Spoiler
Spoilers ( English : spoiler ) are movable flaps on the upper side of the wings of aircraft . They serve to reinforce a descent , for faster braking after landing and sometimes to support turning .
Function during descent and landing
When extending partially (symmetrically) in flight, they reduce the lift of the wings and, by worsening the glide angle, enable a descent without creating a gradient in the passenger compartment. If the angle of attack is increased, the aircraft maintains altitude and reduces speed due to the higher air resistance. In contrast to some other forms of air brakes , however, the air resistance only increases to a lesser extent.
After touching down on the runway , the spoilers are immediately fully extended in order to greatly reduce the lift of the wings and at the same time increase air resistance. Due to the immediate collapse of the lift on the wings, this measure ensures maximum loading of the landing gear wheels with the aircraft mass, so that the landing gear brakes can decelerate more. This also prevents the aircraft from “jumping” during landing.
Spoilers for aileron support
Spoilers are also used to support flight control around the longitudinal (roll) axis. To generate a rolling movement, e.g. B. to initiate the turn , the aileron of the downward wing beats upwards, that of the rising surface downwards. However, this increases the resistance of the rising wing on the outside of the curve, which leads to a negative turning moment , i.e. a yaw moment about the vertical axis that counteracts the desired direction of the curve. For this reason, some of the existing spoilers on the hanging surface are activated when turning. This has two effects: The one-sided increase in air resistance on the inside of the curve compensates for the negative turning moment and, in addition, the use of ailerons required due to the deterioration in lift of the hanging surface is reduced overall.
Types
A distinction is made between flight spoiler (the part of the spoiler flaps that is active as an air brake and for aileron support in flight, often only one or two segments on each wing side) and the ground spoiler , this is only used after touching down on the ground (mostly all existing spoiler flaps). Accidental or premature deployment of the ground spoiler in the air must be reliably prevented; usually the ground spoiler (together with the thrust reverser ) is released or automatically activated by a load sensor in the landing gear (air / ground sensor) . The sum of all spoilers is called the Speed Brake System (air brake system).
Spoilers were originally developed as dive brakes by Hans Jacobs , after losing control of the aircraft after e.g. B. To prevent entry into a cloud from exceeding the maximum airspeed in a dive, which in the thirties had cost many glider pilots their lives due to the breakage of the aircraft structure in flight.
See also
literature
- Ernst Götsch: Aircraft technology . 3. Edition. Motorbuchverlag, Stuttgart 2003, ISBN 3-613-02006-8 .