WorksheetsHelicopters Fundamentals
Total questions: 51
Worksheet time: 26mins
Fill in the blank: An ______ is any surface designed to produce lift.
airfoil
rudder
fuselage
aileron
The ______ is an imaginary straight line from the leading edge to the trailing edge of the airfoil.
chord line
camber line
span
thrust line
Fill in the blank: ______ is the direction of airflow with respect to an airfoil.
Relative wind
Chord line
Angle of attack
Lift vector
The ______ is the angle between the chord line and the relative wind.
angle of attack
angle of incidence
dihedral angle
yaw angle
The ______ is the acute angle between the blade chord line and a reference plane determined by the main rotor hub.
pitch angle
angle of attack
feathering angle
drag angle
The ______ is the plane of rotation of the rotor, created by the rotor blade tips while in rotation.
tip path plane
rotor hub
swashplate
collective pitch
The ______ is the tendency of a mass to increase or decrease its angular velocity when its radius of rotation is shortened or lengthened, respectively.
Coriolis effect
Doppler effect
Bernoulli's principle
Conservation of energy
______ use a pusher engine to create forward thrust and a non powered rotor driven by windmill action to provide lift.
Autogyros
Helicopters
Gliders
Blimps
Which of the following statements is TRUE about helicopter flight?
The tip path plane is always vertical.
Lift and thrust act straight up and are equal to gravity in hovering flight.
Thrust is always less than gravity in vertical flight.
The tail rotor is not needed for directional control.
In vertical flight, what is the relationship between thrust and gravity?
Thrust is less than gravity
Thrust is equal to gravity
Thrust is greater than gravity
Thrust is unrelated to gravity
What is the function of the auxiliary (tail) rotor on helicopters with single main rotor systems?
To increase lift
To compensate for torque and/or maintain directional control
To reduce drag
To provide forward thrust
What is the function of the transmission in a helicopter?
The transmission directs engine power to the main and tail rotor. Rotors must turn at a lower speed than engines and this is accomplished by reduction gears in the transmission.
The transmission controls the helicopter's altitude by adjusting the pitch of the blades.
The transmission is responsible for fueling the helicopter's engine during flight.
The transmission provides navigation data to the pilot through the instrument panel.
What are the two primary elements of the swash plate in a helicopter?
The stationary star and the rotating star.
The main rotor and the tail rotor.
The cyclic and the collective.
The fuselage and the landing gear.
Tension is defined as:
A force which tends to pull an object apart.
Resistance to any external force that tends to push an object together.
Combination of tension and compression acting at the same time in a twisting force.
A force that tends to pull a component apart on a smaller scale.
Compression is resistance to any external force that tends to push an object together.
True
False
Torsion is a combination of tension and ______ acting on the object at the same time in a twisting force.
compression
shear
bending
expansion
Bending is another combination of tension and compression, but acting on different areas that cause a _______.
distortion
rotation
expansion
fracture
Shear is a force that tends to pull a component apart. Similar to tension, but on a ______ scale.
smaller
larger
equal
atomic
Vibration is defined as:
A force which tends to pull an object apart.
Shaking rhythms in an up and down or side to side movement.
Resistance to any external force that tends to push an object together.
Combination of tension and compression acting at the same time in a twisting force.'
The angle of incidence is the acute angle between the rotor blade chord and a reference line on the blade attach point at a specific station.
True
False
The plane of rotation is at a right angle to the axis of rotation.
True
False
What is the axis of rotation in a helicopter?
The axis of rotation is the imaginary line about which the rotor rotates. It is represented by a line drawn through the center of and perpendicular to the tip path plane.
It is the path traced by the rotor blades as they move through the air.
It is the direction in which the helicopter moves forward.
It is the line connecting the tail rotor to the main rotor.
How is disc area calculated?
Disc area is calculated as a circle with its center at the hub axis and a radius of one blade length (disk radius squared and multiplied by 3.14).
Disc area is calculated by multiplying the blade length by the number of blades.
Disc area is calculated as the sum of the blade lengths divided by the hub diameter.
Disc area is calculated by measuring the circumference of the disc and multiplying by the blade width.
Disc loading is the ratio of helicopter gross weight to rotor disc area.
True
False
What is the difference between symmetry and dissymmetry of lift in helicopter flight?
Symmetry of lift means lift created by the rotor blades at all corresponding positions around the rotor disc are equal. Dissymmetry of lift is the unequal lift across the rotor disc resulting from the difference in the velocity of air over the advancing blade half and retreating blade half of the rotor disc area.
Symmetry of lift refers to the helicopter's ability to hover, while dissymmetry of lift only occurs during forward flight.
Symmetry of lift is when all rotor blades move at the same speed, and dissymmetry of lift is when some blades stop moving.
Symmetry of lift means the helicopter can fly upside down, while dissymmetry of lift prevents this.
Torque is the twisting moment created by the rotation of the main rotor head.
True
False
Which control changes the pitch angle of the rotor blades in a helicopter?
The collective control changes the pitch angle of the rotor blades.
The cyclic control changes the pitch angle of the rotor blades.
The throttle control changes the pitch angle of the rotor blades.
The rudder pedals change the pitch angle of the rotor blades.
The cyclic stick controls which axes of the helicopter?
The cyclic stick controls the longitudinal axis (roll) and lateral axis (pitch).
The cyclic stick controls only the vertical axis (yaw).
The cyclic stick controls the collective pitch only.
The cyclic stick controls the tail rotor only.
Antitorque pedals vary the pitch of the tail rotor blades and allow the pilot to maintain ________ control of the helicopter during hover and compensate for the torque of the main rotor head.
directional
vertical
rotational
altitude
What is the purpose of the rotor clutch in a helicopter?
To disconnect the rotor from the engine to relieve the starter load and allow the engine to be started and gradually assume the load of driving the rotor system.
To increase the speed of the helicopter during flight.
To control the direction of the helicopter's tail rotor.
To provide power to the helicopter's landing gear system.
The freewheeling unit provides for ________ capabilities by automatically disconnecting the rotor system from the engine when the engine stops or slows below the equivalent of rotor RPM.
autorotative
combustive
inertial
magnetic
In forward horizontal flight, the angle of attack of the ________ blade is greater than the retreating blade.
advancing
leading
trailing
main
Coning is the tendency of the rotor blades to flex ________ when lift forces are applied to them.
upward
downward
sideways
inward
Blade flap is the up and down movement of rotor blades positioned at right angles to the plane of ________.
rotation
symmetry
lift
drag
True or False: The feathering axis is responsible for the up and down movement of rotor blades.
True
False
What is the feathering axis in a helicopter rotor blade?
The feathering axis is the axis about which the pitch angle of a rotor blade is varied. Sometimes referred to as the spanwise axis.
The feathering axis is the axis about which the rotor blade rotates to generate lift.
The feathering axis is the axis along which the rotor blade is attached to the helicopter hub.
The feathering axis is the axis about which the helicopter fuselage rotates.
Hovering is a maneuver in which the helicopter is maintained in nearly ________ flight.
motionless
vertical
horizontal
rotational
What is ground effect in helicopter flight?
Ground effect occurs when a helicopter is operated near the surface, usually at less than one rotor diameter above the surface, resulting in increased lift at lower power requirement to support a given weight.
Ground effect is the phenomenon where a helicopter loses all lift when flying above water.
Ground effect refers to the increased drag experienced by a helicopter at high altitudes.
Ground effect is the sudden loss of engine power when a helicopter is operated near mountains.
Ground resonance is a dangerous condition that can cause structural failure in helicopters if not corrected immediately.
True
False
Blade tracking is used to determine the ________ position of the blades during rotation.
relative
absolute
vertical
horizontal
Which of the following is NOT a main rotor tracking method?
Flag tracking
Electro-optical tracking
Magnetic resonance tracking
Strobe light tracking
Describe the flag tracking method for main rotor tracking.
Flag tracking is the earliest technique in which blade tips were marked with colored chalk. A white strip of cloth is mounted to a pole and pushed to the edge of the blade path. Marks on the cloth gave a measure of blade path.
Flag tracking uses laser sensors to detect the position of each blade as it passes a fixed point.
Flag tracking involves attaching electronic transducers to each blade to record vibration patterns.
Flag tracking is performed by using a strobe light to visually freeze the motion of the blades and compare their positions.
What is the purpose of using vibration sensors in rotor tracking?
Sensors were attached to the airframe to track vibrations and help determine problems with the rotor.
To increase the speed of the rotor automatically.
To lubricate the rotor blades during operation.
To provide power to the rotor system.
What is static bubble balancing? Static bubble balancing involves balancing rotors on the center point and ________ to one side to balance the assembly.
adding weight
removing air
rotating faster
changing color
What does weighing blades involve? Weighing blades involves weighing individual blades and installing equal blades ________ degrees out from each other.
180
90
120
45
What are nomograms used for in rotor balancing? Nomograms are chart readings created from using a ________ to determine the phase of vibration in combination with a meter to find the amplitude of the vibration and determine where and how much weight to use.
strobe light
tachometer
oscilloscope
thermometer
Which rotor smoothing method uses procedures to be followed in a particular order based on the interaction between blade imbalance and blade track at hover?
Algorithms
Random Sampling
Visual Inspection
Trial and Error
Which rotor smoothing method uses computers to analyze data from multiple flights to form the procedures to make the required adjustments?
Computer based algorithms
Manual balancing
Visual inspection
Trial and error
Which rotor smoothing method is based on data from a single flight and only works when the aircraft is close enough to normal conditions?
Unreliable algorithm
Kalman filter method
Multiple flight averaging
Fourier transform smoothing
Which rotor smoothing method uses the single flight method, but only makes one adjustment and then verifies the change at the next flight, working on the theory of averages?
Improved fault tolerant algorithms
Continuous tracking method
Dual adjustment method
Iterative balancing technique
What are wing vortices
Air slipping from the higher pressure below wing to the lower pressure above wing creates a swirling trail behind aircraft
