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55 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What kind of blades does a fully articulated rotor system have? |
Blades that can move independently |
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What is a semi rigid rotor system ? |
No vertical swag hinges and no teetering hinge,2 blades |
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In a rigid rotor system |
No Vertical OR horizontal hinges and blades can’t flap or drag |
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What are blade flextures normally fabricated from? |
Composite materials |
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What are the pros of blade flextures |
Low maintenance and require no lubrication , last longer |
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A majority of helicopters feature blades with what airfoil ? |
A symmetrical airfoil where the l center of pressure doesn’t change with angle of attack |
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What force do helicopters create |
Centrifugal force |
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What is the gyroscopic precision principle ? |
When a force is applied to the spinning gyro, the maximum reaction occurs 90 degrees in the direction of rotation |
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What is cyclic control |
Changes the pitch and angle of attack |
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For a helicopter to hover , lift and thrust from the…. |
Rotor system , act straight up and equal weight and drag acts straight down |
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What rotor system is subjected to Corolla effect |
2 blade rotor system |
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What changes as power changes ? |
Torque changes |
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The rotor’s rotation results in torque that |
Attempts to turn the fuselage in the opposite direction of blade rotation |
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What can counteract torque ? |
Anti torque tail rotor , NOTAR system , counter rotating main rotor system |
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What is translating tendency ? |
When helicopter drifts |
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How is translating tendency corrected ? |
Angular deflection of the rotor tip path |
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What is density altitude |
Standard air that is equal to the existing pressure altitude |
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Performance of both the engine and the rotor system depends on the.. |
Density altitude |
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The maximum speed of a helicopter is limited by what |
Retreating blade stall , caused by high angle attack and low win speeds |
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A helicopter encounters ground effect when hovering |
Less then 1 rotor diameter above the surface |
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What does an excessive angle of attack create |
Stalling |
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As the forward speed of a helicopter increases, the velocity of the air over the retreating blade |
Decreases and the angle of attract increases |
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Translational lift usually occurs at what air speed ? |
16-24 KIAS when the helicopter accelerates through its downwash and vortices into undisturbed air |
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Does translational lift effect horizontal or vertical flow |
Horizontal flow |
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During autorotation what direction is the wind moving through the main rotorbl |
Downward |
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In a modern main rotor system , the dual awash plates |
Transmit inputs from the cyclic and collective to the main rotor blades |
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What does the collective do |
Changes the pitch of all main rotor blades at the same time |
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The cyclic does what 3 things ? |
1 controls main rotor blades 2. Changes position if stationary swash plate 3. Tilts rotor disc |
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A four axis autopilot controls : |
Pitch, roll, anti torque and collective |
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Because of gyroscopic precision, mechanical linkages for the cyclic are rigged to |
Decrease pitch angle of the rotor blade 90 degrees before it reaches the direction of cyclic displacement |
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What is the purpose of synchronized elevators |
Teaxger |
Teacher |
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To relieve control forces and reduce pilot workload , turbine engine powered helicopters use : |
Hydraulically operated servos connected to the cyclic and collective controls |
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What doeS NOTAR stand for ? |
No tail rotor system |
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What does fenestron mean ? |
Fan in tail design |
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What is a debate on anti torque system? |
1.It reduces the chance of tail rotor impact with people or objects 2.contains blade in a shrouded duct |
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What is the ELEMENTARY and SIMPLISTIC method of providing stability to a main rotor system |
Offset the flapping hinge |
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The advantages of stability augmentation and autopilot systems are to: |
Reduce pilot work load Improve cover and flight performance and automatically navigate and perform instrument approaches |
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What are the two types of frequencies effecting helicopters |
High and low |
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Which vibration is felt by the pilot as a buzz in the airframe |
High frequency |
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What frequency is felt by the pilot as a beat or thump ? |
Low frequency |
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True or false both main rotor and tail’s rotors are usually balanced wh statically and dynamically |
True |
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Before a main rotor blade is mounted , it must be balanced |
Along the span and chord |
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Modern blade tracking systems include what |
Infrared light and strobe light held by a technician |
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On the ground a track of a blade can be changed by |
Teacher |
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For helicopters the greatest advantage of a turbine engine over a piston engine is its |
Power to weight ratio |
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True or false in a piston powered helicopter , the collective controls engine RPM not rotor rpm |
True |
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For helicopters applications , turboshaft engines used in modern helicopters |
Free turbine and have a direct shaft |
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Power from a turboshaftbebgine is displayed to the pilot by a |
Torque meter and dual needle tachometer |
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In a turbo shaft engine |
N1 indicated compressor and N2 is power turbine RPM |
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What is the tail rotor of a helicopter driven byv |
Transmission |
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What is a chip detector |
It detects metalic chips in the engine and metallic chips in the oil |
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When an engine fails in a helicopter |
The tail rotor continues to operate because it’s driven by the transmission not the engine |
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If a turbo shaft engine fails in flight what component disengages the transmission from the engine do the main rotor blades can contour rotating |
Freewheeling unit |
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To be certified , a helicopter must demonstrate |
The ability to autorotate safely to a landing |
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When viewed from above in a hover , a helicopter with a main rotor that turns CCW will produce |
Tail rotor thrust to the left moving the aircraft tail to the right and nose to the left |
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