Kupper Ku4 Elefant scale 1:6

[bocorvin]

Building Kupper Ku 4 (Elefant) scale 1:6, built from the FMT plans

Fotor had previously owned an Elefant, see this link

www.retroplane.net/forum/viewtopic.php?p=68869

but is broke its wing when towed and he decided to build another one, it is surely a remarkable glider!

Fotor writes;
This thread (building thread on the Dutch MBF) started at the end of 2013. 11.5 years ago. The last construction activities were 2.5 years ago, and the construction breaks have become longer and longer.

After those last construction activities, I had to slow down in many areas. My desire to build has also diminished. Well... Will that Elefant ever be completed? It would be a shame if it weren't, because it's such a unique machine.
I started thinking about whether I wanted to finish this project. I still want to, but at the same time, I seem to have lacked the right motivation for a long time. That's why I decided to look for someone who would be willing to take over the project.

The first name that came to mind was Vincent de Bode, a good friend, fellow club member and fellow townsman, and a gifted model builder. He had to sleep a night over it to decide, but he's going to take over the project. I'm happy about that! Vincent has already built many “special” scale models and is a fan of unique gliders. What's more, he's a very talented builder.
Vincent's idea was to have a kind of co-ownership after the build so that I can still fly the Elefant from time to time. I think that's great! I will probably also be the one to fly it in.

Vincent came by today and I handed over all the materials. With a little pain in my heart, but with more joy that the chance of the Elefant flying has become a lot bigger.









Vincent (DB) writes further

First a few remarks about the Ku 4 an extreme glider from the 30’s, with a wingspan of 30! Meters.
Thomas posted an article about it on 12/01/2025 17:59 on this forum





Now my adventures finishing this glider;
Just under a week ago, I found myself with a three-quarters completed Elefant (Ku4) in my attic. It took a moment to process, something like, what, where, how? But apparently I like that. I found the necessary information on Retroplane, Thomas had posted a beautiful set of photos on Retroplane, I'll include a few.
This (extreme) aircraft hasn't flown much, with a wingspan of 30 metres and weighing just under 500 kg, it's not exactly a handy structure, but that's less of an issue for the model. The Ku 4 or Elefant (it was heavy, big, grey and had two fins) broke up while flying in the clouds (with minimal instruments and virtually no flaps), but the pilot landed safely with a parachute. The plane was completely destroyed, in short, it surely was a daring project.

Then I sat down quietly in front of Raymond's construction, which was very neatly built and surely complicated! The tip ribs are really tiny, compliments to Raymond.

Where to start?
After studying the photos and the FMT drawing (which Raymond included), I first filed the nose cone into shape.





Then the front of the neck; the photos were different from the FMT drawing, so I made it a bit straighter. Inside the fuselage, I made some shelves with space for ballast, the receiver battery and the uncoupler servo.





I also made the core of the skate simple, using 8 mm balsa wood without suspension.





I put in the pilot, he realy had to sit that low.

To be continued

Vincent (DB)

[bocorvin]

I continued with the nose of the fuselage, glued 0.6 mm plywood on both sides of the skate and the lower planks of the fuselage.
Once the fuselage has been glassed (with 25 gram cloth) the skate itself will be attached.





The horizonral stabiloizer mounting plate with wooden spacers so that the tail will not crackwhen tightening the bolts.





Gradually, I got more familiar with the construction. I noticed that in the design (drawing of the FMT), the fairly thin tail boom was made of balsa wood. A strong nose, large wing and a stabiliser with two fins all connected with a balsa tube, combined with my landings, I was afraid that it would break quite easily. I therefore decided to make four “girders” from glass roving.

Using a specially made sanding block, I sanded four 5 x 1 mm grooves, which was good exercise for my muscles...





Pre-impregnated glass roving (four per groove) were anchored to sturdy points in the fuselage nose









This gave me a bit more peace of mind.

Then the cockpit. The pilot (Kronfeld I presume) could enter through a hatch, when closed only the upper half of his head protruded above the fuselage. The instrument panel is very close!

More nice photos from Thomas article of the Ku4









After the necessary gluing and sanding, this is what it looks like.









I'm leaving the top of the fuselage open for now, so I can still reach it, first to finish the wings with servos.


Vincent(DB).