Aileron - History

History

The aileron (French for 'little wing') came into widespread use about 1915, well after the rudder and elevator flight controls. The name itself came from its usage in the French aviation journal L'Aérophile in 1908. Prior to that the control surfaces were termed in French as gouvernails horizontaux (horizontal rudders). There are many conflicting claims over who first invented the aileron and its function, roll control. From the mid-to-late 19th century, several aeronautical researchers, including Clement Ader, Charles Renard, Edson Gallaudet, Alphonse Pénaud and John Montgomery, experimented with or described the technique of wing warping, the precursor to ailerons.

In 1868, long before the advent of powered aircraft, English inventor Matthew Piers Watt Boulton patented the first aileron-type device for lateral control via 'flexed' wings. Boulton's British patent, No. 392 of 1868, issued about 35 years before ailerons were 'reinvented' and wing warping was patented, became forgotten and lost from sight until after the flight control device was in general use. If the Boulton patent had been revealed at the time of the Wright Brothers' legal filings, they may not have been able to claim priority of invention for lateral control of flying machines.

The Wright Brothers used wing warping instead of ailerons for roll control, and initially their aircraft had better flight control than aircraft that used movable surfaces. However, as aircraft became larger and heavier and aileron designs were refined it became clear that ailerons were much more effective and practical for most aircraft. Ailerons also had the advantage of not weakening the airplane's wing structure as did the wing warping technique.

New Zealander Richard Pearse reputedly made a powered flight in a monoplane that included small ailerons as early as 1902, but his claims are controversial—and sometimes inconsistent—and, even by his own reports, his aircraft were not well controlled.

Robert Esnault-Pelterie, a Frenchman, built a Wright-style glider in 1904 that used ailerons in lieu of wing warping. Although Boulton had described and patented ailerons in 1868, no one had actually built them until Esnault-Pelterie’s glider, almost 35 years later. The French journal L’Aérophile published illustrations of ailerons of Esnault-Pelterie’s glider in June 1905, and its ailerons were widely copied afterward.

In 1906 Alberto Santos-Dumont's 14-bis was modified to add interplane octagonal-planform ailerons in its outermost wing bays in November of that year, though it was never fully controllable in flight, likely due to its unconventional wing form and forward-mounted elevators and rudders.

On May 18, 1908, engineer and aircraft designer Frederick Baldwin, a member of the Aerial Experiment Association headed by Alexander Graham Bell, flew an aileron-controlled aircraft, the AEA White Wing. Wingtip ailerons were also used on the contemporary Bleriot VIII, and the 1911-vintage Curtiss Model D pusher biplane had interplane ailerons of a similar nature to those on the final form of the Santos-Dumont 14-bis. Henry Farman's ailerons on his 1909 Farman III were the first to resemble ailerons on modern aircraft, and thus have a reasonable claim as the ancestor of the modern-day aileron.

Another very late contestant included Dr. William Whitney Christmas of the U.S., who claimed (among other things) to have invented the aileron in the 1914 patent for what would become the Christmas Bullet which was built in 1918, but which proved so uncontrollable that both examples built crashed on their first flights.

Regardless of the 1868 Boulton patent and the extensive prior art created by multiple other experimenters, the Wright Brothers' Ohio patent attorney Henry Toulmin filed an expansive patent application, and on May 22, 1906 they were granted U.S. Patent 821393. The patent's importance lay in its claim of a new and useful method of controlling an airplane. The patent application included the claim for the lateral control of aircraft flight that was not limited to wing warping, but through any manipulation of the "....angular relations of the lateral margins of the airplanes .... varied in opposite directions". Thus the patent explicitly stated that other methods besides wing-warping could be used for adjusting the outer portions of an airplane's wings to different angles on its right and left sides to achieve lateral roll control.

Multiple U.S. court decisions favoured the expansive Wright patent, which the Wright Brothers sought to enforce with licensing fees starting from $1,000 per airplane, and astoundingly said to range up to $1,000 per day. According to Louis S. Casey, a former curator of the Smithsonian Air & Space Museum in Washington, D.C., and other researchers, due to the patent they had received the Wrights stood firmly on the position that all flying using lateral roll control, anywhere in the world, would only be conducted under license by them.

The Wrights subsequently became embroiled with numerous lawsuits they launched against every recalcitrant aircraft builder which used lateral flight controls (essentially all manufacturers not paying them their demanded royalties), and the brothers were consequently blamed for playing "...a major role in the lack of growth and aviation industry competition in the United States comparative to other nations like Germany leading up to and during World War I". Years of protracted legal guerrilla warfare ensued with many other aircraft builders until the United States entered World War I, when its government imposed a legislated agreement between all U.S. parties which resulted in royalty payments of only 1% to the Wrights.

Further information: Wright brothers patent war