March 2012
The car park was full of cops when I arrived. I threw my backpack over my shoulder, grabbed my laptop and slammed the boot. The hotel reception was no different, it buzzed with excitement and police radios. Clearly something big was occurring yet there was nothing to see. One of the staff had written down a car number, an officer took it and ran past guests vying to tell of the stranger they’d glimpsed fleeing the scene. But no bloodied corpses nor bullet holes stitching the modern glass frontage were evident and yet there was certainly hell to pay over something.
“What’s happening here?” I asked, having confirmed my booking. The girl tried a nonplussed look in keeping with company policy. For professional purposes the riot squad in the hallway didn’t exist.
“You have wall to wall fitted cops…” I explained, stepping out of her line of sight in case she hadn’t noticed them.
“Oh, those.”
I waited patiently, not quite weighing over the credit card.
“There was a man,” she began hesitantly. “Outside the swimming pool looking through the glass with his phone, taking pictures, and a kiddies swimming lesson was going on, and he ran away.”
It all sounded rather sinister and now I could see why the cops were charging about despite there being no blood to slip in. It was only later in the evening that I discovered I’d actually witnessed the final straw in what was probably the worst day of some poor sod’s life.
You see, as the drama was buzzing around me, I’d heard a girl from the leisure club complaining that such events always happened on her shift and remember wondering at the time whether the bloke with the camera actually had a thing for cute blondes. Then, later on, she appeared behind the bar and as I was in need of a fresh pint I captured her and asked whether the child-raping paedophile had been caught and emasculated with a rusty hacksaw blade yet.
“It wasn’t how it seemed,” she said.
Well it never is, is it…
What really happened, it transpired, was that the poor bugger had reason to suppose that his girlfriend was sneaking about the hotel with another man. Now anyone with any sense would assume the missus and her new hero would enjoy a quick rumble in the bedroom followed by a post-coital sup of pinot in the bar so what you’d do is stick a baseball cap on your head, order a beer then sit by the door but not in full view so as to retain the element of surprise when they walked in – not peer through the swimming pool windows twiddling with your iPhone.
Anyway, that seems to be what he did so next thing is the cops have nabbed him and, for a moment at least, he’s right up there with Garry Glitter until, having suffered the indignity of having his phone thoroughly inspected inside and out, he was sent on his way with no more than a stern ticking off.
Now just how miserable would you feel later on picking at your takeaway with a fork knowing just what a crap day you’d had – especially if the girlfriend rocked up with an equally innocent explanation for why she’d been off the radar all afternoon? I had to howl with laughter yet ache with sorrow for the hapless individual.
It reminded me of the desperately unfortunate museologist who told me how K7’s accident was a snapshot in time witnessed by countless thousands and rebuilding it would destroy history – and the next day Cutty Sark burned to a crisp. Or that terminally stupid HLF officer who told me I couldn’t sack him unilaterally because I had to go consult all the other people who wanted to sack him too. I mean, who in their right mind would want to be sacked twice? It seems he did.
But that was then and this is now. So far as I know they’ve all moved into obscurity or been locked in secure units and I think we wrung as much beneficial change out of them as we were going to get some time ago so that’s that. The museologists seem to like us a little better these days and some of them are actually pretty cool but the HL-effers, pah!
And then a peculiar thing happened – I was invited to attend a HLF bash and hand out certificates to students who’d completed a course of some sort.
Who, me? The Yasser Arafat of the museum world…
In fact these days my chickens are growing fat from pecking over the patch in the garden where the hatchets are buried.
So with all this goodwill settling like snow and K7 being riveted back together at a rate of knots previously unseen, morale is at an all time high. We said a long time ago that one day everyone would be on the rivets and so it’s come to pass. What’s truly inspirational about our crew is that when it’s time to learn a new skill everyone simply picks up a new tool and cracks on to the usual standard without fuss or drama.
Something that happens often during all this assembly work is that you find yourself wrong way up in a confined space staring at a rivet wondering just how they managed to set it back in the fifties. It’s like crossing paths with the past and, having been working on the systems for a while now, there’s a question someone absolutely must have asked when faced with the new Orpheus.
“How are we going to start the damn thing?”
Those concerned with re-engining Bluebird for the 66 attempt had to contend with spannering a new lump into the space formerly occupied by the venerable Beryl but getting that going wasn’t a problem because it came with an electric starter and rowing alongside with a few batteries in the bilges and a set of jump leads was easy. But the Orph’ came with an air turbine starter that needed a great blast of air from a ground starting trolley and sticking one of those in a rowing boat was a different matter altogether. What to do?
As it happened there was one Orph’ powered machine with a self-contained air start system around at the same time, the Hunting 126 experimental aircraft. It used thrust ducted from the engine to blow high speed gas over the tops of the control surfaces giving it an extremely short takeoff run and exceptional low speed flight characteristics but this draining of thrust gave it poor performance when it was supposed to be going fast so it was not a great success generally to the extent that a second planned aircraft was never built so guess what… that left a spare set of start equipment on the shelf.
The kit was made by Lucas Rotax and in March 1966 the spare set was ‘borrowed’ by a certain Mr Campbell and never given back. Thirty-four years later we pulled the top off his dripping boat to get a look at what was left.
Not very good, is it. All that time at the bottom of the lake had completely knackered it.
(Pic by kind permission, W. Vanryn)
The entire start system hangs from the frame carrying those two spherical air flasks. It’s an elegant setup with so few moving parts you can count them on one hand, total self-containment and light enough that you can pick it up with the other, but there’s also a shocking amount of energy stored in those bottles that must be released in a controlled sort of way if you’re to avoid death or serious injury.
Fair enough, we were told that the fuel system might cause a small explosion, but at least we’d have a chance of running away, jumping in the lake or otherwise avoiding the imminent fireball if that lot went up but if a HP bottle exploded in your face it would be lights out without warning so we had to consider very carefully just what to do with such a badly corroded (to all appearances at least) bomb. Conserve or conserveer?
First thing’s first – take it apart to see what we were working with.
All the essentials are attached to the right-hand bottle by simply screwing them one onto the other like some weird, kid’s construction set but mending that lot was secondary to having somewhere to store the air in the first place so the bottles came under scrutiny first.
Outwardly they were in excellent condition and internal inspection with a boroscope revealed that the right-hand one was good inside too with no water ingress and only a light dusting of surface rust but the outside had pitted here and there. We sought the advice of a specialist who told us that carrying out hot work on the bottle was permissible so long as we used the correct TIG rods. The ones selected are for making welds on high pressure gas pipes so we had the bottle blasted, ground out the pits and filled them.
With that done we polished the surface.
And that was that bottle good to go – to the untrained eye at least – but that’s not the issue when dealing with HP air. Honestly, it’s lethal stuff so we took the repaired bottle to the local testing facility and had it blown to 3200psi, it’s old working pressure, not with air but with water.
Water is incompressible for our purposes so if the bottle fails you only get mildly splashed not blasted with shrapnel but the gauge stayed there quite happily for half the afternoon without losing any pressure or weeping a drop. We then imposed a new, max working pressure of 2000psi, which is more than enough for our purposes, then we went for a look at the other bottle.
It wasn’t good. The right-hand bottle carried the start equipment and the various valves did an excellent job of keeping it dry inside but the left was only for storage and the corroded fittings had let the lake in. Only to a depth of an inch or so but it was enough. The pitting on the outside was much deeper too so we did the only sensible thing and cut the bottle in half. It sounds drastic but it was made in two halves to begin with then welded together so all we did was take the weld off to reduce it to its component parts.
The damage didn’t cut deeply into the metal but it gave the inside surface a pitted finish and cracks like to grow from any sort of irregular surface. We ground the metal back a millimetre or so in one-inch squares then built it up again and polished the interior. It took an absolute age!
Every last blemish was ground out, repaired then polished inside and out and that is bloody hard steel!
Then the bottle was given a 45 degree weld-prep around both halves, tacked together and purged with pure argon before being welded in three, non-stop passes to put the root of the weld in, then to fill the weld-prep level with the outside of the bottle and finally to cap over the top for maximum strength.
That amounted to twelve feet of continuous weld and once complete the second bottle easily sailed through its hydraulic test and is arguably now the better of the two. So now we had reliable air storage – so far so good – next we needed something to hang it all from. At least that was easy because the frame that mounts the start system is a straightforward lump of fabricated steel with no moving parts or the possibility of exploding, melting, running away with itself or any of the other undesirable things that many of the parts dealt with recently may like to do. It wasn’t in the first flush off youth, however.
Cockney Chris soon had it fettled, though, with some patches and welding and grinding while the rest of the crew did some equally clever metal grafting with the spiders that hold the bottles to the frame. Being thin steel they didn’t come out of the whole crash, sink, fizz for thirty-odd years, thing very well.
But they fixed up nicely and we even saved the original rubber that protected the steel clamps from the steel bottle.
Believe it or not, the above is mostly original. As is this little lot.
That’s the bulk of the start system back together and it’s all the little awkward bits from here. The devil is in the detail, as they say, especially when you want the detail to safely handle HP air.
First of the downstream widgets is an air valve that basically opens the right-hand bottle to the outside world at the push of a button while the two bottles are equalised by a hose that runs under the engine inlet trunk.
The main valve has what’s known as a balanced piston inside. The piston has tank pressure either side of a seal midway along its length so there’s no tendency for the air pressure to push it one way or the other, then there’s a spring to hold it closed against a seat so no air can escape to the outside. But suddenly release the pressure from the back half of the piston and now you have tank pressure at the front versus only the spring at the back so the spring loses and the piston flies backwards allowing the air a bid for freedom. The nose of the piston is shaped such that aerodynamic forces keep it held firmly out of the way once the compressed air starts to move.
Restore tank pressure behind the piston and now the piston is balanced again leaving the spring in charge so the valve slams shut. As with the fuel pump, a simple concept that now only has to be made to work safely and reliably. Uh-huh… easy, is this conserveering.
The valve was very sorry for itself with extensive corrosion due to it being in the proximity of so many different metals and, indeed, being made of so many different metals itself. There was some hope, however because the upstream end of the piston was immaculate as it had kept the water out of the bottle all that time so maybe the rest of it had survived.
Unfortunately it took a hydraulic press to get it out and that says it all – shame.
Once stripped, the valve body was thoroughly blasted to see exactly what was left – not a lot, as it happened.
But notice that some of it has already been repaired because it welded nicely. Sometimes it was necessary to chase the corrosion down the grain of the metal. It shows in the weld pool as a black spot so what you do is stop and dig it out with a die-grinder then arc-up again until the spot reappears, or not, and you continue this process until nothing but a glistening pool of liquid aluminium appears at the bottom – then you fill it up again.
First it was given a lot of reconstructive surgery followed by as many hours of cosmetic work.
From there it went to the workshops of Algernon Precision Engineering here on Tyneside to have its guts made to work again. The piston was dead and the bore was corroded too so it was taken 0.5mm oversize and a new piston machined to suit.
Old piston top, new one beneath with both laid on the drawing so you can see where it goes. That got the bulk of the main valve back into operation because the spring was immaculate and was reused – what next?
Remember how the balanced piston thing worked, with air released from behind the o-ring seal that you can see halfway along the piston? That’s done by what was referred to back in the day as a ‘piggyback valve’.
Here it is and note the part number. M4901 EXP.1
This, I am told, refers to an experimental part so it was certainly worth trying to bring it back to life in the interests of originality. It works by means of a solenoid, beneath that black cap gripped by fingertips at the left, that pushes a stainless steel shuttle a tiny distance measured in thousandths of an inch to unseat one valve and firmly seat another. The shuttle has sealing faces along its length and when at rest it allows tank pressure to pass straight through to balance the pressure either side of the main piston. But push the start button and the shuttle closes off the space forward of the piston and vents the aft space to atmosphere. It’s a really close-tolerance part that we were told we’d never get going again.
Its internals seemed not too bad but the main casting had corrosion on the o-ring seats so we shelved it for the time being and went in search of a replacement on the basis that we had problems to solve on the main valve that might mask problems on the piggyback valve and vice-versa were we to try mending them simultaneously.
We knew that both evolved into the rapid start system on the V-Bomber force so a scratch around inside a Vulcan solved the problem…
There you go – a genuine M4901. A little grubby maybe but in full working order so we could use it to test the main valve when the time came but we had an outstanding issue with the main valve in that it contained a second, smaller valve designed to lift and at least warn anyone nearby to dive for cover should the pressure in the bottles go critical. To this day we’ve not fathomed out exactly why it’s designed as it is so all we could do was try to put it back as it was.
It’s a stack of tiny parts including needle valves and seats and springs and o-rings and something made of nylon that we melted whilst trying to get the thing apart and then had no hope of identifying – dammit!
Now around this time I received another of those mails from somewhere deep in the heart of a massive corporation from a man at his desk who wanted to help, one of those mails that suddenly changes the whole landscape. You see, ’til now, we’d had no real information about the parts of our system. Google, Lucas-Rotax and you’ll see what I mean, it just evaporated without a trace, but like the rest of British engineering it’s not gone far because it’d been absorbed by the mighty Goodrich Corporation and become part of Goodrich Power Systems.
Here, I was soon to discover, everything we could ever wish for was stashed away in their archives. Don’t you just love aerospace…
The problem was the lawyers. In principle the company was prepared to help but it took a while to get a disclaimer written up by the legal-eagles to the effect that if we exploded something they’d supplied drawings for we were firmly on our own. Being on our own is nothing new and being a diver I had a very healthy respect for the dangers of HP air so a deal was done and we presently acquired some archive info. An especially arduous task for the lady in the print room who uncomplainingly pulled dusty old drawings every time I asked then scanned and entered them into the modern system so they could be e-mailed. I sent her a nice bouquet of flowers to say thanks though I suspect a shiny, new car would possibly have been more apt. But could we work out what the nylon whatnot was that had melted over everything? Not a chance.
Around this time we also started swapping notes with Bill Vanryn.
Bill is a splendid gentleman of ninety-something who can quote part numbers, material spec’s, test procedures – you name it – and who also has a wealth of notes and data going back forty-odd years. His memory is incredible. That pic’ was taken in 2001, by the way. He’s also the engineer who was sent from Lucas-Rotax in 1966 to install and commission the air start system on K7.
Unfortunately, though, Bill couldn’t remember what had had nylon in it right at the bottom of the relief valve either. Barry and I had a crack at it next by laying out the parts and comparing them to the GA (general arrangement) drawing we had of the valve but its method of operation remained a mystery so we couldn’t second guess what might be at the bottom though Barry got the closest, as you might expect.
So we went back to Goodrich and slowly worked through drawing after drawing getting further and further into the sub-assemblies thanks to the dedication of the lady in the print room until weeks later when, at last, an innocuous little drawing turned up entitled ‘seat and cap assembly’. Eureka! We’d found it. It was a tiny nylon seat for a needle valve set in a stainless cup with an o-ring but without it we couldn’t keep the air in and without knowing what it was supposed to look like we couldn’t make a new one. I immediately mailed the info to Barry and Bill. Barry called to say he’d make one straight away. Bill suggested Barry didn’t bother because he had a couple in his tool box from 1966 that he’d pop in the post. Would you believe it!
And with that we completed the main valve or at least we had all of it in the same place but it wasn’t tested. We’d leave that until we’d connected up the other bottle as this meant a similar process and another, identical pressure relief valve. We stripped and cleaned the fitting from the other bottle.
You can see how the corrosion has struck along the grain of the casting and the sad fact is that the metal simply isn’t as good as what we’d expect today. It’s full of inclusions and impurities and the casting process just wasn’t up to scratch either so at least when we replace what’s been lost we know it’s quality material that’s taking its place. Once rebuilt and machined all it needed was the usual cosmetic fettling to make it look the part.
In actual fact this part failed its testing when a tiny leak appeared on its surface at 1500psi. Once the pressure was drained down and the fitting removed, fluorescent dye was applied to the outside followed by a black light shone into the interior to reveal where the dye had struck through a pore in the body of the casting. It was soon ground out and closed once and for all. We like to be thorough on this job…
Almost there, a little final finishing with needle files wouldn’t go amiss but mechanically it’s great. Notice the T-shaped handle sticking out to the left. That’s attached to the pressure relief valve. The valve will either lift if the pressure in the bottles rises too high or you can pull on the handle and let some air out to be sure everything is working.
So now we have safe air storage and a reliable means of letting it off the leash but how to get air into it in suitable quantities and at the right pressure?
The system is filled through a charging valve that came out of the lake as crusty as everything else.
Here’s the valve during the stripdown in December 2005 with the dust cap still in place and below, back to its component parts for cleaning.
Below is the complete charging system. From the charging valve compressed air travels up a small-bore brass pipe to that silver cylinder mounted to the frame alongside the bottle. That’s a sintered-metal particle filter into the top of which is screwed a small, non-return valve so once the bottles are charged you can remove the charging hose and send your boat away down the lake.
The new fitting for charging was made from scratch by Barry.
From the non-return valve the air is then taken over the top of the bottle through a (new) rubber hose to a T-piece that screws into the main air valve. All the brass pipes are original with new fittings.
Here we are – the complete system back together, (airtight to only 500psi at this stage) but it works.
It’s not really complete… in fact what is arguably the most important piece is still missing because there’s no use in blowing tank pressure into the start turbine – you’d either over-speed it or damage it or both so the output pressure must be regulated and this is the beastie that did the job.
The PRV (pressure reducing valve) is the shiny silver bit at the bottom, the upper item is a brass block used to connect the PRV to a flexi hose leading to the engine. The lump sticking out the left of the brass block is an over-pressure relief device called a bursting disc – basically a thin, domed disc made of nickel only four thousandths of an inch thick designed to burst if things get out of hand and release the air safely.
But getting back to the PRV, which was mint inside and came apart easily as it’s made of stainless and bronze…
The gubbins on the right fits inside that on the left. Top is a piston that runs in a ported sleeve and the output pressure is dependent on how high the piston rides within the sleeve and therefore how many ports it uncovers. Once again very simple in principle but then we hit another problem because the piston is controlled by a slave valve on the top that turned out to be completely and utterly FUBAR.
It doesn’t look too bad from here but unfortunately its tiny interior spaces had filled with corrosion product and jammed everything solidly with no hope of stripping it down. The big culprit was a hydroformed copper bellows with a convoluted outer surface that ended up thoroughly encapsulated in expanding oxides trapping behind it an arrangement of tiny parts that normally shuttle back and forth minuscule distances opening and closing valves to control the larger piston below. After all kinds of efforts we concluded that the only way to get in there was with a die-grinder.
That did the trick and you see it here with the corrosion product cleaned away; just imagine trying to draw that copper bellows out with what amounted to concrete cast around it. So from there it was a fairly simple job for our mates at Algernon Precision to reverse-engineer the casing and make us a new one.
Richie here is a bit of a whiz on his milling machine as you can see.
Once complete the whole system was given a thorough going over by Barry to sleeve an old thread here and there where doubt remained about the stresses involved and have a crack at getting the original Piggyback valve working. And get it working he did but it’s still throwing the occasional problem our way so it remains a work in progress – we’ll get it.
Not so the little contents gauge that allowed Donald and his team to get a look at how much air was aboard as they shivered and battled with a recalcitrant machine though the winter of 66. It’s almost entirely made of brass so Barry had no problems refurbishing it and making a new pointer. Good as new.
Bit by bit we assembled the refurbished parts then mounted the system to the engine in its correct relative position. It looks quite impressive and, if I may say so, very 1966.
If you look to the right you can see our HP compressor too. Considering the amount of careful testing necessary to bring this system back to safe working condition we could see no practical way of carrying enough air into the building already compressed in cylinders so we acquired a compressor to charge the start bottles on demand with breathing quality air. We also added a brand new precision regulator so there’s no chance of the pressure getting out of hand, and a tacho indicator to see how fast the engine is spinning – but one thing at a time.
First we had to calibrate the PRV so we had enough air to spin the start turbine without over-speeding so we machined up a test nozzle to the original Lucas-Rotax specifications and stuck it firmly on the end of six feet of one-inch bore hydraulic pipe as per the instructions.
The idea being that it accurately simulates the back-pressure exerted by the start turbine so if you get accurate data with the nozzle fitted your starter is going to work properly too.
Now then… the spec’ also calls for a 0-300psi pressure gauge but we reckoned we could do better than that and soon a bloke called Peter arrived with a high speed pressure transducer and a laptop.
It all looked very Formula-1 and we ran dozens of dead cranking cycles on the engine generating pretty graphs each time until it became apparent that we had two problems.
Fisrt – the tacho indicator wasn’t reading correctly, mainly because of the explosive nature of the engine start cycle. The gauge contains a small, three-phase motor that drags an induction cup around to move the needle and this motor is powered by a similarly small generator driven by the engine gearbox. The two are directly connected by a wire, the idea being that your RPM indication is completely independent of any other wiring in your plane. The problem is that for the indicator to properly represent engine RPM both motor and generator must be in phase with one another and that’s simple enough when you’re cruising about the sky gently spooling your engine up and down but with the air-start system it spools up so violently that it hits start speed in about four seconds then spools down again by which time the indicator hasn’t even begun to catch up. It’d be like Linford Christie racing Mother Theresa to the corner shop and back.
We got around this by mounting a laser tacho on a tripod and aiming it up the back end at a piece of reflective tape stuck to one of the turbine blades. It only gave an accurate reading if the laser was pointed at the strip when the go-button was pressed otherwise it counted every blade until the strip came around and gave a reading of a zillion revs per minute but once we’d sussed it, it gave very accurate, real-time readings. There was also a compatibility issue with this combination of engine and indicator that we had to fix but that’s another story.
The second major problem was that no matter what we tried we couldn’t get the system to deliver the required 250psi at the test nozzle. It was all out of ideas at only 150psi and, worse still, the pressure decayed over time so by the time the engine was going fast, the air was going slow – we’re talking in fractions of a second here, by the way. We fiddled with everything we could think of but nothing seemed to help so, assuming we’d done something wrong in the reverse-engineering of the PRV, we left the problem on the shelf for later and set about the difficulties of getting the system to actually spin the engine.
And herein lay yet another problem because the Orph’101 uses a different start turbine to the 701 where air is delivered 90 degrees away from where all our hardware wanted to send it. Looking at the front of the engine, the 701 starter takes in air at the 9.00 o’clock position whereas it’s only 6.00 o’clock for the 101 so Cockney Chris and I spent an entire Saturday making the most impossible piece of ductwork to not only deliver the air quarter of a circle away but also to fit inside the original inlet bullet, which is so snug you’ll find more spare space inside Wayne Sleep’s underwear.
Even with all our care and attention we still had problems here too. You see, apart from our new piece of ductwork, the plumbing is integral to the inlet bullet and O-rings kept blowing out where we couldn’t see them and we couldn’t work out why so we made up a few bits and bobs (namely that gubbins at the right-hand end of the pipe that turns everything through 45º) to allow us to operate the starter in an unclothed state. By the way, the above pic’ was taken with the engine upside down.
Many hours were spent chasing and eradicating air leaks until at last we could leave the system charged to 1500psi for days on end without the pressure dropping. Pretty impressive, eh.
But would it work?
Turn your speakers up LOUD
Oh it works all right! And that’s only with 150psi flowing through its veins and that’s something that continued to puzzle us. Why wouldn’t it crank up to the 250psi every piece of documentation we could find, including the Rolls-Royce manual for the Orph’ and bundles of Lucas-Rotax stuff, said we should be seeing?
The answer came from an unexpected angle. Remember that our valves and widgets eventually evolved into the V-bomber rapid start system? Well that was one lot of data we obtained relatively easily having ‘borrowed’ a few Vulcan bits and amongst the various drawings and notes was reference to an ‘ITP’ or ‘Inspection and Test Procedure’. It was written down as a document number with ITP as the prefix followed by the part number of the valve in question so I took a gamble and requested a document I wasn’t even sure existed with ITP at the start followed by the part number of our experimental valve.
They found it, only four pages long, but it was there and partway through it mentions a ‘metering orifice’. Now I’d long suspected that the PRV piston wasn’t floating high enough in its cylinder so not enough ports were being uncovered to allow the required airflow but I had no idea why this should be, but with those two words the answer landed like a fat lass falling off her ice skates.
The drawing was swiftly dug out.
Essentially what happens is that some of the air in that little slave valve with the copper bellows is bled to atmosphere through the metering orifice so the pressure it allows through the main valve is moved up a step in proportion to orifice size. Simple – and this also explains why the pressure in the system was decaying, because it was rapidly equalising across the piston in the slave valve and stopping it from working. With a constant, controlled leak on one side of the piston it can never equalise. Problem solved. Now all we had to do was drill a small hole in a blanking plug we’d assumed was solid, but wasn’t, and have another go. Unfortunately, though, by the time this discovery was made we’d flopped the engine the wrong way up to install the fuel system and all the air hoses were disconnected so we’re going to have to wait awhile for the next opportunity to blow ourselves to kingdom come… I’ll wager now that the fancy duct will not make it. It’ll explode in a shower of shrapnel or blow itself across the workshop in a horribly deformed mess but one thing seems fairly certain, it’ll not take an extra 100psi. Just as well then that Checkie has remoted the start switch (though I thought 125 metres was excessive even for what we’re working with) and we’ll be able to blow things up from the relative safety of the next room. That duct will most likely emerge rebuilt in stainless but we’ll see.
Then, just like the rest of this job, nothing about the fuel system gave in easily. The difficulty this time is that the 701 kit, as recovered from the lake and so meticulously rebuilt by Aero Engine Controls, was never meant to be bolted to a 101 Orph’ so the bloody thing doesn’t fit! It’s not even close.
Take the filter bowl, for example.
This is Donald’s original and it provides the foundation for the whole installation by bolting solidly to the underside of the compressor casing thereby providing a mounting for the other modules – except it won’t bolt to a 101.
The pump, on the other hand, spanners into place without fuss and was the first and last part to give in so easily.
To make the filter fit we had to lower the little turret on the casing as far as the Sharpie line then drill the hole a little deeper and fit a new helicoil so we could fasten down an adaptor plate.
Warning!
Those of an aerospace disposition should stop reading now.
There’s no arguing where the filter and pump go with relation to one another because the pipes that connect the two are solid, sealed with o-rings and must be properly aligned. The adaptor plate, seen below in its earliest guise, solved the problems of mounting the filter.
From there we were able to mount the CCU.
And here too, because this is a non-standard installation, we added some extra meat in the form of a stainless bracket to support the outer end of the unit using a redundant fixing on the CCU itself.
That’ll stop it falling off. From here all we had to do was mount up the AFRC, PRC and all those other acronyms so a smart, aluminium bracket was grown from a few scraps of 3mm H22…
…and the rest of the goodies were hung from the engine.
All that remains is to connect up all the hoses to make it work – there’s plenty of those – and in the meantime our chief in charge of electrickery, Checkie Rob, has made a panel for test running our various assorted engines. We’re ever mindful that we’re under the watchful eye of the aerospace community and we’re very respectful of their ways so we do everything by the book.
Another thing Checkie’s organised is a tri-axial accelerometer to measure vibration on the fuel system in three planes because it’s not mounted as intended and rather than assume it won’t drop into the bilges it would be more professional to have a bunch of data to prove the point.
Elsewhere on the machine we’ve been tin-bashing like crazy. The air intake is as good an example as any and I’m pleased to report that it’s finally nearing completion.
Note the shiny, thickened inlet lips. They were an absolute nightmare to get right. Making new ones would have taken all of an afternoon but instead we split the originals into pieces and carefully reworked the material back from whence it came – they’re a really nice job now. In actual fact, thickening the lips seems not to have been the aim at all. What they were really trying to do, so far as we can tell, was prevent the inner skin of the duct separating from the original lip by riveting a capping over the top.
Those lips are a perfect example of why we can never answer the ‘when will it be finished’ question. How were we to know they’d occupy us for four weeks? I say it again – do you want it now or do you want it right?
The plates pinned into the throats are a work in progress too. After much study of the blanks used to keep stuff out of the engine we reached the conclusion that they were actually made of two slabs of reasonably heavy tin with a foam filling squeezed out a couple of inches all the way around. This foam was clad with some sort of canvas, the plates fitted with a pair of cheap sash handles and the whole lot slapped with more yellow paint than Gauguin could get through in an afternoon. The set up also included the means to bolt them in securely for long periods of storage or transport or whatever so Mike has built those bits too. Unfortunately, though, once the new lips were fitted, historical pic’s show that Donald’s original blanks didn’t fit anymore so ours have been tweaked accordingly in case little oiks visiting the museum find those openings just too tempting when disposing of their sweetie wrappers. The new ones will be snug as can be and firmly fastened too.
As you might imagine, weight saving is everything once you get this far forward but strength is vital too and it seems the Norris Bro’s. sailed just a little too close to the wind with their original design. We’ve made a few changes based on the reasons for the earlier failures, all of which can be seen in the fixes applied to the original ductwork, so with a little luck ours won’t break so easily.
Things aren’t so critical at the other end, however, where much of our effort has been going lately. The tail cover lay about gently fizzing for a long time until we eventually got around to sorting it towards the end of last year. It was a messy thing to dismantle but nothing we’re not used to. Rob and the boys did a fine job of tearing it down.
Next it was meticulously stripped of every trace of paint and corrosion by Novie and the Coniston Connection before the whole crew threw themselves into putting it back together again.
First it was built on a tool so we could access every crevice to build the necessary doublers but the tool doesn’t properly represent the lower half of the boat so we’d have been daft to not do a second round of fettling on the hull itself.
We were vindicated in doing this because the off-tool part simply didn’t fit anymore and we had to modify a number of new parts to get all the fixing bolts aligned and get it fastened down without building a world of residual stress into it.
I remember a story told to me by some of the engineers who’d worked on the first Panavia Tornados. They built the sections on the jigs and were all very pleased with the result but once released the parts sprung so badly that they needed hydraulics to get them back on again for the necessary mod’s.
With this heeded we elected to build the tail cover on the boat after Bettablast had painted everything to the usual standard and, though it’s tricky crawling about in there, at least we know it’s going to fit when we’re done.
Normal rules apply – green for new, silver for original and, as you can see, there’s not a lot of green in there and what there is weighs a scant six kilos so we can offset that by leaving out a single lead ingot should we need to but in reality this small addition so far aft will help rather than hinder.
With its fresh surface coating, new rivets and the astonishing adhesive properties of choccie sauce, not to mention the additional strength conferred by the new doublers, it’s well on the way to being stronger than it ever was and very proud of it we are too. It’s also been a great learning experience and the processes for drilling, deburring, removal for choccying then refitting ahead of a rivet team are slick as can be now so the logical progression was to erect the engine cover in the same way.
There’s more of it, certainly, but it’s just more of the same so anyone with a pressing desire to learn to be a riveter is more that welcome to give us a shout.
Next on the list, apart from the several thousands of rivets needed to hold things together, we have some bits to add to the intakes, namely the duct liners and the sealing rings around the back where it attaches to the engine so we’ll be on with those shortly. And we have the rest of the fuel system to plumb together and the air system to work up to its correct delivery pressure. We’re also in comm’s with several companies about producing our new planing wedges for the sponsons. They have to be just right or nothing will work when we get back to the water so there’s still plenty to go at. Hopefully we’ll get to do a few extra updates and pop out a DVD or two because it’s been a while so until next time, thanks for your ongoing support and don’t forget to keep watching.