This article discusses work of engineers apart from Wright Brothers in the field of aviation. Octave Chanute, an American who made his fortune as a railroad and bridge engineer, began to try his hand at flight in 1875. A German engineer, Otto Lilienthal, who was achieving international fame with spectacular flights in hang gliders of his own design, inspired William Randolph Hearst. Lilienthal made steady progress until 1896, when his glider stalled, and he fell to the ground and died from internal injuries. Samuel Pierpont Langley, a professor of physics, after securing research funds, began to measure how much power was required to lift a weight with a wing moving through the air. He used a technique for testing air foils that had been described 50 years earlier by Sir George Cayley. Langley estimated that human flight would require an engine of at least 12 hp. In 1899, his friend Robert Thurston, a Cornell engineering professor, introduced him to Charles Manly, who had graduated from Cornell as a mechanical engineer.
When we look back at the Wright Brothers’ 1903 first flight, from our perspective it is a milestone in human history.
The Wright Brothers were not the first aeronautical engineers in the United States. Technically, they weren’t engineers at all by training or according to conventional credentials. But they did what many pundits of their time declared impossible: get a man aloft in a heavier-than-air machine under its own power.
For largely commercial reasons, though, decades passed before everyone agreed that they were, in fact, the first to launch a practical airplane. The Wright Flyer wasn’t enshrined in an American museum until 1948.
Octave Chanute, an American who made his fortune as a railroad and bridge engineer, began to try his hand at flight in 1875. He summarized contemporary knowledge in his 1894 book, Progress in Flying Machines, and designed a biplane hang glider using structural techniques similar to his bridge trusses.
Meanwhile, a German engineer, Otto Lilienthal, who was achieving international fame with spectacular flights in hang gliders of his own design, inspired William Randolph Hearst. Hearst bought a Lilienthal glider and paid daredevils to fly over the beaches of New Jersey and Staten Island. Reports of the flights boosted circulation of Hearst newspapers. Lilienthal made steady progress until 1896, when his glider stalled, and he fell to the ground and died from internal injuries.
Frank Wicks is a professor of mechanical engineering at Union College in Schenectady, N.Y., and is a pilot of gliders and powered aircraft.
Samuel Pierpont Langley was professor of physics and astronomy at the University of Pittsburgh’s Allegheny Observatory, where he had invented instruments for measuring solar radiation. In 1886, the year before he was named secretary of the Smithsonian Institution in Washington, Langley traveled to Buffalo, N.Y., for a meeting of the American Association for the Advancement of Science. He attended lectures on flight and would devote much of his remaining years to the challenge.
When he secured research funds, Langley began to measure how much power was required to lift a weight with a wing moving through the air. He used a technique for testing air foils that had been described 50 years earlier by Sir George Cayley. A wing could be attached to a 30-foot-long arm rotating at up to 70 miles per hour on a horizontal plane.
The lift and drag forces were difficult to measure. In an 1891 paper, “Experiments in Aerodynamics,” Langley concluded the higher the speed, the lower the drag. This incorrect conclusion was accepted at the time and named Langley’s Law. He experimented with models that used two wings in tandem with a propeller powered by a small steam engine.
Langley was joined by Alexander Graham Bell who, 20 years after he invented the telephone, said he was more interested in flight. Langley achieved a remarkably successful flight on May 16, 1896, when his fifth model traveled 3,300 feet in a circular path at a speed of about 25 mph before running out of fuel.
Langley and Bell were elated. The aircraft weighed 30 pounds and had a 7-foot wing span. It was powered by a 1-hp steam engine with a boiler pressure of 90 psi driving the propeller at 700 rpm. For the first time, a large model with a self-contained power plant had demonstrated heavier-than-air flight.
That was the year in which William McKinley was elected president, and he appointed the young Theodore Roosevelt assistant secretary of the Navy. When the war against Spain materialized after the sinking of the battleship Maine in Havana Harbor, the United States suddenly became a world power.
Langley solicited McKinley and Roosevelt for funds to construct a man-carrying flying machine for future military missions. In 1898, Congress authorized $50,000 for the project.
Langley understood a practical machine that could carry a human over a significant distance could not be powered by steam engines.
It was still eight years before Henry Ford would introduce the Model T as the first mass-produced automobile, but gasoline engines were beginning to compete with steam and electric for the few customized cars that existed. Langley estimated that human flight would require an engine of at least 12 hp.
In 1899, his friend Robert Thurston, a Cornell engineering professor, introduced him to Charles Manly, who had graduated from Cornell as a mechanical engineer.
Manly went to work for Langley. He modified a 6-hp engine that had five rotating air-cooled cylinders and a fixed crankshaft to a radial engine with fixed cylinders and a rotating crankshaft. Next, he converted from air to water cooling by adding jackets to the cylinders. By June 1901, he had nearly quadrupled the output to 22 hp.
Manly increased displacement from 380 to 540 cubic inches, which required casting new cylinders and cooling jackets. He improved the ignition and carburetor. By March 1903, in static tests the 130-lb. engine produced 52 hp as it turned twin propellers at 575 rpm.
After 17 years, Langley’s dream of powered human flight finally seemed attainable. The first manned flight, on Oct. 7, 1903, would be launched by a 60-foot catapult from the roof of a houseboat that also served as a machine shop anchored on the Potomac River. Reporters, photographers, and sightseers turned out in hopes of witnessing history. Manly, the pilot, had strapped a compass to his leg to aid in navigating a long flight.
Manly took his place at the controls. The unmuffled engine was running smoothly. The launch signal was the firing of two rockets followed by two toots from a tugboat. A mechanic cut the holding cable. The catapult moved the plane forward. There was a roaring and grinding noise as the airship tumbled 16 feet into water.
Manly was unhurt. Langley blamed a fouled launching mechanism. They tried and failed again on December 8. On this launch, the nose angled up before the splashdown. This time, Manly barely survived and the aircraft was badly damaged. It is improbable that the necessary flying speed was achieved.
Members of Congress and the press began to call it Langley’s Folly. The government withdrew support. Langley had to abandon his dream and died in 1906.
Many experts were skeptical that flight was even possible. Admiral George Melville, the Navy’s chief engineer and a president of ASME, received acclaim for his vision of converting ship propulsion from reciprocating steam engines to the newly developed turbines. When it came to the possibilities of human flight, the admiral was a skeptic who wrote with authority. He had written about flight in the December 1901 issue of North American Review that “a calm survey of natural phenomena leads the engineer to pronounce all confident prophecies for future success as wholly unwarranted, if not absurd.”
An editorial in The New York Times said Langley’s fiasco was not unexpected by experts because of the existing relationship between the weight and strength of materials. The editorial predicted that a flying machine might take a million years of efforts by mathematicians and mechanicians.
It actually took nine days after Langley’s final failure. The flying machine that Wilbur and Orville Wright had developed with their own funds performed the epic feat on Dec. 17, 1903. Attention was minimal. It was not reported by The New York Times. There were only five witnesses and a camera.
The brothers’ success immediately after Langley’s well-funded failure was astonishing. Neither brother was a high school graduate. It was suggested that they stumbled into the sky almost by accident.
However, the revised view of present-day historians of science and technology is that Wilbur and Orville Wright were possibly the most remarkable scientific and engineering team in history. Their work has become a favored topic for engineering case studies.
Their mother, Susan, was recognized as an inventive woman skilled in handicrafts. Their father, Milton, was a prominent, sometimes outspoken, much-traveled bishop with the Church of the United Brethren of Christ. He sometimes suggested that his sons take time off trom school to pursue their own intellectual interests.
The bishop was also a firm believer in the value of educational toys. In 1871, Alphonse Penauld had developed rubber band-powered monoplanes and helicopters. When Wilbur was 11 and Orville 7, they received one of these toys, which they shared, like all of their future endeavors.
Their serious effort started in May 1900 with a letter from Wilbur to the 68-year-old Octave Chanute. Wilbur said he had become inflicted with the disease that caused him to believe that flight was possible, and feared it would soon cost him an increased amount of money and possibly his life. This was the start of 10 years of correspondence.
Chanute had performed glider experiments on the sand dunes of Indiana at Lake Michigan. The brothers chose the Outer Banks of North Carolina. The winds were favorable. There was also Kill Devil Hill from which they could launch gliders.
Each autumn from 1900 to 1903, after the bicycle season, they made the long train ride from Dayton, Ohio, and a boat ride across the sound. Each year they built a new flying machine, mostly with materials they purchased en route from hardware and lumber stores. They built a shed for a shop and pitched a tent for sleeping.
Flight is fundamentally dangerous. Many risks were not well understood, winds are unpredictable, and the aircraft must be lightweight, which compromises structural strength. A necessary condition for success was not to be seriously injured or killed.
The brothers had speculated on the cause of Otto Lilien-thal’s fatal accident. They devised the prudent safety plan of staying close to the ground, taking only one step at a time, and always making control their first priority.
The first year they built a glider that they flew as a kite. A 1901 model they tried to fly as a glider had too much drag and not enough lift. Control was unacceptable.
They suspected their wing, which was based on the experiments of others. They built the worlds first wind tunnel, which allowed for more accurate lift and drag measurements than were possible with Langleys whirling arm.
Results from their wind tunnel experiments confirmed that earlier wing data overestimated the performance of various shapes. The brothers adjusted the wing’s curvature and measured substantial improvement.
Their 1902 glider used the new wing curvature. The lift-to-drag performance was much improved. They had a two-axis control that was performed by warping the wings to bank and turn, and adjusting the angle of attack on a small forward wing, or elevator, for pitch.
A left bank was initiated by warping the right wings of the biplane to increase the angle of attack and the right side lift while decreasing the angle of the left wings. It would begin a turn, but the faster-moving outer wings then had increased drag. The result was an uncoordinated turning and a possible stall.
The brothers devised a vertical rudder for positive control around the vertical, or yaw, axis. Bank and turn control would be achieved by swiveling their hips inside a movable cradle on the lower wing. Cables and pulleys connected the cradle to the rudder and outer part of the wing. A coordinated left turn began with a swivel of the hips to the left. Once started, a coordinated turn would continue. Pitch for climb or descent and thus for speed control was actuated by a hand linkage to the forward elevator.
The Wrights made several hundred successful flights in their 1902 glider, while perfecting their piloting skills.
Control around three axes with three movable sets of surfaces was an important new idea. Birds have bank and pitch control, but don’t have a movable vertical rudder. Octave Chanute immediately recognized the significance, advising the brothers to apply for a patent on their control system.
Over the next four years, Wilbur would have to personally educate the patent examiners on the principles of flight by three-axis control. The patent, finally issued under the vague title “Improvement in Flying Machines,” describes the technique now used on all aircraft.
With renewed confidence, the brothers prepared for powered flight. A single engine would power two pusher propellers via bicycle chains. The aerodynamic design of wings is challenging, but propeller design is much more complicated. By using the results of their wind tunnel tests for fixed wings, they calculated the optimal continuously variable curvature of the propeller from the root to the tip. The result was two remarkably efficient propellers.
Langley, with the help of Manly, had spent five years with government funding to successfully modify an existing engine to produce 52 hp and weigh only 130 lbs. With the improved wing performance, Wilbur calculated that only 8 hp was required for level flight. In their bicycle shop during the winter and spring of 1903, the brothers designed and built a workable 160-lb. engine that produced 16 hp when cold but deteriorated to 12 hp when hot.
The 200-cubic-inch engine contained four inline horizontal water-cooled cylinders with a 4-inch bore and stroke. There was no fuel pump, water pump, radiator, carburetor, spark plugs, or exhaust pipes. Gasoline flowed by gravity directly into the intake, where it was vaporized by incoming air. Water was allowed to boil in the jacket around the cylinders. The spark was produced by opening electric contacts inside the cylinder via a cam. Electricity was induced in a stationary coil by a magnet mounted on the 26-lb. engine flywheel.
The Wright Brothers returned in 1903 with the parts for a new flying machine and engine. The weather was bad. A major coastal storm almost destroyed them. The first attempts at powered flight failed.
On December 17, they were ready to try again, although the gusting winds were cause for concern. They laid launching rails on the sand and flipped a coin. Orville won. The engine was started. They had measured 132 lbs. of static thrust. The wing span was 40 feet and the total weight was 700 lbs. With Wilbur chasing, Orville achieved a flight of 120 feet before he lost control. Later in the day, Wilbur achieved a flight of 59 seconds and 852 feet into a 20-rnph wind.
They walked four miles to the telegraph station in Kitty Hawk. The short message to Bishop Wright in Dayton said: “Four successful flights. Will be home for Christmas.” Why did Wilbur and Orville Wright succeed instead of Samuel Langley, who as the secretary of the Smithsonian, was the nation’s most eminent scientist and had the advantages of time, government funding, and outstanding engineering support? That question is best answered by examining the five conditions that were necessary for success: adequate lift, thrust, control, flying skill, and launching.
Langley’s wings and structure were adequate in terms of lift and strength, but the Wrights had a better design. Langley had the much superior engine. The brothers had invented and implemented three-axis control. Manly had no piloting experience, while Wilbur and Orville had become highly skilled pilots with their 1902 glider. Langley’s technique of catapult launching from the roof of a houseboat was unforgiving, while the Wrights’ technique of launching with skids on the sand allowed for several initial failures and adjustments before their final success.
From Hobby to Fame
After their successful flights at Kitty Hawk, the brothers could continue treating flight as an expensive hobby or could risk their time and resources toward making it a profitable business. They chose the latter.
Over the next four years, they worked secretly at improving their flying machine and made increasingly impressive flights near Dayton while trying to sell flying machines to the U.S., French, and British governments.
In 1907, Bell re-entered aviation by forming the Aerial Experiment Association. He recruited 29-year-old Glenn Curtiss of Hammondsport, N.Y. Curtiss, raised by his mother and grandmother in the Finger Lakes wine country, was mostly self-educated and had a passion for speed.
Curtiss had made and raced bicycles and motorcycles. He also was designing a 50-hp V-8 engine for dirigibles. With one of these engines on a motorcycle he had traveled an incredible 136 mph near Daytona Beach and was duly proclaimed the fastest man on earth.
Bell had designed a large tetrahedral kite that had successfully carried a man when pulled by a high-speed boat. Bell’s plan was to install a Curtiss engine on the kite. It failed to fly because of too much drag.
Curtiss then built a machine called the Red Wing similar to the Wrights’ biplane. In March 1908, he flew it successfully by taking off from the ice on nearby Keuka Lake.
He then started the Curtiss Aeroplane Co., which led to an era of rapid progress and bitter rivalry. The Wrights sued Curtiss for patent infringement over the control system. During the succeeding years, some judges ruled in the Wrights’ favor and others supported Curtiss.
When Wilbur died of typhoid fever in 1912, Orville blamed his brother’s death on the stress that he felt had been caused by the litigation against Curtiss.
Langley’s engineer, Charles Manly, was recruited by Curtiss. Bell believed that the Langley machine, then in storage at the Smithsonian, was capable of flight. Curtiss understood that if the Langley machine could fly, it would weaken the Wrights’ patent claims.
The new Smithsonian secretary, Charles Walcott, allowed Curtiss to borrow the Langley machine. It was restored and modified. Curtiss installed floats and, in 1914, lifted the Langley machine off Keuka Lake for a flight of about 150 feet. Langley’s Folly finally flew, 11 years after its second splash in the Potomac.
The Wrights continued to contribute to the progress of aviation by starting the first flying school. They invented a flight simulator, but they never made any substantial changes to their 1903 flying machine.
Curtiss overtook them and would dominate U.S. aviation for a decade. He built several large factories. His seaplanes could cross the Atlantic by means of landing on the ocean for refueling by ships. The Curtiss Jenny became the primary U.S. primary flight trainer for World War I and then a favorite of barnstormers and stunt pilots.
Curtiss concluded that further advances in aviation would require the kind of sophisticated engineering education he did not have. He transferred his talents to designing powerboats and motorized campers and developing real estate in Florida, but he would die in 1930 at the age of 52 while still defending claims against his company. He was taken ill after five days of testifying in a courtroom in Rochester, N.Y., during a lawsuit filed by the estate of a former employee.
Meanwhile, Orville Wright was outraged at the Smithsonian for lending the Langley airplane to Curtiss. He was further offended when the Smithsonian placed Langley’s flying machine on display with a placard saying it was the first airplane capable of man-carrying flight.
The Smithsonian asked Orville to donate the 1903 machine for a parallel display, but he refused to share space with Langley’s machine. Instead, he lent the Wright Flyer to the Science Museum in London. Ironically, it was threatened by air raids during World War II and was stored in the subways for protection.
The Smithsonian finally consented to Orville’s terms. Langley’s flying machine was removed from display. On Dec. 17, 1948, the 45th anniversary of their epic flight and 11 months after Orville’s death, the Wright Flyer returned to the United States and was hung in the Arts and Sciences building.
The world’s most visited museum building is the newer Smithsonian Air and Space Museum. The first aircraft a visitor sees upon entering is the 1903 Flyer, now popularly called the Kitty Hawk. Behind it is the Spirit of St. Louis with its Wright Whirlwind engine, which Charles Lindbergh flew from New York to Paris in 1927, and the rocket plane that Chuck Yeager flew through the sound barrier in 1947. Orville finally enshrined the Kitty Hawk in its rightful place in history with the same determination and effectiveness that he and Wilbur had used to pioneer powered flight.