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M15 Ryan > M15.3 > Flashcards

M15.3 Flashcards

1
Q

What does the air intake have to allow for smooth airflow?

A

A intake nose

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2
Q

What is the shape called when the air inlet duct gets wider?

A

A divergent duct

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3
Q

What does the divergent duct use to increase static pressure?

A

Bernoulli principle

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4
Q

What happens with supersonic airflow?

A

It’s compressible so engine parameters are reversed

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5
Q

What speed should the airflow be at the compressor inlet?

A

Between Mach 0.4 and 0.7

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6
Q

How do air intakes convert decelerate airflow?

A

By converting kinetic energy to pressure energy

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7
Q

What happens to velocity and pressure in subsonic inlet ducts?

A

Velocity decreases
Pressure increases

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8
Q

What is the most efficient inlet configuration for subsonic flight?

A

The pitot type quasi - circular diffuser

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9
Q

When do you get problems with subsonic inlet ducts?

A

When a/c on ground with max thrust because of core depression

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10
Q

What does making the inlet lip rounded result in?

A

A thicker radius

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11
Q

What does having a thicker radius inlet do?

A

Reduces the risk of flow separation

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12
Q

Why are large inlet lips avoided?

A

Because it hinders performance at high speeds

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13
Q

What is fitted to an intake to minimise the issues with crosswind?

A

With cross wind components which are fitted to the intake

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14
Q

What speeds is the pitot type intake good up to?

A

Mach 1.5

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15
Q

What does the pitot tube do at transonic speeds?
And how is this done?

A

Keeps shock wave out
By using a normal shock diffuser

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16
Q

What does a normal shock wave do?

A

Increase temp pressure and decrease velocity

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17
Q

What happens when rpm is reduce?

A

The pressure in the inlet rise allows less air in.

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18
Q

What must the cross sectional area of a transonic duct allow?
And what is this called?

A

Max airflow requirements that apply to only 1 Mach number and altitude

Critical condition

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19
Q

What is super critical condition?

A

When pressure in the diffuser is decreased causing normal shock to be drawn further to the inlet

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20
Q

What is sub critical?

A

When the normal shock wave is expelled due to an increase of pressure in the diffuser

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21
Q

What is diffuser buzz?

A

Caused when there is extreme pressure fluctuations

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22
Q

What happens to the shock wave in super critical, sub critical and critical?

A

Super critical = moves closer to intake
Sub critical = moves further from intake
Critical = perfect position

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23
Q

When does a normal shock wave occur?

A

When a/c at low supersonic speeds and stands perpendicular to airflow.

24
Q

What happens to velocity and pressure in a normal shock wave?

A

Velocity drops from supersonic to sub sonic
Pressure rises

25
Q

When will a oblique shock wave occur?

A

If the airflow is forced to change direction then the shock wave will form at an inclined oblique angle

26
Q

Intake efficiency for pitot intake?

A

96 - 99%

27
Q

Intake efficacy for wing root?

A

87 - 95%

28
Q

Intake efficacy for side?

A

80 - 89%

29
Q

Intake efficacy for turbo prop annular?

A

74 - 82%

30
Q

What is the disadvantage of the normal shock diffuser?

A

Has a abrupt loss of efficiency as the Mach number increases

31
Q

How is buzz overcome?

A

With a variable geometry intake

32
Q

How is a variable geometry intake controlled?

A

With the use of a air data computer

33
Q

Where is a normal shock inlet used?

A

In low supersonic speeds

34
Q

What does a oblique shock inlet do?

A

Employs an external shock wave to slow supersonic airflow before the normal shock occurs

35
Q

What does a variable geometry air intake do?

A

Uses actuators to operate panels to employ 3 oblique shock waves and 1 normal shock wave

36
Q

What type of anti icing do engines have?

A

Thermal

37
Q

What are the 2 types of ice protection for engines?

A

Bleed air
Electrical heating

38
Q

What are the 2 types of ice protection for the spinner?

A

Hot oil
Rubber spikes

39
Q

What do anti icing valves protect against?

A

Over pressurisation
And prevent loss of power

40
Q

How is the bleed air anti icing system operated?

A

Automatically or manually

41
Q

What happens to air used for anti icing?

A

Ejected overboard via small grills

42
Q

What happens to bleed air used for anti icing in the nose cone and inlet guide?

A

Sent either to LP compressor or overboard

43
Q

How are anti icing valves operated?

A

Electrically selected, pressure operated

44
Q

The anti icing valve give indications for what?

A

Valve not in position selected
Low/ high duct pressure
Low/ high duct temp

45
Q

When is the amber light shown on the anti ice valve?

A

Until low pressure switch senses a duct pressure more then 5psi

46
Q

What a/c is the electrical ice protection system found on?

A

Turboprop a/c

47
Q

What is the electrical ice protection system used on?

A

Air intake cowlings, propeller blades, spinners and oil coolers

48
Q

What is electrical power supplied to in the electrical ice protection system?

A

Heater mats (AC or DC)

49
Q

What do continuously heated elements do?

A

Prevents ice build up on engine intake and propeller spinners

50
Q

What is intermittent heating elements?

A

Behind continuously heated elements and keeps heating whilst continuously heated is switched off

51
Q

How long does fast mode on the anti ice system work?

A

2 mins when OAT is between -6c and 10c

52
Q

How long does slow mode work in the ice protection system?

A

6 mins with OAT bellow -6c

53
Q

When does the cycling light on the anti ice system glow dim and bright?

A

To show the timer is rotating

54
Q

What are heater mats examined for?

A

Splits
Winkles
Tears
Discolouration
Security of attachment

55
Q

When must continuity and heater resistance checks be made?

A

After any repair to heater mats

56
Q

When must insulation resistance checks be made?

A

To determine if there’s any break down of insulation between heater mats

M15 Ryan (17 decks)

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