Aerodynamic Terms Flashcards

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1
Q

Chord line

A

An imaginary straight line from the leading to the trailing edge of an airfoil. Lowering flaps changes the chord line

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2
Q

Relative wind

A

The wind felt by an airfoil. It is parallel to and travels the opposite direction of the flight path of the airfoil.

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3
Q

Angle of attack

A

Angle between the chord line and the relative wind

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4
Q

Angle of incidence

A

Angle that the wing is attached to the fuselage

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5
Q

Does the angle of attack that an airfoil stalls at change?

A

The indicated airspeed at which stalls occur is determined by weight and load factor, but the stall angle of attack is the same

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6
Q

Lateral axis

A

Imaginary line from wingtip to wingtip

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7
Q

Pitch

A

Rotation around the lateral axis. Controlled by the elevators.

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8
Q

Longitudinal Axis

A

Imaginary line from the nose to the tail

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9
Q

Roll

A

Rotation around the longitudinal axis. Controlled by the ailerons

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10
Q

Vertical axis

A

Imaginary line extending through the intersection of the lateral and longitudinal axes.

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11
Q

Yaw

A

Rotation about the vertical axis. Controlled by the rudder.

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12
Q

Center of gravity

A

Imaginary point where all the weight is concentrated and plane would balance if it were suspended. The 3 axes intersect here.

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13
Q

What are the 4 aerodynamic forces

A

Weight, lift, drag, and thrust

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14
Q

Bernoulli’s principle

A

As the velocity of a fluid increases, it’s pressure decreases

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15
Q

Lift

A

The result of a pressure difference between the top and bottom of the wing. Factors include: angle of attack, wing area and shape, air velocity, and air density.

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16
Q

Thrust

A

The forward force produced by the propeller

17
Q

Drag

A

Rearward force which resists the forward movement of an airplane through the air. There is parasite drag and induced drag

18
Q

Parasite drag

A

Resistance by any part of the plane that doesn’t produce lift, like the antennae and landing gear

19
Q

Induced drag

A

As lift is developed, the high pressure air beneath the wing causes vortices all along the trailing edge of the wings. Increases as airspeed decreases

20
Q

Unaccelerated (straight and level) flight

A

The four aerodynamic forces are in equilibrium. Lift=weight, Thrust=drag

21
Q

What determines the longitudinal stability of an airplane

A

The location of the CG with respect tot he CL(center of lift).

22
Q

3 effects of forward CG

A

1-increased longitudinal stability
2-lower cruise speed. Higher AoA to create more lift, more induced drag
3-higher stall speed.

23
Q

4 effects of aft CG

A

1- decreased longitudinal stability
2- higher cruise speed
3- lower stall speed
4- poor stall/spin recovery

24
Q

Why does a plane lose altitude on a turn?

A

A portion of the vertical lift is diverted to a horizontal lift component. So, this will happen unless you increase the AoA or airspeed.

25
Q

What can increase the load factor on the airplane?

A

Overloading the plane, too steep an angle of bank, turbulence and abrupt movement of the controls.

26
Q

What is a stall?

A

At an AoA of approximately 18-20, turbulence over the upper wing decreases lift so drastically that flight can’t be maintained.

27
Q

Critical Angle of Attack

A

The angle at which a stall occurs. An airplane can stall at any airspeed or any attitude, but will always stall at the same critical AoA.

28
Q

When will an aircraft spin?

A

Only after a stall, and for as long as the outside wing continues to provide more lift than the inside wing.

29
Q

What wing is stalled in a spin

A

Both wings are stalled, but one is stalled more than the other.

30
Q

What does extending flaps on landing do?

A

Increases lift and drag, allowing a steeper approach without an increase in airspeed.

31
Q

What is ground effect

A

Occurs when flying one wingspan or less above the surface, and the airflow is modified and can cause an airplane to become airborne before takeoff speed or float on approach.

32
Q

When are maximum vortexes created?

A

When an aircraft is heavy, clean, and slow. Land beyond the previous plane and takeoff before.