Skip to content

117. Covering – Monday to Wednesday

03/07/2014

The next two weeks will be spent trying to complete the covering of the wings. I’ve joined Theo in Dorset and on Monday we dove straight into the task, working a 12 hour day. At the end of it, we’d cut out the fabric for one wing and got all the tail surfaces and centre section wrapped.

Where the fabric would come into contact with metal (such as the leading and trailing edges) tape is wrapped around the metal to provide some protection against chafing. We are using scrap offcuts slit into 25mm (1in) wide strips.

We’re also following the advice of TVAL and applying tape to all the rib caps using modern cement. It may not be strictly original, but it ensures no colour from the wood preservative leaches through into the fabric (the wood would not have had nay treatment originally, since the aircraft wasn’t intended to last more than a few months). It’s very straightforward, but the approved cement is not much fun to use; it goes off very quickly indeed, so you have to work very fast and accept that the application tool (an old kitchen knife in this case) and the spout of the tin become completely encrusted with the sticky, gooey stuff. It takes for ever to clean everything up when you’re done.

On Tuesday we worked an even longer day – right through until 2300. At the end of it, we’d sewn the leading and trailing edge seams for one wing, water sprayed and doped the rudder, and finished the hand sewing of the two elevator flaps.

 

Theo's living room taken converted into a fabric sweatshop where sewing is going on at unsocial hours, and at slave labour rates.

Theo’s living room taken converted into a fabric sweatshop where sewing is going on at unsocial hours, and at slave labour rates.

Perhaps the major achievement was to get the wing seams sewn, since it took most of the morning to work out exactly how to mark the positions of the trimming cuts, the tacking seam and the folds for the balloon stitch. It doesn’t sound too much when you’re writing it up afterwards, but the heart-searching, checking and rechecking took most of the morning before we finally had a plan in our heads and took scissors to linen. the result looks great though. Of course at this stage it’s just a slightly loose-fitting sock draped over the wing structure, and we won’t know if we’e got it right until the tautening dope is applied, and we can’t do that until Mike, our inspector, has signed off the wing structure, but it certainly looks good so far.

The rudder got sprayed with specially-delivered demineralised water and left to dry. It immediately shrank, but relaxed a bit as it dried. This was exactly what we were expecting, and once it was bone dry we applied the first coat of tautening dope. The fabric goes slack straight away, but starts to tighten as it dries, and the trick is to get it just tight enough and no more. There’s still a little bit of slackness in some areas, so we’ll see what it looks like in the morning before applying the second coat.

The hand sewing is very tedious, even though the stitches are surprisingly far apart (up to 1/4in or 6mm). The edges are folded under so that the stitches go through two thicknesses, and I found it best to position them using masking tape; the actual sewing involves a baseball stitch with a locking knot every ten stitches or so. We finally stopped when Theo had run out of swear words.

On Wednesday I spent much of the day in Hampshire, but Theo made good progress on the tailplane, with the fabric cut out and machine stitched by the time I got back. We’d applied two coats of dope to the rudder the evening before, but when I left in the morning there were still some wrinkles. However by the time I got back the wrinkles had miraculously disappeared. In fairness, this is what everyone said; it carries on tightening up for weeks after application.

I got out the book and started to find out how to carry out rib stitching. This is waxed cord which ties the fabric to the ribs to stop it being sucked off the frame by aerodynamic forces, and requires a combination of reef knots and modified seine knots – and an ENORMOUS needle to thread the cord through the frame from side to side. In fact, it proved pretty straightforward, and you then have to dope tape over it to seal it.

At this point we came across a possible complication. Dope comes in two types – tautening and non-tautening. So far it’s been the tautening dope we’ve used on the fabric, and it’s perfectly clear, but the non-tautening, although nominally clear, contains a small amount of tan colour to make it easier to see where it’s been applied. On most aircraft this is fine, since one will be applying a colour coat on top, but ours will generally remain clear, and when I applied it to the rib tapes the tan colour was just about visible.

Advertisements

From → Building

Leave a Comment

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: