Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector. The two ailerons are typically interconnected so that one goes down when the other goes up: The downgoing aileron increases the lift on its wing while the upgoing aileron reduces the lift on its wing, producing a rolling moment about the aircraft's longitudinal axis. The word ''aileron'' is French for "little wing".

An unwanted side effect of aileron operation is adverse yaw—a yawing moment in the opposite direction to the roll. Using the ailerons to roll an aircraft to the right produces a yawing motion to the left. As the aircraft rolls, adverse yaw is caused primarily by the change in drag on the left and right wing. The rising wing generates increased lift, which causes increased induced drag. The descending wing generates reduced lift, which causes reduced induced drag. The difference in drag on each wing produces the adverse yaw. There is also often an additional adverse yaw contribution from a difference in profile drag between the up-aileron and down-aileron.

Adverse yaw is effectively compensated by the use of the rudder, which results in a sideforce on the vertical tail that opposes the adverse yaw by creating a favorable yawing moment. Another method of compensation is ''differential ailerons'', which have been rigged such that the downgoing aileron deflects less than the upgoing one. In this case the opposing yaw moment is generated by a difference in profile drag between the left and right wingtips. ''Frise ailerons'' accentuate this profile drag imbalance by protruding beneath the wing of an upward-deflected aileron, most often by being hinged slightly behind the leading edge and near the bottom of the surface, with the lower section of the leading edge protruding slightly below the wing's undersurface when the aileron is deflected upwards, substantially increasing profile drag on that side. Ailerons may also be designed to use a combination of these methods.

With ailerons in the neutral position, the wing on the outside of the turn develops more lift than the opposite wing due to the variation in airspeed across the wing span, which tends to cause the aircraft to continue to roll. Once the desired angle of bank (degree of rotation on the longitudinal axis) is obtained, the pilot uses opposite aileron to prevent the angle of bank from increasing due to this variation in lift across the wing span. This minor opposite use of the control must be maintained throughout the turn. The pilot also uses a slight amount of rudder in the same direction as the turn to counteract adverse yaw and to produce a "coordinated" turn wherein the fuselage is parallel to the flight path. A simple gauge on the instrument panel called the slip indicator, also known as "the ball", indicates when this coordination is achieved.

History

The aileron came into widespread use well after the rudder and elevator. The Wright Brothers used wing warping instead of ailerons for roll control, and initially, their aircraft had much better control in the air than aircraft that used movable surfaces; however, as aileron designs were refined, and aircraft became larger and heavier, it became clear that they were much more effective and practical for most aircraft.

There are conflicting claims over who first invented the aileron. In 1868, 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 patent, No. 392, awarded in 1868 some 40 years before ailerons were 'reinvented', became forgotten until the aileron was in general use. If the Boulton device had been revealed at the time of the Wright Brother's patent filings, they may not have been able to claim priority of invention for lateral control of flying machines.

New Zealander Richard Pearse may have 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 40 years later.

The 14 Bis airplane, by Santos Dumont, was modified to add ailerons in late 1906, though it was never fully controllable in flight, likely due to its unconventional wing form.

Henry Farman's ailerons on the ''Farman III'' were the first to resemble ailerons on modern aircraft, and have a reasonable claim as the ancestor of the modern aileron.

In 1908 U.S. inventor, businessman and engine builder Glenn Curtiss flew an aileron-controlled aircraft. However Curtiss had previously been a member of the Aerial Experiment Association, headed by Alexander Graham Bell. The Association had previously developed ailerons for their aircraft. The AEA members were later dismayed when Curtiss dropped out of their organization, patented their innovation and reportedly sold the patent to the United States Government.

Another contestant includes Dr. William Whitney Christmas of the U.S., who claimed to have invented an aileron in the 1914 patent for what would become the Christmas Bullet, which was built in 1918.

Aileron spades

These are flat metal plates, usually attached to the aileron lower surface, ahead of the aileron hinge, by a lever arm. They reduce the force needed by the pilot to deflect the aileron and are often seen on aerobatic aircraft. As the aileron is deflected upward, the spade produces a downward aerodynamic force, which tends to rotate the whole assembly so as to further deflect the aileron upward. The size of the spade (and its lever arm) determine how much force the pilot needs to apply to deflect the aileron.

Aileron balance weights

To prevent control surface flutter (aeroelastic flutter), the center of lift of the control surface should be behind the center of gravity of that surface. To achieve this, lead weights may be added to the front of the aileron. In some aircraft the aileron construction may be too heavy to allow this system to work without huge weight increases. In this case, the weight may be added to a lever arm to move the weight well out in front to the aileron body. These balance weights are tear drop shapes (to reduce drag), which make them appear quite different from spades, although both project forward and below the aileron.

Types of ailerons

Frise Ailerons

Engineer Leslie George Frise (1897–1979) developed an aileron shape that is often used due to its ability to counteract adverse yaw. The Frise aileron is pivoted at about its 25 to 30% chord line and near its bottom surface. When the aileron is deflected up (to make its wing go down), the leading edge of the aileron dips into the airflow beneath the wing. The moment of the leading edge in the airflow helps to move up the trailing edge, decreasing the stick force. The down-moving aileron also adds energy to the boundary layer by the airflow from the under-side of the wing that scoops air by the edge of the aileron that follows the upper surface of the aileron and creates a lifting force on the upper surface of the aileron aiding the lift of the wing. That reduces the needed deflection angle of the aileron. If the leading edge of the aileron is sharp or bluntly rounded, that adds significant drag to that wing and help the aircraft to yaw (turn) in the desired direction, but adds some unpleasant or potentially dangerous aerodynamic vibration (flutter).

Differential ailerons

By careful design of the mechanical linkages, the up aileron can be made to deflect more than the down aileron (e.g., US patent 1565097). This helps reduce the likelihood of a wing tip stall when aileron deflections are made at high angles of attack. The idea is that the loss of lift associated with the up aileron carries no penalty while the increase in lift associated with the down aileron is minimized. The rolling couple on the aircraft is always the difference in lift between the two wings.

The de Havilland Tiger Moth classic British biplane is one of the best-known aircraft, and one of the earliest, to use differential ailerons.

Combinations with other control surfaces

A control surface that combines an aileron and flap is called a ''flaperon''. A single surface on each wing serves both purposes: Used as an aileron, the flaperons left and right are actuated differentially; when used as a flap, both flaperons are actuated downwards. When a flaperon is actuated downward (i.e., used as a flap), there is enough freedom of movement left to be able to still use the aileron function.

A further form of roll control, common on modern jet transport aircraft, utilises spoilers in conjunction with ailerons. This is called a ''spoileron''.

In a delta-winged aircraft, the ailerons are combined with the elevators to form an ''elevon''.

Several modern fighter aircraft may have no ailerons on the wings at all, and combine roll control with an all moving tailplane. This is a ''stabilator'' or a rolling tail.

Research

Several technology research and development efforts exist to integrate the functions of aircraft flight control systems such as ailerons, elevators, elevons, flaps, and flaperons into wings to perform the aerodynamic purpose with the advantages of less: mass, cost, drag, inertia (for faster, stronger control response), complexity (mechanically simpler, fewer moving parts or surfaces, less maintenance), and radar cross section for stealth. These may be used in many unmanned aerial vehicles (UAVs) and 6th generation fighter aircraft. Two promising approaches are flexible wings, and fluidics.

In flexible wings, much or all of a wing surface can change shape in flight to deflect air flow. The X-53 Active Aeroelastic Wing is a NASA effort. The Adaptive Compliant Wing is a military and commercial effort.

In fluidics, forces in vehicles occur via circulation control, in which larger more complex mechanical parts are replaced by smaller simpler fluidic systems (slots that emit air flows) where larger forces in fluids are diverted by smaller jets or flows of fluid intermittently, to change the direction of vehicles. In this use, fluidics promises lower mass, costs (up to 50% less), and very low inertia and response times, and simplicity.

See also

Aircraft flight control system

Trailing edge

Flaperon

References

External links

NASA Glenn Research Center aileron article with Java demo and more pictures

Category:Aircraft controls Category:Wing design Category:French loanwords Category:Alexander Graham Bell

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name	Easy Star All-Stars
landscape	yes
background	group_or_band
origin	Jamaica/USA
genre	Reggae, ska, dub
years active	2003–present
label	Easy Star
website	http://www.easystar.com/
current members	Michael GoldwasserVictor Axelrod aka TicklahPatrick DougherVictor Rice
past members	}}

Originally formed as a studio band for the label's earliest recordings, Easy Star All-Stars is a reggae collective with a rotating roster of musicians and singers founded by the co-founders (Michael Goldwasser, Eric Smith, Lem Oppenheimer & Remy Gerstein) of New York City-based Easy Star Records in 1997. Although they have backed many artists and produced several original releases, they are best known for covering popular albums in a reggae and dub style and have released three cover albums to date. The first, released in 2003, was an interpretation of Pink Floyd's classic ''The Dark Side of the Moon'' entitled ''Dub Side of the Moon''; the second was 2006's ''Radiodread'', a song-by-song cover of Radiohead's ''OK Computer''. In March 2008 they released an EP consisting mostly of non-cover material. In April 2009, they released a cover of The Beatles' ''Sgt. Pepper's Lonely Hearts Club Band'' entitled ''Easy Star's Lonely Hearts Dub Band''. On 5 April 2011, they released their first original album entitled First Light.

History

In February 2003, Easy Star All-Stars released a cover album of Pink Floyd's ''The Dark Side of the Moon'' entitled ''Dub Side of the Moon'', a complete reggae reinterpretation of the Pink Floyd album. ''Dub Side of the Moon'' has remained on the Billboard Reggae Charts since its release in 2003. It features instructions on how to synchronize the record with ''The Wizard of Oz'', referencing the audiovisual pairing sometimes referred to as ''Dark Side of the Rainbow''.

''Dub Side of the Moon'' was followed by the 2006 release of ''Radiodread'', a reimagining of Radiohead's album ''OK Computer''. At a 2006 Radiohead concert, Thom Yorke praised Toots & The Maytals version of "Let Down" on ''Radiodread'' "in a rare moment of onstage chatter." Radiohead guitarist Jonny Greenwood has also praised the song, calling it "truly astounding."

In March 2008 Easy Star All-Stars released ''Until that Day'', an EP consisting of original material except for "Dubbing Up the Walls", a cover of the Radiohead song "Climbing Up the Walls."

On January 13, 2009 the Easy Star All-Stars posted a statement on their website that they had completed their next album, a reworking of ''Sgt. Pepper's Lonely Hearts Club Band'' by The Beatles titled ''Easy Star's Lonely Hearts Dub Band'', which was released on April 14, 2009. However it was exclusively released on imeem a day prior. Reviews have been favourable. Sydney street press Music Feeds rated the album 10/10. ''Easy Star's Lonely Hearts Dub Band'' cracked the Billboard Top 200 twice, making it the first reggae album to do so in over two years.

Victor Axelrod aka Ticklah compiled a dub version of a song by the Iowa reggae band Public Property on an upcoming album ''Work to Do'' set for release in July 2009.

Michael Goldwasser compiled a dub version of the song "Turn & Run" by Umphrey's McGee.

In October 2010, the Easy Star All-Stars will release ''Dubber Side of the Moon'', featuring bass-heavy remixes of ''Dub Side of the Moon'' by Dubmatix, 10 Ft. Ganja Plant, Groove Corporation, Dubphonic, The Alchemist, Dreadzone, Kalbata, Adrian Sherwood & Jazzwad, Victor Rice, Border Crossing, Mad Professor, Michael G. & Easy Star All-Stars, and J. Viewz.

Current line-up

Listed in the order and as they appear in the liner notes accompanying ''Dub Side of the Moon'':

Michael Goldwasser

Victor Axelrod aka Ticklah

Patrick Dougher

Victor Rice

The core of the touring line-up has remained largely intact since 2003. The rotating roster includes:

Ras I Ray (bass, vocals)

Ive-09 (drums)

Kirsty Rock (vocals)

Jenny Hill (saxophone, flute)

Buford O'Sullivan (trombone)

Menny More (DJ vocals)

Elenna Canlas (keyboards, vocals)

Shelton Garner, Jr. (guitar, vocals)

Cliff Simpson (drums)

Joanne Williams (vocals)

Discography

''Dub Side of the Moon'' - (2003)

''Radiodread'' - (2006)

''Until that Day'' EP - (2008)

''Easy Star's Lonely Hearts Dub Band'' - (2009)

''Dubber Side of the Moon'' - (2010)

''First Light'' - (2011)

References

External links

Easy Star Records

Myspace Blog

Easy Star All-Stars, Camden Koko (28/04/2009) Live Review at DailyMusicGuide.com

Easy Star All-Stars|Cover band musical groups Category:Living people Category:Reggae musical groups

es:Easy Star All-Stars fr:Easy Star All-Stars it:Easy Star All-Stars hu:Easy Star All-Stars nl:Easy Star All-Stars