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Propellers > Midterm > Flashcards

Midterm Flashcards

1
Q

How much brake horsepower is converted to thrust horsepower?

A

85%

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2
Q

How much can propeller efficiency vary by?

A

50-87%

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3
Q

What factors does the amount of thrust depend on?

A
  • angle of attack
  • speed
  • shape of airfoil
  • propeller efficiency
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4
Q

How are propellers classified?

A

-according to position on aircraft and pitch

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5
Q

What is mach 0.87?

A

565 knots

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6
Q

What is mach 0.85?

A

prop efficiency begins to decrease dramatically when tip velocity approaches or exceeds this

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7
Q

Explain thrust bending force

A
  • caused by thrust loads
  • compression and tension acting upon blades
  • bends blades forward in line of flight
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8
Q

Where do blades try and stay in the centrifugal twisting moment?

A

-try to stay in parallel rotation to the propeller plane of rotation

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9
Q

What 3 forces cause the propeller to vibrate when a propeller is connected to an engine

A
  • thrust
  • aerodynamic
  • mechanical
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10
Q

What is the resonant frequency?

A

The frequency of which the system will vibrate if it is excited by a single pulse

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11
Q

What are the hardwoods used to manufacture aircraft propellers?

A
  • birch
  • ash
  • maple
  • cherry
  • oak
  • black walnut
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12
Q

In wooden propellers, all types and laminations must be free of

A
  • grain irregularities
  • knots
  • air pockets
  • Insect damage
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13
Q

How many layers are wooden propellers fabricated from?

A

5-10

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14
Q

What do laminated layers glued together form?

A

blank

the rough cut and allowed to season

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15
Q

Dimensions, pitch and shape are milled from the laminated wood using

A

airfoil jigs and blade station measurements

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16
Q

In some cases the last —- inches of the blade has a fabric covering to reinforce the thinner section of the propeller tip

A

12-15

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17
Q

What is applied to wooden propellers to prevent moisture ingress?

A

Clear water proof varnish

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18
Q

What colour paint is used on the tip of wooden propellers?

A

Red or white

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19
Q

In model number 70D42, what is 42?

A

Geometric pitch as 75% radius station

20
Q

Which direction are wooden propellers stored?

A

horizontally

for even moisture distribution - prevents warping

21
Q

Aluminum round tip

A
  • large arc

- no advantage for tip disturbances

22
Q

aluminum Square/klip tip

A
  • shorter than round

- lower rpm, quieter

23
Q

aluminum Scimitar sweptback

A
  • reduces tip vortices

- higher speed

24
Q

aluminum q tip

A
  • 90 degree bend at tip towards face
  • quieter
  • reduces tip vortices
25
Q

What are the three mount types of aluminum propellers

A
  • splined shaft
  • tapered
  • flange
26
Q

Aluminum propellers Field Repair of Aircraft Propellers Part _ Standard _ Appendix _

A

Part 5 Standard 571 Appendix D

27
Q

How are aluminum propellers balanced?

A

Vertically and horizontally

28
Q

When you paint an aluminum propeller, what does the paint further protect it from?

A

corrosion and FOD

29
Q

What materials can be used in composite?

A
  • core of wood, honeycomb or rigid foam and reinforcing shank
  • fiberglass or carbon fibre and aramid fibre
30
Q

In composite propellers, wear occurs from what?

A
  • high rpm in rain or sandy areas
  • fod on taxis and runways
  • delamination when damage is left unrepaired which allows moisture to enter
31
Q

How are composite propellers balanced (direction)?

A

Statically in the horizontal plane

32
Q

How (method) are composite propellers balanced?

A

-by adding lead wool to centrally located balance tube in metal blade shank

33
Q

On a composite propeller, what does a finish covering of polyurethane paint protect the blade against?

A

erosion and uv damage

34
Q

What is the constant speed range of a constant speed propeller determined by?

A

the high and low pitch stops

35
Q

For constant speed propellers, the throttle can be placed anywhere between the min and max setting based on the required ——-

A

manifold pressure

36
Q

What are the 3 main functions of the governor?

A
  • boosts engine oil pressure
  • senses rotational speed of engine
  • controls the amount of oil to the propeller hub
37
Q

Engine oil is boosted in the governor by an _____ which is geared to the engine

A

integral gear type pump

38
Q

What is the normal engine oil pressure and what does it increase to?

A

normal 60, increase to 180 to 300

39
Q

What is the name of the thing that senses engine speed in constant speed propeller>

A

propeller governor

40
Q

The propeller governor oil is controlled by the _____

A

pilot valve

41
Q

The governor is operated by the pilot with the ______ in the flight deck

A

propeller lever

42
Q

A combination of ___ and ____ in the hub allowed the propeller to maintain a constant speed for constant speed propeller

A

speeder spring and oil pressure

43
Q

THe ____ regulates the flow of oil based on the position of the flyweights

A

governor

44
Q

There is a failsafe incorporated into the governor in the form of a

A

return spring

45
Q

What is the RPM time for initial climb

A

the time to bring the rpm back from peak to around max continuous rpm

Propellers (1 decks)

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