Bob Cotsford Posted August 13, 2014 Share Posted August 13, 2014 I don't know if this is the right section for this, but here goes anyway - I'm sure the mods will relocate it if need be. How do you work out what size wing joiner to use? In the past I've gone by 'X model uses this size so I'll use the same' but I'm in unknown territory here. Suppose we take as an example an 84" monoplane, 30cc power, conventional aerobatic style (not 3D) with a thick section wing so lets say it's around the 6-7kg mark. If you wanted to split the wing so it's easier to store and transport, what size ali tube? 25mm? Looks weedy against a wing that's getting on for around 3" deep at the root. Go up to 35mm or more and it's £30 a section! Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted August 13, 2014 Share Posted August 13, 2014 Personally, I'd want the joiner as deep as possible - so a 3" wing I'd use a 2.5" joiner and make sure the "female" parts of the joiner are in boxes and bonded to the skins top and bottom (if foam) or spars (if built up). No point on skimping (as long as it's light!) on an 84" airframe. fighteraces sell nice aluminium / phenolic joiners if that's any good to you. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 13, 2014 Author Share Posted August 13, 2014 hi Andy, yes, £30 from FA for 50mm, £27 for 37mm. On the King Altair (78", 4kg) I used 25mm and as you say, tied them to the spars using ply doublers on the ribs and blocked them to the spars inbetween. I guess there comes a point where you are trading off strength in the tube against having enough meat left in the ribs to hold it - 2 1/2" in a 3" wing sounds to be getting there with just 1/4" of rib left above and below. I suppose there's always the alternate approach of making the dihedral brace loose with a reinforced box section in the wing to receive it. Much easier to build it into the spar structure and cheap! I feel the need to study the plans a bit more. Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted August 13, 2014 Share Posted August 13, 2014 Bob, This is true! A vertical ply dihedral brace you'd think would easily take care of things, and there will be a trade off between depth and remaining strength in the wing. Glue them solid and have a one piece wing - sorted! Edited By Andy Meade on 13/08/2014 15:00:14 Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 13, 2014 Author Share Posted August 13, 2014 and a hole in the car's tailgate for them to poke through? Sorted Quote Link to comment Share on other sites More sharing options...
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