Flight Controls

Question 1

Three aircraft axis

Answer 1

• Longitudinal = roll
• Lateral = pitch
• Normal = yaw

Question 2

Elevator

Answer 2

• Located at the tailplane trailing edge
• Fore and aft movements of control column

Question 3

Ailerons

Answer 3

• Located outboard trailing edge
• Rotating of the control column

Question 4

Rudder

Answer 4

• Located trailing edge of the vertical stabiliser
• Left and right

Question 5

Fixed horizontal stabiliser with moving elevator

Answer 5

• Standard elevator
• Changes camber to create aerodynamic force

Question 6

All moving/ all flying tailplane

Answer 6

• Moves the whole horizontal stabiliser
• Changes AoA

Question 7

Rolling

Answer 7

• Control column goes left, left aileron moves up, right moves down and vice versa
• Secondary effect = yaw
• Need to use coordinated rudder and aileron to prevent skidding and slipping

Question 8

Yawing

Answer 8

• Left rudder, plane moves left
• Balance ball used to check the right amount of rudder is being used
• Secondary effect = roll
• Can lead to skidding is not counteracted by aileron
• Yaw will roll the aircraft towards the yaw

Question 9

High airspeeds

Answer 9

• More airflow
• More effective
• Better input control

Question 10

Low airspeed

Answer 10

• Less airflow
• Less effective
• Sluggish

Question 11

Effects of slipstream

Answer 11

Slipstream = stream of air propelled backward by the aircraft’s propeller.

• Increased by increasing power
• Increased effectiveness
• Aileron effectiveness will not change as it is outside of the slipstream

Question 12

Adverse yaw

Answer 12

Tendency to yaw out of turn

Question 13

Rudder input

Answer 13

• Coordinated rudder and aileron in the same direction as the roll counteracts adverse yaw

Question 14

Frise ailerons

Answer 14

The leading edge of the aileron on the down-going wing protrudes into the relative airflow as it is deflected upward, creating more drag.

The increased drag balances the drag on the up-going wing, reducing yaw.

Question 15

Differential ailerons

Answer 15

The ailerons on the down-going wing deflects upwards at a greater angle than the ailerons on the up-going wing deflect downwards.

Creates more drag on the down-going wing, balancing the drag on the up-going wing and thus reducing adverse yaw.

Question 16

Coupled controls

Answer 16

Mechanical or electronic interconnection that automatically applies some rudder in the direction of the aileron input.

Question 17

Spoiler use

Answer 17

A spoiler on the down-going wing is deployed, which increases drag and reduces lift causing the aircraft to roll.

Question 18

Purpose of trim tabs

Answer 18

Relieve the pilot of the control pressures.

Question 19

Trim controls

Answer 19

• If the pilot is holding back pressure - wind the wheel backwards and vice verse

Question 20

Aerodynamic balance

Answer 20

Designed to ensure that when the control surface is deflected, it generates a balancing aerodynamic force.

Moves the CoP closer to the hinge line.

Question 21

Mass balance

Answer 21

Involves adding weights to the control surface to prevent flutter (dangerous oscillation that can occur at high speeds).

Weights are usually placed ahead of the control surface’s hinge line to move the CoG closer to it.

Question 22

Horn balance

Answer 22

Involves extending a portion of the control surface forward of its hinge line.

This extension protrudes into the airflow on the opposite side to the main control surface’s hinge line.

It moves the CoP closer to the hinge line

Question 23

Inset hinges

Answer 23

Involve repositioning the hinge line further back.

Shortens the distance between the CoP and the hinge line

Question 24

Balance tabs

Answer 24

• Aircraft tailplane
• Move in the opposite direction to the elevator
• Mechanically linked

Question 25

Anti-balance tabs

Answer 25

- Move in the same direction as the elevators - Used to prevent it from going to full deflection

Question 26

Purpose of mass balance

Answer 26

To prevent flutter

Question 27

Flexural flutter

Answer 27

- AKA “Flexural aileron flutter” - Occurs when the aileron has a rearward CoG and the wing is disturbed up and down by turbulence - Aileron lags due to inertia - Causes structural damage

Question 28

Torsional flutter

Answer 28

- Common in flexible wings - Can lead to high speeds flutter or vibration - In turning, the wings flexibility causes the wing to twist up - Sometimes the twist can be so severe that is reverses the angle of attack, changing the direction of the aerodynamic force - Causes structural damage

Question 29

How to prevent flutter?

Answer 29

Mass/weight must be placed to reduce the lag and move the CoG closer to the hinge line

Question 30

Internal mass balance

Answer 30

Found inside the wing or control surface

Question 31

External mass balance

Answer 31

This type has mass outside the wing

Question 32

Horn balance

Answer 32

Weight can be found inside the horn which protrudes into the airflow acting as a horn balance as well.