Aerodynamics Flashcards
When an aircraft is rolled, what force is inclined?
Lift
Lift is always perpendicular to the direction of what?
Relative airflow
During a roll, the aircraft is pulled sideways. What is the name for this effect and what is the cause?
Sideslip resulting from the lift being inclined to one side.
What is the secondary effect of a roll and why?
Yaw due to loss of lift resulting in sideslipping which pushes the tail sideways into the air
What is the primary effect of using rudder?
Yaw
What is the secondary effect of applying rudder and why?
Roll because the rudder creates a yaw that increases relative airflow over the wing on the outer side of the turn.
What is the term used to specify the degree of cross sectional curvature of a wing.
Camber
What is the typical critical angle (in degrees)?
15 to 16
What is the name of the type of drag that is greatest at low IAS?
Induced drag
The trim control is used to provide what?
Aerodynamic balance
Flutter of control surfaces is prevented by what?
A mass balance that brings centre of mass of the control surface closer to the hinge.
During takeoff, should flaps be used?
Flaps are used according to manufacturer specifications
What is Vx used to represent and what is the value in a Jabiru J160?
Speed of climb in a max angle climb -60Kts
In a Jabiru J160, what is Vy (max rate climb speed) in Kts?
80
What does VSI stand for?
Vertical speed indicator
Performance is determined by what and what?
Power and Attitude
Lift divided by weight is called what?
Load factor
Stall speed increases by what function of an increased load factor?
The Square root
In a level flight bank, what happens to the load?
Lift has to increase to compensate for being inclined so that the load factor also increases
Turn performance is related to what and what?
Angle of bank and IAS
The lift equation ( CL . 1/2 . Density . V^2 . S ). CL is related to what two properties?
Angle of attack and camber
A slipping right turn (analogous to understeer in a car) causes the balance ball to drift to which side?
Right
A skidding turn (analogous to oversteer in a car) sees the balance ball pushed to which side of the turn? (Outside or inside)
Outside
If the aircraft is skidding when turning should more or less rudder be applied?
Less
If an aircraft is carrying luggage that has been stowed such that shifts the centre of gravity to the aft, will the stalling speed increase or decrease?
Increase
What happens to the angle of attack when a wing encounters a thermal updraft?
It increases as the air is approaching the aircraft from below
If one wing stalls, it may cause the aircraft to roll. The downwards motion of that wing relative to the air increases its angle of attack. What is the term for effect this has on the stall?
Aggravating the stall
Why should ailerons never be used in a stall?
They increase the drag
What control input is used in a stall?
Rudder
What is the correct response to a spin?
Throttle to idle, apply opposite rudder, lower the nose, apply full power to recover lost altitude
How can a pilot distinguish between a spiral dive and a spin?
If the indicated airspeed is low, the aircraft is in a spin. If it’s high, the aircraft is in a spiral dive.
A dynamic accelerated stall is also known as a what? Why might this occur?
High speed stall. Beyond the critical angle a stall will occur regardless of speed.
Beyond the critical angle, is there a speed that can prevent a stall
No
With a faster airspeed the radius of a turn is what
Increased
What is worst for a small aircraft when a nearby larger aircraft is flying slowly, taking off or landing or is flying on a clam day?
Wake turbulence
When taking off after a larger aircraft, you should lift off where (relative to the larger aircraft’s liftoff point)
Before
To avoid wake during a landing after a larger plane, where should the pilot of a small aircraft aim?
Beyond the larger aircraft’s touchdown point.
What is the term for the ratio of the span of a wing to its chord?
Aspect ratio
During a takeoff run, slipstream, torque and gyroscopic effect combine to cause the aircraft to tend to do what?
Yaw to the left
Why is the tail raised in a tail wheel aircraft during the takeoff roll?
To get clear air over the rudder
In most aircraft, which is further aft, the centre of pressure (CoP) or the centre of gravity (CoG)?
CoP
The location of the centres of pressure and gravity usually cause a nose down tendency which is countered by the placement of what above what?
Drag above thrust
Takeoff performance is measured in terms of what?
Distance required for takeoff
IAS measures the what of the air?
Dynamic pressure
Is true airspeed greater than or less than Indicated airspeed?
Greater
Wind from 45 degrees to the left and rear is a what sort of tailwind?
Left quartering
What aileron and stick control is used to counter a right quartering tailwind?
Left aileron and forward stick
Trim is adjusted to hold a constant what?
Pitch
What two factors determine the size of a moment?
Force and distance
Is lift reduced during a roll?
No but it is inclined so that its verticle component is reduced
What is the lift equation?
Lift = CL . 1/2 . Density . V^2 . S
In the lift equation, what is S
Wing surface area
The equivalent of understeer in a car is a what sort of aircraft turn?
Slipping
During a turn, if the aircraft yaws too much, the turn is called what?
Skidding turn
What does Vy stand for?
Max rate climb speed
How is load factor defined
Lift/weight
How does load factor impact on stall speed?
As load factor increases, stall speed increases by its square root
How does a thermal updraft impact on the likelihood of a stall?
The updraft increases the angle of attack as air is now rising. This increases the risk of a stall and may also be uneven, causing one wing to stall, resulting in a potential spin.
Flaps allow a pilot to take a descent path that is what?
Steeper
How does aspect ratio relate to drag?
High aspect ratios are associated with lower induced drag (think of glider wings)
Which of the following is caused by propeller slipstream?
Yaw, Roll or Pitch?
Yaw
What is the correct response in a spiral dive?
Opposite aileron to level the wings
When pressure height is less than elevation, what can you say anout QNH?
It is more than 1013mb
In a steady climb what can you say about thrust, drag, weight and lift?
The lift is less than weight as the AoA means thrust has to exceed drag and the excess combines with lift to overcome weight.
Under the recency rules, to carry passengers, what mut an RPL holder have done?
Conducted 3 takeoffs and landings in the past 90 days
As a student pilot if you cannot fly for 6 weeks who can certify you to recommence flying?
Your DAME
What are ASI, AH, DG and T&P?
Airpeed indicator
Artificial Horizon
Directional Gyro
Turn and Balance indicator
What are the gyro instruments?
DG
AH
T&B
Attitude indicator is otherwise known as what?
AH
Does a failure of the suction system affect the DG?
Yes - the gyro is suction driven and the DG relies on the gyro.
What are the pressure instruments?
Airspeed indicator
Altimeter
VSI
What angle of attack gives least drag?
4 degrees
A TAF indicates wind direction from true or magnetic?
True
On a bravo loading chart, the climb weight limit must be condidered. Why?
You may need to use that rather than the takeoff weight limit.
In a climb is weight greater than, equal to or less than lift?
Greater
What is the name for the maximum speed at which full deflection of a control surface will not stress the airframe?
Manoeuvre speed
Which primary controls are more effective with greater airspeed?
All three
What is the formula for load factor increase in a bank?
(Original load factor)/cos(angle)
How much is the stall speed increased in a 30, 45, 60, 75 degree bank?
7%, 20%, 40%, 100%
How does the stall IAS vary with altitude?
It doesn’t
How does an increased AoA affect centre of pressure?
It is shifted forward
How can you approximate glide range?
Lift:drag ratio x altitude
A plane cannot enter a spin unless it is allowed to what?
Stall
In an engine failure just after takeoff what is the first task?
Lower the nose to maintain speed
How does an increased AoA affect centre of pressure?
It is shifted forward
How can you approximate glide range?
Lift:drag ratio x altitude
A plane cannot enter a spin unless it is allowed to what?
Stall
In an engine failure just after takeoff what is the first task?
Lower the nose to maintain speed
Runways are denoted by
A) magnetic or
B) true
Direction?
A
What causes an aggravated stall?
If one wing stalls it may fall, increasing its AoA. This can lead to a spiral dive
What are two names for a stall that occurs when the IAS is high?
High speed stall
Dynamic accelerated stall
What are conditions that can create the most likelihood of wake turbulence behind a large aircraft?
When it takes off or lands or flies slowly on a calm day
