Angle of Attack Sensor Quiz and Flashcards

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Questions and Answers

What occurs when the airflow over the wing is no longer even, but instead starts to break away and create a turbulent flow?

The airflow generates a smooth flow

The lift is destroyed (correct)

Lift peaks and then decreases

Lift increases

What is the primary purpose of the Angle of Attack (AoA) sensors in aircraft design?

To measure the airspeed

To monitor the flight attitude

To sense the angles of attack (correct)

To detect the direction of the relative wind

What is the relationship between the angle of attack and lift?

Lift always peaks at the same angle of attack

Lift is unaffected by the angle of attack

Lift increases as the angle of attack increases, up to a point (correct)

Lift decreases as the angle of attack increases

What happens to the lift when the maximum lift angle is exceeded?

Lift decreases rapidly Signup and view all the answers

At what angle of attack does a stall always occur, regardless of airspeed, flight attitude, or weight?

The critical angle of attack Signup and view all the answers

What is the typical range of maximum lift angles for most aerofoils?

Between 12° and 18° Signup and view all the answers

What is the primary reason for switching the heater element to half power when the AoA system senses the wheels are on the ground?

To prevent overheating and burning out of the element Signup and view all the answers

What is the purpose of the vibrating reed-type device in the stall warning system?

To detect low pressure at the stagnation point Signup and view all the answers

Why is it important to handle the probe-type sensor with care?

To avoid damage to the calibrated slots Signup and view all the answers

What happens to the stagnation point as the angle of attack increases?

It moves down the leading edge of the wing Signup and view all the answers

Why is it important to align and locate the AoA probes correctly during installation?

To ensure accurate angle of attack measurements Signup and view all the answers

What is the primary purpose of the stall warning system?

To provide a clear warning when the angle of attack sensor detects a critical angle of attack Signup and view all the answers

What is the primary purpose of the axial wire wound heating element in the TAT probe?

To prevent ice formation on the probe Signup and view all the answers

What is the advantage of having a pure platinum wire resistance element hermetically sealed within two concentric platinum tubes?

It ensures a close match of thermal expansion and minimisation of thermal strain Signup and view all the answers

What is the purpose of fitting covers on the TAT probe?

To ensure personnel safety and prevent insect contamination Signup and view all the answers

What is the property of a body that is a function of its temperature and is termed its emissivity?

Emissivity is the property of a body that is a function of its temperature and is termed its radiation Signup and view all the answers

What is the reason for not touching the temperature probe unless necessary?

It may be heated, and it is necessary to test for presence of heat with the back of the hand Signup and view all the answers

What is the purpose of the sensing element in the TAT probe?

To measure the temperature of the air Signup and view all the answers

What is the purpose of the AC 'bias off' voltage from the relay?

To prevent the operation of the stick-shaker motor when the aircraft is on the ground Signup and view all the answers

What happens to the sensor synchro when the aircraft is on the ground and electrical power is on?

It is supplied directly from the AC power source Signup and view all the answers

What is the effect of a reduction in temperature on the vapour in a vapour-pressure temperature indicator?

It condenses, reducing the pressure in the bulb Signup and view all the answers

What is the function of the air ground switch?

To de-energize relay K at take-off Signup and view all the answers

What type of material is nickel, as categorized by its resistance characteristics?

PTC (Positive Temperature Coefficient) Signup and view all the answers

What is the output of the demodulator when the aircraft's attitude approaches a stalled condition?

A voltage that triggers the switch SS1 to connect a 28-V DC supply direct to the stick-shaker motor Signup and view all the answers

What is the purpose of the moving-coil-type indicator in a resistance temperature system?

To display the temperature reading Signup and view all the answers

What is the purpose of the squat switch or Weight-On-Wheels (WOW) switch?

To de-energize the system when the aircraft is on the ground Signup and view all the answers

What is the effect of an increase in temperature on the resistance of a PTC material?

It increases the resistance Signup and view all the answers

What is the effect of the flap position transmitter on the signal from the angle of attack sensor?

It modifies the signal Signup and view all the answers

What is the purpose of the bulb in a resistance temperature system?

To measure the temperature Signup and view all the answers

What is the characteristic of platinum, as used in aircraft resistance thermometry?

It is manufactured to a high degree of purity and reproducibility of resistance characteristics Signup and view all the answers

Study Notes

Angle of Attack Indication

The stall angle is the angle of attack at which the airflow over the wing is no longer even, but instead starts to break away and create a turbulent flow, destroying the lift.
The Angle of Attack (AoA) is the angle between the chord line of the aerofoil and the direction of the relative wind, and is important in the production of lift.
Lift acts perpendicular to the relative wind regardless of the angle of attack.

Measuring Angle of Attack

During flight, the angle of attack is changed whenever the control column is moved forward or aft, and the coefficient of lift is changed at the same time.
As AoA increases, lift increases until it peaks (CL Max) and then decreases rapidly and the wing stalls.
For a given aircraft, a stall always occurs at the same angle of attack regardless of airspeed, flight attitude, or weight.

Angle of Attack Sensors

Angle of attack sensors have been incorporated into aircraft design to sense the angles.
Caution must be taken when handling probe-type sensors to avoid damage to the calibrated slots.
When moving the vane-type sensor, care must be taken to avoid damage to the fine movement of the transmitter shaft.

Stall Warning Systems

Stall warning systems are required in all aircraft and are designed to provide a clear warning when the angle of attack sensor detects a critical angle of attack.
A vibrating reed-type device is triggered by low pressure at the stagnation point.
The vane type is triggered by upward moving air when the stagnation point moves below the vane.

Total Air Temperature (TAT) Probes

TAT probes are sensitive items that require care when working around them.
Observe the following precautions: do not use probes as handholds, do not hang equipment on probes, fit covers for personnel safety and to stop insect contamination.

Radiation Type

The radiation emitted by any body at any wavelength is a function of the temperature of the body, termed its emissivity.

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Description

Learn about the concept of angle of attack, stall angle, and its effects on airflow over a wing. Understand the importance of angle of attack sensors in aircraft design and their role in maintaining lift.

Angle of Attack Indication in Aircraft

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