|Tim Saddler||26/02/2019 13:09:48|
|3 forum posts|
|5926 forum posts|
Hello Tim. Nobody seems to have answered your question yet! Very strange that the forum experts have not replied yet.....
I don't use tissue and dope on small built up wings so I cannot give a useful answer, but I think people do pin them down with spacers whilst the dope dries. No doubt someone else will help a bit more.
Most of us use iron on film for moderate size wings - the film from HobbyKing is a favourite now that Solarfilm is no longer made.
356 forum posts
If I remember rightly I have held the wing off the desk on balsa blocks and placed suitable weights on top at sensible positions above spars etc while the dope dries. I think I must have stopped the blocks sticking by having sellotape on them and moving them a little half way through. It's been a while though. Still have a lot of dope left in the workshop which I may never use again!
My last tissue covered model was an SE5a at 26" wingspan for electric power, before that an Aerographics Sopwith Camel adapted for RC.
|511 forum posts|
The method I use is to dope both sides of the wing and then pin it down using scraps of 3mm balsa sheet to keep it all clear of the board. You can use scraps of polythene bags to stop the wing from sticking to the packing pieces.
I also do this when water shrinking the tissue, I always use Esaki lite from Balsa Cabin or FF Supplies which I put on damp using dope as the adhesive. I dope the bare framework first.
I hope this helps, it always works for me and many other free flight people.
|Test Pilot||26/02/2019 21:41:50|
|2 forum posts|
I've had the same problem with lightweight structures on rubber models.
I solved it by shrinking the tissue in the normal way with a mist of water, then using non shrinking dope thinned 50/50. Never found it necessary to pin down anything but the smallest wings, but it's good advice and woldd give you even more chance of it coming out straight and true.
Since using this method I've had no problems.
Hope this helps.
|Tim Saddler||27/02/2019 08:27:02|
|3 forum posts|
Thanks for the advice guys - much appreciated...
I am recovering a rubber P30 model wings and tail that i found in the loft.
I will try Bert's method to avoid warps.
I did do an experiment with solarfilm for another model and found I still got a warp.
I suspect that the demise of "old style" gas fires where you could shrink and twist if you had any issues and only being able to use the iron to final shrink these days was the reason.
Thanks again guys
|Engine Doctor||27/02/2019 10:48:24|
2254 forum posts
Possibly not that many of us who used dope and tissue left to answer !
I haven't used dope and tissue for years now as prefer Lightspan or Airspan .
Here is what I used to do. Pin or glue 1/4 inch balsa scrap on a board to support the wing edges and keep the wing or panel off of the board. Apply thinned dope 50/50 to bottom of panel and pin to the blocks. Now apply dope to the top of the panel and leave to dry thoroughly .
If panel is very light structure then but spray with water first to shrink the tissue and pin to blocks and allow to dry . If this shrinks it sufficiently tight then apply a thinned coat of non shrinking dope to seal the tissue . If you apply shrinking dope on a very light structure and its too strong then it will distort the frame and get a "Starved horse look" Again pin down until thoroughly dry . Panel should then remain straight.
Depending on what dope you use you may have to thin it more or less as it seems to vary wildly these days as does the quality of tissue .
It might pay to make some test frames to test your tissue shrinkage and dope strength.
Hope this helps
Edited By Engine Doctor on 27/02/2019 10:49:43
769 forum posts
I've just been surfing for a small clipped wing cub builders kit & had another look at Sig, the kit & manual. In the manual, is a long spiel about what to do with a warped wing, which didn't fill me with enthusiasm for the kit, but may help Tim
"If the wing develops warps during covering and painting, it should be straightened. One good method is to spray on a thin
Edited By Stearman65 on 27/02/2019 22:49:22
Edited By Stearman65 on 27/02/2019 22:51:44
|511 forum posts|
You can avoid all of that long-drawn out process by pinning the surfaces down after shrinking and doping.
if you do decide to go the twist it out route you will be doing it a lot because the warps will always come back.
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