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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?
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?
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?
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?
What happens to the lift when the maximum lift angle is exceeded?
At what angle of attack does a stall always occur, regardless of airspeed, flight attitude, or weight?
At what angle of attack does a stall always occur, regardless of airspeed, flight attitude, or weight?
What is the typical range of maximum lift angles for most aerofoils?
What is the typical range of maximum lift angles for most aerofoils?
What is the primary reason for switching the heater element to half power when the AoA system senses the wheels are on the ground?
What is the primary reason for switching the heater element to half power when the AoA system senses the wheels are on the ground?
What is the purpose of the vibrating reed-type device in the stall warning system?
What is the purpose of the vibrating reed-type device in the stall warning system?
Why is it important to handle the probe-type sensor with care?
Why is it important to handle the probe-type sensor with care?
What happens to the stagnation point as the angle of attack increases?
What happens to the stagnation point as the angle of attack increases?
Why is it important to align and locate the AoA probes correctly during installation?
Why is it important to align and locate the AoA probes correctly during installation?
What is the primary purpose of the stall warning system?
What is the primary purpose of the stall warning system?
What is the primary purpose of the axial wire wound heating element in the TAT probe?
What is the primary purpose of the axial wire wound heating element in the TAT probe?
What is the advantage of having a pure platinum wire resistance element hermetically sealed within two concentric platinum tubes?
What is the advantage of having a pure platinum wire resistance element hermetically sealed within two concentric platinum tubes?
What is the purpose of fitting covers on the TAT probe?
What is the purpose of fitting covers on the TAT probe?
What is the property of a body that is a function of its temperature and is termed its emissivity?
What is the property of a body that is a function of its temperature and is termed its emissivity?
What is the reason for not touching the temperature probe unless necessary?
What is the reason for not touching the temperature probe unless necessary?
What is the purpose of the sensing element in the TAT probe?
What is the purpose of the sensing element in the TAT probe?
What is the purpose of the AC 'bias off' voltage from the relay?
What is the purpose of the AC 'bias off' voltage from the relay?
What happens to the sensor synchro when the aircraft is on the ground and electrical power is on?
What happens to the sensor synchro when the aircraft is on the ground and electrical power is on?
What is the effect of a reduction in temperature on the vapour in a vapour-pressure temperature indicator?
What is the effect of a reduction in temperature on the vapour in a vapour-pressure temperature indicator?
What is the function of the air ground switch?
What is the function of the air ground switch?
What type of material is nickel, as categorized by its resistance characteristics?
What type of material is nickel, as categorized by its resistance characteristics?
What is the output of the demodulator when the aircraft's attitude approaches a stalled condition?
What is the output of the demodulator when the aircraft's attitude approaches a stalled condition?
What is the purpose of the moving-coil-type indicator in a resistance temperature system?
What is the purpose of the moving-coil-type indicator in a resistance temperature system?
What is the purpose of the squat switch or Weight-On-Wheels (WOW) switch?
What is the purpose of the squat switch or Weight-On-Wheels (WOW) switch?
What is the effect of an increase in temperature on the resistance of a PTC material?
What is the effect of an increase in temperature on the resistance of a PTC material?
What is the effect of the flap position transmitter on the signal from the angle of attack sensor?
What is the effect of the flap position transmitter on the signal from the angle of attack sensor?
What is the purpose of the bulb in a resistance temperature system?
What is the purpose of the bulb in a resistance temperature system?
What is the characteristic of platinum, as used in aircraft resistance thermometry?
What is the characteristic of platinum, as used in aircraft resistance thermometry?
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.