Up, up, and away – Big Gliders – Small Engines

I fondly remember the old days when the first large-scale glider models appeared—it must have been between 1975 and 1985—and a real community began to form, such as the IGG, founded in 1982 by Peter Äberli and Georg Staub. Beautiful models by Ernst Tscheulin, and later by Christian Gierke and others, took the gliding world by storm. Tscheulin’s models and others were available as kits with fiberglass fuselages and Styrofoam-Abachi wings. Others purchased only the fuselages and built the wings themselves—a labor-intensive and demanding task. This technique is still used today, refined by a few specialists. Covering the wings with the films available back then was a challenge and caused me to utter numerous curses. Most of our flying sites had only slight elevations. In addition, we had to clear trees and bushes to take advantage of the slope-generated updrafts. High-altitude launches and motorized winches helped us do this.

But suddenly everything changed: Starting in 1973, we held the first electric aircraft air shows in Pfäffikon. The air shows associated with these events increasingly took on the character of a “product showcase,” where more powerful electric motors (by Fritz Geist and Heinz Keller) were soon put to use. Suddenly, ground launches with aerobatic models were possible (Heinz Elsässer) and—this surprised us in particular—Ernst Tscheulin’s demonstrations with his large gliders (Glasflügel 604, Kestrel, LS 2). A few steps for a hand launch, and his 5-meter model soared leisurely into the sky. That broke the spell. Without further ado, the noses were brutally sawed off the beautiful fuselages of our models, and starting around 1980, a “Keller 80 or 100” was installed. Initially, we used nickel-cadmium cells (NiCad, banned since 2006) and later nickel-metal hydride (NiMH) cells. The packs, containing up to 20 cells, quickly added 1 kg or more to the payload. This was no problem for the large gliders (about 3.5 to 5 m). At times, we had half a dozen or more of these elegant and virtually silent gliders in the air.

One beautiful Sunday (around 1980), guests from Lake Zurich arrived at our slope-soaring site with their beautiful large-scale glider models. Before long, heated discussions broke out over our barbarically sawed-off fuselage noses. The enthusiasts of beautiful glider “orchids” were more or less appalled—though this did nothing to dampen our friendship. Over drinks later on, we learned that in the large-scale glider scene, aesthetics—even to this day, by the way—are highly valued, whereas for us, trouble-free launches on a somewhat challenging terrain were the priority. For the larger and heavier models, however, the hand launch became a challenge. Here, too, the “Seebuben” offered us development assistance with their catapult.

For several years now, large gliders equipped with electric motors have been accepted. In kit form, the fuselages are even designed with this in mind. Electric propulsion has also sparked a “quiet revolution” in manned gliding. In addition to the widely used retractable engines, electric motors built into the nose of the fuselage are also being used in this field. The technical term for this is “FES” = Front Electric Sustainer. This

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All information is provided without guarantee—Accuracy: +/-10%

Propulsion according to e-Calc.

If you look into the many suppliers of large sailboats, you’ll find a huge selection. However, not all models are readily available—so patience is key. I’ve had good experiences with Chocofly. So I’ll start by checking out what’s available from “local” suppliers.

• Slow thermal flying is possible—not a “specialized” racing glider
• Easy to fly (from what I’ve heard)
• FES propulsion (easy installation of a motor in the fuselage nose)
• Two-stage landing gear fits
• High-wing configuration (distance from wing to ground facilitates ground takeoff/landing)
• The battery should fit in front of the landing gear—another reason for using only 6b cells

The design and configuration of the powerplant by Leomotion have proven to be absolutely trouble-free and successful in practical operation. The takeoff distance on a paved runway is 10 to 15 m. Takeoff is also easy on closely mowed grass. Two climb flights with a little reserve to “make it back.” Flights that are worthwhile in thermals. And the others are simply wonderful experiences.