Skid (aerodynamics)

When sliding curve (English skid ), a curve is called in aviation, in which the slip is not parallel to the vertical axis, but inclined towards outer curve side. In most cases, therefore, the curve remote from the plane side is more strongly than the flow of the curve facing. Similarly, the lubricating curve exists ( engl. slip ), in which the slip is inclined toward the inner curve side of the airplane.

Cause of the shift curve

The reason for a sliding curve is that the airplane's longitudinal axis is not tangent to the circle to be flown (and thus the aircraft nose in the circle shows ) because the flown cross slope is too small. The pilot will be taken through an with a ball dragonfly (rarely also inclinometer ) combined turn indicator (English Turn and Bank) or - notify the thread - the glider. In the lubricating curve shows the rear of the aircraft in the circle, flown cross slope is therefore too large.

Disadvantages and risks of the shift curve

Since an aircraft flying a sliding curve, a higher air resistance experienced as a selbiges that a "clean" curve flies (ball dragonfly in the middle), the fuel consumption increases to maintain the same speed relative to the ground (English Ground Speed ​​, GS ) to be able to hold on. This is caused by the fact that the longitudinal axis of the plane is not parallel to the direction of flow, but in the direction of the curve with respect to the current lines is different (see the shift angle). Furthermore, a non- frontal flow onto Pitot Tube (also pitotsches anemometer ) leads to a false indication of the velocity relative to the surrounding air, which in turn can mislead the pilot. In extreme cases, it comes to exceed the not to be exceeded speed ( VNE ), if previously flown already in the yellow region of the airspeed indicator and increases to the original speed to maintain the pilot due to the false advertisement in a sliding curve, the engine line it at that but still comes to that the acceleration of the power increase has a higher magnitude than the negative acceleration of the increased air resistance.

Advantages of the sliding curve

Partial shift curves are deliberately flown to keep the wings as horizontal as possible, and thus the updrafts (eg, thermal) to offer a higher attack surface in a glider. But that occurring in the sliding curve retarding torque can also be used effectively to eg to slow down a glider before landing in addition (see also: sideslip ).

Adequate countermeasures

Indicating Since the ball dragonfly Turn and Bank, the direction of the apparent solder ( vectorial sum of centrifugal force ( centrifugal force) and gravity), a statement about the change to be made to the bank to get back to the "clean" turning flight are taken. In the case of the sliding curve, the pilot must increase the bank (in the direction of the curve) until the ball of the inclinometer is in the middle of the two marks, and thus is the slip at a 90 ° angle to the wing ( or forms the vertical axis of the aircraft ) and the state of a "clean" curve flight is restored. In the case of lubricating curve the pilot must reduce the bank.

• Flight maneuvers