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The EARLY HISTORY of the AIRPLANE
The DAYTON-WRIGHT AIRPLANE CO.
DAYTON OHIO
The Wright Brothers' Aeroplane
_By Orville and Wilbur Wright_
Though the subject of aerial navigation is generally considered new, it
has occupied the minds of men more or less from the earliest ages. Our
personal interest in it dates from our childhood days. Late in the
autumn of 1878 our father came into the house one evening with some
object partly concealed in his hands, and before we could see what it
was, he tossed it into the air. Instead of falling to the floor, as we
expected, it flew across the room, till it struck the ceiling, where it
fluttered awhile, and finally sank to the floor. It was a little toy,
known to scientists as a "helicoptere," but which we, with sublime
disregard for science, at once dubbed a "bat." It was a light frame of
cork and bamboo, covered with paper, which formed two screws, driven in
opposite directions by rubber bands under torsion. A toy so delicate
lasted only a short time in the hands of small boys, but its memory was
abiding.
Several years later we began building these helicopteres for ourselves,
making each one larger than that preceding. But, to our astonishment, we
found that the larger the "bat" the less it flew. We did not know that a
machine having only twice the linear dimensions of another would require
eight times the power. We finally became discouraged, and returned to
kite-flying, a sport to which we had devoted so much attention that we
were regarded as experts. But as we became older we had to give up this
fascinating sport as unbecoming to boys of our ages.
It was not till the news of the sad death of Lilienthal reached America
in the summer of 1896 that we again gave more than passing attention to
the subject of flying. We then studied with great interest Chanute's
"Progress in Flying Machines," Langley's "Experiments in Aerodynamics,"
the "Aeronautical Annuals" of 1905, 1906, and 1907, and several
pamphlets published by the Smithsonian Institution, especially articles
by Lilienthal and extracts from Mouillard's "Empire of the Air." The
larger works gave us a good understanding of the nature of the flying
problem, and the difficulties in past attempts to solve it, while
Mouillard and Lilienthal, the great missionaries of the flying cause,
infected us with their own unquenchable enthusiasm, and transformed idle
curiosity into the active zeal of workers.
In the field of aviation there were two schools. The first,
represented by such men as Professor Langley and Sir Hiram Maxim,
gave chief attention to power flight; the second, represented by
Lilienthal, Mouillard, and Chanute, to soaring flight. Our sympathies
were with the latter school, partly from impatience at the wasteful
extravagance of mounting delicate and costly machinery on wings
which no one knew how to manage, and partly, no doubt, from the
extraordinary charm and enthusiasm with which the apostles of soaring
flight set forth the beauties of sailing through the air on fixed
wings, deriving the motive power from the wind itself.
The balancing of a flyer may seem, at first thought, to be a very simple
matter, yet almost every experimenter had found in this one point which
he could not satisfactorily master. Many different methods were tried.
Some experimenters placed the center of gravity far below the wings, in
the belief that the weight would naturally seek to remain at the lowest
point. It is true, that, like the pendulum, it tended to seek the lowest
point; but also, like the pendulum, it tended to oscillate in a manner
destructive of all stability. A more satisfactory system, especially for
lateral balance, was that of arranging the wings in the shape of a broad
V, to form a dihedral angle, with the center low and the wing-tips
elevated. In theory this was an automatic system, but in practice it had
two serious defects: first, it tended to keep the machine oscillating;
and second, its usefulness was restricted to calm air.
In a slightly modified form the same system was applied to the
fore-and-aft balance. The main aeroplane was set at a positive angle,
and a horizontal tail at a negative angle, while the center of gravity
was placed far forward. As in the case of lateral control, there was a
tendency to constant undulation, and the very forces which caused a
restoration of balance in calms caused a disturbance of the balance in
winds. Notwithstanding the known limitations of this principle, it had
been embodied in almost every prominent flying machine which had been
built.
After considering the practical effect of the dihedral principle, we
reached the conclusion that a flyer founded upon it might be of interest
from a scientific point of view, but could be of no value in a practical
way. We therefore resolved to try a fundamentally different principle.
We would arrange the machine so that it would not tend to right itself.
We would make it as inert as possible to the effects of change of
direction or speed, and thus reduce the effects of wind-gusts to a
minimum. We would do this in the fore-and-aft stability by giving the
aeroplanes a peculiar shape; and in the lateral balance by arching the
surfaces from tip to tip, just the reverse of what our predecessors had
done. Then by some suitable contrivance, actuated by the operator,
forces should be brought into play to regulate the balance.
Lilienthal and Chanute had guided and balanced their machines, by
shifting the weight of the operator's body. But this method seemed
to us incapable of expansion to meet large conditions, because the
weight to be moved and the distance of possible motion were limited,
while the disturbing forces steadily increased, both with wing area
and with wind velocity. In order to meet the needs of large machines,
we wished to employ some system whereby the operator could vary at
will the inclination of different parts of the wings, and thus obtain
from the wind forces to restore the balance which the wind itself had
disturbed. This could easily be done by using wings capable of being
warped, and by supplementary adjustable surfaces in the shape of
rudders. As the forces obtainable for control would necessarily
increase in the same ratio as the disturbing forces, the method
seemed capable of expansion to an almost unlimited extent. A
happy device was discovered whereby the apparently rigid system
of superposed surfaces, invented by Wenham, and improved by
Stringfellow and Chanute, could be warped in a most unexpected
way, so that the aeroplanes could be presented on the right and
left sides at different angles to the wind. This, with an adjustable,
horizontal front rudder, formed the main feature of our first glider.
The period from 1885 to 1900 was one of unexampled activity in
aeronautics, and for a time there was high hope that the age of flying
was at hand. But Maxim, after spending $100,000, abandoned the work;
the Ader machine, built at the expense of the French Government, was a
failure; Lilienthal and Pilcher were killed in experiments; and Chanute
and many others, from one cause or another, had relaxed their efforts,
though it subsequently became known that Professor Langley was still
secretly at work on a machine for the United States Government. The
public, discouraged by the failures and tragedies just witnessed,
considered flight beyond the reach of man, and classed its adherents
with the inventors of perpetual motion.
We began our active experiments at the close of this period, in October,
1900, at Kitty Hawk, North Carolina. Our machine was designed to be
flown as a kite, with a man on board, in winds from 15 to 20 miles an
hour. But, upon trial, it was found that much stronger winds were
required to lift it. Suitable winds not being plentiful, we found it
necessary, in order to test the new balancing system, to fly the machine
as a kite without a man on board, operating the levers through cords
from the ground. This did not give the practice anticipated, but it
inspired confidence in the new system of balance.
In the summer of 1901 we became personally acquainted with Mr. Chanute.
When he learned that we were interested in flying as a sport, and not
with any expectation of recovering the money we were expending on it, he
gave us much encouragement. At our invitation, he spent several weeks
with us at our camp at Kill Devil Hill, four miles south of Kitty Hawk,
during our experiments of that and the two succeeding years. He also
witnessed one flight of the power machine near Dayton, Ohio, in October,
1904.
The machine of 1901 was built with the shape of surface used by
Lilienthal, curved from front to rear like the segment of a parabola,
with a curvature 1/12 the depth of its cord; but to make doubly sure
that it would have sufficient lifting capacity when flown as a kite in
15 or 20-mile winds, we increased the area from 165 square feet, used in
1900, to 308 square feet--a size much larger than Lilienthal, Pilcher,
or Chanute had deemed safe. Upon trial, however, the lifting capacity
again fell very far short of calculation, so that the idea of securing
practice while flying as a kite had to be abandoned. Mr. Chanute, who
witnessed the experiments, told us that the trouble was not due to poor
construction of the machine. We saw only one other explanation--that the
tables of air-pressures in general use were incorrect.
[Illustration]
We then turned to gliding--coasting downhill on the air--as the only
method of getting the desired practice in balancing a machine. After
a few minutes' practice we were able to make glides of over 300 feet,
and in a few days were safely operating in 27-mile winds. In these
experiments we met with several unexpected phenomena. We found that,
contrary to the teachings of the books, the center of pressure on a
curved surface traveled backward when the surface was inclined, at small
angles, more and more edgewise to the wind. We also discovered that in
free flight, when the wing on one side of the machine was presented to
the wind at a greater angle than the one on the other side, the wing
with the greater angle descended, and the machine turned in a direction
just the reverse of what we were led to expect when flying the machine
as a kite. The larger angle gave more resistance to forward motion, and
reduced the speed of the wing on that side. The decrease in speed more
than counterbalanced the effect of the larger angle. The addition of a
fixed vertical vane in the rear increased the trouble, and made the
machine absolutely dangerous. It was some time before a remedy was
discovered. This consisted of movable rudders working in conjunction
with the twisting of the wings. The details of this arrangement are
given in specifications published several years ago.
The experiments of 1901 were far from encouraging. Although Mr. Chanute
assured us that, both in control and in weight carried per horse-power,
the results obtained were better than those of any of our predecessors,
yet we saw that the calculations upon which all flying machines had been
based were unreliable, and that all were simply groping in the dark.
Having set out with absolute faith in the existing scientific data, we
were driven to doubt one thing after another, till finally, after two
years of experiment, we cast it all aside, and decided to rely entirely
upon our own investigations. Truth and error were everywhere so
intimately mixed as to be undistinguishable. Nevertheless, the time
expended in preliminary study of books was not misspent, for they gave
us a good general understanding of the subject, and enabled us at the
outset to avoid effort in many directions in which results would have
been hopeless.
The standard measurements of wind-pressures is the force produced by a
current of air of one mile per hour velocity striking square against a
plane of one square foot area. The practical difficulties of obtaining
an exact measurement of this force have been great. The measurements by
different recognized authorities vary 50 per cent. When this simplest of
measurements presents so great difficulties, what shall be said of the
troubles encountered by those who attempt to find the pressure at each
angle as the plane is inclined more and more edgewise to the wind? In
the eighteenth century the French Academy prepared tables giving such
information, and at a later date the Aeronautical Society of Great
Britain made similar experiments. Many persons likewise published
measurements and formulas; but the results were so discordant that
Professor Langley undertook a new series of measurements, the results
of which form the basis of his celebrated work, "Experiments in
Aerodynamics." Yet a critical examination of the data upon which he
based his conclusions as to the pressures at small angles shows
results so various as to make many of his conclusions little better
than guesswork.
To work intelligently, one needs to know the effects of a multitude
of variations that could be incorporated in the surfaces of flying
machines. The pressures on squares are different from those on
rectangles, circles, triangles, or ellipses; arched surfaces differ
from planes, and vary among themselves according to the depth of
curvature; true arcs differ from parabolas, and the latter differ
among themselves; thick surfaces differ from thin, and surfaces
thicker in one place than another vary in pressure when the positions
of maximum thickness are different; some surfaces are most efficient
at one angle, others at other angles. The shape of the edge also makes
a difference, so that thousands of combinations are possible in so
simple a thing as a wing.
We had taken up aeronautics merely as a sport. We reluctantly entered
upon the scientific side of it. But we soon found the work so
fascinating that we were drawn into it deeper and deeper. Two testing
machines were built, which we believed would avoid the errors to which
the measurements of others had been subject. After making preliminary
measurements on a great number of different-shaped surfaces, to secure a
general understanding of the subject, we began systematic measurements
of standard surfaces, so varied in design as to bring out the underlying
causes of differences noted in their pressures. Measurements were
tabulated on nearly 50 of these at all angles from zero to 45 degrees at
intervals of 2-1/2 degrees. Measurements were also secured showing the
effects on each other when surfaces are superposed, or when they follow
one another.
Some strange results were obtained. One surface, with a heavy roll at
the front edge, showed the same lift for all angles from 7-1/2 to 45
degrees. A square plane, contrary to the measurements of all our
predecessors, gave a greater pressure at 30 degrees than at 45 degrees.
This seemed so anomalous that we were almost ready to doubt our own
measurements, when a simple test was suggested. A weather-vane, with two
planes attached to the pointer at an angle of 80 degrees with each
other, was made. According to our tables, such a vane would be in
unstable equilibrium when pointing directly into the wind; for if by
chance the wind should happen to strike one plane at 39 degrees and the
other at 41 degrees, the plane with the smaller angle would have the
greater pressure, and the pointer would be turned still farther out of
the course of the wind until the two vanes again secured equal
pressures, which would be at approximately 30 and 50 degrees. But the
vane performed in this very manner. Further corroboration of the tables
was obtained in experiments with the new glider at Kill Devil Hill the
next season.
In September and October, 1902, nearly 1,000 gliding flights were made,
several of which covered distances of over 600 feet. Some, made against
a wind of 36 miles an hour, gave proof of the effectiveness of the
devices for control. With this machine, in the autumn of 1903, we made a
number of flights in which we remained in the air for over a minute,
often soaring for a considerable time in one spot, without any descent
at all. Little wonder that our unscientific assistant should think the
only thing needed to keep it indefinitely in the air would be a coat of
feathers to make it light!
With accurate data for making calculations, and a system of balance
effective in winds as well as in calms, we were now in a position, we
thought, to build a successful power-flyer. The first designs provided
for a total weight of 600 lbs., including the operator and an eight
horse-power motor. But, upon completion, the motor gave more power than
had been estimated, and this allowed 150 lbs. to be added for
strengthening the wings and other parts.
Our tables made the designing of the wings an easy matter, and as
screw-propellers are simply wings traveling in a spiral course, we
anticipated no trouble from this source. We had thought of getting the
theory of the screw-propeller from the marine engineers, and then, by
applying our tables of air-pressures to their formulas, of designing
air-propellers suitable for our purpose. But so far as we could learn,
the marine engineers possessed only empirical formulas, and the exact
action of the screw-propeller, after a century of use, was still very
obscure. As we were not in a position to undertake a long series of
practical experiments to discover a propeller suitable for our machine,
it seemed necessary to obtain such a thorough understanding of the
theory of its reactions as would enable us to design them from
calculations alone. What at first seemed a problem became more complex
the longer we studied it. With the machine moving forward, the air
flying backward, the propellers turning sidewise, and nothing standing
still, it seemed impossible to find a starting-point from which to trace
the various simultaneous reactions. Contemplation of it was confusing.
After long arguments we often found ourselves in the ludicrous position
of each having been converted to the other's side, with no more
agreement than when the discussion began.
[Illustration]
It was not till several months had passed, and every phase of the
problem had been thrashed over and over, that the various reactions
began to untangle themselves. When once a clear understanding had been
obtained there was no difficulty in designing suitable propellers, with
proper diameter, pitch, and area of blade, to meet the requirements of
the flyer. High efficiency in a screw-propeller is not dependent upon
any particular or peculiar shape; and there is no such thing as a "best"
screw. A propeller giving a high dynamic efficiency when used upon one
machine may be almost worthless when used upon another. The propeller
should in every case be designed to meet the particular conditions of
the machine to which it is to be applied. Our first propellers, built
entirely from calculation, gave in useful work 66 per cent. of the power
expended. This was about one-third more than had been secured by Maxim
or Langley.
The first flights with the power machine were made on December 17, 1903.
Only five persons besides ourselves were present. These were Messrs.
John T. Daniels, W. S. Dough, and A. D. Etheridge, of the Kill Devil
Life-Saving Station; Mr. W. C. Brinkley, of Manteo; and Mr. John Ward,
of Naghead. Although a general invitation had been extended to the
people living within five or six miles, not many were willing to face
the rigors of a cold December wind in order to see, as they no doubt
thought, another flying machine not fly. The first flight lasted only 12
seconds, a flight very modest compared with that of birds, but it was,
nevertheless, the first in the history of the world in which a machine
carrying a man had raised itself by its own power into the air in free
flight, had sailed forward on a level course without reduction of speed,
and had finally landed without being wrecked. The second and third
flights were a little longer, and the fourth lasted 59 seconds, covering
a distance of 852 feet over the ground against a 20-mile wind.
After the last flight the machine was carried back to camp and set down
in what was thought to be a safe place. But a few minutes later, while
we were engaged in conversation about the flights, a sudden gust of wind
struck the machine, and started to turn it over. All made a rush to stop
it, but we were too late. Mr. Daniels, a giant in stature and strength,
was lifted off his feet, and falling inside, between the surfaces, was
shaken about like a rattle in a box as the machine rolled over and over.
He finally fell out upon the sand with nothing worse than painful
bruises, but the damage to the machine caused a discontinuance of
experiments.
In the spring of 1904, through the kindness of Mr. Torrence Huffman, of
Dayton, Ohio, we were permitted to erect a shed, and to continue
experiments, on what is known as the Huffman Prairie, at Simms Station,
eight miles east of Dayton. The new machine was heavier and stronger,
but similar to the one flown at Kill Devil Hill. When it was ready for
its first trial every newspaper in Dayton was notified, and about a
dozen representatives of the Press were present. Our only request was
that no pictures be taken, and that the reports be unsensational, so as
not to attract crowds to our experiment grounds. There were probably 50
persons altogether on the ground. When preparations had been completed a
wind of only three or four miles was blowing--insufficient for starting
on so short a track--but since many had come a long way to see the
machine in action, an attempt was made. To add to the other difficulty,
the engine refused to work properly. The machine, after running the
length of the track, slid off the end without rising into the air at
all. Several of the newspaper men returned the next day, but were again
disappointed. The engine performed badly, and after a glide of only 60
feet, the machine came to the ground. Further trial was postponed till
the motor could be put in better running condition. The reporters had
now, no doubt, lost confidence in the machine, though their reports, in
kindness, concealed it. Later, when they heard that we were making
flights of several minutes' duration, knowing that longer flights had
been made with airships, and not knowing any essential difference
between airships and flying machines, they were but little interested.
We had not been flying long in 1904 before we found that the problem of
equilibrium had not as yet been entirely solved. Sometimes, in making a
circle, the machine would turn over sidewise despite anything the
operator could do, although, under the same conditions in ordinary
straight flight, it could have been righted in an instant. In one
flight, in 1905, while circling around a honey locust tree at a height
of about 50 feet, the machine suddenly began to turn up on one wing, and
took a course toward the tree. The operator, not relishing the idea of
landing in a thorn-tree, attempted to reach the ground. The left wing,
however, struck the tree at a height of 10 or 12 feet from the ground
and carried away several branches; but the flight, which had already
covered a distance of six miles, was continued to the starting-point.
The causes of these troubles--too technical for explanation here--were
not entirely overcome till the end of September, 1905. The flights then
rapidly increased in length, till experiments were discontinued after
October 5, on account of the number of people attracted to the field.
Although made on a ground open on every side, and bordered on two sides
by much-traveled thoroughfares, with electric cars passing every hour,
and seen by all the people living in the neighborhood for miles around,
and by several hundred others, yet these flights have been made by some
newspapers the subject of a great "mystery."
A practical flyer having been finally realized, we spent the years 1906
and 1907 in constructing new machines and in business negotiations. It
was not till May of this year that experiments (discontinued in October,
1905) were resumed at Kill Devil Hill, North Carolina. The recent
flights were made to test the ability of our machine to meet the
requirements of a contract with the United States Government to furnish
a flyer capable of carrying two men and sufficient fuel supplies for a
flight of 125 miles, with a speed of 40 miles an hour. The machine used
in these tests was the same one with which the flights were made at
Simms Station in 1905, though several changes had been made to meet
present requirements. The operator assumed a sitting position, instead
of lying prone, as in 1905, and a seat was added for a passenger. A
larger motor was installed, and radiators and gasoline reservoirs of
larger capacity replaced those previously used. No attempt was made to
make high or long flights.
In order to show the general reader the way in which the machine
operates, let us fancy ourselves ready for the start. The machine is
placed upon a single-rail track facing the wind, and is securely
fastened with a cable. The engine is put in motion, and the propellers
in the rear whir. You take your seat at the center of the machine beside
the operator. He slips the cable, and you shoot forward. An assistant
who has been holding the machine in balance on the rail starts forward
with you, but before you have gone 50 feet the speed is too great for
him, and he lets go. Before reaching the end of the track the operator
moves the front rudder, and the machine lifts from the rail like a kite
supported by the pressure of the air underneath it. The ground under you
is at first a perfect blur, but as you rise the objects become clearer.
At a height of 100 feet you feel hardly any motion at all, except for
the wind which strikes your face. If you did not take the precaution to
fasten your hat before starting, you have probably lost it by this
time. The operator moves a lever: the right wing rises, and the machine
swings about to the left. You make a very short turn, yet you do not
feel the sensation of being thrown from your seat, so often experienced
in automobile and railway travel. You find yourself facing toward the
point from which you started. The objects on the ground now seem to be
moving at much higher speed, though you perceive no change in the
pressure of the wind on your face. You know then that you are traveling
with the wind. When you near the starting-point the operator stops the
motor while still high in the air. The machine coasts down at an oblique
angle to the ground, and after sliding 50 or 100 feet, comes to rest.
Although the machine often lands when traveling at a speed of a mile a
minute, you feel no shock whatever, and cannot, in fact, tell the exact
moment at which it first touched the ground. The motor close beside you
kept up an almost deafening roar during the whole flight, yet in your
excitement you did not notice it till it stopped!
Our experiments have been conducted entirely at our own expense. In the
beginning we had no thought of recovering what we were expending, which
was not great, and was limited to what we could afford in recreation.
Later, when a successful flight had been made with a motor, we gave up
the business in which we were engaged, to devote our entire time and
capital to the development of a machine for practical uses. As soon as
our condition is such that constant attention to business is not
required, we expect to prepare for publication the results of our
laboratory experiments, which alone made an early solution of the flying
problem possible.
How We Made the First Flight
_By Orville Wright_
The flights of the 1902 glider had demonstrated the efficiency of our
system of maintaining equilibrium, and also the accuracy of the
laboratory work upon which the design of the glider was based. We then
felt that we were prepared to calculate in advance the performance of
machines with a degree of accuracy that had never been possible with the
data and tables possessed by our predecessors. Before leaving camp in
1902 we were already at work on the general design of a new machine
which we proposed to propel with a motor.
Immediately upon our return to Dayton, we wrote to a number of
automobile and motor builders, stating the purpose for which we desired
a motor, and asking whether they could furnish one that would develop
eight brake-horsepower, with a weight complete not exceeding 200 pounds.
Most of the companies answered that they were too busy with their
regular business to undertake the building of such a motor for us; but
one company replied that they had motors rated at 8 horse-power,
according to the French system of ratings, which weighed only 135
pounds, and that if we thought this motor would develop enough power for
our purpose they would be glad to sell us one. After an examination of
the particulars of this motor, from which we learned that it had but a
single cylinder of 4-inch bore and 5-inch stroke, we were afraid it was
much over-rated. Unless the motor would develop a full 8
brake-horsepower, it would be useless for our purpose.
Finally we decided to undertake the building of the motor ourselves. We
estimated that we could make one of four cylinders with 4-inch bore and
4-inch stroke, weighing not over two hundred pounds, including all
accessories. Our only experience up to that time in the building of
gasoline motors had been in the construction of an air-cooled motor,
5-inch bore and 7-inch stroke, which was used to run the machinery of
our small workshop. To be certain that four cylinders of the size we had
adopted (4" x 4") would develop the necessary 8 horse-power, we first
fitted them in a temporary frame of simple and cheap construction. In
just six weeks from the time the design was started, we had the motor on
the block testing its power. The ability to do this so quickly was
largely due to the enthusiastic and efficient services of Mr. C. E.
Taylor, who did all the machine work in our shop for the first as well
as the succeeding experimental machines. There was no provision for
lubricating either cylinders or bearings while this motor was running.
For that reason it was not possible to run it more than a minute or two
at a time. In these short tests the motor developed about nine
horse-power. We were then satisfied that, with proper lubrication and
better adjustments, a little more power could be expected. The
completion of the motor according to drawing was, therefore, proceeded
with at once.
[Illustration]
While Mr. Taylor was engaged with this work, Wilbur and I were busy in
completing the design of the machine itself. The preliminary tests of
the motor having convinced us that more than 8 horse-power would be
secured, we felt free to add enough weight to build a more substantial
machine than we had originally contemplated.
* * * * *
For two reasons we decided to use two propellers. In the first place we
could, by the use of two propellers, secure a reaction against a greater
quantity of air, and at the same time use a larger pitch angle than was
possible with one propeller; and in the second place by having the
propellers turn in opposite directions, the gyroscopic action of one
would neutralize that of the other. The method we adopted of driving the
propellers in opposite directions by means of chains is now too well
known to need description here. We decided to place the motor to one
side of the man, so that in case of a plunge headfirst, the motor could
not fall upon him. In our gliding experiments we had had a number of
experiences in which we had landed upon one wing, but the crushing of
the wing had absorbed the shock, so that we were not uneasy about the
motor in case of a landing of that kind. To provide against the machine
rolling over forward in landing, we designed skids like sled runners,
extending out in front of the main surfaces. Otherwise the general
construction and operation of the machine was to be similar to that of
the 1902 glider.
When the motor was completed and tested, we found that it would develop
16 horse-power for a few seconds, but that the power rapidly dropped
till, at the end of a minute, it was only 12 horse-power. Ignorant of
what a motor of this size ought to develop, we were greatly pleased with
its performance. More experience showed us that we did not get one-half
of the power we should have had.
With 12 horse-power at our command, we considered that we could permit
the weight of the machine with operator to rise to 750 or 800 pounds,
and still have as much surplus power as we had originally allowed for in
the first estimate of 550 pounds.
Before leaving for our camp at Kitty Hawk we tested the chain drive for
the propellers in our shop at Dayton, and found it satisfactory. We
found, however, that our first propeller shafts, which were constructed
of heavy gauge steel tubing, were not strong enough to stand the shocks
received from a gasoline motor with light fly wheel, although they would
have been able to transmit three or four times the power uniformly
applied. We therefore built a new set of shafts of heavier tubing, which
we tested and thought to be abundantly strong.
We left Dayton, September 23, and arrived at our camp at Kill Devil Hill
on Friday, the 25th. We found there provisions and tools, which had been
shipped by freight several weeks in advance. The building, erected in
1901 and enlarged in 1902, was found to have been blown by a storm from
its foundation posts a few months previously. While we were awaiting the
arrival of the shipment of machinery and parts from Dayton, we were busy
putting the old building in repair, and erecting a new building to serve
as a workshop for assembling and housing the new machine.
Just as the building was being completed, the parts and material for the
machines arrived simultaneously with one of the worst storms that had
visited Kitty Hawk in years. The storm came on suddenly, blowing 30 to
40 miles an hour. It increased during the night, and the next day was
blowing over 75 miles an hour. In order to save the tar-paper roof, we
decided it would be necessary to get out in this wind and nail down more
securely certain parts that were especially exposed. When I ascended the
ladder and reached the edge of the roof, the wind caught under my large
coat, blew it up around my head and bound my arms till I was perfectly
helpless. Wilbur came to my assistance and held down my coat while I
tried to drive the nails. But the wind was so strong I could not guide
the hammer and succeeded in striking my fingers as often as the nails.
The next three weeks were spent in setting the motor-machine together.
On days with more favorable winds we gained additional experience in
handling a flyer by gliding with the 1902 machine, which we had found in
pretty fair condition in the old building, where we had left it the year
before.
Mr. Chanute and Dr. Spratt, who had been guests in our camp in 1901 and
1902, spent some time with us, but neither one was able to remain to see
the test of the motor-machine, on account of the delays caused by
trouble which developed in the propeller shafts.
While Mr. Chanute was with us, a good deal of time was spent in
discussion of the mathematical calculations upon which we had based our
machine. He informed us that, in designing machinery, about 20 per cent.
was usually allowed for the loss in the transmission of power. As we had
allowed only 5 per cent., a figure we had arrived at by some crude
measurements of the friction of one of the chains when carrying only a
very light load, we were much alarmed. More than the whole surplus in
power allowed in our calculations would, according to Mr. Chanute's
estimate, be consumed in friction in the driving chains. After Mr.
Chanute's departure, we suspended one of the drive chains over a
sprocket, hanging bags of sand on either side of the sprocket of a
weight approximately equal to the pull that would be exerted on the
chains when driving the propellers. By measuring the extra amount of
weight needed on one side to lift the weight on the other, we calculated
the loss in transmission. This indicated that the loss of power from
this source would be only 5 per cent., as we originally estimated. But
while we could see no serious error in this method of determining the
loss, we were very uneasy until we had a chance to run the propellers
with the motor to see whether we could get the estimated number of
turns.
The first run of the motor on the machine developed a flaw in one of the
propeller shafts which had not been discovered in the test at Dayton.
The shafts were sent at once to Dayton for repair, and were not received
again until November 20, having been gone two weeks. We immediately put
them in the machine and made another test. A new trouble developed. The
sprockets which were screwed on the shafts, and locked with nuts of
opposite thread, persisted in coming loose. After many futile attempts
to get them fast, we had to give it up for that day, and went to bed
much discouraged. However, after a night's rest, we got up the next
morning in better spirits and resolved to try again.
While in the bicycle business we had become well acquainted with the use
of hard tire cement for fastening tires on the rims. We had once used it
successfully in repairing a stop watch after several watchsmiths had
told us it could not be repaired. If tire cement was good for fastening
the hands on a stop watch, why should it not be good for fastening the
sprockets on the propeller shaft of a flying machine? We decided to try
it. We heated the shafts and sprockets, melted cement into the threads,
and screwed them together again. This trouble was over. The sprockets
stayed fast.
Just as the machine was ready for test bad weather set in. It had been
disagreeably cold for several weeks, so cold that we could scarcely work
on the machine for some days. But now we began to have rain and snow,
and a wind of 25 to 30 miles blew for several days from the north. While
we were being delayed by the weather we arranged a mechanism to measure
automatically the duration of a flight from the time the machine started
to move forward to the time it stopped, the distance traveled through
the air in that time, and the number of revolutions made by the motor
and propeller. A stop watch took the time; an anemometer measured the
air traveled through; and a counter took the number of revolutions made
by the propellers. The watch, anemometer and revolution counter were all
automatically started and stopped simultaneously. From data thus
obtained we expected to prove or disprove the accuracy of our propeller
calculations.
On November 28, while giving the motor a run indoors, we thought we
again saw something wrong with one of the propeller shafts. On stopping
the motor we discovered that one of the tubular shafts had cracked!
[Illustration]
Immediate preparation was made for returning to Dayton to build another
set of shafts. We decided to abandon the use of tubes, as they did not
afford enough spring to take up the shocks of premature or missed
explosions of the motor. Solid tool-steel shafts of smaller diameter
than the tubes previously used were decided upon. These would allow a
certain amount of spring. The tubular shafts were many times stronger
than would have been necessary to transmit the power of our motor if the
strains upon them had been uniform. But the large hollow shafts had no
spring in them to absorb the unequal strains.
Wilbur remained in camp while I went to get the new shafts. I did not
get back to camp again till Friday, the 11th of December. Saturday
afternoon the machine was again ready for trial, but the wind was so
light a start could not have been made from level ground with the run of
only sixty feet permitted by our monorail track. Nor was there enough
time before dark to take the machine to one of the hills, where, by
placing the track on a steep incline, sufficient speed could be secured
for starting in calm air.
Monday, December 14, was a beautiful day, but there was not enough wind
to enable a start to be made from the level ground about camp. We
therefore decided to attempt a flight from the side of the big Kill
Devil Hill. We had arranged with the members of the Kill Devil Hill Life
Saving Station, which was located a little over a mile from our camp, to
inform them when we were ready to make the first trial of the machine.
We were soon joined by J. T. Daniels, Robert Westcott, Thomas Beachem,
W. S. Dough and Uncle Benny O'Neal, of the station, who helped us get
the machine to the hill, a quarter mile away. We laid the track 150 feet
up the side of the hill on a 9-degree slope. With the slope of the
track, the thrust of the propellers and the machine starting directly
into the wind, we did not anticipate any trouble in getting up flying
speed on the 60-foot monorail track. But we did not feel certain the
operator could keep the machine balanced on the track.
When the machine had been fastened with a wire to the track, so that it
could not start until released by the operator, and the motor had been
run to make sure that it was in condition, we tossed up a coin to decide
who should have the first trial. Wilbur won. I took a position at one of
the wings, intending to help balance the machine as it ran down the
track. But when the restraining wire was slipped, the machine started
off so quickly I could stay with it only a few feet. After a 35 to
40-foot run it lifted from the rail. But it was allowed to turn up too
much. It climbed a few feet, stalled, and then settled to the ground
near the foot of the hill, 105 feet below. My stop watch showed that it
had been in the air just 3-1/2 seconds. In landing the left wing touched
first. The machine swung around, dug the skids into the sand and broke
one of them. Several other parts were also broken, but the damage to the
machine was not serious. While the test had shown nothing as to whether
the power of the motor was sufficient to keep the machine up, since the
landing was made many feet below the starting point, the experiment had
demonstrated that the method adopted for launching the machine was a
safe and practical one. On the whole, we were much pleased.
Two days were consumed in making repairs, and the machine was not ready
again till late in the afternoon of the 16th. While we had it out on the
track in front of the building, making the final adjustments, a stranger
came along. After looking at the machine a few seconds he inquired what
it was. When we told him it was a flying machine he asked whether we
intended to fly it. We said we did, as soon as we had a suitable wind.
He looked at it several minutes longer and then, wishing to be
courteous, remarked that it looked as if it would fly, if it had a
"suitable wind." We were much amused, for, no doubt, he had in mind the
recent 75-mile gale when he repeated our words, "a suitable wind!"
During the night of December 16, 1903, a strong cold wind blew from the
north. When we arose on the morning of the 17th, the puddles of water,
which had been standing about camp since the recent rains, were covered
with ice. The wind had a velocity of 10 to 12 meters per second (22 to
27 miles an hour). We thought it would die down before long, and so
remained indoors the early part of the morning. But when ten o'clock
arrived, and the wind was as brisk as ever, we decided that we had
better get the machine out and attempt a flight. We hung out the signal
for the men of the life saving station. We thought that by facing the
flyer into a strong wind, there ought to be no trouble in launching it
from the level ground about camp. We realized the difficulties of flying
in so high a wind, but estimated that the added dangers in flight would
be partly compensated for by the slower speed in landing.
We laid the track on a smooth stretch of ground about one hundred feet
north of the new building. The biting cold wind made work difficult, and
we had to warm up frequently in our living room, where we had a good
fire in an improvised stove made of a large carbide can. By the time all
was ready, J. T. Daniels, W. S. Dough and A. D. Etheridge, members of
the Kill Devil Life Saving Station; W. C. Brinkley, of Manteo, and
Johnny Moore, a boy from Nag's Head, had arrived.
We had a "Richards" hand anemometer with which we measured the velocity
of the wind. Measurements made just before starting the first flight
showed velocities of 11 to 12 meters per second, or 24 to 27 miles per
hour. Measurements made just before the last flight gave between 9 and
10 meters per second. One made just after showed a little over 8 meters.
The records of the Government Weather Bureau at Kitty Hawk gave the
velocity of the wind between the hours of 10:30 and 12 o'clock, the time
during which the four flights were made, as averaging 27 miles at the
time of the first flight and 24 miles at the time of the last.
* * * * *
Wilbur, having used his turn in the unsuccessful attempt on the 14th,
the right to the first trial now belonged to me. After running the motor
a few minutes to heat it up, I released the wire that held the machine
to the track, and the machine started forward into the wind. Wilbur ran
at the side of the machine, holding the wing to balance it on the track.
Unlike the start on the 14th, made in a calm, the machine, facing a
27-mile wind, started very slowly. Wilbur was able to stay with it till
it lifted from the track after a forty-foot run. One of the life saving
men snapped the camera for us, taking a picture just as the machine had
reached the end of the track and had risen to a height of about two
feet. The slow forward speed of the machine over the ground is clearly
shown in the picture by Wilbur's attitude. He stayed along beside the
machine without any effort.
The course of the flight up and down was exceedingly erratic, partly due
to the irregularity of the air, and partly to lack of experience in
handling this machine. The control of the front rudder was difficult on
account of its being balanced too near the center. This gave it a
tendency to turn itself when started; so that it turned too far on one
side and then too far on the other. As a result the machine would rise
suddenly to about ten feet, and then as suddenly dart for the ground. A
sudden dart when a little over a hundred feet from the end of the track,
or a little over 120 feet from the point at which it rose into the air,
ended the flight. As the velocity of the wind was over 35 feet per
second and the speed of the machine against this wind ten feet per
second, the speed of the machine relative to the air was over 45 feet
per second, and the length of the flight was equivalent to a flight of
540 feet made in calm air. This flight lasted only 12 seconds, but it
was nevertheless the first in the history of the world in which a
machine carrying a man had raised itself by its own power into the air
in full flight, had sailed forward without reduction of speed, and had
finally landed at a point as high as that from which it started.
* * * * *
At twenty minutes after eleven Wilbur started on the second flight. The
course of this flight was much like that of the first, very much up and
down. The speed over the ground was somewhat faster than that of the
first flight, due to the lesser wind. The duration of the flight was
less than a second longer than the first, but the distance covered was
about seventy-five feet greater.
Twenty minutes later the third flight started. This one was steadier
than the first one an hour before. I was proceeding along pretty well
when a sudden gust from the right lifted the machine up twelve to
fifteen feet and turned it up sidewise in an alarming manner. It began
sliding off to the left. I warped the wings to try to recover the
lateral balance and at the same time pointed the machine down to reach
the ground as quickly as possible. The lateral control was more
effective than I had imagined and before I reached the ground the right
wing was lower than the left and struck first. The time of this flight
was fifteen seconds and the distance over the ground a little over 200
feet.