When everything is square, it is time to add baldachin straps 570, the connection between fuselage and the upper wing section. Glue the fillers 567 and 568 to fuse formers 502 and 503, and secure them with 4 sheet metal screws 569 (use the pre-drilled holes)
when the glue has set, enlarge the holes to 6mm to fit 570 and brass tube 571. Now the baldachin straps with brass tubes can be inserted into the holes.
Next clamp the straps 572 in place, the front parts have a distance of 12-13mm to the balsa root ribs, the rear ones ca 3mm. The different dimensions are caused by the fact that the straps, when seen from the front must be in line. Because of the symmetrical profile and negative incidence, the rear supports are longer.
The picture shows the mounting of the straps onto the wing, the fixings on the baldachin are done simmilarly.
Brass tubes 573 and 574 as well as 575 are fitted to the straps. Use an M3 bolt to keep the parts in place. When everything fits, the centre-section is still lying snug in the support . Now the holes in 572 can be drilled into the wood. I use a Dremel-drill with a 2.5 mm bit. (keep it as long as possible) Make sure the holes only go through the support spars, not the main spars. If you drill too deep, you will weaken the main spars!
We drill the front support from the front, and the rear ones can be drilled by using a flexible extension on the drill. Once the 2.5mm holes are ready, they must be enlarged to 3 mm. Easiest is to disassemble everything and drill them by hand. Of course you could drill the holes directly with 3mm but if the straps move intentionally or not, it is a lot more work to get things straightened again.
When the holes are enlarged to 3mm, the strap can be mounted with M3 bolts 576 en initially secured with normal nuts. After the straps are fitted, remove tubes 573, 574 and 575. Next, the parts must be either soldered or glued together. Both ways work. When you choose to glue the parts, you furst have to sand the parts clean, and degrease them properly. The advantage is that the parts can be glued in place. You only have to make sure not to glue the M3 bolts and tubes. Disadvantage: you never know how strong the glue joint is. Brazing has the advantage that it is easier to see if you have a good joint.
Below is the description of the brazing.
To secure the position of the brass parts and sleeves, I use narrow brass strips just below 573 and 574 to secure the parts against movements. (If you look in the picture, it’s the bits that look like twisted wire (bottom of page 10))
After the location is set, you can remove the lot. Before I braze the parts, I drill a small 1 mm hole just before the flat section of parts 573 and 574. This to allow the solder to flow into the void, and for gasses to escape. When you are finished, it is easiest to file away the brass strips, or at least remove them so far that they will not be visible later on. Make sure you clean the joint, so no flux is left.