Originally Posted by
acdii
If you want a rigid wing, Spruce spars make it so. The LT-40 has Spruce and I think so did my 4*120. One thing I recommend if you are going with a bar as the joiner over a tube, make sure your wing box is well glued, and make double sure the webbing goes to the edge of each spar, it should go to the top and bottom of the wing. In fact I would use 1/16th or better ply for the webbing and maybe even pin it to the spars. I lost my 4*120 ARF due to the webbing not being 100% attached to the spars. They only came to the inside of the spars and after a few flights separated from the spar and eventually cracked the ribs enough that the wing failed.
One other thing, the front pin used to secure the wing to the fuse, I would not use a center pin where the inside rib is part of it, I would use a dowel secured between two ribs with hard balsa. Again, the 4* was like this and eventually it too had cracked after a couple flights. My T-Clips is setup with the dowels between ribs and it is one tight flying wing.
Hello acdii,
Nice to read you acdii.
I already posted how I am planning to build the wing joining laminated bars.
One quarter ( 1/4" ) inch thick plus the thickness of the epoxy and their height ( width ) will be 1 1/4" for the main spar and 7/8" for the rear spar. The boxes will be made of 1/4" x the thickness of the bars at their tops and bottoms and the vertical sides will be made of 1/8" - 3 ply birch plywood going full thickness of the airfoil which is 1 3/4" at the main spar and 1 1/4" at the rear spar.
I visualize that as being quite strong. Epoxy ( 30 min ) will be used for the binding.
For anyone who has the drawings, the W1 ribs will be cut to have the boxes in one continuous length and the D1 doublers will be replaced by the front vertical part of the boxes. A similar build will be at the front of the rear spar.
I think that the boxes can terminate butting against the W2 ribs closest to the fuselage. That would give the joining bars a length of 12 inches. If we also consider the installation of wing struts, we have pretty strong wings plus the covering being woven fabric ( Ceconite ) glued to all contact surfaces with nitrate dope.
The webbing does go to the top amd bottom of the ribs ( to the fabric covering ).
I have not yet worked out the details of the wings fastening to the fuselage but it is likely to be similar to what I did on my Spectra with equivalent of dowels at the rear and screws at the front. Some fuselage reinforcement is needed there. More figurations will find the solutions.
Any suggestion(s) to improve on the above would be highly appreciated.
Zor