turn indicator(redirected from Slip-skid indicator)
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an aircraft gyroscopic device that indicates the deviation of an aircraft from a straight-line course.
A turn indicator is based on the ability of a gyroscope with two degrees of freedom to superpose the angular velocity vector of the gyroscopic rotor’s own spin and the angular velocity vector of the rotation of the device’s case. The spin axis of a turn indicator’s rate gyroscope is horizontal and at a right angle to the fore and aft axis of the aircraft; the axis of the gimbal in which the rotor spins is parallel to the longitudinal axis of the aircraft. Unlike a compass, a turn indicator responds only during a turn. The angle of deviation of the gyroscopic gimbal and the pointer connected to it depends on the aircraft’s turn rate. (See alsoGYROSCOPE.)