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AT 106 > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

List some examples of airfoils outside of aviation

A

Heart valve leaflets
Parachute
Canopies
Thin sails
Kites
Flags
Weather vanes
Bird, insect, and bat wings

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2
Q

What is an airfoil?

What can you find them on?

A

A shaped surface that produces lift and drag when moved through the air

Airplane wing, tail, propeller blade

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3
Q

Describe early airfoil designs

A

Deeply cambered
Some open on the bottom
Resemble bird wings

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4
Q

What was the early ancestor of NASA?

A

NACA (The National Advisory Committee for Aeronautics)

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5
Q

Why were early airfoil designs ditched?

A

Not optimal for aerodynamics
Less lift and more drag than modern designs

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6
Q

What are the two types of transonic airfoils?

What is special about their design?

Why are they designed like this?

A

Circular arc supersonic airfoil
Double wedge supersonic airfoil

Sharp leading and trailing edges
Maximum thickness near the middle

Reduces air velocity over upper surface and delays drag that occurs at the speed of sound

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7
Q

What is ground effect?

A

When an aircraft flies less than one-half its wingspan above the ground, area where aircraft will fly even before it is ready

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8
Q

What is a laminar boundary layer?

Is there turbulence in this layer?

A

When air is moving smoothly over the wing

No turbulence

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9
Q

What is the transition region?

What causes this region to begin?

A

When air moving over the wing begins to separate

Higher AOA

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10
Q

What is a turbulent boundary layer?

What causes this?

A

When air moving over the wing begins to separate
Causes an increase in drag

Higher AOA

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11
Q

The _____ the AOA, the _____ turbulent.

A

higher
more

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12
Q

What do wing fences do?

What types of aircraft are they often found on?

A

Obstruct span-wise airflow to prevent the entire wing from stalling at once

Swept wing aircraft

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13
Q

What are vortex generators?

What do they do?

A

Small airfoils installed in pairs

Prevent airflow separation

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14
Q

Where are vortex generators mounted?

Why?

A

Upper surface of the wing and on the empennage

Improve flight characteristics on the wing at high speed and on the empennage for low speed

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15
Q

What is planform?

A

The shape of the wing as viewed from above

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16
Q

What is taper?

What are advantages to tapering a wing?

A

The decrease in wing chord from wing root to wing tip

Decreases drag
Increases lift
Decreases the weight of the plane

17
Q

List pro(s) and con(s) for rectangular wings

A

Pros:
Cheap and easy to produce
Cheap and easy to maintain
Stable and easy to control

Con:
Large wingtip vortexes

18
Q

What stalls first on a rectangular wing?

A

Roots

19
Q

List pro(s) and con(s) for moderate taper wings

A

Pros:
More lift
Less drag
Less weight

Con:
Whole wing stalls at once

20
Q

What stalls first on a moderate taper wing?

A

Whole wing stalls at once

21
Q

List pro(s) and con(s) for high taper wings

A

Pros:
More lift
Less drag
Less weight

Con:
Stalls from wing tips first

22
Q

What stalls first on a high taper wing?

A

Wing tips

23
Q

List pro(s) and con(s) for pointed tip wings

A

Pro:
Less wingtip vortexes

Con:
Stalls from wing tips first

24
Q

What stalls first on a pointed tip wing?

A

Wing tips

25
Q

List pro(s) and con(s) for sweptback wings

A

Pros:
Efficient at high speeds
Delays shock waves

Cons:
Stalls from wing tips first
Can get Dutch roll
Unfavorable at low speeds

26
Q

What stalls first on a sweptback wing?

A

Wing tips

27
Q

List pro(s) and con(s) for elliptical wings

A

Pros:
Most efficient
Less induced drag

Cons:
Whole wing stalls at once
More complicated and expensive to build

28
Q

What stalls first on a elliptical wing?

A

Whole wing stalls at once

29
Q

What is spanwise flow?

A

Air flows perpendicular to the chord line on a sweptback wing

30
Q

What is the goal of sweptback wings?

A

Produce enough lift to keep the plane in the air so it can fly as fast as possible, without exceeding any part of the airflow reaching the speed of sound

AT 106 (13 decks)

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