Airplane Flight Controls

Question 1

What is the chord line?

Answer 1

• imaginary line that goes from the leading edge to the trailing edge

Question 2

What is camber?

Answer 2

• curvature of the airfoil

Question 3

What the primary flight controls?

Answer 3

• required to safely control an airplane during flight
• ailerons
• elevators
• rudder

Question 4

What are ailerons?

Answer 4

• control roll about the longitudinal axis

- operated by cables and pulleys controlled by yoke

Question 5

How do ailerons operate?

Answer 5

• attached to outboard trailing edge of each wing and move opposite of eachother
• ex. in right turn = right goes up left goes down

Question 6

How to ailerons turn the airplane?

Answer 6

• upward deflected aileron decreased camber of wing resulting in decreased lift causing wing to lower
• downward deflected aileron increased camber of wing resulting in increased lift causing wing to raise

Question 7

What is adverse yaw?

Answer 7

• downward deflected aileron produced more lift so it also produces more induced drag
• added drag causes nose to yaw in direction of raised wing
• countered by rudder

Question 8

What are the 4 different types of ailerons?

Answer 8

• differential
• frise-type
• coupled ailerons and rudder
• flaperons

Question 9

Differential Ailerons

Answer 9

• upward moving aileron raises higher than downward moving aileron
• produces increased drag on lowered wing to reduce adverse yaw

Question 10

Frise-Type Ailerons

Answer 10

• raised aileron pivots on offset hinge, projecting leading edge into airflow creating drag and reducing adverse yaw
• forms slot for air to smoothly pass through making it more effective at higher AOA

Question 11

Coupled Ailerons and Rudder

Answer 11

• ailerons and rudder are inter connected moving rudder and ailerons at same time via springs

Question 12

Flaperons

Answer 12

• combination of flaps and ailerons

- control bank but can be lowered to function as normal flaps

Question 13

What does the elevator control?

Answer 13

• controls pitch about the lateral axis

Question 14

How does the elevator work?

Answer 14

• pulling yoke backwards deflects trailing edge up decreasing camber creating downward aerodynamic force
• tail moves down as nose moves up about the CG

Question 15

What are the different types of elevators?

Answer 15

• t tail

- stabilator

Question 16

T-Tail

Answer 16

• elevator is above most downwash created from propeller

- popular because it removes tail from exhaust blast from engine

Question 17

How does slow flight affect a T-Tail?

Answer 17

• must be moved greater distance to raise nose due to lack of downwash acting on tail
• requires more control force during takeoff, landing, and stalls

Question 18

Stabilator

Answer 18

• one piece horizontal stabilizer that pivots from central hinge point
• when yoke pulled back, trailing edge raises causing nose to point up

Question 19

What are anti servo tabs?

Answer 19

• decrease sensitivity of stabilator
• moves in same direction of stabilator
• help prevent pilot from over controlling pitch

Question 20

What does the rudder control?

Answer 20

• yaw about vertical axis

- used for coordination

Question 21

How does the rudder work?

Answer 21

• when rudder is deflected into airflow creates horizontal force in opposite direction
• sideward lift due to increased camber

Question 22

What are the secondary flight controls?

Answer 22

• improve performance characteristics or relieve control pressures
• flaps
• trim tabs

Question 23

What are flaps?

Answer 23

• attached to inboard trailing edge of wing
• extended simultaneously
• increased induced drag and lift for any AOA

Question 24

Why are flaps important?

Answer 24

• increased lift allows for takeoff at lower airspeed and improves climb performance
• produces more drag allowing for steeper descent angle at slow airspeeds
• decreases amount of runway required for takeoff and landing

Question 25

What are the 4 types of flaps?

Answer 25

• plain
• split
• slotted
• fowler

Question 26

Plain flaps

Answer 26

• simplest
• increase camber = increase lift
• significantly increased drag
• creates large wake behind wing

Question 27

Split Flaps

Answer 27

• deflect from lower surface of wing
• increased drag due to turbulent airflow behind wing
• when fully extended produces high drag with little added lift

Question 28

Slotted Flaps

Answer 28

• significantly increased lift compared to plain/split
• most popular today
• when lowered forms slot for air to pass through
• high pressure air from below combines with low pressure air above delaying airflow separation producing more lift

Question 29

Fowler Flaps

Answer 29

• type of slotted flap which changes camber/increases wing area
• slides backwards on tracks
• first section creates a lot of lift but little drag
• section section creates a lot of drag but little lift

Question 30

How are flaps controlled by the pilot?

Answer 30

• mechanically, electrically, or hydraulically powered