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In aeronautics, spoilerons (also known as spoiler ailerons or roll spoilers) are spoilers that can be used asymmetrically as flight control surfaces to provide roll control.



Spoilerons roll an aircraft by reducing the lift of the downward-going wing. Unlike ailerons, spoilers do not increase the lift of the upward-going wing. A raised spoileron also increases the drag on the wing where it is deployed, causing the aircraft to yaw. Spoilerons can be used to assist ailerons or to replace them entirely, as in the B-52G which required an extra spoiler segment in place of ailerons present on other B-52 models. [1]


Spoilerons do not cause adverse yaw, unlike ailerons.

They are used in situations where aileron action would produce excessive wing twist on a very flexible wing or if wide-span flaps prevent adequate aileron roll control. [2]

They can also be used as spoilers.

The Mitsubishi MU-2 has double-slotted flaps that take-up the full length of the wing, to achieve good STOL performance. This leaves no room for ailerons, so it uses spoilerons instead.[ citation needed ]

Spoilerons can be used during a stall, whereas ailerons must not be used in a stall because they will have the opposite to intended effect.


Spoilerons reduce lift, increasing fuel usage. The lift reduction can be a problem in a one-engine-inoperative situation.


An early use of spoilers augmenting small ailerons, known as guide ailerons, was in the Northrop P-61 Black Widow night fighter. The spoilers allowed wider-span flaps for a lower landing speed. [3]

The B-52 Stratofortress also had spoilers augmenting small ailerons, known as feeler ailerons. These ailerons provided control forces to the pilot. The B-52G has no ailerons. The spoilers, situated inboard and forward of the trailing edge, are used for lateral control at high speeds to prevent excessive wing twist. [4]

The Mitsubishi Diamond Jet, Beechjet, and Hawker 400 family of business aircraft incorporate full length spoilerons that also double as speed spoilers during flight and landing.[ citation needed ]

Another aircraft with full-length double-slotted flaps was the Wren 460. To go with large aileron deflections at low speeds [5] it had a set of five feathering drag plates ahead of each aileron to overcome adverse aileron yaw and decrease lift on the low wing. [6]

Boeing's line of jet airliners have flight spoilers which can act as roll spoilers. They are activated automatically when the control wheel is displaced more than 10 degrees. [7]

The Tupolev Tu-154 have fast-acting spoilers. They double as spoilerons that assist the ailerons when the pilot commands a high roll rate. These can be observed in operation when the pilot is fighting gusting crosswinds while landing.[ citation needed ]


Several technology research and development efforts exist to integrate the functions of aircraft flight control systems such as ailerons, elevators, elevons, flaps, flaperons, and spoilerons into wings to perform the aerodynamic purpose with the goals of reducing 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. Expected applications include many unmanned aerial vehicles (UAVs) and sixth-generation fighter aircraft. Two promising approaches are flexible wings and fluidics.[ citation needed ]

Flexible wings

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. [8] [9] [10]


In fluidics, forces in vehicles occur via circulation control, in which larger more complex mechanical parts are replaced by smaller simpler fluidic systems (slots which emit air flows) where larger forces in fluids are diverted by smaller jets or flows of fluid intermittently, to change the direction of vehicles. [11] [12] [13] In this use, fluidics promises lower mass and costs (as little as half), very low inertia and response times, and simplicity.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Wing</span> Surface used for flight, for example by insects, birds, bats and airplanes

A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expressed as its lift-to-drag ratio. The lift a wing generates at a given speed and angle of attack can be one to two orders of magnitude greater than the total drag on the wing. A high lift-to-drag ratio requires a significantly smaller thrust to propel the wings through the air at sufficient lift.

<span class="mw-page-title-main">Fixed-wing aircraft</span> Heavier-than-air aircraft with fixed wings generating aerodynamic lift

A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft, and ornithopters. The wings of a fixed-wing aircraft are not necessarily rigid; kites, hang gliders, variable-sweep wing aircraft and airplanes that use wing morphing are all examples of fixed-wing aircraft.

<span class="mw-page-title-main">Aileron</span> Aircraft control surface used to induce roll

An aileron is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll, which normally results in a change in flight path due to the tilting of the lift vector. Movement around this axis is called 'rolling' or 'banking'.

<span class="mw-page-title-main">Stall (fluid dynamics)</span> Abrupt reduction in lift due to flow separation

In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is typically about 15°, but it may vary significantly depending on the fluid, foil, and Reynolds number.

<span class="mw-page-title-main">Flying wing</span> Tailless fixed-wing aircraft that has no definite fuselage

A flying wing is a tailless fixed-wing aircraft that has no definite fuselage, with its crew, payload, fuel, and equipment housed inside the main wing structure. A flying wing may have various small protuberances such as pods, nacelles, blisters, booms, or vertical stabilizers.

<span class="mw-page-title-main">Flight control surfaces</span> Surface that allows a pilot to adjust and control an aircrafts flight attitude

Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude.

<span class="mw-page-title-main">Elevon</span>

Elevons or tailerons are aircraft control surfaces that combine the functions of the elevator and the aileron, hence the name. They are frequently used on tailless aircraft such as flying wings. An elevon that is not part of the main wing, but instead is a separate tail surface, is a stabilator.

<span class="mw-page-title-main">Aircraft flight control system</span> How aircraft are controlled

A conventional fixed-wing aircraft flight control system (AFCS) consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight. Aircraft engine controls are also considered as flight controls as they change speed.

<span class="mw-page-title-main">Spoiler (aeronautics)</span> Device for reducing lift and increasing drag on aircraft wings

In aeronautics, a spoiler is a device which intentionally reduces the lift component of an airfoil in a controlled way. Most often, spoilers are plates on the top surface of a wing that can be extended upward into the airflow to spoil the streamline flow. By so doing, the spoiler creates a controlled stall over the portion of the wing behind it, greatly reducing the lift of that wing section. Spoilers differ from airbrakes in that airbrakes are designed to increase drag without disrupting the lift distribution across the wing span, while spoilers disrupt the lift distribution as well as increasing drag.

<span class="mw-page-title-main">Elevator (aeronautics)</span> Aircraft flight control surface

Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, and are sometimes located at the front of the aircraft or integrated into a rear "all-moving tailplane", also called a slab elevator or stabilator.

<span class="mw-page-title-main">Flap (aeronautics)</span> Anti-stalling high-lift device on aircraft

A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing distance. Flaps also cause an increase in drag so they are retracted when not needed.

<span class="mw-page-title-main">Dutch roll</span> Aircraft motion combining rolling and yawing

Dutch roll is a type of aircraft motion consisting of an out-of-phase combination of "tail-wagging" (yaw) and rocking from side to side (roll). This yaw-roll coupling is one of the basic flight dynamic modes. This motion is normally well damped in most light aircraft, though some aircraft with well-damped Dutch roll modes can experience a degradation in damping as airspeed decreases and altitude increases. Dutch roll stability can be artificially increased by the installation of a yaw damper. Wings placed well above the center of gravity, sweepback and dihedral wings tend to increase the roll restoring force, and therefore increase the Dutch roll tendencies; this is why high-winged aircraft often are slightly anhedral, and transport-category swept-wing aircraft are equipped with yaw dampers. A similar phenomenon can happen in a trailer pulled by a car.

<span class="mw-page-title-main">Radio-controlled aircraft</span> Aircraft controlled remotely via radio control

A radio-controlled aircraft is a small flying machine that is controlled remotely by an operator on the ground using a hand-held radio transmitter. The transmitter continuously communicates with a receiver within the craft that sends signals to servomechanisms (servos) which move the control surfaces based on the position of joysticks on the transmitter. The control surfaces, in turn, directly affect the orientation of the plane.

Aircraft flight mechanics are relevant to fixed wing and rotary wing (helicopters) aircraft. An aeroplane, is defined in ICAO Document 9110 as, "a power-driven heavier than air aircraft, deriving its lift chiefly from aerodynamic reactions on surface which remain fixed under given conditions of flight".

<span class="mw-page-title-main">Flaperon</span> Type of aircraft control surface that combines the functions of both flaps and ailerons

A flaperon on an aircraft's wing is a type of control surface that combines the functions of both flaps and ailerons. Some smaller kitplanes have flaperons for reasons of simplicity of manufacture, while some large commercial aircraft such as the Boeing 747, 767, 777, and 787 may have a flaperon between the flaps and aileron. The 787 has a configuration known as a SpoileFlaperon that combines the action of spoilers, flaps and ailerons into one control surface.

Adverse yaw is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll. It is caused by the difference in lift and drag of each wing. The effect can be greatly minimized with ailerons deliberately designed to create drag when deflected upward and/or mechanisms which automatically apply some amount of coordinated rudder. As the major causes of adverse yaw vary with lift, any fixed-ratio mechanism will fail to fully solve the problem across all flight conditions and thus any manually operated aircraft will require some amount of rudder input from the pilot in order to maintain coordinated flight.

In aeronautics, inertia coupling, also referred to as inertial coupling and inertial roll coupling, is a potentially catastrophic phenomenon of high-speed flight which caused the loss of aircraft and pilots before the design features to counter it were understood. It occurs when the inertia of a heavy fuselage exceeds the ability of the aerodynamic forces and movements generated by the wing and empennage to stabilize the aircraft. The problem became apparent as jet fighter aircraft and research aircraft were developed with narrow wingspans, that had relatively low roll inertia, caused by a long slender high-density fuselage, compared to the pitch and yaw inertias.

<span class="mw-page-title-main">Aircraft principal axes</span> Principal directions in aviation

An aircraft in flight is free to rotate in three dimensions: yaw, nose left or right about an axis running up and down; pitch, nose up or down about an axis running from wing to wing; and roll, rotation about an axis running from nose to tail. The axes are alternatively designated as vertical, lateral, and longitudinal respectively. These axes move with the vehicle and rotate relative to the Earth along with the craft. These definitions were analogously applied to spacecraft when the first crewed spacecraft were designed in the late 1950s.

<span class="mw-page-title-main">Leading-edge slat</span> Device increasing the lift of the wing at low speed (take-off and landing)

Slats are aerodynamic surfaces on the leading edge of the wing of a fixed-wing aircraft which, when deployed, allow the wing to operate at a higher angle of attack. A higher coefficient of lift is produced as a result of angle of attack and speed, so by deploying slats an aircraft can fly at slower speeds, or take off and land in shorter distances. They are used during takeoff and landing or while performing low speed maneuvers which may take the aircraft close to a stall. Slats are retracted in normal flight to minimize drag.

<span class="mw-page-title-main">BAE Systems Demon</span> Experimental unmanned aerial vehicle

The Demon is an experimental unmanned aerial vehicle (UAV) developed and manufactured by British defence conglomerate BAE Systems. It has been referred to as being the world's first "flapless" aircraft.


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