AA1201 Forces and Lift

Question 1

Definition of angle of attack

Answer 1

The angle between the chordline of an airfoil and the relative wind

Question 2

Define static pressure

Answer 2

Force produced by the random movement of air molecules (static port)

Question 3

Define dynamic pressure

Answer 3

Measure of impact pressure molecules (pitot tube)

Question 4

Define total pressure and how it relates to aircraft systems

Answer 4

The sum of static and dynamic pressure. An aircraft pitot-static system measures the difference between total and static pressure

Question 5

What are the 4 aerodynamic forces?

Answer 5

Lift, weight, thrust, and drag

Question 6

What is the relationship of the 4 forces in straight and level unaccelerated flight?

Answer 6

lift = weight, thrust=drag

Question 7

What is the relationship of the 4 forces in a descent?

Answer 7

lift

Question 8

What is the relationship of the 4 forces in climb?

Answer 8

lift > weight

Question 9

What is the relationship of the 4 forces in a decceleration?

Answer 9

thrust

Question 10

What is the affect of increasing airspeed on lift?

Answer 10

If CAS increases, so does lift

Question 11

What does lowering flaps on a symmetric airfoil do?

Answer 11

Turns it into a cambered airfoil

Question 12

What are two things flaps do for a symmetric airfoil?

Answer 12

Cause an increase in coefficient of lift and slight decrease in stall AOA

Question 13

Define stall angle of attack

Answer 13

The maximum lift available at a given airspeed (L/D max)

Question 14

How is level-flight stall speed affected by a change in weight?

Answer 14

Increased weight requires increased lift which increases stall speed

Question 15

How is level-flight stall speed affected by a change in flap setting?

Answer 15

Stall speeds are lower with flaps down since flaps change the lift-producing properties of the wing

Question 16

How is stall speed affected by a change in bank angle?

Answer 16

Higher bank angles require more lift to maintain level flight (accelerated stall), therefore stall speed increases as bank increases

Question 17

Lift on a wing is caused by what?

Answer 17

Lower static pressure on top surface than bottom surface

Question 18

On a graph of coefficient of lift versus AOA, the stall AOA is the AOA where ____ is maximized

Answer 18

coefficient of lift

Question 19

Lift is the portion of net aerodynamic force which acts ___ to relative wind

Answer 19

perpindicular

Question 20

Between symmetric and cambered airfoils, which stalls at lower AOA

Answer 20

cambered

Question 21

If AOA is constant, what effect does increasing airspeed have on lift?

Answer 21

Lift increases

Question 22

For a constant airspeed, an increase in AOA has what effect on lift?

Answer 22

Lift increases