Sport

A Lance for the Spears

von Andreas Locher
4

When launched, they are thrown like spears—the fast models in the F5B electric glider class.


This model class, which has been constantly evolving since the early 1980s and has essentially reinvented itself time and again, remains one of the most interesting competition classes even today. The two tasks to be completed in F5B share a surprising similarity with a completely different category, namely that of the DLG F3K models... This may sound astonishing, but the models in both classes—F5B and F3K—must perform two completely opposite tasks.

During the spectacular discus launch, the ultralight F3K gliders must withstand high stresses and soar to the greatest possible altitudes with thin airfoils, only to then—in a mysterious transformation!—turn into efficient thermal gliders.

It’s fascinating to see how model development over the past 20 years has managed to combine these conflicting requirements ever more perfectly in these remarkable models.

It’s much the same in F5B: In the first part of the competition task (as many 150-meter runs as possible within a time limit of 200 seconds), the gliders must be powerful, high-speed models, only to then complete a 10-minute gliding task with a precision landing in the second part. Here, too, there are two conflicting requirements for a single model.

Anyone who has followed the development of F5B from its beginnings to the present day has repeatedly marveled at the spirit of innovation, the technical and flying achievements, and the dedication and perseverance of the competitors. Numerous rule changes—some for safety reasons (multiple climbs during cross-country flights), others for fairness (energy limiters)—have made F5B the sophisticated, fair, and extremely demanding competition class it is today. Perhaps these achievements—both technical and in terms of flying skill—have become too much of a given for many model pilots; after all, electric models can now be purchased “plug-and-play.” However, we should not forget that tinkerers and those with perseverance have consistently pushed model aviation forward; this applies, among many others, to free-flight pilots, indoor flight specialists, DLG trialists, and, not least, the tireless F5B enthusiasts.

Unfortunately, participation numbers in this category are shrinking (worldwide); the significant effort required deters many model pilots. This is also reflected in the number of participants at the F5B Swiss Championship on October 12 in Cham, hosted by the Zugerland Model Flying Club, where just 6 pilots took to the air. Without wanting to sound maudlin—it’s like in music: When a type of instrument is played by fewer and fewer people and eventually not at all, then not only does the instrument disappear, but ultimately so does the knowledge and skill associated with it—a kind of extinction, so to speak.

Let me take a stand for the “spears” here: Why not visit an F5B competition again sometime? The displays are breathtaking, and once you’ve figured out the tasks, the competitions are incredibly exciting. And experienced pilots are very willing to help newcomers. Maybe it’ll inspire a few young people again...



Technical Specifications for the F5B Model
Wingspan193.5 cm
Length134 cm
Weight1,550 g to 1,680 g (depending on motor setup)

Standard-Set-up
PropellerGM 18×23
MotorLeomotion L4031/2050 with 7:1 gearbox
ControllerAPD HV 200A
Data LoggerSM Unilog with 400A shunt
Battery10S Gensace Tattu 1400 mAh V4

Performance Data
Maximum engine power7,500 W at 8,500 rpm
Forward acceleration8 g; that is, after a manual launch, the model reaches an altitude of 60 m in 1.5 s and travels at 250 km/h.

Speeds
Maximum speed350 km/h (not reached in competition because the vehicle is not accelerated to its full potential)
Minimum speed50 km/h at a descent rate of 1 m/s



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