With this computer program
you can investigate how an airplane wing produces
You can change the values of different factors
that determine lift and drag by using the colored buttons located below
the picture of the wing. The value of the lift and drag are presented by the
thermometer gages on the lower right.
FoilSim III is the latest (July 2010) version of the FoilSim family of
Different versions of FoilSim require different amounts of
knowledge of aerodynamics and computer programs.
This web page contains the on-line elementary version of the FoilSim III program.
It includes an on-line user's manual which describes the
various options available in the program and includes links to pages of the
Beginner's Guide to Aerodynamics
describing the math and science of airfoils.
More experienced users can select a
version of the program which does not include
these instructions and loads faster on your computer.
If you would like to learn more about wings and the generation of lift and drag
we suggest you try the
student version of FoilSim.
This version lets you change any of the the flight conditions and
geometry of the wing using sliders and input boxes. You can study different
shaped wings and the forces on cylinders and balls. There are a variety of
output panels including performance plots and pressure and velocity variation on
the surface of the wing.
There are several other simulation programs based on FoilSim.
You can investigate the role of aerodynamics in
pitching a baseball by using
the curve if a soccer ball by using
or wind tunnel testing techniques by using
This program is designed to be interactive, so you have to work with the program.
Input for this simple program is done with button widgets.
To operate a button, move the cursor over the button and
left click with the mouse.
program screen is divided into four main parts:
top left side of the screen is the View Window.
The view window has a picture of the airfoil that you are
designing. Moving particles show the flow past the airfoil.
upper right side of the screen is the Control Panel
with the orange Reset button.
At any time, you can return to the original default conditions,
by clicking the Reset button.
lower left side of the screen is the Input Window.
You can change the value of lift and drag by varying the
speed of the airplane,
the altitude which affects the air density,
the angle of attack of the airfoil,
the camber, which is the curvature of the airfoil,
the thickness, which is defined on the
wing geometry web page,
or the wing area.
The current values of the design variables are presented in boxes located
next to the red and blue buttons. Clicking a blue button dereases the value of
the variable, clicking a red button increases the value.
There are limits on all the variables,
When you hit the maximum limit, the variable won't increase.
When you hit the minimum limit, the variable won't decrease.
lower right side of the screen is the Output Window.
The output is presented as colored gages, or bar graphs, for the lift
and drag. There is a number scale with a colored bar that moves up
and down. The color of the bar changes depending on the value of the lift
or drag. On the left side, we give you the "scale" to the color.
(For example, if the
lift bar is red [x 100] and reaches to the number 4 on the scale, the value is
4 x 100 = 400 pounds.)
This display was chosen to help younger students learn how to read bar
graphs. The student can also gain a sense for how sensitive the lift and drag
are to certain input variables, by noting how far the bar moves. For some
variables, the drag changes a lot and the lift does not change at all!
At the top of the output window we show the numerical value of the lift
and drag. This output can be used to as a source of data for students
to generate graphs by hand.
The NASA Glenn Educational
Programs Office will continue to improve and update FoilSim III based on user input.
Changes from previous versions of the program include:
On 7 Sep 10,
version 1.1c was released. This is the first release version for the
elementary version of FoilSim III and
Earlier elementary versions of FoilSim III
were developmental versions and not released to the public.