Peter Coombe Posted November 8, 2009 Share Posted November 8, 2009 I have nearly completed a Balsa USA 1/4 scale J3 Cub.A very nice kit but have hit a snag.Wing retention is reliant on four cap head screws assembled from within the cabin,through root ribs and into captive nuts.The struts have to be loose fitted simultaneously and all this can only be accomplished with model inverted on a frame.Access to the screw heads is very restricted.I have made up various Allen key drivers,ball ends etc,even a universal joint device,with moderate success,but dread attempting it in the cold and wind at the field.Takes 25 minutes in the workshop!I am considering some sort of over-centre toggle arrangement to apply tension between each opposing securing screws.The toggles would need to be no more than 3/4" wide for it to fit within the existing structure.I would appreciate a sketch from anyone with engineering skills.Can cope with silver soldering and basic metal work but dont know how to design them. Quote Link to comment Share on other sites More sharing options...
Ed Kershaw Posted November 8, 2009 Share Posted November 8, 2009 Peter, a photo showing the problem would be helpful. If I understand you correctly, you are proposing to pull the wing roots together with a toggle clamp rather than screw them to the sides of the upper cabin walls. This would put the cabin under compression. Is that OK? If it is, why not use a turnbuckle? Then your only difficulty is making a LH thread, which only involves a small investment of tools from Model Fixings. Or have I misunderstood things? Ed Quote Link to comment Share on other sites More sharing options...
Stephen Grigg Posted November 9, 2009 Share Posted November 9, 2009 By a big Transit Peter Quote Link to comment Share on other sites More sharing options...
Martin_H Posted November 9, 2009 Share Posted November 9, 2009 MAYBE you could put some dowels (carbon or ali tube) through the fuselage and into hardwood blocks in the wing root, which can all be drilled and tapped to take a VERTICAL bolt through the top of the wing. My main concern would be what might happen with an overcentre device when one invariably has an untidy arrival and the wing bolts usually fail, giving a measure of survivability to the remainder of the structure. Quote Link to comment Share on other sites More sharing options...
Martin_H Posted November 9, 2009 Share Posted November 9, 2009 Sort of this idea - you could fit the bolts from underneath though this sort of thing would mean reworking the wing roots Quote Link to comment Share on other sites More sharing options...
Peter Coombe Posted November 9, 2009 Author Share Posted November 9, 2009 Thanks Martin,Stephen and Ed for your wise suggestions (mostly)Have very limited computer skills but will delve into this site to try to discover how to add a photo or two in due course to iluminate the difficulty. Quote Link to comment Share on other sites More sharing options...
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