UIUC Low-Speed Airfoil Tests

Wind Tunnel Model Construction Notes (Version 6)

Michael Selig, Rob Deters, and Paul Gush
Department of Aerospace Engineering
University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Last update 10/9/06 modelNotes-versionChanges.html

Important Dimensions

Materials Supplied

General Notes

Special Considerations

Wind Tunnel Model Accuracy

The accuracy of the wind tunnel models cannot be over-emphasized. All airfoils are round in the front and sharp in the back; what separates the good from the bad is what happens in between. The difference in shape between a "good" airfoil and a "better" airfoil is not large. However, since the difference in drag can be quite significant, it makes it worthwhile to be as accurate as possible. Accuracy is important from a different standpoint as well. Extremely accurate lift and drag measurements will be taken in a wind tunnel with excellent flow quality, and each airfoil will require approximately 16 hours of tunnel time to span a range of Reynolds numbers and angles of attack. If the models are of comparable quality, then the measurements are meaningful; otherwise, they are not. To aid in building the most accurate model possible, you will be sent if requested CNC machined female templates of the airfoil contour.

Suggestions for Being Accurate

The most important step involves making the rib templates (or foam core templates). This step should not be rushed. After the model is assembled and ready to be sanded, check the profile with the female templates. Put the female template on the model and shine a light from the other side. If light shines through between the model and the template, the model should be sanded until the template and the model agree. A separate template should be used to check the model leading edge in the same way. If you are aware of inaccuracies with your model, rework the model until it is accurate.

Shipping of Models

Models should be mailed to the following address:

Prof Michael Selig
Dept. of Aerospace Engineering
University of Illinois at Urbana-Champaign
306 Talbot Laboratory, 104 S. Wright St.
Urbana, IL 61801-2935
(217) 244-5757
Finally, if you build a model, we're going to send you a free copy of the next airfoil book. Let us know if your address changes.
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