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Airfoil Data
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Disclaimer

Users of this site must accept this disclaimer of warranty:

The author disclaims all warranties, expressed or implied, including, without limitation, the warranties of merchantability and of fitness for any purpose. The author assumes no liability for damages, direct or consequential, which may result from the use of data from this web site.

Airfoil Data

The airfoil coordinate data has been obtained from the Soartech data disk, an NACA airfoil coordinate generator and the UIUC Airfoil Coordinate Database.

Soartech

The data obtained from the Soartech data disk is copyright by Michael S. Selig, James J. Guglielmo, Andy P. Broeren, and Philippe Giguere. 1995 All rights reserved.

This data was originally compiled at the Princeton University and is now being compiled at the University of Illinois at Urbana-Champaign (UIUC).

UIUC Low-Speed Airfoil Tests Manifesto

We are searching for a group of experienced modelers to build a variety of airfoil wind-tunnel models for tests at the University of Illinois at Urbana-Champaign (UIUC). A low-speed, low-turbulence wind tunnel has been instrumented to take lift and drag measurements on airfoils at low speeds over the Reynolds number range from 40,000 to 500,000 (40k to 500k). The scope of the airfoil wind-tunnel tests will be limited only by the number of wind-tunnel models provided and the amount of funding received. Hopefully, the proposed modeller-supported airfoil test program will become self-sustaining. Your support and help of any kind will be acknowledged in reports on the project to be published through SoarTech Publications (Herk Stokely). We plan to publish the results through SoarTech frequently - possibly twice per year.

A similar undertaking (with substantial support from modellers) was started by Michael Selig, John Donovan and the late David Fraser in 1987 at Princeton University. In a two year period, over 60 various low-speed airfoils were wind-tunnel tested, involving over 1200 hours of wind-tunnel test time. The results were published in SoarTech 8 in 1989, and many of the new airfoil designs produced and tested during the program are now widely used on R/C sailplanes. As of November 1993, over 2200 copies of SoarTech 8 are in circulation worldwide. SoarTech 8 is available from

SoarTech Publications
c/o Herk Stokely
1504 N. Horseshoe Circle
Virginia Beach, VA 23451

email herkstok@aol.com

At the present time, there is a need for new airfoils for R/C sailplanes. For example, R/C handlaunch soaring is booming, but few good airfoils (e.g., E387 and SD7037) presently exist for such sailplanes. Sailplanes for the new F3J competition are just beginning to evolve, and new airfoils will probably be required. What will they look like? In the past, only a few airfoils (e.g., HQ 1.5/8.5, RG15 and SD7003) have been favored for F3B competition. In shape, handling and performance the SD7003 is quite different from the other airfoils mentioned. These significant differences suggest that it may be possible to design new airfoils that have better overall characteristics for F3B competition. In addition to the design and wind-tunnel testing of new airfoils, several existing airfoils should be tested. The SD7037 and RG15 are quite popular and often used with flaps. The flap effectiveness of these airfoils should be quantified through wind-tunnel tests, and the results should be used in the design of new airfoils.

There is also a need for new airfoils for R/C sport, aerobatic, and electric planes, as well as R/C helicopters. Often, NACA airfoils are used for these applications, but as compared with airfoils that could be designed today, many of the NACA airfoils (which were designed decades ago mostly by trial and error) are inferior. At the time the NACA airfoils were designed, little was known about the complex aerodynamics of airfoils operating at low Reynolds numbers. (Airfoils with small chords at low speeds, such as those on model aircraft, are said to operate in the low Reynolds number flight regime). In recent years, much has been learned about low Reynolds number aerodynamics, and this knowledge has successfully been applied to the design of new airfoils for R/C sailplanes, ushering in a new era in R/C soaring. Overall, R/C sailplane performance has improved dramatically. Older airfoils are no longer used. R/C power aircraft performance could likewise be dramatically improved through the use of newly designed, specially tailored airfoils.

Unique airfoil design requirements also exist for other categories of model aircraft. For example, FAI free flight aircraft (which incorporate both a powered launch segment and gliding flight) operate over a wide range of speeds. In the past, many airfoils with good performance characteristics have been designed for FAI free flight. These airfoils should be wind-tunnel tested to quantify their performance. The results gleaned from the tests could then be applied in the design process in an effort to develop new airfoils with improved performance. Also, the Society of Automotive Engineers (SAE) sponsors an annual model airplane design competition in which university student teams design, build and fly an R/C cargo aircraft. The record cargo weight that has been carried now stands at 24 3/4 lb for a model with a 60-size engine and 1200 in^2 total projected area. Conceivably, this record could be broken by an aircraft with an airfoil (or airfoils) specifically designed for the competition. Clearly, the need for new airfoils and data on existing airfoils is not limited just to R/C sailplanes, but applies to any type of model aircraft where better handling qualities and overall performance are desired.

Other topics of interest include the effects of turbulators and contour accuracy. Are boundary layer trips simply "repairs" to otherwise bad airfoils, or can trips be integrated with the airfoil and result in improvements over, say, the SD7037? The Princeton tests began to address this issue, but many questions still remain. For example, what is the best trip height for a given airfoil? Also, what is the best trip geometry, where should the trip be located for best performance, and what type of airfoils respond best to trips? The Princeton tests also shed some light on how accurate airfoils must be in order to achieve expected performance, but a more systematic effort should be made to test the best airfoils for sensitivity to contour accuracy. Also, we are interested in designing and testing families of airfoils for use in, say, transitioning from one airfoil at the root to a different airfoil at the tip. It is unlikely that the best performance can be obtained from a single airfoil used along the entire wing span. This is especially true for flying wings. Companion airfoils for blending should be designed for use with the most popular existing airfoils, e.g., SD7037 and RG15. It is expected that the practice of blending airfoils along the span will become much more popular than it is today. In an effort to maximize low Reynolds number airfoil performance for model aircraft, all of these topics should be addressed.

Overall, the UIUC test objectives will be to design and wind-tunnel test new airfoils for each category of aircraft listed above and also to examine the effects of flaps, turbulators and contour accuracy. We are especially interested in testing existing airfoils that are known to have superior performance. Wind-tunnel data on such airfoils will be used during the design of new and better airfoils. If you believe that we have overlooked an important area, we would be interested in your input and may consider expanding the scope of the project. The number of airfoil models to be tested has not been predefined; rather, it will be depend on the level of interest and support from the modeling community.

The wind-tunnel models should have a 33 5/8 in span with a 12 in chord and can either be built-up or foam core. To insure a uniform contour, the built-up models need to be fully sheeted. For the foam core models, we may be able to supply two 12 inch chord wing templates. The surface finish can either be fibreglass or monokote; however, we are interested in the effects of surface finish and will consider testing models with non-smooth surfaces. The models will be attached to the wind-tunnel balance by standard model wing rods. Standard model construction techniques should provide the necessary strength (supporting 15-20 lb of lift when pinned at both ends). The brass tubing and collars for the models will be supplied along with full-scale plots and/or coordinates of the airfoil, if requested. (Please contact us before starting any construction on a wind-tunnel model.)

The airfoils will be tested in the UIUC open-circuit 3x4 ft subsonic wind tunnel. The turbulence intensity level is minimal and more than sufficient to ensure good flow integrity at low Reynolds numbers. The experimental apparatus used at Princeton will be modified for the UIUC tests. Lift and drag measurements for each airfoil will be taken at Reynolds numbers of 60k, 100k, 200k and 300k. In some instances, it may be possible to take limited data over an expanded range (40k-500k). The lift characteristics will be determined through force-balance measurements, while the drag will be evaluated by the momentum method through the use of pitot-static probes traversed through the airfoil wake at several spanwise locations. We are also interested in airfoil pitching moment measurements, but the current apparatus does not have such a capability. However, a pitching moment balance has been recently designed and should provide pitching moment data in the near future.

If you are interested in building wind-tunnel models for the tests or wish to request information, please write, fax or send e-mail to the coordinator.

UIUC LSATs Coordinator
c/o Prof. Michael Selig
Dept. of Aeronautical and Astronautical Engineering
University of Illinois at Urbana-Champaign
306 Talbot Laboratory 104 S. Wright St.
Urbana, IL 61801-2935

email uiuclsat@opus.aae.uiuc.edu
fax: (217) 244-0720

The program will be self-sustaining so long as funds are made available for equipment maintenance/upgrades and graduate student stipend support and tuition and fees (approximately $16,000/yr per student). The initial goal is to raise enough money to support at least two graduate students for a three year period. It is envisioned that a small level of support from a large number of modeling enthusiasts could sustain the airfoil design wind-tunnel test program indefinitely. The impact on model aviation could be tremendous.

Donations can be mailed to

Prof. Michael Selig
Dept. of Aeronautical and Astronautical Engineering
University of Illinois at Urbana-Champaign
306 Talbot Laboratory 104 S. Wright St.
Urbana, IL 61801-2935

email; m-selig@uiuc.edu

Please make checks payable to "University of Illinois, AAE Dept." Also, please write on the check "Selig - Wind Tunnel Testing/AAE Unrestricted Funds," and provide a letter stating that your contribution is to be used by Prof. Selig and his group of students (both undergraduate and graduate) in support of the airfoil wind-tunnel tests. Finally, for a suggested donation of $18 in US, Canada, and Mexico (or $22 in other countries) you can receive a UIUC LSATs white short-sleeve shirt. All proceeds will go toward the continuation of the project.

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