11.1.1 Aeroplane Aerodynamics and flight controls

Question 1

What are the 3 motions of an aircraft around the 3 axis’?

Answer 1

• Pitch
• Roll
• Yaw

Question 2

What are the primary flight controls?

Answer 2

• Ailerons
• Elevators
• Rudder

Question 3

On larger aircraft, what can be added to the wing to increase efficiency?

Answer 3

Roll spoilers

Question 4

What are the secondary flight controls?

Answer 4

• Slats
• Flaps
• Trim systems
• Flight spoilers

Question 5

What ailerons are used in high-speed flight?

Answer 5

Inboard ailerons

Question 6

What will happen to the aircrafts nose if an elevator deflects upwards?

Answer 6

The nose attitude would go upwards

Question 7

What is a “stabilator”?

Answer 7

A fully-movable aircraft horizontal stabiliser

Question 8

What type of aircraft are most common to have stabilators?

Answer 8

High-speed military combat aircraft

Question 9

What are the two types of canards?

Answer 9

• lifting canard

- control-canard

Question 10

What is a lifting canard?

Answer 10

The weight of an aircraft is shared between the wing and the canard

Question 11

What is a control canard?

Answer 11

Almost all of the weight is carried by the wings, the canard is primarily used for pitch control during manoeuvres

Question 12

What is the disadvantage of using lifting canards?

Answer 12

The wings need to be larger or the same size as designed without the canard (due to the requirements stating that the canard would have to stall before the main wings)

Question 13

What is the purpose of a rudder limiter system?

Answer 13

It limits rudder travel at high speeds in order to prevent rudder/stabiliser overload

Question 14

At slow speeds (<150kts), what angle will the rudder have full deflection?

Answer 14

30° is permitted

Question 15

At what speed is the intermediate (15°) travel of the rudder permitted?

Answer 15

Between 150-200 knots

Question 16

What angle is the minimum travel of the rudder at high-speeds (> 200Kts)?

Answer 16

5.7° deflection

Question 17

What is a ruddervator?

Answer 17

A combination of a rudder and elevator (v-tail)

Question 18

What are the disadvantages of a ruddervator?

Answer 18

• larger control surfaces
• no full elevator/rudder deflection at the same time
• aircraft stability is reduced
• more complicated adjustment mechanics

Question 19

What is a delta wing aircraft?

Answer 19

A tailless Aircraft like Concorde

- the aircraft has elevons (a combination of elevator and ailerons)

Question 20

What are flaperons?

Answer 20

Some aircraft have them
- they usually work as ailerons but deflect symmetrically downwards when the flaps are extended (known as the aileron droop function)

Question 21

What are wing flaps usually used for?

Answer 21

Landing - by increasing drag and lift

Take off - on Large Aircraft to increase lift

Question 22

How do the flaps work on a wing?

Answer 22

When the flaps extend they change the camber of the wing and this increases the coefficient of lift at slower speeds

Question 23

What are the types of flaps?

Answer 23

• plain
• slotted
• split
• fowler

Question 24

What type of flap is the most effective?

Answer 24

The fowler flap - up to 95% increase in the maximum lift coefficient

Question 25

What is the purpose of slots in secondary lift devices?

Answer 25

They prevent an early flow-separation

Question 26

How much do slats increase the lift by?

Answer 26

Approximately 35%

Question 27

What is the purpose of spoilers?

Answer 27

They increase drag and reduce lift

Question 28

What are Air brakes?

Answer 28

Aircraft structure that deploys outwards into the airflow. They are only located where the aircraft structure can withstand heavy air-loads

Question 29

What is spanwise flow?

Answer 29

When air particles flowing over a swept wing travel in two different angles; down the leading edge and then at right angles over the wing - thickens the boundary layer at the wing tip increasing the possibility of flow separation (at low speeds/high AOA)

Question 30

What can be used to prevent/reduce the effects of spanwise flow?

Answer 30

- Wing fences | - Saw-tooth leading edge

Question 31

What is a vortex generator?

Answer 31

It improves boundary layer control on a wing by taking relatively high energy air from outside the boundary layer and mixing it with low energy air in the boundary layer

Question 32

How are the number and location of vortex generators determined?

Answer 32

It depends on flight test investigations

Question 33

What is the purpose of a stall wedge (strip)?

Answer 33

Installed at the wing roots so that with high angles of attack it disrupts the airflow to separate early causing it to stall at the root before the wing-tips (giving ailerons maximum control throughout the stall)

Question 34

What is the purpose of a trim system?

Answer 34

It compensates for the imbalance of an aircraft

Question 35

What are the 3 control inputs for the primary flight controls in the cockpit?

Answer 35

- control column - control wheel (yoke) - rudder pedals

Question 36

What is a ruddervator made up of?

Answer 36

A mixer unit that when moving the control column, it rotates the gimbal of the mixer unit

Question 37

Airbus use side-sticks instead of a control yoke or column. How is the rudder input completed?

Answer 37

Via the rudder pedals still

Question 38

What are control runs that transmit the pilots input into the flying control system called?

Answer 38

Transmissions

Question 39

What are the main components of a mechanical control run?

Answer 39

- rods | - cables

Question 40

On larger aircraft, the pilots require assistance to operate the control surfaces. What provides this assistance?

Answer 40

The aerodynamic balance - reduces the force required to operate

Question 41

What is the purpose of a horn on an aircraft control surface?

Answer 41

It moves into the wind during deflection for aiding movement

Question 42

What are the two types of aerodynamic horn balance?

Answer 42

- horn balance | - insert hinge

Question 43

What is the disadvantage of using a balance tab?

Answer 43

It reduces the efficiency of the control surface

Question 44

How does a balance panel create differential pressure?

Answer 44

The chambers allow pressure from outside to enter via the slots which in turn produces a force in the panel to assist in the deflection

Question 45

What is the advantage and disadvantage of using an anti-balance tab?

Answer 45

Advantage: - it increases the efficiency of the control surface unlike the balance tab Disadvantage: - more effort is needed than the balance tab

Question 46

What is the purpose of a trim tab?

Answer 46

It compensates for the imbalance of the aircraft