RC Glider High-Launch Competition (F3B) in Thun

Text: R. Schaub; Photos: P. Küng

Just like last year, the Thun Model Aircraft Club hosted the Swiss Championships at the Thuner Allmend. The organizers and the venue make for an exceptionally fortunate combination. The organization went so smoothly that it could hardly be improved upon. The flying field, with its impressive Alpine panorama, allows for high launches in three cardinal directions. This proved to be an advantage, as the weak thermal winds on that wonderful, cloudless day came from various directions. Indeed, it seems as though the people of Thun have a monopoly on good weather.

The measuring device rented by MG Interlaken is capable of meeting even the highest standards and played a key role in ensuring the competition ran smoothly. Since the mirror sighting system used for distance and speed flights is unique in Switzerland, a slightly more detailed description is sure to be of interest. Instead of the usual sighting rods with taut strings, four mirrors firmly bolted to concrete bases are used, forming a rectangle measuring 20×50 m, which allows for simultaneous flights of

two models. With adjustable, absolutely backlash-free tip bearings, the mirrors can be swiveled at right angles to the flight axis, allowing the model to be tracked even when it is farther away from the course. As shown in Figures 2 and 3, a semicircular wire projects a line onto the mirror. The operator must look at the mirror so that the wire and

are identical to its reflection, and as soon as the model flies over this line, it activates an electric switch that triggers an audible signal. Since, for example, a horn is used for one pair of mirrors and a bell for the other, the pilot need only focus on his own signal to turn immediately. This prevents misunderstandings and communication delays.

such as those known from the conventional flag-signal system. Incidentally, the wire described above allows the mirrors to be aligned with such precision that the deviation from a right angle at a height of 150 meters is only a few centimeters. To ensure that the models are clearly visible on the mirrors even in the rain, the mirrors are treated with a water-beading agent.

In speed flying, the push buttons automatically trigger an electronic timer, allowing times to be measured to the nearest hundredth of a second. It goes without saying that the reaction time is many times longer than this and must be taken into account when evaluating the times.

To measure the length of the launch line, the device now mandated by the AeCS Technical Commission was used, which allows for measurements that are beyond any doubt. During each discipline, one competitor was selected at random to verify the line length, which was done immediately after the launch. With the exception of one case, no disqualifications had to be issued due to an excessively long launch cord; lessons had clearly been learned from last year’s incidents. But now, let’s turn to the course of the competition itself.

Four rounds were flown in the order B+A / A+C / A+B and A+C, with no scores discarded. Of the 20 pilots eligible to start (22 were registered, despite verification by the regional chairmen), 19 were present at the briefing.

As is well known, the distance flight was reduced to a maximum of 12 lengths starting this year. In the first round, G. Läderach (MG Thun), R. Baumgartner (MG Wettingen), and E. Haigis (MG St. Gallen) completed this distance. In the endurance flight, with thermals still weak, H. Bertschi (MG Frauenfeld) claimed the “thousander” with 356 seconds and 90 landing points. After this

round, G. Läderach led by one point ahead of H. Stoll (MG Bülach), closely followed by F. Schenk (MG Wettingen).

In the endurance flight of the second round, H. Kuster (MG Oberbaselbiet) came out on top with 360 seconds and 90 landing points. However, even the competitors who had been in the lead up to that point lost only a few points to him. Only the dominant 1978 Region 5 champion, R. Binkert (MG Wehntal), had some bad luck. During the high launch, the Silch snapped, and on the retry, the model veered off course and sustained minor damage, making another launch impossible in the remaining time. With this zero score, R. Binkert could no longer contend for the championship title, even though he was able to add 1,000 points to his total in the subsequent speed flight with a time of 13.2 seconds. In this round, however, last year’s winner, P. Gerber (MG Thun), with his rotary-wing model, scored only 37 points (13.7 seconds) short of the maximum. Unlike most pilots, who flew the turn in a knife-edge flight, he performed it with a half roll and a half loop coming out of an inverted flight. The Wettingen participants, P. Käufeler and F. Schenk, posted the next-best times at 14.0s and 14.2s. At the halfway point, F. Schenk was in the lead ahead of B. Sieber (MG Mörsburg), G. Läderach, and P. Gerber.

The endurance flight of the third round went to B. Sieber with 352 seconds and 95 landing points. In doing so, he demonstrated his exceptional knack for finding thermals, as his colleagues in the same group—who, like him, were among the leaders—managed only about 3 minutes. Since he was also among the four pilots who flew 12 lengths in the distance flight, this round earned him the maximum of 2,000 points. Thus

He took the lead with a margin of nearly 300 points—a lead he held until the very end—ahead of F. Schenk, P. Gerber, and H. Stoll.

In the endurance flight of the final round, the third starting group faced unfavorable conditions. R. Binkert, who was affected by these conditions, put on an impressive performance, flying his heavy model for nearly 3 minutes longer than his competitors in the same group, despite having a remaining altitude of approximately 40 meters. In contrast, the pilots in starting groups 4 and 5 had it much easier in the emerging, widespread evening thermals, and it is by no means surprising that the 1,000-point flight was achieved during this time by R. Baumgartner (MG Wettingen) achieved a time of 360s and 95 landing points. Since he also clocked a solid 13.2s in the subsequent speed flight—just behind R. Binkert (13.0s)—he was able to move up a few places in the rankings.

F. Schenk had a poor endurance flight in the unlucky third starting group and had to swap places in the final standings with P. Gerber, who landed most reliably with 370 out of a possible 400 points. The second-best performer in this category was P. Dellenbach (MG Nidwalden) with 330 points.

The new Swiss champion, Bruno Sieber of MG Mörsburg (Winterthur), won primarily due to his consistent performance, averaging over 900 points per discipline.

The high-launch technique was further improved compared to last year. Most participants launched directly or with the help of a second person who held the end of the line and either stopped or ran alongside depending on the model’s climb rate. Relatively few false starts were observed.

Surprisingly, the multi-

Many of the participants’ models lacked ailerons and, in some cases, even speed brakes. The wing loading was generally less than 30 g/dm², and the wingspans ranged from 2.8 to 3.2 meters. However, B. Sieber and R. Binkert demonstrated that very good performance can be achieved even with wing loading around 40 g/dm² and that these models can be launched directly, even in practically windless conditions.

The competition was decided primarily on endurance flight, as thermal hunting apparently presented challenges for many pilots. Only when a few top pilots in Switzerland manage to achieve times around 10 seconds in speed flight—as demonstrated by the Austrian Working Group for Model Aircraft Development—will this discipline gain in importance.

Finally, we would like to extend our heartfelt thanks to MG Thun, its chairman H.P. Stähli, and the more than 50 full-time volunteers for their excellent organizational work. The frequency monitoring team, led by the tireless W. Prantl, also proved its necessity when a “Sunday pilot” was indulging in his hobby at the other end of the airfield and was detected only thanks to the frequency monitoring.

We hope that we will be able to enjoy the hospitality of the people of Thun again next year.

With the NM qualifier held on September 24, three of the competitions required for the nomination of the new F3B national team have now taken place. For selection purposes, only the two best results count; the worst competition is discarded. In the event of a tie, the better discarded result is decisive.

The new F3B national team is composed as follows:

Pilots

• Peter Gerber, MG Thun
• Ruedi Baumgartner, MG Wettingen
• Fredy Schenk, MG Wettingen

Reserve Pilot

Peter Aeberli, MG Erlenbach

* Withdrew from the team