that previous experimenters had dared to handle. The machine was
first flown as a kite, so that it might be ascertained whether it
would soar in a wind having an upward trend of a trifle over seven
degrees; and this trend was found on the slope of a hill over which
the current was flowing. Experiment showed that the machine soared
under these circumstances whenever the wind was of sufficient force to
keep the angle of incidence between four and eight degrees. Hundreds
of successful glides were made along the full length of this slope,
the longest being 22½ feet, and the time 26 seconds. A motor and screw
propellers were then applied in place of gravity, in 1903, and four
flights made, the first lasting 12 seconds, and the last 59 seconds,
when 260 metres were covered at a height of two metres.
In 1904, several hundred flights were made, some being circular.
All this work was carried on in a secluded spot and unpublished. In
December, 1905, the world was startled by the news that the brothers
Wright had flown for 24¼ miles in half an hour, at a speed of 38
miles an hour. More than this at the time the brothers would not say,
and for three years the world thirsted for the fuller knowledge only
revealed in 1908. In the interval some went so far as to distrust the
statements of the brothers Wright; but those who, like myself, had had
the privilege of correspondence with them from their first experiments
felt the fullest confidence that every statement they had made was fact.
I have somewhat dwelt on the preliminary experiments of the brothers
Wright with their gliding structures as indicating the rapidity of
progress attained when sound scientific method is combined with
practical experiment. Too often in the past there has been a tendency
amongst the workers in science to keep theory and practice apart. They
are, however, interdependent. Each has a corrective influence on the
other.
To the labours of the Wright brothers we certainly owe the advent of
the mobile and truly efficient military air scout. It is their efforts
that have revolutionised warfare. In the present war we see only the
beginnings of what will one day be; but they are none the less truly
prophetic.
It was the enthusiastic Captain Ferber, who later became a victim
to his ardour for aërial achievement, who realised what the brothers
Wright had accomplished for military aëronautics. The latter having
entered into communications with the French Government respecting
the sale of their machines, Captain Ferber was deputed by the French
Government to go to America and report on their claims. As the brothers
Wright at that time so carefully guarded the secrecy of their details,
he was not allowed to see the machine when he arrived, and had to be
content with the mere hearsay of certain persons at Ohio, who had
witnessed their flights. But he had sufficient faith in the brothers
Wright to recommend the French Government to buy their invention.
The negotiations, however, fell through at the time, but in 1908 Wilbur
Wright came to France to carry on experiments at Le Mans, while his
brother, Mr. Orville Wright, went to Fort Myers in America.
In Wilbur Wright’s machine at Le Mans, the two superposed slightly
concave surfaces were about 12.50 metres long and 2 metres wide.
They were separated by a distance of 1.80 metres. At a distance of 3
metres from the main supporting surfaces was the horizontal rudder
for controlling the vertical motions; this was composed of two oval
superposed planes. At 2.50 metres in front of the main supporting
surfaces was the vertical rudder, composed of two vertical planes.
The 25 h.p. motor was placed on the lower aëro-surface; this weighed
ninety kilogrammes. At the left of the motor were the two seats, side
by side, for the aëronaut and his companion. The two wooden propellers
at the back of the machine were 2.50 metres in diameter. They revolved
at the rate of 450 revolutions per minute.
The area of the sustaining surfaces was fifty square metres. The weight
of the whole machine (with aviator) was about 450 kilogrammes. Levers
under the control of the aviator regulated the various functions of the
machine, the flexing of the carrying surfaces, the movements of the
horizontal rudders, the vertical rudder, etc.
Soon after the experiments at Le Mans had commenced there came the
news of the accident to Mr. Orville Wright’s machine in America, in
which the latter’s leg was broken and Lieutenant Selfridge was killed.
This was a critical moment for aëronautical science. I can myself
bear witness to its depressing effect on an illustrious aëronautical
assemblage, for I was myself present at Wilbur Wright’s aëroplane shed
when the telegram came bearing the sad news. The sacrifice of one life
at that moment seemed to counterbalance the advantages gained by the
triumph of the brothers Wright. Even Wilbur Wright himself seemed to
half repent he had conquered the air! He exclaimed, “It seems all my
fault.” It was, indeed, then little thought what the future toll of the
air would have to be.
Fortunately for aëronautical progress, two days afterwards Wilbur
Wright recovered his nerve, and made the convincing flight of 1 hour 31
minutes 25 4-5th seconds.
From that day onwards there has been an increasing flow of progress in
the mastery of the air.