Podcast
Questions and Answers
What is the name of the part if the helicopter identified by the number 1?
What is the name of the part if the helicopter identified by the number 1?
Tail rotor
What are the various forces acting on the helicopter in a hover and their direction?
What are the various forces acting on the helicopter in a hover and their direction?
Lift (upward), Weight (downward), Thrust (forward), and Drag (backward)
What are the various forces acting on the helicopter in a climb or accent and their direction?
What are the various forces acting on the helicopter in a climb or accent and their direction?
Lift (upward and greater than weight), Weight (downward), Thrust (forward), and Drag (backward)
What are the various forces acting on the helicopter in forward flight and their direction?
What are the various forces acting on the helicopter in forward flight and their direction?
What is the name of the angle between the relative wind vector and the chord line of the blade?
What is the name of the angle between the relative wind vector and the chord line of the blade?
What is the name of the tip path that is created if the blades are straight out from the mast, generating no lift?
What is the name of the tip path that is created if the blades are straight out from the mast, generating no lift?
What is the name of the number of degrees of rotation of the airfoil between the plane of rotation and the chord line of the blade?
What is the name of the number of degrees of rotation of the airfoil between the plane of rotation and the chord line of the blade?
What is the name of the axis on which the blade will rotate to change the angle of the chord line of the blade?
What is the name of the axis on which the blade will rotate to change the angle of the chord line of the blade?
Blades moving through the same point in space as they pass through the same point in the 360 degrees of rotation are said to be:
Blades moving through the same point in space as they pass through the same point in the 360 degrees of rotation are said to be:
Which Force acting on the main rotor blade tends to sent it straight out from the center of rotation as it turns?
Which Force acting on the main rotor blade tends to sent it straight out from the center of rotation as it turns?
What is the name of the upward flexing of the blades caused by a combination of lift and centrifugal forces?
What is the name of the upward flexing of the blades caused by a combination of lift and centrifugal forces?
Which of the following is a hazard to equipment and personnel caused by the main rotor system during start-up and shut down?
Which of the following is a hazard to equipment and personnel caused by the main rotor system during start-up and shut down?
When wanting to tilt the main rotor disk to the left on a rotor system rotating counter clockwise looking down from the top, where will the highest blade pitch angle be in the 360 degrees of rotation?
When wanting to tilt the main rotor disk to the left on a rotor system rotating counter clockwise looking down from the top, where will the highest blade pitch angle be in the 360 degrees of rotation?
When wanting to tilt the main rotor disk forward on a rotor system rotating counter clockwise looking down from the top, where will the highest blade pitch angle be in the 360 degrees of rotation?
When wanting to tilt the main rotor disk forward on a rotor system rotating counter clockwise looking down from the top, where will the highest blade pitch angle be in the 360 degrees of rotation?
Due to the flapping up and down of the blades during forward flight caused by dissymmetry of lift, when is the angle of attack of the blade the greatest?
Due to the flapping up and down of the blades during forward flight caused by dissymmetry of lift, when is the angle of attack of the blade the greatest?
What is a key factor in limiting the maximum forward speed of the helicopter?
What is a key factor in limiting the maximum forward speed of the helicopter?
What flight condition exists when the helicopter is in a hover less than one-half the diameter of the rotor system from the ground and lift generated is increased?
What flight condition exists when the helicopter is in a hover less than one-half the diameter of the rotor system from the ground and lift generated is increased?
What flight condition exists when the helicopter is moving forward at a speed of approximately 16 to 24 knots (15 to 20 mph) and lift generated is increased?
What flight condition exists when the helicopter is moving forward at a speed of approximately 16 to 24 knots (15 to 20 mph) and lift generated is increased?
What flight condition exists when the helicopter has landed and a self-excited vibration occurs that builds uncontrollably?
What flight condition exists when the helicopter has landed and a self-excited vibration occurs that builds uncontrollably?
Which stabilizing measure used in fixed wing stability is similar to the use of pre-coned blades as a stabilizing measure in rotary wing aircraft design?
Which stabilizing measure used in fixed wing stability is similar to the use of pre-coned blades as a stabilizing measure in rotary wing aircraft design?
Which stabilizing system used in rotary wing design employs the concept of rigidity in space of a rotating mass?
Which stabilizing system used in rotary wing design employs the concept of rigidity in space of a rotating mass?
Which stabilizing system used in rotary wing design employs the use of an autopilot system?
Which stabilizing system used in rotary wing design employs the use of an autopilot system?
What does the acronym “Nr” mean when discussing the concepts of Autorotation?
What does the acronym “Nr” mean when discussing the concepts of Autorotation?
What is the term "Deadman's Curve” relate to when discussing Autorotation?
What is the term "Deadman's Curve” relate to when discussing Autorotation?
What causes the blades to continue rotating during an autorotation?
What causes the blades to continue rotating during an autorotation?
The engine power being applied to drive the rotor system will cause what equal and opposite reaction?
The engine power being applied to drive the rotor system will cause what equal and opposite reaction?
What is the name of the system that counteracts the equal and opposite reaction of the engine driving the rotors that uses two main rotors counter rotating placed one in front of the other?
What is the name of the system that counteracts the equal and opposite reaction of the engine driving the rotors that uses two main rotors counter rotating placed one in front of the other?
What is the name of the system that counteracts the equal and opposite reaction of the engine driving the rotors that uses two main rotors counter rotating placed one beside the other?
What is the name of the system that counteracts the equal and opposite reaction of the engine driving the rotors that uses two main rotors counter rotating placed one beside the other?
What is the name of the system that counteracts the equal and opposite reaction of the engine driving the rotors that uses smaller rotor mounted vertically at the back of the helicopter?
What is the name of the system that counteracts the equal and opposite reaction of the engine driving the rotors that uses smaller rotor mounted vertically at the back of the helicopter?
With reference to the tail rotor system what is the meaning of the term "translating tendency"?
With reference to the tail rotor system what is the meaning of the term "translating tendency"?
What are the three axis of movement that every main rotor head and blade design needs to take into account?
What are the three axis of movement that every main rotor head and blade design needs to take into account?
What is the name of the Rotary Wing Concept that causes a difference in flight forces between the advancing and retreating blades in forward flight?
What is the name of the Rotary Wing Concept that causes a difference in flight forces between the advancing and retreating blades in forward flight?
What is the effect caused by the change in blade speed due to the blade center of gravity moving in when the blade flaps up?
What is the effect caused by the change in blade speed due to the blade center of gravity moving in when the blade flaps up?
What is the name of the Rotary Wing Concept caused by the unequal lift across a rotor disc that occurs in forward flight due to the difference in airflow over the advancing and retreating blades
What is the name of the Rotary Wing Concept caused by the unequal lift across a rotor disc that occurs in forward flight due to the difference in airflow over the advancing and retreating blades
What is the name of the Rotary Wing Concept that states a change in blade angle result in a resultant action 90 degrees later in the direction of rotation?
What is the name of the Rotary Wing Concept that states a change in blade angle result in a resultant action 90 degrees later in the direction of rotation?
Which Main Rotor Head design has only one axis of movement?
Which Main Rotor Head design has only one axis of movement?
Which type of Main Rotor Head design has three axis of rotation?
Which type of Main Rotor Head design has three axis of rotation?
Flashcards
What is part #7?
What is part #7?
The tail rotor controls the helicopter's yaw.
What are the forces in a hover?
What are the forces in a hover?
Lift, weight, thrust, and drag.
What is the Angle of Attack?
What is the Angle of Attack?
Induced flow causes the angle between the relative wind and the chord line.
What is blade coning?
What is blade coning?
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What is a rotor hazard?
What is a rotor hazard?
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Advancing vs Retreating blade lift
Advancing vs Retreating blade lift
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Change in blade angle?
Change in blade angle?
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Which rotor design has 3 axis?
Which rotor design has 3 axis?
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Study Notes
Helicopter Parts (refer to the image)
- Number 1 refers to the tail rotor
- Number 4 refers to the main rotor
- Number 3 refers to the rotor mast
- Number 2 refers to the cabin
Forces in a Hover
- Lift acts upwards
- Weight acts downwards
- Thrust and drag are minimal
Forces During Climb or Ascent
- Lift is greater than weight, acting upwards
- Thrust acts upwards and forwards, overcoming drag
- Weight acts downwards
Forces During Descent
- Weight is greater than lift, acting downwards
- Drag acts upwards, opposing the descent
- Thrust may be reduced or reversed
Forces in Forward Flight
- Lift acts upwards, opposing weight
- Thrust acts forwards, overcoming drag
- Drag acts rearwards, opposing thrust
- Weight acts downwards
Blade Angle Definitions
- The angle between the relative wind vector and the chord line of the blade is the angle of attack
Tip Path Plane
- A tip path that is created if the blades are straight out from the mast, generating no lift is a coning
Airfoil Rotation
- The number of degrees of rotation of the airfoil between the plane of rotation and the chord line of the blade is the angle of incidence, or pitch angle
Blade Rotation
- The axis on which the blade rotates to change the angle of the chord line of the blade is the feathering axis
Blade Position
- Blades moving through the same point in space as they pass through the same point in the 360 degrees of rotation are said to be tracking
Forces on Rotor Blades
- The force acting on the main rotor blade that tends to send it straight out from the center of rotation as it turns is centrifugal force
Blade Flexing
- The upward flexing of the blades caused by a combination of lift and centrifugal forces is called coning
Rotor Hazards
- A hazard to equipment and personnel caused by the main rotor system during start-up and shut down is rotor droop
Tilting the Rotor Disk
- Tilting the main rotor disk to the left on a counter-clockwise rotor system requires the highest blade pitch angle at the front
- When wanting to tilt the main rotor disk forward on a counter-clockwise rotor system requires highest blade pitch angle on the right.
- Tilting the main rotor disk to the back on a counter-clockwise rotor system requires the highest blade pitch angle on the left
- Tilting the main rotor disk to the right on a counter-clockwise rotor system requires the higest blade pitch angle at the back
Blade Angle of Attack
- Due to the flapping up and down of the blades during forward flight caused by dissymmetry of lift, the angle of attack of the blade is greatest when the blade is retreating
Helicopter Speed Limits
- A key factor in limiting the maximum forward speed of the helicopter is retreating blade stall
Flight Conditions
- When in a hover less than one-half the diameter of the rotor system from the ground and lift generated is increased, the flight condition is in ground effect (IGE)
- When moving forward at approximately 16 to 24 knots (15 to 20 mph) and lift generated is increased, the flight condition is effective translational lift (ETL)
- When the helicopter has landed and a self-excited vibration occurs that builds uncontrollably, the flight condition is ground resonance
Rotary Wing Design
- Stabilizing measure similar to pre-coned blades: Dihedral
- Stabilizing system employing rigidity in space: Gyroscopic Stabilizer
- Stabilizing system employing an autopilot: Electronic Stabilization
Autorotation
- Nr Means: Rotor RPM
- "Deadman's Curve" relates to: Height/Velocity Diagram
- Autorotation maintained by: Upward rushing air
Torque Reaction
- Engine power applied to the rotor system causes: Torque
- Dual main rotors counter-rotating, front to back: Tandem Rotors
- Dual main rotors counter-rotating, side by side: Transverse Rotors
- Dual main rotors counter-rotating, one above the other: Coaxial Rotors
- Smaller rotor mounted vertically at the tail: Tail Rotor
Translating Tendency
- Definition: Tendency to drift laterally
Rotor Head Design
- Three axes of movement: Pitch, Roll, and Yaw
- Rotary Wing Concept causing lift differences in forward flight: Dissymmetry of Lift
- Blade speed changes from flapping: Coriolis Effect
- Rotary Wing Concept from unequal lift across rotor: Translational Lift
- Rotary Wing Concept of blade angle action: Gyroscopic Precession
- One axis of movement: Teetering rotor head
- Three axis of movement: Fully articulated rotor head
- Two axis of movement: Rigid rotor head
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