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Flashcards in SIFT Study Guide Army Aviation Information Practice Test Deck (40):
1

A helicopter is

A type of rotorcraft

2

Helicopter turbine engines produce ______ thrust per pound than piston engines:

More

3

The main forces acting on a helicopter are

Lift, weight, thrust, drag

4

Helicopters typically have between __ and __ main rotor blade(s):

2,6

5

Depending on the type of helicopter, main rotor system components can include:

A stabilizer bar, upper and lower swashplates, counterweights, pitch horns, teeter or coning hinges, blad grips, pitch and scissor links, and control rods

6

The function of the flybar is

To decrease crosswind thrust on the blades and enhance flight stability by keeping the bar stable as the rotor spins

7

Many helicopters have a horizontal stabilizer located

On the tail boom

8

The purpose of the tail rotor is

To produce an anti-torque force acting perpendicular to the helicopter's longitudinal axis

9

Wheels on ____ types of helicopters are _____

some, retractable

10

A pilot controls a helicopter using

Pedals, a collective, throttle, and cyclic

11

From a physics perspective, the ____ force is deemed to act through a helicopter's _____

total weight, center of gravity

12

When a pilot banks a helicopter, causing it to turn, _________

The machine's weight increases

13

In the case of helicopters, lift is produced by _______ moving through the air at a speed sufficient to create ________

airfoils, a pressure differential

14

Thrust acts ____ to the aircraft's ____

parallel, longitudinal axis

15

Profile drag consists of _____ created by ______ and ______

skin friction, surface imperfections, form drag

16

Vortices produced by spinning rotor blades create

Induced drag

17

When plotted on a graph, L/DMAX is the point where the helicopter's

Total lift-to-drag ratio is the greatest

18

A helicopter's potential energy is affected by

The aircraft's height above the ground

19

Which of the following factors affect the lift produced by spinning rotor blades?

Airfoil coefficient of lift, air density, and blade area

20

What happens when a helicopter's main rotor blades spin rapidly?

The upper and lower sides of each blade experience a difference in pressure

21

Newton's Third Law of Motion applies to helicopters because

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

22

When the pilot pushes the cyclic forward

The main rotor disk tilts forward

23

Multi-engine helicopters have

a throttle lever for each engine

24

When the pilot wants the helicopter's nose to move left or right, he

Pushes on the corresponding pedal

25

For helicopters with a main rotor disk that spins counter-clockwise, the ___ airflow speed happens when each blade reaches the ___ position

maximum, three o'clock (right)

26

On the advancing rotor blade, lift ___ and the blade _____

increases, moves upward

27

The angle between the ____ of a rotor blade and its direction of motion relative to the _____ is the angle of attack (AOA), which is _____ angle

Chord line, air, an aerodynamic

28

The angle of incidence is between the ____ line of each blade and the rotor system's ____

chord, plane of rotation

29

When a helicopter engine ____, a clutch mechanism called a __________________

fails, free wheeling unit automatically disconnects the engine from the main rotor, allowing it to spin freely

30

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

upward flowing, outboard, retreating

31

Where there is too much lift, the main rotor blades will

Flap

32

Centrifugal force _____ spinning helicopter main rotor blades _______.

pulls, outward

33

If left uncorrected, greater lift produced by the advancing side of the rotor disk compared to the lift created by the disk's retreating side could make the helicopter ______.

uncontrollable

34

The driven region is _____ the blade tips and normally ____ percent of the radius.

nearest, 30

35

The _____ region is normally between a blade's _____ and _____ regions.

driving, stall, driven

36

Because of gyroscopic precession, if a wind gust applies a downward force on the left side of a helicopter's main rotor disk as it spins clockwise (as viewed from above), the movement response occurs at the __ o'clock position.

12

37

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

16, 24

38

Maximum ground effect occurs during a hover up to a heigh equal to __ percent of the main rotor's diameter

100

39

A pilot can worsen a helicopter's pendular action by

Over-controlling the aircraft

40

The phenomenon of a helicopter sinking into its own downwash is called

Settling with power