Helicopter Aerodynamics: Flight Theory & Components

Which of the following components is NOT typically considered a basic part of a helicopter?

The first civilian helicopter to be certified in the United States was the Bell Helicopter Model 47. What was its type certificate number?

What primary angle is defined as the angle between the relative wind vector and the chord line of the blade?

What term describes the axis on which the rotor blade rotates to change the angle of the blade chord line, influencing the blade angle of attack?

Most helicopters utilize which of the following blade shapes to mitigate imbalance and vibration issues?

What action creates relative wind for an airfoil?

Which of the following is the term that describes the imaginary circular plane outlined by the rotor blade tips during a cycle of rotation?

What characteristic of the rotational relative wind defines its velocity distribution along the rotor blade?

Why do manufacturers use geometric twist or blade taper in rotor blade design?

In the context of rotor blades, what does blade tracking refer to?

What force, acting on rotor blades, is the result of the mass of the blades being sent straight out from the center of rotation?

What term is used to describe the upward flexing of rotor blades?

What is the primary purpose of droop restraints in a helicopter rotor system?

How does the effect of gyroscopic precession manifest in a helicopter rotor system?

What is the purpose of changing blade angles to cause an upward movement at the rear side of the disk and a downward movement at the front?

In helicopter dynamics, what is the primary cause of retreating blade stall?

What is the impact of Coriolis effect on a rotor blade in a helicopter system?

How does ground effect influence helicopter performance?

What happens when a helicopter in IGE moves at a speed greater than 3 to 5 miles per hour?

What condition leads to translational lift in a helicopter?

Which of the following best describes ground resonance in helicopters?

What action might stop the condition when the forces of vibration cannot be absorbed by the strut or tire and a counter-wave is sent back through the helicopter?

A change in which factor leads to dynamic instability in helicopters?

In the context of helicopter dynamics, what will happen to the disk in a wind gust?

Which of the following is a measure used to stabilize helicopters?

In autorotation, what happens to the airflow through the main rotor?

During autorotation, what consequence results if the main rotor RPM (Nr) increases too much?

What defines the 'Deadman's Curve' in helicopter operations?

What is the initial step a pilot should undertake upon recognizing engine failure while flying a helicopter?

The rotor is spinning. Newton's third law states that for every action there is an opposite and equal reaction. What term refers to this reaction?

How do tandem main rotor systems counteract torque?

In a climb, hover, or descent, all forces acting on a helicopter are along which axis?

In forward flight, which direction are the resultant vectors oriented for Lift & Thrust?

What happens when a helicopter rotor disk is tilted in directional flight?

Where must the greatest amount of lift be applied relative to the desired high point of the disk?

What is the value of thrust and direction in a hover?

In what conditions must lift and thrust be greater than the helicopter's weight?

What is required to have directional control?

What components helps to stabilize flight?

In a helicopter, if the rotor disk is tilted to the left, which direction will the helicopter move?

What happens to the airflow direction through the rotor system during autorotation?

What is the primary function of droop restraints in a helicopter rotor system?

Which force is primarily responsible for causing the rotor blades to flex upward during rotation?

When a helicopter transitions from a hover to forward flight, what happens to the relative wind on the advancing blade?

In helicopter flight, what is the effect of gyroscopic precession?

What is the purpose of blade tracking in a helicopter rotor system?

Which of the following scenarios describes a helicopter experiencing 'ground effect'?

What is likely to occur if a helicopter experiences excessive main rotor RPM (Nr) during autorotation?

Why do helicopter manufacturers often incorporate geometric twist or blade taper in rotor blade design?

What is primarily affected by the 'pitch angle' on a helicopter rotor blade?

In the context of helicopter aerodynamics, what is 'relative wind'?

What is a primary characteristic of rotational relative wind velocity along a helicopter rotor blade?

Which of the following best describes the term Deadman's Curve in helicopter operations?

What happens to a helicopter rotor disk when it encounters a wind gust, assuming no pilot input?

How do tandem main rotor systems primarily counteract torque effects?

In a tandem rotor helicopter, what control input allows for yaw control?

What is achieved in a tandem rotor helicopter when both rotors are tilted in opposite directions?

How does altering the load on rotating blades in a counter-rotating co-axial rotor system affect the helicopter's flight?

What design feature of the Fenestron system reduces the likelihood of the tail rotor blades coming into contact with people or objects?

What is the primary function of the enclosed variable-pitch composite blade fan in the NOTAR anti-torque system?

In the NOTAR system, how is directional control primarily maintained during forward flight?

An offset mast can correct translating tendency, how does it achieve this?

How does offsetting a vertical stabilizer contribute to reducing power requirements in flight for helicopters using tail rotors?

What is the primary purpose of 'leading and lagging' (or hunting) in a helicopter rotor system?

What distinguishes a 'rigid' rotor system from other types of rotor systems?

In a semi-rigid rotor system, how is the center of mass movement prevented as the blade flaps up?

What feature allows a fully articulated rotor system to undergo pitch change, flapping, and hunting motions?

Which control in a helicopter changes the pitch angle of all the blades equally throughout the 360 degrees of rotation?

How is the movement of the cyclic and collective controls transferred to the rotor system?

In helicopters that use a twist grip on the collective, what is the function of this twist grip on turbine-powered helicopters?

What primary function does the cyclic control serve in a helicopter?

What is the general purpose of a Bell Crank within control systems?

What added benefit is achieved when using Bell Cranks of unequal length?

How does an Idler Type Bellcrank assembly prevent bending?

What is the function of Torque Tubes within a rotor system?

What is the function of Pitch Horns?

What unique action do Control Quadrants perform?

In the construction of helicopters, what is the purpose of Hydraulic Servo Assemblies?

What is the purpose of a mixing unit?

What controls the amount of thrust produced by the anti-torque device?

What component transfers control input movement to the blades?

Tilting both rotor systems in the same direction, the helicopter?

The blades of the Fenestron tail rotor system are located?

The NOTAR system exhausts from which of the following?

What action do the tail rotor pedals perform.?

How does collective pitch function overall?

What is one function of cable systems for tail rotors?

What controls the yaw in hover?

What happens in an articulated rotor system?

In reciprocating engines, the Collective twist grips will?

Why are some Bell cranks drilled out and safety wired?

What control input is primarily utilized for yaw control in a tandem rotor helicopter?

In a counter-rotating co-axial rotor system, how is yaw controlled?

What is a key feature of the Fenestron anti-torque system that enhances safety?

In the NOTAR system, what is the primary function of the enclosed variable-pitch composite blade fan?

Within a helicopter's tail rotor system, what is the purpose of the pilot's foot pedals?

What is the primary purpose of offsetting the mast in some helicopter designs?

Why do some conventional helicopters utilize an offset vertical stabilizer?

What is the purpose of 'leading and lagging,' also known as 'hunting,' in a helicopter rotor system?

In a semi-rigid rotor system, what design feature prevents the center of mass movement as the blade flaps up?

Which of the following describes the primary function of the collective control in a helicopter?

In helicopter flight controls, what function does a Bellcrank typically perform?

What is the main purpose of Hydraulic Servo Assemblies in helicopter construction?

What is the function of a helicopter mixing unit?

How does a conventional helicopter counteract the torque effect produced by the main rotor?

The tail rotor is typically powered by what means?

What is the primary function of the tail rotor pedals in a helicopter?

In what way does increasing the pitch angle on the tail rotor blades affect the helicopter?

What component is directly manipulated to change the pitch angle of the tail rotor blades?

Which of the following best describes the purpose of the tail rotor?

In a typical single main rotor helicopter configuration, what happens if the tail rotor fails?

How is yaw controlled in a helicopter with a traditional tail rotor configuration?

What component connects the main rotor shaft to the tail rotor in a conventionally designed helicopter?

What is the consequence of applying too much anti-torque force with the tail rotor pedals?

Which of the following is a function of synchronized elevators?

What is a primary benefit of using an offset vertical stabilizer in conventional helicopters with tail rotors?

What is the effect of unloading the tail rotor in forward flight?

How does an offset vertical stabilizer contribute to the reduction of power requirements in helicopters using a tail rotor?

During forward flight, an offset vertical stabilizer primarily helps to align the fuselage with the relative wind. What is the direct benefit of this alignment regarding power requirements?

What term describes the methodology of changing the angle of attack of the blades?

How does a pilot use synchronized elevators to maintain longitudinal control?

In the context of helicopter design, how does utilizing an offset vertical stabilizer enhance overall flight performance?

How do synchronized elevators contribute to a helicopter's stability?

For helicopters equipped with an offset vertical stabilizer, what flight condition benefits most from this design?

What primary condition necessitates a disconnect mechanism within a helicopter's rotor system?

In a helicopter equipped with a 'free wheeling unit', when does disengagement between the engine and transmission occur?

How does the rotor system behave during autorotation after the engine disengages?

In a helicopter using a belt drive system, how is the engine disconnected from the rotor system to allow autorotation?

What is the purpose of the 'sprag' assembly in helicopters with a mechanical drive?

During autorotation, what happens to the main gearbox in relation to the engine?

What is the immediate consequence of a disengaged engine during autorotation?

How does the design of a 'free wheeling unit' or 'sprag' assembly contribute to helicopter safety?

Considering the mechanical connection in a helicopter's drive system, what component directly facilitates the disconnection for autorotation?

What design difference would you expect to easily see on belt driven helicopters compared to direct drive to transmission helicopters?

In a helicopter with a belt drive system, if the belt begins to slip during normal operation (excluding autorotation), what is the most likely immediate consequence?

What is the primary advantage of using a belt drive system over a direct drive system in a light helicopter?

In a helicopter employing a belt drive system, how is the anti-torque rotor typically driven?

If a helicopter's belt drive system uses an idler pulley, what is the primary function of this pulley?

What component ensures the engine is disengaged from the rotor system in autorotation in a helicopter with a belt drive?

In a helicopter belt drive system, why is it essential to regularly inspect the condition and tension of the drive belts?

What role does a linear actuator play in a helicopter's belt drive system, if present?

What is one potential disadvantage of using a centrifugal clutch system in conjunction with a belt drive, compared to a direct drive system?

If a helicopter utilizes both a belt drive and a centrifugal clutch system, where is the centrifugal clutch typically located in the power transmission path?

How does the use of a belt drive system in a helicopter influence the design and maintenance of the main rotor gearbox, compared to helicopters without a belt drive?