180 Pages of Free Flight

Modern free-flight models are high-tech machines whose mastery requires expertise in a wide range of engineering disciplines. In the case of the F1A category (high-launch gliders), athletic ability is also a factor. With a pull of over 40 kg, these 410-gram gliders are launched using a 50-meter line to speeds exceeding 200 km/h and heights of over 110 meters. Carbon and Kevlar structures can withstand forces exceeding 100 times the model’s weight. One of the inventors of this technology is the

Swiss engineer and model builder Dieter Siebenmann. To mark his 80th birthday, the free-flight journal “Thermiksense” is publishing 47 technical articles by Dieter Siebenmann on aerodynamics, design, and model aircraft categories from the past 35 years. Dieter’s goal is to apply his ETH-trained engineering knowledge in a practical way and explain it in a way that’s relevant to real-world applications. As a result, it’s not uncommon to read in technical discussions in “Thermiksense,” especially when things get complicated: “We’ll have to ask Dieter about that.”

The book answers many questions that those interested in aviation and engineering will find highly beneficial to read. Between the lines, one can sense

Dieter Siebenmann’s sense of humor and broad education. The articles address many technical questions in the fields of lightweight construction and flight stability. They shed light on the evolution of model aviation, which was made possible largely by the designs and introduction of lightweight materials such as aluminum, carbon fiber, fiberglass, Kevlar, and boron fibers.

When it comes to acceleration, high loads, and lightweight construction, one’s thoughts quickly turn to rockets and lightweight vehicles. Dieter Siebenmann worked on the Ariane 4 rocket and continued his career on the “Solar Impulse” project.

Fortunately, Dieter is in good health and

can be found at F1B competitions (rubber-powered gliders). He was European champion in indoor gliding in the F1D class (the premier class in indoor gliding—55 cm wingspan, 1.4 g weight) and even defended his 2022 Swiss indoor gliding F1D championship title in November 2023. Instead of “asking Dieter,” you can purchase the 180-page A4-format book from “Thermiksense” (www.thermiksense.de) or directly at https://www.thermiksense.de/abo_probeheft/)) for €10 plus €10 shipping. Due to high demand, this is already the second edition.