Flight Instruments Flashcards
How does the Vertical Speed Indicator work?
The VSI is an instrument which indicates deviation from a constant pressure level
The wafer and the casing are vented to the static system but the case is vented through a calibrated orifice that causes the pressure to change slower than the pressure in the wafer allowing it to indicate a rate of climb or rate of descent
When we climb the wafer expands. When we descend the wafer is compressed. This is registered through gears that move the pointer of the VSI
What are the errors of the ASI?
Position error: erroneous static pressure causing plus or minus value
Density error: changes in altitude and temperature aren’t compensated by the instrument
Compressibility error: packed air in pitot tube resulting in higher indications
What are the Attitude indicator erros?
If we exceed the banking and pitching limits the instrument will tumble and spill and give incorrect indications
What are the Vertical Speed Indicator Errors?
The instrument lags
turbulence may cause airflow fluctuations and erroneous readings
How does the Airspeed Indicator work?
The ASI is an instrument that indicates dynamic pressure
there’s a wafer that compresses or expands due to pressure forces from the pitot tube and the casing is receiving pressure from the static port
The difference is registered by the airspeed pointer through gears that move the pointers of the ASI
How does the attitude indicator work?
It is a gyroscopic instrument operating on the principle of rigidity in space.
An engine driven vacuum pump provides suction pulling air from the case which spins the gyro at a high speed.
The horizontal mounted gyro remains fixed on a set of gimbals as the airplane moves around it. The horizon bar is fixed to the gyro and it indicates the attitude of the airplane
What are the Altimeter errors?
On a warm day, the pressure level is higher than standard and the instrument indicates lower
On a cold day, the pressure level is lower than standard and the instrument indicates higher
When the pressure level is higher than standard, the altimeter indicates lower
When the pressure level is lower than standard the altimeter indicates higher
What are the Heading Indicator errors?
if we exceed the banking and pitching limits the instrument will tumble and spill and give incorrect indications. we may reset the instrument with a knob
How Does the Magnetic Compass Work?
It’s a simple magnetic bar suspended in fluid.
The magnets align with the Earth’s magnetic field and the pilot reads the direction on the scale opposite the lubber line
How does the Turn Coordinator operate?
The turn part of the instrument uses precession to indicate direction and approximate rate of turn.
A gyro reacts by trying to move in reaction to the force applied thus moving the miniature aircraft in proportion to the rate of turn
The slip skid indicator or inclinometer is a liquid filled tube with a ball that reacts to centrifugal force and gravity.
How does the Heading Indicator work?
It is a gyroscopic instrument operating on the principle of rigidity in space.
An engine driven vacuum pump provides suction pulling air from the case which spins the gyro at a high speed.
The vertical mounted gyro remains fixed on a set of gimbals as the airplane moves around it. The compass card is fixed to the gyro and it indicates accurate heading information
How does the Altimeter work?
This instrument measures absolute pressure
The wafer inside the casing is reacting to the atmospheric pressure received by the static port.
When we climb the pressure is low and the wafer expands, when we descend the pressure is higher and the wafer contracts
Because the pressure at any given point does not stay the same the pilot can set the current atmospheric pressure by setting the current pressure reading in the kolsman window. This realigns the gears inside the instrument allowing the pointers to indicate the altitude
