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Air brake (aeronautics)

technology Maturity 11-13 Next article →

Air brakes, also known as speed brakes, are flight control surfaces used to increase drag. Drag is a force that resists the motion of an aircraft through the air. When a pilot extends these surfaces into the airstream, they create more resistance, which slows the plane down. When they are not being used, air brakes conform to the streamlined profile of the aircraft. This helps the plane fly through the air with as little drag as possible.

CONVAIR F-106A DELTA DART Air Brake
CONVAIR F-106A DELTA DART Air Brake

It is important to distinguish between true air brakes and spoilers. Air brakes are specifically designed to increase drag while making very little change to the aircraft's lift. Spoilers work differently by reducing the lift-to-drag ratio. Using spoilers often requires a higher angle of attack to maintain lift, which results in a higher stall speed. However, on many transport aircraft, pilots and manufacturers routinely refer to flight spoilers as "speed brakes" even though they significantly reduce lift.

416th FLTS F-16 at Red Flag 12-2
416th FLTS F-16 at Red Flag 12-2

Many modern airliner jets use a combination of both spoiler and air brake controls. During the landing process, pilots deploy these spoilers, which are sometimes called "lift dumpers." This deployment causes a significant reduction in wing lift. As a result, the weight of the aircraft is transferred from the wings to the undercarriage. This increased weight improves the friction force available for the wheel brakes. The form drag created by the spoilers also assists in slowing the aircraft.

F-15 Eagle landing with the speed brake up
F-15 Eagle landing with the speed brake up

Jet-powered aircraft have different needs than propeller-driven aircraft. Propeller-driven planes benefit from a natural braking effect when the engine power is reduced to idle. Jet engines do not have this similar braking effect. Therefore, jet-powered aircraft must rely on air brakes to control their speed and descent angle during a landing approach. Some early jet models, such as the Arado Ar 234 and the Boeing B-47, used parachutes as air brakes during their approach. Other planes, like the English Electric Lightning, used parachutes to help stop after landing.

eurowings bae146-300 d-aewb arp
eurowings bae146-300 d-aewb arp

The history of these devices shows many different designs. In the early decades of powered flight, air brakes were simply flaps mounted on the wings. Pilots controlled them manually using a lever in the cockpit connected by mechanical linkages. In 1931, another type of air brake was fitted to aircraft wing support struts. In 1936, Hans Jacobs developed blade-style self-operating dive brakes for gliders. Jacobs headed the Deutsche Forschungsanstalt für Segelflug, or DFS, which was a glider research organization in Germany.

Airbrakes on Capstan
Airbrakes on Capstan

Aircraft designers have created many unique configurations for air brakes. The Blackburn Buccaneer, a naval strike aircraft designed in the 1950s, used split-tailcone air brakes. These brakes were useful because they reduced the length of the aircraft when opened, which helped in the confined spaces of an aircraft carrier. Other fighters, such as the F-15 Eagle, Sukhoi Su-27, and F-18 Hornet, have air brakes located just behind the cockpit. There is also a device called a deceleron. A deceleron is an aileron that can split in half, where the top half moves up and the bottom half moves down to create braking.

Specialized systems have also been used for unique spacecraft and advanced stealth planes. The Space Shuttle used a system where the vertically split rudder opened in a "clamshell" fashion to act as a speed brake during landing. This technique of splitting control surfaces has also been used by Northrop on several aircraft, including the B-2 Spirit. These various methods, from parachutes to split rudders, ensure that different types of aircraft can manage their energy and speed safely during all phases of flight.

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🖼️ Images & Media (6)
File:eurowings bae146-300 d-aewb arp.jpg
eurowings bae146-300 d-aewb arp.jpg
File:CONVAIR F-106A DELTA DART Air Brake.jpg
CONVAIR F-106A DELTA DART Air Brake.jpg
File:416th_FLTS_F-16_at_Red_Flag_12-2.jpg
416th_FLTS_F-16_at_Red_Flag_12-2.jpg
File:F-15 Eagle landing with the speed brake up.jpg
F-15 Eagle landing with the speed brake up.jpg
File:Airbrakes on Capstan.jpg
Airbrakes on Capstan.jpg
File:STS-116 landing port behind.jpg
STS-116 landing port behind.jpg
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