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Skid (aerodynamics)

In a straight flight, the tail of the airplane aligns the fuselage into the relative wind. However, in the beginning of a turn, when the ailerons are being applied in order to bank the airplane, the ailerons also cause an adverse yaw of the airplane. For example, if the airplane is rolling clockwise (from the pilot point of view), the airplane yaws to the left. It assumes a crab-like attitude relative to the wind. This is called a slip. The air is flowing crosswise over the fuselage. In order to correct this adverse slip, the pilot must apply rudder (right rudder in this example). If the pilot applies too much rudder, the airplane will then slip to the other side. This is called a skid.

Airplane in a right turn skid

Stall edit

The skid is more dangerous than the slip if the airplane is close to a stall. In the slip, the raised wing — the left one if the airplane is turning to the right — will stall before the lowered one, and the airplane will reduce the bank angle, which prevents the stall. In the skid, the lowered wing will stall before the raised one, and the airplane will tighten the turn, and the stall can develop to a spin.

At high altitudes, there is plenty of space for recovery. But during the final approach, when the airplane is close to the ground, a stall-spin accident is often fatal. A common cause of this accident is to enter a skidding turn in the airfield traffic pattern on the turn from base leg to final approach, unconsciously using excessive rudder in an attempt to tighten the turn and avoid overshooting the runway centreline.[1]

Deliberate skid edit

 
Turn coordinators indicating different kinds of turns

Deliberate skids are used in aerobatics and aerial combat. Deliberate slips done with vigorous application of roll and opposite rudder (lower the right wing and step on the left rudder) can be used as a dive brake. By balancing the roll's turn to the right with the rudder's yaw to the left, the plane continues to fly straight ahead but it presents its side rather than its nose to the airstream. The drag from this aerodynamically "dirty", clumsy position slows the otherwise sleek airplane. By modulating the amount of skid with rudder and aileron, the pilot can modulate the braking. Thus the plane can be slowed quickly in level flight or the descent to a landing can be dramatically steepened while holding the approach speed to a desired value.

See also edit

References edit

  1. ^ John S. Denker, See How It Flies. http://www.av8n.com/how/htm/snaps.html#sec-skids


skid, aerodynamics, straight, flight, tail, airplane, aligns, fuselage, into, relative, wind, however, beginning, turn, when, ailerons, being, applied, order, bank, airplane, ailerons, also, cause, adverse, airplane, example, airplane, rolling, clockwise, from. In a straight flight the tail of the airplane aligns the fuselage into the relative wind However in the beginning of a turn when the ailerons are being applied in order to bank the airplane the ailerons also cause an adverse yaw of the airplane For example if the airplane is rolling clockwise from the pilot point of view the airplane yaws to the left It assumes a crab like attitude relative to the wind This is called a slip The air is flowing crosswise over the fuselage In order to correct this adverse slip the pilot must apply rudder right rudder in this example If the pilot applies too much rudder the airplane will then slip to the other side This is called a skid Airplane in a right turn skid Contents 1 Stall 2 Deliberate skid 3 See also 4 ReferencesStall editThe skid is more dangerous than the slip if the airplane is close to a stall In the slip the raised wing the left one if the airplane is turning to the right will stall before the lowered one and the airplane will reduce the bank angle which prevents the stall In the skid the lowered wing will stall before the raised one and the airplane will tighten the turn and the stall can develop to a spin At high altitudes there is plenty of space for recovery But during the final approach when the airplane is close to the ground a stall spin accident is often fatal A common cause of this accident is to enter a skidding turn in the airfield traffic pattern on the turn from base leg to final approach unconsciously using excessive rudder in an attempt to tighten the turn and avoid overshooting the runway centreline 1 Deliberate skid edit nbsp Turn coordinators indicating different kinds of turnsDeliberate skids are used in aerobatics and aerial combat Deliberate slips done with vigorous application of roll and opposite rudder lower the right wing and step on the left rudder can be used as a dive brake By balancing the roll s turn to the right with the rudder s yaw to the left the plane continues to fly straight ahead but it presents its side rather than its nose to the airstream The drag from this aerodynamically dirty clumsy position slows the otherwise sleek airplane By modulating the amount of skid with rudder and aileron the pilot can modulate the braking Thus the plane can be slowed quickly in level flight or the descent to a landing can be dramatically steepened while holding the approach speed to a desired value See also editSlip aerodynamic References edit John S Denker See How It Flies http www av8n com how htm snaps html sec skids nbsp This aviation related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Skid aerodynamics amp oldid 963097230, wikipedia, wiki, book, books, library,

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