the bicycle shop, to tell Orville enthusiastically of an idea he had
hit upon. A customer had dropped in to buy an inner tube for a tire.
Wilbur had taken the tube from the pasteboard box it came in and was
toying with the box while talking to the customer. As he twisted the
box he observed that though the vertical sides were rigid endwise, the
top and bottom sides could be twisted to have different angles at the
opposite ends. Why, he thought, couldn’t the wings of a gliding machine
be warped from one end to the other in this same way? Thus the wings
could be put at a greater angle at one side than at the other, without
structural weakness. That plan seemed so satisfactory that the Wrights
did not look for or consider any other method.
A few weeks later, in August, 1899, the brothers built a biplane kite,
and Wilbur, with a group of small boys as spectators, flew it on a
common at the edge of town. This kite had wing surfaces five feet from
tip to tip by thirteen inches wide. The warping of these surfaces
could be accomplished by the use of four cords reaching from the kite
to the ground. Two of the cords were attached to the forward corners
of the right wing tips, one to the upper and one to the lower; the
other ends of the cords, at the ground, were tied to opposite ends of
a short stick to be held in the operator’s hand. The cords tied to the
left wing were arranged in the same way. With a stick in each hand,
the operator could move the wings as he desired. The upper wing could
be moved farther forward or farther backward than the lower wing,
according to the direction in which the two sticks were simultaneously
inclined, by movement of the wrists. By inclining the two sticks in
opposite directions it was possible to draw one upper wing tip farther
forward than the lower at that end, while at the other end of the kite
the lower wing tip would be the one farther forward. This moving of
the wing tips in opposite directions caused a twisting or warping of
the wings. Then the wing at one end would be presented to the wind at
a different angle from that at the other end. If one end of the kite
started to sink, sidewise balance could be restored by exposing the
wing at that end at a greater angle, thus getting more lift.
Balance from front to rear was to be maintained by inclining the two
sticks in the operator’s hands in the same direction--to move the upper
wing either forward or backward over the lower wing, to change the
center of lift.
But in addition to this moving of the wings forward and backward, the
Wrights added an “elevator” at the rear. It was held by a pair of
wooden rods attached at right angles to the uprights that connected the
wings. When the upper wing was pulled forward, to turn the kite upward
in front, the elevator met the air at its top side and was pressed
downward, which helped to turn the wings upward--as the rear elevator
does on planes today.
Though their interest did not lag, the Wrights did nothing more for
some time about kite experiments, except to seek information in regard
to wind velocity in different parts of the country. They wrote to the
Weather Bureau at Washington, in December, 1899, and Willis Moore,
chief of that Bureau, sent them a number of government bulletins that
included statistics on wind velocities at various places. They looked
these over, but at that time made no further investigation of any of
the places mentioned.
[Illustration: THE FIRST CAMP AT KITTY HAWK. _Top_: The 1900 camp.
_Bottom_: Kitty Hawk Bay as seen from the 1900 camp.]
In May, 1900, Wilbur Wright wrote a letter to Octave Chanute, living in
Chicago, who had written _Progress in Flying Machines_. Though Chanute
was better known in engineering circles by his work for certain western
railroads, as well as for having built the Kansas City bridge and the
Chicago stockyards, his book, a reprint of his articles published from
1891 to 1893, had made him probably the best authority on the history
of aeronautics. Thinking Chanute would be interested, Wilbur told him
in his letter of a plan he had for experimenting with a man-carrying
kite by means of which, Wilbur thought, one would be able to get hours
of practice in operating a machine in the air. He proposed the use of a
high tower from the top of which a cable would lead to the man-carrying
kite. He described to Chanute, in his letter, the system of control to
be used in the kite--the warping of wings for lateral control, and the
shifting of the upper surface backward and forward for longitudinal
control--the same system used in the five-foot kite tested the previous
August. Then he asked Chanute if he had any information as to locations
where winds suitable for carrying on such experiments might be found.
(This letter from Wilbur marked the beginning of an acquaintance and
correspondence with Chanute that lasted for a number of years.) Chanute
suggested San Diego, California, and St. James City (Pine Island),
Florida, to be considered because of the steady sea breezes. But, on
the other hand, he pointed out that, since those places were deficient
in sand hills, perhaps even better locations could be found on the
Atlantic coast of South Carolina or Georgia.
[Illustration: THE 1902 GLIDER. The Wrights are testing the efficiency
of the 1902 glider by flying it as a kite--September 19, 1902.]
When the rush of the spring trade in bicycles began to subside,
giving them more time for other interests, the Wrights again took
up with enthusiasm the study of equilibrium. Each day they proposed
and discussed new devices. Orville thought the shifting of the upper
surface backward and forward over the lower one, for longitudinal
equilibrium, though successful in their kite, would not be practical
for a man-carrying glider, which would start and land on the ground.
He suggested that the wing surfaces be fixed one above the other, and
that an elevator be placed some distance in front of the wings, instead
of at the rear. In this position there would be less danger of the
elevator touching the ground in starting; and if from any cause the
elevator were disabled it would be discovered before the machine got
into the air. Wilbur then proposed that, since curved surfaces were
more efficient than flat planes, the front rudder, or elevator, should
be made flexible. Then it could be bent to present a concave surface on
whichever side a pressure was desired, but would be flat when moving
edgewise through the air.
The Wrights did not at first think an elevator in front would provide
inherent stability--that is, it would not give the machine the desired
tendency to restore its own balance just from the arrangement of its
fixed parts. But Wilbur shortly afterward developed a theory that led
him to believe the machine would have that quality.
Having read that the center of pressure moves toward the front edge
of the wings whenever the wings are turned more nearly horizontal in
flight, he thought inherent longitudinal stability could be obtained
if the front elevator were set at a negative angle--that is, with its
front edge lower than its rear edge. With such an arrangement of wings
and elevator, every time the wings became more nearly horizontal in
flight and met the air at a smaller angle on their under sides, the
elevator would meet the air at a greater angle on its upper side. So,
he reasoned, whenever, by becoming more nearly horizontal, the wings
caused the center of pressure to move forward, tending to turn the
machine upward in front, the front elevator would receive a greater
downward pressure on its upper side and so counteract the disturbing
pressure on the wings.
Actual tests later proved that the negative angle of the front elevator
did not provide the inherent stability expected. The explanation was
that the center of pressure on cambered wings traveled in the opposite
direction from that which Wilbur’s reading had led him to expect. The
Wrights later were to discover that Wilbur’s reasoning was correct;
but because the travel of the center of pressure was rearward instead
of forward the elevator had to be set at a positive instead of at a
negative angle.
The Wrights’ elevator possessed three features not found in the gliders
of any of the earlier experimenters. It was in front of the wings,
where it was less liable to damage by striking the ground in take-off
and landing; it was operable, instead of fixed as in other machines;
and it flexed to present a convex surface to the air, instead of a flat
surface. At this early stage of their work the Wrights considered this
front elevator their most important invention, because, from their
reading, they thought it was solving a problem more difficult than that
of lateral control.
Though the Wrights’ reasons for placing the elevator in front of the
wings were at first those just mentioned, they afterward found that
this arrangement had much greater importance for two reasons not at
first discovered. One of these was that it eliminated all danger of a
nose dive when the plane got into what is known as a “stall”--when the
speed became too slow. The other reason was that the elevator in front,
set at a positive angle with the pressure on its under side, not only
produced inherent stability, but also carried part of the load, and so
relieved the wings to that extent. (An elevator in the rear, set at a
negative angle to provide inherent stability, carries a pressure on its
upper side, which adds just that much to the load the wings must carry.)
Around the first of August, 1900, the brothers decided to build a
man-carrying glider on which to try out their inventions. To get
practice in operating it they would first fly it as a kite. For such
kite flying, flat open country would be needed; and for the gliding,
sand hills free from trees or shrubs. Once again they examined the
reports they had received from the Weather Bureau at Washington.
Several of the places where winds might be suitable were in the Far
West, but one in the East, much nearer to Dayton, was a place with an
odd name, Kitty Hawk, North Carolina. They decided to write at once to
Kitty Hawk for further information.
Wilbur Wright addressed a letter to the chief of the Kitty Hawk
weather bureau station, asking for various details about the locality,
explaining that he might wish to go there shortly to conduct
experiments with a man-carrying kite. He inquired, too, if it would be
possible for him and his brother to obtain board and lodging in the
vicinity until they could get themselves established in a camp.
Joseph J. Dosher, in charge of the Kitty Hawk station, who received
the letter, replied briefly, on August 16, giving the direction of the
prevailing winds; and he described the nature of the land for many
miles.
After writing his reply, Dosher handed Wilbur Wright’s letter to
a neighbor, William J. Tate, with the request that he also make a
reply. “Bill” Tate (later known as Captain Tate) was probably the
best-educated man in that locality. He lived about a mile inland from
the weather station, in the hamlet or settlement of Kitty Hawk, where
he had formerly been the postmaster. For all practical purposes he
still was the postmaster, though the office was in his wife’s name.
Endowed with a gift for expressing himself readily in either speech
or writing, Tate did a creditable job when he wrote to Wilbur Wright
on August 18. Not only did he tell about the suitability of the Kitty
Hawk region, because of the prevailing high winds, for the kind of
experiments Wilbur had mentioned, but he went into details about the
treeless sand hills and the general terrain. And he said arrangements
could undoubtedly be made for the Wrights to obtain board for as long
as desired.
The letters from Dosher and Tate--particularly the one from
Tate--convinced the Wrights that Kitty Hawk was the place for their
experiments. Almost immediately they decided they would go to Kitty
Hawk as soon as they could build their glider.
The work at Dayton, getting parts and material ready for the glider,
required only a few weeks. Only the cutting and sewing of the cloth
covering for the wings, the bending of the ash ribs into shape, and
making the metal connections, took much time. The cost of the whole
machine in actual money outlay was trifling, probably not more than $15.
It was arranged that Orville should stay in Dayton, to look after the
bicycle shop until Wilbur got settled at Kitty Hawk, and then join him
there.
Wilbur set out on a September day, taking with him parts of the glider
and all material needed to assemble it except some spruce lumber he
expected to obtain nearer his destination.
The journey proved to be more of an undertaking than Wilbur expected.
V
GLIDING AT KITTY HAWK
One must look at a map of North Carolina to get an idea of the
isolation of the long strip of sandy beach that separates the Atlantic
Ocean from Albemarle, Pamlico, and Roanoke Sounds. At the time the
Wrights went there, no bridges connected this beach with any part of
the North Carolina mainland or even with near-by Roanoke Island, seat
of Sir Walter Raleigh’s “Lost Colony.” At one point on the beach was
the Kitty Hawk life-saving station, and alongside of it a government
weather bureau. About a mile back from the ocean was the hamlet of
Kitty Hawk which, though it had a post office, was little more than a
settlement, with only about a score of dwelling houses, most of them as
widely scattered as in an ordinary farming community. Four miles south
was the Kill Devil life-saving station.
It was not surprising that when Wilbur Wright, on September 9, 1900,
reached Elizabeth City, North Carolina, the nearest railroad point
to his destination, the first persons he chanced to ask about Kitty
Hawk had never heard of the place. Then he learned that a boat made
weekly trips to Roanoke Island; but it had gone the day before. Not
liking delay, he went to the water front to inquire if another boat
might be available. There he met one Israel Perry, formerly a resident
of Kitty Hawk, who lived the year round on his little flat-bottomed
schooner. As no other boatman showed any interest in making the trip,
Wilbur booked passage with “Captain” Perry, despite the boat’s dirty,
forbidding appearance. After loading parts of the glider and other
goods that had been shipped from Dayton, he set out with Perry on the
morning of September 10 for the forty-mile voyage to Kitty Hawk. Wilbur
noticed that the small boat they used to go from the wharf out to where
the schooner was anchored was leaking badly and he asked if it was safe.
“Oh,” Perry assured him, “it’s safer than the _big_ boat.” That didn’t
inspire too much confidence in what was in store, and Wilbur soon
learned that any misgivings he felt were amply justified. Toward the
middle of the afternoon they met a strong head wind that forced them to
seek a smooth water haven in North River where they anchored to await
better weather. By that time Wilbur had worked up a good appetite; but
he discovered that neither the food nor the kitchen met even minimum
standards of cleanliness and he made excuses, as politely as he could,
for not eating. All he had with him against hunger was a small jar of
jelly his sister Katharine had slipped into his suitcase.
The weather was not favorable for continuing the voyage until the
afternoon of the second day, and the boat reached a wharf, where there
was a small store, on Kitty Hawk bay, at about nine o’clock that night.
Not knowing where else to go, Wilbur stayed aboard until the next
morning. A small boy named Baum agreed to guide him to the home of
William J. Tate, about a quarter of a mile away. By the time Wilbur
arrived there, on that morning of September 12, it was just forty-eight
hours since he had tasted food other than his little supply of jelly.
After introducing himself, and in response to “Bill” Tate’s inquiries
about how he enjoyed his trip, Wilbur spoke of his back being sore from
lying on deck and of how his arm ached from holding on when the boat
rolled. Then it came out that he had been unable to bring himself to
eat the food provided on the Perry schooner.
“You mean to tell me,” asked “Bill” Tate, greatly concerned, “that
you’ve eaten no victuals for two days?”
Here was a situation that called for quick action in a hospitable home.
It was after the Tates’ breakfast hour, but Mrs. Tate soon had a fire
in the kitchen stove and prepared a great platter of ham and eggs that
the guest seemed to relish.
Then Wilbur inquired if it would be possible for him to obtain board
and lodging there for the week or more until his brother “Orv” arrived.
Tate went into an adjoining room to ask his wife. As the door was ajar,
Wilbur could hear what was said. Mrs. Tate was a bit alarmed. Here
was a man able to devote time and money for weeks at a time to sport.
Doubtless he must be a person of great wealth, accustomed to every
luxury. Would he be satisfied with the best they could offer?
Wilbur stepped to the door, explaining that he could not help
overhearing their conversation, and said it must be understood that
if he were accepted as a paying guest he would not expect any extra
frills, but would greatly appreciate the courtesy.
“This fellow’s a real gentleman,” thought Tate, and by way of settling
the question, without waiting to hear any more from his wife, he said
to Wilbur:
“You must be tired. Why don’t you come into our spare bedroom and take
a nap?”
By the next day Wilbur was at work. The cloth covering for the
glider--white French sateen of extra good quality--had already been
shaped and sewed at Dayton, except at the ends, to permit fitting it
over the framework. But now he had to make changes in the covering,
because the glider was going to be smaller than originally planned. The
longest timbers, for the wing spars, that he had been able to find in
either Norfolk or Elizabeth City were only sixteen feet long instead
of the eighteen-foot length he desired. Thus it was necessary to cut
out strips from the middle of the lengths of cloth for both upper and
lower wings. For resewing the cloth where necessary, Wilbur borrowed
Mrs. Tate’s machine. But all the rest of the work of assembling the
glider was done at a tent Wilbur set up, about half a mile from the
Tate home, at a spot where there were a few trees and a view of the
bay. He dragged the crates, containing various parts and tools, to the
tent and hoped to have everything in readiness when Orville arrived.
But the heat was intense, the job of carrying water to the camp used up
much energy, and when Orville got there, on September 28, Wilbur told
him regretfully that much work on the glider was still to be done.
Orville’s trip had been uneventful. Indeed, though he came on a better
boat than Israel Perry’s, he had struck such a calm sea that his voyage
from Elizabeth City took two days, the same as Wilbur’s. For the
first five days after Orville’s arrival, both brothers stayed at the
Tate home. Then they established themselves in camp. One end of their
tent, twelve by twenty-two feet, was tied to a tree for anchorage. The
tree was headquarters for a mocking bird that sometimes joined in the
harmony when Orville twanged at a mandolin he had brought from home.
Not many visitors came to the camp from near-by Kitty Hawk. One reason
for this was that the camp was considered dangerous after news got
about that the Wrights used a gasoline stove. “Bill” Tate was favorably
impressed, though, with an acetylene lamp, intended for a bicycle, that
the Wrights used for lighting. He said he had a notion to install such
a system of gas lighting in his house.
It was necessary to carry water about one thousand feet over the sand.
Orville volunteered to do the cooking--and he continued to do so during
all their experiments at Kitty Hawk. But he always felt that he had the
better of the bargain, for the dish-washing job was Wilbur’s. As it was
impossible to obtain fresh bread, Orville learned to make biscuits,
and without use of milk. They were good biscuits, too--better, his
father afterward insisted, than anyone else could make. To simplify
operations, Orville always mixed at one time enough flour and other dry
ingredients to last for several days, as biscuits had to be baked three
times daily.
Working together, the brothers soon had the glider assembled. When
completed it weighed about fifty-two pounds. Though the main spars were
only sixteen feet long, the “bows” at the ends of each wing surface
brought the total span to nearly seventeen and one-half feet. The
total lifting area was 165 square feet instead of 200 as intended. A
space eighteen inches wide at the center of the lower surface where
the operator would lie, with feet over the rear spar, was left free of
covering. The apparatus had no rear vanes or tail of any kind; but it
had two important features never used by previous experimenters. One
was the front rudder, or “elevator,” the rear edge of which was about
thirty inches from the nearest edge of the wings; the other was the
wing warping. By an ingenious arrangement of the trussing, the wings
could be twisted into a helicoidal warp from one end to the other, thus
exposing one wing to the air at a greater angle than the other. This
was to be used for bringing the machine back to the level after it was
tipped up sidewise by a gust of wind.
The Wrights’ first surprise at Kitty Hawk was that the winds there were
not what they had counted on. United States Weather Bureau reports
had led them to think they would have winds of about fifteen miles an
hour almost every day. But now it dawned on them that fifteen miles an
hour was simply the daily average for a month. Sometimes the wind was
sixty miles an hour, and the next day it would be entirely calm. It now
began to look as if they might frequently have to wait a few days for
suitable conditions, which meant that their experiments would require
more time than they had expected.
Almost as soon as they began their trials of the glider, the brothers
got another surprise. According to the Lilienthal tables of air
pressures, their machine of 165 square feet needed a wind of only from
seventeen to twenty-one miles an hour to support it as a kite with a
pilot aboard. But they found that much stronger winds were needed to
lift it. Since suitable winds would not be plentiful, their plan of
practicing by the hour aboard the glider while flying it as a kite
would have to be postponed. Instead, they flew it as a kite, loaded
with about fifty pounds of chain, but with no man aboard. They held it
with two ropes, and operated the balancing system by cords from the
ground. Though the results were promising, inspiring confidence in
the system of maintaining equilibrium, the brothers knew that only by
actual gliding experience could they confirm what the kite experiments
had indicated as being true.
One thing that puzzled them was that the machine appeared to be greatly
deficient in lifting power as compared with calculated lift of curved
surfaces of its size. In wondering what might be the cause of this wide
discrepancy between expected and actual lifts, the Wrights considered
the possibility that it might be because the curvature of the wings
was less than that used by Lilienthal. Or could it be that the cloth
covering was too porous and permitted some of the lifting power of the
wind to be lost? They wondered, too, if the Lilienthal tables they had
followed, relating to air pressure on wing surfaces, could be in error.
They next determined to try gliding on the side of a hill. That meant
toting their machine four miles south of their camp to a great sand
dune about one hundred feet high, called Kill Devil Hill. On their
first day at the hill, the wind was about twenty-five miles an hour.
As they lacked previous experience at gliding they decided to wait
for less of a blow for their first attempt. The next day the wind had
subsided to fourteen miles an hour, and they made about a dozen glides.
“Bill” Tate was there and assisted them.
In making these glides, the machine was usually only two or three feet
from the soft, sandy ground, and though the brothers repeatedly made
landings while moving at a speed of twenty miles an hour, neither
operator nor machine was harmed. The slope of the hill toward the
northeast was about 9½ degrees, or a drop of approximately one foot
in six. After moving at a rate of about twenty-five to thirty miles
an hour with reference to the wind, or ten to fifteen miles over the
ground, the machine, while keeping its course parallel to the slope,
increased its speed, thus indicating that it could glide on a slope
less steep.