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Rotors and props MISC > MISC > Flashcards

MISC Flashcards

1
Q

What is the difference between effective and geometric pitch known as

A

Slip

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2
Q

What is the coriolis effect

A

When the centre of mass moves closer to the centre of rotation the rotational speed increases

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3
Q

What is the purpose of a transmission

A

Convert low torque, high RPM engine power into low RPM high torque

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4
Q

What are 5 propeller safety devices

A 
Pitch lock
Auto feather
Prop brake
Negative torque system
De coupling
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5
Q

How is flapping and dragging achieved in a fully rigid rotor system

A

Blade flex

Elastomeric bearing

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6
Q

What is thrust bending force

A

Thrust bending force exerts a pressures that tends to bend the propeller tips forward

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7
Q

Which force acting on a propeller tries to flatten the blade out

A

centrifugal twisting moment

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8
Q

What is torque reaction

A

The aircraft wants to roll in the opposite direction to the propellers rotation

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9
Q

Where are blade stations measured from

A

Center or rotation

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10
Q

What are the two iced removal methods for propellers

A

Electrical heating elements

Chemical

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11
Q

What does the dome ASSY house

A

pitch change mechanism

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12
Q

How is dsymetry of lift countered

A

Flapping to equality

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13
Q

What is the purpose of a blade cuff

A

improve airflow around the shank

send cooling air to the engine nacelle

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14
Q

What three purposes does a propeller hub serve

A

Hold blades in place

Secure prop to shaft

Transfer torque from engine into thrust

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15
Q

How is coning angle measured?

A
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16
Q

What does spanwise imbalance imply?

A

One blade being heavier than the other

Corrected by adding weight

17
Q

What does chordwise imbalance imply?

A

Blades being out of alignment

Corrected by sweeping the blades

18
Q

What does vertical imbalance imply?

A

Out of track rotor

Occurs when the blades are not following the same tip path plane

Corrected by altering either the blade trim tab or pitch change link

19
Q

What are the 3 main components of a governer?

A

Fly weights

Pilot valve

Pump

20
Q

How does a propeller produce thrust

A
21
Q

What 2 things do blade cuffs do?

A
22
Q

What are the 3 purposes for the barrel assy?

A
23
Q

What is the difference between centrifugal twisting moment and aerodynamic twisting moment?

A
24
Q

what indicates an imbalanced propeller whilst vertically statically balancing?

A
25
Q

Three purposes or the governor system?

A
26
Q

What are the 3 ranges of vibration?

A
27
Q

What is induced flow?

A
28
Q

How does the tail rotor compensate for dissimilar of lift

A

flapping to equality

29
Q

Explain slip

A

The distance between effective and geometric pitch

30
Q

Define the term tip path plane

A

the plane connecting the rotor blade tips as they rotate.

31
Q

What are 3 aerodynamic fairings around the prop assy

A

Front spinner
Rear spinner
Afterbody

32
Q

What is the purpose of flyweights in a governor

A

Sense engine speed

33
Q

What is the pumps purpose in a governor

A
34
Q

What is the purpose of a pilot valve in a governor

A
35
Q

What does the front spinner do

A

Aerodynamic fairing

Houses the pitch change assy

36
Q

What absorbs flapping and lead/lag forces in a rotor system

A

Damper

37
Q

2 types of blades stations and how are they measured

A

Normal and master

Normal is measured from the centre of rotation

Master is a specific known point on a blade used for maintenance

38
Q

What is the difference between ground effect and induced airflow

A

Induced flow is the downward vertical movement of air through the rotor system due to the production of lift, often referred to as downwash

In Ground Effect is where the downwash of air from the main rotor is able to react with a hard surface (the ground), and create a cushion of air in providing more lift with less engine power required

39
Q

What is translational lift

A

The helicopter flies out of its dirty downwash and into clean air

The undisturbed clean air increases air increases lift

The additional lift will be cancelled out eventually due to an increase in drag

Rotors and props MISC (1 decks)

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