I have built somewhere in the neighborhood of 30 Ringmasters within the last few years and have never done this. I use the kit put out by RSM and it utilizes ad piece of 1/8" strip of plywood that is glued to the inside of the leading edge that runs the length of the 3 center ribs. The center rib is notched at the front so the plywood piece will slip through it. I have never had wing fold doing this. My personal opinion from what you are showing that Brodak recommends, is overkill.
Mike
This "T" piece is not intended to keep the wing together. The intent is to firmly connect the wing to the fuselage at the leading edge, which has been a disastrous weak point on the Ringmaster since it was first kitted in about 1949. The original arrangement could almost be assured to start cracking sometime after you started attempting to start the engine the first time - but before it actually started. The design is terrible and the doubler only contacted the wing for about an inch (just the LE wood), and at least in the original, the material used, specifically luan or mahogany plywood "door skin", was so incredibly weak that there is basically nothing you can do and no glue that would hold this together. Either the glue joint broke, the attachment to the balsa broke, or the doubler itself broke.
The "T" joiner is intended to put much a structural connection between the wing and fuselage. I don't know what the Brodak instructions say, but the original idea was to build the wing complete, with the "t" sticking out the front of the wing as shown. Then, you glue the wing into the balsa fuselage, where you have cut a corresponding slot. This spreads the load on both the wing and fuse connection. Then, put the plywood doublers over the top of the "T". The doublers are solid and do not have a slot for the "T" to go through, they cover it up.
The Brodak version appears to cut the slots in the doubler so you can slip it together after you glue the doublers on. That makes it easier to assemble the fuselage since you can put the doublers on flat, and probably OK as long as you use epoxy and fit it up, but it does depend entirely on the glue to hold it, rather than capturing it like the original design. Note also that the doubler goes much further back on the fuselage, reducing the load on the fuse/wing joint compared to the original.
If you are using a modern engine like a 15FP, 20/25FP or something relatively smooth like a Veco 19bb, etc, at high revs, it may not be absolutely necessary, particularly considering the modern kits use decent material for the doubler (much, much more durable than the door skin material). It doesn't hurt anything and it's not to difficult to deal with. It would be nicer if they made the kit use it by default and cut the slots at the factory, but it's easy enough to do by hand.
If you are using a vintage engine like a Fox/McCoy 35, it is my considered opinion that it is nearly a *must* to use the "T" joiner, no matter how good it fits, how good the plywood is, and how strong 30-minute epoxy might be, it's still going to shake itself apart in relatively short order. It did it in 1949 and it will still do it today.
In any case, it doesn't hurt anything and fixes a notorious weak point.
Brett
Topic: Brodak Ringmaster (Read 2773 times)
