11.1 THEORY OF FLIGHT👌🏼 Flashcards

1
Q

Aircraft rotates about 3 primary axes ?

A
  • Lateral axis (pitch) (elevators etc)
  • Longitudinal axis (roll) (Ailerons and spoilers)
  • Vertical axis (yaw) (rudder)
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2
Q

Aircraft primary controls are ?

A
  • ailerons
  • elevators
  • rudder
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3
Q

What are stabilators?

A
  • dual purpose of horizontal stabiliser and elevators
  • commonly found on high speed military combat aircraft
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4
Q

What are variable incidence stabilisers / THS ?

A
  • limited ROM, used only for pitch trimming
  • reduce drag
  • long term adjustments
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5
Q

What are canards?

A
  • where the horizontal stabiliser is positioned at the front of aircraft (ahead of main wings)
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6
Q

If a rudder is deflected left, where does the nose point?

A
  • left
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7
Q

What are rudder limiters?

A
  • restricts rudder deflection with increasing airspeed
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8
Q

What happens if you excessively use rudder during high speeds?

A
  • lead to structural failure
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9
Q

What are elevons?

A
  • combination of elevators and ailerons
  • found on delta wing aircraft
  • no horizontal stabiliser
  • control surfaces for pitch and roll are located at trailing edge of the wing
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10
Q

What are Ruddervators?

A
  • combination of a rudder and a elevator
  • e.g. found on v tailed aircraft (do not have vertical or horizontal stabiliser)
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11
Q

Explain slots?

A
  • located on leading edge
  • allows high pressure air beneath wing to accelerate to the top of the wing and re-energises the boundary layer
  • prevents separation, stagnation, and stall at higher AOA
  • allows aircraft to fly at lower speeds at high AOA
  • frequently situated in front of ailerons so inboard part of wing stalls first and aileron functions are maintained
  • they produce a lot of drag
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12
Q

Explain slats?

A
  • located on leading edge and same function as slot but adjustable
  • increase camber, increase lift
  • allows high pressure air to accelerate over wing to re-energise boundary layer
  • can be selected as part of a configuration or manually
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13
Q

Explain flaps?

A
  • Secondary flight controls are used to increase lift during slow speeds (take off and landing)
  • produce significant drag (useful when landing)
  • nose pitch down when flaps are out
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14
Q

What is a plain flap?

A
  • 50% - 55% lift increase
  • Cause a lot of drag
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15
Q

What is a split flap?

A
  • 60% - 65% lift increase
  • causes more drag than a plain flap
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16
Q

What is a slotted flap?

A
  • slots near trailing edge when extended
  • not as much drag as plain and split
  • increases lift by 65% - 70%
  • large aircraft often have double or even triple slotted flaps
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17
Q

What is a fowler flap?

A
  • increases chord of wing then camber
  • nose down pitch movement
  • Increases lift the most (up to 95%)
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18
Q

Which flap has lift up to 95%

A
  • Fowler flap
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19
Q

What is a slotted fowler flap?

A
  • increase area of wing then camber
  • increasing lift and giving lowest drag possible
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20
Q

What do heavy aircraft have in addition to trailing edge flaps?

A
  • leading edge flaps
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21
Q

When leading edge flaps is retracted, where is it stored?

A
  • leading edge of wing
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22
Q

Explain leading edge droop?

A
  • device that improves airflow over the wings at high AOA
  • entire leading edge rotates downstairs
  • increases camber and lift
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23
Q

Explain Krueger flaps?

A
  • lift enhancement devices on leading edge
  • when deployed, produces nose up pitch
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24
Q

What are flaperons?

A
  • dual purpose (ailerons that can function as a flap)
  • during take off and landing they behave like flaps (it can still be used as a aileron)
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25
What do drag inducing devices do?
- dump lift and increase drag
26
What are spoilers?
- hinged panel that interrupt airflow over the wing - spoils lift - e.g. of secondary flight controls - increase drag
27
Spoilers can serve 3 distinct primary functions, what are they?
- flight spoilers (speed brakes) - ground spoilers (lift dumpers) - roll spoilers
28
Explain flight spoilers?
- referred to as speed brakes - has a max deflection angle while airborne
29
Explain ground spoilers?
- all spoilers are equipped with ground spoilers function - helps slow aircraft down by producing aerodynamic drag
30
Explain roll spoilers?
- used with ailerons to enhance roll control - referred as ‘spoilerons’ - can be deployed on 1 wing to better the roll - spoilers allow aircraft to roll without creating a twisting force
31
What are wing fences?
- reduce span wise flow and helps reduce the wing tip stalling on swept back aircraft - usually installed on leading edge - known as ‘boundary layer fences’
32
What are vortex generators?
- device used to re-energise boundary layer - produces lift that acts sideways - high pressure spills over the tip to enter low pressure side and causes a vortex
33
What are stall edges?
- known as ‘stall strip’ - encourages root to stall first - bonded onto wings leading edge, usually at the wing root
34
What is aircraft trimming ?
- adjusts aerodynamic forces to maintain set attitude
35
Where are trim tabs located?
- trailing edge
36
How does a trim tab work?
- It is deflected in the direction that opposes flight control deflection
37
Explain balance tab?
- when control surface is deflected, the tab automatically moves in the opposite direction
38
Explain anti-balance tab?
- tab moves in the same direction as the control surface - more effort required to deflect the control surface
39
What are Servo tabs?
- assists larger control surfaces to move - servo tabs move opposite direction to the flight control - pilot operated
40
What are spring tabs?
- like a servo tab, only works when the force on a flight control reaches a certain value
41
Subsonic compressible flow speeds?
Mach number < 0.8
42
Transonic compressible flow speeds?
- Mach number 0.8 - 1.2
43
Supersonic compressible flow speed?
- Mach number 1.2 - 5.0
44
Subsonic is greater or below the speed of sound? What aircraft fly here?
- below - commercial flights
45
Explain transonic flight?
- combination of subsonic and supersonic airflow - ‘normal shock-wave’ is formed (90 degrees)
46
Explain supersonic flight?
- > speed of sound - entire aircraft subject to supersonic airflow -
47
Mach 1 = ?
- speed of sound
48
Air is compressible at what speeds?
- approx Mach 0.4
49
Explain a normal shock wave?
- air barrier perpendicular to airflow (90*) - happens in transonic flight range
50
Explain Oblique shock waves?
- airflow formed at another angle - faster than speed of sound (> Mach 1) - as it passes through the wave, velocity of airflow is reduced but remains supersonic - slight increase in temp and pressure
51
What is an expansion wave?
- supersonic airflow changes direction around curve/corner - not a shockwave - pressure, density and temp of air decrease - velocity increases
52
Explain expansion wave?
- not shock waves - supersonic airflow changes direction around curve or corner - pressure, density and temp of air decreases - velocity increases
53
What are the 2 ways to reduce wave drag
- vortex generators - area rule
54
What is wave drag?
- total drag created from shock waves
55
Explain vortex generators?
- transfers energy from the free air stream to the boundary layer (produce vortex) - reduce flow separation - produces oblique shock wave inside the supersonic airflow
56
Explain the Area rule related to overcoming wave drag?
- reduce aircraft’s drag at transonic speeds - Sears- Haack body is the shape with lowest theoretical wave drag in supersonic flow
57
Why is the fuselage waisted in aircraft?
- ensures the volume distribution is maintained as the ‘Sears-Haack profile’
58
What is aerodynamic heating also known as?
-friction heating - friction of air heating airframe
59
How does sweepback increases the critical Mach number?
- longer chord - reduced thickness
60
What flight control can be used as you are rolling to prevent side slip?
- rudder