Peer Review

FoilSim II version 1.5a

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Reviewed:: Feb 6, 2006 by Engineering

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Ratings

Overall Rating:

Content Quality:

Effectiveness:

Ease of Use:

Overview:: FoilSim,developed by NASA, computes the theoretical lift of a variety of airfoil
shapes. The user can control the shape, size, and inclination of the airfoil
and the atmospheric conditions in which the airfoil is flying. The program
includes a stall model for the airfoil, a model of the Martian atmosphere, and
the ability to specify a variety of fluids for lift comparisons. The program has
graphical and numerical output, including an interactive probe which you can
use to investigate the details of flow around an airfoil.

Different versions exist from an Elementary version for K-6 and an Undergraduate
version for college students.
Type of Material:: Simulation employing a JAVA applet, which can be downloaded and run offline.
Recommended Uses:: As a classroom demonstration or as the basis for a homework assignment.
Technical Requirements:: Browser capable of supporting JAVA. Successfully tested using IE 6.0, Netscape
7.1, Opera 7.0, and Firefox 1.0 browsers.
Identify Major Learning Goals:: In an effort to foster hands-on, inquiry-based learning in science and math, the
NASA Glenn Research Center has developed a series of interactive computer
programs for students that includes FoilSim. The major learning goal is to
investigate how an aircraft wing produces lift by changing the values of
different variable that affect lift.
Target Student Population:: Primarily high school and college students exploring aeronautics in general and
wing theory in particular. However, a simpler version of the program exists for
students in elementary school who are just beginning to learn about wings and
airfoils.
Prerequisite Knowledge or Skills:: There are several versions of FoilSim which require different levels
of experience with the package, knowledge of aerodynamics, and computer
technology. The software web page contains the on-line student version of the
program. It includes an on-line user's manual which describes the various
options available in the program and includes hyperlinks to pages in 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.

Content Quality

Rating:
Strengths:: The Airfoil Simulator, FoilSim, presents valid concepts and models the
performance of a "Joukowski" airfoil quite well. It allows the user to explore
many factors that affect airfoil performance such as the shape, size, and flight
regime of the airfoil.

FoilSim uses easily recognized interactive features such as sliders and
pull-down menus to select different parameters to change such as Test
conditions. The default mode is based on ideal flow, and the software allows
great variability in the range of parameters that can be investigated that
influence flight characteristics of an airfoil. A user can also easily extract
numerical data about the geometry of the airfoil and flow characteristics around
the foil.

The instructions are provided in an easy to follow manner which helps the user
get started quickly. The graphical 2-D flow visualization from the side provides
users with clear sense of the flow around an airfoil.
Concerns:: The plot feature does not work in the stall mode where the boundary layer
separates. However, pressure and velocity data are available through the output
mode 'performance', although it is not clear whether these values are valid.
Rather, it seems the stall model provides the limiting case to illustrate the
effect of stalling. For the pull-down menu for Lift, the user can also select
CL, the coefficient of lift. It would be helpful to new users to state fully
Coefficient of Lift in this drop down menu.

Also, an inadvertent mouse click can cause the graphical view of the airfoil to
wander off the page. Although the author seems to have intended this type of
interaction with the graphical view by allowing the user to move the airfoil
around, it is more of a distraction than a useful feature. Also, the 3-D view
and top view do not seem to add significantly to one's understanding of the
flow structure since the simulation is based on 2-D flow models.

Potential Effectiveness as a Teaching Tool

Rating:
Strengths:: With its excellent graphics, intuitive user interface, and a wide variety of
input and output choices, this learning object has outstanding potential
effectiveness as a teaching and learning tool. It is well suited for classroom
demonstrations, but lends itself equally as a tool to be employed in a
parametric-study type of homework assignment.

FoilSim would easily compliment any course concerned with the flow of a fluid
around a body. The graphics feature and plot feature allow an instructor to
demonstrate visually and quantitatively how changes in the shape, flow and
environment affect lift. This tool would be especially useful in course that
deals with inviscid flows.

It has an excellent set of user instructions and provides hyperlinks to the many
terms that arise in the discussion of airfoils and aircraft. The simulated
probes for flow velocity and pressure make it possible for virtual experiments
to be performed on the airfoil.
Concerns:: Although not a major concern, a nice feature for the probes would be a display
of the x-y coordinates of the probe at any time. This would permit a
quantitative exploration of the flow field. Currently the probes follow a given
streamline when they are moved in the x-direction.

Also, the 3-D plots and top view plots are a bit misleading as this is clearly
based on a 2-D model.

Ease of Use for Both Students and Faculty

Rating:
Strengths:: The airfoil simulator is both convenient and inviting to use. The user interface
screen is divided into four sections: View Window, Control Panel, Output
Window, and Input Window. The layout of the screen is consistent and intuitive.

The View Window presents the airfoil in either an edge view or a side 3-D view.
Streamlines or streaklines can be displayed as well as a number of geometric
terms (e.g. chord) pertinent to airfoils.

The Control Panel allows various choices for the input and output windows. For
example, if "Shape/Angle" or "Size" are selected for Input, the user may
then enter geometric information for the airfoil in the Input Window. But, if
"Flight Test" is chosen, then flight speed and altitude become the input
variables. By choosing then various selections in sequence, the user may
prescribe a given airfoil under a given set of flight conditions.

Likewise, a number of choices are available for the Output Window. These include
plots of pressure and velocity on the upper and lower wing surfaces, plots of
lift versus airspeed, velocity and pressure probes, a smoke generator, and a
lift meter.

Once any of the input variables are changed, the effects on the lift and other
parameters are immediately obvious.

The applet is easily accessible and portable when downloaded. The use of slider
and pull-down menus simplifies the interaction. The online instructions are
thorough and seem clear. Students unfamiliar with aerodynamics are pointed to
reference to help them through the technical details
Concerns:: The user has to take some time to search for different features though the
pull-down menu. It is not immediately clear how to access all the features and
parameters. Again, the user has to be mindful to not pull the graphical view
out of the field of view, and rescale the plots after each subsequent change.

Other Issues and Comments:: Overall this a fairly user friendly tool with many useful features, although
the user must be willing to look for them through the drop down menus. FoilSim
would compliment any course concerned with the concept of lift due to external
flows over bodies.
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