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Questions and Answers
What happens to a helicopter when lift exceeds weight?
What happens to a helicopter when lift exceeds weight?
In sideward flight, how is the total lift-thrust vector oriented?
In sideward flight, how is the total lift-thrust vector oriented?
What compensates for torque reaction and provides directional control in helicopters?
What compensates for torque reaction and provides directional control in helicopters?
During autorotation, how does engine power affect the main rotor?
During autorotation, how does engine power affect the main rotor?
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Which of the following designs may not face a torque issue?
Which of the following designs may not face a torque issue?
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What occurs when drag exceeds thrust in a helicopter?
What occurs when drag exceeds thrust in a helicopter?
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What is the purpose of foot pedals in the flight deck?
What is the purpose of foot pedals in the flight deck?
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What is the role of the tail rotor in a single main rotor helicopter?
What is the role of the tail rotor in a single main rotor helicopter?
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What is the blade tip speed of the helicopter?
What is the blade tip speed of the helicopter?
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At what speed should pilots avoid exceeding to prevent retreating blade stall?
At what speed should pilots avoid exceeding to prevent retreating blade stall?
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What effect does the difference in speed between the advancing and retreating sides of the rotor blades create?
What effect does the difference in speed between the advancing and retreating sides of the rotor blades create?
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In a helicopter with counterclockwise blade rotation, what is the usual rolling tendency?
In a helicopter with counterclockwise blade rotation, what is the usual rolling tendency?
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What type of hinge allows individual rotor blades to flap up and down as they rotate?
What type of hinge allows individual rotor blades to flap up and down as they rotate?
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In a semirigid rotor system, how do the blades interact during flapping?
In a semirigid rotor system, how do the blades interact during flapping?
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What is the first step in rigging the flight control systems?
What is the first step in rigging the flight control systems?
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What is a common symptom of retreating blade stall?
What is a common symptom of retreating blade stall?
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Which tool is NOT mentioned for checking the angular difference during rigging?
Which tool is NOT mentioned for checking the angular difference during rigging?
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What is indicated on a placard and marked on the airspeed indicator by a red line?
What is indicated on a placard and marked on the airspeed indicator by a red line?
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What should be verified after completing the static rigging?
What should be verified after completing the static rigging?
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Which of the following is necessary for the correct tracking of rotor blades?
Which of the following is necessary for the correct tracking of rotor blades?
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What is the purpose of setting the maximum range of travel for components?
What is the purpose of setting the maximum range of travel for components?
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What must be checked regarding the attachments after rigging is complete?
What must be checked regarding the attachments after rigging is complete?
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Which aspect is NOT part of the adjustments for blade angles in rotor systems?
Which aspect is NOT part of the adjustments for blade angles in rotor systems?
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When tabs are provided on the main rotor blades, what must be ensured?
When tabs are provided on the main rotor blades, what must be ensured?
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What occurs to the advancing blade and retreating blade during upward and downward flapping?
What occurs to the advancing blade and retreating blade during upward and downward flapping?
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What is referred to as blowback in helicopter rotor dynamics?
What is referred to as blowback in helicopter rotor dynamics?
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How does the pilot manage blowback as forward speed increases?
How does the pilot manage blowback as forward speed increases?
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What effect does cyclic feathering have at low forward speeds?
What effect does cyclic feathering have at low forward speeds?
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What happens to the rotor disc when airspeed is gained and flapping is maximized?
What happens to the rotor disc when airspeed is gained and flapping is maximized?
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At a hover, what is the characteristic of the pitch angle on the rotor blades?
At a hover, what is the characteristic of the pitch angle on the rotor blades?
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What is the overall effect of cyclic feathering on the rotor system?
What is the overall effect of cyclic feathering on the rotor system?
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What aspect of rotor dynamics does the cyclic input primarily influence?
What aspect of rotor dynamics does the cyclic input primarily influence?
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What is the primary function of the stationary swash plate in a helicopter?
What is the primary function of the stationary swash plate in a helicopter?
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How does the rotating swash plate interact with the stationary swash plate?
How does the rotating swash plate interact with the stationary swash plate?
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What mechanism allows a helicopter's main rotor to continue turning during engine failure?
What mechanism allows a helicopter's main rotor to continue turning during engine failure?
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What is the purpose of the collective pitch control in a helicopter?
What is the purpose of the collective pitch control in a helicopter?
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Which statement best describes the role of antitorque pedals in helicopter operation?
Which statement best describes the role of antitorque pedals in helicopter operation?
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Where is the collective pitch control located in the helicopter?
Where is the collective pitch control located in the helicopter?
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What is a key feature of the freewheeling unit in a helicopter?
What is a key feature of the freewheeling unit in a helicopter?
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What allows both swash plates to tilt and slide together as a unit?
What allows both swash plates to tilt and slide together as a unit?
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Study Notes
Rotor Blade Rigging
- Rotor blade rigging is a critical process that involves adjusting the pitch angles, tracking, and clearances of the rotor blades.
- The rigging process includes checking the fore-and-aft, lateral cyclic pitch, and collective pitch blade angles.
- The tracking of the main rotor blades must be correct.
- In multirotor aircraft, the rigging and movement of the rotor blades must be synchronized.
- Tabs on main rotor blades must be correctly set.
- The neutral, maximum and minimum pitch angles and coning angles of the tail rotor blades must be correct.
- Dual controls, if provided, must function correctly and in synchronization.
- All attaching, securing, and pivot points should be properly secured after rigging.
- Bolts, nuts and rod ends should be properly secured and safetied as specified in the manufacturers’ maintenance and service instructions.
Flight Controls
- Lift, weight, thrust, and drag are opposing forces that affect the flight of a helicopter.
- In straight-and-level flight, the weight and thrust equals drag.
- If lift exceeds weight, the helicopter will climb; if lift is less than weight, the helicopter will descend.
- If thrust exceeds drag, the helicopter will increase speed; if thrust is less than drag, it will decrease speed.
- Sideward flight is achieved by tilting the tip-path plane sideward, tilting the lift-thrust vector in the direction of flight.
- Rearward flight is achieved by tilting the tip-path plane rearward, tilting the lift-thrust vector rearward.
- The Fenestron® tail rotor system is an alternative method for compensating for torque and providing directional control.
- The blade tip speed of the Fenestron® tail rotor system is around 300 knots.
Dissymmetry of Lift
- Dissymmetry of lift occurs because of the difference in relative windspeed on the advancing and retreating blades in forward flight.
- The advancing blade has a higher relative windspeed, which produces more lift, while the retreating blade has a lower relative windspeed, which produces less lift.
- The difference in lift between the advancing and retreating blades causes a rolling tendency, typically to the left in helicopters with counterclockwise blade rotation.
- Pilots can avoid retreating blade stall by not exceeding the never-exceed speed (VNE).
- Aerodynamic flapping of the rotor blades helps compensate for dissymmetry of lift.
- The advancing blade flaps upwards as it rotates, reducing lift, while the retreating blade flaps downwards, increasing lift.
Cyclic Feathering
- Cyclic feathering allows the pilot to control the direction of flight by changing the pitch angle of the rotor blades differentially around the rotor disc.
- In forward flight, the pilot must continually move the cyclic forward to counteract blowback.
- The stationary swash plate is mounted around the main rotor mast and is connected to the cyclic and collective controls by pushrods. It is restrained from rotating, but can tilt in all directions and move vertically.
- The rotating swash plate is mounted to the stationary swash plate and is connected to the mast by drive links. It rotates with the main rotor mast.
- Both swash plates tilt and slide up and down as one unit.
- The rotating swash plate is connected to the pitch horns by pitch links.
Helicopter Controls
- The three major controls in a helicopter are the collective pitch control, cyclic pitch control, and antitorque pedals or tail rotor control.
- The collective pitch control is located on the left side of the pilot’s seat and is operated with the left hand.
- The throttle control is mounted directly to the collective pitch control.
- The freewheeling unit allows the main rotor to continue turning even if the engine is not running, ensuring safe landing in case of engine failure.
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Description
This quiz covers the essential processes involved in rotor blade rigging, including pitch adjustments and sync movements in multirotor aircraft. Additionally, it explores the fundamental forces of lift, weight, thrust, and drag affecting helicopter flight. Test your knowledge on these critical aviation engineering concepts.
