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M11 > 11.1 THEORY OF FLIGHT👌🏼 > Flashcards

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
Q

What do drag inducing devices do?

A
  • dump lift and increase drag
26
Q

What are spoilers?

A
  • hinged panel that interrupt airflow over the wing
  • spoils lift
  • e.g. of secondary flight controls
  • increase drag
27
Q

Spoilers can serve 3 distinct primary functions, what are they?

A
  • flight spoilers (speed brakes)
  • ground spoilers (lift dumpers)
  • roll spoilers
28
Q

Explain flight spoilers?

A
  • referred to as speed brakes
  • has a max deflection angle while airborne
29
Q

Explain ground spoilers?

A
  • all spoilers are equipped with ground spoilers function
  • helps slow aircraft down by producing aerodynamic drag
30
Q

Explain roll spoilers?

A
  • 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
Q

What are wing fences?

A
  • 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
Q

What are vortex generators?

A
  • 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
Q

What are stall edges?

A
  • known as ‘stall strip’
  • encourages root to stall first
  • bonded onto wings leading edge, usually at the wing root
34
Q

What is aircraft trimming ?

A
  • adjusts aerodynamic forces to maintain set attitude
35
Q

Where are trim tabs located?

A
  • trailing edge
36
Q

How does a trim tab work?

A
  • It is deflected in the direction that opposes flight control deflection
37
Q

Explain balance tab?

A
  • when control surface is deflected, the tab automatically moves in the opposite direction
38
Q

Explain anti-balance tab?

A
  • tab moves in the same direction as the control surface
  • more effort required to deflect the control surface
39
Q

What are Servo tabs?

A
  • assists larger control surfaces to move
  • servo tabs move opposite direction to the flight control
  • pilot operated
40
Q

What are spring tabs?

A
  • like a servo tab, only works when the force on a flight control reaches a certain value
41
Q

Subsonic compressible flow speeds?

A

Mach number < 0.8

42
Q

Transonic compressible flow speeds?

A
  • Mach number 0.8 - 1.2
43
Q

Supersonic compressible flow speed?

A
  • Mach number 1.2 - 5.0
44
Q

Subsonic is greater or below the speed of sound?

What aircraft fly here?

A
  • below
  • commercial flights
45
Q

Explain transonic flight?

A
  • combination of subsonic and supersonic airflow
  • ‘normal shock-wave’ is formed (90 degrees)
46
Q

Explain supersonic flight?

A
  • > speed of sound
  • ## entire aircraft subject to supersonic airflow
47
Q

Mach 1 = ?

A
  • speed of sound
48
Q

Air is compressible at what speeds?

A
  • approx Mach 0.4
49
Q

Explain a normal shock wave?

A
  • air barrier perpendicular to airflow (90*)
  • happens in transonic flight range
50
Q

Explain Oblique shock waves?

A
  • 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
Q

What is an expansion wave?

A
  • supersonic airflow changes direction around curve/corner
  • not a shockwave
  • pressure, density and temp of air decrease
  • velocity increases
52
Q

Explain expansion wave?

A
  • not shock waves
  • supersonic airflow changes direction around curve or corner
  • pressure, density and temp of air decreases
  • velocity increases
53
Q

What are the 2 ways to reduce wave drag

A
  • vortex generators
  • area rule
54
Q

What is wave drag?

A
  • total drag created from shock waves
55
Q

Explain vortex generators?

A
  • 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
Q

Explain the Area rule related to overcoming wave drag?

A
  • reduce aircraft’s drag at transonic speeds
  • Sears- Haack body is the shape with lowest theoretical wave drag in supersonic flow
57
Q

Why is the fuselage waisted in aircraft?

A
  • ensures the volume distribution is maintained as the ‘Sears-Haack profile’
58
Q

What is aerodynamic heating also known as?

A

-friction heating
- friction of air heating airframe

59
Q

How does sweepback increases the critical Mach number?

A
  • longer chord
  • reduced thickness
60
Q

What flight control can be used as you are rolling to prevent side slip?

A
  • rudder

M11 (17 decks)

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