Darran Posted August 9, 2013 Share Posted August 9, 2013 I am putting together my tutor 40 trainer and I made what I guess is a rookie mistake when gluing the two wings together, I used 5 minute epoxy and not 30 minute, I also must have mixed it wrong as it started to set rather quickly. the upshot is I have a few millimeter gap where the wings join. Everything looks level but for this gap. Should I fill it with epoxy or gap filler, will it be ok to use the wings or do I need another set. Quote Link to comment Share on other sites More sharing options...
Devcon1 Posted August 9, 2013 Share Posted August 9, 2013 I don't know the model so is there a spar system or are the two wing panels butted together then reinforced somehow.. Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted August 9, 2013 Share Posted August 9, 2013 i would fill the gap and run a wing bandage round the join. but thats me and i am normaly wrong most of the time. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted August 9, 2013 Share Posted August 9, 2013 Mmm, it all depends. Just how many millimeters is a few? Is there any wood-to-wood contact? Are they definitely straight? If the gap really is very small and they are straight you'll get away with it. If they are definitely straight - but the there is some doubt about the quality of the joint it could be fixed with a fibreglass wing bandage. We can tell you more about them if this is the case. If their not straight, or the gap is unacceptable - you've had it I'm afraid. A couple of pictures might help to give a better more specific advise - include something for scale like a rule. BEB Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 10, 2013 Share Posted August 10, 2013 Is this the new Mark 2 Tutor with tapered wings and a large aluminium tube joining the wings together? If it is, you'll get away with it. I'd fill the gap with more epoxy and cover it with wing bandage as Tony suggests. Quote Link to comment Share on other sites More sharing options...
Rick Tee Posted August 10, 2013 Share Posted August 10, 2013 If the gap is wide enough to get a hacksaw blade in you could separate the wings and start again. If you are going to fill the gap use 1hr or greater cure time epoxy and a syringe. Edited By Rick Tee on 10/08/2013 07:06:23 Quote Link to comment Share on other sites More sharing options...
NigelH Posted August 10, 2013 Share Posted August 10, 2013 Absolutely don't cut it in half. You'll never get the spar out and the wing will be useless. Fill the gap good and proper with thin 30 minute epoxy. Be sure that it has run all the way into the gap. As it happens, I built the mark 1 version and followed their instructions, using the 5 or 10 minute epoxy that there suggested. Poor advice as the beginner modeller doesn't realise that they have no time at all before the glue gets stiff and resists movement. I ended up with a 1mm or so gap but I just filled mine in. Quote Link to comment Share on other sites More sharing options...
Rick Tee Posted August 10, 2013 Share Posted August 10, 2013 How will separating the wing make it useless? The joiner is an aluminium tube hence hollow, just put a short 50mm - 60mm tube inside it. Granted cleaning up the root ribs may be tricky but it still beats buying a new wing/kit. As epoxy cures it forms polymer chains, the longer cure time the longer the polymer chains hence stronger and more flexible. As we don't know the extent of the gap better to fill it with a 1hr+ cure time epoxy. Enough strength in the filled joint would avoid covering with wing bandage, which would require the removal of all covering around the center section and modification of the wing seat on the fuselage. Quote Link to comment Share on other sites More sharing options...
Ben B Posted August 10, 2013 Share Posted August 10, 2013 Epoxy is heavy. Not sure I would add lots for the sake of it. I would try bending the wing to see if there is any flex- if there is an ali spar there won't be. If there is no flexing I would just cover the gap with tape the exhaust gunk going in there and go flying. Quote Link to comment Share on other sites More sharing options...
SR 71 Posted August 10, 2013 Share Posted August 10, 2013 Run a hacksaw blade through it between the ribs and around the joiner tube not through it , i think with a twist of the two panels it wiill come apart, sand the epoxy of and start again, thats what i would do Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 10, 2013 Share Posted August 10, 2013 Check that the wings really are level, ie the trailing and leading edges line up within a mm or so. If that's ok and it's got the ali tube as David said and the gap is wide enough I'd epoxy wood slivers into the gap to fill it at least on the top surface, then put a strip of film or solarrim around to hide it. If the gap is left it can create a high stress point in the joiner, filling the gap will help distribute the stresses. Medium hard balsa will be fine as the filler. Quote Link to comment Share on other sites More sharing options...
Darran Posted August 10, 2013 Author Share Posted August 10, 2013 Posted by David Davis on 10/08/2013 06:28:31: Is this the new Mark 2 Tutor with tapered wings and a large aluminium tube joining the wings together? If it is, you'll get away with it. I'd fill the gap with more epoxy and cover it with wing bandage as Tony suggests. Yes it is the mark 2. I will post some pictures of it this morning. So you can see how it looks etc. Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted August 10, 2013 Share Posted August 10, 2013 Darren - Don’t worry too much, it all been done before! Also the integrity of the aluminium spar is beyond question, I’ve put this joiner to the ultimate test using Boomerang wings, (very similar!), many times, and I think they are virtually unbreakable and unbendable. The online instructions, here, do in fact suggest to use 5 minute first and then 30 min or 1 hour to join the second. I’d just place a strip of masking tape over one side and run in with 30 min from the other. Thin it nicely by blowing it in gently with a warm heat gun, don’t over do this because even this can go off very quickly otherwise. I’d make up a balsa or other lightweight spacer and slide that in with some glue. Use as much spacer and as little epoxy as possible. The temperature is the secret. I suspect you were doing this during the hot weather, under the right conditions epoxy can go off very fast indeed. In a lump, it has been known to almost go off with a bang. It starts to warm up, which accelerates the setting time, which makes it warmer, which accelerates the setting time……. We appear to be a bit stuck with a classic thermal runaway, perhaps? If you want to slow down the setting time a bit after you’ve mixed it, spread it out over a piece of plastic card and pop it in the fridge for a while. This helps to extend the ‘positioning’ time. Another trick with wings and similar is to use 30 minute throughout, get it right, and then put a couple of dabs of 5 minute on the ribs and hold together for a short while. Then carefully leave for a couple of hours to harden. This works well, too. Good Luck. PB Edited By Peter Beeney on 10/08/2013 11:16:39 Quote Link to comment Share on other sites More sharing options...
Darran Posted August 10, 2013 Author Share Posted August 10, 2013 I know where I went wrong so at least thats a start. I used 5 minute instead of 30 minute when joining the second wing to the first and the aluminium tube, missed the glue change in the instructions. This is how it looks currently Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted August 10, 2013 Share Posted August 10, 2013 Darran, Apologies for mis-spelling your name first time, it didn’t occur to me until later. I’d make something like a card spacer, perhaps, provided it slides closely between ok, with a slot cut for the ali tube and glue it in. It’s just to try and stop any tendency for the wings to flex up and down on the brace. I don’t know of course, but I think it might be possible that in time any such movement might start to cause a bending moment right in the centre there, which eventually might result in a stress fracture. But that also might be very fanciful thinking, too! If it were mine I’d personally be quite happy to do that, and I’d certainly not restrain from pulling, or pushing, maximum G when ever possible. I’d always be tempted to try and break it! I’m assuming you are now going to learn to fly, so really enjoy that as much as possible, with hindsight it will become one of the uniquely best times, you can never go back and do it again. All The Best. PB Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted August 10, 2013 Share Posted August 10, 2013 TBH Darran, I wouldn't worry too much about that. When you said "a few millimetres", well I have seen people describe a gap you get your fingers in as that! I just wanted to be sure it really was small, and it is. No that small a gap should be OK, as long as there is epoxy in there and the wing joiner is in there it shouldn't cause you too much trouble. BEB Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 10, 2013 Share Posted August 10, 2013 One option would be to mix up some automotive filler and force that into the gap. This would bind the two wing halves together and with some white tape over the top no-one would know. Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted August 10, 2013 Share Posted August 10, 2013 It's minimal!! Hot Glue squeezed into the gap and smooth it off quickly, acts as filler AND adhesive. Then white Solartrim or similar to hide Simples............................. Quote Link to comment Share on other sites More sharing options...
Rick Tee Posted August 11, 2013 Share Posted August 11, 2013 That's a pretty small gap, use a syringe and 30min epoxy, cover with either film or PVC tape. Then it's our secret, no one will ever know.... ... Oh wait this is a public forum. Edited By Rick Tee on 11/08/2013 07:16:08 Quote Link to comment Share on other sites More sharing options...
Rich too Posted August 11, 2013 Share Posted August 11, 2013 I agree with the last two posts, tape either side of the join to protect the film, and squeeze epoxy into the joint and smooth off - Rich Quote Link to comment Share on other sites More sharing options...
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