26 Questions
Which force opposes lift and is caused by the downward pull of gravity?
Weight
What is the force that propels the helicopter through the air?
Thrust
What is drag?
The retarding force created by development of lift and the movement of an object through the air.
Which component of lift is responsible for induced drag?
The rearward inclination of the lift
What happens to induced drag as airspeed increases?
It decreases
What causes the formation of stronger vortices and an increase in induced drag?
An increase in angle of attack
Which of the following is NOT a type of drag in a helicopter?
Thrust drag
What is the load factor of a helicopter in steady-state flight?
1
What is the solidity ratio of a rotor system?
The ratio of rotor blade area to rotor disc area
What is the main factor that determines the majority of lift in a helicopter?
Decreased pressure above the rotor blade
Which one of the following is true about the center of pressure on an airfoil?
The center of pressure is the point where the resultant of all aerodynamic forces are considered to be concentrated.
What is the purpose of bending the trailing edge of an asymmetrical rotor blade?
To increase the stability of the rotor disc.
What is the span of an airfoil?
The distance from the rotor hub to the blade tip.
What is the chord line of an airfoil?
An imaginary straight line drawn from the leading to the trailing edge of the airfoil.
Which of the following statements is true about the angle of attack?
Increasing the angle of attack beyond the critical angle of attack produces a decrease in lift.
What is the Magnus Effect?
A lifting force produced when a rotating cylinder produces a pressure differential.
What is Bernoulli's Principle?
The principle that air flowing over the top surface of an airfoil accelerates and creates a decrease in pressure.
What is the relationship between the angle of attack and the production of lift?
Increasing the angle of attack increases the production of lift.
Due to the downward deflection of the airstream near the rotor blade, the blade operates in an average relative wind that is inclined ______ and rearward near the blade.
downward
The lift produced by the blade is perpendicular to the relative wind, therefore the lift is inclined ______ by the same amount.
aft
The component of lift that is acting in a rearward direction is ______ drag.
induced
As the air pressure differential increases with an increase in angle of attack, stronger vortices form, and ______ drag increases.
induced
Induced drag is the major cause of drag at ______ airspeeds.
lower
True or false: The downward deflection of the airstream near the rotor blade causes the blade to operate in an average relative wind that is inclined downward and rearward near the blade.
True
True or false: As the air pressure differential increases with an increase in angle of attack, stronger vortices form, and induced drag decreases.
False
True or false: Induced drag is the major cause of drag at higher airspeeds.
False
Test your knowledge on the effects of increasing the angle of attack on lift and stalling with this quiz. Learn about the critical angle of attack and how it determines lift production. Explore the progression of the separation point on an airfoil as the angle of attack is increased.
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