Aeroplanes 1 Theory Of Flight

Front 1

What is the boundary layer

Back 1

Thin layer of air that sticks to the part of the plane in the airflow

E.g How static ports can work

Front 2

What is free stream flow

Back 2

Not affect by the AC

The straight lines

Front 3

What is laminar flow

Back 3

Flow of air in layers.

No disruption between layers

Front 4

What is turbulent flow

Back 4

Opposite of laminar

The movement of air is chaotic.

Front 5

What is relative flow

Back 5

The moment of air relative to the AC

The air seems to be moving but really it is the AC

Front 6

What is stagnation

Back 6

Where the air is stagnant. Not moving

Front 7

What is up wash and down wash?

Back 7

Front 8

What are vortices

Back 8

Spirals of air that are generated at the wing tips. One wingtip vortex trails from the tip of each wing. Wingtip vortices are sometimes named trailing or lift-induced vortices because they also occur at points other than at the wing tips. Vortex generators like on the b757 create vortex to join the slow moving boundary layer with the fast airflow for lower stall speeds.

Front 9

What are the effects of ice?

Back 9

destroys the smooth flow of air, increasing drag while decreasing the ability of the airfoil to create lift. The actual weight of ice on an airplane is insignificant when compared to the airflow disruption it causes. As power is added to compensate for the additional drag and the nose is lifted to maintain altitude, the angle of attack is increased, allowing the underside of the wings and fuselage to accumulate additional ice. Ice accumulates on every exposed frontal surface of the airplane—not just on the wings, propeller, and windshield, but also on the antennas, vents, intakes, and cowlings. It builds in flight where no heat or boots can reach it. It can cause antennas to vibrate so that they break. The airplane may stall at much higher speeds and lower angles of attack than normal. It can roll or pitch uncontrollably.

Front 10

What is flat plate theory

Back 10

flow around an airfoil as two-dimensional flow around a thin airfoil. It can be imagined as addressing an airfoil of zero thickness and infinite wingspan.

Front 11

With changes in AOA what happens to the centre of pressure ?

Back 11

Front 12

With a change in AOA what happens to the px distribution

Back 12

Front 13

The effect of fineness ratio on aerofoils

Back 13

A wing with a high fineness ratio = skin friction.

A wing with a low fineness ratio = turbulence.

The best wing is a compromise between these two extremes to hold both turbulence and skin friction to a minimum

Front 14

How does aspect ratio effect aerodynamics

Back 14

Generally, high aspect ratio wings give slightly more lift and enable sustained, endurance flight,

low aspect ratio wings are best for swift manoeuvrability

Front 15

What effect does airspeed have on lift of an aerofoil

Back 15

Lower the speed the higher AOA

Why they use flaps when landing

Front 16

When is induced drag at the highest.

Back 16

Low speeds

High AOA (climbing)

Front 17

What are the 4 forces of flight

Back 17

4 forces of Flight. In level flight, lift equals weight and thrust equals drag when the plane flies at constant velocity. ... If the weight is greater than the lift, then the plane will accelerate downward. When the thrust becomes greater than the drag, the plane will accelerate forward.

Front 18

What is aircraft wing camber and chord line

Back 18

Front 19

What is mean aerodynamic chord

Back 19

the leading edge and trailing edge are parallel, the chord of the wing is constant along the wing's length

The average length of the chord is known as the mean aerodynamic chord (MAC). In large aircraft, centre of gravity limitations and the actual centre of gravity are often expressed in terms of percent MAC.

Front 20

What is lift coefficient

Back 20

relates the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area

How much lift a wing will give

Front 21

What is drag coefficient

Back 21

coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag.

How much drag a wing is gonna cause

Front 22

What causes induced drag

Back 22

inevitable consequence of lift and is produced by the passage of an aerofoil (e.g. wing or tailplane) through the air. Air flowing over the top of a wing tends to flow inwards because the decreased pressure over the top surface is less than the pressure outside the wing tip.

Front 23

What is profile drag

Back 23

the drag caused by the separation of the boundary layer from a surface and the wake created by that separation.

Cause by skin friction and skin drag

Front 24

What is angle of incidence

Back 24

angle of incidence (sometimes referred to as the mounting angle) is the angle between the chord line of the wing where the wing is mounted to the fuselage, and a reference axis along the fuselage.

Front 25

What is wash in and wash out

Back 25

increase of the angle of incidence at the wing tips as compared to the angle of incidence of the wing root. Washing in increases the lift, and in aircraft rigging it is one of the methods to correct for a wing-heavy condition. Washout improves the stalling characteristics of a wing, as in the wing with washout. The roots stall earlier than the tips, thus maintaining aileron control while the wing root stalls

Front 26

Where does centre of px move with a high AOA

Back 26

Forward

Front 27

What is the flight envelope

Back 27

The limits at which the aircraft operates in

Front 28

What is the structural limit VNE

Back 28

Max speed

Velocity never to exceed

Front 29

What is the structural limit VNO

Back 29

Max cruising speed

Normal operation

Front 30

What is the structural limit VFE

Back 30

Max flaps extended speed

Front 31

What is the COG expressed as a % of MAC

Back 31

Front 32

What is side slip

Back 32

Basically a cross wind landing is a side slip.

Front 33

What is wing loading

Back 33

The total weight of the AC ÷

By the area of the wings

Front 34

What is ground speed

Back 34

horizontal speed of an aircraft relative to the Earth’s surface

Front 35

What is true airspeed

Back 35

True airspeed increase as air gets thinner

The actual speed the AC is going.

Accounts for changes in temp and px

Front 36

What is indicated airspeed

Back 36

Direct measurement.

Doesn't take into account px and temp changes

Front 37

What is the purpose of an AOA detector

Back 37

a visual indication of the amount of lift the wing is generating at a given airspeed or angle of bank.

The AOA delivers critical information visually or through an aural tone to indicate an aerodynamic stall

Front 38

How does an AOA detector work

Back 38

Measures the angle between wing chord and relative wind. B757

Front 39

What is anhedral and dihedral aircraft

Back 39

Wing angles

Front 40

What is longitudinal dihedral

Back 40

the difference between the angle of incidence of the wing root chord and angle of incidence of the horizontal tail root chord

Front 41

What are tapered wings

Back 41

Tapered wings increase the aspect ratio of the wing in an aeroplane improving the lift.

Front 42

Why use sweepback wings

Back 42

delaying the shock waves and accompanying aerodynamic drag rise caused by fluid compressibility near the speed of sound

Swept wings are therefore almost always used on jet aircraft designed to fly at these speeds.

Front 43

How does angle of incidence affect stability

Back 43

reducing its drag at certain airspeeds

Front 44

What does asymmetric thrust cause

Back 44

The plane to yaw to the bad engine

Front 45

What is the gyroscopic effect

Back 45

When a single-engined aeroplane turns to the left, the nose tends to dip

When the turn is to the right, the gyroscopic effect tends to raise the nose.

Front 46

How to increase lateral stability

Back 46

A high-wing has good lateral stability

low wing has a destabilizing effect in roll.

Making the wings dihedral improves the lateral stability.

Front 47

What is longitudinal stability

Back 47

longitudinal static stability of an aircraft is significantly influenced by the distance (moment arm or lever arm) between the centre of gravity (c.g.) and the aerodynamic centre of the airplane

Front 48

What is the slip stream effect

Back 48

During takeoff, air accelerated behind the prop (known as the slipstream) follows a corkscrew pattern.

As it wraps itself around the fuselage of your plane, it hits the left side of your aircraft's tail, creating a yawing motion, and making the aircraft yaw left.

Front 49

What is positive static stability

Back 49

positive static stability tends to return to its original attitude when it's disturbed

Front 50

What is neutral static stability

Back 50

neutral static stability tends to stay in its new attitude when it's disturbed

Front 51

What is negative static stability

Back 51

continue moving away from its original attitude when it's disturbed

Front 52

What is propeller torque effect

Back 52

single-prop, tendency of the plane to turn upwards and left in response to the propeller turning.

banking the plane in the opposite direction of the propeller spin

Front 53

What is flutter in aircraft

Back 53

Flutter is a phenomenon that can occur when a structure is subjected to aerodynamic forces

Flutter in aircraft causes the wings and / or stabilizers to oscillate.

Front 54

What are the maintenance practices for flutter

Back 54

-Move CG of the wing closer to the center of twist.

-Raise the flutter freq by making the wing stiffer and lighter

-Tune shape with the help of computer simulations or wind tunnel.

-Set the max allowed airspeed below the speed at that flutter occurs.

-During test flight, check if there is no flutter in the flight envelope.

Front 55

What is Dutch roll

Back 55

Yaw dampers get rid of Dutch roll

Front 56

How to mitigate pitch-up

Back 56

use a control-canard duck neck

slats.

When slats are extended they increase wing camber and increase maximum lift coefficient.

Front 57

When AOA is increased what happens to centre of px

Back 57

Moves forward

On asymmetric wing and won't move at all on a symmetrical wing

Front 58

What effect does fineness ratio have on skin friction and turbulence

Back 58

High fineness = high friction low turb

Low fineness = low friction high turb

Front 59

What is static stability

Back 59

The ability of a displaced body to return to equilibrium

Front 60

As a subsonic aircraft speeds up CofPx moves

Back 60

Aftward

Front 61

What causes the spanwise flow of the lower wing surface to increase

Back 61

Large flap deployment

Front 62

What part of a swept wing aircraft stalls first

Back 62

Tip stalls first

Front 63

With a drop in ambient temp an aircraft service ceiling will

Back 63

Rise.

Temp drops density increases and performance increases

Front 64

What is the structural limit VA

Back 64

Max maneuvering speed