Tim Kearsley Posted May 14, 2012 Share Posted May 14, 2012 Hi all, I could kick myself - VERY HARD!! I was moving some books at the weekend, and, bearing in mind that we moved house just before Christmas, I still have a couple of the models indoors (until the garage conversion to my workshop is complete). I dropped a book, and heard a crack. It was the tailplane of my lovely e-Flite DHC Beaver - only flown three times so far. The port tailplane half had snapped where it met the fuselage and was held in place by mostly covering film and the elevator joiner wire. How would you tackle a repair? There's obviously not much gluing area, though it does fit back into place quite snugly. I just feel that it needs a bit more strength to withstand the aerodynamic forces. Any thoughts anyone? Cheers, Tim. Quote Link to comment Share on other sites More sharing options...
BB Posted May 14, 2012 Share Posted May 14, 2012 Drill small pilot holes for 'cock tail or carbon rod' sticks. Insert, align and glue with Epoxy. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 14, 2012 Share Posted May 14, 2012 BBs idea is a good one Tim.....certainly for smaller models..... Can you get in there after gluing the parts back together so you can re-inforce the joint externally....for a snapped spar gluing some strips of wood either side of the join would be a good idea.... Maybe a pic or two will help with the suggestions!!! Quote Link to comment Share on other sites More sharing options...
BB Posted May 14, 2012 Share Posted May 14, 2012 Chris's advice is correct. My advice was based on Google pic. Perhaps 'champher' out the slot that the tail plane snuggly already fits. Add fillets and sticks and exopy. It conceals the repair and adds strength that wasn't there. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 14, 2012 Share Posted May 14, 2012 Chris?? Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 14, 2012 Share Posted May 14, 2012 Consider yourself reasonably fortunate, Tim - my Beaver was at about 50ft when the starboard half of the stab decided to part company!......... .......which resulted in this: The wings are now repaired but the rest is awaiting attention. The stab seems to have an inherent weakness laterally, with only the l/edge and trailing edge spars for support. I intend to strip back the covering from the remaining stab, tunnel into the fus and insert bracing spars through and through, glued to the rear of the leading edge and front of the t/edge. A couple of inches either side should beef it up considerably. As BB suggests, something like 2mm carbon - or even a barbecue skewer - should do the trick Great model - it really should be flying, not sitting in the hangar......... Pete Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 14, 2012 Share Posted May 14, 2012 It does look a less than brilliant design.....maybe a full length spruce spar could be "let in" to the tailplane to help beef things up a bit..... Quote Link to comment Share on other sites More sharing options...
Broken Prop Posted May 14, 2012 Share Posted May 14, 2012 Gulp! Looks like I need to start excavating into the tailplane of my one. I have just finished reinforcing the undercarriage legs, which were bent in one of my more enthusiatic landings. Thanks for the info guys. I agree with Pete, it is a great flyer and does not deserve to die young. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted May 14, 2012 Author Share Posted May 14, 2012 Thanks very much chaps for the replies. Blimey Pete B, sorry to hear that your tailplane failed in flight! I hadn't realised that there was any inherent weakness there. In my case, the joiner rod which joins the two elevator halves has kind of kept everything together. I had thought of the "cocktail stick" technique (indeed, have used it before) but without dismantling things further I haven't got much space to work in. I wondered if re-gluing the mating surfaces and then adding a balsa fillet underneath the tailplane would be strong enough? Probably not I suspect. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 14, 2012 Share Posted May 14, 2012 I'm not familiar with the model but I'm assuming we're all familiar with the need to avoid cutting into the surface when removing any covering necessary to glue the tail into place? A very small score in the tail surface can cause a potential failure point under flight loads. This type of failure would be typical of that error although I'm not suggesting that the design/materials may not have caused this particular failure. Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 14, 2012 Share Posted May 14, 2012 It certainly crossed my mind as a potential cause, Martin, but I did take care to use a new blade and keep the cut as light as possible. However, I've now changed my technique and use the point of a soldering iron to score alongside the line. Pete Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 14, 2012 Share Posted May 14, 2012 I tried that once but found it marked the wood (although it was a dent more than a cut) so I went back to my previous rather freehand method of teasing the covering away from the wood with the tip of a new scalpel blade and cutting from inside out. It's very difficult to get a straight cut like this so I aim for a cut line just inside the fuselage line and tidy it afterwards with small scissors. Quote Link to comment Share on other sites More sharing options...
Glasshopper Posted May 14, 2012 Share Posted May 14, 2012 one of the best tips on this site for removing film before gluing is: lay some electrical insulating tape along the line of the material you want to remove start to peel back the covering starting with a small nick using your blade and then simply pull back the covering. It peels off straight along the tape without any more cutting. Quote Link to comment Share on other sites More sharing options...
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