You never know whom you are standing next to or will meet at an RC event. I met Eddie Saurenman of Saurenman Aero Works (SAW) at Joe Nall Week this year. He is a full-scale pilot, aircraft designer, and a member of The Profile Brotherhood forum, and he had owned a Billy Hell Mojo (an airplane I sold that was designed by Paul Swany).
Eddie is using his RC 3-D and full-scale design background to create one of the most aggressive aerobatic biplanes in the world for Skip Stewart, a well-known aerobatic pilot.
I’ve seen Skip fly, and I could only imagine the demands required for an airplane such as this. I was fascinated to learn how much RC played into the development of this airplane.
Eddie explained how all of his passions were put to the test to create what could be a revolutionary full-scale aerobatic aircraft.
Growing Up Around Airplanes
My parents were pilots. Formula 1 racers and small, aerobatic biplanes captured my imagination. As a kid, I built and flew CL models, starting first with kits.
Designing and building my own models happened at Mach speed. I found my passion. (My daughter, Hanna, age 10, is now building her own CL models and soloed at Oshkosh, Wisconsin, this year on her second flight!)
I began flying lessons at age 10. I soloed at 15 with Jack Lowers at Ball Field in Louisburg, North Carolina, the home of Squadron II, and at 17, I had my pilot’s license and started flying Pitts Specials.
At 18, I earned my Unlimited aerobatic FAA waiver and began flying air shows with Jimmy Franklin, Steve Franklin, Doug Rhinehart, Duane Cole, Chuck Corothers, and other aviation legends. I began constructing my first homebuilt biplane, a Lowers Special, when I was a freshman in high school.
Jack sold me my first airplane: a Pitts S1C biplane. Jack was an ambassador of sport aviation and my childhood hero. He built custom airplanes, raced Formula 1s, biplanes, and T6s at the Reno Air Races in Nevada, and was an exceptional aerobatic pilot. He mentored me—a kid couldn’t ask for a better role model.
A few years later, I was working for a company called Aerotek, in New Mexico. It was operated by George Applebay, who manufactured a composite sailplane called the Zuni. I became friends with air-racing legend Jon Sharp (Nemesis Air Racing Team) who also worked at Aerotek. I introduced him to Formula 1 airplanes and he introduced me to RC.
Learning About RC
Jon sold me my first RC gear: a Royal Classic radio and a Midwest Pitts that he had started. I finished the build. The RC aircraft lasted for roughly a half second—I barely got it off the ground before it tore into pieces!
At that time, electric-powered flat foamies were introduced. My first foamie was a Tensor. It was an interesting airplane with unique handling characteristics. With a little CA and kicker I could quickly get it back into the air after a crash.
George Hicks designed the Tensor and we chatted about foamies and their use in the design process. Reynolds Numbers don’t affect flat foamies because they have low volume (thin plates), and they can be used to help understand the handling characteristics of a design.
Foamies let me experiment with the handling qualities of various configurations at low cost. With a razor blade, foam, and CA, I could land the airplane, make a configuration change, and test it—all in a few minutes.
The Bridge Between Foamies and Full-Scale
Throughout the years, I have made modifications to full-scale airplanes that I owned, as well as for full-scale pilots such as Skip Stewart, Sean D. Tucker, Mike Wiskus, John Klatt, and the late Greg Poe.
Most of these full-scale modifications where done before the advent of electric foamies, so changes to the full-scale aircraft required several iterations to achieve the correct control and maneuverability.
There are several tails hanging on various hangar walls—sacrifices to the “God of Agility.” No equation gets it right the first time. Those who are unwilling to endure the process of improvement seldom succeed.
In between my work in the aerospace industry and modifying full-scale aircraft, I continued to pursue aerobatic airplane design using foamies, particularly biplanes. I built and modified numerous foamies. By testing my designs, I got area moments and aerodynamic center placements to work in concert. My tests with foamies taught me that side-force generators are a crucial part of designing a biplane that requires no control mixing. Size and position are critical.
Designing SAW Revolution: RC and Full-Scale
Skip Stewart is a world-renowned full-scale aerobatic pilot, an RC pilot, and he flies 3-D with foamies and Giant-Scale airplanes. We worked together for several years to improve Prometheus, his highly-modified Pitts S2S. He told me he wanted something new, such as an all-carbon biplane, and asked if that was possible.
My answer was, “Hell yeah, I’ll send you a sketch!” His only demands were that it must be a biplane and it must be obvious that the airframe was composite. I whipped out a pencil sketch that depicted the biplane design that I had refined using foamies and sent it to him. Skip responded, “Let’s do it!”
The foamie was scaled up and full-scale design work began. My years of designing and analyzing aircraft structures in the aerospace business swung into high gear. Skip and I decided that a large-scale RC model would be advantageous.
We contacted Weimo Composites, a European company that specialized in large-scale RC aircraft. Wim Verwoert and John van Gastel of Weimo Composites learned of the Revolution through Skip’s Facebook page.
We made a deal with Weimo Composites and the 40% RC Revolution project began. It is an exact-scale version of the full-scale design, and has an all-carbon-fiber airframe.
Weimo Composites was interested in producing the full-scale aircraft. With Weimo joining the team as manufacturer, the partnership was complete! The two-year program is nearing completion and flight testing for the full-scale Revolution will soon begin.
The prototype 40% Revolution was at Joe Nall Week, and has been flown in Europe. Those who have flown it marvel that no control mixing is required—rare for an RC biplane. The 40% RC version of the Revolution is expected to be sold by Weimo Composites in Europe and Skip Stewart Airshows in the US.
SAW P3 Revolution 40%
Wingspan: 100.79 inches
Length: 95.67 inches
Weight: 54.45 pounds
Engine: 3W212-B4
Mufflers: Custom built by Metallwaren Krumscheid
Electronics: Emcotec DPSI 2018 with Futaba S.Bus
Servos: Eight BLS172HVs and one BLS272HV
To Future Designers
When it comes to designing, think outside of the box. Try new ideas and be creative. Don’t buy into the concept that you need a million dollars and a wind tunnel. There is plenty you can do and learn with RC foamies.
Study past and current designs, then build and fly them. Find out why you like some but not others. Join forums such as RCGroups.com, The Profile Brotherhood, etc.
Study three-views, train yourself to sketch, read books on aircraft design, and don’t let math scare you. Behind every success story is a string of perceived failures. The only real failure is when you give up and quit. Never give up and always expect to win, and remember that this stuff is fun!
