UIUC Low-Speed Airfoil Tests


Michael Selig, Paul Gush and Kian Tehrani
Department of Aerospace Engineering
University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Last update 11/18/05 what's new
FAQ - Where can I get airfoil data?

In Brief

The goals of this research are to design, analyze and wind tunnel test airfoils for application to model aircraft, unmanned aerial vehicles, small wind turbines, and any other systems that operate in the "low Reynolds number regime" (Re < 500,000). To date over 180 airfoils have been tested and most are documented in the collection: SoarTech 8 and Summary of Low-Speed Airfoil Data - Volumes 1, 2, 3, and 4. Volumes 5 and 6 are currently being written. For more info see the synopsis (a bit out of date). Funding for this research into airfoils at low Reynolds numbers was made possible largely through the support of many generous model aviation enthusiasts. Volume 4, which includes airfoils for application to small wind turbines, was funded by the National Renewable Energy Laboratory, National Wind Technology Center (NREL-NWTC), This "Vol 4" has been packaged as an NREL-NWTC report and it's free (see link below). Tabulated airfoil data from Volumes 1, 2, 3 and 4 are on the web here. The dataset tested are summarized in the tables below: Also, the data from SoarTech 8 and Vols 1-3 can be view using Mike Garton's new airfoil-performance comparison page at http://soaring.cnde.iastate.edu/calcs/frames.shtml (seems to be a broken link). This site makes use of the UIUC LSATs low Reynolds number airfoil data.

All of the Airfoils Tested

Master List: A listing of all the airfoil that have been tested and published in the UIUC LSATs books sorted by Vol and also airfoil name.

Our Books

Newsletters and Most Recent Update

UIUC LSATs Web Articles and Book Announcements

UIUC LSATs Wind Tunnel Model Constructions Notes

Airfoil Performance Data as Published in Our Books

Other Information

The fun...

What we don't see - the laminar separation bubble on the airfoil upper surface that can lead to high airfoil drag if not managed correctly by proper airfoil design or otherwise "repairs" (boundary layer trips).

Smoke flow visualization of a laminar separation bubble on the Eppler 387 airfoil at a chord Reynolds number of 100,000 and 2 deg angle of attack. Only a section of the airfoil is shown. Photo courtesy of Greg Cole and Prof. Mueller, University of Notre Dame.
Larger version (1 MB): NDbub.jpg
If you use this photo, please acknowledge Greg Cole and Prof. Mueller as the source.


Bryan D. McGranahan and Michael S. Selig

Above is the E387 with oil flow viz at a Reynolds number of 350,000 and angle of attack of 2 deg in the UIUC tunnel. We start by spraying an oil mix onto the model (see Vol 3 above for more details). Under a black light the sprayed-on oil has an orange-peel textured look. Once in the tunnel for ~15 mins, the laminar flow smoothly streaks the oil, until point A where laminar separation starts. Beyond this point and inside the bubble, there is very little flow and the oil does not change; it keeps the orange-peel textured look. At reattachment (point B) which is quite unsteady and vigorous, the flow impinges on the surface and creates high shear stress that scours away the oil. It moves some oil upstream and some oil downstream as the downflow "splashes" onto the surface—effectively creating a "continental divide" defined by a very fine dividing line. The oil moving upstream pools into what we call the "oil accumulation line," while the oil going downstream moves towards the trailing edge.

The bubble sketched on the airfoil above the oil-flow image is thicker than in real life for this Reynolds number. Again the flow is unsteady—the bubble not so nicely closed.

Downloads of above image:

If you use any of these materials, please acknowledge Bryan D. McGranahan and Prof Selig as the source.
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