11.01 Theory of Flight

Question 1

What are the three axes of motion?

Answer 1

Lateral, longitudinal and vertical

Question 2

Which flying controls control movement around the lateral axis?

Answer 2

Elevators

Question 3

What is meant by aileron lockout?

Answer 3

Outboard ailerons become inactive

Question 4

What are the advantages and disadvantages of a V tail?

Answer 4

A:
- Weight saving
D: 
- More complicated adjustment
- Needs larger surface area
- Less stable
- Cant get full elevator and full rudder simultaneously

Question 5

What are the secondary flying controls?

Answer 5

Lift devices and trim systems

Question 6

What lift device gives the maximum increase in lift?

Answer 6

Triple slotted fowler flap

Question 7

What are trim systems used for?

Answer 7

To compensate for aircraft imbalance

Question 8

How do vortex generators reduce wave drag?

Answer 8

By producing an oblique shockwave inside the suspersonic airflow

Question 9

Name the three types of balance used on flying controls

Answer 9

• Balance tab
• Anti balance tab
• Balance panel

Question 10

Does the balance tab aid the pilot?

Answer 10

Yes

Question 11

What is an anti balance tab?

Answer 11

A tab that moves in the same direction as the control surface increasing the effectiveness of the control surface

Question 12

What property of air changes with the onset of transonic flight?

Answer 12

It becomes compressible (large pressure and density changes)

Question 13

What is mach number?

Answer 13

Aircraft speed divided by speed of sound

Question 14

What is the critical mach number?

Answer 14

the fastest speed the aircraft can achieve without being subjected to supersonic airflow

Question 15

What wing design feature delays the onset of Mcrit?

Answer 15

Wing sweep

Question 16

Where does supersonic airflow first occur on an aerofoil?

Answer 16

On the upper surface

Question 17

How are oblique shockwaves employed in intakes?

Answer 17

To gradually slow the supersonic airflow before the normal shock occurs

Question 18

What happens to air velocity in an expansion wave?

Answer 18

It increases

Question 19

Why does flow separation occur behind a shockwave?

Answer 19

Boundary layer does not have enough kinetic energy to withstand the large increase in static pressure

Question 20

When does a bow wave form in front of the leading edge?

Answer 20

When flight speed exceeds the speed of sound

Question 21

What drag increases due to the use of vortex generators?

Answer 21

Parasitic drag

Question 22

Which wing profile is also known as rear loaded?

Answer 22

Transonic

Question 23

What are the possible advantages of a rear loaded wing profile?

Answer 23

• Lighter
• greater fuel capacity
• less drag
• less sweepback
• smaller wing
• better low speed characteristics

Question 24

How is tuck under avoided on modern aircraft?

Answer 24

Mach trim system

Question 25

Where on the wing does a shockwave first form?

Answer 25

Wing root

Question 26

What are the two types of shockwave that can form on supersonic aerofoils?

Answer 26

Normal and oblique

Question 27

Which type of shock wave causes an increase in the velocity of airflow?

Answer 27

Neither, an expansion wave causes an increase in velocity

Question 28

How does the vortex generator re-energise the boundary layer flow?

Answer 28

By transferring energy from the free air flow to the boundary layer

Question 29

What would be the effect on the AOA if the slats were extended?

Answer 29

Decreases the relative AOA of the wing

Question 30

When would the boundary layer separate from the aerofoil section?

Answer 30

When the normal shockwave forms

Question 31

What are the advantages and disadvantage of the anti-balance tab?

Answer 31

A: - Increases the efficiency of the control surface D: - Requires more effort to deflect the control surface

Question 32

What detrimental effect does aerodynamic heating have on metals?

Answer 32

They lose their strength

Question 33

What is the point at which airflow over a wing is at its maximum but below the speed of sound?

Answer 33

Critical mach number

Question 34

What is the normal sweep wing angle on modern aircraft?

Answer 34

30 degrees

Question 35

What is formed at a supersonic intake to ensure good airflow to the engine?

Answer 35

Oblique shockwaves

Question 36

What level of flight control surface correct for imbalance in flight?

Answer 36

Secondary

Question 37

What causes the deflection of the tab in the balance panel trim system?

Answer 37

The difference in static pressure between the two chambers

Question 38

There is a large increase in what, behind the shock wave on an aerofoil section?

Answer 38

A large increase in static pressure

Question 39

What are the differences between a normal wing profile and a transonic profile?

Answer 39

Transonic wing has: - Flatter upper surface - More curved leading edge - Thinner trailing edge

Question 40

What happens when a shock stall occurs in the transonic region and how is it corrected?

Answer 40

- Centre of lift moves outboard on the wing and aft on the aircraft - Nose tucks under - Corrected with horizontal stabilizer (mach trim)

Question 41

Where is the centre of gravity located on a balanced control surface?

Answer 41

On the hinge line

Question 42

Extending flaps and slats will do what to the profile of a wing?

Answer 42

Increase camber and area

Question 43

How is a high speed turn controlled by flying control surfaces?

Answer 43

Aileron and roll spoilers with rudder input

Question 44

How does a horn balance surface assist control deflection?

Answer 44

Air loading assists control deflection

Question 45

The automatic trim system of the horizontal stabiliser which corrects for tuck under is called what?

Answer 45

Mach trim

Question 46

How many ailerons are fitted to large aircraft and how do they operate?

Answer 46

- four (two inboard and two outboard) | - outboard are locked out at high speed

Question 47

Aluminium can lose approximately what percentage of its strength at 250 celcius?

Answer 47

80%