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Flashcards in Aerodynamics Deck (69)
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0
Q

What is due to the weight of the air molecules in the atmosphere?

A

Static pressure

1
Q

As air accelerates, what happens to static and dynamic pressure?

A

Static decreases and dynamic increases

2
Q

Dynamic pressure is due to?

A

Relative movement

3
Q

What is the formula for dynamic pressure?

A

1/2pvsquared

4
Q

The point on the aero foil at which streamlined, laminar flow become turbulent is know as the ?

A

Transition point

5
Q

The point on the aerofoil at which turbulent flow separates is know as the?

A

Separation point

6
Q

A well chambers aerofoil will produce lift at 0 degrees angle of attack, true or false?

A

True

7
Q

A symmetrical aerofoil will produce no lift at 0degrees angle of attack true or false?

A

True

8
Q

What is the point where lift is assumed to act?

A

Centre of pressure

9
Q

The chord line is a straight line which?

A

Joins the leading and trailing edge

10
Q

At a high angle of attack most of the loft on an aerofoil is produced where?

A

Leading edge

11
Q

As angle of attack is increased up to critical angle, what happens to the centre of pressure?

A

Moves forward

12
Q

When the critical angle is exceeded, what happens to the centre of pressure?

A

It moves aft

13
Q

Thrust stream turbulence varies with?

A

Engine power and distance from the source

14
Q

Which flight condition of a large jet would create the most severe flight hazard by generating vortices of the greatest strength?

A

Heavy, slow and flaps up

15
Q

What effect would a light crosswind have on the wingtip?

A

The upwind vortex will tend to remain on the runway longer than the downwind vortex

16
Q

If you take off behind a heavy jet that has just landed, where should you plan to take off?

A

Beyond the point where the jet touched down

17
Q

Washout refers to a design feature whereby?

A

The riggers angle at the wing root is greater than at the wingtip

18
Q

What is the load factor in straight and level?

A

1

19
Q

What is an indicator of a spin?

A

IAS low and almost unchanging

20
Q

What factors affect stall speed?

A

Centre of gravity
Power setting
Load factor

21
Q

Maximum range is achieved by flying at what speed?

A

The speed for minimum drag

22
Q

Maximum endurance is achieved by flying at what speed?

A

The speed for minimum power

23
Q

What is relative airflow?

A

Opposite to the direction of the path of the aircraft

24
Q

What is the angle of attack?

A

Angle between the chord line and relative airflow

25
Q

What is camber and what does increasing it do?

A

Curvature of the aerofoil
Increasing camber on upper surface will cause airflow to accelerate over it more, generating more lift at same angle of attack

26
Q

When does the maximum camber occur?

A

The point where distance between camber line and chord line is greatest

27
Q

What is couple moments?

A

Interaction of two moments separated by a horizontal distance

28
Q

Which is stronger, lift to weight couple or thrust drag couple and what force balances them out?

A

LW is stronger and the horizontal stabiliser force balances them out

29
Q

When the total pressure remain unchanged, what happens to local static and dynamic increases?

A

Static decreases

30
Q

What is likely to occur while banking in climb?

A

Over banking due to higher speed and increased angle of attack on outer wing. Outter wing crest more lift than inner

31
Q

What is likely to occur while banking in a descent?

A

Under banking in descent

Outter wing travels a greater distance while inner wing has greater AoA

32
Q

What causes aircraft to yaw out of turn?

A

Increased drag on down going aileron

33
Q

How do you minimise the affect of adverse aileron yaw?

A

Frise type ailerons
Differential ailerons
Coupling the rudder

34
Q

How do fries type ailerons work?

A

Uses offset hinges to deflect part of the up going aileron into the air, increasing drag

35
Q

How do differential ailerons work?

A

The up going aileron travels further up than the down going aileron, increasing drag

36
Q

How does coupling ailerons and rudder work?

A

As ailerons are deflected, rudder automatically moves to counter act the adverse yaw

37
Q

What is the load factor in a 60degrees AoB?

A

2g

38
Q

What is the load factor formula?

A

Lift / weight

39
Q

Which wing stalls first in a spin?

A

Down going wing

40
Q

Why is the use of ailerons close to or in a stall incorrect?

A

Down going aileron increases angle of attack further, stalling the wing further

41
Q

What is IAS likely to suffer from?

A

Pressure and instrument error

42
Q

How is calibrated airspeed calculated?

A

Corrected IAS for pressure and instrument error

43
Q

How is equivalent airspeed calculated?

A

Calibrated airspeed corrected for compressibility error. (CAS always higher than EAS)

44
Q

How is true airspeed calculated?

A

Equivalent airspeed correct for density error

45
Q

In order to fly a turn of same radius at higher airspeed, what do you need to do?

A

Fly a greater bank angle

46
Q

What is the constant rate turn?

A

180 degrees in 1min
360 degrees in 2 min
Turn of 3 degrees per second
10% airspeed + 7 = AoB (degrees)

47
Q

What two variables control turn performance?

A

Angle of bank

True airspeed

48
Q

What affect will increasing the TAS have on the radius and rate of turn?

A

Increase radius of turn

Decrease rate of turn

49
Q

What affect will decreasing IAS have on radius and rate of turn?

A

Decrease radius of turn

Increases rate of turn

50
Q

What affect will increasing the angle of bank have on radius and rate of turn?

A

Decrease radius of turn

Increase rate of turn

51
Q

What affect will decreased angle of bank have on radius and rate of turn?

A

Increase radius of turn, decrease rate of turn

52
Q

Longitudinal stability is stability about what axis?

A

Lateral axis, pitching plane

53
Q

Lateral stability is stability about which axis?

A

Longitudinal axis (rolling plane)

54
Q

Directional stability is stability about which axis?

A

Normal axis (yawing)

55
Q

Where is the restoring force for longitudinal stability?

A

Horizontal stabiliser (tail)

56
Q

How is lateral stability increased?.

A

With dihedral and high wing

Sweepback wings

57
Q

What provides restoring force for directional stability?

A

Large keel surfaces aft of CoG

58
Q

What is stronger, lateral or directional stability? What is one affect of this difference?

A

Directional stability

Spiral dive

59
Q

What is the function of the trim wheel?

A

Reduce the moment of the hinge line of the control surfaces to zero (hands off)

60
Q

Where can trim tabs be located?

A

Elevator
Rudder
Aileron

61
Q

What and why are balance tabs used for?

A

Reduce the force required to deflect control surface. Used as planes get faster and control surfaces get bigger

62
Q

What are the types of balance tabs?

A

Fixed
Aerodynamic
Automatic

63
Q

What are fixed balance tabs?

A

Small metal tab that can be bent into set position.

Only adjusted on the ground, need to be confirmed by flight test

64
Q

What are Aerodynamic balance tabs?

A

Most commonly used in rudders and elevators

Horn balance protrudes into airflow

65
Q

What are automatic balance tabs?

A

Tab is lined with control surface and automatically moves to assist control deflection.
Tab moves opposite direction to control surface to provide assisting force.

66
Q

What is mass balance?

A

Helps reduce flutter by moving CoG closer to hinge line

67
Q

When taxing into strong headwind, what should you do?

A

Control column either neutral or back

68
Q

When taxing with a strong tail, what should you do?

A

Hold control column forward