I got a great email after the last diary. It said something like; tell whoever writes the diary to be less ‘verbose’. What a wonderful word, but verbosity is sort of the point. The format is long established in that there’s a rant first that hopefully raises a smile and occasionally goes viral. How I wish I could find Mrs. Dog Coat again, for example, to thank her for such good material, and the BBP guide to idiots has become a global standard. So I mailed this curious individual to ask why he’d say such a thing.
Apparently, using too many words is no good for people who work 24/7, 365 days a year and what they require is no-nonsense, to the point and concise information with no frills. Just how dull would your life have to be that that’s how you had to take your dose of Bluebird Project? I therefore gently explained that he’d missed the point completely and that what he ought to do is pour a nice cup of tea, coffee if you’re American, which he was, and put your feet on the desk and be transported into the workshop amongst the team. So, my American friend, this is about to go all verbose so go get the kettle on, seat yourself comfortably, and we’ll begin.
I accidentally drove a car for tetraplegic morons the other day. The missus was wanting a new car (she’s not a tetraplegic moron, by the way) so I went to the dealership where a mate of mine is in charge and borrowed an example of her first choice. It looked pretty and felt all snug and comfy so I lost no time sorting out the music, seat and mirrors and, because it was a scorching day, I twiddled with the climate control until a delightful cool breeze whispered through the cabin. With everything to my liking I set off down the road and almost immediately met a set of traffic lights. Not just those that let the traffic flow smoothly but the type designed for the non street-savvy population who must be bidden over the road every time by a flashing green man and a beeper. The lights that will waste your whole afternoon shining a dozen ways first to stop the traffic then another dozen ways so inept duck-eggs can cross the road.
The new car stalled… the engine just quit, the air-con went off and as I sat pressing buttons and swearing at the thing as the sun’s radiation roared through the glass and the temperature in the cabin climbed alarmingly. It wasn’t until I started messing with the pedals and the engine restarted that I realised it had done it on purpose. With my cool breeze once again fighting to restore the temperature I spun around, hurtled back to the dealers and demanded that such a stupid contraption be switched off at once. The salesman showed me a button and off it went. No problem, except that once I’d switched the car off and on again on purpose the damn thing developed the same fault and I had to go looking for the button every time. Imagine buying a new car that packed up at every set of lights and the salesman saying, ahh, it’ll be OK if you just twist these two wires together soon as you get in… That’s what it was like.
Deciding there absolutely had to be a fix for what I had now dubbed the ‘stall-o-matic’ system and that I’d address this particular farce at a later date I soldiered on with what was supposed to be the very latest in automotive treats – until it got low on fuel.
Now I’ve had lots of cars over the years and without exception they’ve all been possessed of a small gauge with a picture of a petrol pump and a needle that indicates in a simple way when you have lots of fuel and when you have none at all and this car was no different. But this simple indication evidently lies beyond the grasp of their target demographic because once the gauge began recording a depleted supply a little screen in front of the driver joined the party by spelling out in big letters that the tank was almost dry. I wasn’t too bothered at having my intelligence insulted by a machine until the bloody sat-nav decided to get in on the act by interrupting my music to say that what both the gauge and the little screen were trying to tell me was right and would I like it to use its superior intellect to find me a petrol station? How thick do you have to be to need this rubbish? I hit the button to cancel the onslaught and get back to the music but five minutes later it was all back again so now I had a car that stalled at every junction unless you cleared the fault and, in the interim, treated me like a five year-old.
But that wasn’t all. You see, every car I’ve owned also has small panels of reflective material mounted in strategic positions around the cabin within view of the driver in which you can observe a reflection of what is going on behind the vehicle – a most useful safety feature, I believe they call them mirrors. But the car for tetraplegic morons goes one better. The moment I selected reverse the little screen shut up about the fuel situation, and, having found something more irritating to do, proceeded to show me a crap-quality picture of what I could already see with perfect clarity reflected in the shiny things… Oh for goodness sake, I have eyes and a functioning neck!
I took it back in disgust but the salesman was prepared, sort of… the stall-o-matic system is some sort of EU directive, apparently. Oh, why didn’t you just say so in the first place? That makes it perfect… not.
It also means you pay less road tax, he assured me. So now the salesman was insulting me as much as his car just had. He wanted as much money as you’d pay for a small house before I could take it home yet he thought I’d overlook its failings to save £3.50 in road tax.
It would also reduce my ‘carbon footprint’ though he wasn’t quite sure what that actually was, nor could he tell me where all the pesky carbon was coming from when pressed on the matter.
He only shut up with his brainwashed claptrap when I pointed out that my very efficient car already does forty miles on a gallon of diesel so could he match it by putting the same amount in a bucket and painting me a line in the road forty miles long with it...
He had grave doubts about that one but I gave up anyway. You can keep on about stuff for only so long until you just say, yeah; get on with it, whatever… I’ve gone there with ill-educated car salesmen but I’m not quite there yet with traffic wombles.
The local specimens seem to have made nabbing anyone they can within half a nanosecond a sort of sport so where once you could park up, dash in to drop a letter, then leap back into the car with a reassuring nod from the local traffic warden, nowadays they pounce with digital cameras and a little printer and the deed is done in less time than it takes you to close on them and have your say. They even have a little van for those quick getaways – cowardly b’stards that they are.
The youngest went on a school trip last week to look at a lighthouse that I’ve wanted to get inside since I was a kid so I thought, at last, here’s my chance. I usually volunteer to tag along on school trips anyway because it’s yummy-mummy-tastic and they do enjoy a decent daddy but all that really happens is that I inherit all the naughty little lads that are nothing like I used to be when I was their age and I have a good laugh with them and that’s about it but this time, as luck would have it, the minibus was full so I couldn’t go. No problem, I offered to pop down in the car anyway to see what was what but when I got there all sorts of silliness had kicked off on the beach.
You see, the lighthouse stands on a small island that’s only an island when the tide comes in so the rest of the time you can get there over a narrow concrete causeway; but judging by the puzzled onlookers something had gone awry. There, on the other side, and hopelessly cut off by the rising water, was a gaggle of kids accompanied by their equally shipwrecked teachers. I abandoned the car with hazards strobing and stomped down to the water’s edge in a state of not best pleased. The teachers take them away on these trips then ceaselessly tweet and twatter or whatever it is they do about how they just saw a ragworm but the hopeless fools couldn’t do something as basically earthbound as check the tides, I’d by now decided. Resolving to find out how many times I could skim one of their useless Padeye-tabletty gadgets over the sea surface before it deservedly sank out of sight I tied my boots on good and tight and started wading. My little-un was coming back with me over my shoulder and splash would go any teacher who tried to stand in my way.
It was the wrong school trip…
By the time I’d ascertained that the upcoming ten hours on a rock was not going to cause undue distress to someone else’s school party then plodged back with my boots full of seawater and having revised my state to, somewhat disenchanted, I was just in time to see a pair of rattus-esque traffic Wombles scuttling away having put a ticket on my obviously abandoned car. Another dusting of disenchantment settled to augment the first! Was it that they were too stupid to notice all the stranded children and a small crowd of spectators? Probably. Or were they so intent on nailing their prey that they didn’t notice? Probably that too…
Needless to say, the ticket went straight back to their nest with an outraged letter and accompanying photographs soon as I got back to my office. By the way, it just so happens that I later found the correct school trip safe and sound on the beach, their teacher happily twattering away past the tide-tables on her little screen. Oops – sorry!
And so by nine o’clock that very evening my boots were still squelching as we locked up the workshop and headed home. We’ve spent the whole summer on Bluebird’s structure and nowadays the fluorescents blink off to reveal the ghostly shape of a virtually complete K7 in her boatshed under the lifeless glow of the emergency lighting. It’s spooky.
Achieving that complete shape was easy in principle and haunting to see after so many years of hard work but it’s always the same – we hang all the parts together, pat ourselves on the back for a job well done then tear it all down again to make it good enough to run once again. First on the list were the spars. We have them both, the rear one having come up with the big piece of the wreck and the front one recovered from over a hundred and sixty metres distant to the crash site.
Both were stripped long ago…
…then bolted to the wall in the corner against the day against they’d be prepared to go back on.
Eventually the time came to take a closer look and, as ever, the mountain of work needed to mend them reared up ahead of us the moment we confronted it. By far the biggest issue was that the sponsons had been pulled off the ends with considerable violence and where they used to fasten was a bit knackered. Worse still, on the rear spar the steel lifting brackets for craning the boat on and off trailers or into the water had won the dissimilar metal war and we had corrosion to consider too. This wasn’t so bad on the actual faces of the spar because, although the corrosion appears quite deep in places, the spar ends are half an inch thick on all four faces out at the ends so there’s more than plenty left in reserve. Still, we had to measure and assess and be confident that this was actually the case – due diligence and all that. The bigger problem was with the attachment angles that join the spars to the sponson decks.
This one got it in full measure. Torn in two then rotted to buggery…
Now anyone with any sense would retire this but mending such things has become so routine that we didn’t even think to put it in the bin. There’s always good metal in there somewhere if only you’re prepared to dig for it.
It’s a quarter-inch thick and made of the usual top-quality material and we’d also got lucky recently because one of the companies that supports us with such things had had a nasty accident with an expensive slab of tin – they’d left a quarter-inch thick sheet of 2024 Alclad outside in the rain so that was the end of any hopes of selling it to Airbus. Nowt the matter with it except you could see it had been wet so using it on an aeroplane was out of the question. We paid scrap value then nibbled the edges off to mend the attachment angles.
Alclad, by the way, has the clue in the name. The metal in question on this occasion, 2024, is a copper/aluminium alloy that’s particularly prone to corrosion because it’s two very dissimilar metals blended into one so to calm its act what they do is roll very thin layer of pure aluminium over the top because in its pure form aluminium doesn’t react much at all. Hence the name, Alclad – clad in aluminium.
The corrosion pits welded nicely once dug out with a die-grinder and the angles responded very well to our treatment. They went a little banana-shaped in the welding process but we discovered that they’d stretch very effectively back to straightness with a flat roller in our English Wheel. It should be pointed out here that mending these angles took several weeks by the time the spar-ends were stripped, the corrosion ground out of the angles then welded up, fettled and made ready to go back on.
Notice also the new bolts holding them in place. These are in addition to the pitch of very big rivets – more of those in a mo – and two bolts on each side also pick up the lifting brackets. Each of those bolts goes into a captive nut on the inside of the spar but every one was seized solid. Try as we might we couldn’t do anything with them until eventually every head was snapped off and we had no option but to go in through the ends of the spar to sort things out. Having said that, doing so wasn’t an easy call because the covers in the ends of the spars were installed before the upper skins went on. The upper face of the spar was the last piece to be riveted in and this effectively trapped the ends amongst all the converging angles but we weren’t about to take it back off so if you look carefully you’ll see where we had to sacrifice a slither of material in getting the ends free. We don’t like having to do things like that.
The view up the end of the main spar.
Here it’s all cleaned out and the captives have been de-riveted, freed of their broken bolts, which had actually seized into the spar material rather than the threads and so were easy to shift once the rivets were gone and the bolt stem driven into the interior with a parallel punch. After that they were carefully cleaned, oiled then riveted back in place. You can see some of them looking all spotless and new stuck to the right-hand wall with fresh rivets – another job that took up a few workshop sessions. The keen-eyed may also spot that everything is shiny and sticky in there due to an application of the ubiquitous Ardrox.
We saved everything that we reasonably could but we did retire some parts in the end. There’s another set of attachment angles that live on the underside of the spars and bolt through the inside faces of the sponsons. Of these we had the pair from the main spar but they weren’t very good.
It’s not that we couldn’t mend them it’s just that they’ll do a better job demonstrating the violence of the crash and the effects of 34 years of immersion while we make up new parts, an example of which can be seen behind the ruined one above. We do that sometimes.
Back in the days of the Hapless Lottery Failure and their ‘experts’ the old, ‘every piece of twisted metal is a snapshot in time’ argument never got them very far on the grounds that we had a million snapshots, most of which meant nothing and could be turned into a boat, leaving a poignant few to adequately tell the story. This is one such snapshot…
Over the ensuing weeks and months we gradually brought all four spar-ends back to this sort of standard.
The long attachment angle on the upper face is a repaired original while the one on the underside of the spar is new. Next we gave all the exposed metal a good scrub with a stainless wire brush then a coat of etch-prime.
The repaired or replaced angles got similar treatment. We’ve left the spars in their original paint but it’s all gone missing from the ends of the main spar so the etch was put there to make sure that the slapdashly-applied coat of SSS (Suitably Shabby Silver) would stay on.
One of our thorniest problems was where to find rivets big enough to put everything back together again. They’re 5/16th of an inch in diameter and that’s eight and a bit millimetres!
Can’t get those at Motor World.
To the rescue came the guys from Avdel or, as they’re now known, Stanley Mechanical Fasteners. They took on the challenge then called to say that if we could upsize all the holes to 10mm we were in business! We’d never seen rivets on this scale.
That’s a man-sized rivet if ever there was one.
Hey, hang on a moment, can we still say ‘man-sized’? I thought the humourless, do-good PC brigade must have long since banned such a potentially inflammatory turn of phrase but, no, I saw some Yorkie ‘man-sized’ chocolate buttons at the local garage the other night so man-sized those rivets remain and we soon upsized every hole in sight at the promise of them. The tool that sets them is a monster too.
As ever, quality, thoroughness and attention to detail came first so the job was carefully set up ahead of time with a fresh batch of choccie in every orifice so that when Steve from Avdel set about the rivets we weren’t taking up any more of his expert time than absolutely necessary.
These guys are professionals so everything must be checked then checked again then prepped to the n’th degree.
There’s something that just cannot be conveyed about the clamping effect of a row of big rivets. Their inexorable force is something you can only feel when you’re there and these were something else. The hiss and snap of the gun was deceptively soft but it was plain to see from the oozing choccie that we could rely on our attachment angles not falling off anytime soon.
That was one end of our main spar back together leaving only the application of a coat of SSS to complete the job. It always looks very shiny and silver when first it’s lashed on with a raggy brush but after we’ve had mucky gloves and cups of tea all over it then a layer or three of dust our humble silver paint actually weathers in very nicely and begins to look like it’s been there since Leo’s day. Even when it’s fresh and new it’s close.
Rotted attachment angles and dissimilar metal corrosion was one thing but the spars presented another obstacle with far more sinister undertones. They were shot through with broken bolts sheared off flush with the outer surface.
High-tensile bolts only really fail like that in one circumstance – when they are hit hard at very high speed.
We didn’t like to think of that too deeply.
Novie spent many hours drilling down the centres of the severed remains then carefully winding out what was left with a stud remover.
This was only a minor problem on the main spar, which remained with the craft but on the front spar it was a disaster where practically every bolt sheared and it’s a miracle that we got every last one out and saved the threads. We had only a single problem with the attachment angles too – one of them was missing completely so we made a new one from scratch and stuck it on.
The angles on the front spar are a different section to those on the main spar so we were able to use a piece of extrusion left over from the sponson build – a perfect match. So the spar itself didn’t take much mending but, whereas the main spar passed elegantly through the frame and bolted in at the inboard ends, the front spar had been lifted and relocated atop the frame.
For those unfamiliar with the story, Ken and Lew designed a boat for Donald that was built by Samlesbury Engineering that point-blank refused to work. To mend matters what they had to do was modify it drastically by hefting the front spar up ten inches then fastening it on with steel attachment angles.
The front-left one was the only example not bent in half so we popped it into the hole and hoped against hope that all we had to do was straighten the rest one by one and put them back. In actual fact there wasn’t any hope at all because they are actually very precise fabrications with the bolt holes all reamed to size. Once stretched and bent we had virtually no chance of returning them to within the fractions of an inch to which they’d been built the first time around. But we tried…
We got them pretty close too but something odd was happening. The front face of the spar was too far forward to let us load the attachment angles if we put the spar ends where they were supposed to go. There’s exactly six feet between the centres of the front and main spars, the ends of the spars must bolt precisely to structures inside the sponson so there’s no give and take there and we just couldn’t make the numbers work. We measured and measured and measured again then made up tooling to fire lasers this way and that until we could no longer deny the fact – the front spar is bent! Its arms have been tweaked backwards when it hit the water.
This caused much consternation but hope remained. If the material was springy enough it might be more held in tension by a relatively small stretch than properly bent and perhaps a good push would persuade it close enough for us to bolt it in and share the remaining error amongst the ends and the middle. We bolted a chunk of steel to the floor, positioned the spar between two convenient pillars and gave it a push.
We generated some pretty serious forces with that rig. It was like trying to draw a 10ft aluminium bow and it stored a colossal amount of energy. That’s a six-ton jack and we ran it out of ideas. Twice the anchor bolts exploded and all that energy escaped in a big violent bang. Once it let go and clattered into Barry From Grimsby and me and then, with steady development of the pushing setup, we were able to move the wall so we decided to pack it in before someone was hurt by a twanging spar or falling masonry. We’d taken about 10mm out of the bend but it wasn’t enough. We could have built another rig with steel beams that didn’t endanger the building but due to the shape of the spar, it being tapered down from the upper face towards the ends, it was beginning to twist when we pushed it and any further straightening seemed certain to solve one problem whilst creating another. It was time to stop, accept that the spar was bent and come up with a workaround for it.
The conclusion drawn was that what’s most important is the boat’s footprint. Sponsons parallel, nice and upright and neither one ahead of the other with everything aligned on the boat’s centreline. If we could set that up then attach the ends of the spars to the sponsons the middle would fall where it fell and we’d have to worry about attaching it later by whatever means.
But remember that the spar had been raised… this left a ten-inch gap between the end of the spar and the deck of the sponson that was bridged with a tower of stainless steel and ‘finest spruce’ except that for some reason I’d decided it was larch (used elsewhere on the boat) so, though they existed only as a drawing and our plans to build a pair, they’d always been known as the ‘larch towers’.
Now we don’t do a lot of stainless at our place, it’s awful stuff, so we had a walk into town where the guys at a local fab’ shop were more than willing to help by cutting and bending all the sections we needed so all we had to do was weld them together.
Stainless may not cut or drill very well but at least it’s the easiest metal in the world to weld and our towers came together beautifully.
According to the drawings they can be made one of two ways. Either fully welded or riveted together – so we did both. We fully welded them for strength then Richie put the rivets in for the sake of appearances and some extra strength and then, when checking the archive pic’s against the drawings, we found they’d done it differently again so we added a few false parts to keep the look spot on. They’re ridiculously strong.
You can also see a 3/16th thick aluminium spreader along the lower flange now too. It has these on all four flanges. But this still wasn’t enough for Ken so, in keeping with his belt and braces, over-engineering of everything approach to design, he added a pair of struts.
Each one is bespoke and built to precisely fit in its own position. There are four of them – two on each sponson – and for some reason, Ken has named them ‘drag struts’ when in actual fact they work in compression but I reckon we can forgive him that one.
Pretty much everyone took a hand in making them. Rich cut the tubes to a nicety despite the critical lengths and angles. Jordan machined the inserts for where they attach at their upper ends, Mike was the shape-police throughout ensuring that what we built was indistinguishable from the photos kindly provided from Neil Sheppard’s vast collection.
They pick up on the outermost bolt fixings in the attachment angle on the front spar and slope downwards at precisely 49 degrees to the next pair of spar frames that would have been the ‘spar neutral’ position had they ever been used.
14swg 4130 chromoly tube, stainless inserts at the top tapped to 5/16th BSF and 1/8th 4130 pads at the other end that bolt into the sponson deck. Come on… it’s way over the top. But we built it faithfully to the drawings and bolted it all together. The result… the midships stretch of the spar was a mile away.
And then we made a discovery.
You see, we knew a long time ago that the front of the frame was wrong from day-one. You can see it in the way the forward bulkheads have been cut around the frame tubes but that didn’t tell us with any sort of accuracy how far adrift the frame had actually been because we had the tolerance of the panels to factor in too and they’d been in a crash.
But the adjustments made to the spar position give it all away.
Take a close look at this pic.
To all appearances the two front steel attachment angles are inserted – they’re not but we’ll come back to that. But if you look carefully you can see that inboard of each of them is a vertical pitch of countersunk rivets. Now look at the distance between the rivets and the steel angles. The angles align with the frame tubes and bolt into them lower down so that determines the original frame tube positions with absolute certainty. Now those two pitches of rivets are equispaced from the centreline of the spar yet there’s a half-inch offset. The spar had been shoved half an inch to the left to get it back to the centreline of the boat and we didn’t do that. It was done in 1954 when the spar was fitted for the first time ever.
Here it is in more detail…
We have about 36mm or an inch and three-eighths-ish from the rivet to the attachment angle on one side.
Nearer 20mm at this side so the best inference is that the frame was half an inch out of true from the off.
Then came another gotcha because we’d missed this method of determining the mismatch back when the frame was mended and gone for 3/8th of an inch based on the panels and our difficulty believing that Samlesbury would tolerate even that size of an error so we’d not introduced quite enough wonkiness so this left us in even more trouble than before. Not only did we need to find a way to offset the attachment angles in the fore/aft plane where they simply wouldn’t fit due to the bend in the spar but we also had to offset them to the left (as you sit in the cockpit) to add just the right amount of additional wonkiness to make everything straight again – this was becoming a nightmare but then we got a little lucky. You see, this thing was hanging off and needed a fix.
It’s a big attachment angle machined from solid that fixes the front of the spar to the underlying frame tube at F-21and if you look carefully you can see that the rivets that once held it are pulled at the bottom. It was peeled off the frame tube and everything got stretched so we drilled an opposite pitch and fastened it down with a good handful of countersunk quarter-inch rivets same as the ones we used to fasten the spar frames into the sponsons.
Nothing lost but a little swarf, completely original just with some new rivets added but once the attachment was nailed back to the spar face we found an unexpected eighth of an inch gap under the spar because it turns out that the attachment actually protrudes downwards a little. We don’t know why, perhaps to allow for shims, considering that the whole frame was cockeyed, or maybe the F-21 crossmember was welded in a smoot low by ‘Shackles and Bollocks’ I didn’t invent that – apparently that was the official nickname of Accles and Pollock as told to me by an ex-Norris Bro’s employee.
Either way, we realised we could sneak something under the spar without affecting the height.
We had an idea and could have drawn it out and had it laser cut but Dave (another recent addition to our team) volunteered to speed things along by tackling the job with a cutting disc.
I did a turn on Scrapheap Challenge some years ago and made a diving helmet out of an old Calor gas bottle. It worked a treat and I ran about the bottom of the underwater stage at Pinewood all afternoon in it until we won but the H&S bods at Scrapheap told me I wasn’t allowed to use a cutting disc. We were perfectly at liberty to crawl under mountains of scrap or to tear around the place on a quad bike but a cutting disc… no chance.
I explained that I used one every day of my life and argued the case until they let me loose with one. H&S wombles possessed of common sense… respect!
Dave, on the other hand, had no such difficulty and soon had the required shape chopped out. We’d first mocked it up with a piece of ally so he knew what he was making. It turned out as though laser cut at the first attempt.
Introducing – ‘The Table’ an eighth-thick sheet of specially milled 4130 chromoly, which is more or less what the attachment angles are made of. Can you see where we’re going with this idea?
The best fix, we decided, would be if we could put suitable offsets in the attachment angles but that was a big ask. We’d have a hell of a job trying to bend them to shape then have everything line up again but what if we could cut each one in half and weld its lower half to the table such that it bolted into the frame and its upper half such that it bolted to the spar?
The foremost angle is a new one to replace the one of the six that’s still in the lake and, whilst they’re only tacked to the table at this stage, it’s plain to see that this is going to work. There’s a small weight penalty in the additional material under the spar but we’re allowed something back for the volume of expanding foam we’re not putting in the sponsons so we’re still ahead.
The top was easy to work on but welding the angles into the underside had to be done completely by feel and out of sight. That was challenging to say the least but we nailed it with a spot of blind MIG welding. Notice the blue glow visible through the gaps at the back of the spar…
Of course, all the carefully positioned angles moved around when the proper welds began to go in leaving lots of final fettling but by now we had the spars and sponsons properly positioned and a means of bolting it all together. Pretty cool, eh.
By far and away the most FAQ is the ‘when’ question and by far the best answer is, how the hell should we know? We could never have attempted to guess how long we’d be beset by front spar problems yet behind the scenes there’s still the occasional would-be project manager who reckons they could do things differently to come up with all the answers and I still invite any one of them to come and show us how.
Take for example the installation of the captive nuts in the sponson decks, because once the final position of everything was determined we then had to provide the means to bolt it all together.
Remember the struts that everyone helped to build? Well John wasn’t to be left out and to him fell the task of fitting the captive nuts to hold the lower ends of them to the sponson decks.
Sometimes it’s easy. You just drill the fixing hole where it’s supposed to go – and don’t forget, these are the actual fixings that will be holding the sponsons to the ends of the spars when the Orph’ throttles up – pop a captive on the back and rivet it in, simple. Well, as simple as positioning the captive with a bolt, drilling its two fixing holes back through the spar frame then removing the captive again to deburr and countersink before applying choccie then setting a couple of 1/8th rivets upside down in a void can be.
But this is the aft face of the last spar frame and it can be easily accessed, the forward face is a different animal. There are three alternate positions for the spars. Spar-neutral in the centre with spar-aft ahead and spar-forward behind it at nine-inch centres. Only the spar-forward position was ever used so, thankfully, we don’t have to put a full set of captives at each position but we do have to fully equip the spar-forward position and the problem is that it has the neutral position immediately ahead of it and that almost totally closes off access to where we need to work. We ended up having to build little widgets like this in order to load several captives at once and avoid the need to get on the back with a block to set the rivets.
It has to sneak into that tiny triangular gap (yellow arrow) and the hole partially covered by the middle captive (blue arrow) is to fit over the tail of the rivet you can see in the packing strip in the spar frame just above the leftmost captive (red arrow). And if you look carefully at the packing strip in question you can also see the pencil marks where the rivets will be set to hold the widget in place.
See what I mean about how tricky it all became?
The leftmost hole is a bit of a disaster because it fell half on a rivet that we had to remove but the captive is perfectly aligned beneath it. All that remained was to choccie and rivet then cut off the tag we used to load and unload it – it took half a day to get it spot on and installed and that’s where the time goes. And this only covered the three holes you can see – there’s another three to the right and they really cannot be accessed from beneath. We reckon it’s actually impossible to build the exact sponsons that Norris Bro’s designed and that whichever way you try to tackle them there absolutely must be compromises. One of ours is that the other three fixings in that attachment angle employ Helicoils rather than captives.
Helicoils… way back when, designers and engineers were faced with the conundrum that magnesium and aluminium alloys are plenty lightweight enough to make aero-engines but they’re hopeless materials to put threads into so someone had to come up with a fix.
The problem is that if you drill and tap a hole in such a material then tighten a bolt into it the metal flexes until all the load ends up on the top couple of threads, which then strip out and that becomes your limiting factor. So what some genius came up with was to drill and tap the hole then insert what amounts to a stainless spring that mimics the thread you wanted in the first place and into which you can screw your bolt. The result being that the load is spread evenly throughout the entire depth of the threads due to the spring being able to move about a little and the limit of how tight you can then get your bolt without stripping the threads shoots through the roof in a good sort of way. They really are an incredible fixing and yet psychologically they just don’t seem as clever as a good, old-fashioned nut.
We’ve even put this to the test by Helicoiling a scrap piece of sponson side skin then trying to wreck it with a 2BA bolt – this to solve the totally impossible question of installing captives in all the places Ken said they should go. It wrecked the bolt first despite the fact that it only had 2.5mm of threads to pull out of a sheet of ally. They really are bulletproof things yet we still don’t like having to use them in place of captives for some inexplicable reason…
This has just as many threads as the captives we’re using, it’s perfectly executed in a piece of high-duty alloy straight from the aerospace shop and we’ve dogged a bolt into it as hard as we can pull on the spanner with no ill effects but it’s still a Helicoil – we really must get over ourselves on this and accept what our senses tell us. Nor is it Cadmium plated so there’s another advantage over the old hardware we often have to employ. Cad plate – now there’s something to really get the H&S wombles soiling their underwear. It’s like asbestos or radium or a step ladder without a sticker at the top to tell you when to stop climbing – it’ll kill you as soon as look at you. Our policy with cad plated anything is to simply not to eat too many of them.
So now we have all the fixings into the sponson to bolt them on properly – with bolts. Not clamps and pins and a bolt here and there but real bolts in all the right places. It doesn’t sound like much but it was a big job to get all these fasteners into place and with that done we were able to fit the sponson lids, find and drill all the bolt holes in those then spanner the whole structure together.
You’d have to look hard to tell it from the original and as the museum people who watch the Barra’ said – it must be true, it’s in colour.
Make it monochrome and you could be back in 1967.
A couple of Mike’s excellent pic’s there…
But looking OK is only part of the solution because having been built wonky form birth then shimmed and spaced and slotted to get the footprint and geometry near as possible it was then crashed and smacked into pieces, collected up and reassembled and now has to navigate in a straight line once more. Trouble is, there’s just no way to accurately measure how close we are with tape measures and string (or so we thought) so we had to go a little more hi-tech.
There’s a local company called Precision Geomatics that specialises in measuring things and we mean seriously measuring things… we got a small taste of their capabilities when checking how accurate the main spar was to the centreline. Along came a man with a laser and we positioned prisms on the ends of the spar and at the centre at the back then let the laser measure all the distances and angles. That gave us data on the main spar relative to the centreline and that’s all but it was jolly impressive. It did not, however, tell us anything about the sponsons or the front spar or anything else relating to the part we’ve so carefully mended. That was until Barry turned up with an absolutely gobsmacking laser to do a whole different measuring job.
We now have three Barrys. There’s Barry Hares, a genuine living legend but for those unfamiliar with his work just Google ‘Barry Hares Eagle Engine’ but make sure you’re sitting down with something nearby to mop up the drool. Then there’s Barry From Grimsby, or BFG for short. BFG is a good hand and such a great bloke to get along with that he became one of the crew with immediate effect, and now there’s ‘Laser Barry’.
Job-one was to attach spheres all over the ceiling… yes, you read that correctly. They were like Christmas baubles with magnetic bases and up a ladder I had to go and stick them all over the RSJs. They’re references for that box on a stick that Barry is twiddling with.
Right – here we go. That box on a stick takes about ten minutes to look all the way around itself with a laser and in so doing it measures and logs, each with its own angle and distance and reflectivity, forty-four million separate points! Then it takes about eighty photographs onto which the laser data can be overlaid and then it beeps to ask for more. The spheres on the ceiling are there so it can find them all then automatically reference together multiple scans shot from different positions around the room until it has produced a 3D CAD model to an accuracy of about 0.1mm of not only the boat but the inside of the building and everything else right down to the sweepings on the floor and the teacups. It’s just ridiculous!
Here’s a cleaned up screen grab.
But this is not just an image…
It’s the model that we now use to check our work in rigging the structure. We couldn’t wait to find out how we’d done in setting up the spars relative to one another and the best way seemed to be to check the diagonals. Barry clicked away with the tools in his software and measured from a point on the outer corner of the front spar to another on the end of the main spar on the other side of the boat – 3.855metres. Next he positioned the cursor on the opposite ends of the spars to check the diagonal the other way; 3.855metres again. We got the spars correct to three decimal places with only some tape measures, patience worn thin and sheer perseverance.
Happy with that…
Next we have to put the lids on the sponsons, make the rest of their upper fairings and all the bits and bobs to cover in the spars with tinware and that’ll be the bodywork done. Engine and systems after that and most of the work is done there too, all we have to do is make it all fit in the hull with its various hoses, wires and linkages then pull it out again so the boat can go back on the rollover jig, floors and side skins after that and we’re there. The canopy is the only big unknown that we have now but we can do it.