Notes from Ron Fox of
Australia
(all images can be enlarged)

		Fig-1 - Here is a photo of the jig we used to set up the frames to ensure they were in alignment

Fig-2

Fig-3

Fig-4

Fig-5

And finally Ron shows us his project assmbled and almost ready for covering. Thanks Ron for sharing your observations

Looking at the photos I remember how we tested each support for its correct height by using the straight edge of the timber jig and comparing the height of the support to the plan Fig-2. That gets the height of each stand correct but you still have to pack or sand the support to fit the former. The formers are correct, the supports were incorrectly dawn. See Fig-3 where we altered supports for F3 through F9 to get a smooth curve and ensured the horizontal stringers either side of the keel maintained a smooth shape. If you use a jig like ours with a block at the bottom of the support, you can slide the support up & down before finally fixing it to the block. Fix the block to the jig and everything stays in shape!

We also used bamboo sticks as bracing for the pipe effect, light & effective but a lot of effort.

We also used a different tailplane connection where the elevators slide back from in front of the tail engaging slots in the inner end of the elevators with the wire actuator. The wire is soldered to an arm that is always connected to the push rod – less slop that way. Fig-4. Slip brass tube over each straight arms of the wire to the width of the rudder post and then bend the arms back 90 degrees to the arm, following the rudder profile. Both arms need to be parallel or one elevator will have more up in it. The slots in the elevators were formed by gluing thin ply as a sandwich spaced by balsa, the gap between the ply is the size of the wire used. It helps strengthen the elevator. Fig-5


The Rudder & Elevator frames were made from laminating 8 wet strips of balsa around blocks of chipboard. Cover the chipboard with plastic wrap to stop the water/glue soaking in. We were making about 10 models at the same time as a club project so we mass produced some of the parts!

"We chose to use balsa sheeted foam cores instead of the ribbed wing. However we did have some problems mating the fuz formers to the subframe but this was discovered in the dry run set up. As Chris states in his building tips, never trust any plan (even his!), it is too easy for mistakes to creep in - measure everything and use your common sense. Ask someone if it doesn't seem right to you - it probably isn't!
My Bergfalke is now ready to fly after many months languishing in the workshop while work got in the way. I thoughly enjoyed building the Bergfalke, it should have only taken maybe 3 months to complete, not the best part of the year as in my case. I will be building a set of ribbed wings next for the Bergfalke just to see the difference between the balsa sheeted foam and the built up wings in the air.
Check out www.scalesoaringaustralia.com/Bergfalke.htm for some of the Bergfalkes built by VARMS members.
Have fun with your building, I find it as rewarding as flying the finished product. "

"Ron, when you write : " mating the fuz formers to the subframe" do you mean the jig supports for the formers ?
i.e. F1a, F2a, etc. ?
I had my plans scanned and had the formers and supports lasercut, and while the parts do match the plans, the formers and jig supports do not match each other.
If this is the same issue you had, how did you resolve it ?
Here some pics : http://www.mkrusa.com/Bergfalke.htm"

"Yes, we had problems with the jig supports. Cut yourself stringers of balsa or soft wood. Assemble the formers by hand (many hands help!) and fit the main horizontal soft stringer in place. The stringer will show you which formers are high or low. Pack the top of the support with strip balsa to raise or sand/cut the support to lower the former until the sringers looks right. The curves should flow when looking along the stringer without flexing up or down. Test fit all of the stringers. We used a centre string for alignment and side rails. I will send you a photo of the framing stage directly as I don't have a web page to link to. "