Aero 2: Stalls & Drag Flashcards

1
Q

Total Drag

A

The sum of parasite drag and induced drag

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2
Q

Parasite Drag

A

All drag not associated with the production of lift.

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3
Q

Form Drag

A

Drag resulting from the airflow separation over a surface and the low pressure wake created

Is a component of Parasite Drag

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4
Q

Friction Drag

A

Drag arising from friction forces at the surface of an aircraft, due to the viscosity of the air

Is a component of Parasite Drag

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5
Q

Induced Drag

A

That portion of total drag resulting from the production of lift

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6
Q

Boundary Layer

A

The layer of airflow over the surface of an airfoil, which shows local airflow retardation caused by viscosity

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7
Q

Stall

A

A condition of flight in which an increase in AOA will result in a decrease in the coefficient of lift

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8
Q

Spin

A

An asymmetrical aggravated stall resulting in autorotation

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9
Q

Drag

A

The component of the aerodynamic force that is parallel to relative wind and acts in the same direction

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10
Q

What factors affect induced drag?

A

Lift
Weight
Air density
Velocity
Wing span

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11
Q

How can induced drag be minimized?

A

(1) Increasing density, velocity, or wingspan

(2) Install devices to impede airflow around the wingtip (spanwise airflow) such as winglets, missile rails, and wingtip tanks

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12
Q

L/Dᴍᴀx

A

The greatest ratio of lift to drag

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13
Q

L/Dᴍᴀx AOA

A

The most efficient AOA for that airfoil

Also known as max range

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14
Q

How does velocity change total drag?

A

As airspeed decreases to stalling speed, total drag increases due to induced drag increase.

As airspeed increases to terminal airspeed/velocity, total drag increases due to parasite drag increase.

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15
Q

On the total drag curve, which type of drag dominates at lower airspeeds?

A

Induced drag

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16
Q

On the total drag curve, which type of drag dominates at higher airspeeds?

A

Parasite drag

17
Q

How can form drag be reduced?

A

By creating a more streamlined object

Form drag is easier to reduce than friction drag

18
Q

How can friction drag be reduced?

A

(1) By using a glossy, flat finish on plane surfaces

(2) By removing protruding heads, any surface roughness, and irregularities

19
Q

What types of flow are present with the boundary layer?

A

Laminar flow and turbulent flow

20
Q

Laminar flow

A

Boundary layer airflow that is smooth/ unbroken (creates little friction)

21
Q

Turbulent flow

A

Boundary layer airflow characterized by turbulent, unsteady airflow (creates more friction)

22
Q

Which boundary airflow sticks to the boundary layer? Which does not?

A

Turbulent airflow sticks to the boundary layer. Laminar airflow separates from the boundary layer easily.

23
Q

What is the difference between speeds for a power-on stall and a power-off stall?

A

Power-off stall speeds are higher because the engines are at idle

Higher stall speed means it’s easier to stall at a high speed (not good)

24
Q

What must be present for an aircraft to spin?

A

(1) Aircraft must be stalled

(2) Yaw present

25
What is the relationship between the wings during a spin?
The inside wing is more stalled than the outside wing (due to higher AOA). This causes the inside wing to have more drag than the outside wing.
26
How do you recover from a spin?
(1) Correct the stall by reducing excessive AOA (2) Correct the yaw input by applying opposite rudder PARE Procedure
27
What causes induced drag?
It is caused by air downwash that is created from wingtip vortices from spanwise airflow over the wings
28
Induced Drag Formula
Di = kL² / (ρV²b²)
29
How thick is the boundary layer?
About 1mm thick
30
Stall Equation
Vₛ= sqrt(2W/ρSCₗₘₐₓ)