Army Sift Flashcards

Front 1

A helicopter is a type of:

Back 1

Rotorcraft

Front 2

Helicopter Turbine engines produce (more/less) thrust per pound than piston engines

Back 2

More

Front 3

The 4 main forces acting on a helicopter are

Back 3

Lift, Weight, Thrust, and drag

Front 4

Helicopters have between ___ and ___ main rotor blades

Back 4

2 and 6

Front 5

The function of the fly bar is:

Back 5

to decrease crosswind thrust on the blades and enhance flight stability

Front 6

Many helicopters have a horizontal stabilizer located on:

Back 6

the tailboom

Front 7

The purpose of the tail- rotor system is

Back 7

to produce an anti-torque force acting perpendicular to the helicopters longitudinal axis

Front 8

A pilot controls a helicopter using

Back 8

Pedals, collective, throttle, and cyclic

Front 9

From a physics perspective, the ___________ force is deemed to act through a helicopters ___________.

Back 9

Total weight, Center of Gravity

Front 10

what happens when the pilot banks the aircraft causing it to turn?

Back 10

The machines weight increases

Front 11

In the case of Helicopters, lift is produced by _______ moving through the air at a speed sufficient enough to create a ____________

Back 11

Airfoils, Pressure Differential

Front 12

Thrust acts __________ to the aircrafts ___________.

Back 12

parallel, Longituginal axis

Front 13

Profile drag consists of _________ created by __________ and _____________.

Back 13

Skin Friction, Surface imperfections, form drag

Front 14

Vortices produced by spinning rotor blades create

Back 14

induced drag

Front 15

when plotted on a graph, L/DMAX is the point where the helicopter _________________.

Back 15

Total lift to drag ratio is the greatest

Front 16

A helicopters potential energy us affected by

Back 16

the aircrafts height above the ground

Front 17

what factors affect the lift produced by spinning rotor blades

Back 17

Airfoil coefficient of lift, Air density, blade area

Front 18

what happens when the main rotor blades spin rapidly

Back 18

the upper and lower sides of the blade experience a difference in pressure

Front 19

Newtons Third Law of Motion applies to Helicopters because:

Back 19

The spinning main rotor makes the aircraft try to spin in the opposite direction

Front 20

when the pilot pushes the cyclic forward

Back 20

the main rotor disc tilts forward

Front 21

For helicopter with the counter clockwise spinning rotor disc the __________ airflow happens when each blade reaches the _________ position

Back 21

Maximum, 3 o'clock (right)

Front 22

On the advancing rotor blade, Lift _____ and the blade ____________

Back 22

Increases, moves upward

Front 23

the angle between the _________ of a rotor blade and its direction of motion relative to the air is the ____________

Back 23

Chord line, Angle of attack (AOA)

Front 24

the angle of incidence is between the _______ of each blade ant the rotor systems _____________

Back 24

chord, plane of rotation

Front 25

when the engine ________, a clutch mechanism called a _______________, disconnects the engine from the main rotor, allowing it to spin freely

Back 25

Fails, Freewheeling Unit

Front 26

During an autorotation in forward flight, the rotor disk takes in ___________ air and the Driven, Driving , and stall regions of each blade move ________ along its length (span), but only on the _______ side of the disk

Back 26

Upward flowing, outboard, retreating

Front 27

when there is to much lift, the rotor blades will

Back 27

Flap

Front 28

Centrifugal force _______ spinning rotor blades _______.

Back 28

Pulls, Outward

Front 29

If left uncorrected, greater lift produced by the advancing side of the rotor disk compared to the lift created by the disks retreating side could make the helicopter _______

Back 29

Uncontrollable

Front 30

the driven region is _______ the blade tips and normally ____ percent of the radius

Back 30

nearest, 30

Front 31

the _____ region is normally between a blades _______ and ________ regions

Back 31

Driving, stall, driven

Front 32

Helicopters experience (ETL) effective translational lift while transitioning to forward flight at approximately __ to __ knots

Back 32

16 to 24

Front 33

Maximum ground effect occurs during a hover up to a height equal to _____ percent of the main rotors diameter

Back 33

100

Front 34

A pilot can worsen a helicopters pendular action by

Back 34

over controlling the aircraft

Front 35

the phenomenon of a helicopter sinking into its own down wash is called

Back 35

settling with power

Front 36

a lighted heliport may be identified by

Back 36

a green, yellow, and white rotating beacon

Front 37

during a hover a helicopter tends to drift in the direction of tail rotor thrust, this movement is called

Back 37

translating tendency

Front 38

the upward bending of the rotor blades resulting from the combined forces of lift and centrifugal force is know as

Back 38

coning

Front 39

the helicopter center of gravity is usually located

Back 39

a short distance fore and aft of the main rotor mast

Front 40

the lift differential that exists between the advancing main rotor blade and the retreating main rotor blade is known as

Back 40

dissymmetry of lift

Front 41

ground resonance is most likely to develop when

Back 41

a series of shocks causes the rotor system to become unbalanced

Front 42

the proper action to initiate a quick stop is

Back 42

lower collective pitch apply aft cyclic

Front 43

take off from a slope in a skid type aircraft is accomplished by

Back 43

bringing the aircraft to a level attitude before completely leaving the ground

Front 44

density altitude at standard conditions is

Back 44

29.92in Hg and 15 degrees C

Front 45

a pilot should consider using a running takeoff when

Back 45

gross weight or density altitude prevents a sustained at normal hover altitude

Front 46

the proper procedure for a slope landing with skid type gear is

Back 46

when parallel to the slope slowly lower the upslope skid to the ground prior to lowering the downslope skid

Front 47

Combination of factors the reduce helicopter performance the most

Back 47

high altitude, high temperature, and high humidity

Front 48

Most favorable conditions for helicopter performance

Back 48

low- density altitude, light gross weight, and moderate to strong winds

Front 49

which statement is true regarding the forces acting on an aircraft in a steady flight condition

Back 49

Lift equals Weight, Thrust equals Drag

Front 50

If a hard surfaced runway is labeled 22, the opposite direction of the same runway is labeled

Back 50

4

Front 51

The force that counteracts an aircrafts weight and causes the helicopter to rise, produced by airfoils moving at a speed to create a pressure differential between the two sides of the airfoil

Back 51

Lift

Front 52

What is the aircrafts forward force

Back 52

Thrust

Front 53

Opposes thrust, rearward acting force caused by airflow passing over aircraft structure

Back 53

Drag

Front 54

What are three types of drag

Back 54

Profile, Induced, Parasite

Front 55

The angle between the chord line and the direction of motion relative to the air

Back 55

Angle of Attack (AOA)

Front 56

Angle between the chord line of each blade and rotor systems plane of rotation

Back 56

Angle of Incidence (AOI)

Front 57

To much lift causes

Back 57

Blade Flapping

Front 58

Distance from the tip of the rotor blade to the center of the drive shaft

Back 58

Blade span

Front 59

distance between leading and trailing edges along the chord line is

Back 59

Chord

Front 60

(Propeller Region) nearest to blade tips normally consists of 30% of radius

Back 60

Driven Region

Front 61

effect of aircraft shedding vortices and flying into undisturbed air, as speed increase it becomes more effective

Back 61

Effective Translational Lift (ETL)

Front 62

as rotor blades spin they create relative winds, as blades rotate air accelerates over airfoils and is projected downward moving large amounts of air vertically and down through rotor system

Back 62

induced flow

Front 63

cushion of air beneath moving airfoils, provides additional lift when close to the ground

Back 63

In Ground Effect

Front 64

Helicopter is suspended from a single point in space and swings like a pendulum

Back 64

Pendular action

Front 65

flow of air in relation to a helicopters blades moves in a direction opposite of aircraft and spinning rotor blades

Back 65

relative wind

Front 66

as blades spin the produce a rotational relative wind also know as

Back 66

tip path plane

Front 67

VORTEX Ring State, occurs when aircraft sinks into its own downwash

Back 67

settling with power

Front 68

inboard 1/4 of the rotor blade

Back 68

Stall region

Front 69

enhanced rotor efficiency due to aircraft transitioning from a hover to directional flight

Back 69

translational lifr

Front 70

when a force is applied to a spinning mass, the resulting effect occurs not at the force of application but 90 degrees later in the direction of rotation

Back 70

gyroscopic procession

Front 71

when an aircraft climbs to an altitude that exceeds the diameter of the main rotor it is said to be

Back 71

Out of Ground Effect (OGE)

Front 72

If a Single main rotor bladed helicopter rotating in the counter clockwise direction is moving forward the advancing blade will be in

Back 72

the right half of the rotor disc

Front 73

How do forces acting on an aircraft react in steady flight conditions

Back 73

Lift equals weight, thrust equals drag