SIFT Army Aviation Information Practice
Test-Graded A
What part decrease crosswind thrust on the blades and enhance flight stability by
keeping the bar stable as the rotor spins - ANSWER-The flybar
Helicopter turbine engines produce ___________ thrust per pound than piston engines
- ANSWER-More
The four main forces working on a helicopter are - ANSWER-Lift, weight, thrust, drag
Helicopters typically have between ___ and ___ main rotor blades - ANSWER-2 and 6
Many helicopters have a horizontal stabilizer located _____ - ANSWER-On the tail
boom
To produce an anti-torque force acting perpendicular to the helicopter's longitudinal
axis. - ANSWER-tail rotor
From a physics perspective, the _____ force is deemed to act through a helicopter's
_____ - ANSWER-Total weight, center of gravity
When a pilot banks a helicopter, causing it to turn, _____ - ANSWER-The machine's
weight increases
In the case of helicopters, lift is produced by _____ moving through the air at a speed
sufficient to create ______ - ANSWER-Airfoils, a pressure differential
Thrust acts _____ to the aircraft's _____ - ANSWER-Parallel, longitudinal axis
Vortices produced by spinning rotor blades create - ANSWER-Induced drag
defined as the sum of form drag(Shape of the object) and skin friction(imperfections) -
ANSWER-Profile drag
When plotted on a graph, L/DMAX is the point where the helicopter's _____ - ANSWER-
Total lift-to-drag ratio is the greatest
A helicopter's potential energy is affected by - ANSWER-The aircraft's height above the
ground
, 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
_____ - ANSWER-Uncontrollable
The driven region is _____ the blade tips and normally _____ percent of the radius -
ANSWER-Nearest, 30
The _____ region is normally between a blade's _____ and _____ regions - ANSWER-
Driving, stall, driven
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 - ANSWER-12
Helicopter's experience effective translational lift while transitioning to forward flight at
approximately _____ to _____ knots - ANSWER-16, 24
Maximum ground effect occurs during a hover up to a height equal to _____ percent of
the main rotor's diameter - ANSWER-100
A pilot can worsen a helicopter's pendular action by - ANSWER-Over-controlling the
aircraft
The phenomenon of a helicopter sinking into its own downwash is called - ANSWER-
Settling with power
Which of the following types of drag increase with an airspeed increase - ANSWER-
Parasitic and Profile
Which of the following decreases upon an increase to the collective pitch controller -
ANSWER-RPM
If the cyclic pitch control is pushed to the left, which way will the rotor disk tip and which
way will the helicopter move? - ANSWER-Left left
What is the danger of overloading a helicopter? - ANSWER-Decreased performance
and structural damage
Which of the following is a complication unique to sideward hovering flight as opposed
to forward and rearward flight - ANSWER-additional pressure needed on the anti-torque
pedals to deal with the weathervane
When performing an air taxi, which of the following should be avoided?
1. Flying in the shaded area of the height-velocity diagram
2. Flying over other aircraft, vehicles and personnel
Test-Graded A
What part decrease crosswind thrust on the blades and enhance flight stability by
keeping the bar stable as the rotor spins - ANSWER-The flybar
Helicopter turbine engines produce ___________ thrust per pound than piston engines
- ANSWER-More
The four main forces working on a helicopter are - ANSWER-Lift, weight, thrust, drag
Helicopters typically have between ___ and ___ main rotor blades - ANSWER-2 and 6
Many helicopters have a horizontal stabilizer located _____ - ANSWER-On the tail
boom
To produce an anti-torque force acting perpendicular to the helicopter's longitudinal
axis. - ANSWER-tail rotor
From a physics perspective, the _____ force is deemed to act through a helicopter's
_____ - ANSWER-Total weight, center of gravity
When a pilot banks a helicopter, causing it to turn, _____ - ANSWER-The machine's
weight increases
In the case of helicopters, lift is produced by _____ moving through the air at a speed
sufficient to create ______ - ANSWER-Airfoils, a pressure differential
Thrust acts _____ to the aircraft's _____ - ANSWER-Parallel, longitudinal axis
Vortices produced by spinning rotor blades create - ANSWER-Induced drag
defined as the sum of form drag(Shape of the object) and skin friction(imperfections) -
ANSWER-Profile drag
When plotted on a graph, L/DMAX is the point where the helicopter's _____ - ANSWER-
Total lift-to-drag ratio is the greatest
A helicopter's potential energy is affected by - ANSWER-The aircraft's height above the
ground
, 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
_____ - ANSWER-Uncontrollable
The driven region is _____ the blade tips and normally _____ percent of the radius -
ANSWER-Nearest, 30
The _____ region is normally between a blade's _____ and _____ regions - ANSWER-
Driving, stall, driven
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 - ANSWER-12
Helicopter's experience effective translational lift while transitioning to forward flight at
approximately _____ to _____ knots - ANSWER-16, 24
Maximum ground effect occurs during a hover up to a height equal to _____ percent of
the main rotor's diameter - ANSWER-100
A pilot can worsen a helicopter's pendular action by - ANSWER-Over-controlling the
aircraft
The phenomenon of a helicopter sinking into its own downwash is called - ANSWER-
Settling with power
Which of the following types of drag increase with an airspeed increase - ANSWER-
Parasitic and Profile
Which of the following decreases upon an increase to the collective pitch controller -
ANSWER-RPM
If the cyclic pitch control is pushed to the left, which way will the rotor disk tip and which
way will the helicopter move? - ANSWER-Left left
What is the danger of overloading a helicopter? - ANSWER-Decreased performance
and structural damage
Which of the following is a complication unique to sideward hovering flight as opposed
to forward and rearward flight - ANSWER-additional pressure needed on the anti-torque
pedals to deal with the weathervane
When performing an air taxi, which of the following should be avoided?
1. Flying in the shaded area of the height-velocity diagram
2. Flying over other aircraft, vehicles and personnel
