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EC135 GroundSchool > Principles of Flying > Flashcards

Principles of Flying Flashcards

1
Q

What are the four forces that act upon an aircraft in flight?

A

Lift, Weight, Thrust, Drag

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2
Q

What are Newtons 1,2,3 Laws

A

1 - An object will continue moving in space at a constant velocity unless an external force is applied.
2 - if a force is applied to a body it will accelerate at a rate proportional to its mass and the force applied.
3 - For every action there is an equal and opposite reaction.

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3
Q

Where is an aircrafts centre of gravity? (CofG)

A

The poin t about which all gravitational moments add up to zero.

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4
Q

What is the equation for Newtons 2nd law?

A

f=ma

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5
Q

What is Pitch, Roll and Yaw?

A

Pitch - Nose moving up or down
Roll - Rotating left or right around longitudinal centreline
Yaw - Nose moving left or right around a vertical axis through the main rotor mast.

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6
Q

How does a vector differ from a line?

A

Both direction and magnitude

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7
Q

What is the front tip of an aerofoil called?

A

Leading Edge

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8
Q

What is the back tip of an aerofoil called?

A

Trailing Edge

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9
Q

What is the centre line in aerofoil called?

A

Chord Line

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10
Q

What is the cross in the middle of the thickest part called?

A

Centre of pressure

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11
Q

A symmetrical aerofoil has a mean chord that is?

A

Straight

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12
Q

The Angle of Attack (AoA) of an aerofoil is measured between the mean chord line and the?

A

Relative Air Flow

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13
Q

In nature, energy always flows from ( ) pressure to ( ) pressure

A

High pressure to low pressure

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14
Q

What is the lift equation

A

Lift=CL 1/2p v2 S

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15
Q

What do the components of the lift equation mean?

A

CL - Coefficient of lift
1/2p - Density of the air
V2 - Air velocity over the aerofoil
S - Aerofoil surface area

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16
Q

Will a helicopter generate the same amount of lift at 28,000ft and at sea level?

A

NO

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17
Q

The ability of a wing to provide lift, increases with its ( ) until the critical ( ) is reached (It is just one answer for both)

A

Angle of Attack

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18
Q

What are the two types of drag?

A

Zero lift drag (parasitic drag)
Lift dependant drag

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19
Q

What are characteristics of drag

A

The total of all air resistance to an object moving through it.

Acts parallel to and opposite of the flight path

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20
Q

Give three items that contribute to Induced drag (Lift dependant)

A

Surface (Skin) Friction Drag
Form Drag
Increased Angle of Attack

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21
Q

Give three items that contribute to Parasitic Drag

A

Extended Landing Gear
External tanks
Ordnance/Racks

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22
Q

Why is icing a hazard?

A

Increased aircraft weight
Changes the aerofoils shape
Decreases the lift being generated
Increases the drag being generated

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23
Q

What two things must be present for icing to occur?

A

Visible moisture
OAT lower than 2C

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24
Q

Wing tip vortices are what?

A

Two counter rotating cylindrical vortices

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25
Q

What are hazards of Wake Turbulance on a following aircraft?

A

Induced Roll and Yaw
Especially dangerous during take of and landing
Rare but can cause structural damage

26
Q

What Gas Turbines commonly used in aviation?

A

Turbojet (F18)
Turboprop (PC21)
Turboshaft (Helicopter)
Turbofan (Airliners)

27
Q

What is the work cycle of a gas turbine engine?

A

SUCK SQUEEZE BANG BLOW

28
Q

What are the 4 sections of a gas turbine?

A

Intake
Compressor
Combustion
Turbine/Exhaust

29
Q

When does the spark occur in a combustion chamber?

A

Engine start

30
Q

Give an example of a conventional helicopter layout

A

MH-60R

31
Q

Why is the tail rotor required for in convential helicopters?

A

Torque reaction

32
Q

What is a teetering main rotor head?

A

Semi-Rigid rotor head (HUEY)
Simple and cheap
Prone to mast bumping

33
Q

What are the characteristics of a fully articulated rotor head?

A

They are extremely complex and heavy and as a result are used primarily on larger helicopters.

The freedom of movement provided by mechanic hinges and bearings reduces vibration and rotational stress.

34
Q

What are the characteristics of a rigid rotor head?

A

Simple and cheap
Flexible structures to allow blade movement

35
Q

The manufactured twist in rotor blades is called what?

A

Washout

36
Q

What is a defining characteristic of an assymetrical aerofoil main rotor blade?

A

Has a curved mean chord line

37
Q

Describe the main rotor disk

A

Circular area swept by main rotors

38
Q

Relative airflow vector for a rotary wing BVD is made up of what two components?

A

Rotational airflow & Induced Flow (IF)

39
Q

Induced flow is caused by what?

A

Drawing air from above the rotor

40
Q

The combination of Induced flow and rotational airflow creates what?

A

Relative airflow

41
Q

Describe the path of the rotorblades during rotation

A

Tip Path Plane

42
Q

What is the angle between the plane of rotation and the feather axis?

A

Coning angle

43
Q

Total reaction is created by what?

A

Rotor Thrust and Rotor Drag

44
Q

What is the opposing force to Rotor Drag?

A

Torque

45
Q

The cockpit flight control changes the pitch angle of each main rotor blade individually as they cycle round the rotor mast

A

Cyclic

46
Q

This cockpit flight control changes the pitch angle of all the main rotor blades at the same time

A

Collective

47
Q

What is the swashplate assembly composed of?

A

Stationary (Control ring in EC135)
Rotating (Bearing Ring in EC135)

48
Q

Which swashplate is used to transfer the cyclic and collective commands to the rotor blades through the Pitch Control Links?

A

Rotating

49
Q

Which swashplates are raised/lowered when the pilot raises and lowers the collective?

A

Both

50
Q

Why are there two cyclic control rods connected to the stationary swashplate?

A

One for pitch, one for roll

51
Q

Four items that affect coning angle

A

Rotor RPM
Rotor thrust produced (blade pitch)
Weight of the helicopter
Dynamic loading due to manoeuvering (G Force)

52
Q

To move the aircraft laterally we must tilt the…

A

Total Rotor Thrust vector

53
Q

The 90degree lag between control input and the response by the rotor is termed

A

Phase Lag

54
Q

Phase Lag can be compensated for by…

A

Advance Angle alone or,

Advance Angle and Control rigging

55
Q

Flapping to equality of lift is…

A

Blade movement which equalises rotor thrust across the disc

56
Q

Due to the principle of conservation of angular momentum, when rotor blades are coned up the RPM will…

A

Increase

57
Q

Which conventional rotor head design would give a pilot the quickest response time?

A

Rigid/Semi-Rigid rotor head

58
Q

Three metrics to measure Control Power

A

Immediacy (Time delay)
Rate (roll or pitch rate)
Control movement required

59
Q

The cockpit flight control that allows the pilot to changethe pitch of angle of all the TAIL rotor blades collectively in order to provide heading control.

A

Yaw pedals

60
Q

Yaw pedals control pitch of the tail rotor blades to: (4 answers)

A

Counter main rotor torque

Overcome frictional forces in the drive train during autorotation

Provide heading control in the hover

Provide yaw control (balance) in forward flight

EC135 GroundSchool (10 decks)

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