Another quite brief entry as we’ve been very busy Bluebirding of late. The verb, to Bluebird… we conjugate it all day long. The old girl is getting very exciting nowadays as lots of parts begin to come together but we’ll revisit the small matter of our big tin boat in due course because from ordering material and hardware to putting rivets or bolts into a finished part can often take months and we’ve a lot meeting at its natural confluence at the moment so we’re grabbing only small bits of Barra’ time here and there but the tail is almost done so small jobs suit us just fine. Apart from some minor snagging, about the only outstanding items on the tailplane are the fairings where it marries to the sticky up bit, which we can’t do until it’s bolted up there on a more permanent basis, and the portside leading edge.
Lest we forget… The severed end of the tailplane on its back as Aerospace Rob stands by, drill in hand, awaiting the word to go. This is its underside and if you look closely you can see the nature of the failures that separated it from the rest. Basically, the middle stopped and the ends carried on. The front spar (nearest Rob’s legs) failed in compression and bent aft through 90 degrees whilst the ends of the tailplane swept forwards. Then the rear spar failed in tension so what you see is the snapped ends of both spars bent in towards the centre until they almost touch. That’s all mended now, except for the leading edge, which you may remember wasn’t too bad.
It didn’t take long to get the worst of the trouble out of it but it’s always the same. It’s easy enough to make it look right but then you try to pin it on all sorts of horrid things happen.
It’s never as simple as it might appear.
Looks OK, doesn’t it. Big wow-factor but the reality is that it won’t work until brought within about an eighth of an inch everywhere and in the condition seen above it’s only really accurate to the nearest half-inch. But we’ve been on it and it’s a case of an hour here and an hour there. It needed lots of welding and a fair few patches and each one must be carefully shaped into a hole that we enlarge around an area of damage then weld the graft into place, the welds are next dressed down to the thickness of the native material then everything is carefully hammered to be rid of the natural weld-shrinkage without stretching it too far. In many instances we inadvertently leave small inclusions in the welds as it’s virtually impossible to snag them all. This is old material, after all, and it only takes a speck of corrosion or dirt left in the weld and the job will soon begin to crack around it whereupon there’s nowt for it but to grind, re-weld, grind again and start anew with the hammers. Then there’s all the stretching from smacking a mountain that may not be apparent until you pin the panel on then suddenly you find you have way more panel than you thought you had. At that point it’s time to whip out the hammers and blowtorch for a spot of shrinking – something, I am pleased to say, we thoroughly understand these days and are able to do very effectively on this horrid old tin.
The result… our leading edge is now beginning to take proper shape.
It still needs a patch or two but they’re small ones that won’t pull the shape about and at the moment it’s on MDF formers so we can batter it into submission without risking the originals but it’s certainly giving in.
If you look at the right-hand end of it you can see where there’s a patch to go in. We mark out the area to be sacrificed with a Sharpie then hatch it in so there’s no mistake as there’s a secret language of Sharpie marks in our workshop to indicate where a crack has been spotted or an unwanted rivet hole is to be welded up. Still others indicate an area to shrink or stretch but the cross hatching means only one thing. Chop it out and consign it forever to the BOOB box.
For those who’ve only just tuned in, BOOB stands for Bits of Old Barra’ and is an evolution of LOOF, which is in turn a noun invented by the Bluebird Project inspired originally by some fool museologist appointed by the HLF as a so-called ‘expert’ who told us that there was no way to rebuild our tin machine without considerable ‘loss of original fabric’. Had they bothered to read our conservation management report as prepared by one of the UK’s top people they’d not have been so thick, but there you go…
Notice that patches are always as circular or semi-circular as we can make them. There’s nothing worse in this world than a welded ninety-degree corner for pulling horrible stresses into a panel.
This leading edge section is much better than the one on the other end of the tailplane where we quit when it became a duel to the death with the metal but we understand this material and how to work it so much better now so this side will not suffer the indignity of the dreaded filler – phew! All you see over here is bare metal.
We’ve also begun the reassembly on another project within our project. Remember how aerospace Rob spent weeks and months stripping an assortment of tailwheelery bulkheads?
Well at last it’s reached the ‘putting back together’ stage and it’s not the nightmare that it first appeared.
First job was to get all the paint and grime off it so it got chucked into the Harry Potter stripping bath. For those unfamiliar with this particular indispensable asset, many moons ago (2006 to be precise) Chemettal-Trevor arrived with some gloop in a drum that he assured us would strip paint forever if we mixed it with water and simply believed... We didn’t believe at all; well you wouldn’t, would you. Yet in 2014 it’s still going strong and we have no idea why or how.
You simply splash the painted object into the mixture, give it a couple of days then brush all the paint off to leave gleaming metal – it’s all very mysterious and you can wash your hands in it too with no ill effects.
Having said that, it’s still a slightly grubby job and poor Lou drew the short straw on this one.
It’s OK really because Lou is eminently suited to meticulous detail work as she mends things in museums professionally so a rotted sheet of scabby aluminium was no obstacle. Hayley, on the other hand, always has a surplus of mischief and energy so getting loose with fire and a slapper to shrink the worst of the damage from the newly cleaned panel suited her very nicely.
The result – we have a solid starting point for the rebuild of our tailwheelery.
OK – it’s a bit crusty but it’s clean, mostly there and fairly flat – as good as if we’d just had it delivered brand new from the Fairey factory and unwrapped it only yesterday so far as we’re concerned. The reason the upper corners are rotted is because it has steel doublers either side and guess which metal won when it was left in the weather for a few decades. Nothing we can’t fix, though, because there’re no rules where corrosion is concerned and often no rhyme or reason as to why some bits fizz to dust and others stay in mint condition, which is why we have a couple of spare upper corners from another plane.
They’re not exactly gleaming either but they’re not too bad and we have the rest of the bulkhead that they came from to use for grafts so we have an entire and wholly original F-26, now all we have to do is assemble it. The great thing about it is that there’s so much gubbins to add to it that once it’s built you can hardly see anything of this flimsy panel at all. In fact, it seems that all it really does is provide a canvas onto which all the important parts are painted.
Here it is with some of the parts laid on top – see how the innermost skin of the bulkhead is steadily disappearing and we’ve hardly begun.
There remained one possible obstacle, though. What if the thin, springy bulkhead just wouldn’t weld?
In fairness, we’ve yet to find a material that won’t weld despite many learned individuals assuring us otherwise but some are inordinately difficult and this has some very peculiar corrosion going on due to the steel doublers. Nothing for it but to get chopping and grafting and what a pleasant surprise! Not only does it weld easily, even the corroded sections flow nicely with the corrosion products floating off on the surface of the weld pool. We also grafted half an attachment angle onto another example that was missing its end. These angles attach the aftmost ends of fuselage skins to the tailwheelery and we have numerous examples so finding a couple of decent examples just meant a dig in the box that Aerospace –Rob has been tossing fragments of scrap into for some weeks.
Here the ends have been trimmed ready for the application of hot metal glue and the angle has been returned to a state of reasonable straightness. Notice the extreme ragginess of the bulkhead in this area too. For this reason it became the site of our test repairs to prove-out the processes so we could be happy in the knowledge that, with much painstaking work, it’ll all mend.
All the mending in this shot is up the left-hand side and it looks pretty good but there’s still much to do. If you look closely you can see some higgledy-piggledy rivet holes not yet welded up and vanished and a short stretch that hasn’t been welded at all because there’s a little too much corrosion on the other side and another graft is needed there. Here’s the reality of it.
And the trick is to let in the grafts in such a way that one positions the next. Notice how the piece we’re inserting here passes right through the middle of the circular hole in the upper right-hand corner. It didn’t have to and doing so made work in welding the inside of the circle without blowing the edges away but that circle provides a perfect reference not just for positioning the graft but also for gauging the weld shrinkage.
Remember what I said about one graft positioning the next… well if you look to the right of the circular hole in the new bit you’ll see that there’s still corrosion holes to be mended but one thing at a time and the important thing is it’s going to work so pop back next month and we ought to have it looking ready to fly.
Oh – and do us a favour too, please pop over to the Bluebird Project and have a look at what we’ve been doing there and if you like what you see and have a spare tenner would you be kind enough to tip it our way because we’ve been getting all expensive of late and we’re skint!
Cheers, all… and thanks.