Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

SMA > Block 2 Rotary Wing Aerodynamics > Flashcards

Block 2 Rotary Wing Aerodynamics Flashcards

1
Q

__________ of helicopters and airplanes are basically the same, while __________ __________ differ widely from those of an airplane.

A

Aerodynamics

Flight Characteristics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

_________ ____ _________(___________) depends on the magnitude of the unbalanced force and mass of the body

A

Rate of change (acceleration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

____________ provides the basis for all helicopters flight- vertical, forward, backward, sideward or hovering

A

Rotary Wing Aerodynamics - Balance of Forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Total force generated by a rotor system is always _____________ to the tip-path plane.

A

Perpendicular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Force is divided into what two components?

A

lift and thrust

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The ________ component of a rotary wing aircraft acts horizontally to accelerate or decelerate the helicopter in the desired direction

A

Lift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

On a rotary wing aircraft, thrust may be directed in the desired direction by…

A

tilting the tip-path plane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

At __________, all opposing forces are in balance and the helicopter remains stationary

A

hover

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

At hover, total force is acting opposite to the helicopter’s ________

A

weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

To move a helicopter in some direction, a ________ must be applied to cause an _________ __________

A

force

unbalanced condition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The wind produced by the rotational velocity of the rotor blade, induced flow caused by the production of lift and the movement of the helicopter through the air mass is:

A

Relative Wind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Relative Wind is produced by:

A
  1. The rotational velocity of the rotor blade
  2. Induced flow caused by the production of lift
  3. The movement of the helicopter through the air mass
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Relative wind moves in a ________, but __________ direction to the airfoil

A

Parallel

Opposite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When a helicopter maintains a constant position over a selected point, usually a few feet above the ground

A

Hovering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Rotor tip vortex is also known as:

A

Air swirl at the tip of the rotor blades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

There are high-power requirements for hovering due to:

A

The continuous creation of new vortexes and ingestion of existing vortexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

A condition of improved performance encountered when operating near the ground

A

In-ground effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The reduction of the velocity of the induced air flow

A

Distinct phenomena 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Distinct phenomena 2

A

Reduction of the rotor tip vortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Type of hover in which the rotor blades move large volumes of air in a downward direction called induced flow.

A

Out-of-ground effect hover

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Out -of-ground effect hover requires a ______ _______ setting

A

high power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

A single-rotor helicopter has the tendency to drift laterally to the ______ during hover

A

right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The tendency of a single-rotor helicopter to drift laterally to the right during hover.

A

Translating tendency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Lateral tilt results in a main rotor force to the ______ that compensates for the tail rotor thrust to the ______

A

left

right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

As the incoming wind enters the rotor system, turbulence and vortexes are left behind, the flow of air becomes more horizontal, improving performance.

A

Transitional lift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

When a helicopter transitions from hover to ________ _______, the tail rotor becomes more aerodynamically efficient.

A

forward flight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

During transitional lift, __________ increases due to the tail rotor working in progressively less turbulent air as speed is increased.

A

efficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

During transitional lift, more thrust is produced causing the aircraft’s nose to _______ _______ due to the main rotor turning __________________

A

yaw left

counterclockwise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

During a helicopter takeoff, the _________ _________ must be applied as speed increases to correct for left yaw tendency

A

right pedal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The difference in lift between the advancing half of the rotor disk and the retreating half

A

Dissymmetry of lift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

During dissymmetry of lift, the blade passing the tail and advancing reaches a maximum at the ________ position

A

3 o’clock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

During dissymmetry of lift, the blade speed decreases and reaches a minimum airspeed at the _________ position

A

9 o’clock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Downward force applied at point A results in downward movement response at point B, and upward force applied at point C results in upward response movement at point D. This is called:

A

Gyroscopic precession (refer to figure 2-20)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

___________ affects the rotor disk when force is applied at a given point

A

(gyroscopic) precession

35
Q

The rotor will always tilt in the direction in which the _______ ________ is moved.

A

cyclic stick

36
Q

When the engine fails or is disengaged from the rotor system, a ______ must be used to sustain rotor RPM so controlled flight can be continued to the ground.

A

force

37
Q

During autorotation, the pilot gives up __________ at a controlled rate in return for _________ to turn the rotor at an RPM that provides aircraft control

A

altitude

energy

38
Q

When an engine fails or is disengaged from the rotor system, a force must be used to sustain rotor RPM so controlled flight can be continued to the ground.

A

Autorotation

39
Q

During autorotation, as altitude decreases, ________ _________ is converted to __________ __________ and stored in the turning rotor

A

potential energy

kinetic energy

40
Q

During autorotation, the pilot uses _______ _______ to cushion the touchdown when nearing the ground

A

kinetic energy

41
Q

Entry into ______________ is performed following loss of engine power

A

autorotation

42
Q

Indications of power loss are:

A

Rotor RPM decay and an out-of-trim condition

43
Q

During entry into autorotation, establish a _________ at the proper airspeed depending on the helicopter and its gross weight. RPM should be stabilized.

A

glide

44
Q

Autorotation RPM is a _______ _______ _________ than normal operating RPM

A

few turns higher

45
Q

Rate of descent and RPM are stabilized and the helicopter descends at a constant angle. This is called:

A

steady-state descent

46
Q

During steady-state descent, the angle of attack descent is normally

A

17 to 20 degrees

47
Q

Steady-state descent depends on the following 5 things:

A 
airspeed
density
altitude
wind
helicopter
48
Q

To successfully perform an autorotative landing, reduce ________ and ____________ just before touchdown

A

airspeed

rate of descent

49
Q

During deceleration and landing during autorotation, __________ change inclines the total force of the rotor disk.

A

attitude

50
Q

During deceleration and landing in autorotation, blade _______ ______ is available to cushion the touchdown

A

kinetic energy

51
Q

During autorotation deceleration and landing, _______ ________ is applied to cushion the touchdown.

A

collective pitch

52
Q

Newton’s law of action and reaction, states that a helicopter fuselage tends to rotate in the direction ___________ the rotor blades

A

opposite

53
Q

_______ must be counteracted and/or controlled before flight is possible

A

Torque

54
Q

_______ results from the rotor’s being driven by the engine power output

A

Torque

55
Q

Torque effect must be __________ corrected

A

continually

56
Q

Torque effect rotates the fuselage in a direction opposite the main rotor and the tail rotor counteracts torque effect and provides positive fuselage heading control. This is identified as:

A

Anti-torque rotor

57
Q

An anti-torque rotor compensates for torque in the single main rotor helicopter. This is done by the _____ _______

A

tail rotor

58
Q

An anti-torque rotor produces thrust in a horizontal plane ________ to torque reaction developed by the main rotor.

A

opposite

59
Q

_________ compensate for torque variance

A

Pedals

60
Q

____ to ____ percent of the available engine power may be needed to drive the tail rotor

A

5 to 15

61
Q

The up and down movement of rotor blades is known as:

A

Blade flapping

62
Q

During blade flapping, the blade climbs or flaps upward, from change in ______ ______ and ______ ___ _______ which reduces the amount of lift that would have been generated

A

relative wind

angle of attack

63
Q

During blade flapping, as the blade loses airspeed, reducing lift causes it to settle or flap _________, thus changing its relative wind and angle of attack

A

downward

64
Q

The retreating blade must produce an amount of lift equal to that of the __________ _______

A

advancing blade

65
Q

As the speed of the retreating blade decreases with forward speed, blade angle of attack must be increased to equalize _______ throughout the rotor disk area

A

lift

66
Q

Conditions most likely to produce blade stall:

A 
High blade loading (high gross weight)
Low rotor RPM
High-density altitude
Steep or abrupt turns
Turbulent air
67
Q

Warnings of approaching retreating blade stall:

A

Abnormal vibration (shuddering)
Pitch up of the nose
Tendency for the helicopter to roll in the direction of the stalled stick

68
Q

To prevent blade stall, the helicopter must fly slower than normal when:

A

The density altitude is much higher than standard
Carrying maximum gross loads
Flying high-drag configurations, external stores, weapons, sling loads, etc.
The air is turbulent

69
Q

Procedures for correcting blade stall:

A

Decrease collective pitch
Decrease the severity of the maneuver
Gradually decrease airspeed
Increase rotor RPM

70
Q

In a severe blade stall, ______ _________ ___ ______

A

all control is lost

71
Q

Fully articulated rotors are free to move ______ and _____ in the plane of rotation independent

A

fore

aft

72
Q

Pitch angle variation causes changes in the blade drag which makes the blade _________ or _______ about the drag hinge

A

lead

lag

73
Q

This law states that a rotating body will continue to rotate with the some rotational velocity until some external force is applied to change the speed of rotation

A

Coriolis Force

74
Q

Blade lead and lag is governed by the law of:

A

Conservation of angular momentum

75
Q

Applying the principle of Coriolis force to a rotating helicopter blade, it may be stated:

A
  1. A mass moving radially outward on a rotating disk exerts a force opposite to rotation (decelerates)
  2. A mass moving radially inward on a rotating disk exerts a force in the direction of rotation (acceleration)
76
Q

__________ _____ ________ happens at high altitudes, at high gross weights, or when operating with reduced power

A

Settling with power

77
Q

Settling with power makes __________ flight possible

A

level

78
Q

Settling with power can occur at any _______ or ______ , when power required exceeds power available

A

airspeed

altitude

79
Q

Settling with power, preventing level flight at _______ ________

A

slower speeds

80
Q

An extremely critical situation that may develop at any altitude or gross weight when the airspeed is below translational lift and rate of descent is high

A

Vortex ring state

81
Q

During vortex ring state, down wash from the rotor begins to recirculate up, around and back down through the effective outer portion of the _______ _____

A

rotor disc

82
Q

During vortex ring state, ________ and ________ ____ ___ ________ may occur

A

roughness

partial loss of control

83
Q

How do you recover from vortex ring state

A

Increase forward air speed, decrease collective pitch or enter autorotation if altitude permits

SMA (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions