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UIUC LSATs - Wind Tunnel Model NotesUIUC LSATs - Wind Tunnel Model Notes

The low Reynolds number UIUC wind tunnel model construction notes are described below.
If you are asked to build a model for us, these are the notes to follow.

Important Dimensions

Materials Supplied

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 inbetween. 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.

All wind tunnel models are measured using a CMM (coordinate measuring machine) to check their accurate. We post-process the CMM data to make a plot of the model coordinates overlaid with the true airfoil coordinates. The process of making the overlay involves using a least-squares (best) fit between the model airfoil coordinates and true airfoil coordinates. Examples of these kinds of plots are found in our books of airfoil data. Here is an example:

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.

General Notes

Special Considerations

Shipping of Models