Aileron
A much earlier aileron concept was patented in 1868 by British scientist Matthew Piers Watt Boulton, based on his 1864 paper On Aërial Locomotion.
[2][3] It first appeared in print in the 7th edition of Cassell's French-English Dictionary of 1877, with its lead meaning of "small wing".
392 of 1868, issued about 35 years before ailerons were "reinvented" in France, became forgotten and lost from sight until after the flight control device was in general use.
[12][Note 1] Gibbs-Smith stated on several occasions that if the Boulton patent had been revealed at the time of the Wright brothers' legal filings, they might not have been able to claim priority of invention for the lateral control of flying machines.
[10] Ailerons were not used on manned aircraft until they were employed on Robert Esnault-Pelterie's glider in 1904,[5][13] although in 1871 a French military engineer, Charles Renard, built and flew an unmanned glider incorporating ailerons on each side (which he termed 'winglets'), activated by a Boulton-style pendulum controlled single-axis autopilot device.
[14] The pioneering U.S. aeronautical engineer Octave Chanute published descriptions and drawings of the Wright brothers' 1902 glider in the leading aviation periodical of the day, L'Aérophile, in 1903.
This prompted Esnault-Pelterie, a French military engineer, to build a Wright-style glider in 1904 that used ailerons in lieu of wing warping.
[8][15][16] The Wright brothers used wing warping instead of ailerons for roll control on their glider in 1902, and about 1904 their Flyer II was the only aircraft of its time able to do a coordinated banked turn.
During the early years of powered flight the Wrights had better roll control on their designs than airplanes that used movable surfaces.
[17][18][19] The Wright company quietly changed its aircraft flight controls from wing warping to the use of ailerons at that time as well.
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.
[27] At the time Townsend indicated that both methods of wing warping were invented independently and were sufficiently different to each justify their own patent award.
[29] 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.
[29] The Wrights subsequently became embroiled with numerous lawsuits they launched against aircraft builders who used lateral flight controls, 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".
[28] Years of protracted legal conflict ensued with many other aircraft builders until the U.S. entered World War I, when the government imposed a legislated agreement among the parties which resulted in royalty payments of 1% to the Wrights.
Other 19th century engineers and scientists, including Charles Renard, Alphonse Pénaud, and Louis Mouillard, had described similar flight control surfaces.
Another technique for lateral flight control, wing warping, was also described or experimented with by several people including Jean-Marie Le Bris, John Montgomery, Clement Ader, Edson Gallaudet, D.D.
An unwanted side effect of aileron operation is adverse yaw—a yawing moment in the opposite direction to the roll.
Later examples brought the counterbalance in line with the wing to improve control and reduce drag.
The size of the spade (and its lever arm) determines how much force the pilot needs to apply to deflect the aileron.
These balance weights are tear drop shaped (to reduce drag), which make them appear quite different from spades, although both project forward and below the aileron.
[34] During the 1930s a number of light aircraft used single acting controls but used springs to return the ailerons to their neutral positions when the stick was released.
Used on the first-ever airframe to have the combination of "joystick/rudder-bar" controls that directly led to the modern flight control system, the Blériot VIII in 1908,[35] some designs of early aircraft used "wingtip" ailerons, where the entire wingtip was rotated to achieve roll control as a separate, pivoting roll-control surface—the AEA June Bug used a form of these, with both the experimental German Fokker V.1 of 1916 and the earlier versions of the Junkers J 7 all-duralumin metal demonstrator monoplane using them—the J 7 led directly to the Junkers D.I all-duralumin metal German fighter design of 1918, which had conventionally hinged ailerons.
Engineer Leslie George Frise (1897–1979) of the Bristol Aeroplane Company[37] developed an aileron shape that is pivoted at about its 25 to 30% chord line and near its bottom surface [1], in order to decrease stick forces as aircraft became faster during the 1930s.
Both the Canadian Fleet Model 2 biplane of 1930 and the 1938 popular US Piper J-3 Cub monoplane possessed Frise ailerons as designed and helped introduce them to a wide audience.
[40] This helps reduce the likelihood of a wing tip stall when aileron deflections are made at high angles of attack.
This had the disadvantages of stressing the structure, being heavy on the controls, and of risking stalling the side with the increased angle of attack during a maneuver.
