Cyclicscooby Posted August 5, 2011 Share Posted August 5, 2011 So there I was happily covering the wings on my new Bipe.... I spent ages cutting out scallops and it was looking great... . . . Then it all went Pete Tong... The ailerons stopped hinging properly, and started to lift the tape at the ends... The tissue was bending the depron... Grrrr After re-wetting the tissue and letting it dry whilst under a load of batteries, it was still the same... I ended up having to add a CF 0.5 x 6mm strip into each of the ailerons.. It worked, but looks a mess... Ace, the aileron was now straight.... But now the whole wing was bent... AAhh... I ended up having to 'slit' the tissue, so as it dried, it opened up the slit instead of pulling the wing up.. . Wahay, the wings back straight... But now the hinges are binding again... !! I pulled the aileron down and the top surface ripped along the hinge tape... DOH..!!!!! . So, now i've fixed the wings, i've a dilema.. Do I carry on and cover the fuse.. ??? Its a full box section, so shud be strong enuf NOT to bend, but I was going to cut out loads to save weight, and that might make it too weak for the tissue.... If I end up spraying the fuse, then I cant cut bits out... Doh Doh Doh..... Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
James40 Posted August 5, 2011 Share Posted August 5, 2011 Would it be better to use an epoxy and glass cloth instead of the tissue and dope to stop the shrinking? Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 5, 2011 Share Posted August 5, 2011 I'm guessing you are not using dope as an adhesive - Polycell? Epoxy/glass may be just a little heavy on a depron foam model, but you could try different tissues, I'd imagine the glossy ones from florist etc might shrink less than those usually sold for modelling but it's a long time since I used tissue on lightweight structures. Could you build a test piece - a box section with cutouts as you intend for the fuselage - to see how it goes? Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 5, 2011 Author Share Posted August 5, 2011 Cheers Guys... FG will make it too heavy James, its only 6mm depron, but i'd love to try glass n resin one day... I'm using Hobbycraft tissue, which i'm glueing on with PVA, not doped it yet, just wet it tight... A test piece is a great idea tho Bob.. I've already made a template to cut a 'trellis' type cross hatch (4 triangles pointing at each other per 7cm sq) out of the side and bottom behind the cockpit and maybe the tail surfaces as I need to get some weight out of the tail.. I'll go and try a test box, but i'm not gonna wet it, just dope straight off, as the dope seems to tighten it less.. Thanks chaps.. Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted August 5, 2011 Share Posted August 5, 2011 when i do tissue on sheet balsa i dont wet it.just pull it tight and dope it with a 50/50 mix with thinners. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 5, 2011 Share Posted August 5, 2011 I think if you used dope you would end up with a large blob where once a very nice model sat.... How about very light glass cloth & water based PU resin like Poly C...I think anything like tissue will shrink as soon as it gets wet..... Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 5, 2011 Author Share Posted August 5, 2011 I hadn't thought about the dope melting things.. !! I presumed it'd just go ON the tissue, but I suppose it will go INTO the tissue, and hence touch the depron... MMmmm I've never done glass cloth... Where do you get it from..?? Halfords..?? I know my local model shop doesn't do it.. And also, more importantly, Poly-C. ??? I presume Halfords dont do 'model plane safe' resin.. LOL.. I presume, once covered in FG, you can just spray it with normal paint..?? Afterall, i'm only covering it to get some colour.. Well, i'm gonna go build a test piece of depron box, and try the dope, just incase it works, but looks like a trip out is needed... Thanks for the advice guys.. Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted August 5, 2011 Share Posted August 5, 2011 POLY-C Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 5, 2011 Author Share Posted August 5, 2011 Thanks Tim.. Lookin now.. Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 5, 2011 Share Posted August 5, 2011 Lightweight glass cloth This is about the lightest I have seen at 17g per sq m....25g per sq m is more commonly available here & here. Obviously the resin will add a bit of weight too but the water based resins are not too bad....epoxy resin will probably be OK on depron but not the polyester resin you would find in Halfords. Both resins are, I would suggest, too heavy for such a model as yours..... Good luck...& let us know how you get on!!! Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 5, 2011 Share Posted August 5, 2011 I have used 1/2 oz glass cloth with dilute PVA on the foam wing surfaces of a small (30"ish) model, with water soluble varnish (Ronseal acrylic? Dark Mahogany) also working well with tissue over balsa - similar to PolyC but cheaper and with the dark wood colouring, very refined! BTW - the wing mentioned above survived a terminal dive from 100' and it's just styro with a balsa le and te, covered in glass and pva. Edited By Bob Cotsford on 05/08/2011 12:28:55 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 5, 2011 Share Posted August 5, 2011 PS if you only want some colour why cover it at all.....just use water based acrylic paint...or even marker pens...(water based obviously.....solvent based pens will destroy the foam...) Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 5, 2011 Author Share Posted August 5, 2011 I had thought about paint, but i'm rubbish at it, so i'd have to hand it over to Paul, who has a nice gun n compressor... I was trying to keep in 'in-house' without employing Husbands... Also, if I start cutting holes out the rear to save weight, it'll need a covering, but I didn't realize this until it was built.. Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
andy watson Posted August 5, 2011 Share Posted August 5, 2011 poly C and glass cloth. No probs Quote Link to comment Share on other sites More sharing options...
Erfolg Posted August 5, 2011 Share Posted August 5, 2011 I am struggling to understand what the issue really is. I assume that you have hinged the surface to the wing with something other than tissue? Although I am not a particular fan of tissue, I know it works. If you are using tissue paper purchased from a card shop, it is not anywhere as near as good as Modelspan. I am so positive on this because, I have had my own difficulties with tissue paper. Yep, I am the one who bought a packet from the card shop. It will stick with PVA watered down, not as good as Modelspan though. With respect to glass cloths, in comparison to tissue. There is none, glass cloth is far better, to the extent, there is no sensible comparison. There is strong support for poly C on this site. I personally am a fan of WBV, and to date cannot see the difference to WVP. The more brands I have tried the more they seem the same, just the price varies. That is other than the high contact trade WBV, but I do not want really hard varnish, resistant to high heel shoes, I want a tough flexible coating that adheres well to the substrate, no brittle cracking wanted here. Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 6, 2011 Author Share Posted August 6, 2011 Hi Erfolg.. The issue is, I want colour on my plane.. I havent any paint that'll work, plus i'm rubbish at spraying, so tissue, which I have plenty of, was the next best thing.. I only PVA (Neat) round the edges, not all over, then wet to stretch, THEN dope I havent doped it yet tho, just wet it.. The tissue (Hobby craft variety - as its all I can get locally) once wetted, is tightening so much that it bent the ailerons into Banana's, which in turn is causing the proper hinge tape to separate at each end.. Not helped by the wing also bending, just slightly, but enuf.. To fix it, i've had to retro fit CF into the ailerons and 'slit' the paper to reduce tension... I tried re-wetting and loading the wing with weights, but it still bent, hence the drastic slicing.. As far as the rear end goes, I want to cut the 'solid' 6mm depron sides and belly into a lattice to reduce weight, BUT, after the wing issues, i'm concerned that the 'trellised' rear end will distort once covered.. I appreciate FG is ace, but I havent got any here and now, plus i've started tissuing, and it'd ruin the plane if I were to remove it... NEXT time i'll have a go at FG, once i've got hold of some of this wonderful Poly-C.. but for now its tissue troubles... Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 6, 2011 Author Share Posted August 6, 2011 This is what im using.. http://direct.hobbycraft.co.uk/products-HobbyCraft-Pack-of-Five-Dark-Blue-Tissue-Papers_244183.htm I know its not 'proper' model tissue, like this Japanese stuff I keep hearing about, but its all I can find locally.. Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
Erfolg Posted August 7, 2011 Share Posted August 7, 2011 Cyclic I suspect that your tissue is similar to that which I have purchased. The reason being similar the nearest model shop that stocks Tissue being a 60 mile round trip. The fuel costing more than the tissue, which is true for much of the bits and pieces I use. I found, and I think Richard Bond? found that it is so impermeable, that dope would not wet out the paper (dope and foam are a definite NO-NO). The same is true with watered down PVA, here it is an advantage. The stuff I purchased did not shrink, so there are differences. I have a model which needs finishing with card shop tissue, but I have no enthusiasm, as it is not esy or nice to work with. Quote Link to comment Share on other sites More sharing options...
Cyclicscooby Posted August 7, 2011 Author Share Posted August 7, 2011 Yeah, that sound about right Erfolg... I had thought about wetting it on the bench, than putting it on the plane, but that'll end up a creased mess... I think I may have found the answer, althou it makes everything mentioned, redundant.. (Sorry guys) I found some foam safe spray which matches the orange, so may end up just using that after the latest fiasco... See the build thread for more.... Still, you've all given me great advice regarding FG, so i'll definately be giving that a go on the next foamie.. Thank loads... Luv Chrisie.. xx Quote Link to comment Share on other sites More sharing options...
TonyS Posted August 7, 2011 Share Posted August 7, 2011 Chrisie, Really sorry to see the troubles you've had. You have my sympathy. I'm hopeless at painting. So bad that I'm booking myself onto an airbrushing course shortly. There are paints that will go straight onto foam. I find the problem is that it looks OK but if you need to mask for another coat, anything you use simply pulls the first coat of paint off the foam leaving it a real mess. I use very lightweight glass cloth and Poly-C on nearly everything these days. For the really light foam models it really adds strength and stops scuffs and dings appearing. It's also a bit easier to paint. I've never had a problem with weight as I generally only cover the forward and bottom of the fuse and the leading edge and underside of the wings if weight looks critical. The two big probs are that if the model has ay colour or decals on clearly you can't then put the glass on and second if the foam has detailing such as panel lines or rivets these are lost. Small price i think but it's personal choice. Quote Link to comment Share on other sites More sharing options...
Shane Sunday Posted August 11, 2011 Share Posted August 11, 2011 Tear that stuff off the wing, sand it smooth again and get yerself some POLY-C. Lay down the tissue and apply thin layers of Poly-C using a hair dryer in between coats to dry it. Jobs a good une. I've done it this way lots of times to great effect. Quote Link to comment Share on other sites More sharing options...
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