LESSON 2
BASIC AERODYNAMICS
Critical Tasks:
OVERVIEW
LESSON DESCRIPTION:
In this lesson you will learn basic aerodynamics.
TERMINAL LEARNING OBJECTIVE:
ACTION:
You will know basic aerodynamics.
CONDITION:
You will be given the information provided in this text, a list of reference manuals,
and charts provided in the text.
STANDARD:
You will correctly answer all the questions in the practice exercise before you proceed
to the next lesson
REFERENCES: Listed in appendix I.
INTRODUCTION
2.1. GENERAL
Aerodynamics involves the motion of air and other gases and the forces acting on objects in motion
through the air. Put another way, aerodynamics deals with aircraft, wind movement, and atmosphere. A
working understanding of aircraft flight must start with a basic knowledge of flight theory as it pertains
to conventional aircraft.
2.2. BERNOULLI'S THEOREM
At any point in a tube through which a liquid is flowing, the sum of pressure energy, potential
energy, and the energy of motion is constant. This theory was discovered by Daniel Bernoulli, a Swiss
mathematician and physician. How the theory works is illustrated in figure 2.1. An American engineer,
Clemens Herschel, invented the venturi tube and named it in honor of Giovanni Venturi. If the same
amount of air that enters the airflow inlet is to leave the airflow outlet, then the velocity of the air must
increase while passing the venturi throat. As the velocity increases, the air has less time to push against
the sides of the tube, thereby exerting less pressure. Figure 2.1 shows the decrease in pressure gages.
Because there is no change in the velocity of the air about the open end of the tube, there is no change in
pressure. The differential pressure on the ends of the tubes attached to the venturi throat causes the fluid
to move toward the end of the tube that has the least pressure.
2.3. NEWTON'S LAWS
Sir Isaac Newton formulated the three laws of motion upon which classical dynamics are based.
These laws are directly applicable to modern aerodynamics and are discussed in the subparagraphs that
follow.
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