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POF > Wing Design > Flashcards

Wing Design Flashcards

1
Q

High Aspect Ratio on lift/drag

A

High Cl
Less wing tip vortices less induced drag from lower span wise pressure gradient

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2
Q

Wing Loading

A

How much lift needed to produce weight
Measured in kg/m2

Small span heavy ac - High wing loaded
Large span light ac - Low wing loaded

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3
Q

Span Wise Distribution

A

Change in lift across the span

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4
Q

Methods for reducing Cl peak at tip

A

Camber changes (less towards tip)
Washout - reduce AOI to reduce local AOA at tip
Surface area reduction at tip

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5
Q

Ellipetical Wing

A

Constant CL
Lift drops towards span
Expensive not used on CAT

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6
Q

Rectangular Wing

A

Greatest lift at root
Cl reduces towards tip
IAOA increases/EAOA reduces/Induced drag increases
More downwash towards tip

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7
Q

Tapered Wing

A

CL peak at mid span
Ideal taper ratio of 0.5

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8
Q

Sweep back wing

A

Greatest downwash at root
EAOA greatest towards tip
Wing tip vortex thanks to downwash

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9
Q

Modern A/C design

A

Swept + Tapered
Not great stall characters tip stalling
Economical
Closest to elipetical design

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10
Q

Sweep Angle

A

Angle at which wing is inclined to the lateral axis
Usually measure at 25% of the chord

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11
Q

Taper Ratio Formula

A

Tip Chord/Root

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12
Q

Aspect Ratio Formula

A

Wingspan2/wing area

Span2/ area

Span/chord

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13
Q

Thickness/Chord Ratio

A

The ratio of max thickness of an aerofoil on the chord length expressed as a percentage

Usually between 10% to 12%

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14
Q

Mean Aerodynamic Chord is

A

The chord of an equivalent untwisted rectangular wing with the same pitching moment and lift characteristics as the actual wing

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15
Q

Spanwise flow is higher in

A

Slow speed/high aspect ratio ac

(Slow flight less KE so more inclined to flow Spanwise)

(Faster planes/shorter cord less)

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16
Q

Effective AOA is the angle between

A

The angle between the effective airflow and the chord line

17
Q

Induced AOA is the angle between

A

Between the relative airflow and the effect air flow

18
Q

Smaller wing tip vortices means

A

Greater effective AOA and smaller Induced AOA as Effective airflow is less inclined

19
Q

Strong vortices does what to downwash and EAF

A

Increases the downwash inclining the EAF upwards

20
Q

Smaller vortices means

A

Shallow effective airflow angle
Bigger effective AOA
Smaller induced AOA
Less induced drag

21
Q

Wing tip vs wing root on a rectangular ac

A

Wing tip = strong vortices/greater effective airflow/smaller eAOA/larger induced AOA

Wing root = weaker vortices/greater effective AOA

22
Q

Directional flow of trailing tip vortex

A

Span wise flow is always outward from under wing to upper surface

Anti clockwise around right wing
Clockwise around left wing

When viewed from behind

23
Q

What wing produces the lowest induced drag

A

Ellipetical wings produce the most lift for the smallest wing tip vortices

At there tips the pressure differential is almost 0

24
Q

Wing Loading

A

Measured in kg/m2
Weight per unit of the wing area

Greatest on heavy ac with smaller wings = higher wing loading

More intense vortices

25
Q

Which wing planform has the lowest induced drag

A

Ellipetical wing

26
Q

Which wing has the highest induced drag

A

Rectangular (longer tip chord)

27
Q

Swept back wing advantages and disadvantages

A

+ Increases the critical Mach number
+ Positive contribution to static directional stability
+ Positive significant contribution to static lateral stability

  • tip stall and pitch up at stall
  • lower cl for given AOA which increases stall speed
  • clmax less and occurs at higher AOA
  • change in CL per change in alpha is less
  • must have complex high lift devices to to/ld
  • must be flown at high AOA than straight wings for cl
28
Q

Wing AOA

A

Chord to the relative airflow

29
Q

Aeroplane AOA

A

Longitudinal axis to relative air flow (speed vector)

30
Q

Angle of incidence

A

Wing root chord to longitudinal axis

POF (25 decks)

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