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The Discoverers of Modern Aerodynamics

by Ryan Clarke

After centuries of demoralizing carnage as men tried to gain the air by jumping off high towers with only homemade ‘wings’ strapped to their arms, the only thing left of man’s dream to fly was the dream. Finally, as the world entered the modern scientific era, scientists saw the futility of imitating the birds. These men realized that solving the problem of human flight was more than a simple ‘flap and go,’ scientific laws governed the air. Yet even this new knowledge failed to create a plane that flew because this knowledge was still incomplete. Just when it looked like soaring was impossible for a person, the door of the air age was thrust open. Though many other men had tried before to conquer heavier-than-air flight, Wilbur and Orville Wright were the first men in history to understand all the principles and design all the major elements necessary to build the world’s first successful airplane.

Even before the Wright’s historic flight a number of machines had flown . However, none of these can be considered a “successful airplane” because they did not meet five essential qualifications. The most basic criterion was the need for the plane to carry a person. The plane must also be able to take off from level ground under its own power and fly forward under that power without slowing until it lands at a spot level with or higher than the point at which it took off. Orville Wright described these requirements as portrayed in his first 1903 flight this way: “. . . a machine carrying a man had raised itself by its own power into the air in full fight, had sailed forward without reduction of speed, and had finally landed at a point as high as that from which it started.” (Wright, “Made” 13) Here, Orville does not mention the most important requirement, that it must be controllable in the air, because he rightly believed that any flight would be impossible without human command over the airplane. (Howard, Wilbur 32)

To fulfil these five requirements and thus make a successful airplane, successful meaning that it works well and actually flies, a designer must include all the major and necessary components of an airplane. The most obvious one is lift that comes from the wings. The plane must also have stability and control, and to get the machine off the ground: power creating thrust. (Boyne, “Century” 68) The Wright brothers were the first to combine all these principles into a single machine, and so were the first to fly.

The Wright brothers assumed that lift was obviously not going to be a problem since other men had “flown,” so they tackled the problem of stability and control first. Stability is state of being stable in which the airplane will continue to head in the original direction at an even keel without turning on any axis. Certain arrangements of the wings and tail create this equilibrium. However, in an imperfect environment, such as the air outdoors, a sudden gust of wind can easily overturn this stability. Control is the ability of a person to influence the attitude of the plane. This is necessary for regaining equilibrium after that gust of wind or for upsetting equilibrium to turn, rise or descend. (Becker, Dreams 149)

In the reading they did on other pioneers in flight, the Wright brothers were shocked to find how little attention these men had paid to the problem of control. (Howard, Wilbur 32) The most respected and experienced flier at the time was Otto Lilienthal. He designed his gliders to be inherently stable and he righted any gust action by hanging from his armpits and swinging his body and legs. (Harris, First 23) Thus, he could swing his body any way he needed to bring the higher wing down. Octave Chanute followed Lilienthal’s example and controlled his gliders the same way. Neither man was extremely successful and Lilienthal died when his glider overturned in spite of his swinging due to a particularly large gust. (Harris, First 24) Samuel Langley in his “aerodromes,” as he called his steam-powered planes, discarded then idea of controllability completely. Instead he relied on stability alone, making his aerodromes unsuitable for any weather except a dead calm. (Becker, Dreams 136)

As the Wright brothers read the accounts of these men who had gone before, they were impressed with the idea that perhaps they could succeed if they could find a workable system of control. The Wrights realized that the problem was not to get stability, but to get control over the aircraft. (Harris, First 26) Because of this, they developed a control system for all three axises. The first part was obvious: a small flat wing in front of the plane to regulate the airplane’s pitch fore and aft. It turned out that theirs was the most effective elevator yet designed. They also put it in front, instead of behind like many others, to increase control. They next conquered lateral (wingtip to wingtip) stability by wing warping. No one who had proceeded them had ever thought about lateral control, but this was the major problem inherent in aircraft of that day. With wing warping, one wind twists to point upward creating more lift while the other wing twists down. (Becker, Dreams 149) This makes the airplane rotate along its length. Wing warping enabled them to build larger machines that their contemporaries because the amount of wing area they could ‘balance’ was not dependant on their weight, but on how much warping the pilot applies. (Kelly, Wright 67) The Wrights then completed their control system by adding a rudder. Everyone before them used the rudder, like a rudder on a ship, to turn to the plane. The Wrights understood that the rudder’s true purpose is to balance the warping action by putting the air pressure on the side opposite of the direction of the turn, which is reverse of the principles on a ship. (Kelly, Wright 297) Since a stable plane would want to go ahead continuously, the Wrights made their plane unstable on purpose to allow the control system to be more effective. In all, the Wright brothers fathered the modern control theory and design of all future airplanes in every aspect.

Lift is arguably the most important force necessary to fly. A modern efficient wing, such as is used on most planes, is curved to be convex upward. As wind passes over this curved surface, the air moving over the rounded upper side speeds up. This faster moving air has a lower pressure than the air under the wing and this is how the air sucks the wing up. This force is essential to overcome the gravity holding the craft on the ground. However, there is another facet to the problem of gaining enough lift. The amount of curve in the wing, called camber, changes the amount of lift the wing produces. (Harris, First 41-43) If the camber is not of an efficient enough shape, the lift probably will not raise the plane’s weight. Fortunately, Otto Lilienthal calculated out some tables the told airplane designers exactly how much camber to use to get the needed amount of lift.

As basic as the need for lift is, many early experimenters failed greatly because they did not understand the principles that govern flying wings. Clement Ader supposedly got his Eole to struggle of the ground for a short hop while tethered to a pole on a circular track in 1890. (Becker, Dreams 122) He used flexible wings with a curious adjustable camber system, a contraption which was not at all good for creating lift. Encouraged by what he thought was success, Ader built two more planes, but neither even came close to flying. Lilienthal went about solving lift more scientifically, but even his gliders did not always perform well. Chanute, who used Lilienthal’s lift tables, never seemed to be happy with the lift he got from his 1896-97 glider which was his most successful, since he spent the rest of his life looking for new wing constructions, patterns and arrangements. Even during the years following the Wrights success, the Europeans were just barely struggling off the ground and this only because their engines were powerful enough to pull the inefficient wings. (Harris, First 101) The lift generated by a wing, though basic to flight, was not fully understood before or for many years after the Wright brother’s successful flights.

Since Lilienthal had already formulated the lift tables they needed, Wilbur and Orville decided to use them to build their planes. They were very pleased with their 1900 and 1901 gliders since the revolutionary control system worked so successfully. However, the lift that the wings generated was not even close to the amount they had calculated and depended on. (Howard, Wilbur 63) Since both gliders’ performance pointed to this inaccurate lifting power, the Wrights decided to reevaluate Lilienthal’s calculations. A few crude tests that Orville made proved that Lilienthal’s numbers were wrong. (Kelly, Wright 74) The brothers then began the long task of testing numerous surfaces of numerous curves at numerous angles and numerous speeds in a little wind tunnel they designed with a balancing mechanism they invented. Through all this tedious work they created the first accurate lift tables ever made. (Harris, First 44-46) In fact, even years later with highly sensitive instruments scientists have been unable to get much more accurate figures than the Wright’s got in their homemade tunnel. This new knowledge of lift that the brothers found not only enabled them to get more weight off the ground with less wing area, but also gave them a firm understanding of their control surfaces and laid the groundwork for their experiments in propellor thrust production. (Becker, Dreams 153)

The key ingredient in powering a plane is thrust. In the early experiments to develop powered flight, the main obstacle that seemed to be blocking the way was a strong enough engine that was not too heavy. However, the real need was not a good power to weight ratio but an efficient propeller to turn the available power into forward energy. Designing propellers was very much a matter of guesswork and knack. (Boyne, “Century” 78) Thus, even after some new light and powerful motors became available, the airplane experimenters were still not able to get off the ground. In whatever way some of these pioneers rose into the air, it was because they had what is needed to push any airplane forward: sufficient thrust.

Many of the most promising attempts at powered flight failed because of a lack of thrust. In 1866 John Stringfellow built a model triplane which he flew in the Crystal Palace in London. After lifting off the wire it hung from, it was unable to maintain its forward momentum in spite of having the best steam engine made up to that time. (Becker, Dreams 106) Clement Ader’s Eole, though it is said to have flown, only managed a short hop because its thrust was also insufficient. However, not all experimenters had a problem with thrust. Sir Hiram Maxim built a three and a half ton goliath powered by two steam powerhouses producing 360 horsepower. These turned two propellers more than seventeen feet long. (Becker, Dreams 124) In his only flight attempt, Maxim’s plane lifted forcefully off the rails it ran on and crushed through the stop pads at the end of the track. Maxim did not have efficient wings or decent propellers or any control or stability. All he proved was that a huge mass of sheer force could claw its way into the air. Samuel Langley did not get so power hungry in his aerodromes. However, though his 1896 models flew well, the 1903 man-carrying craft was unable to withstand the shocks of the power his steam engine produced. (Howard, Wilbur 131) Even if Langley had built his 1903 aerodrome stronger, it still would not have flown since the extra weight would have cancelled out the extra thrust he had. What man needed to fly was not more power, but more thrust, and that comes from more efficient propellers.

Wilbur and Orville were finally ready by 1903 to begin the process of adding power to their successful glider designs, and their solution solved the problem of flight. After shopping around, the Wrights were unable to find a light enough engine in America so they decided to build their own. (Becker, Dreams 156-157) They needed the motor to be less than 180 pounds and generate 8 horsepower. They got 12 horsepower with only 150 pounds. Then they calculated that they needed 66 percent propeller efficiency to generate enough lift. (Howard, Wilbur 107) This is when they discovered that propeller theory was not even theory: it was all guesswork. So, armed with the knowledge of their wing lift tables, the Wright brothers set about and thought up the theory of propeller motion, principles which are still used today. Using this data, the brothers designed a propeller that generated the needed 66 percent efficiency, which is one third more than either Maxim or Langley’s propellers. Though the Wright’s will not be remembered for their engine, their propellers led the way into modern thrust production and enabled the first sustained flights. (Boyne, “Century” 78)

Why did scores of men, many of them very smart, fail to conquer the air or even produce correct information? One reason was they did not bother to research and understand what was known about the air. They also did not make sure they only worked with correct information. Many were also too sure that they had the one magic ingredient that would make the plane fly. However, the main reason was that they did not systematically discover and solve every element and principle necessary to make an airplane. (Harris, First 22)

Why did two young Wright brothers, neither with even a high-school diploma, (Kelly, Wright 23-24) solve the imposing problem of flight almost by themselves? Because they carefully learned what was known then. Then they diligently sorted out the error and analyzed other’s mistakes to learn from them. They also evaluated their own results whether successful or not. Most of all, they developed and understood every key ingredient of the airplane and every major law flight. (Harris, First 22)

Looking at the Wright 1903 Flyer hanging in the Smithsonian Air and Space Museum, people wonder how that primitive looking contraption actually got off the ground, let alone changed history. They do not realize how scientific the Flyer is. Every school child knows that the Wright brothers flew the first airplane. However, people desperately need to tell the story of two American boys who had the ingenuity and diligence to think of and build everything necessary to make flight a reality when everyone else had failed and lost all hope.

WORKS CITED

Becker, Beril. Dreams and Realities of the Conquest of the Skies. New York: Atheneum, 1967

Boyne, Walter J. “A Century of Flight.” Popular Mechanics, Dec. 2003, 68-81

Harris, Sherwood. The First to Fly: Aviation’s Pioneer Days. New York: Simon and Schuster, 1970

Howard, Fred. Wilbur and Orville: A Biography of the Wright Brothers. New York: Alfred A. Knoff, 1987

Kelly, Fred C. The Wright Brothers: A Biography Authorized by Orville Wright. New York: Harcourt, Brace and Company, Inc., 1943

Wright, Orville. “How We Made the First Flight.” Flying, Dec. 1913, 10-12, 35, 36