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IERW - Schmitt > Rotary Wing, Weather Exam > Flashcards

Rotary Wing, Weather Exam Flashcards

1
Q

The METAR is a report that is issued ____.

A

Hourly

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2
Q

What kind of report is made anytime there is a significant change in the weather at the observation station?

A

SPECI

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3
Q

The wind direction is given in degrees from ____ north and wind speed is always in ____.

A

TRUE, Knots

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4
Q

METAR KOZR 100955Z would indicate an hourly report for what time on the current date?

A

10 o`clock

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5
Q

What is atmosspheric pressure?

A

The force excerted by the weight of a column of air.

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6
Q

What is standard sea level pressure in inches of mercury?

A

29.92 INS

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7
Q

What is standard sea level temperature in °C?

A

15°C

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8
Q

What is the standard temperature lapse rate with altitude?

A

2°C/ 1000ft

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9
Q

A change in one inch of mercury pressure is equal to approx. _____ feet of altitude.

A

1000

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10
Q

Define impact pressure.

A

Static pressure plus dynamic pressure.

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11
Q

Define static pressure.

A

Ambient pressure.

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12
Q

Which instruments depend on static pressure only?

A

IVSI, altimeter

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13
Q

Which instrument depends on both impact (dynamic) and static pressure?

A

Airspeed indicator

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14
Q

What pressures affect the pitot static system?

A

Static and Dynamic

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15
Q

Name and define the three types of airspeed

A

IAS (read from the dial on the face of the instruments)

Calibrated (IAS corrected for instrument and position error)

True (CAS corrected for density error)

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16
Q

Name and explain the three errors in the airspeed indicator

A

Installation Error (Misalignment of the Pitot tube with the relative wind and position of the static vents)

Density Error (Caused by pressure and temperature changes, air less dense as altitude increases)

Instrument error (Caused by friction in the instrument)

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17
Q

Is the instantaneous vertical speed indicator (IVSI) a pressure differential measuring instrument)

A

Yes

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18
Q

What does the setting knob on the altimeter change when it is turned?

A

Kollsman setting and position of the needles

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19
Q

A change if 0.15 inch of mercury pressure is equal to ___ feet

A

150

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20
Q

Define Indicated Altitude

A

Altitude as read on the dial with a current altimeter setting

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21
Q

Define True Altitude

A

Altitude above MSL

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22
Q

Define Pressure Altitude

A

Altitude above the standard datum plane (29.92 HG or 1013.25 hPa)

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23
Q

Define absolute Altitude

A

Altitude above terrain (AGL)

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24
Q

Define altimeter setting

A

Station pressure corrected to MSL

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25
Q

Why is the altimeter setting necessary?

A

To correct for pressure changes

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26
Q

What is the maximum allowable error in the altimeter?

A

Plus or minus 75` (FAA), check specific manual for specific Airframe

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27
Q

The ______ (instrument) stops functioning properly due to pitot icing.

A

Airspeed indicator

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28
Q

What is the recommended corrective action when the static system is clogged?

A

Switch to an alternate source

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29
Q

High DA and low air density mean nearly the same thing (True or false)?

A

True

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30
Q

What causes density errors?

A

Nonstandard pressure and temperature

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31
Q

Define true airspeed

A

CAS corrected for density error

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32
Q

Which of Newtons Laws is involved?

Torque effect

A

Action/ Reaction

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33
Q

Which of Newtons Laws is involved?

More power needed to obtain a desired RPM than is need to maintain the RPM

A

Inertia

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34
Q

Which of Newtons Laws is involved?

Greater load, less acceleration

A

Acceleration

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35
Q

If the airflow atop the airfoil increases, static pressure will ___ and dynamic pressure will _____.

A

Decrease, Increase

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36
Q

Define Center of pressure

A

The point along the chord line of an airfoil through which all aerodynamic forces are considered to act

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37
Q

Define airfoil

A

Any surface designed to produce lift when air is passed over it

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38
Q

List two basic types of airfoil

A

Symmetrical and Asymmetrical

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39
Q

Define rotational relative wind as applied to an airfoil

A

That flow of air parallel and opposite to the flight path of rotating airfoil produced by the rotor blades turning about the mast

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40
Q

Define Induced flow

A

Downward flow of air through the rotor blades

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41
Q

Define resultant relative wind

A

Rotational relative wind modified by induced flow

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42
Q

How is the angle of incidence measured in a rotary-wing a/c?

A

The angle between the chord line of an airfoil and the plane of rotation (tip path plane [TPP])

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43
Q

Define angle of attack (AoA)

A

The angle between the chord line of an airfoil and the resultant relative wind

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44
Q

Which flight control changes the angle if incidence differentially around the rotor system?

A

Cyclic pitch control

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45
Q

With an increase in the speed of air over a surface, what happens to dynamic and static pressure?

A

Dynamic pressure increases while static pressure decreases

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46
Q

Time TAF

A

Issued every 6 hours, Valid (Military) for 30 hours

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47
Q

Most critical atmospheric parameters

A

Temperature (most critical) and Pressure

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48
Q

Components of atmospheric air density

A

Pressure, Temperature, Humidity

49
Q

Standard Temperature Rule

A

If temperatures are colder than standard temperature, than true Altitude and DA are always lower and vice versa!

50
Q

Density Altitude Rule

A

Higher Pressure equals more dense air, but equals low DA and vice versa!

51
Q

The four forces of flight

A

Lift, Weight, Thrust and Drag

Lift as it opposes Weight and Thrust as it opposes Drag

52
Q

Newtons First Law

A

Inertia

“A body at rest will remain at rest and a body in motion will remain in motion at the same speed and in the same direction unless acted upon by an external force”

Example: “Requires more torque to accelerate to 100% RPM than to maintain 100% RPM”

53
Q

Newtons 2nd Law

A

Acceleration

“A change in velocity with respect to time
F=m*a”

Example: “Rate of acceleration to 100% RPM from Engine Idle dependent upon amount of force applied through introduction of fuel and oxygen”

54
Q

Newton 3rd Law

A

Action/ Reaction

“For every Action the is an equal and opposite Reaction”

Example: “Main rotor turns counterclockwise forcing the nose of helicopter to turn clockwise.”

55
Q

Bernoullis Principle

A

Within a confined system (with a incompressible fluid or gas), total energy remains the same.

56
Q

Chord

A

Provides longituidinal dimension and is contained in the airfoil section

57
Q

Chord line

A

Imagninary line which extends through the leading edge on which all angles and winds are measured

58
Q

Effects regarding relative wind on the advancing blade after 6 o’clock

A

Advances into the relative wind
Blade speeds up
Blade flaps up, max. 3 o’clock

59
Q

Effects regarding relative wind on the retreating blade after 12 o’clock

A

blade retreats from relative wind
blade begins to slow down
blade begins to flap down, max. flap down 9 o’clock

60
Q

Induced Flow/AoA Rule

A

As induced Flow increases, AoA decreases and less Lift is produced and vice versa!

61
Q

List the two components of aerodynamic Force

A

Lift and Drag

62
Q

Describe the relationship of lift and resultant relative wind

A

Perpendicular

63
Q

Describe the relationship between Drag and resultant relative wind

A

Drag is parallel to and in the same direction as the resultant relative wind

64
Q

Match with type of drag

Rotor-tip vortices
Lift and total aerodynamic force tilting rearward on the airfoil
Skin friction of the fuselage
Skin friction of the airfoil
Non-streamlined fuselage

A

induced
induced
parasitic
profile
parasitic

65
Q

Which type of drag decreases with increasing airspeed

A

induced

66
Q

Which type of drag increases with increasing airspeed

A

Parasite

67
Q

Define Dissymmetry of lift

A

Differential lift between advancing and retreating halves of the rotor disk

68
Q

What causes the advancing blade to flap up

A

increase in lift

69
Q

How does the helicopter compensate for dissymetry of lift?

A

Flapping

70
Q

How does the pilot compensate dissymmetry of lift

A

cyclic feathering

71
Q

Define blowback

A

Change in attitude of the rotor system

72
Q

Which of forces of the lift equation can the pilot control?

A

Coefficent of lift thru angle of attack and relative wind velocity or airspeed

73
Q

What are the three factors in air density that will affect lift?

A

Pressure, Temperature, Humidity

74
Q

A semi-rigid disk tilts relative to the ____

A

Mast

75
Q

A articulated disk tilts relative to the ____

A

Hub

76
Q

Define centrifugal force

A

Outward force produced whenever a body moves in a curved path

77
Q

Define rotor blade coning

A

Upward flexing of the rotor blades

78
Q

Rotor blade coning is a compromise between which to forces

A

Lift and Centrifugal forces

79
Q

Define gyroscopic precession

A

When a force is applied to a rotating body, it will manifest 90 degrees after application in the direction of the rotation

80
Q

Why is blade twisting necessary?

A

To distribute the lifting force more evenly along the blade

81
Q

Define translating Tendency

A

The Tendency of a single main rotor helicopter to drift laterally in the direction of tail rotor thrust

82
Q

Lift four methods to overcome translating tendency

A

Mast/ Transmission tilting
Cyclic rigging
Pilot induced left cyclic
Automatic/ Electronic, preprogrammed stability measures

83
Q

List the four rotor blade actions

A

Rotating, Flapping, Hunting, Feathering

84
Q

Describe the relationship of total force to the TPP (tip path plane)?

A

Perpendicular

85
Q

When the rotor disk is tilted, what are the two components of total force

A

Lift, Thrust

86
Q

What are the two flight conditions

A

Balanced/ Unbalanced

87
Q

At what altitude would the aircraft be in ground effect

A

Less than one rotor diameter (Ground to Rotor disk)

88
Q

Loss, or apparent loss, of ground effect is caused by?

A

An altitude greater than one rotor diameter
Trees, bushes
Tall grass or uneven terrain
Hovering over water
Beginning of translational movement
Hovering into the wind

89
Q

Define effective translational lift

A

When the rotor completely outruns the reciculation of old vortices and begins to work in relatively undisturbed air

90
Q

Effective translational lift occurs at an airspeed of ____

A

16 - 24 KIAS

91
Q

Transverse Flow effect occurs at an airspeed of ____

A

10 - 20 KIAS

92
Q
A
  1. Tip path plane or Plane of rotation
  2. Chord line
  3. Axis of Rotation
  4. Rotational relative wind
  5. Induced Flow
  6. Angle of Attack
  7. Resultant relative wind
  8. Angle if Incidence
  9. Lift
  10. Drag
  11. TAF (Resultant Force)
93
Q

Define settling with power

A

A condition of powered flight in which the helicopter settles in its own downwash (vortices)

94
Q

List the three simlutaneous conditions required for settling with power

A

A vertical or near vertical descent esceeding 300 ft/min
20 - 100% Power used by engines
Airspeed less than ETL

95
Q

List the required recovery of settling with power

A

Increase airspeed with cyclic
Reduce collectiv as altitude permits
Adjust rotor RPM to normal operating range

96
Q

Define autorotation

A

Flight condition with no power supplied and the main rotor is driven only by the relative wind

97
Q

Describe how the pilot prevents a rotor rpm overspeed during an autorotation with turn

A

Raise the collective

98
Q

List the three conditions required for a dynamic rollover

A

Pivot Point
Rolling motion
Exceeding the critical angle

99
Q

Dynamic rollovers occurs due to a combination of which two factors?

A

Physical and Human

100
Q

Which control input is required to recover from dynamic rollover on level ground?

A

Smooth, moderate collective reduction

101
Q

Operating at what speed is most likely to produce retreating blade stall?

A

Excessive Speed

102
Q

Describe the symptoms of retreating blade stall in a single rotor helicopter

A

Pitch nose up
Roll towards left

103
Q

Describe the recovery procedure from retreating blade stall

A

Reduce collective
Regain A/C control

104
Q

Retreating blade stall and excessive coning share which causes?

A

High GW
High “G” maneuvers
Low Rotor RPM
Turbulances

105
Q

Cyclic feathering does what?

A

Does NOT change overall lift of the rotor system (increases one half, decreases other)

106
Q

Collective Feathering is what?

A

Pitch changes applied equally and simultaneously to all blades

107
Q

What reduces impact of Induced Flow?

A

Airspeed

108
Q

Hunting does?

A

Reduces stress of the blades caused by flapping

109
Q

Define Total force

A

Single Force emitted troughout the center of the rotor disk

110
Q

Define Ceiling

A

Lowest Layer of Broken or Overcast or vertical visibility if sky is obscured

111
Q

Three cockpit setting of METAR

A

Ceiling, wind, visibility

112
Q

Atmospheric Pressure is changed by

A

Temperature, Pressure and Humidity

113
Q

What is and what provides the most dominant force for the rotor system?

A

It is the centrifugal force and it provides rigidity

114
Q

Regarding advancing and retreating blade:

A

Max. Flap Up/ down applied at 3 and 9 o’clock

115
Q

Components of TAF

A

Lift and Drag

116
Q

Components of Total Force

A

Lift and Thrust

117
Q

Pressure table

A
118
Q

Pressure temperature conversion table

A

IERW - Schmitt (30 decks)

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