Podcast
Questions and Answers
What is the purpose of the cyclic control in a helicopter?
What is the purpose of the cyclic control in a helicopter?
Which control increases or decreases the pitch on the main rotor blades?
Which control increases or decreases the pitch on the main rotor blades?
What is the primary function of anti-torque control in a helicopter?
What is the primary function of anti-torque control in a helicopter?
Which mechanism can boost flight controls in helicopters?
Which mechanism can boost flight controls in helicopters?
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Why are boosted flight controls important for helicopters?
Why are boosted flight controls important for helicopters?
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What component is directly controlled by the pilot to change rotor pitch in a boosted system?
What component is directly controlled by the pilot to change rotor pitch in a boosted system?
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What allows helicopters to return to unassisted control in case of a system failure?
What allows helicopters to return to unassisted control in case of a system failure?
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Which type of control allows the pilot to manage the attitude and direction of the helicopter?
Which type of control allows the pilot to manage the attitude and direction of the helicopter?
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What is the primary purpose of the cyclic control system?
What is the primary purpose of the cyclic control system?
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What happens when the cyclic control is moved forward?
What happens when the cyclic control is moved forward?
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How does the cyclic control affect rotor blade pitch during its movement?
How does the cyclic control affect rotor blade pitch during its movement?
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What is the role of the horizontal stabiliser in relation to the cyclic control?
What is the role of the horizontal stabiliser in relation to the cyclic control?
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What occurs due to gyroscopic precession in relation to the cyclic control?
What occurs due to gyroscopic precession in relation to the cyclic control?
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What effect does increasing the pitch of the rotor blades have?
What effect does increasing the pitch of the rotor blades have?
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Where is the collective pitch control typically located?
Where is the collective pitch control typically located?
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What does the collective pitch control change?
What does the collective pitch control change?
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What is one function of the droop compensation device in a helicopter?
What is one function of the droop compensation device in a helicopter?
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What happens when the collective pitch is lowered?
What happens when the collective pitch is lowered?
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What is the relationship between the cyclic control and the direction of helicopter movement?
What is the relationship between the cyclic control and the direction of helicopter movement?
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Which mechanism is used to allow for adjustments in engine power related to changes in collective pitch?
Which mechanism is used to allow for adjustments in engine power related to changes in collective pitch?
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What does a higher drag result from when increasing rotor blade pitch?
What does a higher drag result from when increasing rotor blade pitch?
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What is NOT a function of the cyclic control?
What is NOT a function of the cyclic control?
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What is the primary requirement during rigging procedures for helicopters?
What is the primary requirement during rigging procedures for helicopters?
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Which tool is NOT typically required for helicopter rigging procedures?
Which tool is NOT typically required for helicopter rigging procedures?
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What should be observed when making minor adjustments after initial rigging?
What should be observed when making minor adjustments after initial rigging?
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What position should the cyclic control be in during rigging?
What position should the cyclic control be in during rigging?
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Which of the following is typically checked during the rigging procedure?
Which of the following is typically checked during the rigging procedure?
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What is the purpose of using rigging jigs and pins?
What is the purpose of using rigging jigs and pins?
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What should be used to determine predetermined degrees in components during rigging?
What should be used to determine predetermined degrees in components during rigging?
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What is typically the last step when rigging a cyclic system?
What is typically the last step when rigging a cyclic system?
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What mathematical tool is used to measure degrees during rigging?
What mathematical tool is used to measure degrees during rigging?
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Which statement about helicopter rigging adjustments is false?
Which statement about helicopter rigging adjustments is false?
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What is the primary function of the tail rotor in a helicopter?
What is the primary function of the tail rotor in a helicopter?
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What is translating tendency in helicopters?
What is translating tendency in helicopters?
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How is directional control achieved in single main rotor helicopters?
How is directional control achieved in single main rotor helicopters?
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What does the anti-torque rotor help the helicopter maintain during flight?
What does the anti-torque rotor help the helicopter maintain during flight?
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What type of control mechanism do many designs use to correct tail rotor drift?
What type of control mechanism do many designs use to correct tail rotor drift?
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Which of the following is a disadvantage of single rotor designs?
Which of the following is a disadvantage of single rotor designs?
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What unique feature does the NOTAR system provide?
What unique feature does the NOTAR system provide?
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Which component helps change the pitch of the tail rotor blades?
Which component helps change the pitch of the tail rotor blades?
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What effect does increasing the distance of the tail rotor from the mast have?
What effect does increasing the distance of the tail rotor from the mast have?
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What is a common feature of the Fenestron tail rotor?
What is a common feature of the Fenestron tail rotor?
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What is the significance of the tail rotor thrust direction in relation to the main rotor torque?
What is the significance of the tail rotor thrust direction in relation to the main rotor torque?
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Which component of the helicopter provides a high volume of low-pressure air in the NOTAR system?
Which component of the helicopter provides a high volume of low-pressure air in the NOTAR system?
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What is the purpose of the horizontal component of total rotor thrust after correcting translating tendency?
What is the purpose of the horizontal component of total rotor thrust after correcting translating tendency?
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What allows the tail rotor hub to function effectively in changing the pitch of the blades?
What allows the tail rotor hub to function effectively in changing the pitch of the blades?
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What can the throttle be used for during a tail rotor failure?
What can the throttle be used for during a tail rotor failure?
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What happens when the throttle is rolled from 'off' to 'idle'?
What happens when the throttle is rolled from 'off' to 'idle'?
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How does a correlating unit function in a piston engine helicopter?
How does a correlating unit function in a piston engine helicopter?
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What is the purpose of the RPM adjustment button?
What is the purpose of the RPM adjustment button?
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What is the significance of the push-pull tubes in a collective system?
What is the significance of the push-pull tubes in a collective system?
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Why should torque tubes be inspected periodically?
Why should torque tubes be inspected periodically?
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What is the main function of bellcranks in a helicopter collective system?
What is the main function of bellcranks in a helicopter collective system?
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What is the primary purpose of a mixer box in a helicopter?
What is the primary purpose of a mixer box in a helicopter?
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What occurs when a collective lever is pulled up in a gas turbine helicopter?
What occurs when a collective lever is pulled up in a gas turbine helicopter?
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What material are bellcranks usually constructed from?
What material are bellcranks usually constructed from?
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How does a gradient unit function in helicopter control systems?
How does a gradient unit function in helicopter control systems?
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Which component helps maintain rotor RPM when the collective control is adjusted?
Which component helps maintain rotor RPM when the collective control is adjusted?
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What happens when a pilot raises the collective lever in a helicopter?
What happens when a pilot raises the collective lever in a helicopter?
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What role do anti-torque pedals play in helicopter operation?
What role do anti-torque pedals play in helicopter operation?
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What advantage does the linear actuator provide in Bell helicopters?
What advantage does the linear actuator provide in Bell helicopters?
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What can happen due to wear factors in push-pull tubes?
What can happen due to wear factors in push-pull tubes?
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Which component is responsible for transferring pilot inputs to the rotor blades?
Which component is responsible for transferring pilot inputs to the rotor blades?
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What is the purpose of the mixer box in a helicopter's flight control system?
What is the purpose of the mixer box in a helicopter's flight control system?
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What mechanism assists in trimming a helicopter's flight attitude?
What mechanism assists in trimming a helicopter's flight attitude?
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What is the effect of moving the cyclic control in a helicopter?
What is the effect of moving the cyclic control in a helicopter?
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What role does the starter button play in helicopter operations?
What role does the starter button play in helicopter operations?
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Which position activates both the forward and downward angled landing lights?
Which position activates both the forward and downward angled landing lights?
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What determines the required positive pitch for the tail rotor during takeoff?
What determines the required positive pitch for the tail rotor during takeoff?
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How does the attachment of a pitch horn affect blade angle movement?
How does the attachment of a pitch horn affect blade angle movement?
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During cruising, where should the anti-torque pedals be positioned?
During cruising, where should the anti-torque pedals be positioned?
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What occurs if there is no mixer device installed in a helicopter?
What occurs if there is no mixer device installed in a helicopter?
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Why is trimming necessary for helicopters during flight?
Why is trimming necessary for helicopters during flight?
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What should the collective lever movement result in for blade angles?
What should the collective lever movement result in for blade angles?
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What is a potential consequence of using a hydraulic boost in helicopter controls?
What is a potential consequence of using a hydraulic boost in helicopter controls?
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What is the primary advantage of a shrouded tail rotor design, known as a Fenestron?
What is the primary advantage of a shrouded tail rotor design, known as a Fenestron?
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How does a canted tail rotor contribute to the helicopter's performance?
How does a canted tail rotor contribute to the helicopter's performance?
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What is the purpose of using dual rotors in helicopters?
What is the purpose of using dual rotors in helicopters?
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What configuration do tandem rotor helicopters use?
What configuration do tandem rotor helicopters use?
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What distinguishes intermeshing rotor designs?
What distinguishes intermeshing rotor designs?
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What is a characteristic of boosted flight control systems in helicopters?
What is a characteristic of boosted flight control systems in helicopters?
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Which component in boosted flight controls helps maintain system pressure?
Which component in boosted flight controls helps maintain system pressure?
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Why are hydraulic pumps crucial in boosted flight controls?
Why are hydraulic pumps crucial in boosted flight controls?
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What is the role of servo actuators in flight control systems?
What is the role of servo actuators in flight control systems?
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In a fly-by-wire system, what replaces the conventional mechanical linkages?
In a fly-by-wire system, what replaces the conventional mechanical linkages?
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What can be said about the performance of a Fenestron compared to conventional tail rotors?
What can be said about the performance of a Fenestron compared to conventional tail rotors?
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What characterizes contra-rotating rotor systems?
What characterizes contra-rotating rotor systems?
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What is a disadvantage of using shrouded tail rotors like the Fenestron?
What is a disadvantage of using shrouded tail rotors like the Fenestron?
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Which of the following would NOT be a component typically found in a hydraulic flight control system?
Which of the following would NOT be a component typically found in a hydraulic flight control system?
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What is the function of electrical transducers in a fly-by-wire system?
What is the function of electrical transducers in a fly-by-wire system?
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What does bias control do in helicopter trimming?
What does bias control do in helicopter trimming?
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What is the primary purpose of horizontal stabilisers on a helicopter?
What is the primary purpose of horizontal stabilisers on a helicopter?
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Why can stabilisers be detrimental during rearward flight?
Why can stabilisers be detrimental during rearward flight?
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What defines synch elevators in helicopter design?
What defines synch elevators in helicopter design?
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What is the main function of stabilators on a helicopter?
What is the main function of stabilators on a helicopter?
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How are tail rotor blades usually balanced during manufacturing?
How are tail rotor blades usually balanced during manufacturing?
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What does static balancing of blades require?
What does static balancing of blades require?
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What is the significance of control rigging after replacing helicopter components?
What is the significance of control rigging after replacing helicopter components?
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What is commonly a risk when adding weight to rotor blades?
What is commonly a risk when adding weight to rotor blades?
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What is an effect of increased angle of attack on the stabiliser?
What is an effect of increased angle of attack on the stabiliser?
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What does dynamic balance of tail rotor blades achieve?
What does dynamic balance of tail rotor blades achieve?
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What role do electronic servo systems play in helicopters?
What role do electronic servo systems play in helicopters?
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What happens to the control movements as a result of maintenance procedures in helicopters?
What happens to the control movements as a result of maintenance procedures in helicopters?
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What is one significant advantage of the NOTAR system compared to conventional tail rotor systems?
What is one significant advantage of the NOTAR system compared to conventional tail rotor systems?
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What does the strake attached to the tail boom primarily achieve?
What does the strake attached to the tail boom primarily achieve?
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How does the Coanda Effect relate to the performance of the strake?
How does the Coanda Effect relate to the performance of the strake?
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What role does the tail thruster cone play in the MD NOTAR system?
What role does the tail thruster cone play in the MD NOTAR system?
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Which component is crucial for ensuring airflow above the tail boom in the NOTAR system?
Which component is crucial for ensuring airflow above the tail boom in the NOTAR system?
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In what condition does the Coanda Effect reach its maximum efficiency for the NOTAR system?
In what condition does the Coanda Effect reach its maximum efficiency for the NOTAR system?
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What is a disadvantage of using a strake on the tail boom?
What is a disadvantage of using a strake on the tail boom?
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What is the main purpose of the NOTAR's anti-torque system?
What is the main purpose of the NOTAR's anti-torque system?
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What factor significantly affects the thrust required by the NOTAR system at higher altitudes?
What factor significantly affects the thrust required by the NOTAR system at higher altitudes?
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How does the circulation-control tail boom contribute to the anti-torque force?
How does the circulation-control tail boom contribute to the anti-torque force?
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What is a key advantage of the Fenestron tail rotor design?
What is a key advantage of the Fenestron tail rotor design?
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What happens to lift forces on either side of the tail boom under normal downwash conditions?
What happens to lift forces on either side of the tail boom under normal downwash conditions?
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What is one benefit of the NOTAR system in terms of control during sideways flight?
What is one benefit of the NOTAR system in terms of control during sideways flight?
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What design factor contributes to the airflow management of the NOTAR system?
What design factor contributes to the airflow management of the NOTAR system?
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Why is the tail rotor in conventional rotorcraft subjected to confused airflows?
Why is the tail rotor in conventional rotorcraft subjected to confused airflows?
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What is the main purpose of the collective control in a helicopter?
What is the main purpose of the collective control in a helicopter?
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Which flight control system primarily directs the helicopter's yaw?
Which flight control system primarily directs the helicopter's yaw?
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What mechanism do boosted flight controls typically use to enhance pilot control?
What mechanism do boosted flight controls typically use to enhance pilot control?
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How does the cyclic control affect the rotor blade angle during flight?
How does the cyclic control affect the rotor blade angle during flight?
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What occurs if a helicopter's hydraulic system fails?
What occurs if a helicopter's hydraulic system fails?
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What allows a pilot to control the altitude of the helicopter?
What allows a pilot to control the altitude of the helicopter?
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What is a significant advantage of using boosted flight controls in helicopters?
What is a significant advantage of using boosted flight controls in helicopters?
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What component adjusts the direction of the swashplate in the cyclic control system?
What component adjusts the direction of the swashplate in the cyclic control system?
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How does moving the cyclic control forward affect the helicopter?
How does moving the cyclic control forward affect the helicopter?
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What is the function of changing the pitch of individual rotor blades prior to cyclic control displacement?
What is the function of changing the pitch of individual rotor blades prior to cyclic control displacement?
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What effect does decreasing the pitch angle of rotor blades have?
What effect does decreasing the pitch angle of rotor blades have?
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What occurs when the collective pitch control is raised?
What occurs when the collective pitch control is raised?
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What is the role of the horizontal stabiliser in a helicopter?
What is the role of the horizontal stabiliser in a helicopter?
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How does the cyclic control affect the helicopter’s lift?
How does the cyclic control affect the helicopter’s lift?
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What happens to rotor RPM when pitch increases?
What happens to rotor RPM when pitch increases?
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What is a potential effect of the tail rotor being too high?
What is a potential effect of the tail rotor being too high?
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How does the collective lever interact with the throttle control on piston engine helicopters?
How does the collective lever interact with the throttle control on piston engine helicopters?
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What design feature can some newer helicopters utilize for the horizontal stabiliser?
What design feature can some newer helicopters utilize for the horizontal stabiliser?
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What is a significant result of increased pitch angle in rotor blades?
What is a significant result of increased pitch angle in rotor blades?
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What effect does lateral movement of the cyclic control have on the helicopter?
What effect does lateral movement of the cyclic control have on the helicopter?
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Why is it important for the pitch of rotor blades to change simultaneously in the collective system?
Why is it important for the pitch of rotor blades to change simultaneously in the collective system?
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What is the primary function of the throttle during a high side governor failure?
What is the primary function of the throttle during a high side governor failure?
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Why can't the throttle be used to correct for a low side governor failure?
Why can't the throttle be used to correct for a low side governor failure?
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What mechanism prevents a pilot from flaming out the engine when throttling from 'flight' to 'idle'?
What mechanism prevents a pilot from flaming out the engine when throttling from 'flight' to 'idle'?
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What is the role of the correlating unit in a piston engine helicopter?
What is the role of the correlating unit in a piston engine helicopter?
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What ensures moisture protection in adjustable push-pull tubes?
What ensures moisture protection in adjustable push-pull tubes?
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Which component is important for confirming the security and integrity of torque tubes?
Which component is important for confirming the security and integrity of torque tubes?
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What is the primary function of bellcranks in a helicopter's flight control system?
What is the primary function of bellcranks in a helicopter's flight control system?
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What operation does the RPM adjustment button facilitate?
What operation does the RPM adjustment button facilitate?
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What happens when collective is pulled up in a gas turbine helicopter?
What happens when collective is pulled up in a gas turbine helicopter?
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What is the purpose of the mixer box in relation to flight control systems?
What is the purpose of the mixer box in relation to flight control systems?
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How is engine cooling achieved using the starter in a helicopter?
How is engine cooling achieved using the starter in a helicopter?
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What characterizes the construction of the push-pull tubes used in cyclic and collective systems?
What characterizes the construction of the push-pull tubes used in cyclic and collective systems?
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What is the effect of increasing all blade angles generally referred to as up collective?
What is the effect of increasing all blade angles generally referred to as up collective?
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What is the main purpose of using spherical bearings in the construction of bellcranks?
What is the main purpose of using spherical bearings in the construction of bellcranks?
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What is the main function of the mixer box in helicopters?
What is the main function of the mixer box in helicopters?
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What does the gradient unit provide to the pilot during flight?
What does the gradient unit provide to the pilot during flight?
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How does the swashplate control the rotor thrust?
How does the swashplate control the rotor thrust?
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Which factor does NOT affect the adjustment of the swashplate?
Which factor does NOT affect the adjustment of the swashplate?
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During takeoff in U.S. made helicopters, which pedal must the pilot depress to add pitch to the tail rotor?
During takeoff in U.S. made helicopters, which pedal must the pilot depress to add pitch to the tail rotor?
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What is the primary purpose of anti-torque control pedals?
What is the primary purpose of anti-torque control pedals?
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What does trimming a helicopter typically require from the pilot?
What does trimming a helicopter typically require from the pilot?
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What does the pitch horn's position on the rotor blade control?
What does the pitch horn's position on the rotor blade control?
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What enhances the feel of movement for the pilot in helicopters with hydraulic controls?
What enhances the feel of movement for the pilot in helicopters with hydraulic controls?
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What must the pilot do to change the attitude of the helicopter when it is flying nose-heavy?
What must the pilot do to change the attitude of the helicopter when it is flying nose-heavy?
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What effect does lowering the collective lever have on the swashplate?
What effect does lowering the collective lever have on the swashplate?
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What is one primary function of the trim motor in a helicopter?
What is one primary function of the trim motor in a helicopter?
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Which element allows for the upward or downward movement of the swashplate?
Which element allows for the upward or downward movement of the swashplate?
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Which statement best describes the function of the anti-torque control during cruising flight?
Which statement best describes the function of the anti-torque control during cruising flight?
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What must rigging procedures for helicopters adhere to?
What must rigging procedures for helicopters adhere to?
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What is typically used to ensure the cyclic control is centered during rigging?
What is typically used to ensure the cyclic control is centered during rigging?
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Which tool is commonly used to determine the angles in the rigging process?
Which tool is commonly used to determine the angles in the rigging process?
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What is a critical requirement when making minor adjustments during the rigging process?
What is a critical requirement when making minor adjustments during the rigging process?
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What is the primary purpose of rigging jigs and pins in the rigging process?
What is the primary purpose of rigging jigs and pins in the rigging process?
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Which item is essential for leveling the helicopter during rigging?
Which item is essential for leveling the helicopter during rigging?
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When setting up the rotor during rigging, what is the first step?
When setting up the rotor during rigging, what is the first step?
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What common equipment might be utilized to verify the required dimensions during rigging?
What common equipment might be utilized to verify the required dimensions during rigging?
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Which statement is true regarding the rigging process of the cyclic system?
Which statement is true regarding the rigging process of the cyclic system?
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What should be observed when adjusting the flight controls after rigging?
What should be observed when adjusting the flight controls after rigging?
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What is the primary function of the anti-torque rotor?
What is the primary function of the anti-torque rotor?
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What does translating tendency refer to in helicopter flight?
What does translating tendency refer to in helicopter flight?
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Which of the following systems eliminates the need for a tail rotor?
Which of the following systems eliminates the need for a tail rotor?
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How is directional control achieved in single main rotor helicopters?
How is directional control achieved in single main rotor helicopters?
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What mechanical configuration does a conventional tail rotor depend upon?
What mechanical configuration does a conventional tail rotor depend upon?
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What effect does increasing the distance of the tail rotor from the mast have?
What effect does increasing the distance of the tail rotor from the mast have?
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What is a characteristic of the Fenestron tail rotor?
What is a characteristic of the Fenestron tail rotor?
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What is the primary role of the pitch change assembly in the tail rotor?
What is the primary role of the pitch change assembly in the tail rotor?
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What stabilizing effect does the tail rotor aim to provide when a helicopter is in hover?
What stabilizing effect does the tail rotor aim to provide when a helicopter is in hover?
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What are the two primary forces acting on a helicopter when it first lifts off the ground?
What are the two primary forces acting on a helicopter when it first lifts off the ground?
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What technological feature is utilized in the NOTAR system to create directional control?
What technological feature is utilized in the NOTAR system to create directional control?
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What is a major challenge in designing helicopter rotor systems?
What is a major challenge in designing helicopter rotor systems?
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How does shifting the cyclic control to the left correct translating tendency?
How does shifting the cyclic control to the left correct translating tendency?
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What mechanism is used in helicopter pedals to adjust tail rotor thrust?
What mechanism is used in helicopter pedals to adjust tail rotor thrust?
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What is the primary function of bias control in helicopters?
What is the primary function of bias control in helicopters?
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Which system provides inputs to the hydraulic actuating arms to maintain the helicopter in a desired configuration?
Which system provides inputs to the hydraulic actuating arms to maintain the helicopter in a desired configuration?
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What is the purpose of horizontal stabilisers in helicopters?
What is the purpose of horizontal stabilisers in helicopters?
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What is the function of synch elevators in helicopter design?
What is the function of synch elevators in helicopter design?
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How is static balance typically achieved for helicopter blades?
How is static balance typically achieved for helicopter blades?
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What is one method for balancing tail rotor blades?
What is one method for balancing tail rotor blades?
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What is the significance of rigging in helicopter control systems?
What is the significance of rigging in helicopter control systems?
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Which of the following statements about the balancing procedure is false?
Which of the following statements about the balancing procedure is false?
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What impact does rearward flight have on stabilisers?
What impact does rearward flight have on stabilisers?
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What is the method of dynamic balance commonly used for?
What is the method of dynamic balance commonly used for?
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What role do computer-controlled inputs play in modern helicopters?
What role do computer-controlled inputs play in modern helicopters?
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Which aspect is a primary consideration when designing vertical stabilisers for helicopters?
Which aspect is a primary consideration when designing vertical stabilisers for helicopters?
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During the balancing procedure for tail rotors, why is adding unauthorized weight dangerous?
During the balancing procedure for tail rotors, why is adding unauthorized weight dangerous?
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What is a primary function of modern electronic stabilisation in helicopters?
What is a primary function of modern electronic stabilisation in helicopters?
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What benefit does the Fenestron tail rotor provide compared to conventional tail rotors?
What benefit does the Fenestron tail rotor provide compared to conventional tail rotors?
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What is the purpose of the canted tail rotor in helicopters like the UH-60 ‘Blackhawk’?
What is the purpose of the canted tail rotor in helicopters like the UH-60 ‘Blackhawk’?
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In a tandem rotor helicopter, what dictates directional stability?
In a tandem rotor helicopter, what dictates directional stability?
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What is a primary advantage of the intermeshing rotor design?
What is a primary advantage of the intermeshing rotor design?
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How does the contra-rotating rotor system achieve directional control?
How does the contra-rotating rotor system achieve directional control?
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What component is essential for the operation of boosted flight controls?
What component is essential for the operation of boosted flight controls?
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What does the accumulator in a boosted flight control system help to maintain?
What does the accumulator in a boosted flight control system help to maintain?
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What is a primary benefit of the fly-by-wire control system in helicopters?
What is a primary benefit of the fly-by-wire control system in helicopters?
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What type of rotor system does the Kaman K-Max utilize?
What type of rotor system does the Kaman K-Max utilize?
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What factor primarily influences the pressure settings of hydraulic systems in helicopters?
What factor primarily influences the pressure settings of hydraulic systems in helicopters?
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What function do the filters in the boosted flight control system serve?
What function do the filters in the boosted flight control system serve?
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What is the primary purpose of the relief valve in a hydraulic system?
What is the primary purpose of the relief valve in a hydraulic system?
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What kind of configuration is typical in a helicopter with dual rotors?
What kind of configuration is typical in a helicopter with dual rotors?
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What is the disadvantage of the conventional tail rotor design?
What is the disadvantage of the conventional tail rotor design?
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What is one key advantage of the NOTAR system over conventional tail rotors?
What is one key advantage of the NOTAR system over conventional tail rotors?
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Which component of the MD NOTAR system helps to reduce vibration?
Which component of the MD NOTAR system helps to reduce vibration?
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What is the primary purpose of the strake attached to the NOTAR system?
What is the primary purpose of the strake attached to the NOTAR system?
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How does the Coanda Effect contribute to the NOTAR system?
How does the Coanda Effect contribute to the NOTAR system?
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What is a disadvantage associated with the strake in the NOTAR system?
What is a disadvantage associated with the strake in the NOTAR system?
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What role does the fan play in the NOTAR system?
What role does the fan play in the NOTAR system?
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In the NOTAR system, what causes the tail boom to move to the right?
In the NOTAR system, what causes the tail boom to move to the right?
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Which statement is true regarding the effects of wind on the strake?
Which statement is true regarding the effects of wind on the strake?
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What does the circulation-control tail boom do in the NOTAR system?
What does the circulation-control tail boom do in the NOTAR system?
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Which feature of the Fenestron tail rotor contributes to its effectiveness?
Which feature of the Fenestron tail rotor contributes to its effectiveness?
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What primarily assists the NOTAR system in achieving directional stability?
What primarily assists the NOTAR system in achieving directional stability?
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Which aspect limits the performance of a conventional tail rotor?
Which aspect limits the performance of a conventional tail rotor?
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What factor does the NOTAR system significantly reduce, especially at higher weights and altitudes?
What factor does the NOTAR system significantly reduce, especially at higher weights and altitudes?
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What happens to the downwash effect on the strake as sideways speed increases?
What happens to the downwash effect on the strake as sideways speed increases?
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Study Notes
Flight Control Systems
- Helicopters have three primary flight controls: cyclic, collective, and anti-torque/directional.
- Cyclic controls pitch and roll axes.
- Collective controls the pitch of main rotor blades, allowing for ascent and descent.
- Anti-torque/Directional counteracts torque of the main rotor and provides directional control in flight about the yaw axis.
Automatic Flight Control Systems (AFCS)
- AFCS allows for control of the helicopter's altitude, attitude, and direction.
- Altitude is controlled by varying the pitch of the rotor blades to produce more or less thrust.
- Attitude is controlled by adjusting the pitch of the rotor blades to achieve a specific tilt or angle of the aircraft.
- Direction is controlled by adjusting the pitch of the tail rotor to counteract the torque of the main rotor.
Boosted Flight Controls
- These systems enhance control efficiency by using hydraulic, electro-mechanical, or electro-hydro-mechanical servos and actuators.
- They are designed to overcome flight loads at high speed and weight, ensuring safe and effective control.
- Hydraulic servo jacks are commonly used to assist the pilot in controlling the pitch of the rotor blades.
- Backup hydraulic systems provide redundancy in case of failure.
Cyclic Control
- The cyclic control column tilts the stationary plate of the swashplate, which then affects the rotating plate and alters the pitch of each blade throughout its rotation.
- It's used to tilt the rotor disc, thereby changing thrust and lift, causing the helicopter to move in the direction of the tilted disc.
- It can be moved forward, backward, left, and right to control the helicopter's movement.
Collective Control
- The collective pitch control (collective lever) simultaneously changes the pitch of all main rotor blades collectively, irrespective of their position.
- It's located on the left side of the pilot's seat and controls helicopter climb or descent by altering the collective pitch of the blades.
- This change in angle of attack affects the rotor RPM.
- For helicopters with piston engines, a correlating unit adjusts throttle to maintain consistent rotor RPM.
- For gas turbine helicopters, a second fuel governor or anticipators help maintain RPM.
Systems Components: Cyclic & Collective
- Push-pull Tubes: These tubes transfer motion from the pilot controls to the flight control system.
- Torque Tubes: These tubes, installed perpendicular to the helicopter's centerline, transmit rotary motion into linear motion – for example, influencing the collective pitch control.
- Bellcranks: Bellcranks redirect the motion of push-pull rods, altering travel and providing mechanical leverage within the system.
- Mixer Box: This component ensures the collective input does not affect the cyclic input when the two controls are used together.
- Gradient Units: These create artificial feel for the controls, which could otherwise feel numb when hydraulic boost is used.
- Swashplate: This crucial component, consisting of a stationary and rotating plate, transmits the pilot's cyclic and collective inputs to the rotor blades.
Anti-Torque Control
- The anti-torque pedals, commonly called tail rotor pedals, control the tail rotor's pitch.
- This mechanism counteracts the torque of the main rotor, preventing uncontrolled yaw (rotation) of the helicopter.
- The control allows precise directional control throughout flight, including during takeoff, where maximum tail rotor pitch is needed.
Anti-Torque Control
- Helicopters use an anti-torque device (e.g., tail rotor) to counteract the torque produced by the main rotor.
- The tail rotor produces thrust in the opposite direction of the main rotor rotation to prevent the helicopter from rotating in the opposite direction.
- Torque can be countered by using two rotors turning in opposite directions, like in Tandem Rotor Helicopters (CH-47 Chinook) or Intermeshing Rotor Helicopters (Kaman K-Max).
Translating Tendency (Tail Rotor Drift)
- During takeoff, there's a tendency for the helicopter to drift to the right due to uneven forces from the main rotor torque and tail rotor thrust.
- This tendency is corrected by moving the cyclic stick to the left, tilting the rotor disc slightly left, and stopping the drift.
- Some designs automatically correct tail rotor drift by tilting the main rotor mast slightly left or using a bias in the cyclic control mechanism.
Rolling Tendency
- After correcting for translating tendency, a rolling tendency emerges due to the horizontal components of the rotor thrust and tail rotor thrust forming a couple.
Tail Rotor Configuration
- Various types of anti-torque tail rotor control systems exist:
- Conventional tail rotor: Most common design, driven by the main transmission, and provides directional control through pedal input.
- NOTAR (NO TAil Rotor): System eliminates the tail rotor, using a fan inside the tailboom to create airflow for anti-torque and directional control.
- Fenestron (Fantail) tail rotor: Shrouded tail rotor offers protection, quieter operation, and potential for greater effectiveness.
NOTAR System Components
- NOTAR systems comprise:
- Air intake: At the top rear of the fuselage, feeding the fan.
- Fan: Driven by the main gearbox, generating low-pressure air.
- Slots: Allow air to escape, energizing the boundary layer of the main rotor downwash.
- Tail thruster cone: Directs high-speed air through a "direct jet thruster" for control.
- Fixed baffle plates: Adjust airflow before exiting the thruster cone.
- Movable vertical stabilizers: Play a role during forward flight.
- Strake: On the opposite side of the slots, used to "spoil" the downwash for anti-torque.
Strakes and Anti-Torque
- Strakes, attached lengthwise to the tail boom, create a lift force by disrupting the airflow, reducing the required tail rotor thrust.
- This effect, known as the Coanda Effect, is most prominent during hover but lessens with forward flight.
- Strakes also improve directional stability, particularly during sideways flight.
Fenestron Tail Rotor
- Shrouded tail rotor offers protection and improved airflow compared to conventional tail rotors.
- Minimizes accidental damage and produces comparable thrust with a smaller rotor.
- The vertical stabiliser provides forward flight torque compensation.
Canted Tail Rotor
- Angles the tail rotor from the vertical, providing lifting force in a hover, as seen in the UH-6O "Blackhawk" helicopter.
Dual Rotors
- Utilize two rotors turning in opposite directions to counteract torque, offering alternatives to conventional tail rotors.
- Tandem Rotor Helicopter: Rotors at front and rear of the fuselage provide directional stability based on individual thrust.
- Intermeshing Rotor Design: Rotors mounted side-by-side on the fuselage.
- Contra-rotating Rotors: Two main rotors above and below the fuselage, driven by coaxial shafts provide directional control by adjusting pitch on each rotor.
Boosted Flight Controls
- Provide enhanced control response through a hydraulic system.
- System components include:
- Hydraulic Pump: Driven by the transmission, providing power during autorotation.
- Reservoir: Contains fluid, a screen for filtration, and a sight gauge for level monitoring.
- Relief Valve: Sets system pressure, typically between 250 psi and 2000 psi.
- Filters: Protect the hydraulic system, often with warning mechanisms for blockage.
- Accumulators: Store pressurized fluid to provide extra power when needed.
- Actuators: Move control surfaces, equipped with pilot and irreversible valves for precise operation.
- Servo Actuators: Assist pilot control, prevent rotor feedback, and enhance responsiveness.
Flight Control Fly-By-Wire
- Electronically connects cockpit control surfaces to actuators, for greater precision and performance.
- Eliminates mechanical linkages, reducing weight and maintenance.
- Uses electrical signals and transducers to measure pilot commands and operate actuators.
Trim Controls
- Helicopters don't have trim tabs, but trim control is achieved through:
- Bias Control: Adjusting tension in linkages to adjust control stick positions, minimizing pilot input.
- Electronic Servo Systems: Computer-controlled inputs to actuators maintain desired aircraft configurations.
Horizontal Stabilisers
- Provide stability by preventing follow-through pitching movements, particularly during gust-induced blow-back.
- Increase lift at the rear of the aircraft, helping to control pitch and maintain stability.
Stabilisers
- Stabilisers dampen dynamic oscillations by stabilising the fuselage and the disc.
- They are important for longitudinal stability in forward flight.
- They are detrimental to rearward flight, as they accentuate longitudinal oscillations.
- Vertical stabilisers are fitted at odd angles to account for airflow from forward flight and rotor downwash.
Synch Elevators
- Synch elevators are stabilisers that pitch up and down with fore/aft cyclic movements.
- They enhance stabiliser response at varying airspeeds.
Helicopter Stability
- It is difficult to provide satisfactory longitudinal stability even with the best designed stabilisers.
- Modern helicopters use electronic stabilisation systems, such as gyro-controlled autopilots and computers, to provide inputs into the main control linkage system.
Balancing
- Drive shafts are normally dynamically balanced during manufacturing to reduce vibration.
- Tail rotor blades require static balance, both span-wise and chordwise, and dynamic balance.
Static Balance
- Static balance can be accomplished using specific or universal balancing equipment.
- The balancing procedure is similar for tail rotors, but the balancing point may vary.
Blades Balance
- Older blades have spanwise weight placed on blade tips and chordwise weights added to the blade.
- Modern blades have weight added to the blade hub.
- Blades are balanced in either a vertical or horizontal position.
Balancing Equipment
- Balancing equipment is often available from the manufacturer or as universal equipment.
- Universal balancers operate using a disc attached to a cable and dampened in oil.
- Static balancing must be done in a closed room for accuracy.
Control Rigging
- Maintenance for control rigging usually involves removal and replacement of components.
- Control movements are critical and require adjustments to ensure correct pitch and cyclic travel.
- Rigging procedures are often required after removal and replacement of components.
- Early helicopters had complex rigging due to large tolerances in fuselage construction.
Rigging Procedures
- Rigging procedures must be in accordance with the manufacturer’s instructions.
- Minor adjustments may be required after initial flight, but these must be made according to the maintenance manual and in small increments.
Rigging Equipment
- Special tools such as jigs, rigging pins, and holding fixtures are often required for rigging.
- Other items, such as mast alignment, may need to be checked.
- Equipment for rigging cyclic and collective varies with helicopter type.
- Common equipment includes a measuring scale and a universal protractor.
Cyclic Control Rigging
- The cyclic control is placed in the neutral position, typically straight up.
- Rods are adjusted to check points, such as bellcranks, servo units, and the swashplate.
- The rotor may be held in position or checked with a protractor.
- Extreme positions are set by stops located on bellcranks or the swashplate.
Flight Control Systems
- Helicopters have three basic flight controls: cyclic, collective, and anti-torque/directional.
- The cyclic controls pitch and roll by tilting the rotor disc.
- The collective controls the helicopter’s altitude by increasing or decreasing the pitch of all main rotor blades simultaneously.
- The anti-torque/directional control counteracts the main rotor’s torque and provides directional control about the yaw axis.
- Flight control systems allow both pilots and Automatic Flight Control Systems (AFCS) to control altitude, attitude, and direction.
- Boosted flight controls are designed to overcome the flight loads encountered at high speeds and high all-up weight.
- They utilize hydro-mechanical, electro-mechanical, and electro-hydro-mechanical servos and actuators to assist the pilot.
Cyclic Control
- The cyclic control column alters the plane of the stationary plate of the swashplate, changing the blade angle as the rotor spins.
- The cyclic control is used to tilt the tip path plane of the main rotor, which influences the helicopter's direction.
- Movement of the cyclic forward or aft tilts the disc and moves the helicopter in that direction.
- Moving the cyclic from side to side causes a sideways movement of the helicopter.
- Gyroscopic precession requires the pitch of each rotor blade to be changed 90 degrees prior to the movement of the cyclic stick.
- Some helicopters have a horizontal stabilizer on the tail connected to the cyclic linkage.
- This stabilizer, often called an elevator, helps maintain a level flight attitude and can be adjusted to control the tail's position for different flight phases.
Collective Control
- The collective pitch control lever adjusts the pitch angle of all main rotor blades simultaneously.
- Raising the collective increases blade pitch, increasing lift and potentially reducing rotor RPM.
- Lowering the collective decreases blade pitch, decreasing lift and potentially increasing rotor RPM.
- To maintain constant rotor RPM, the throttle control or a governor adjusts engine power to compensate for changes in drag caused by collective pitch adjustments.
- The collective lever is connected to the rotor system via push-pull tubes.
- Rotor RPM compensation is achieved through correlating units or governors, which automatically adjust engine power or fuel flow.
Swashplate
- The swashplate consists of two “stars” (or orbits) that transfer pilot input to the rotor blades.
- The stationary plate is connected to the pilot controls, and the rotating plate is connected to the rotor blades via pitch links.
- Movements of the stationary plate, from both the cyclic and collective, are transferred to the blades through the rotating plate.
Anti-Torque Control
- The anti-torque pedals, also known as tail rotor pedals or rudder pedals, control the pitch of the tail rotor.
- The tail rotor counteracts the main rotor's torque and provides directional control.
- During takeoff, the tail rotor requires the highest positive pitch due to maximum main rotor power.
- On U.S. made helicopters (counterclockwise rotating), depressing the left pedal increases tail rotor pitch.
Anti-Torque
- Helicopters use a tail rotor or other anti-torque mechanisms to counteract torque from the main rotor.
- The main rotor generates torque that rotates the aircraft in the opposite direction of the rotor's spin.
- The tail rotor, positioned to the right, produces thrust to the right, creating a moment (force over distance) to counter the main rotor torque.
- Translating tendency (tail rotor drift) occurs because of uneven forces applied by the main rotor and tail rotor: two to the right and one to the left.
Rolling Tendency
- After the rotor disc tilts slightly left to correct translating tendency, a rolling tendency to the left is created.
- This occurs because the horizontal component of total rotor thrust points left while tail rotor thrust points right.
- These forces form a couple tending to roll the helicopter left.
Tail Rotor Configuration
- The tail rotor provides directional control for single-rotor helicopters.
- Pedals change the pitch of the tail rotor, altering the helicopter's heading.
Conventional Tail Rotor
- Powered from the main transmission of the helicopter.
- Must rotate at all times during flight, even if the engine is not operational.
NOTAR System
- Eliminates traditional tail rotors.
- McDonnell Douglas developed the system.
- Utilizes a fan inside the tailboom to generate high-volume, low-pressure air exiting through slots, creating a boundary layer flow of air.
- Boundary layer alters airflow around the tailboom, producing thrust opposite the main rotor torque.
- Direct jet thruster at the end of the tailboom provides directional yaw control.
NOTAR Advantages
- Safer operation compared to conventional tail rotors.
- Eliminates tail rotor strikes and foreign object damage.
- Improved control in crosswinds, reduced vibration.
NOTAR Components
- Air intake at the rear of the fuselage.
- Fan driven by the main gearbox.
- Two slots along the right-hand side of the tail boom.
- Tail thruster cone.
- Fixed baffle plates.
- Movable vertical stabilizers.
- Strake on the left-hand side of the tail boom.
Strakes and Anti-Torque
- The strake "spoils" the downward airflow on the left side of the tail boom, reducing lift and generating a force to the right.
- This offsets the main rotor torque.
- The strake utilizes the Coanda effect (airflow curving around a surface creates lift) to increase lift on the right side while reducing lift on the left side.
- Benefits include reduced tail rotor blade pitch angles, less power required, and improved anti-torque at higher weights.
Fenestron Tail Rotor
- Shrouded tail rotor, providing protection from foreign object damage and blade injuries.
- Eliminates lift asymmetry, making flapping unnecessary.
- More effective compared to conventional tail rotors of a similar diameter.
Canted Tail Rotor
- Angled from the vertical, providing anti-torque reaction and some lifting force in a hover.
- Example: UH-60 Blackhawk helicopter.
Dual Rotors
- Counteracts main rotor torque using two rotors turning in opposite directions.
- Can be coaxial (mounted one above the other) or tandem (one at the front, one at the rear).
Tandem Rotor Helicopter (CH-47 Chinook)
- Uses two counter-rotating rotors located at the front and rear of the fuselage.
- Directional stability depends on which rotor produces more thrust.
Intermeshing Rotor Design (Kaman K-Max)
- Two intermeshing counter-rotating rotors mounted next to each other on the fuselage.
Contra-Rotating Rotors
- Two main rotor systems mounted above and below each other on a coaxial mast, rotating in opposite directions.
- Directional control achieved by changing pitch on one disc and decreasing pitch on the other.
Boosted Flight Controls
- Hydraulic system containing a pump, reservoir, relief valve, filters, accumulators, and actuators.
Boosted Flight Controls Pumps
- Driven by the transmission for hydraulic strength during autorotation.
Boosted Flight Controls Reservoir
- Contains a screen and sight gauge for fluid level inspection.
Boosted Flight Controls Relief Valve
- Controls system pressure, varying from 250 psi to 2000 psi.
Boosted Flight Controls Filters
- May have pop-out warning buttons to indicate blockage.
Boosted Flight Controls Accumulators
- Conventional piston type, not present on smaller systems.
Boosted Flight Controls Actuators
- Move pistons or cylinders, equipped with pilot and irreversible valves.
Boosted Flight Controls Servo Actuators
- Assist pilots with control movements and prevent rotor feedback.
Flight Control Fly-By-Wire
- Electronically links cockpit controls with actuators, allowing for precise maneuvering based on pilot input.
- Reduces weight and maintenance costs, improves performance.
Trim Controls
- Helicopters do not have trim tabs.
- Trimming is achieved through bias control or electronic servo systems.
Bias Control
- Adjust tension in linkages between pilot controls and blade control mechanisms to achieve a desired configuration.
Electronic Servo Systems
- Computer-based inputs to hydraulic actuators maintain desired configuration.
Horizontal Stabilisers
- Stabilize the fuselage, preventing follow-through pitching movements during flap-back occurrences.
- Increase lift at the rear of the aircraft to counter nose pitch-up during forward flight.
Stabilisers
- Stabilisers help helicopters maintain stability and control
- Stabilisers dampen dynamic oscillations by stabilising the fuselage and the disc
- They're beneficial in forward flight but can cause issues in rearward flight
- In rearward flight, the stabiliser intensifies longitudinal oscillations, increasing the risk of dangerous situations
- Vertical stabilisers are angled based on airflow from forward flight and rotor downwash
- Stabilisers are typically designed to function best at normal forward cruise speeds
Synch Elevators
- Synch elevators are a type of stabiliser that pitch up and down with fore/aft cyclic movements
- They enhance stabiliser response across varying airspeeds
Modern Stabilisation Systems
- Modern helicopters use electronic stabilisation, such as gyro-controlled autopilots and computers, to provide inputs into the main control linkage system
Tail Rotor Balancing
- Tail rotor drive shafts are dynamically balanced during manufacturing to reduce vibration
- Tail rotor blades are balanced against a master blade and require static and dynamic balancing
- Static balance involves ensuring uniform weight distribution spanwise and chordwise
- Modern blades often have weight added to the hub rather than the tips
- Balancing equipment is usually available from the manufacturer or as universal options
- Balancing procedures are similar for tail rotors and main rotors, but the balancing point may vary
Tail Rotor Balancing Procedures
- Blades are balanced in either a vertical or horizontal position using universal balancers similar to those used for main rotors
- Balancing is done in a closed room to ensure accuracy due to sensitivity to air currents
- Balancing involves adding weight to the blade until a perfect circle is visible between the balancer's disc and collar
Control Rigging
- Maintenance of control rigging typically involves removing and replacing components
- Rigging involves adjusting components to ensure correct pitch on the collective and proper cyclic travel within tolerances
- Initial rigging procedures can be complex due to design and manufacturing tolerances in older helicopters
- Rigging must follow manufacturer instructions to avoid unsafe flight characteristics
- Minor adjustments may be necessary after the initial flight, but must be done in accordance with the maintenance manual and in small increments
Rigging Equipment
- Rigging procedures require various equipment, including jigs, rigging pins, holding fixtures, and special tools
- Depending on the helicopter, levelling jacks, measuring scales, universal protractors, and rigging jigs/pins are required
- Jigs and pins hold bellcranks in place while adjusting rods
Cyclic Control Rigging
- The cyclic control is typically centred in a neutral position, then rods are adjusted to specific check points
- The servo valve is set to neutral
- The actuator is attached to the swashplate, set to a predetermined angle using a protractor
- Control rods are then adjusted to the rotor, which might be held in place or checked for a neutral position
- Extreme positions (stops) are set on the bellcranks or the swashplate.
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Description
Explore the fundamental flight control systems of helicopters, including cyclic, collective, and anti-torque controls. This quiz also covers Automatic Flight Control Systems (AFCS) and the enhanced capabilities provided by boosted flight controls. Test your knowledge on how these systems work together to manage altitude, attitude, and directional control.