Martin Müller Designs RC Vehicles that Fly at Appropriately Scaled Speeds

By Terry Dunn

Martin Müller created a scale model of an Airbus A310 airliner that flies at scale speeds.

I'm sure we've all had the experience of watching a huge airliner fly overhead at what appears to be an impossibly slow speed. Most of these jets have to be moving at least 240 kilometers per hour (150 miles per hour) just to get off the ground. Although we certainly realize that they are actually flying quite swiftly, that knowledge doesn't jibe with the tortoise-like pace that our eyes are seeing.

Martin Müller's Airbus A310 model is able to fly at super-slow scale airspeeds thanks in part to its helium-filled fuselage.

We can recreate flying replicas of airplanes in just about any imaginable size and level of detail. Yet, that illusion of speed (or lack thereof) almost never translates well. Most RC models appear to be flying much faster than their full-scale brothers. Martin Müller decided to address that disconnect.

Martin's idea was to create a scale model of an Airbus A310 airliner that would fly at scale speeds. This meant that his 2-meter-span (79 in) Airbus (approximately 1/22-scale) would have a takeoff speed of about 3 meters per second (6.7 mph). Martin knew that creating a model capable of flying at such slow speeds would require an extreme emphasis on shedding weight and more than a little bit of clever thinking.

Müller is no stranger to innovation in the RC world. Around 2003, he developed the Ikarus Shock Flyer, a series of highly aerobatic models made of simple sheet foam with carbon fiber bracing. While the Shock Flyers were meant for indoor aerobatic competitions, they unintentionally spawned a whole new genre of RC models: profile foamies. These types of models can be dreamt, designed, and built in a matter of a few hours. More-traditional balsa designs often require weeks or months to get off the ground. Martin also designed several molded-foam models for Multiplex, including the Park Master, Gemini, and uber-popular Fun Cub.

Müller vacuformed the motor cowlings using lightweight Depron foam.

Weight-saving efforts can be found throughout Müller's Airbus. Custom-molded Depron foam parts and tiny brushless motors are just two examples. The most unique lightweight feature of this model is the fuselage. It is basically a large Mylar balloon in the shape of an airplane body. When filled with helium, the fuselage actually provides 40 grams (1.4 oz) of buoyancy. That's a significant value considering that the flying weight of the entire model is around 300 grams (10.6 oz).

The inflated fuselage has sufficient rigidity that no additional bracing is required. In fact, the right and left wing panels are not even connected to each other with a common spar. They are simply glued to the Mylar with a butt joint.

Despite Müller's drive for a super-lightweight airplane, he still incorporated several functions usually reserved for models with a more accommodating weight budget. His Airbus has retractable landing gear, flaps, lights and wing spoilerons. It is amazing that he was able to fold in so many different scale features in this model.

Despite the feather-like weight of the Airbus, it still incorporates scale features such as retractable landing gear, wing flaps, and wing spoilers.

The Airbus is amazing to see in flight. It flies so slowly that it appears to be defying physics. Müller often flies the model indoors with no problem. When he wants to fly the Airbus outdoors, he trades the helium for air. Yes, that's right…he uses air for ballast with this model!

Martin created the Airbus several years ago. In fact it appeared just a few years after the Shock Flyer's debut. He doubts the practicality of an inflatable model like the Airbus as a mass-produced kit, but it has inspired others to create similar airplanes. His friend Rainer Mugrauer also built a helium-filled Airbus, his an A320 model. Although Mugrauer's Airbus lacks flaps, landing gear, and lights, it is larger and flies even more slowly than Müller's.

Drifting with Realism

One of Müller's current projects is the DR!FT series of 1/43-scale RC cars that are programmed to perform like full-scale cars.

Müller's desire for scale-like performance is not limited to flying models. He is currently involved with developing the Dr!ft line of 1/43-scale RC cars that are meant to emulate the handling of full-scale cars. Most RC cars have features that can be tuned to tweak their acceleration and handling, so that's nothing new. What is unique about Müller's design is that the model's performance is adjusted through a smart-phone app. Without changing tires, gears, shock oil or anything else, you can decide whether your model will handle like a drift car or a race car for any given session. The same app turns your phone into the steering wheel and provides engine sound effects.

Drift recently had a successful Kickstarter campaign and they should begin delivering production units in August of 2017.

Looking Ahead

Müller has collaborated to design a super-lightweight turbine-powered model. Prototypes are being built and should be ready to fly soon.

Müller's interests in RC seem to have no bounds. During our conversation, he told me about a large turbine-powered model he has been flying. The airplane is a scale model of NASA's X-31. Like the full-scale X-31, Martin's rather large model (3 meter [118 in] length, 2 meter [79 in] wingspan) is designed for otherworldly maneuverability using thrust vectoring. And like the Airbus, the X-31 model has an exceptionally lightweight airframe. The results speak for themselves.

The success of the X-31 model encouraged Martin to collaborate with Christian Göbel (builder of the X-31) to design another lightweight turbine model. This model will also be about 3 meters long with a 2 meter wingspan. It is projected to weigh less than 20 kilograms (44 lb). Given Martin's track record with all types of models, I expect it to be a stellar performer. I also look forward to seeing whatever RC creation Müller dreams up next.

Terry is a freelance writer living in Lubbock, Texas. Visit his website at TerryDunn.org and follow him on Twitter and Facebook. You can also hear Terry talk about RC hobbies as one of the hosts of the RC Roundtable podcast.