Covering a sheeted surface in tissue and dope.

[David Davis]

I am building Dr Walt Good's "Big Guff," one of the very first radio controlled model aeroplanes which first flew in 1938.

I have built the fuselage which is completely covered in 1/32" sheet balsa. I am toying with the idea of covering the fuselage in coloured tissue but have not used this method for nearly sixty years so I have a few questions to ask the cognoscenti.

1. I am advised that I should give the fuselage in 2-3 coats of full strength nitrate shrinking dope before attaching the tissue using 50/50 dope and cellulose thinners but should I use a sanding sealer first?
2. I have a collection of Hamilton Perfection brushes which date from my time as a painter and decorator. Should I use one of these to apply the dope or is there a better alternative?

I will be using Esaki Super Flite tissue from Mike Woodhouse of Free Flight Supplies and I intend to fuel-proof the structure using a varnish.

I am also building a "Sharkface" and I'm going to try using tissue over doculam for its wing. If it's successful I may even cover the flying surfaces of the Big Guff in the same way.

Picture of the Big Guff's fuselage below. It's 5'4" long with a maximum depth of 10.5" and a maximum width of 6.5". (163 cms x 27 cms X 17 cms.)

[Andrew Calcutt]

I would use sanding sealer on the balsa first,wet the tissue as you lay it on,I use a hand spray.I buy cheap disposable brushes,I thin the dope 50/50 using thinners 2or 3 coats.Take your time rub down between coats and should be ok.

[bert baker]

I would have a practice on a scrap piece of balsa,

Its quite easy to put to much dope on and can start to ballon up

[J D 8]

I made my Matador's fuzz the Andrew Calcutt way nearly fifty years ago and it is still going strong. Very much doubt it would still be around with just tissue for covering.

Using neat dope on the 1/32 would result in a lot of extra weight and a chance of some warping of the structure.

[David Davis]

Thank you for the responses so far gentlemen but it has prompted a few more questions.

1. After applying a coat of sanding sealer do I then apply the tissue and 2-3 coats of thinned dope or do I apply 2-3 coats of thinned dope first then attach the tissue to the substrate using thinned dope?
2. What is the Andrew Calcutt way JD8?
3. Weight considerations. Do I use the sanding sealer full strength and subsequent coats of dope thinned 50/50?

The alternative to using tissue would be to use Solartex which weighs 95 grammes per square metre. Esaki Super Flite only weighs 21gsm.

[Nigel R]

in my (fairly limited) experience;

1 sanding sealer,

2 very light sand with fine grit to smooth off any lumps

3 repeat above two steps if needed

4 tissue attached using 1 thin coat of non shrink dope

5 several coats of shrinking dope to suit

6 transfers and all that stuff

7 several coats fuel proofer

 

"Esaki Super Flite only weighs 21gsm."

It'll be a bit more when you've got fuel proofer and paint and dope on there, surely?

Standard non vintage film is around 65g/m2 (not that you'd use it on this, although I probably would).

'Tex is easy, although a bit pricey, but, you don't need to buy dope or very much fuel proofer.

Edited By Nigel R on 06/11/2019 09:23:39

[FlyinFlynn]

Take a look at http://www.ffscale.co.uk/comp7.htm There is a wealth of good info contained within that site....

[David Davis]

Posted by Nigel R on 06/11/2019 09:23:05:

" ... "Esaki Super Flite only weighs 21gsm."

It'll be a bit more when you've got fuel proofer and paint and dope on there, surely?

Standard non vintage film is around 65g/m2 (not that you'd use it on this, although I probably would).

'Tex is easy, although a bit pricey, but, you don't need to buy dope or very much fuel proofer."

Edited By Nigel R on 06/11/2019 09:23:39

Thanks for the info Nigel. I don't intend to use paint on the model, I intend to use coloured tissue so there's a weight saving there and tissue and dope is not that expensive.

As for Solartex I've got quite a bit in stock but most of it is reserved for other projects, if I live long enough! However, I have 2-3 metres of Solartex which is either Dark Green or Olive Drab for which I have no immediate purpose!

[Martin Dance 1]

I agree with Andrews post (post 2). However bearing n mind that you used 1/32 balsa and presumably joined 3-4 sheets edge to edge using shrinking dope could lead to problems. I would be inclined to use either banana oil or a non-shrinking dope for attaching the tissue and subsequent coating of the fuselage. Again all well thinned at least 50/50 or even thinner and use more coats as a consequence.

[Peter Miller]

What we used to do is apply the dope to the wood and allow to dry Then lay on wet tissue (not dripping but wet through) getting any wrinkles out. Then apply thinners. Putting the wet tissue on newspaper dries it out to perfection.

The thinners wets the dope and draws it into the tissue. Then once this has dried (It will leave lots of white splotches) apply normal thinned dope, at least two or three coats.

You will end up with a shiney coloured finish.

[Andrew Calcutt]

I always use none shrinking dope on sheet.another thing don't over brush it,it dries quickly just brush it on quickly and leave it alone.

[David Davis]

May I firstly express my thanks to everyone who has offered advice on using tissue and dope to cover the fuselage of my Big Guff. I was simply waiting for my pension to be paid before ordering the materials but yesterday morning, before I'd even had breakfast, I had a Eureka moment! It requires a little explanation so here goes.

My Uncle Geoff was the man who helped me build my first model aeroplane. He was married to one of my mother's four sisters. He encouraged me through the second and third build but died of cancer in 1961. He was only thirty years old. He had worked as a draftsman and before he died he gave me all of his models including the fuselage of a double sized Tomboy and the plans he had drawn up. Among the models was a standard sized Tomboy which I flew free flight powered by a Mills 75 diesel.

Spool on thirty years and I finished his big Tomboy in the colours of his small one, yellow fuselage, red wing and tailplane with red trim. In fact it's had three fuselages. The first one was his own but the balsa was very weak so I built a second fuselage using cyano throughout. This disintegrated in a crash caused by pilot error: I was very inexperienced at the time so I built a third fuselage. The third fuselage was broken beyond repair when I put the model into a tree; again I was very inexperienced at that time but I still have the plan, and the wing and tailplane are in a box in my workshop waiting for me to build a fourth fuselage!

I'd covered the first fuselage in yellow nylon and the wings in Vintage Red Solartex. The second and third fuselages were covered in Vintage Yellow Solartex. At some stage I bought some more Vintage Red Solartex in order to carry out repairs but it was a different shade of red to that of the wing. I wrote off to Derek Hardman at Solarfilm who replied to say that they had changed the colour of Vintage Red Solartex. The more modern version is a brighter more transluscent colour but he offered me some of the old colour at a good price.

Yesterday morning I realised that I'd still got a roll of this old colour so I went down into the workshop and measured it at eight metres long! I also have four metres of ordinary Red Solartex which I'd bought to cover a Puppeteer in post-war colours but Flair ceased production before I could buy the kit and I also have two metres of "modern" Vintage Red, so the Big Guff is going to be finished in red Solartex. Perhaps two different shades of red, but red it will be! I have too many other projects to occupy my time, both aeromodelling and non-aeromodelling, so speed and practicality trump authenticity but it will be a much more cheerful sight at the flying field than Olive Drab to say the least! Once more a big thank you to all who offered their advice on using tissue and dope.

The roll on the left is the later shade of Vintage Red, the central roll is old Vintage Red and the right-hand roll is standard opaque Solartex Red. The Super Sixty is covered in the more modern Vintage Red and the Tomboy's flying surfaces and rudder are covered in the older colour. We were all much younger then.

P.S. I 'll be ordering some shrinking dope anyway. I am building a Sharkface and plan to finish the wing in tissue over doculam.

Happy Landings Gentlemen!

[Julian Murch]

May I ask a question about shrinking and non shrinking dope and thinners. I am completing a Guillows small Spitfire rubber powered model. The instructions give advice for both dry and wet tissue and I am leaning towards wet as for dry as it recommends multiple small pieces to cover the Spitfire shape.

Before tissue, It calls for the completed frames to be given 3 coats of 50:50 dope but does not specify which type. I used non shrinking dope thinned.

I had problems last year with an old Kiel Kraft Chief kit using shrinking dope it caused some of the ribs to be crushed. I used it at full strength. I am not talking about warping as the wings were held down on the board while it was drying.

My question is after covering the Spitfire with tissue should I use shrinking or non shrinking dope and should that be 50:50 diluted. Can you mix shrinking and non shrinking dope to further reduce the risk of damage.

[Martin Hodgson]

Never use dope at full stregth, it is far too powerful on models with tissue.

There are 2 types of dope- I use nitrate but you can get butyrate as well, not sure what the difference is.Each of these is available as shrinking and non shrinkg. You can mix and match shrink and non-shrink but do stick to either nitrate or butyrate.

Your KielKraft chief ribs were crushed because you used dope unthinned. Its shrinking power was too much for the structure. I learnt that one the hard way too.

When you thin dope it reduces the shrink power, I always thin dope at least 50/50 with thinners, usually more.

My techinique, which would work for your spitfire is as follows.

Sand structure. Apply a coat of thinned dope (shrink or inshrink does not matter). Sand and add another coat then sand again. I apply tissue wet, lay it on structure then using the thinners I clean the brushes in (it will have some dope in it) I attach the tissue around the edges. I then brush a 50/50 coat around the edges only, to make sure it is stuck down. Leave to dry. Wet tissue will shrink as it dries. Use a sanding block to trim/tidy the edges. I then apply a coat of thinned shrinking dope. If I am happy that the tissue is tight I can then switch to nonshrinking dope, if not then another shrinking coat.

Do remember doped surface will continue to shrink for quite a while after application.

Jope that helps

[John Stainforth]

Seeing JD8's photo of a Mercury Matador reminds me of sketch that my brother found that I did in 1965 (in blue and red biro) of our single channel RC Matador. We called it "Matador 2" because we essentially rebuilt the whole plane, beefing it right up by adding LE sheeting and covering it with nylon fabric. By it's designation "S12", it was already our 12th model aircraft. (We starting making model aircraft and other things around 1959!)

Edited By John Stainforth on 03/01/2020 04:13:27

Edited By John Stainforth on 03/01/2020 04:15:49

[Martin Hodgson]

Here is an impressive tissue covering of an entire p51 fuselage in only two pieces of tissue.

https://youtu.be/DrO-0ktP1qk

[Julian Murch]

Hello Martin

Thanks for the advice here. I have just completed the initial frames covering and sanding so will try your method over the week end I will post further news.