Losing altitude at White Sheet Hill — but not for long!

Downsizing the Bergfalke IV

Part II: So how did it all pan out?

Readers who have not already done so may want to read Part I: What do you mean you don’t remember the cabriolet version with winglets? before proceeding with this article. — Ed.

All-up weight without the 4S LiPo turned out to be 10lbs (4.5kg) which at first I thought a little high until I remembered that this was a two-seat glider, therefore larger than its single-seat brethren. I can’t absolutely guarantee it, but should anyone prefer to do a standard version of this machine, then my original ¼-scale Bergfalke canopy should be a reasonable fit. The overall size is one of comfort when it comes to self-launching, although I prefer to let one of the posse take over when the motor is running. Rigging is pretty quick and simple, although you do have to remember to fit the winglets! The Turnigy G32 motor gives plenty of urge via the 4S LiPo, despite the manufacturer’s specs showing a max weight of 6lbs, but then, that’s the efficiency of gliders for you. I don’t think you can buy these motors any more, but the included specs in Part I (link above) last month should point the way to an alternative.

Left: View of the cockpit internals | Centre: Old-fashioned rubber band wing retention. | Right: The Smallpiece Super-Separator release evident on the underside of the fuselage. Click any image for more detail.

In flight the model is smooth and predictable, and at low speed is nice and safe, with plenty of warning of the approach of the stall. The brakes, in conjunction with up-lifting ailerons are very effective, allowing for precision slopeside landings when space is tight.

Left: Aerotow take off at Central Model Flying Club (CMFC). | Right: Motley Crew gives a manual launch at White Sheet Hill.

It has to be admitted that when light winds are in the forecast for expeditions to the slope, this Bergfalke is the one I reach for rather than the larger version for reasons of practicability, to the extent that to date is has flown mostly with the moustache.

Left: In Purist Mode at the White Sheet Hill. | Centre: Light winds at a White Sheet Hill Scale Fly-In event. | Right: Flying low at the Wessex Soaring Association’s Stoney Down slope.

Should anyone fancy a go, the working drawings along with over 150 construction photos are available free-of-charge right here from the New RC Soaring Digest. See Resources below for the link.

Left: Mobius 4K cam view of aerotow launch at CMFC. | Right: Another Mobius 4K cam view of sunset flying session also at CMFC.

If you want to see the bird in action check out my Baby Bergfalke IV video on YouTube which is also linked below.

Author gives scale to 1:4.7 Bergfalke 4.

Thanks for reading and by all means, please let me know if you have any questions by leaving a comment in the Responses sections. You get there by clicking the 💬 below.

©2023 Chris Williams

Resources

• Bergfalke IV Plans and Construction Photos — Working drawings of the Bergfalke IV in PDF format along with over 150 construction photos.
• The Williams Anthology — The collected works of Chris Williams as found in the pages of the New RC Soaring Digest.
• Baby Bergfalke IV by the author on YouTube. — “Reduced scale version of the Bergfalke IV, given the fresh-air treatment and fitted with a moustache.”
• Central Model Flying Club — “welcomes all pilots of fixed wing, glider, and electric models to our Flying Club. Club field is situated in rural Shropshire, near to the Severn Valley Country Park and most types of models can be accommodated…”
• Wessex Soaring Association — “For 40 years the Wessex Soaring Association has been dedicated to the pursuit of all forms of radio controlled model gliding. With an impressive range of slope soaring sites to cover virtually all wind directions…”
• White Sheet Hill AKA Whitesheet Hill according to Wikipedia. — “a hill in the English county of Wiltshire. As one of the most westerly areas of downland in Britain the area is noted for its chalky farmland which contains a rich variety of rare and protected fauna and flora…”

The posse’s total fleet of e-assist Bergfalke 4’s. The 4.7:1-scale version is in the foreground while the quarter scale versions are in the background.

All images, tables and videos by the author. Read the next article in this issue, return to the previous article in this issue or go to the table of contents. A PDF version of this article, or the entire issue, is available upon request.