Lesson 2 Principles Of Flight

Question 1

What are the four forces of flight?

Answer 1

Lift, Weight, Thrust, Drag

Question 2

What opposes the downward force of weight?

Answer 2

Lift

Question 3

According to Bernoulli’s Principle, what happens as the velocity of a fluid increases?

Answer 3

The pressure decreases

Question 4

What is the practical application of Bernoulli’s Principle in aviation?

Answer 4

Venturi tube and over the airfoil create a low pressure area on top of the airfoil

Question 5

What does Newton’s 3rd Law of Motion state?

Answer 5

For every action, there is an equal and opposite reaction

Question 6

What is weight in the context of aviation?

Answer 6

The mass of the aircraft at 1 gravity, counteracting lift

Question 7

What produces thrust in an aircraft?

Answer 7

The powerplant/propeller or rotor

Question 8

What must be true for an aircraft to maintain constant airspeed?

Answer 8

Thrust must equal drag

Question 9

What is drag?

Answer 9

A rearward, retarding force caused by disruption of airflow

Question 10

Name the four types of drag.

Answer 10

• Profile
• Parasitic
• Induced
• Total

Question 11

What is an airfoil?

Answer 11

A shaped object designed to produce lift when passed through the air

Question 12

What are the two types of airfoil?

Answer 12

• Symmetric
• Asymmetric

Question 13

What is the lift equation?

Answer 13

L=½Px V²xSxCL

Question 14

What does the variable ‘CL’ in the lift equation represent?

Answer 14

Coefficient of lift, or the angle of attack

Question 15

What is blade stall?

Answer 15

Condition where rotor blade operates at an angle of attack greater than maximum, disturbing laminar flow

Question 16

What are the three axes of flight?

Answer 16

Roll, Pitch, Yaw

Question 17

What is the effect of torque in helicopters?

Answer 17

The fuselage wants to turn clockwise as the main rotor turns counterclockwise

Question 18

What counteracts torque-induced yaw in helicopters?

Answer 18

Anti-torque tail rotor

Question 19

What is a fully articulated rotor system?

Answer 19

A system with 3 or more blades that allows independent movement of rotor blades

Question 20

What is a semi-rigid rotor system?

Answer 20

A system with 2 blades mounted to a hub that can tilt on a teeter hinge

Question 21

What describes a rigid rotor system?

Answer 21

Rotors are rigidly mounted to the hub and can only feather

Question 22

What are the pros of a fully articulated rotor system?

Answer 22

• Good control response
• Smooth ride

Question 23

What is ground resonance?

Answer 23

A condition where the aircraft vibrates at a certain frequency due to rotor imbalance

Question 24

What should you do to correct ground resonance if you have power?

Answer 24

Pick up into a hover to rebalance the blades

Question 25

What is sympathetic resonance?

Answer 25

When two objects vibrate in tune either through contact or across a distance

Question 26

Fill in the blank: The center of gravity must be within the limits of the _______.

Answer 26

aircraft

Question 27

What is the primary purpose of the tail rotor?

Answer 27

To counteract torque-induced yaw

Question 28

What causes parasitic drag?

Answer 28

Anything that does not produce lift

Question 29

What is induced drag a byproduct of?

Answer 29

Lift

Question 30

What is total drag?

Answer 30

A combination of all drag on the aircraft

Question 31

What is the relationship between air density and lift capability?

Answer 31

As air density decreases, lift capability decreases

Question 32

What is the center of pressure?

Answer 32

The point along the chord line of an airfoil through which aerodynamic forces act

Question 33

What is the angle of attack (AOA)?

Answer 33

The angle between the resultant relative wind and chord line

Question 34

What is rotational relative wind?

Answer 34

The airflow relative to an airfoil created by its movement through the air

Question 35

What is the primary disadvantage of a rigid rotor system?

Answer 35

Flights in turbulence are bumpier due to lack of hinges

Question 36

What are the disadvantages of fully articulated rotor systems?

Answer 36

* High drag * High cost * Complexity * Susceptibility to ground resonance