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Ground School

Chapter 1

QuestionAnswer
Which force produced by the wings support the airplane in flights? Lift.
Which force is produced by the engine propeller? Thrust.
Which force resists the motion of the airplane through the air? Drag.
Lift and weight are generally how much greater than thrust and drag in straight and level flight at a constant airspeed? 10 times.
What relationships exist between lift and weight, and between thrust and drag, when the airplane is flying straight and level at a constant airspeed? Lift = weight; thrust = drag.
Which surface is designed to create an aerodynamic lifting force as air flows over it? An airfoil.
What do you call a steady airflow around an airfoil in which succeeding parcels of air follow each other? Streamline flow.
Where on an airfoil does the smooth boundary-layer flow separate from the airfoil surface and become turbulent? At the separation point.
Static pressure in the air is exerted in which direction(s)? Static pressure in the air is exerted in all directions.
Which pressure is caused by motion? Dynamic pressure.
What is the total pressure energy the sum of? Static pressure + dynamic pressure.
In streamline flow, if dynamic pressure increases, what happens to the static pressure It will decrease.
What does the expression "1/2pV^2" represent? Dynamic pressure.
What line is drawn half-way between the upper and lower surfaces of the wing to give an indication of its curvature? The mean camber line.
The wing shape and the angle of attack determine the profile that the airfoil presents to the airflow. What else do they determine? The lifting ability of the wing.
True/False: The forces acting on an airfoil in flight, as a result of the changes in static pressure around it, may be considered to act through the center of pressure. True.
Describe how the relative airflow relates to the flight path of an airplane. Relative airflow is parallel to the flight path of the airplane and flows in the opposite direction.
Define the term "angle of attack." The angle between the wing chord line and the relative airflow.
If the angle of attack is gradually increased in normal cruise flight, what will happen to the lifting ability of the wing? It will increase.
On a wing, the force of lift acts perpendicular to and the force of drag acts parallel to the : a. chord line b. flight path c. longitudinal axis Answer b.
What does the angle of attack of a wing control directly? Distribution of positive and negative pressure on the wing.
What happens to the center of pressure as the angle of attack is gradually increased in the normal flight range? It moves forward on the wing.
True/False: Beyond the stall angel of attack, the lifting ability of the wing decreases significantly and the center of pressure moves rearward on the wing. True.
How will frost on the wings of an airplane affect takeoff performance? Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting ability.
What is drag? Drag is the component of relative airflow which is parallel to the relative airflow.
True/False: If drag can be kept low, thrust can be kept low. True.
Describe the two basic groups of total drag. The two basic groups of drag are induced drag, which comes about in the production of lift, and parasite drag which is not associated with the production of lift.
True/False: As airspeed increases, drag caused by skin friction decreases. False. As airspeed increases, drag caused by skin friction increases.
How can form drag be reduced? To reduce form drag, separation of the boundary layer airflow from the wing surface should be delayed by streamlining.
True/False: The spanwise flow of air on the upper wing surface is toward the wing root. True.
When is the formation of wingtip vortices and induced drag greatest? At high angles of attack and low airspeeds.
When is the total drag at a minimum? At medium speed where the parasite drag and induced drag are equal.
Why is the thrust requirement greater at high speeds and low angles of attack? Because of the greater parasite drag.
True/False: Minimum drag means minimum thrust to maintain airspeed. True.
What does the lift/drag ratio describe? The lift/drag ratio describes the aerodynamic efficiency of the wing.
What effect does extending the flaps have on the camber of the wing? It increases the camber of the wing.
Aside from lift, what do trailing-edge flaps increase? Drag.
The percentage increase in drag usually exceeds that in lift when the flaps are extended. Do flaps therefore increase the "lift/drag ratio?" No, flaps decrease the lift/drag ratio.
True/False: The extension of flaps on a glide approach allows a steeper approach path at a constant speed. True.
True/False: With flaps extended, the nose attitude of the airplane is higher. False. With flaps extended, the nose attitude of the airplane is lower.
True/False: Slots increase the angle of attack at which the wing stalls by delaying the separation of the smooth airflow over the upper surface of the wing. True.
What does a propeller convert engine torque into? Thrust.
True/False: At high altitudes, when the air is less dense, a propeller will be more efficient. False. At high altitudes, when the air is less dense, a propeller will be less efficient.
Why is a propeller blade twisted? To ensure that it operates at its most efficient angle of attack along is full length.
True/False: A fixed-pitch propeller is efficient at only one set of RPM and airspeed conditions. True.
True/False: A constant-speed propeller has a variable pitch angle and is efficient over a wide range of RPM and airspeed conditions. True.
As the FWD speed of a plane w/ a fixed-pitch prop increases, w/ the RPM remaining constant, the AOA of the propeller blades: a. decreases as forward speed increases b. increases as forward speed increases c. remains unaltered as forward speed increases Answer a.
In an airplane with a clockwise rotating propeller, what does P-factor, or asymmetric blade effect cause the airplane to do? P-factor causes the airplane to yaw left at high angles of attack of the wing.
During the takeoff roll in a single-engine airplane, the left tire will carry more load. Why? Because of the propeller torque reaction.
When is torque effect greatest in a single-engine airplane? Torque effect is greatest in a single-engine airplane at high power and low airspeed.
How can you keep the airplane tracking straight down the runway during the takeoff roll in a single-engine airplane? By applying right rudder.
Created by: pwbandy