Wrinkles in tissue

[Snas]

Hi, I'm building my first balsa wood plane, kit #504 Supermarine Spitfire MK1. I applied the tissue to the wing, gave it a little spritz of water & alcohol, and thought things went well, but when it dried I had wrinkles in it, so I took it off and reapplied the tissue and got the same results. What can I do to remove the wrinkles? Thank you Charlie. P.S. I tried to attach a photo but was not able to!

[Chris A.]

Spitfire wings can be problematic due to their elliptical shape. As the wing is curved both span wise and across the chord, it is a shallow compound shape. Start by covering the bottom first as you can use one piece. Put glue only around the wing panel. Check your tissue to see what direction the fibers run. You want the fibers to run along the span length, not across the wing chord. Glue, spray and pin down to keep the panel from curling. Let dry.
As for the top of the wing panel, consider cutting the tissue into three pieces, span wise, you can run one strip from the front part of the fuselage rib to the tip rib and from the leading edge to the main spar with 50/50 white glue/water applied to the leading edge, fuselage rib top , main spar and front of tip rib. The second piece is from the back of the fuselage rib to the main spar to the trailing edge and to the back side of the tip rib. The third tissue piece is just from the top of both front and rear of the tip rib to cover the entire tip. Try not to pull too tight. What I did then was to pin the entire covered wing panel over Saran wrap on the build board, not pinning through the wood, but using the pins to angle clamp the wing panel to the board. Then lightly spray the entire panel with a water mist. And leave it to completely dry while clamped. When the panel is dry, check for warps.

[Snas]

Thank you very much Chris, I had applied the tissue to the top of the wing first. Tissue has been removed and I'm starting over!

[Chris A.]

I hope my advice was of some help to your efforts. Although the top of the Spitfire wing is a challenge to cover, the bottom surface is much simpler as it has no upward or downward camber from the tip to the fuselage, the wing bottom is supposed to be flat. However if you are planning to build a flying model, you will have to do some trimming to offset the torque effect from the prop which will tend to make the model roll. I use a cut strip of post it note applied to the trailing edge of one wing to create what is called "washout" which will counteract the lifting effect of prop torque. When the proper amount of washout is created by the post it trimming strip, I actually cut the trailing edge and raise or lower the cut section to make a permanent trim tab up to lock in the washout so you take out the rolling effect. If further adjustments are needed, I still use a little post it strip to fine tune the trim. I recommend the "Flying Aces" free flight club and their news letter as the members have years of building and flying experience that they pass on to newcomers and those (like me) who returned to the hobby. They have a great website. I also recommend that you build one of Guillows high wing models like the Cessna or Fairchild as they are easier to trim for flight.

[kittyfritters]

The #504 Spitfire has a strong enough structure that you can cover it wet (actually damp). This allows you to cover each wing panel with single pieces of tissue, on top and bottom, with no wrinkles. It does take a little practice, and is easier with Esaki, Japanese tissue, but once you've mastered it will become your go to covering method. There is an excellent tutorial on the method, by scigs30, on this forum. The attached photo is an example of wings (#309LC, Cessna 150) covered wet with single pieces of tissue.

[Chris A.]

The above response is correct for the current Guillows Spitfire model. My Spitfire build was a replica of the much earlier 1960's Guillow $.69 model built from old plans. Guillows changed their design and the earlier model is much lighter due to fewer formers and ribs.

[scigs30]

Here is how I covered my Spitfire.
viewtopic.php?f=2&t=3645