Air brake
An air brake is a flap on a vehicle that can be extended into the air flow, which increases its flow resistance and thus contributes to a significant reduction in speed.
principle
The increase in resistance brought about by an air brake can be achieved by enlarging the frontal area and by increasing the c w value . This increases the parasitic resistance . Since the laminar flow on the wing breaks behind the air brakes , the lift is also reduced.
Air brakes on aircraft
Air brakes are used in aircraft in order to reduce the airspeed at a higher angle of attack, to increase the rate of descent or to reduce the coasting distance during landing . In military aircraft, the air brake is also used for tactical maneuvers (e.g. cobra maneuvers ) or to reduce speed in a dive ( dive brake ). Air brakes are sometimes only installed on the top of the wing, sometimes on the top and bottom. They are most effective in about 25 to 45% of the wing chord and extend there vertically from the profile. When extended, they disrupt the air flow on the wing, destroy lift and create drag. They are used to avoid undesirably high speeds and, especially when landing, to increase the rate of descent and reduce the glide ratio . A special form of the spoiler is the end-edge rotary flap, in which the rear part of the profile is turned into the air flow and thus creates resistance.
Among the single-engine light aircraft , mostly only high-quality, faster, mostly turbo-charged models such as B. the Mooney M20 or the Columbia 400 an air brake. In almost all types of gliders (exception e.g. Lo 100 ) air brakes are used as a landing aid. Civilian aircraft with jet engines , however, feature spoilers (spoiler).
The airbrakes are either mechanically or hydraulically extended from the top or bottom or both sides of the wing. Airbrakes that are extended from the fuselage floor or back, or symmetrically in pairs from the fuselage side walls also occur in combat aircraft.
Air brakes on cars
In rare cases, air brakes are also installed in land vehicles, for example in the Mercedes 300 SLR and Bugatti Veyron 16.4 (dedicated air brake) and in the Mercedes-Benz SLR McLaren (rear spoiler as air brake). In the McLaren MP4-12C , which was produced from 2011 to 2014 , the rear spoiler also functions as an air brake.
Air brakes on trains
The Japanese FASTECH 360 , prototype of the high-speed train - Series E5 , had an emergency brake system with air brakes.
See also
literature
- Götsch, Ernst - Luftfahrzeugtechnik , Motorbuchverlag, Stuttgart 2003, ISBN 3-613-02006-8
- Der Segelflugzeugführer, Volume 7, Schiffmann Verlag, Bergisch Gladbach 1997, ISBN 3-921270-18-9
