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Willys Flashing > 11.1 > Flashcards

11.1 Flashcards

1
Q

What are the three axis of aircraft and their directions?

A

-Lateral = wing tip to tip
-Longitudinal = nose to tail
-Vertical = through centre

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2
Q

Which axis relates to each type of movement?

A

Lateral = Pitch
Longitudinal = Roll
Vertical = Yaw

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3
Q

What control do ailerons provide?

A

Longitudinal axis (Roll)

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4
Q

What are ailerons controlled by?

A

Yoke or side to side stick

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5
Q

How does the ailerons function in terms of creating roll movement?

A

An upward deflection on the wing that rolls downwards which reduces the Camberwell and therefore lift and a downward deflection on the opposing wing have the opposite effect

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6
Q

At high speed how can an exceeding of max load capacity be negated?

A

The outboard ailerons are locked and inboard are used only in some aircraft in addition to roll spoilers

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7
Q

What is one use of spoilers?

A

Supplemental aileron control

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8
Q

What control are elevators used for?

A

Pitch control

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9
Q

What control are stabilators used for?

A

Combined elevator and horizontal stabiliser action

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10
Q

What is the function of variable incidence stabiliser?

A

AKA (trimmable horizontal stabiliser)
For pitch trimming only, with less drag

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11
Q

What moves variable incidence stabilisers?

A

A screw jack mechanism

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12
Q

What is the primary function of canards?

A

Pitch control

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13
Q

What can canards effect?

A

-Stability
-Stall prevention
-High angle of attack manoeuvres
-Lift and trim

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14
Q

What is the function of the rudder?

A

Directional or yaw control

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15
Q

How is the rudder controlled?

A

With pedals

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16
Q

What is the purpose of rudder limiters?

A

To prevent structural damage at high speed

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17
Q

What is effected by rudder limiters?

A

The movement of the rudder not the pedal movement

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18
Q

What is the relationship between yaw and roll?

A

When yaw occurs one wing advances creating lift and causing roll

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19
Q

What is adverse yaw?

A

Induced drag cause the aircraft to yaw in the opposing direction to that of the roll

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20
Q

What can be used to limit adverse yaw

A

Frise ailerons

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21
Q

Which wing profile is particularly prone to instability in yaw and roll?

A

Swept

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22
Q

What is an elevon?

A

A combined surface on delta for pitch and roll control

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23
Q

What is a ruddervator?

A

V tail aircraft rudder and elevator combined

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24
Q

What are slots? Where are they used? Why and how?

A

-fixed convergent gaps
-primarily on outboards leading edge
-the allow high energy air to come up and re energise the boundary layer

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25
Q

What do slots allow for?

A

-Slower speeds
-higher angles of attack

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26
Q

What is the largest disadvantage of slots?

A

High Drag

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27
Q

How do slats work?

A

Basically a retractable slot, additionally increasing camber when not in use

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28
Q

What are flaps?

A

Secured to the trailing edge they increase lift by extending length and camber, they can tend to pitch nose down

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29
Q

What is the function of plain flaps and their design

A
  • 50-55% increase in lift
  • pitch nose down
  • high drag
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30
Q

What is the design and function of split flaps?

A
  • Stores flush and disconnects from main surface
  • Increases camber and lift by 60-65%
  • higher drag than plain flaps
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31
Q

How does a slotted flap function and how is it designed?

A
  • The slots in the flaps re energise the boundary layer
  • camber increases but not surface are so there is no large increase in drag
  • lift goes up by 65-70%
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32
Q

How does the fowler flap function?

A
  • 95% increase in lift
  • increases chord and camber
  • pitches nose down
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33
Q

Slotted fowler flap advantages?

A
  • lowest drag penalty
  • fowler and slot design
34
Q

When and how are leading edge flaps used?

A

Only in conjunction with conventional flaps on larger aircraft

35
Q

What are leading edge droops and how do they function?

A
  • Improves lift in higher angle of attack by improving airflow
  • rotates on the leading edge
36
Q

What are Krueger flaps and how do they function?

A

A portion of the lower wing is mechanically rotated on top which increases camber

37
Q

What are flaperons?

A

Ailerons that can function as flaps

38
Q

What is the primary function of spoilers?

A

A hinged panel which creates drag

39
Q

In terms of flight what can spoilers do?

A

Act is in flight speed brakes by being deployed at a limited lower angle

40
Q

When ground spoilers are deployed how do they function?

A

They extend to the max level, produce drag often deploy automatically when armed to do so

41
Q

How do roll spoilers function?

A
  • Enhance roll control
  • oppose adverse yaw
  • outboard or mid span
  • applied at higher speed
42
Q

What are speed brakes and how do they function?

A
  • fuselage mounted panels
  • slow the aircraft
  • control speed
43
Q

What is the function of wing fences?

A

Reduces wing spall tendency in swept wings by reducing span wise flow

44
Q

What is the function of a saw tooth leading edge?

A

Reduces wing tip stall and limits boundary layer outflow through vortex creation

45
Q

What is the function of vortex generators?

A
  • re-energise slow moving boundary layer by taking high energy air from outside boundary layer
  • small airfoil section placed on larger wings
46
Q

Function of stall wedges?

A

A ridge on the wing near the root to encourage root first stalls by encouraging flow separation

47
Q

What are trim tabs?

A

They compensate for imbalance and allow for easier adjustment of control surfaces

48
Q

Which direction is a trim tab deflected?

A

The opposing direction of the flight control surface

49
Q

How does a balance tab function?

A

When a control surface is moved it moves automatically and reduces the force required however it reduces the effectivity of of the control surface

50
Q

How does an anti balance tab function?

A

The tab moves in the same direction of the control surface to give resistance and give a feel for more accurate adjustments

51
Q

What are servo tabs?

A

On larger aircraft used as an operating method for the primary flight control surface

52
Q

How do spring tabs function?

A

Similar to a servo but only allow the surface to move once a specific value is overcome

53
Q

Why is mass balancing done?

A

To limit fluttering

54
Q

What is horn balance?

A

A designed shape or movement of the hinge which balances the aerodynamic force

55
Q

How do balance panels function?

A

And upper and lower chamber sealed but allow outside pressure to enter through slots to aid in the control surface movement

56
Q

What is the Mach number equation?

A

Velocity of object (V) / speed of sound (A)

57
Q

Flow speeds of subsonic, transonic and supersonic?

A
  • subsonic = Mach number below 0.8
  • transonic = Mach number between 0.8 - 1.2
  • supersonic = Mach number from 1.2 - 5
58
Q

What is presumed in subsonic flight?

A

Air is incompressible

59
Q

What is true of speed in transonic flight?

A

A normal shockwave forms at 90 degrees halfway over the wing, there is a combination of subsonic and supersonic flight and the centre of lift shifts backwards

60
Q

What are the features of lift and characteristics of supersonic flight?

A
  • The shockwaves are left behind and fixed to the trailing edge
  • There is almost no pressure change and a slight density change
  • low coefficient of lift and high coefficient of drag
  • drag is higher but not as high as transonic
  • lower lift
61
Q

What is the critical Mach number?

A

The lowest speed that some airflow will be over the speed of sound

62
Q

What is the compressibility buffet?

A

Around Mach 0.4 air becomes compressible creating a pressure wave drastically increasing drag

63
Q

What is a shock wave?

A

An air barrier

64
Q

What is a normal shockwave?

A

Forms at a right angle to the airflow path

65
Q

In transonic flow what the increase in drag

A

The boundary layer thickens becoming turbulent and losing energy causing flow separation

66
Q

What are oblique shockwaves?

A

The shockwave sticks to the leading edge sloping backwards

67
Q

What is an expansion wave?

A

When supersonic flow travels over a curve or corner and changes direction

68
Q

Where on a chord is the centre of lift in supersonic flow?

A

50 percent of chord position

69
Q

Where on the chord is the centre of lift for subsonic flow?

A

25 percent of chord

70
Q

What is wave drag?

A

Portion of total drag which is caused by shockwaves

71
Q

How can you limit wave drag?

A

Area rule or vortex generator

72
Q

Which design has the lowest theoretical wave drag?

A

Sears-haack body

73
Q

What can be done to limit wave drag in terms of area rule?

A

Wasting or limiting change in shape

74
Q

What temperature does aluminium alloy lose 80 percent of its strength?

A

250 degrees

75
Q

What is the maximum axial velocity a gas turbine can accept?

A

Mach 0.4

76
Q

How does a normal shock diffuser function?

A

It creates a normal shockwave, suitable for low supersonic speeds

77
Q

What occurs when supersonic flow reaches a converging duct?

A

It chokes and velocity decreases

78
Q

How does an oblique inlet work?

A

Creates one or a series of oblique shockwaves to minimise the intensity of the normal shockwave

79
Q

What is the benefit of a variable supersonic inlet?

A

It can actuate depending on Mach

80
Q

How does sweeping decrease mcrit?

A

Increases chord length

81
Q

What is a typical sweepback angle?

A

30 degrees

82
Q

What is the equation for profile thickness?

A

Actual thickness / chord length

Willys Flashing (24 decks)

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