# Helicopter Aerodynamics

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## 60 Questions

Weight

### What is the purpose of the antitorque rotor in a helicopter?

To overcome torque

### What is the function of the swash plate assembly in a helicopter?

To transmit cyclic pitch control inputs to the rotor head

In bending

Drag

Induced drag

### What is the relationship between thrust and torque in a helicopter?

Thrust and torque are directly proportional

### What is the purpose of the tail rotor in a helicopter?

To counteract torque-induced turning tendency

Vertical axis

### What is the purpose of the anti-torque system in a helicopter?

To control the yawing movement around the vertical axis

### What is autorotation in a helicopter?

The state of flight where the main rotor system is being turned by the action of the relative wind passing up through the disc, rather than engine power

### What causes the retreating blade stall in a helicopter?

A high angle of attack and slow relative wind speed

### Which one of the following statements about the span of a rotor blade is correct?

The span of a rotor blade is the distance from the blade root to the blade tip.

### What does twisting a rotor blade cause?

Twisting a rotor blade causes it to produce a more even amount of lift along its span.

### What is the pitch angle?

The angle between the blade chord and a reference plane determined by the rotor hub.

### What is the angle of attack?

The angle between the blade chord and the relative wind.

### Which of the following is true about ground effect in helicopter flight?

Ground effect increases lift and reduces induced drag

### What is the term for the difference in lift between the advancing and retreating blades of a helicopter rotor system?

Dissymmetry of lift

Pendular action

The airframe

### Which type of main rotor system allows the blades to move up and down, back and forth, and around the spanwise axis?

Fully articulated

Dragging

Semi-rigid

descends

### What is the pitch angle of a rotor blade?

The angle between the blade chord line and a reference plane

vertical

### What is the angle of attack of a rotor blade?

The angle between the rotor's chord and the relative wind

### Which of the following is NOT a type of anti-torque system used in helicopters?

Dual-rotor system

### How is hovering at a constant altitude achieved in a helicopter?

By generating lift and thrust equal to the weight of the helicopter

### To successfully change the downward flow of air to an upward flow during autorotation, the pitch angle of the main rotor blades must be ______ by lowering the collective pitch.

reduced

The ratio of weight to the total main rotor disc area

vertical

sideward

### What is autorotation in the context of helicopters?

The stage of flight in which the main rotor system is turned by the relative wind

### What is the function of the swash plate assembly in a helicopter?

To transmit cyclic pitch control inputs to the rotor head

Drag

### What is the purpose of the antitorque system in a helicopter?

To overcome torque and prevent the helicopter from turning in the opposite direction of main rotor rotation

### Which of the following is a characteristic of a fully articulated rotor system in a helicopter?

The blades can move up and down, back and forth, and around the spanwise axis

### What is the purpose of dampers in a fully articulated rotor system?

To prevent excessive movement around the drag hinges

### Which of the following is a characteristic of a semirigid rotor system in a helicopter?

The blades are rigidly attached to the main rotor hub

### Which one of the following statements about the solidity ratio is correct?

The solidity ratio is the ratio of the total rotor blade area to the total rotor disk area.

### What is the purpose of the tip-path plane in a helicopter?

The tip-path plane is the imaginary circular plane outlined by the rotor blades tips as they make a cycle of rotation.

### What is the relationship between the angle of attack and lift in a helicopter?

Increasing the angle of attack increases lift, up to a point.

Drag

Weight

Torque

### Which of the following is true about ground effect in helicopter flight?

Ground effect occurs when the helicopter is hovering near the ground, causing an increase in lift and a decrease in induced drag.

### What causes the retreating blade stall in a helicopter?

The relative wind speed acting on the retreating blade is reduced by the helicopter's forward airspeed.

### What is translational lift in helicopter flight?

Translational lift is the additional performance gained from the increase in rotor system efficiency due to accelerated airflow through it.

### Which of the following is true about the Coriolis effect in helicopter rotor blades?

The Coriolis effect causes the rotor blade to accelerate when it flaps down

### What is the purpose of a freewheeling unit in a helicopter?

To allow the main rotor system to continue turning even if the engine is not running

### What causes the nose of a helicopter to pitch down in forward flight?

Applying forward pressure to the cyclic

### What is the function of the antitorque system in a helicopter?

To control the yawing movement around the vertical axis

True

### What is the purpose of the swash plate assembly in a helicopter?

To tilt the main rotor disc and control the pitch attitude

True

True

True

### True or false: The Coriolis effect causes the acceleration or deceleration of the rotor blade in a helicopter.

True

Test your knowledge on rotor blade stalls and the Coriolis effect with this quiz. Learn about the causes and symptoms of retreating blade stall and gyroscopic precession. Discover how the movement of rotor blades affects their center of mass in relation to the axis. Challenge yourself and enhance your understanding of helicopter aerodynamics.

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