A replica with many unusual challenges—the Air Glacier “Grapevine and Apricot Sprayer”

The kit, along with the mechanical components, rotor head, and tail rotor, are from Vario Helicopter in Germany. Unfortunately, Vario’s kits do not always match the real-world model, so adjustments and modifications are essential when building a scale model. Markus knew this
as well, and he made a few adjustments, which are discussed in detail here in this report.

For example, he cut the most distinctive feature of the kit—the struts of the canopy glazing—narrower from the start. Since the glazing panels are supplied
larger than the openings, they could be easily adapted to fit the larger openings. However, the glazing was not glued in place; instead, it was clamped and screwed into position using matching polystyrene counter-ribs. The screw head on the outside of the cockpit also serves as an imitation of the rivets.

The Vario kit includes blue bottles for the kerosene fuel system. The included tank covers do not completely cover these tanks, which looks very unsightly on the finished scale model. Markus Lehmann solved this issue by building the kerosene tanks himself out of fiberglass-reinforced plastic (FRP) and laminating them into these covers. This allowed the tank capacity to be increased slightly to two liters, and the tanks became invisible.

In many cases, a great deal can be achieved in the end result with relatively little effort, but it’s not always clear why manufacturers haven’t made any changes to such fundamental design elements over the years to make things easier for or support model builders. Many 3D-printed parts from Scale Print, which were assembled, round out the model’s overall appearance.

From the very beginning, the spray system was the builder’s top priority. He slightly underestimated that it would become the model’s biggest challenge and take so much time. During two visits to Sion, in the hallowed halls of Air Glacier, Markus was able to take countless photos of the original spray system and measure it in detail. Using this documentation, everything was transferred to paper (CAD) and scaled to the correct proportions.

We soon found the right partner in Stefan Radau’s company, Scale Print, which was able to produce the many individual parts needed for the project. Connections, mounts, bends, dummy nozzles, fittings, and much more—for these kinds of tasks, the 3D printer is the ideal solution in today’s world and can save a lot of work.

The arms to which the nozzles are attached were made from PVC pipes. Water is also channeled through the inside of the pipes to the nozzles. The two side tanks for
the spray solution (water) were not available commercially and therefore could not be purchased. A prototype was created, and the tanks were molded accordingly. The builder designed and fabricated the complex mounting system for them himself. It took several attempts to eliminate the vibrations in the tanks during flight.

Since Markus Lehmann was breaking completely new ground with this spraying system and could not find anyone who had ever implemented anything like it before, the entire system was installed on a trainer model to
conduct the initial tests. After the first flight, the disappointment was immense: the water did not produce the desired mist, but instead shot out of the nozzles in a jet. The pump pressure was reduced, different pumps were installed, and nozzles from another manufacturer were purchased, but it just wouldn’t work.

While doing further research online, the builder came across a video from a drone
manufacturer that offers drones equipped with spray systems in Japan for managing rice paddies. After a few emails back and forth, the electronics for controlling the pumps and a pump arrived in Prättigau, where they were installed and tested that very same day. The result was immediately worlds better, but still not quite satisfactory for the perfectionist Markus.

Sometimes, however, as the saying goes, the final solution is right under your nose. From the very beginning, nozzles

Gardena brand products in various models purchased from the hardware store. In his landscaping business, however, he uses products from the long-established Swiss company Birchmeier. He modified one such nozzle from a backpack sprayer on a lathe to fit his needs and assembled it as a prototype. During the subsequent flight, the results were overwhelming and met expectations exactly, so additional units were immediately ordered from the manufacturer. The system has 18 spray nozzles on each side, though only four of them work with water. This setup produced the best results.

After these extensive and time-consuming tests, which lasted over half a year, the system was finally completed and mounted on the scale model itself.

With the Air Glacier “spray helicopter,” Markus has created a model that is a rare sight indeed. In about 1½
years of construction, he has created something truly one-of-a-kind. With its impressive flight profile and from a sufficient distance, it is almost indistinguishable from the real thing in the air—if only there were some grapevines or apricot trees in the background.

Photos: Markus Lehmann,
Andreas Maier, MG Schöftland,
Hansueli Tschiemer