Where are they now? William D. Bertelsen, B.S. '82
William D. Bertelsen
University of Illinois, B.A. ’71 in political science
B.S. ’82 in Aeronautical and Astronautical Engineering
Describe your early education and career experiences.
I earned a B.S. in Aeronautical and Astronautical Engineering from Illinois, 1982. Much earlier, before I finally “found myself”, I received a B.A. from Illinois in Political Science in 1971. I remain proud that I was also men’s intramural Frisbee co-champion that year. In my junior year, I registered for Aviation 101, and subsequently received a single-engine-land private pilot rating from the University of Illinois Institute of Aviation at Willard Airport. I soloed in the #5 Piper Cherokee 140.
After my 1971 graduation, I took on some projects with my inventor dad, William R. Bertelsen, including experiments with ultra-light fabric arc wings. He is best-known for his pioneering work on air cushion vehicles. In the mid-1970s we brought a fabric arc wing model to the Urbana campus for wind tunnel testing with the late Dr. H.S. Stillwell, assisted by the late Professor Kenneth Sivier. Dr. Stillwell was head of the department at that time. Thanks to that experience, I was energized about studying aeronautical engineering at Illinois.
I returned to Urbana in 1979 to study aero engineering full time. Dr. Harry Hilton was my advisor. Because of my liberal arts degree, I was able to focus solely on the technical courses, and so completed my degree in three years.
Professor Sivier was my mentor for a paper study of an arc-wing utility vertical-takeoff-and-landing concept that we submitted for the Bendix Senior Design Competition in 1982. We didn't win, but the paper made a good case for the arc wing as an effective means to generate high lift from a short-span wing.
After the 1982 graduation I went on to a career in composite materials testing at Gougeon Brothers, Inc. (GBI) in Bay City, Michigan. Between 1978 and 1998 Gougeon Brothers designed and built thousands of wind turbine blades, all comprised of laminated Douglas fir and epoxy, many of which are still in service. As Chief Test Engineer, I was principle investigator in several major wood/epoxy-composite fatigue testing programs for the U.S. Department of Energy.
To support the GBI marine epoxy business, I developed a distributed-load test method for sandwich composite panels (ASTM D6416). Beginning in 2002, I served either as chairman or vice chairman of the ASTM D30.09 Subcommittee on Sandwich Construction for the next 10 years. The experience I had in the test lab taught me much about composites, and of course, I was continually on the lookout for aeronautical applications. I retired from GBI in August of 2013.
In 2009, my boss at GBI Robert Monroe and I founded Bertelsen Design LLC to develop arc wing technology. That gave me the opportunity to resume arc wing research with construction of a large powered model with two carbon-fiber arc wing elements and dual-rotating propellers. Using strain gages on the wing spar, we were able to show that the model could convert about 90 percent of the propeller thrust into lift. Then we worked out the mechanics of nesting the two arc wing shells together to reconfigure the airframe for high-speed cruise. I presented our findings at the 2016 International Powered Lift Conference in Hartford, Connecticut.
In March of 2009, my dad and I were awarded U.S. Patent 7,510,143 “Wing Assembly and Aircraft” for a system to stabilize and control an arc wing in pitch. In May of 2017, Bertelsen Design was awarded U.S. Patent 9,637,230 B2 “Aircraft and Convertible Wing Assembly” for a mechanism to consolidate multiple arc wing elements for transition and cruise using an aerodynamic assist.
What are you doing now?
I am working to develop an affordable, high-performance VTOL for general aviation. I envision the prototype to be a two- to four-place aircraft. By “high-performance” I mean fast (300+ knots) and long-range (1,000 miles). I believe an airframe consisting of a multi-element arc wing powered by dual-rotating propellers has the potential to realize these goals. The arc geometry of the wing and flaps enables generation of high lift for vertical takeoff. Then, with flaps retracted, the short span and dual-rotating props drive acceleration to efficient, high-speed cruise. Dual-rotating props on the Russian TU-95 bomber drive it to a cruise speed of nearly 500 mph, with an un-refueled range of 8,000 miles.
As for safety, the arc wing VTOL is relatively simple mechanically, and the presence of the high-lift wing provides a survivability in a complete power loss that other configurations, such as the tilt rotor, cannot provide.
How did your education and experiences at Illinois help you get there?
I have already mentioned the debt I owe to the late H.S. Stillwell and the late Ken Sivier in applied aerodynamics. The faculty prepared me well for what turned out to be dual careers in composites research and aeronautical research. They equipped me with tools that I regularly use. To list just a few specific examples: From Allen Ormsbee I learned how to break down complex problems using dimensional analysis. Thanks to Ken Sivier, I can calculate the static thrust efficiency of propellers. From Professor Balling in TAM I learned the value of free-body diagrams in sorting out results of multiple forces. My introduction to materials science was from metallurgy Professor Marvin Metzger. Elastic modulus and toughness are parameters that I considered nearly every day during my 31 years of materials testing at GBI. The insight that some material properties are time-dependent came from Dr. Harry Hilton.
What’s the coolest thing you’ve done since graduating from Illinois?
To assess the flying qualities of the radical arc wing system in cruise configuration we built a small electric-powered model with a single fiberglass wing, span 24”. With help from the Midland, Michigan R/C Club, the six-pound model demonstrated short takeoff and speed during several five-minute flight. I presented these results in a paper for Forum 74 of the Vertical Flight Society in Phoenix, Arizona in May of last year. Video excerpts of the flights are online.
What advice do you have for current Illinois aerospace students?
It can take time to find the right path to the future. As a very late bloomer, I was fortunate that Dr. Stillwell assured me that it’s never too late to study engineering. I took his advice and re-enrolled at age 30.
It’s okay to try courses from many different disciplines to see where your strengths lie. Because you have been admitted to the University of Illinois in engineering, you have already demonstrated potential. Just keep in mind that you may have potential in more than one area, perhaps one you have yet to discover.
Looking ahead to when your career has been launched, don’t give up if your contributions and innovations are not immediately accepted. A quick check of history reveals so many cases where forward thinkers were initially scoffed at, but who turned out to be right in the long run. Stick to your convictions.