Basic Aerodynamics Flashcards Preview

18A - Aerodynamics and Performance > Basic Aerodynamics > Flashcards

Flashcards in Basic Aerodynamics Deck (22):
1

Understand Bernoulli's Law

Total pressure equals static (P) plus dynamic pressure (q) Assuming constant density, an increase in velocity will increase dynamic pressure, causing a drop in static pressure

2

Discuss and understand basic aerodynamic forces

Label a picture of the following: Lift, Drag, CP, AC, Resultant AF, Weight, Thrust

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3

Discuss Equal Time Theory

The difference in pressure across the airfoil produces lift Air molecules flowing over the top of a wing have father to travel than along the bottom

4

Lift is the force component _________ to the oncoming flow

Perpendicular

5

Drag is the force component __________ to the oncoming flow

Parallel

6

How does an airfoil effecting flow

Air is turned both above and below the wing so upper and lower surface contribute to the flow turning and producing lift. For typical airfoils at subsonic speeds, the top surface contributes more flow turning than the bottom surface, causing pressure differential along the top to be significantly larger

7

CL is constant for each ______, but varies with ______

CL is constant for each wing shape, but varies with AoA (Angle of Attack)

8

Label a picture with Airfoil Forces; include Center of Pressure, Aerodynamic Center, Center of Gravity, Angle of Attack, Relative Wind, Chord, Lift, Drag, Weight, Resultant AF. 

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9

Define Airfoil Forces:

Chord Line

AoA

cg

cp

AF

AC

ROT

Chord Line: Straight line from leading edge to trailing edge

AoA: Angle between relative wind and the chord

cg: Point on the chord line where all effective weight is realized

cp: Point on the chord where resultant AF act (moves with AoA)

AF acts through the cp and is the vector sum of lift and drag

AC: Point around which the pitching moment occurs (also the central point of the lateral axis)

ROT: The AC is an average of the cp and cg

 

10

Discuss the difference between Aerodynamic Center vs Center of Gravity

AC moves dynamically- function of speed and AoA

cg moves statically- function of aircraft loading (fuel, stores, etc)

11

Define Static Margin

Static margin is the difference between the location of the cg and the AC

Positive: cg forward of AC

Neutral: cg at AC

Negative: cg aft of AC

12

Explain how Aircrew can modify CL

Flaps modify camber and wing area, so increases in AoA modify flow separation and lift production of a given wing or shape

For a given AoA, trailing edge flaps increase CL, but decrease stall AoA

13

Define Fowler Flaps

Fowler Flaps move aft and down producing significant modifications in Camber and Surface Area

14

Define Stall

Stall is defined as an increase in AoA with no increase in CL, or where you exceed the critical AoA

15

Define Induced Drag

Drag due to the production of lift

16

Define Thrust Available

Generates velocity to produce lift, required to overcome drag

Thrust available is relatively constant, increases slightly with velocity

17

Label Drag Curves and where "behind the power curve" is located

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18

Label AoA, Flight Path Angle, and Pitch Angle on a chart

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19

What is AoA

The angle between the oncoming air or relative wind and a reference line on the airplane or wing

20

What is pitch

Pitch angle, or attitude, is the angle between the longitudinal axis and the horizon

21

What is flight path angle

Angle between horizon and climb/descent angle

22

Define P-Factor

The horizontal blade moving down will have greater AoA producing more thrust than the horizonal blade moving up.