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ATPL Interview Questions - Flight deck friend Questions and Answers Fully Solved
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ATPL Interview Questions - Flight deck friend
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ATPL Interview Questions - Flight deckfriend
Why do aircraft have swept wings? - answer Swept wings delay the formation of shock
waves and aerodynamic drag.
It increases the Critical Mach number of the wing.
Wing sweep reduces the lift generated by the wing compared to a straight un-swept
wing.
What is a Critical Mach Number / MCRIT? - answer The critical mach number is the
speed at which air over the wing (or any part of the aircraft) is accelerated to speeds
above Mach 1 (the speed of sound).
How do you calculate the required sweep of the wings? - answerThe shock wave
around an aircraft becomes more acute as the speed increases.
It is essential to keep the aircraft structure within the cone-shaped shock wave known
as "the area of influence."
As long as the wing lies within the shock wave, it will operate with subsonic airflow.
The angle required to lie behind the cone increases with increasing speed.
At Mach 1.3, the angle is approximately 45 degrees, while at Mach 2.0, it is 60 degrees.
The angle of the Mach cone formed off the aircraft body at Mach 1.3 is approximately
SIN μ = 1/M (where μ is the sweep angle of the Mach cone).
What is induced drag? - answerInduced drag is the undesirable consequence of
producing lift.
Increased AOA increases Induced drag
Induced drag is a type of drag that occurs when an object in the air, such as a wing,
changes the direction of the airflow around it.
It is caused by the formation of wing tip vortices due to the pressure differential above
and below the wing, which displaces the air rearwards.
Induced drag increases with decreasing speed because the aircraft must produce more
lift at slower speeds.
,Increasing the angle of attack increases induced drag at the same rate, assuming all
other factors remain constant.
What is form drag? - answerForm drag or pressure drag arises because of the shape of
the object.
Form or pressure drag is a type of drag caused by the air flowing over an aircraft or
airfoil.
The separation of air creates turbulence and results in pockets of low and high pressure
that leave a wake behind the aircraft, opposing its forward motion.
It is also called form drag because it is caused by the shape of the aircraft.
What is parasite drag? - answerParasitic drag is drag that is caused by the aircraft
simply moving through the atmosphere.
a combination of form drag, skin friction drag and interference drag.
How do the drag components vary with speed? - answerAs an aircraft's speed
increases, induced drag decreases, but parasitic drag increases due to higher fluid
force and surface speed.
Wave drag becomes more important as speed increases into the transonic and
supersonic regimes.
The drag curve for an aircraft shows the minimum drag at a particular airspeed, which is
a compromise between various drag components.
Flying at this speed is close to the aircraft's optimal efficiency and maximises gliding
range in case of an engine failure.
To maximise gliding endurance, the aircraft's speed should be at the point of minimum
power, which occurs at lower speeds than minimum drag.
How does a wing produce lift? - answerA wing generates lift due to the shape of the
wing, angle of attack, Newton's Third Law, and conservation of momentum.
The shape of a wing creates a lower air pressure above the wing and a higher air
pressure below the wing, resulting in lift.
Newton's Third Law states that as air flows over the wing, the wing exerts a downward
force on the air, creating an equal and opposite upward force on the wing, which is the
lift.
,Conservation of momentum causes air flowing over the curved upper surface of the
wing to move faster, creating a net force upward and resulting in lift.
What is dutch roll? - answerDutch roll is a type of aircraft instability that involves rolling
and yawing oscillations.
It occurs when the dihedral effects of an aircraft are stronger than its directional stability.
This can cause the aircraft to oscillate from side to side in a rolling motion.
Yaw dampers are used to help prevent or mitigate Dutch roll.
What does a yaw dampener do? - answerThe system uses accelerometers near the tail
to measure the aircraft's yaw motion.
Signals are sent to the autopilot.
The autopilot commands the rudder servos to counteract the yaw and keep the aircraft
straight.
What are wing tip vortices? - answerWing tip vortices are caused by aircraft producing
lift and spanwise flow across the wing
High pressure air below the wing meets low pressure air above causing a vortex at the
wing tip
Winglets are used to reduce the effect and subsequent drag of wing tip vortices
Explain the area rule? - answerAccording to the rule, the drag increases in proportion to
the changes in the cross-sectional area along the length of the airplane.
What is the formula for drag? - answer
What is the centre of pressure? - answerThe Centre of Pressure (CP) is the average
location of all pressure acting on an aircraft in motion.
The CP is where the lift is considered to act through.
The position of the CP changes with different angles of attack.
What is angle of attack? - answerThe angle of attack is an aircraft's angle in relation to
the oncoming air or relative wind.
It is measured as the angle between a reference line on the aircraft, (usually the chord
line of the wing), and the oncoming air.
, What is angle of incidence? - answerangle between the chord of the wing and the
longitudinal axis of the fuselage.
What is the centre of gravity? - answerC of G is the point on the aircraft where weight
acts
C of G changes with aircraft loading and fuel burn in flight
Aft C of G results in more efficient aircraft operation and less fuel burn
Aft C of G reduces deflection of the horizontal stabilizer and lessens drag.
Name the different types of drag? - answer• Parasite Drag consisting of Form drag, skin
friction and interference drag.
• Lift-induced drag
• Wave drag
Why do shockwaves form on the aircraft? - answerShock waves occur when an object
or disturbance moves faster than the speed at which information can propagate in the
surrounding fluid.
Shock waves form when the speed of a fluid changes by more than the speed of sound.
Where do shockwaves form first? - answerIncreasing the Mach number of an aircraft
can lead to the formation of shock waves.
The first shock wave will appear on the upper surface of the wing, around the wing root.
When an aircraft exceeds the speed of sound, the shockwave forms just ahead of the
wing leading edge.
What is the purpose of flaps? - answergenerate more lift at slower airspeeds.
enable the airplane to fly at a reduced speed with a lower risk of stalling.
Flaps are especially useful during takeoff and landing.
A secondary effect of flaps is that they allow for a lower pitch attitude, giving greater
visibility to the flight crew.
What is the purpose of slats? - answerSlats and flaps change the shape of the wing
when extended
Both devices allow the wing to generate more lift
The increased lift allows the aircraft to fly at slower speeds with reduced risk of stalling
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