Author: Dave Garwood
Edition: Model Aviation - 2012/08
Page Numbers: 107,108,109
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Guest columnist Steve Lange explains UltraBatics

by Dave Garwood [email protected]

Steve “Surfimp” Lange is a leader and developer in ultralight Slope Aerobatics flying. I had the good fortune of flying with him at the WeaselFest in April 2012 in Santa Barbara, California, and saw some fantastic maneuvers made possible by a new breed of light and durable slope gliders, plus a great deal of pilot skill honed by practice. Here is Steve’s guest column on Ultra-Batics design and flight.

What are ultralight aerobatic gliders?

One of the most exciting new developments in Slope Aerobatics—a part of the hobby that’s made an amazing comeback in recent years—has been the development of ultralight aerobatic gliders. These are fully aerobatic designs constructed from EPP foam with 1.5-meter to 2.5-meter (60-inch to 100-inch) wingspans and tremendously reduced flying weights compared to older designs. A typical 1.5-meter ultralight weighs 16 to 22 ounces ready to fly—less than half the usual weight for this type of design. With a wing loading in the 4 to 6 ounce-per-square-foot range, these airplanes fly with full aerobatic performance in as little as 6 to 8 mph winds at an average slope, and can take full advantage of any available thermal lift.

These gliders use advanced airfoils with always-on dynamic camber changing (provided via radio mixing) to give them identical performance whether upright or inverted. They also have effective rudders and enough side area to perform knife-edge maneuvers, slow and point rolls. Some of the gliders employ radical full-flying stabilizers and rudders capable of 180° rotation that allow the airplane to flip around its CG, much like a jet with thrust vectoring.

Construction and durability

Their low weight, combined with EPP and laminating film construction, makes them nearly indestructible—often more so than a typical EPP airplane. By combining ultramaneuverability with low weight and durability, these gliders let pilots fly radical, unlimited aerobatics almost anywhere, in conditions under which a traditional aerobatics glider couldn’t fly.

While EPP construction and laminating film covering are well known in the Slope Soaring world, they previously were used mainly in heavy-duty applications for combat wings and dynamic soaring. The way they’ve been combined in these ultralight aerobats is novel.

Pioneers and design evolution

These techniques were pioneered in Santa Barbara by Peter Richner. He’s been heavily involved in RC flying since he was a child in Switzerland and has tremendous passion and motivation to bring innovation to the hobby. Drawing on his experience flying powered 3-D airplanes, and deeply inspired by the Dream-Flight Alula, Peter tried to see if he could unlock new possibilities for Slope Aerobatics by pursuing an ultralight wing loading.

Using my Le Fish and Spindrift designs as a basis, Peter built a series of prototypes to successively lower weights, ultimately producing a Spindrift with a ready-to-fly weight of only 13.7 ounces—completely unheard of for a 1.5-meter (60-inch) EPP aerobatics glider!

Thanks to Peter’s innovation, I finally realized my original vision for the Le Fish—an aerobatics glider I designed in 2005 with inspiration from the French Slope Aerobatics scene.

The Le Fish story

The primary goal of the Le Fish was a lively, fully aerobatic three-axes (aileron/elevator/rudder) glider that could fly in the same type of light lift as a Dream-Flight Weasel and withstand the same kind of abuse. The Le Fish has become a commercial success since its release in 2006, and is now flown throughout the world.

The flying weight of a Le Fish built following traditional methods is roughly 38 to 42 ounces, with a wing loading of 10 to 13 ounces per square foot. While this produces a fun, durable, and capable glider, it can’t fly in very light lift and requires approximately 10 to 12 mph to come alive.

Following Peter’s techniques, I built a Le Fish to a flying weight of 16.5 ounces and discovered, as Peter had, that the airplane flew beautifully in very light lift and opened up an entirely new flying envelope.

Flying characteristics and new maneuvers

Not only could we now fly aerobatics in super-light "Weasel" lift, but we found that the low weight of the airplanes made stalls gentle, allowing recovery in half of a fuselage length or less. This allowed us to fly lower and with greater control. Inverted fin and wingtip drags became easier to perform.

By adding a Madslide-inspired full-flying stabilizer with 180° rotation on my airplane, I was able to perform radical flip maneuvers at eye level—just a few feet in front of me—as I transferred from one mini-bowl in the slope face to another. This was new, and this was fun!

I could finally enjoy the best of both worlds: a glider that was as agile and light in the air as a Weasel or Alula (airplanes that I've loved flying for years), but with the added capabilities that a fully aerobatic glider of conventional planform provides. I found a new realm of creativity before me.

I could blast up out of one bowl, snap roll to inverted, and drag my fin in the grass as I dropped into another bowl. We could fly two airplanes at once within the bounds of a tiny crevice barely 25 feet across, and treat it like a skateboard half-pipe—pumping up each side to keep our momentum going and flying radical aerobatics nonstop, sometimes bumping each other's airplanes with no damage and no crash when impacts occurred.

The durability of the glider meant that I could repeatedly try tricks. The airplane simply soaked up abuse that, based on previous experience, would have snapped tails and broken fuselages had I done them with something heavier. I could fly extremely close to myself, within inches of my face if I wanted, with complete control and confidence. The overall experience was liberating. It was everything I loved about flying a Weasel or Alula, but taken to a new level of involvement and excitement.

The glider had become my brush, the slope face my canvas. I was limited only by my imagination.

Community reaction and sharing

Videos of our flying quickly attracted the attention of the worldwide Slope Aerobatics community, including being featured on the homepages of Pierre Rondel's Planet-Soaring.com and Laurent Berlivet's Jivaro-Models.org in France. The flying weights of our gliders elicited comments and wonder, and we documented the construction techniques in detail via the "How to Build a Swiss Fish" thread in the Slope forum of RCGroups.com.

By putting all information in the public domain, including the plan for the ultra-lightweight Le Fish on SlopeAerobatics.com, the hope was that others would get involved and help push these ideas forward. We didn't have to wait long for that to happen!

Innovations from other pilots and manufacturers

One early innovation came from Dawson Henderson, one of the best-known American Slope Aerobatics pilots. He devised a pulley control system to address challenges inherent to the Madslide-style 180° rotation elevator. Using his own ultralight Le Fish, he was the first pilot to successfully replicate the multiple flips shown in the original Madslide video of Benoit Paysant-Le Roux (aka BPLR), the French designer who invented this stabilizer arrangement back in 2000 for his Madslide. BPLR saw the videos, was impressed, and extended his congratulations to Dawson and encouragement to our efforts.

Pilots around the world began trying their own interpretations of the ultralight EPP aerobat philosophy. In southern California, John Scahill collaborated with Dan McCleary of Xtreme Gliders on a number of designs, including a Power Scale Soaring (PSS) Extra with Madslide-style stabilizer and a neat Shark glider that looks like an actual shark and does cool, flat spins.

Paige Anderson of Future Slope Designs is marketing the Flow, intending to exploit the capabilities of these ultralight aerobats that perform virtually endless aerobatic sequences. Leading Edge Gliders also offers ultralight versions of the Le Fish and Spindrift that incorporate all of these enhancements.

Looking forward

It's been an exciting time, and the future is wide open. Peter is already working on his next project, a 4-meter (160-inch) ultralight aerobat that will surely make headlines as one of the largest EPP aircraft ever flown.

I am looking for more ways to adapt my background in skateboarding, surfing, and snowboarding to this type of aerobatics. Dawson continues to inspire the world with his smooth flying and beautiful videos that express the artistic potential of what we've begun calling "Ultra-Batics." These ultralight aerobats have shown us that anything is possible, and the only limitations are those we place on ourselves.

Author's Note

There's no better or easier introduction to what ultralight flying is about than a Dream-Flight Alula or Dream-Flight Weasel. The lightweight philosophy they embody, and the exciting style of highly aerobatic "in your face" flying they encourage, is the core inspiration that has driven this journey for Peter, Dawson, and me.

The ultralight three-axes aerobats extend the fun by offering additional possibilities, but the Dream-Flight airplanes are a perfect starting point. Because the Weasel and Alula airframes are molded from EPO foam, you can have one in the air and begin your exploration of close-in Slope Aerobatics with much less time, effort, and cost than any other option.

—Steve Lange

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Transcribed from original scans by AI. Minor OCR errors may remain.