Flashcards in Gyroscopic Flight Instruments Deck (9)
What instruments contain gyroscopes?
a) turn coordinator
b) the heading indicator (directional gyro)
c) the attitude indicator (artificial horizon)
What are the two fundamental properties of a gyroscope?
a) Rigidity in space - a gyroscope remains in a fixed position in the plane in which it is spinning.
b) Precession - the tilting or turning of a gyro in response to a deflective force. The reaction to this force does not occur at the point where is was applied; rather, it occurs at a point that is 90 degrees later in the direction of rotation.
What are the various powers that may be used to power the gyroscopic instruments in an airplane?
In some airplanes, all of the gyros are vacuum, pressure, or electrically operated. In others, vacuum or pressure systems provide the power for the heading and attitude indicators, while the electrical system provides the power for the turn coordinator. Most aircraft have at least two sources of power to ensure at least one source of bank information if one power source fails.
How does the vacuum system operate?
An engine-driven vacuum pump provides suction which pulls air from the instrument case. Normal pressure entering the case is directed against rotor vanes to the turn the rotor (gyro) at high speed, much like a water wheel or turbine operates. Air is drawn into the instrument through a filter from the cockpit and eventually vented outside.
How does the attitude indicator work?
The gyro in the attitude indicator is mounted on a horizontal plane and depends upon rigidity in space for its operation. The horizon bar represents the true horizon. The bar is fixed to the gyro and remains in a horizontal plane as the airplane is pitched or banked about its lateral/longitudinal axis, indicated the attitude of the airplane relative to the true horizon.
How does the heading indicator work?
The operation of the heading indicator uses the principle of rigidity in space. The rotor turns in a vertical plane, and the compass card is fixed to the rotor. Since the rotor remains rigid in space, the points on the card hold the same position in space relative to the vertical plane. As the instrument case and the airplane revolve around the vertical axis, the card provides clear and accurate heading information.
The heading indicator will creep or drift from the heading to which it is set due to precession. Its important to reset the heading indicator about every 30 minutes.
How does the turn coordinator operate?
The turn part of the instrument uses precession to indicated direction and approximate rate of turn. A gyro reacts by trying to move in reaction to the force applied thus moving the needle or miniature aircraft in proportion to the rate of turn. The slip/skid indicator is a liquid filled tube with a ball that reacts to centrifugal force and gravity.
What info does the turn coordinator provide?
The turn coordinator shows the yaw and roll of the aircraft around the vertical and longitudinal axes.
The mini airplane will indicated direction of the turn as well as rate of turn. When aligned with the turn index, it represents a standard rate of turn of 3 degrees per second. The inclinometer of the turn coordinator indicated the coordination of aileron and rudder. The ball indicated whether the airplane is in coordinated flight or is in a slip or skid.