Electricity from the Ground at the Hinwil Model Aircraft Club

The number of members with electric model airplanes is steadily increasing. As a model flying club, we view this trend positively and would like to encourage it. The long distance to the clubhouse has prevented many members—especially those with larger models—from converting their larger models to electric power. For these reasons, the Hinwil Model Flying Club sought a way to conveniently charge these models at the launch site.

To solve our problem, we contacted our model aviation colleague Jürg Eichenberger, owner of Spälti Elektro AG in Hinwil. A shaft was already in place on site, in which a coupling socket with a 32-amp fuse—intended for larger events—had been installed. Jürg Eichenberger introduced us to his product, Terramo, and explained how we could best configure it.

We enclosed the power cable in a waterproof rubber housing, which could be integrated into the existing shaft. The existing 32-amp connector was then connected to the Terramo inside the rubber housing along with the power supply cable, ensuring that we still have all options for power supply available to us.

The Terramo itself has three Type 25 outlets and a circuit breaker providing 16-amp protection. A quarter-turn with a 10-mm Allen wrench is all it takes to unlock the Terramo, after which it rises approximately 15 centimeters out of the ground. Without any additional expense, our members can now take advantage of three 230-volt outlets rated at a maximum of 16 amps and charge batteries of any size directly at the launch site. After flying, the Terramo is simply pressed back into the ground with the foot.

Since we’re located right next to a dirt road used by farm equipment, we needed a system that wouldn’t stick out and could also withstand vehicle traffic. We also didn’t want to mar the landscape with an unsightly power pole. With the Terramo, we’ve now found the perfect solution—one that’s not only invisible but can also withstand loads of up to three metric tons. Another advantage of the recessed installation is that the Terramo is not exposed to the elements. The entire electrical system, including the outlets, remains well protected inside the Terramo’s housing.

Our system is equipped with a plastic tray that houses the electrical supply cable. We have also fitted this tray with a groundwater check valve. Should water still penetrate the system, the tray drains automatically. In addition, the system itself is designed to be watertight. This ensures that water cannot reach the electrical components. For added safety, the Terramo has its own ground-fault circuit interrupter (GFCI). To prevent condensation, a small heater is located inside the housing. This ensures that operation at low temperatures in winter is not a problem.

We first put the system into operation at the F5J Swiss Championships, where it was used primarily by junior pilots, who typically have only a few batteries due to cost considerations. We also made extensive use of the ability to charge batteries right at the launch site during our junior development course. As we’ve observed, the system is also being used by our senior members. We’ve received consistently positive feedback from all users.

The MG Hinwil would like to thank Jürg Eichenberger and Spälti AG for their generous support of this project.