1. Fixed wing

Question 1

Define the stratosphere

Answer 1

The stratosphere is the layer of air outside the troposphere. It is from a height of 11km or 36,000ft to a height of 30km.

Question 2

Define the tropopause

Answer 2

The tropopause is the layer of air where the troposphere and stratosphere meet. It is found at a height of 11km or 36,000ft.

Question 3

What do the letters ISA stand for?

Answer 3

International standard atmosphere

Question 4

Why do we have an ISA?

Answer 4

To compare aircraft performance and calibration of altimeters.

Question 5

What conditions are assumed at sea level in ISA?

Answer 5

+15C. 1013mb. 1.226kg/m(cubed)

Question 6

Define total or stagnation pressure

Answer 6

Total or stagnation pressure is dynamic pressure + static pressure

Question 7

Define boundary layer

Answer 7

The boundary layer is the layer of air next to the aircraft that is slowed down by viscosity and surface friction.

Question 8

Define centre of pressure

Answer 8

The centre of pressure is the point on the chord line which through the total reaction acts.

Question 9

Define the lift

Answer 9

The lift is the component of the total reaction which acts at right angles to the relative air flow direction.

Question 10

Define drag

Answer 10

Drag is the component to the total reaction which acts parallel to the relative air flow direction.

Question 11

Define stall

Answer 11

Stall is when the angle of attack is increased but does not produce an increase in lift.

Question 12

Describe the boundary layer.

Answer 12

The boundary layer is in 2 forms: laminar layer and turbulent layer. The laminar layer is 0.1mm-0.2mm thick and has a relatively low drag. The turbulent layer is 5mm thick and has a relatively high drag. The transition point is where the laminar layer changes into the turbulent layer. The separation point is the point where the turbulent layer separates from the aerofoil and degenerates into drag.

Question 13

Define the troposphere

Answer 13

The troposphere is the layer of air next to the earth. It goes from the earths surface to a height of 11km or 36,000ft.

Question 14

Chord line

Answer 14

A straight line from the leading edge to the trailing edge.

Question 15

Define mean camber line

Answer 15

A lime drawn midway between the upper and lower surfaces of the aerofoil from the leading edge to the trailing edge.

Question 16

Define maximum camber line.

Answer 16

The maximum distance between the mean camber line and the chord line.

Question 17

Define angle of attack.

Answer 17

The angle created between the chord line and relative air flow direction .

Question 18

Define angle of incidence.

Answer 18

Angle of incidence is the angle between the chord line and the manufactures datum.

Question 19

Define span.

Answer 19

The distance from wing tip to wing tip.

Question 20

Define aspect ratio.

Answer 20

The ratio between the wing span and chord length.

Question 21

Define wash out.

Answer 21

A wash out is a decrease in angle of incidence towards the tip of the wing.

Question 22

Define wash in.

Answer 22

An increase in angle of incidence towards the tip of the wing.

Question 23

What is the stalling angle?

Answer 23

15 to 16 degrees

Question 24

The equation for how lift is calculated.

Answer 24

L = (p x v^2 x s x cl)/2

Question 25

The equation for how drag is calculated.

Answer 25

D = (P x v^2 x s x cd)/2

Question 26

List the seven factors that affect lift and drag.

Answer 26

``` Density Velocity of air flow Plan area Angle of attack Surface finish Aerofoil shape Coefficient of lift/drag ```

Question 27

Considering lift augmentation devices, what two factors must they increase (so that the aircraft can fly more slowly without losing too much lift)?

Answer 27

Surface area and/or coefficient of lift.

Question 28

Name the two devices fitted to the leading edge to allow aircraft to fly more slowly.

Answer 28

Slots and slats.

Question 29

What is a slat?

Answer 29

A moveable extension to the leading edge which creates a slot when extended.

Question 30

Why are flaps fitted to an aircraft?

Answer 30

To increase lift at low speeds, particularly at take off And to increase both lift and drag for landing.

Question 31

What type of flap achieves its object by increasing the area of the wing?

Answer 31

Fowler flap

Question 32

Why are Krueger leading edges, or nose flaps fitted to some aircraft?

Answer 32

To prevent leading edge separation on thin wings with sharp edges, such as the ones used on very high speed aircraft.

Question 33

3 things that a fowler flap shows when open.

Answer 33

Increased curvature, increased angle of attack and increased surface area.

Question 34

The coefficient of lift/drag is made from:

Answer 34

Angle of attack Surface finish Aerofoil shape

Question 35

What is the most effective angle for the highest wing efficiency?

Answer 35

3 to 4 degrees

Question 36

What is a slot?

Answer 36

The effect of the slot is to re energise the boundary layer.

Question 37

What types of flaps are there?

Answer 37

Plain, slotted, split, fowler, double slotted fowler, kreuger or nose flap and triple slotted fowler.

Question 38

What does the slot do to the layers?

Answer 38

It moves the TP on a bit, and moves the SP a lot towards the trailing edge.

Question 39

Comparison of a thick aerofoil to a thin aerofoil at slow speed.

Answer 39

Thick: lots of lift, lots of drag Thin: not much lift, very low drag

Question 40

Comparison of a thick aerofoil to a thin aerofoil at high speed.

Answer 40

Thick: lots of lift, massive drag Thin: enough lift, some drag

Question 41

Comparison of a thick aerofoil to a thin aerofoil, what they would be part of in the real world?

Answer 41

Thick: load carrier, short field ops Thin: high speed fighter, very long runways

Question 42

Define Mach number

Answer 42

The Mach number is the ratio of the speed of an object to the speed of sound in the same fluid.

Question 43

Define free stream Mach number

Answer 43

The Mach number of a flow sufficiently removed from an aircraft to be unaffected by it.

Question 44

Define local Mach number

Answer 44

The ratio of the speed of flow at any point on an aircraft to the speed of sound at the same point.

Question 45

Define critical Mach number

Answer 45

The free stream Mach number at which any local Mach number becomes 1.

Question 46

Define subsonic

Answer 46

All ML less than 1.

Question 47

Define transonic

Answer 47

Mixed flow - some mL less than 1, some mL more or equal to 1.

Question 48

Define supersonic

Answer 48

All ML equal to 1 or more.

Question 49

What's the problem with a shock wave?

Answer 49

Formation of shockwaves on the main plane causes a thickening of the boundary layer which separates from the wing surface at the base of the shockwave.

Question 50

Name 2 aerofoil sections that are used for supersonic?

Answer 50

Bi convex and double wedge

Question 51

What type of aerofoil is used for when an aircraft is flying just below the speed of sound?

Answer 51

Supercritical

Question 52

How can induced drag be minimised?

Answer 52

By having winglets or wings with a high aspect ratio

Question 53

Symmetrical aerofoil at zero angle of attack

Answer 53

Will not produce a vortex.

Question 54

Zero lift drag can also be known as the following:

Answer 54

Form skin and drag friction.

Question 55

The equations for level:

Answer 55

T=D L=W P=T x W

Question 56

The equations for climbing:

Answer 56

RateOfClimb: Vsin€ L = Wcos€ T =D + Wsin€ P=T x V = (D + Wsin€) x V

Question 57

The equations for diving:

Answer 57

``` L = Wcos€ D = T + Wsin€ T = D - WSin€ P = T x V = (D - Wsin€) x V ```

Question 58

The 2 types of shockwave?

Answer 58

Normal Mach wave | Oblique Mach wave

Question 59

As aircraft increases in the transonic speed range, what happens to the aircraft pitch attitude?

Answer 59

The C of P goes towards the back of the plane making the nose dive down.

Question 60

How can a designer increase the value of Mcrit?

Answer 60

Thinner wings and sweepback