Willyuk Posted November 3, 2014 Share Posted November 3, 2014 So, I popped out in a break in the weather to give the Rare Bear an outing. This jobbie flys like a brick and is a devil to get airborn off grass (especially long wet grass). Anyhow, found I left the important bit of tube to allow me to fill her up through the valve, so off with the cowl. Three flights in, the nerves were settling down and I was getting the confidence back, then Wallop, lets turn right shall we. I could see something flapping on the wing and thought that the aieleron had come loose. Anyhow, I managed to get back to the strip and put her down. Ok chaps, what did I miss in the preflight? Could I have foreseen this? The good news is that there is no damage Quote Link to comment Share on other sites More sharing options...
YakMad Posted November 3, 2014 Share Posted November 3, 2014 I have had pieces of film pull off in flight nothing as dramatic as yours, its makes a racket flapping in flight, be thankful its a fully sheeted wing and no loss of lift as a result. I don't think you could have foreseen this unless you are going to start pulling at every joint on the film before flight. Quote Link to comment Share on other sites More sharing options...
Jon H Posted November 3, 2014 Share Posted November 3, 2014 i had this happen to me once on a model I bought from a club mate. In my experience it comes from the covering being stuck round the edges and then heat shrunk with a heat gun in the middle. This method gives a lovely finish with no scuff marks from the iron but will cause the issue pictured if the leading edge begins to lift as air gets in and the thing inflates like a balloon. The problem can be controlled by making sure the covering in the middle is ironed down to the wing, and also make sure the join in the covering is not dead on the leading edge but slightly further round under the wing. this should help limit the chances of air getting under it. all joins can also be painted over with clear fuel proofer or even a thin smear of epoxy to help keep the edges down Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted November 3, 2014 Share Posted November 3, 2014 Looks like it could well of started from the edge of the air intake on the wing root, if there was a chink in the covering the adhesive could become compromised by fuel deposits seeping under the covering over time and the prop wash would pull at the corner and tear it back that way Edited By Dave Hopkin on 03/11/2014 15:20:18 Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted November 3, 2014 Share Posted November 3, 2014 hello willyuk...I would suggest that the foam was damp/ish with moisture that stopped the glue getting a proper hold...and as mentioned-tacked at the leading and trailing edge........only-poor quality control wherever it came from........remember the large sopwith camels that were falling apart in the sky? ...built with timber that had weavils in...that once they had finished their lunch caused structural failure and wrecked model's....prob same place or next store... ken Anderson...ne...1...... quality control monitoring dept. Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted November 3, 2014 Share Posted November 3, 2014 **LINK** and balsa loc Quote Link to comment Share on other sites More sharing options...
Willyuk Posted November 3, 2014 Author Share Posted November 3, 2014 There was no sign off fuel seepage and it is a sheeted wing so no foam in sight. I guess a loose corner then the air got under it. Anyhow fixed now with a good application of Balsaloc and a hot iron. The rest seems reasonably well stuck down, I will keep a careful eye on the other wing now! Quote Link to comment Share on other sites More sharing options...
Levanter Posted November 3, 2014 Share Posted November 3, 2014 A few weeks ago I asked about covering over sheeting to get that mirror finish. Like Jon says, if you shrink the panel with a hot air gun it looks beautiful but not much adhesion if any. Somebody suggested very lightly rubbing the film with a soft cloth while still hot from the heat gun. I tried this and it gave very good adhesion without spoiling the finish. I tend to iron the perimeter for at least 10mm where I can. The aircraft looks faster than any of mine though! Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted November 3, 2014 Share Posted November 3, 2014 One of our club members took off with his very well flown Harmon Rocket,. AFter a couple minutes the model seemed to go out of control but he managed to get it back on the ground in one piece. The covering had come off the top of the right wing and that is not a foam wing. He was very lucky have a model left Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted November 3, 2014 Share Posted November 3, 2014 I think you are right Willy - the corner has lifted and the wind did the rest. The problem is of course that once even the smallest corner of the covering lifts it ain't going to get any better - as we all know there is only one way this is going to go! Fortunately - most of the occasions this happens we manage to get it down with just a loose corner to fix down - I reckon you were a bit more unlucky - possibly aggravated by the centre of the film not being glued in place as has been suggested. BEB Quote Link to comment Share on other sites More sharing options...
Willyuk Posted November 3, 2014 Author Share Posted November 3, 2014 you wouldn't believe the effect that the flapping film had on the aircraft. I needed full left aileron to keep the wings level, so my flight path back to the landing area was interesting. I could have done with some bicycle clips! To be honest, as a relative novice, I feel that coping with the issue has made my feel more capable of dealing with problems that arise. A good learning experience. Mind you I have had a few of those - when does it stop??? Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted November 3, 2014 Share Posted November 3, 2014 Posted by Willyuk on 03/11/2014 19:41:56: A good learning experience. Mind you I have had a few of those - when does it stop??? When you go to the big flying field in the sky! Actually - I believe that they still have them there as well! BEB Edited By Biggles' Elder Brother - Moderator on 03/11/2014 20:40:52 Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted November 3, 2014 Share Posted November 3, 2014 Well done Willy. All that B practice comes in handy at times like this! Keep it up! Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted November 3, 2014 Share Posted November 3, 2014 I had a very fast delta wing pusher prop. It was EPP covered with coloured tape in stripes, yellow and red. The motor mount sheared off while throttling up after a low pass, and the prop with the motor still under full throttle going I don't know what revs hit the trailing edge. What I saw was a model that suddenly lost the ability to accelerate, but just as suddenly changed colour to plain white as the prop stripped the tape and tangled it into a small knot round the prop................ Quote Link to comment Share on other sites More sharing options...
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