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137. Wing Working

05/10/2014

We’ve had a couple of days of beautiful weather and I wanted to use them to get the final coats of dope applied to the wings.

But first I needed to get the inspection hatches fitted next to the aileron pulleys. These are little sliding aluminium doors on the undersides of the wings and we needed to make the frame for them. There are no detailed drawings, but we’ve been to see the Bristol fighter at Hendon and that gave us a good idea together with the general arrangement drawing of the wing. But they are fitted in a rather crowded area; they sit on top of the compression strut and end up overlapping the slightly angled rib alongside. Then the aileron cables on the lower wings want to get into the picture as well. Still, eventually they went in okay and we can now check the pulleys and get an endoscope in to check some of the wing structure at least.

2014-09-22 Wing inspection ipening

And I was in time to catch the good weather to slap a couple of coats of non-tautening dope on the wings, tailplane and elevators.

You may remember that the wing fabric had been giving us a good deal of concern, owing to the tautening dope’s apparent inability to tauten the fabric – indeed, it seemed often to leave it slacker than it had been before it was applied.

We’ve been watching the condition of the wings ever since. At the LAA Rally it was amazing how much the tension varied, depending on the humidity and temperature. But overall, it does seem to be gradually tightening up, and I’d come to the conclusion that we should pick a good warm day and go for it, on the basis that there might not be too many good warm days to come.

So we lined all the wings up on trestles on the tarmac outside the hangar and I set to with a 4in brush. It took all day, but by the end of it, many of the remaining wrinkles seemed to have worked themselves out, and I was pleased with the outcome. It will take a day or two for the dope to fully dry out, but I’m coming to the tentative conclusion that the tautening dope doesn’t do any tautening, but that the non-tautening does.

If this seems a little confusing, let me explain. Dope comes in tautening and non-tautening varieties. Both of them will do some tautening, but the tautening dope does more tautening than the non-tautening dope. But I have come up with an alternative suggestion; that the tautening done by the tautening dope is actually less than the tautening done by the non-tautening dope, and that although both tautening and non-tautening both do a bit of tautening, the labels have got muddled up. Is that perfectly clear now?

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From → Building, Technical

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