Wright Brothers – The Kitty Hawk Years

Articles relating to the years the Wright Brothers spent at Kitty Hawk.

Before the Wright Brothers, all other attempts to fly were failures. In 1896, the death of the famous German glider pilot Otto Lilienthal, victim of a glider accident, discouraged further attempts to fly by the Europeans. The death of Lilienthal after six successive years of experiments involving 2,000 glides, had the opposite effect on the Wrights. It strengthened their resolve to find the solution.

Defining The Problem

They began by studying the available literature. They found no books on the subject of aeronautics in the Dayton Library. At the time, aeronautics was a discredited subject and consequently the libraries did not ordinarily carry books on that subject.

They wrote and received material from the Smithsonian Institution and from Octave Chanute. Chanute, author of “Progress in Flying Machines,” was an internationally respected Chicago aeronautic historian and experimenter. Wilbur wrote to Chanute and an extraordinary collaboration resulted that included 435 letters that continued until Chanute’s death in 1910

From Lilienthal they were reinforced in their idea to learn to fly gliders before advancing to powered machines and the use of cambered wings. They also used the aerodynamic coefficients that were developed by Lilienthal in their design calculations for their gliders.

On the whole, Wilbur was not impressed with the information he found. The main thing he learned was the mistakes that others had made. He concluded that the problem of flight was so vast and many-sided that no one could hope to win unless possessed with the unusual ability to grasp the essential points and to ignore the nonessentials.

Orville and Wilbur, unlike the others, who kept doing the same things and got the same unsatisfactory results, identified the essential issues of flight were lift and control, but especially control – the ability to balance and steer the machine in flight.

Wilbur wrote to Octave Chanute, “My observation of the flight of buzzards leads me to believe that they regain their lateral balance when partly overturned by a gust of wind, by a torsion of the tips of the wings.”

To test his theory, in 1899, he built and flew a 5-foot biplane box kite at Ahlers Park not far from his home in Dayton. Wilbur rigged the kite with four cords that were arranged so that he could exercise control of flight by twisting the wing tips of the kite simultaneously in opposite directions, a process Chanute named as wing warping.

It worked! It would enable the Wrights to build the ability to control a flying machine into the machine itself.

Selection of Kitty Hawk

By 1900, the Wrights had progressed sufficiently in their engineering analysis of the mystery of flying that they were ready to conduct real life experiments using gliders.

Their 5-foot kite had worked, but they were not sure that it would work with a scaled-up glider. They remembered that a scaled-up version of a toy helicopter they made as children, did not work.

They designed a glider with a forward elevator (canard) and used the latest data available on the appropriate camber shape for the wings. The glider had a wingspan of 17-feet, 5-inches and weighed 52 pounds. It cost $15. Now they needed a place to experiment with the glider.

They wanted a location that provided privacy, sufficient wind for lift, and sand for soft landings. The latter was important because many others had died in their attempts at flying. A popular saying at the time was: “There are old pilots and bold pilots, but there are no old and bold pilots.”

It is a good thing they considered safety because in hindsight their glider had many problems and was dangerous to fly.

They considered a number of locations such as California, Florida and South Carolina. Kitty Hawk was in sixth place on the list of windy locations provided by the weather bureau. What drew them to the little fishing village of Kitty Hawk, North Carolina was Bill Tate.

Bill, 40 years old, was a Currituck County commissioner, notary public and the assistant postmaster of Kitty Hawk. He also was the best-educated citizen of Kitty Hawk, a town with a population of about 60. He found out about the Wrights when Wilbur wrote to the government weather station on Kitty Hawk on August 3, 1900 inquiring about weather conditions.

Somehow the letter was transferred to Tate to answer. Tate, who was interested in promoting this remote area, wrote the Wrights that Kitty Hawk offered excellent conditions for their experiments, “including a sandy beach with a bare hill in the center 80 feet high with no trees or bushes to obstruct the wind.” As further inducement, he offered his family’s hospitality.

The Wrights accepted the invitation and as it turned out, the Tate family was a big help. Bill and his half brother, Dan, assisted with the experiments and even Dan’s 9-year old son occasionally served as ballast on the glider. Orville used Bill Tate’s wife’s sewing machine to sew the French sateen fabric on the wings.

Wilbur wrote to his father, “It is my belief that flight is possible and, while I am taking up the investigation for pleasure rather than profit, I think there is a slight possibility of achieving fame and fortune from it.”

The Dangerous Trip

The technical problems of flying weren’t the only problems that Orville and Wilbur Wright had to overcome. Getting themselves and their equipment from Dayton, Ohio, to Kitty Hawk was difficult and dangerous. Wilbur almost drowned in a storm in Albermarle Sound on this first trip in 1900.

On September 6, 1900, Wilbur left Dayton by train headed for Kitty Hawk for the first of what became four annual trips. Orville would follow later with the camping equipment. Wilbur had with him the disassembled glider and all the tools needed for the experiments, except for the long spruce spars used in the wings. He planned to buy those in Norfolk, Virginia.

He arrived in Old Point Comfort, Virginia and a day later took the ferry to Norfolk. The next day he tried to buy the spruce wing spars but had to settle for white pine that were two feet shorter than the planned eighteen-foot length. As a result, this required an unplanned design modification to the wings upon arrival at Kitty Hawk. That change reduced the area of the wings and consequently the effectiveness of their “lift” experiments.

The day in Norfolk was an unseasonably hot 100 degrees. Wilbur, always properly dressed in a suit and wearing a starched collar, almost had a heat stroke. However, the greatest obstacle to his health was yet to come.

In those days there were no bridges to Kitty Hawk. The usual way people ventured to Kitty Hawk was by a small sailboat from Manteo, Roanoke Island, NC. Manteo is located 50 miles from Elizabeth City.

Wilbur was impatient and decided to take a shortcut, bypassing Manteo. Arriving in Elizabeth City, he decided to rent a boat to take him directly to Kitty Hawk.

He was able to secure passage on a schooner owned by Israel Perry, a resident of Kitty Hawk. Perry’s schooner was anchored several miles away and could be reached only by a flat-bottomed fishing boat that Perry lived on.

Wilbur set out on the fishing boat with a trunk and the 16-foot wing spars. There wasn’t room for the crates that held the dissembled glider so he left them behind in storage to be forwarded later by a freight boat.

The fishing boat rode low in the water and it wasn’t long before all hands, including Wilbur, had to bail water to keep the boat afloat. In this manner they reached Perry’s schooner, the Curlicue. Any feeling of relief the party may have had wouldn’t last long.

The worst was yet to come.

The Curlicue set sail down the Pasquotank River into Albemarle Sound about nightfall. Shortly thereafter, with little warning, a storm struck. The Curlicue began to violently roll in the waves and sprung an ominous leak. Once again everyone had to bail water.

The schooner couldn’t be turned around because of the danger of being swamped, so they headed into the wind and managed to go back up around the tip of Camden Point. In the process, the foresail blew loose and Wilbur was pressed into service to help take it down. Then the mainsail tore loose and caused the stern to swing around to the wind, allowing waves to break over the stern.

Fortunately, the schooner made relative safety of the North River by reaching a sandbar with only the jib taking the wind. Disaster was prevented. They rode out the rest of the storm at anchor. A drenched Wilbur spent the night on the deck trying to sleep.

The next day the weather cleared and the Curlicue set sail again for Kitty Hawk, arriving that night at the wharf. It was dark when they arrived. Not knowing the way, Wilbur spent another night sleeping on the deck.

The next morning Wilbur arrived at the Tate house famished, exhausted and bedraggled. He hadn’t eaten anything in the past 48 hours but some jelly his sister, Katharine, had packed for him.

A young neighbor boy, Elijah Baum, showed Wilbur the way to the house. When Tate answered the door, Wilbur took off his cap and introduced himself as the man “to whom you wrote concerning this section.” His arrival was a surprise to the Tates because he had not bothered to write and tell them he was coming. However, the Tates were very gracious and made room for Wilbur in their house.

It had taken Wilbur a week to journey from Dayton to Kitty Hawk. He stayed at the Tate’s house until Orville arrived two weeks later. Orville had an easier trip of four days. His only problem was his boat became becalmed on Albemarle Sound for a day because of no wind.

The people at Kitty Hawk thought they were eccentric as they dressed in suits as the middle class did in those days. The villagers also were not sure that God meant man to fly. But it turned out that it wasn’t long before the Wright were accepted.

Experiments Had Mixed Results

The results of their glider experiments were mixed. They used a spring scale to measure lift and measured the angle of attack and wind speed. Their biggest disappointment was that the glider did not produce as much lift as they had predicted. The unmanned glider would not fly in a wind of less than 22 mph. They thought it might be because they had had to substitute the two-foot shorter spars than called for in their design.

Their original design would have provided a wing area of 250 square feet. Because of the design change, the area was reduced to 165 square feet.

They also considered other causes of inadequate lift. The camber of the wing might be insufficient, the cloth used in the wings might not be sufficiently air tight, and the Lilienthal tables that they used in their lift calculations might be in error.

They mostly flew their glider as a kite, sometimes attached to a derrick. They even tried throwing it off the brow of a dune. Sometimes they placed chain on the craft to add weight. Young Tom Tate, Bill Tate’s eight-year-old nephew, rode the glider several times.

The first day they began glider experiments flying the glider as a kite. It didn’t take long before Wilbur wanted to try his hand at flying on the glider. Orville and Bill Tate each grabbed the wing tips on each side along with 15-20 feet of coiled line tied to each side. Wilbur took a position in the cutout on the middle of the lower wing. It was much like a beginner at hang gliding learns to fly today.

At Wilbur’s signal, all three ran with the glider into the wind. Wilbur jumped aboard and grabbed the elevator control while placing his feet on the T-bar at the rear.

Meanwhile Orville and Tate begin playing out the line slowly as the glider rose in the wind. At the height of 15-feet the glider began to pitch rapidly up and down. Wilbur yelled, “Let me down.”

Orville and Tate pulled on the ropes and gently the glider came down and landed without incident. Wilbur commented: “I promised Pop I would take care of myself.”

On September 23 Wilbur wrote to his father: “I do not intend to take dangerous chances, both because I have no wish to get hurt and because a fall would stop my  experimenting, which I would not like at all. The man who wishes to keep at the problem long enough to really learn anything positively must not take dangerous risks. Carelessness and over confidence are usually more dangerous than deliberately accepted risks.”

Wilbur decided that they would continue their testing with the glider unmanned. They erected a derrick from which a rope was attached to the glider. They would send the glider up to about 20 feet and control it by manipulation of strings attached to the elevator (they called it the rudder at that time). They had problems, however, because the glider wanted to keep climbing in the wind and when they pulled hard on the strings to bring it down, it would dart for the ground.

They decided that flying the kite from a tower wasn’t going to work. They then flew the glider from the ground but discovered that it was very difficult to manipulate the wing warping and rudder mechanism’s simultaneously. The problem seemed to be with the elevator.

The wing warping system for lateral control worked satisfactorily, but there were problems with the elevator used for pitch control (nose up and down). Orville wrote home to his sister, Katharine, “We tried it with tail (elevator) in front, behind, and every other way. When we got through, Will was so mixed up he couldn’t even theorize.”

They even tossed their unmanned glider off the brow of a dune to see what would happen. They learned that the glider would come down with little damage. That gave them confidence in the airworthiness of their design.

Their last day at Kitty Hawk, October 19, was perfect for gliding. Wilbur decided to get on and fly the glider again. The wing warping was tied off. Orville and Tate at the wingtips ran with the glider as long as possible to maintain lateral balance as it skimmed down the slope of the dune. By the end of the day Wilbur made a number of glides of 300-400 feet, lasting as long as 15 seconds, flying within 5-feet of the ground. This was as good as Octave Chanute and Lilienthal had been able to achieve. He was jubilant, sufficiently so to look forward to returning next year with an improved glider.

Before departure from Kitty Hawk, they gave the glider one last toss from the top of the dune. The Wrights told Mrs. Tate she could have the French sateen fabric covering the wings to make new dresses for her two daughters. One of her daughters, interviewed years later, still had her dress.

Although they were disappointed with the lift of their glider, they were pleased overall with their first attempt to fly. Wilbur wrote to Chanute, “The short time at our disposal for practice prevented as thorough tests of these features as we desired, but the results obtained were very favorable and experiments will be continued along the same line next year.”

They also had a good time on what they considered their vacation. They supplemented their food supply by hunting. “This is a great country for fishing and hunting,” Orville wrote to his sister. “The fish are so thick you see dozens of them whenever you look down into the water. The woods are filled with wild game, they say; even a few “b’ars” are prowling about the woods not far away.”

It was also significant that Orville became committed to the project and Wilbur for the first time began using “we” when describing their activities.

Roller Coaster Flight

by Dr. Richard Stimson

in The Kitty Hawk Years

When Wilbur made the first attempt to fly a powered machine on December 14, 1903, the Flyer rose in the air steeply to about fifteen feet, stalled and crashed into the sand. He blamed the crash on his unfamiliarity with the sensitive elevator control.

Forewarned, the four successful flights on December 17 were handled better but still resulted in roller coaster rides that could have flown farther if not for the sensitive elevator control.

This wasn’t the first time that they experienced problems using the elevator for pitch control. The elevator on their 1901 glider hardly worked at all. This was an unexpected result that they didn’t understand because they hadn’t experienced this problem with their previous year’s glider.

E. C. Huffaker and George Spratt, two of their visitors, suggested that the problem might be the reversal of the center-of-pressure on the wings. They had experienced similar problems in their own work.

The brothers didn’t think this was their problem because they were using a wing camber similar to what Otto Lilienthal had used successfully and they didn’t think he had run into this problem.

At this point in time the Wrights didn’t understand the true nature of the center-of- pressure on a curved wing and what was happening as the angle of attack changed.

Here is a brief explanation. When a flat surface is at right angles to a stream of air, the center of this pressure lies exactly at the center of the surface. As the angle of the surface is reduced (smaller angle of attack) the center-of-pressure moves forward toward the leading edge. It continues moving forward as the angle is reduced until the surface is parallel to the stream of air. The center-of-pressure is now directly against the leading edge.

The behavior of a curved surface operates differently. As the angle of attack decreases, the center-of-pressure moves towards the leading edge as before.

However, when the angle of attack nears zero, the center of pressure reverses and moves rearward on the surface. In the case of a cambered airplane wing, this movement of the center-of-pressure forces the rear of the wing upward and consequently the airplane into a sudden dive.

The Wrights decided to test the wing of their glider to determine what was happening. They removed the top wing of their glider and affixed two lines to the front edge. They flew the wing as a kite under a variety of wind conditions.

They observed that in light winds the wing pulled upward on the lines indicating that the center of pressure was in front of the center of gravity and the leading edge was forced upward.

In stronger winds the wings were forced down at a smaller angle of attack and pulled down on the lines. This demonstrated that the center of pressure had moved behind the center of gravity toward the trailing edge of the wing.

The brothers now knew that the control problem with the 1901 glider was caused by the sudden reversal of the center of pressure at low angles of attack. These sudden reversals required frequent movements of the forward elevator to maintain stability in pitch.

The back-and-forth center of pressure travel produces what is called a “pilot induced oscillation,” in which the pilot’s efforts to control pitch might actually make it worse.

Fortunately the Wrights had made the wings on the 1901 glider so that the camber could be easily adjusted. They reduced the camber from 1 in 12 to 1 in 19. The glider handled much better after the change.

The problem of pitch control returned in 1903. Part of the problem this time was that the elevator was hinged at its center. With this configuration, the airflow forced the elevator to sharply deflect on its own after only a small movement away from the neutral position. Once the oscillation started it was very difficult for the pilot to regain control of pitch, resulting in a roller coaster ride that ended with a premature crash into the sand.

The brothers had lengthened the lever that operated the elevator by four inches after Wilbur’s control problems on December 14th. It did provide 65% more leverage but it is doubtful that it did much good.

Despite their problems on December 17, 1903

The previous year at Kitty Hawk in 1900 the Wright Brothers found that the lift provided by the wings of their glider were less than predicted by published data developed by German aviation pioneer Otto Lilienthal in his “Aeronautical Annual.” They also had trouble when trying to make turns. The brothers returned in July 1901 with a redesigned glider that they hoped would solve the problems.

Their 1901 glider was a considerably larger version of the 1900 glider. They increased the camber (curvature) of the wings and lengthened the wingspan to 22 feet with a seven-foot chord (width). It weighed 98 pounds, nearly twice the weight of the previous year’s glider. The total area of the wing was 290 square feet, making this the largest glider that anyone had ever flown.

Also, the Wrights’ moved their camp from Kitty Hawk to Kill Devil Hills to take advantage of the large sand dunes there. Wilbur would start a flight by positioning himself in a horizontal position on the wing. When all was ready, the handlers would grasp the wing tips and run downhill as fast as they could into the wind.

Disappointing Results

Wilbur wrote to Katharine, his sister, “Our first experiments were rather disappointing. The machine refused to act like our machine last year and at times seemed to be entirely beyond control. On one occasion it began gliding off higher and higher until it finally came almost at a stop at a height variously estimated by Mr. Spratt and Huffaker (invited guests) at from 18 ft. to forty feet. This wound up in the most encouraging performance of the whole afternoon. This was the very fix Lilienthal had gotten into when he was killed. His machine dropped head first to the ground and his neck was broken. Our machine made a flat descent to the ground with no injury to either operator or machine.”

Fortunately serendipity was at work. Their unique design feature of a forward elevator had the effect of providing lift to bring the nose of the machine up whenever they encountered a stall. The glider would fall flat to the ground rather than in an uncontrollable dive. This was a great safety feature.

Modifications Help

In order to help determine why the glider wasn’t performing as expected they performed experiments flying the glider as a kite. As a result of their observations, they reduced the size of the elevator by almost half, hoping to improve the response to up and down commands. They reshaped the front spars to reduce drag and they flattened the camber of the wings from 1:12 to 1:19.

The modifications helped and Wilbur was able to achieve a long flight of 389 feet. The glider still didn’t achieve all their expectations. The lift was not much over 1/3 that should have been expected using the Lilienthal Lift Tables. They now suspected, but were not sure, that the Lilienthal data was in error.

Worse yet, they found another problem. Control of the glider was unpredictable when making a turn. When one wing was raised, the glider tended to slip to the opposite side of the turn.

They were now troubled. If proper lift could not be generated and if proper control could not be exercised, then controlled flight of a heavier than air machine was not possible.

Crash

Wilbur experienced these problems first hand when his glider crashed while trying to make a turn. The impact hurled Wilbur off the wing and into the front elevator, cutting his face, bruising his nose and blackening one eye.

Wilbur wrote about his concern to Octave Chanute: “The last week was without very great results though we proved that our machine does not turn (i.e. circle) toward the lowest wing under all circumstances, a very unlooked for result and one which completely upsets our theories as to the causes which produce the turning to right or left.”

Living Conditions

The weather and their living conditions did not help the Wrights’ state of mind. Their arrival at Kitty Hawk on July 10th was delayed by a violent storm with winds over 93 miles per hour. Orville wrote to Katharine that the “93-mile nor’easter demolished the only remaining piece of last year’s machine.”

The first night after arrival they stayed at Bill Tate’s house. (Tate was the one that had originally written to the Wrights’ about the advantages of doing their experiments at Kitty Hawk.)

Disturbed Sleep

The Tate’s had one hammock for the brothers to sleep in and it badly sagged in the middle. Orville wrote to his sister that when Wilbur slept in the bottom of the hammock, he (Orville) would have to hang on to the side of the hammock with both hands.

“When I played out and couldn’t stand it any longer, I rolled down into the bottom and made Will crawl up the side. The fellow in the bottom could get along pretty comfortably, for when he was attacked by any foe (which roams at large over most of the beds in these southern places) he had the opportunity of slapping back, but the poor fellow on the side was in a pretty fix, having both hands occupied, and had to endure the attacks the best he could.”

Mosquitoes Attack

After their arrival, it rained for a full week and that provided a perfect spawning ground for mosquitoes. According to Orville, “the mosquitoes arrived in a mighty cloud almost darkening the sun on July 18. “The sand and grass and trees and everything was fairly covered with them. They chewed us clear through our underwear and socks. Lumps began swelling up all over my body like hen’s eggs. We attempted to escape by going to bed, which we did at a little after five o’clock. We put our cots out under the awnings and wrapped up our blankets with only our noses protruding from the folds, thus exposing the least possible surface to attack.”

Water Shortage

The nearest water to their new camp at Kill Devil Hills was a mile away. They decided to install a Webbert pump but failed because they lost the point down in the sand. To get drinking water they placed a dishpan to collect rainwater running off the roof of the tent. The only problem was the water tasted like soap because they had previously rubbed soap on the canvas to keep it from mildewing.

Man Will Never Fly

Upon leaving Kitty Hawk, they stored the 1901 glider in their shed. The next year they used the uprights for their 1902 glider and destroyed what was left of the old glider.

Returning home to Dayton, they were dejected. Wilbur, not feeling well with a cold, declared, “Not within 50 years would man ever fly.”

Fortunately, his cold cured itself and the problem of wing lift and the control problem were solved during the next year. They were closing in fast on the first successful flight of their airplane in 1903.

George Spratt, a young physician from Coatesville, Pennsylvania, was a good friend of Wilbur and Orville Wright. He was interested in the possibility that man be able to fly from an early age and found a common field of interest with the Wrights. He was with the Wrights at Kitty Hawk during 1901, ’02 and ‘03.

They had a falling out in later years when Spratt claimed that the Wrights didn’t give him sufficient credit for technical suggestions he gave them. Twenty-one years after they met all communications ceased when Spratt, in a letter, called the Wrights “secretive, obstructive and lacking in vision and generosity.”

Spratt once wrote that he was fascinated by flying creatures since boyhood. “Flying has been the dream of my life. I never scared a bird up or saw a valley, but I longed to go with it and envied it.”

The Wrights found Spratt to be a kindred spirit that shared their interest in the study of aeronautics. He was congenial and liked to tell funny stories.

Unfortunately, Spratt had a tragic downside. He was prone to depression that seemed to grow worse with age. The Wrights called the affliction “the blues” and Wilbur on several occasions tried to pull him out of it.

Spratt had a scientific background, having graduated from medical school in 1894. Strangely, the 28-year-old soon after graduating gave up his medical practice, claiming it was too strenuous on his heart and took up farming, which would seem to be a more strenuous physical occupation.

Spratt began his involvement with the Wrights when, like Wilbur, Spratt wrote Octave Chanute seeking information on aeronautics and asked him for a critique on a paper he authored on the possibility of man-flight.

In his letter of 1898 to Chanute he said, “Being very much interested in flying machines and fully believing in their economical practicability, I have had my views on the subject type written and send you a copy. I wrote them down primarily that I might have clearer grounds for experimenting, but am getting discouraged accomplishing so little for various reasons, principally lack of sufficient funds. With the discouragement, boldness makes itself felt and I take this liberty of addressing you. The flying machine must come and it will soon come.

He continued, “Studying the subject principally from observation of birds, etc., in complete isolation from other interest, I am ignorant of the advance made. — Will you do me the favor of reading and criticizing the promises and conclusion? I will surely count it as a favor. Am I on the line of thought generally accepted as correct? How can I keep in touch with the advances made? I want to know more,  I want to do more.”

Spratt shared with Chanute that he was studying the movement of the center of pressure on a curved surface and had designed an apparatus for measuring the lift on airfoils.

Chanute was impressed with his interest and activity and encouraged Spratt to continue his study. He further suggested that Spratt devise methods of testing the lift and movement of the center of pressure on a cambered wing.

Chanute backed-up his encouragement with an offer to pay his expenses for his experiments, including the construction of a full-scale glider.

Even though Spratt had said that he had accomplished little because of insufficient funds, he refused the offer of money because he thought he would “bungle” the job. Apparently Spratt had little confidence in his own ability to actually construct something.

On June 26 and 27, 1901 Chanute visited the Wrights in Dayton where they had a good conversation on what the Wrights were doing and the state of aeronautics in general.

As a result of the visit, Chanute decided that he would provide as much support for the Wrights as he could.

Chanute believed that the complex problem of flight could best be solved through a team approach. Several days after their meeting in Dayton he wrote to the Wrights, offering to send two assistants at his expense to Kitty Hawk for their 1901 test flights. The Wrights didn’t want nor need any help, but didn’t wish to offend Chanute so they accepted his offer but not on the basis of the assistants working for them.

Edward Huffaker, who had worked for Samuel Langley and Spratt, were the two assistants.

The Wrights brought with them to Kitty Hawk the largest glider ever made. They hoped to have solved the previous year’s (1900) problem of inadequate lift. Spratt arrived for his first meeting with the Wrights on July 25, 1901.

While watching the Wrights assemble their glider, both Huffaker and Spratt warned the Wrights that they might encounter a pitching problem during flight because of a phenomenon wherein the center of pressure on a wing quickly reverses itself at low angles of attack. This could cause the pilot to lose control as the glider suddenly pitches downward. (Picture is of Spratt at Kitty Hawk)

The Wrights did experience problems with control and had to reduce the camber of the wings of their glider in order to minimize the phenomenon. The Wrights give credit to both men for pointing this problem out to them.

The Wrights returned home disappointed with their glider’s performance. They began to suspect that there were errors in the lift and drag data in the Lilienthal tables they were using to design their gliders. They decided to develop their own data.

During the lull in the activities at Kitty Hawk, Spratt shared with the Wrights some of his ideas about measuring lift and drift (drag is the modern term). Determining the value for drag was the most difficult to do. He suggested measuring drag as a ratio of “drift to lift” rather than trying to measure it directly.

Subsequently the Wrights designed two different clever mechanical balances for use in their wind tunnel they built. One balance was designed to measure lift and the other to measure drag. They were unlike anything that Spratt had suggested.

Calculation of Lift: Their lift balance measured the angle of deflection resulting from passing air over a sample airfoil and a reference flat surface. An indicator on the bottom of the device registered the angle of displacement in degrees caused by the amount of imbalance produced by the wind over the airfoil.

A mathematical calculation was made to find the value of a lift coefficient from the indicated angle (the sine of the indicated angle). Knowing the lift coefficient, the value of lift could be calculated from a lift equation.

Calculation of Drag: The Wrights built a second balance that directly measured the ratio of drag-to-lift as suggested by Spratt. Knowing the lift coefficient from the first balance and the drag-to-lift value from the second balance the coefficient of drag could be calculated.

The calculations were a time consuming job. Chanute spent some of his time helping them. The experiments consumed three weeks of effort. The development of the data was a remarkable achievement.

In 1902 Spratt again joined the Wrights at Kitty Hawk for glider trials. Wilbur told Spratt that the 1902 machine was “an immense improvement over last year’s machine.”

The Wrights continued to enjoy Spratt’s company and their debates on the finer points of aeronautical theory.

After Spratt returned home, he sent $10 to the Wrights to cover some of his expenses for his three-week stay in camp.

Wilbur wrote him back, “Moreover we feel that your help was worth more than your board, so you owe us nothing anyhow. — “We owe you, not you us.”

In truth Spratt had contributed little other than the pleasure of his company and the concept on which the drift balance had been based. The latter was the year before.

The Wrights continued their lively discussion through the mail.

Spratt was working on his own theories but he became discouraged as he viewed that his own progress was not proceeding as well as the Wrights. He also was having trouble coping with the rough and tumble of the Wrights debating style and the realization that he was losing most of the arguments.

Wilbur wrote, “I see that you are back at your old trick of giving up before you are half beaten in an argument.”

In another letter Wilbur chided him, “I felt pretty certain of my own ground but was anticipating the pleasure of a good scrap before the matter was settled. Discussion brings out new ways of looking at things and helps round off the corners.”

Spratt in turn complained that their method of rounding off the corners by switching sides in the middle of an argument struck him as dishonest.

Spratt was invited back again to Kitty Hawk in 1903 to witness the attempt for the first manned-flight of the Flyer. Spratt, a good worker, helped construct the sixty-foot monorail to be used for launching the Flyer.

On November 5, the Wrights started the engine on the Flyer for the first time. The engine ran, but the vibration from several missed explosions caused one of the propeller shafts to twist. The shaft would need repair and both of the shafts strengthened. That would require sending them back to Dayton for repair as soon as possible.

Spratt decided to leave camp for home. He was upset and convinced that the Wrights were heading for disaster. He volunteered to take the shafts with him and arrange to have them shipped back to Dayton from the mainland.

The Wrights didn’t see Spratt again until 1906 although they kept up their correspondence during the interval. In one letter Orville described his joy at their accomplishments by writing, “Isn’t it astonishing that all of these secrets have been preserved for so many years so that we could discover them!”

In another letter Wilbur tried to get Spratt out of one of his periodic bouts of the blues: “I am sorry to find you back at your old habit of introspection, leading to a fit of the blues. Quit it! It does you no good and it does do harm.”

The Wrights were on a business trip in 1906 and stopped by Spratt’s farm in Coatesville for a side visit on their way from New York to Philadelphia. Spratt spoke of an airplane he was designing that didn’t need warping of wings, use of ailerons or a moveable tail to exercise control. He called it the “Equilibrium Machine.”

Spratt believed that the design of the Wrights’ system of control was unsafe. He believed that a way should be found to design a machine that was automatically stable. Spratt later complained that Orville and Wilbur didn’t show any interest in his idea.

By now Spratt was increasingly obsessed with the idea that he hadn’t received credit for being the one that told the Wrights about the measurement of the lift/drag ratio.

In 1908 he sent a harsh letter to the Wrights accusing them of depriving him of the credit for the design of the lift balance used in their wind tunnel experiments in 1901.

Wilbur answered, “We have not wished to deprive you of the credit for the idea, and when we give the world that part of our work, we shall certainly give you further credit.” “— But while we considered the idea good, I must confess that I am surprised and a trifle hurt when you say that the advice and suggestions we gave you in return cannot be considered in any degree a fair compensation.” “— But aside from the ideas and suggestions you received from us, we also furnished you copies of our tables, not only those made on the machine ( drag balance) of which your idea formed a part, but also on the pressure testing machine (lift balance).” — “I can cannot help feel that in so doing we returned the loan with interest, and that the interest many times outweighed in value the loan itself.”

In 1922, Orville was compiling a history of the development of the first airplane and wrote Spratt asking for copies of letters that Wilbur and he had written to him about their wind tunnel and propeller experiments.

Spratt responded by repeating his grievance and refused to send the documents. The friendship soured. Orville never wrote to him again.

One month before Spratt died in November 1934, he flew an airplane that he built. Spratt claimed that the machine incorporated all of his theories about airplane stability that he had devoted most of his life discovering.

It was a bizarre airplane. In an old film clip, Spratt is shown suspended like the weight on a pendulum several feet below the wings of the frail biplane.

Sprat claimed that the machine incorporated all of his theories about airplane stability that he had devoted most of his life discovering.

It is a sad commentary on Spratt’s life that a man who had been a confident of the Wrights and an eye witness to the events at Kitty Hawk, was featured with his airplane in a humorous newsreel clip called Aeronautical Oddities.

References: The Bishops Boys by Tom Crouch; Wilbur and Orville by Fred Howard; “The Forgotten Third Wright Brother” by Joe D’Angelo, Coatesville Ledger.

Returning to Dayton after their 1901 glider experiments at Kitty Hawk, Orville and particularly Wilbur were dejected. The glider did glide but the lift generated by their glider was much less than they had expected and they experienced control problems as well. Wilbur was so puzzled that he declared, “Not within a thousand years would man ever fly.”

The Speech

Shortly after returning home, an unexpected event shook Wilbur out of his funk. He received a letter from his friend, Octave Chanute inviting him to be the featured speaker at the upcoming meeting of the Western Society of Engineers in Chicago.

His immediate reaction was to refuse the invitation. Katharine, however, thought it would be a wonderful occasion to introduce her brother to influential people. She prevailed upon him to accept.

In a letter to their father Milton, she admitted, “Will was about to refuse but I nagged him into going.”

There was one other problem. Wilbur didn’t have any suitable clothes to wear for such an occasion. Orville, who always dressed well, offered his.

“We had a picnic getting Will off to Chicago,” Katharine wrote to her father. “Orville offered all his clothes so off went Ullam (Wilbur), arrayed in Orv’s shirt, collars, cuffs, cuff-links and overcoat. We discovered that to some extent clothes do make the man for you never saw Will look so swell.”

“We asked him (Wilbur) whether it (the speech) was to be witty or scientific,” wrote Katharine, “and he said it would be pathetic before he got through with it.”

Wilbur titled his speech, “Late Gliding Experiments.” Thinking about what he was going to say forced him to think seriously about what caused the lift problem. He decided that the trouble was with the Lilienthal data for curved airfoils that they had used to calculate wing size and shape.

In his Chicago speech, Wilbur boldly declared that the data in the Lilienthal tables contained serious errors. “The lifting capacity seemed scarcely 1/3 of the calculated amount.”

The speech was printed in the December, 1901 issue of the Journal of the Western Society of Engineers. The written version, however, was toned down somewhat. At this point Wilbur had no proof of his claim.

Wilbur also told his audience that “… if you are looking for perfect safety, you will do well to sit on a fence and watch the birds; but if you really wish to learn you must mount a machine and become acquainted with its tricks by actual trial.”

The speech was important because it gave Wilbur a new boost in confidence. These were people of high position. Their acceptance of what he said was a big moment for him.

The Wind Tunnel Experiments

The Wrights decided they needed to generate their own data to support their assertion that there was something wrong with the historical data they were using in their calculations. These test reveal the true genius of the Wrights.

Orville designed and their employee Charlie Taylor built a wind tunnel.

It consisted of a wooden box, six feet long, sixteen inches on a side, with a window on top that allowed the interior to be viewed. A fan mounted at one end was capable of producing 25 to 35 mph winds. They also created the instrumentation necessary to measure lift and drag forces at various angles and the effect of lift on varying wing curvatures as well as leading and trailing edge thickness. This was the first use of a wind tunnel to conduct aeronautical research.

Initially, they had mounted a bicycle wheel rim free to spin horizontally on a bike to test the wing shapes. The results showed they were on the right track, but the apparatus didn’t work very well.

Orville followed that up by building a small wind tunnel out of a starch box while Wilbur was in Chicago.

Their final wind tunnel was one of just ten existing in the world and the third in the U.S. The other wind tunnels were in academic environments and were used for specific airflow studies. The Wrights were interested in designing a wing, not theoretical studies.

The one trouble they had with the wind tunnel was that it produced too much turbulence. To correct the problem, they built a baffle in front of the fan. Modern wind tunnels place the fan at the other end so as to pull the air through the tunnel.

They conducted parametric studies (e.g. compare long, narrow wings with short, narrow ones) with nearly 200 different miniature metal wing foils in their wind tunnel, including stacked wings. Based on this data they determined the most efficient shape or configuration to create the most lift with the least drag. In the course of their tests over a period of only two months they redefined aeronautics for the next century.

Among other things, they proved the fallacy of sharp edges at the front of wings, the inefficiency of deeply cambered wings and the inefficiency of wings with low aspect ratio (short length, narrow wings). These were design features thought important by others.

They found that the Lilienthal data was valid only for the specific shape of the wing used by him. That and another factor they discovered was in error, known as the Smeaton coefficient, caused them to overestimate the lift of their gliders by 40%.

Wilbur wrote to Chanute: “I am absolutely certain that Lilienthal’s table is very seriously in error. But that the error is not so great as I had previously estimated.” (Wilbur found that the Lilienthal data wasn’t that much in error, the major error was in the value of the Smeaton coefficient.) Chanute, had trouble grasping their ideas.

Now, for the first time, wings could be designed efficient enough to support the flight of a machine. This was an important breakthrough because the Wrights established an important concept ignored by others. It is the wings, not the engine, which lifts an airplane into the air.

Their wind tunnel results permitted them to rapidly close in on being able to fly. Everybody else was designing “full scale.” Build a full-scale glider, see the results; then go back and build another one. This was a wasteful trial-and-error approach that cost money and time.

In contrast the Wrights completed all of their work in six weeks by working fourteen hours a day and finished in time to enjoy Christmas with their family.

The glider experiments at Kill Devil Hills in 1902 were to put to the test all the Wright Brothers research on flight. They knew they were closing in on the secret of flight.

Their data exceeded anything that was to be available for the next decade. They used their new data to build a larger glider that for the first time added a twin tail. Also, they changed the manipulation of the wing warping from foot control to the movement of the hips in a cradle on the lower wing.

Both the wing warping and the elevator controls were made more instinctive for the pilot. For example, the pilot would shift his weight to the high wing when the glider tipped.

Back in 1899 the brothers thought they might make some contribution to man’s effort to fly. Now they were confident that they could solve the problem of flight by themselves.

Orville later wrote, “When we were carrying on our wind-tunnel work we had no thought of ever trying to build a powered plane. We did the work just for the fun we got out of learning new truths.” After the plane’s performance affirmed the accuracy of their tables, Orville said, “we saw it would not be hard to design a man-carrying power aeroplane.”

The Third Trip to Kitty Hawk

The prior trips to Kitty Hawk were difficult and living was basic outdoor camping. This trip they were determined to camp in comfort.

The trip to Kitty Hawk, unlike the first two, was problem free. Upon arrival on August 28th they set about expanding and improving the crude building they had built the year before that was badly in need of repair. They now had a combination kitchen, dining room and bedroom. Their dining table consisted of oilcloth over two thicknesses of burlap. Their beds were reached by a ladder and consisted of two thicknesses of heavy burlap stretched between wooden frames up among the rafters. It was rustic, but a vast improvement from tent living.

“Will is thin and so is Orv,” Katharine wrote to their father. “They will be all right when they get down in the sand where salt breezes blow, etc. They think that life at Kitty Hawk cures all ills you know.”

The Mouse

Soon after arrival, they had an uninvited guest, a mouse, whose noises while searching for food kept them awake at night. Orville built a mousetrap to get the mouse. He confidently called it the death trap.

That night Orville was awakened with the mouse crawling over his face. Orville, with his dry humor, commented that the mouse was waking him up to put more corn bread in the trap.

He never did catch the smart little mouse. It was found dead ten days later under a trunk.

Gliding Experiments

It took three weeks to assemble their glider.

During the day, the Wrights’ concentrated on flying. Wilbur in his Chicago speech said that the key to the secret of flying is practice. It was like learning to ride a horse.

One of their critical concerns was whether the wings they had designed using the data from their wind tunnel tests would generate sufficient lift. They based the design of the glider’s wings on airfoil number 12.

Their test data predicted a long, narrow wing is more efficient than a shorter one with the same area. The 1902 glider’s wing span was ten feet longer than the previous year’s glider and the cord was two feet shorter. As expected, they found the 32-foot wings with a 5-foot cord and chamber of close to 1:30 provided excellent lift.

Another feature of their new glider was that the wings were set in a negative dihedral. In other words they drooped. This feature provided greater stability and pilot control.

Perfecting the Turn

They had another concern. This one was with the wing warping mechanism that they used to control roll from side-to-side.

The design provided for the wings to be warped by the sideways movements of the pilot’s hips. The pilot was prone in a cradle (used for the first time) attached to warping wires that in turn were attached to the wings. In such a fashion the pilot could control the lateral direction of the glider.

They had added a fixed vertical double tail to their new glider to improve control while making a turn. They found that control was improved but not perfect.

Performance exceeded expectations except under some mystifying conditions, instead of the glider righting itself when the wing warping was applied, the craft would go into a tailspin. The Wrights called the phenomenon “well-digging,” because one wing tip would be forced into the ground with a screwing action.

This was a serious problem because most flying accidents are caused by a stall-spin sequence.

Orville solved the problem. One night he had trouble sleeping because he drank too much coffee. Not one to waste time, he thought about the problem. His solution was to change the double tail to a single tail and make the tail movable like a ship’s rudder.

As was typical, when one Wright brother had an idea, the other would improve on it. Part of their success in solving problems was derived from the fact that they were a great team.

Wilbur suggested that the wires used for wing warping should also be interconnected with the rudder control wires. In that way the two could be synchronized.

The glider could now be rolled left or right while still maintaining stability and control in flight. Also, the pilot could control two things at once, instead of three.

The wing warping cradle mechanism simultaneously controlled the wings and the tail, and a vertical lever operated by hand was used to control the elevator. In this way they could perform the basic aerial maneuvers necessary for controlled flight about three axes.

Success

Some 1,000 glides, the longest being 622.5 feet in 26 seconds, demonstrated that they had solved most of the problems of stability and control and had the first workable airplane. They demonstrated that control and stability were related and that an airplane turned by rolling. The glider could hover like a bird, and turn and fly at right angles to the wind. Orville longest flight was 615.5 feet.

Their basic patent issued in 1906 was based on their concept of flight control used on this glider. The Wrights were forced to defend their patent many times, but never lost a court fight. It has withstood the test of time and still defines the basis for flight of all machines that fly, including the space shuttle.

Visitors in Camp

Octave Chanute asked the Wrights if he could bring two gliders of different designs to their camp for testing. Chanute wanted them to observe these designs with the hope that the gliders would attain automatic stability in flight. The Wrights humored Chanute, believing a better approach was to use human control as they were doing.

Chanute brought with him Augustus Herring to assemble and fly the gliders. One glider was a multi-wing machine that Chanute had designed, and the other was an oscillating-wing machine that a C. H. Lamson, of kite fame had designed. Neither flew successfully.

Herring turned out to be a scoundrel who would cause the Wrights trouble in the future. For example, after the Wrights filed for their patent in 1903, Herring wrote them and falsely claimed he held a prior patent on a machine similar to theirs and wanted a 1/3 interest in their machine.

Also in camp were George Spratt, a flying enthusiast and friend whom the Wrights invited, and a surprise visitor, their older brother Lorin.

Gliding with Ease

Orville and Wilbur made up for lost time after the “crowd” left.

“The past five days have been the most satisfactory for gliding that we have had,” Orville wrote Katharine. “In two days we made 250 glides, or more than we had made all together up to the time Lorin left. We have gained considerable proficiency in the handling of the machine now, so that we are able to take it out in any kind of weather. Day before yesterday we had a wind of 16 meters per second or about 30 mile per hour, and glided in it without any trouble. That was the highest wind a gliding machine was ever in, so that we now hold all the records! The largest machine we handled in any kind of weather, made the longest distance glide (American), the longest time in the air, the smallest angle of descent, and the highest wind!!! Well, I’ll leave the rest of the “blow” till we get home.”

Orville and Wilbur were having fun flying.

After five weeks of testing, they broke camp October 28th to return to Dayton.

They were ready to work on the design of a new machine that they proposed to propel through the air with propellers driven with a gas engine.

Note: A reproduction of the 1902 glider that was built under Orville Wright’s guidance is on display at the Wright Brothers National Memorial, Kitty Hawk, N.C.