A fly-by-wire system is one that:
Requires the pilot to stabilise the aircraft manually
Uses a system of wires connected to pulleys linked to the pilot’s controls
Converts the movements of flight controls to electronic signals that are transmitted by wires, and uses flight control computers to determine how to move the actuators at each control surface to provide the ordered response
Uses a system consisting of three gyroscopes and three accelerometers
A Shock stall is:
1. Also known as a high-speed stall
2. The breakdown in lift as the result of a shock wave
3. When an aerofoil exceeds the critical angle and there is insufficient lift to support the aircraft's weight, causing the aircraft to stall
4. Both 1 and 2 are correct
An aircraft takes off with an IAS of 200 kt and maintains the IAS to an altitude of 31,000 ft. What would the Mach number at 10,000 ft be compared to at 31,000 ft?
Lower
Higher
As subsonic flow converges, the velocity __________ and the pressure __________, while the density is said to __________.
decreases, increases, remain constant
decreases, increases, decrease
increases, decreases, remain constant
increases, decreases, decrease
As subsonic flow diverges, the velocity __________ and the pressure __________, while the density is said to __________.
decreases, increases, increase
increases, decreases, increase
As supersonic flow converges, the velocity __________ and the pressure __________, while the density and temperature is said to __________.
As supersonic flow diverges, the velocity __________ and the pressure __________, while the density and temperature is said to __________.
At what speed does the detached bow wave form?
Beyond MFS 2.0
MCRIT to 1.0
MFS 1.1–1.5
MCRIT
Coffins corner is:
When the TAS and MCRIT/MMO arrive at the same value
When the stall speed and MCRIT/MMO arrive at the same value
When the stall speed and TAS arrive at the same value
When the TAS and LSS arrive at the same value
Critical Mach number (MCRIT) is defined as:
The Mach number relative to the local speed of sound measured at a specific point on the aircraft. Depending on where this measurement is taken, this speed may be greater or less than the free-stream Mach number.
The Mach number of the airflow at a point unaffected by the pressure of the aircraft but measured relative to it
The Mach number of the airflow at a point where the drag coefficient rapidly rises. This is due to the flow separation and adverse pressure gradient behind the shock wave.
The lowest free-stream Mach number at which a local Mach number of 1.0 will occur at any point on the aircraft
For an aircraft to be laterally stable:
It must have the ability to return to normal following a stall.
It must have the ability to return to normal following a disturbance about the vertical axis.
It must have the ability to return to normal following a disturbance about the longitudinal axis.
It must have the ability to return to normal following a disturbance about the lateral axis.
How is the wingtip vortex reduced?
Winglets
Wing fences
Leading-edge sawtooth
All of these
If an aircraft were climbing at constant Mach above the tropopause, IAS would __________, and TAS would __________.
increase; decrease
decrease; remain constant
remain constant; decrease
decrease; decrease
Mach buffet is:
The decreased turbulent flow behind the shock wave. It strikes the tailplane section with enough force to buffet the controls.
An aerofoil exceeding the critical angle. The airflow breaks away from the aerofoil and strikes the tailplane.
A low-speed buffet
The increased turbulent flow behind the shock wave. It strikes the tailplane section with enough force to buffet the controls.
Mach Number is defined as:
The ratio of the indicated airspeed (IAS) to the local speed of sound (LSS)
The ratio of the calibrated airspeed (CAS) to the local speed of sound (LSS)
The ratio of the local speed of sound (LSS) to the true airspeed (TAS)
The ratio of the true airspeed (TAS) to the local speed of sound (LSS)
Select the most correct answer in regards to Mack tuck.
As an aircraft accelerates through the transonic range, the centre of pressure moves rearwards in conjunction with the aft-moving spread of supersonic flow. From a starting position of approximately 15% of the chord, the C of P may end up at 20% chord, well behind the point of maximum camber (depending on the wing). This rearward shift of the C of P increases the moment arm between the centre of pressure and the centre of gravity, causing a nose-down pitching moment.
As an aircraft accelerates through the transonic range, the centre of pressure moves forwards in conjunction with the aft-moving spread of supersonic flow. From a starting position of approximately 25% of the chord, the C of P may end up at 50% chord, well behind the point of maximum camber (depending on the wing). This forward shift of the C of P increases the moment arm between the centre of pressure and the centre of gravity, causing a nose-down pitching moment.
As an aircraft accelerates through the transonic range, the centre of pressure moves rearwards in conjunction with the aft-moving spread of supersonic flow. From a starting position of approximately 25% of the chord, the C of P may end up at 50% chord, well behind the point of maximum camber (depending on the wing). This rearward shift of the C of P increases the moment arm between the centre of pressure and the centre of gravity, causing a nose-down pitching moment.
As an aircraft accelerates through the transonic range, the centre of pressure moves rearwards in conjunction with the aft-moving spread of supersonic flow. From a starting position of approximately 5% of the chord, the C of P may end up at 70% chord, well behind the point of maximum camber (depending on the wing). This rearward shift of the C of P increases the moment arm between the centre of pressure and the centre of gravity, causing a nose-down pitching moment.
State the speed of sound formula.
38.94 × √T°K
39.84 × √T°K
38.94 × √T°C
39.84 × √T°C
The area rule states that:
The aircraft should be as large as possible.
The aircraft should be as small as possible.
The aerodynamic shape of the surface in question should change in cross-sectional area as sharply as possible, increasing rapidly to a maximum, then decreasing just as rapidly.
The aerodynamic shape of the surface in question should change in cross-sectional area as smoothly as possible, increasing gradually to a maximum, then decreasing just as gradually.
The main benefit of a sweptback wing is:
A higher critical angle
A lower critical angle
The decreased critical Mach number
The increased critical Mach number
The only thing that affects the speed of sound through the air is:
Air density
Air temperature
Air pressure
Air pollution
The speed of sound is defined as:
The distance travelled by a sound wave propagating through the air
The distance travelled by a light wave propagating through a given medium
The distance travelled by a sound wave propagating through a given medium
The distance travelled by a sound wave propagating through the water
The transonic range is typically between:
Mach 0.8 and below (approx. 530 kt)
Mach 0.8 and 1.2 (approx. 530–790 kt)
Mach 1.2 and 5.0 (approx. 790–300 kt)
Mach 5.0 and 10.0 (approx. 3,300–6,600 kt)
What does number 2 on the graph correspond to?
Critical drag rise Mach number (also known as drag divergence Mach number, or MCDR) is reached. This is the Mach number where the amount of drag experienced rapidly rises. The large increase in drag is caused by the formation of a shock wave on the upper surface of the airfoil.
The MFS reaches Mach 1.0.
MDET is reached. This is the speed where all airflow over the aircraft is supersonic. The amount of drag is slightly higher than the subsonic range due to the presence of the bow wave.
MCRIT is reached.
Wave drag is:
A form of induced drag
The drag caused by the turbulent boundary layer generated by the shock wave.
Typically seen on aircraft flying in the subsonic speed range
Typically seen on aircraft flying in the supersonic speed range
What does the number 3 correspond to on the graph?
MDET is reached, where all airflow over the wing is supersonic (>M1.0). The detached bow wave has formed and interferes with the airflow over the wing. Although a stable flow, lift is slightly reduced.
Both shock waves, above and below the wing, have reached the trailing edge. The airflow over the wing is now supersonic, and a stable laminar flow is aiding in the production of lift.
CL increases with an increase in speed. The airflow accelerates over the wing, increasing lift. MCRIT is reached where the airflow over the aircraft is now supersonic in some places
Shock waves formed above and below the wing interfere with the airflow behind the shock wave. This causes separation of the air from the wing behind the shock wave, creating drag and the reduction in lift.
What effect does increasing the angle of attack have on critical Mach number?
Reduces the critical Mach number. When you increase angle of attack, you are effectively increasing the velocity of the air over the upper section of the aerofoil. As a result, the first shock wave (normal shock wave) develops at a lower free-stream Mach number, and it is for this reason that the MCRIT is reached at a lower Mach number.
Increases the critical Mach number. When you decrease angle of attack, you are effectively increasing the velocity of the air over the upper section of the aerofoil. As a result, the first shock wave (normal shock wave) develops at a lower free-stream Mach number, and it is for this reason that the MCRIT is reached at a higher Mach number.
Reduces critical Mach number. When you increase angle of attack, you are effectively decreasing the velocity of the air over the upper section of the aerofoil. As a result, the first shock wave (normal shock wave) develops at a lower free-stream Mach number, and it is for this reason that the MCRIT is reached at a lower Mach number.
Increases the critical Mach number. When you increase angle of attack, you are effectively increasing the velocity of the air over the upper section of the aerofoil. As a result, the first shock wave (normal shock wave) develops at a lower free-stream Mach number, and it is for this reason that the MCRIT is reached at a higher Mach number.
What is the ‘crossover altitude’?
The point where the aircraft will change from climbing at constant Mach to constant IAS
Where a descending aircraft would change from constant IAS to constant Mach
The point at which a pilot would change the subscale on the altimeters from area QNH to standard 1013 hPa
Where a climbing aircraft would change from climbing at constant IAS to constant Mach
What would happen to the Mach and TAS of an aircraft descending at constant IAS below the tropopause?
Mach would decrease; TAS would decrease
Mach would increase; TAS would increase
Mach would increase; TAS would decrease
Mach would decrease; TAS would increase
Free-stream Mach number (MFS) is defined as:
Local Mach number (ML) is defined as:
Critical drag rise Mach number (MCDR) (also known as Drag Divergence Mach Number) is defined as:
Detachment Mach number (MDET) is defined as:
The Mach number where all of the airflow over the wing is supersonic. This usually occurs around MFS 1.2 to 1.3.
The Supersonic range is typically between:
Mach 1.0 to Mach 5.0 (approx. 790–3,300 kt)
What does the number 4 correspond to on the graph?
What does the number 5 correspond to on the graph?
What does the number 1 correspond to on the graph?
What does number 3 on the graph correspond to?
What does number 4 on the graph correspond to?
MCRIT is reached
If an aircraft were climbing at constant IAS above the tropopause, the Mach number would __________, and TAS would __________.
Increase, Increase
Increase, Decrease
Decrease, Decrease
Decrease, Increase
Dutch roll is characterised by __________________________________________. This is a form of oscillatory instability that is characterised by a combined rolling and yawing motion in which the rolling motion dominates.
stronger lateral stability with weaker directional stability
stronger lateral stability and strong directional stability
weaker lateral stability with stronger directional stability
weak lateral stability with weaker directional stability
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