Four Forces of Flight

Question 1

Lift

Answer 1

– “Upward Force created by the wings as air passes above and below them.”
* Perpendicular to the relative wind.
* Acts through one point called the “Center of Pressure”

Question 2

Center of pressure

Answer 2

Where the lift is concentrated and moves along the chord line

Question 3

Airfoil

Answer 3

Is any surface, such as a wing, that provides aerodynamic force when it interacts with a moving stream of air to generate lift

Question 4

Newtons third law of motion

Answer 4

For every action there is an equal and opposite reaction

Question 5

Bernoulli’s principle

Answer 5

The total energy in a steadily flowing fluid is constant along the path

Question 6

Types of airfoil

Answer 6

Cambered

Symmetrical

Question 7

Relative wind

Answer 7

Wind felt parallel to, and in the opposite direction of travel.

Question 8

Angle of Attack

Answer 8

Angle between chord line and the relative wind

Question 9

Lift Formula

Answer 9

CL x 1/2 pV^2 S

Question 10

Stall

Answer 10

Is an event were the wing stops generating lift.
* Happens when the critical angle of attack is exceeded

Question 11

Adverse pressure gradient

Answer 11

an adverse pressure gradient occurs when the static pressure increases in the direction of the flow (dP/dx > 0), causing the fluid velocity to decrease, potentially leading to flow separation

Question 12

Signs of stall

Answer 12

High angle of attack
Decreasing airspeed
Sluggish controls
Stall horn
Buffeting
Nose down attitude
-VSI

Question 13

Stall Recovery

Answer 13

Reduce the angle of attack by pushing the stick forward and add full power.

Question 14

Vso

Answer 14

Stall speed in landing configuration

Question 15

Vs1

Answer 15

Stall speed in clean configuration

Question 16

Weight

Answer 16

• The downward pull of gravity
• Oriented Straight to the ground
• Acts through a point called center of gravity

Question 17

Thrust

Answer 17

• Forward motion produced by the powerplant
• Focused at the thrust line

Question 18

Drag

Answer 18

– Resistance to forward motion as the aircraft travels through the air.
– Opposite the direction of flight.

Question 19

Types of drag

Answer 19

Induced drag
Parasite Drag

Question 20

Induced drag

Answer 20

Produces whenever the
airplane produces lift or it
is a byproduct of lift

Question 21

Wingtip vortices

Answer 21

swirling air masses, or “wake turbulence,” that form at the tips of aircraft wings as a byproduct of lift generation and can pose a hazard to other aircraft.

Question 22

Methods to reduce induced drag

Answer 22

Tapering the wings
Wingtip modification
Wing Washout

Question 23

Angle of incidence

Answer 23

– Angle at which the wing is aligned with the body
(longitudinal axis) of the aircraft
– Cannot be controlled by the pilot (location is decided during Airplane design process)

Question 24

Parasite Drag

Answer 24

-Any drag that is not associated with the
production of lift

-Is caused by any aircraft surface which deflects or interferes with the smooth airflow around the airplane

Question 25

Types of Parasite Drag

Answer 25

Skin Friction Drag Interference Drag Form drag

Question 26

Form Drag

Answer 26

Produced whenever the airflow passing over the aircraft separates from the surface and become turbulent.

Question 27

Skin Friction Drag

Answer 27

* Is caused by the roughness of the airplane’s surface * Creates small eddies which contribute to the drag

Question 28

Interference Drag

Answer 28

Caused by intermixing currents of air around the aircraft structure * Happens where the aircraft surfaces meet each other

Question 29

Total Drag

Answer 29

Induced Drag + Parasite Drag