Activity 4.2.3 Airfoils, Lift and Bernoulli’s
Principle
Introduction
In the last activity, you learned some of the basic concepts of aerodynamics,
including definitions, Newton’s Laws of Motion, and forces acting on an airplane
during flight.
Daniel Bernoulli, an eighteenth-century Swiss scientist, discovered that as the
velocity of a fluid increases, its pressure decreases. What Bernoulli was able to
show is what is sometimes called Bernoulli’s law of pressure differential for fluids.
Since air is a fluid, this pressure difference is important. During this activity, you will
discover why.
Equipment
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GTT notebook
Pencil
Procedure
Follow along with the presentation on Bernoulli’s principle, answering the following
questions.
1. In order to understand lift, complete the following definitions and label the parts of
the wings in the sketches below. You will need these definitions before
performing an experiment on lift.
© 2011 Project Lead The Way, Inc.
GTT-FS Activity 4.2.3 Airfoils, Lift and Bernoulli’s Principle – Page 1
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Angle of Attack –
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Camber –
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Chord –
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Leading Edge –
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Mean Camber Line –
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Thickness –
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Trailing Edge –
1. Bernoulli’s principle states that:
2. Bernoulli proved that when fluids move _________________, their pressure
____________________. So the air pressure above the wing is _____________
than the air pressure below the wing. Lift occurs because there is ____________
pressure below the wing.
3. Why is air considered a fluid? (What is the definition of the term “fluid”?)
4. List and describe three major factors that affect lift.
5. Airfoil shapes are designed to generate as much ____________ as possible
while incurring as little ______________ as possible.
© 2011 Project Lead The Way, Inc.
GTT-FS Activity 4.2.3 Airfoils, Lift and Bernoulli’s Principle – Page 2
6. Describe the Angle of Incidence.
7. Describe the Angle of Attack
8. Sometimes the air flowing over a wing will get all jumbled up and not flow
smoothly around the airfoil. If this happens, lift will not be generated. Describe
three situations that could cause the airplane to lose lift or stall.
9. List six factors that affect the amount of lift produced by an airfoil.
Follow along and answer the following questions as your teacher proves that Bernoulli’s
principle is valid using the NASA FoilSim website: http://www.grc.nasa.gov/WWW/K12/airplane/foil2.html
General Instructions
1. Click on the Reset button. This will return all settings to default. In the second
box under the Reset button, click on the drop down arrow and select
Shape/Angle for the Input. Change the value for Angle to 0. Be sure to press
Enter.
2. Launch the probe by clicking on the down arrow to the right of Output. Select
Probe.
3. Click on the word Velocity. You should now see the probe. Using the slider bar
under the Velocity gauge, move the probe so that it is on the first wind line
directly under the thickest portion of the airfoil.
4. Record the velocity at that point in the table below. Then click on Pressure and
record the value.
© 2011 Project Lead The Way, Inc.
GTT-FS Activity 4.2.3 Airfoils, Lift and Bernoulli’s Principle – Page 3
5. Move the probe using the vertical slider bar to the left of the Pressure gauge.
Place the probe one wind line above the airfoil. Do not move the probe left or
right.
6. Record the velocity and pressure at that point.
Control
Above the Wing
Below the Wing
Velocity
Pressure
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In this configuration, is there lift? _____________________ If so, how much?
_____________
Why?
7. Change the Camber (wing curvature) to 1.0.
8. Move the probe and record the appropriate data in the data table below.
Camber at 1.0
Above the Wing
Below the Wing
Velocity
Pressure
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In this configuration, is there lift? _____________________ If so, how much?
_____________
Why?
9. Change the Camber back to zero and change the Angle of Attack to 10.
10. Fill in the data table below.
Angle at 10
Above the Wing
Below the Wing
Velocity
Pressure
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In this configuration, is there lift? _____________________ If so, how much?
_____________
Why?
© 2011 Project Lead The Way, Inc.
GTT-FS Activity 4.2.3 Airfoils, Lift and Bernoulli’s Principle – Page 4
11. Leave the Angle of Attack at 10 and change the speed to 150 (change input
mode to flight test).
Angle at 10
Above the Wing
Below the Wing
Speed at 150
Velocity
Pressure
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In this configuration, is there lift? _____________________ If so, how much?
_____________
Why?
Conclusion
1. What is the difference between a wing and an airfoil?
2. What are three major factors that can change the velocity and pressure of air
flow around a wing and thus increase the amount of lift?
3. In your own words, how is lift created with an airfoil?
4. What two scientific laws or principles contribute to the total amount of lift?
5. Based on what you have already learned, do you think any shape will work for an
airfoil? Why or why not?
© 2011 Project Lead The Way, Inc.
GTT-FS Activity 4.2.3 Airfoils, Lift and Bernoulli’s Principle – Page 5