Model airplane hobby spurs aerodynamics career
Beginning with building balsa wood gliders around age five, Michael Selig’s interest in aerodynamics showed a steady climb throughout his childhood, formal education, and 26-year career as a professor in the Department of Aerospace Engineering at the University of Illinois Urbana-Champaign.
“By age 10, I was into model airplanes in a big way,” Selig said. “As I got older, I flew radio-controlled power planes and gliders. But I had the most interest in gliders. What intrigued me about the gliders was the airfoil, because that’s what makes or breaks a good glider.”
Selig grew up in Lawrenceville, Illinois and earned his bachelor’s degree in 1984 from Illinois.
“I knew I wanted to do aerospace. And this was the place that offered it in Illinois. I didn’t look anywhere else. It was where I wanted to go,” he said.
As an undergrad at Illinois, Selig sought out Mark Maughmer, who earned his B.S. in ’72 and was completing his doctorate in the department when Selig was a senior. Under the direction of Professor Allen Ormsbee, Maughmer conducted aerodynamics research on airfoil design. Selig had learned Maughmer was using the Eppler airfoil design code.
“Mark helped me learn how to run the Eppler Code,” Selig said. “As an undergrad I used it to design quite a few airfoils that I thought would be good for model airplanes. That news spread about my interest in building and flying RC models and my coordinates were published in model aviation magazines.”
Selig has had a long history with AIAA, citing a paper he submitted as a senior at Illinois to the AIAA Regional Student Paper Competition. “The Design of Airfoils at Low Reynolds Numbers” was written with input from Mark Maughmer and Professor Kenneth Sivier. Selig presented the paper at the AIAA 1984 Student Paper Conference, where he won the regional contest. The paper was later published in Soartech 3, which was a publication compiled and edited by Herk Stokely for RC sailplane enthusiasts.
During his senior year at Illinois, Selig applied to graduate schools and accepted a research assistantship offer at Princeton University. Although his master’s work was on supersonic fluid dynamics, he found a way to do low-speed airfoil testing on his own time, along with help from a fellow Princeton student John Donovan.
“I sent out an open letter to many RC modelers asking for airfoil wind tunnel models and in the end, we got about 60 built to our spec,” Selig said. He, along with John Donovan and additional collaborator David Fraser--president and co-founder of Fraser-Volpe--designed and built a test rig to conduct low-speed airfoil experiments at Princeton. They published their findings in the book Airfoils at Low Speeds. The book can still be downloaded from Selig's campus website.
Selig earned his master’s degree in ’88 from Princeton and his doctorate from Penn State in ’92.
“It’s kind of circular that Mark Maughmer was my adviser at Penn State,” Selig said. “As part of my dissertation, I wrote the airfoil design code PROFOIL. I built on the work of Eppler, both in terms of features in the code and also the theoretical development.”
In the fall of ’92, Selig returned to Illinois, this time as an assistant professor. In his new position, Selig continued his airfoil research with minimal interruption. The wind tunnel test section at ILLINOIS is the same size as the one he used at Princeton, enabling him and his students to start out using the same equipment and models from his previous work. Selig's Princeton adviser, Professor Lex Smits, kindly permitted him and fellow student John Donovan to keep all of the original equipment and models used in their Princeton tests.
Recognizing the potential of the World Wide Web in its early days, Selig created a lab website in 1994. The idea to share airfoil coordinates online followed soon after.
“In 1984, I got a lot of mail from people asking for coordinates. I’d print out the coordinates and mail them back to them. Most people still didn’t have email. That went on for a very long time. Being able to finally share the information so people could download it on their own saved me a lot of time.”
Selig launched the online airfoil database, initially populated with the coordinates of the airfoils he had personally collected. Over time, he expanded the database by incorporating additional airfoils from various sources and collaborating with colleagues to include their contributions. It continues to be a popular resource for model airplane enthusiasts, airplane designers, and in academia.
Before that time, coordinates were only available in technical reports, NACA and NASA reports, contractor reports, American Institute of Aeronautics and Astronautics papers, and other scholarly papers.
Julia K. Laystrom-Woodard teaches an AE course at Illinois on computer aided design.
“I share the link to the Selig database of airfoils with the AE 140 CAD students,” she said. “There is an airplane modeling homework problem in the course that uses the database for inputs to generate splines. The splines are then extruded in the CAD software to form wings and tail geometries—the horizontal and vertical stabilizers. I comment to the students about the extensive collection of airfoil shapes that are included in the website database and the helpful gifs that enable easy visualization of the airfoil shapes.”
His campus website also includes the downloadable Summary of Low-Speed Airfoil Data books that document the wind tunnel tests, including the measured airfoil performance data. Selig collaborated with many of his advisees as co-authors on these books.
Selig holds five patents. One with co-inventor, Kyle Wetzel, M.S. ‘93, patents airfoils that have been used on thousands of mega-watt scale wind turbines by GE. Others have been used on radiator cooling fans in semi-trucks, for residential and business ceiling fans, and one involving a method to aerodynamically streamline a wind turbine tower. Another patent is related to morphing wind turbine blade design. The latter two are with co-inventor Eric Loth, a former AE professor who is now at the University of Virginia.
Selig has designed and consulted on a wide variety of aerodynamic applications, including uncrewed aerial vehicles/systems, kilowatt through multi-megawatt scale wind turbines, record-breaking solar-powered aircraft, wing-sail and appendage design for the America's Cup, front and rear wing designs for IndyCars/CART and Formula 1, and many others.
“I worked with the Newman Haas Racing team on their IndyCar wing design,” Selig said. “Airfoils on race cars are flipped upside down so that they produce an aerodynamic downforce to pull them into the ground and increase traction. Working on the America's Cup yacht racing was exciting, too. I went to New Zealand for some of the testing with the Oracle BMW Racing team. Those airfoils are for a keel, something you usually don't see because it is literally a wing under the water. The keel is used to help keep the balance of forces. And it is also used to carry a bulb—a lead mass counterweight so the sailboat won't tip over when sailing.”
Selig also developed an RC flight simulator for airplanes and helicopters. His early collaborators on the project included Brian Fuesz, B.S. ‘83, Chris Lyon, M.S. ‘01, and many others. More recently, Selig worked with Camille Goudeseune, who earned his D.M.A. in ’01 from Illinois, but is also a talented programmer and one of the early developers of Microsoft Word.
The simulator was released in 2006, named FS One, and originally distributed and sold by Horizon Hobby. In 2022, Selig began offering the simulator online for free and the latest version is distributed online as SeligSIM. Since its initial release, the software has attracted tens of thousands of users.
As a professor at Illinois, Selig taught courses in applied aerodynamics and aircraft design. He was instrumental in developing the senior design capstone class, expanding it from one semester to two. The class still uses the annual Request for Proposal from AIAA to define the senior capstone aircraft design final project.
In 2014, Selig received one of the top recognitions from the American Institute of Aeronautics and Astronautics – the AIAA Aerodynamics Award. The award is presented for meritorious achievement in the field of applied aerodynamics, recognizing notable contributions in the development, application, and evaluation of aerodynamic concepts and methods. Selig was chosen “in recognition of outstanding contributions to applied aerodynamics research, design, and education, including leadership in the development and public dissemination of airfoil and propeller data.”
Shape of Flight exhibit combines airfoil history, education, and art
The collection of 48 airfoils mounted on one long wall in Talbot Laboratory on the University of Illinois Urbana-Champaign campus is a museum exhibit, an educational tool, and an art installation all in one. The airfoils make up the new exhibit, Shape of Flight: A legacy of innovation in airfoil design.
The airfoils are all 12” by 33 5/8” test models designed for use on small, low-Reynolds number, or low-speed vehicles such as model aircraft, wind turbine blades, uncrewed aerial vehicles, and more.
Most of the airfoils in the exhibit were tested by Professor Emeritus Michael Selig and his students during his time as an aerospace engineering faculty member at the University of Illinois from 1992 to 2017. However, some were initially tested by Selig and collaborators at Princeton University in the mid to late ‘80s. Among some of his last tests were on airfoils for Google, AeroVironment, and Facebook in support of their solar-powered aircraft projects.
The idea for the exhibit came from Jonathan Freund, professor and head of the Department of Aerospace Engineering. He became aware of the 200-some wind tunnel models tucked away in a loft storage area in one of AE’s wind tunnel buildings and said, “Rather than store them forever where no one will ever see them, let’s do something with them.”
How did these particular 48 from the collection make the final cut for the display? Selig hand-selected them with a variety of criteria in mind.
“I wanted to show a range of airfoil shapes, construction types, surface textures, fabrication techniques, applications, quality, and even colors,” Selig said. “We could have picked a lot more black models but we wanted to have a nice look, too. It’s definitely an exhibit.
“I wanted to include airfoils that represent the project's evolution over time. One of my airfoil designs in the group dates back to 1984 when I was a senior at Illinois with the Eppler code, before having access to wind tunnels and better airfoil design and analysis codes. One of the newest models has an airfoil that was designed and tested for a project sponsored by Google.”
Selig said some models he tested were proprietary, so their coordinates are not published and were not included in the exhibit.
“It's wonderful to see the mosaic of different airfoils," Selig said. "Typically, after a wind tunnel model is tested and the data are published, the model becomes just an artifact. Unlike other sorts of testing, like structural testing to the point of destruction, wind tunnel models usually remain intact and in good condition. They're given away, sold through government surplus, or thrown away. I'm glad we found a way to use them in this display.”
Jason Merret, who teaches aircraft design took the display a step further to make it even more educational. He laser cut profiles of each airfoil to allow visitors to see their aerodynamic characteristics more easily.
Julia Laystrom-Woodard, who teaches an AE course on computer aided design which uses Selig’s online database of airfoil coordinates, said, “I think students really appreciate the concrete visuals provided by the airfoil exhibit. The students have learned about the geometries of wings and it’s great to see those shapes in person. The additional information and the cross sections created by Jason are very helpful to round out the exhibit.”