Tuesday, January 13, 2009

Gyroscopic Instruments: Turn Coordinator

The major limitation of the older turn-and-slip indicator is that it senses rotation only about the vertical axis of the aircraft. It tells nothing of the rotation around the longitudinal axis, which in normal flight occurs before the aircraft begins to turn.

A turn coordinator operates on precession, the same as the turn indicator, but its gimbal frame is angled upward about 30° from the longitudinal axis of the aircraft. This allows it to sense both roll and yaw. Some turn coordinator gyros are dual-powered and can be driven by either air or electricity.

Rather than using a needle as an indicator, the gimbal moves a dial on this is the rear view of a symbolic aircraft. The bezel of the instrument is marked to show wings-level flight and bank angles for a standard-rate turn. [Figure 3-34: A turn coordinator sense rotation]

The inclinometer, similar to the one in a turn-and-slip indicator, is called a coordination ball, which shows the relationship between the bank angle and the rate of yaw. The turn is coordinated when the ball is in the center, between the marks. The aircraft is skidding when the ball rolls toward the outside of the turn and is slipping when it moves toward the inside of the turn.

A turn coordinator does not sense pitch. This is indicated on some instruments by placing the words "NO PITCH INFORMATION" on the dial.

Tag: Flying instrument, instrument flight, aviation, piloting, instrument rating, instrument flying training, instrument flight rating, instrument rating requirement, instrument rating regulation, aircraft, aero plane, airplane, and aeronautical knowledge.

Tag: Types of Airspeed, Indicated Airspeed, Calibrated Airspeed, Equivalent Airspeed, True Airspeed, Mach number, Maximum Allowable Airspeed, and Airspeed Color Code.

Double gimbal: A type of mount used for the gyro in an attitude instrument. The axes of the two gimbals are at right angles to the spin axis of the gyro allowing free motion in two planes around the gyro.

Doghouse: A mark on the dial of a turn-and-slip indicator that has the shape of a doghouse.

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