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SimonBrown

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Everything posted by SimonBrown

  1. A chance to scan an Alvis Scarab/Acorn into a 3D model arose this week when I paid its owner a visit: Alvis Scarab/Acorn Charming little vehicle with a great history. The same owner has the Series III Carawagon and the results of scanning (for fellow forum member Robin) that will be processed and published soon.
  2. There are three of these vehicles on the SS THISTLEGORM? I know it doesn't help much...they are in 25m of water, are in Egyptian waters and a massive tourist draw to 1000s of divers... But if I can scan it - and there is every chance I will be back there - then I'm happy to help if I can. Whereabouts on the vehicle are they fitted? Failing that, I could scan the existing pump into 3D and then mirror it in CAD?
  3. Many thanks Robin & terryb for the words of wisdom. All good gen and thoughts. A few more questions: Registering and ex-MOD example for the road - any issues with Construction and Use? If I recall the rear body is held on with four bolts and can be quickly demounted - is this memory correct?
  4. Excellent thinking on why the valve stem is so fat...and whilst I think the reasoning is spot on, its worth bearing in mind the design of the engine. The inlet valves work the other way around to any normal internal combustion engine; The flat face of the valve would typically face the combustion gases. Not so in this engine...here the inlet gases are pressing against the flat face of the valve...so the large diameter spring is actually holding the valve closed during combustion/power stroke and the expanding gases inside the combustion chamber. Inlet pressure alone is exerting a force that would hold the valve shut in this case. Did that description make sense? Have a look at the photos in the 1st March post here: Inlet valves etc I hadn't realised just how unusual this is, until your really thought-provoking post rory57 - so many thanks for that. The more this engine is understood, the more whacky it gets. So far, everything I read hints at an inlet pressure of 160psi as supplied by the air tanks, regulated down from the 3000psi or so they were charged to. Interesting, as it appears there was a shift in design thanks to improvements in the strength and quality of steel to hold progressively higher pressures. More reading needed. Now that does sound interesting - got any pictures yet? That would make the number of 8-cylinder torpedo engines I know of go from 2 to 3 and it would be great to see what it looks like. My engine measures 20" over the cylinder heads, leaving just 1/2" as a sliding fit into the torpedo body. Be interesting to know what the 18" actually measures?
  5. This is a long-term project, but the nagging idea of owning and operating a Bv206 under consideration. Buying: What to look for? Known issues or faults? Track life/wear? When are they knackered? Types and variants. FFR an issue? Spares - prices and availability? Operating: Petrol vs diesel? Anything really whacky about either? Reliability? From what I recall, very good...but thats 20+ year info. Maintenance - engine & drivetrain - any issues? Maintenance - steering & suspension - any issues? What license is needed? Not steered by tracks, so not an H type? Genuinely interested...and would love to hear from current owners. With that, its over to the forum and its collective knowledge...
  6. Sure, understood. Irony and humour is one of the hardest things to convey on t'internet. There is a third and far more accessible vehicle on the upper cargo deck. I will dig out some images. Correct on the loss of life. Some of the RN DEMS gunners and ship's crew were sleeping on on the holds when the bomb landed, according to accounts at the time. Angus McLey's George Medal citation makes humble reading. Generally, divers are not messing around with the munitions. There are a few 4in shell cases that have had the base plate buffed up to reveal the crows foot, date of manufacture etc but for the most part divers have no idea what they are looking at, let alone fiddle with it. There are some 15" shells near the aft end of what is left of hold No 4 but with marine growth many won't realise what they are looking at. No 5. hold was crammed with boxes and boxes of 4in shells, and the seabed is littered with boxes and individual shells thrown from the wreck by the explosion. As long as its left alone underwater UXO is pretty benign and the depth of hold No4 & 5 generally limits the time most divers can spend here. Plus most dives are done with a guide leading a group around the wreck. Most divers swim by without realising its all there, or have it pointed out by a guide as they swim by. So in terms of risk, by far the biggest risk to loss of life is all due to the divers themselves and right at the top of the list is running out of gas. In the time I spent there I saw two individuals hanging off the dive guide's alternate air supply as they had drained their tank. The underwater world punishes mistakes quickly and thats before anyone has even realised there are tons of bang in the aft end of the ship. Ah yes, the Montgomery. If that lot ever high orders, the east coast of Kent and Essex will be a little different. The longstanding policy has been to leave well alone...if that is a sensible long-term strategy remains to be seen. I'm glad I do not live on Canvey Island. Could we leave the Thistlegorm alone? Aside from the munitions there are few comparisons between the two wrecks. One sits very challenging conditions, almost akin to very cold, liquid mud. One is located in tropical blue warmth. The location makes a dive on the Thistlegorm as about as easy as it can be and its a very popular dive. One day we had 7 boats moored alongside ours, each with 15~20 divers aboard and all doing at least two, possibly three, dives. Attempts to calculate the simple economic value of the wreck has been attempted over the years, but with that volume of tourists willing to spend hard foreign currency in what is a relatively poor country the chances of the Egyptians closing the wreck to divers is at best guess close to nil. Besides, most divers want to see the vehicles in the forward holds. Helps keep interest in military vehicles alive...which is no bad thing.
  7. I will almost certainly have some already. Give me a few days and I will have a look. This is going to be trickier, on so many levels...we would need an air lift and a grab to shift the several tons of debris they are buried under...the first job before tackling the matter of luggage would be getting the axle back on deck as none of the boats have a crane. Plus the sheer volume of WD40 needed to loosen those bolts is going to make the Torrey Canyon look like a drop in the ocean. Now, about those photos? If there is anything specific you really need to see then let me know and I can direct the camera accordingly.
  8. Well there are three others. Trouble is, all are in at least 20m of water...and two are mostly buried under a pile of Morris Commercial, BSA M20 motorcycles, the odd Lee Enfield rifle and aircraft spare parts. And there is a good chance they are BY3 F.B.E. They are all in the forward hold of the SS Thistlegorm in the Red Sea. Access for most is, I will grant you, practically impossible. But...I have heard some good news and that is a return to Egypt and the Thistlegorm in the early stages of planning. It won't happen for a few months, but when I am there I'm more than willing to scan/photograph the most accessible* example if needed? Just let me know and I will see what I can do. You can see a pair of the pylons that held the cargo of boats in place sticking out of the debris pile here: 3D model of debris pile in forward hold *The term "accessible" is still relative. Its quite tight in the forward cargo hold but can get to 3 sides of it.
  9. For those interested, this model shows the roof of the Carawagon in the raised position: Carawagon roof up More detail is needed and areas need refinement, so its work in progress.
  10. Part of Robin's cunning plan is to refer to another Carawagon example. Trouble is, its on another continent... Solution? Robin asked me to see if I could scan another Carawagon here in the UK. He put me in touch with the owner and I nipped along to scan it. Not only could I scan it, but with scale bars and reference I reckoned I could get a 3D model about as accurate as it could be. Which is what we have here: Carawagon in 3D The total estimated error is ±0.3mm overall. Which is far better than the original manufacturing tolerances I reckon. To that extent I think the scanned Carawagon wheelbase is 10mm out...my next visit will check that. There is more work as I need to sort the model with roof raised and to shoot more images of the front camo net. But the principle is proved. Then I can start pulling the ortho photos off each view. These are massive images at a scale of 1:1 so any measurement you like can be taken. I will post up some lower res examples in a bit to give folks an idea what I mean. Its a tough project, but rather touched Robin asked me to get involved.
  11. No. It was a scan only dive and it would have been an entirely different exercise to try and lift bits. Besides, folks tend to get a bit twitchy if you start interfering with live ordnance. Even if its separated and in bits. Chances are the really interesting bit - engine and drive end of the torpedo - may well have survived.
  12. Back in April I had the good fortune to dive a complete 21" torpedo that had been found during a recent survey. Naturally I scanned it but have been sitting on the 3D model until after the RN could pay it a visit and deal with the high explosive. 3D model of the torpedo The engine and drive train section, the air tanks/pressure vessel and the warhead had all become detached from one another. No idea of the exact Mk or age, but gut feeling says it was pre-war. Its now been blown up but digitally preserved.
  13. The good news is all of the wrecks listed as being for sale are designated as Scheduled Monuments. Ownership can be freely traded, but its a bit like owning a listed building - there is very little an owner can do without permission - and the laws of salvaging anything from the wreck are enforced. A group of divers were caught with some artefacts recently and the two that entered a guilty plea were fined £18,000 each. There is a wreck of the UB116*, a First World War submarine sunk in Hoxa Sound, has changed ownership several times since the 1960s when MoD sold it to a salvage company called Metal Recoveries. Eventually the wreck was sold to a private owner and upon their passing their heir inherited the wreck. The non-ferrous parts of the German warships like condensers, pumps and torpedo tubes were salvaged a long time ago. Today, the high value scrap would be the steel armour plate. Its 14" thick in places and is clean of radiation, having been cast way before the atomic age started in 1945. Known as "Low Background Steel" this stuff is in demand for sensitive medical and scientific devices, but its actual market value is unknown. It may cost more to recover the stuff than its worth...read on... When Cox & Danks finally wound up their salvage work and sold the wrecks in the 1930s it was estimated the company had lost around £10,000 over the years, or around £1.5m in today's money. A few years ago the Orkney Dive Boat Association did a rough calculation and reckoned sport diving - folks paying to see the wrecks - was worth about £1.5m per annum to the local economy. With the gift of hindsight it would have been a better long-term investment to leave everything where it was... So yes the wreck ownership can be transferred by gift, inheritance or sale. But in all honestly, what are you going to do with it apart from put the title deed on your wall? *Shameless plug - I wrote a book about this sub and if its piqued your interest heres a link: Story of UB116
  14. Jon - this is one of the finest threads running here. Nothing short of remarkable. Keep at it and don't let the obstacles grind you down!
  15. Progress has stalled a bit as I have been busy on other things Scapa Flow related. A week of frustrating-at-times diving proved useful with a few new finds, plus documenting stuff like the Anti Torpedo Close Protection Pontoons at Flotta: 3D model of a pontoon. But I shall be back on the torpedo engine tomorrow - fingers crossed. I have also taken a close look at an 18" example recovered from the sea. Its in a bit of a state but could be worth preserving. The steel has gone but lots of bronze parts remain. On the 18" engine the cylinder heads were steel and have rotted but it did mean I got one of the set-circular gudgeon pins out of the bore without so much as touching a spanner... The rust is all that remains of the con rod. It crumbled like dust so not sure this one will be a runner again soon...of note was the piston ring. They are made of bronze and have survived well, if a little caked in rust.
  16. Last call for brown envelope style offers before we put the torpedo engine on Fleabay...anyone mad enough to want one? Now is the time... And we also have a Mk23 21" dummy warhead available: We have no idea what is inside it, but its heavy. Open to offers before its disposed of. Just PM me.
  17. Having seen how popular the 8-cylinder torpedo engine restoration has proved, I thought I would offer a 4-cylinder example for sale here. We think its a Mk VIII engine, a four cylinder two-stroke diesel example that appears to be complete. It has not been raised from the seabed and is in pretty good condition. Its possible its never been tested, let alone used. I would add this to my collection, but a) SWMBI would start to question the sanity and b) its being sold to raise funds for an ongoing project. The project we are working on is the story of the stolen Hercules C-130 that crashed in the English Channel in 1969. Last year we found the crash site, so now its time to dive it and investigate...all proceeds go in the pot to cover boat diesel costs. Its bronze and heavy thus attractive to the scrap man, but we would rather it go to a deserving home. We are open to offers on this example of superb engineering. Collection will be from either Weymouth or NE Hampshire. Go on...you know you want it...
  18. Not much progress of late, but things are cleaning up nicely and the gummy preserving oil is coming off a treat. On the right, pot No 3 cleaned and lightly lubed and on the left pot No 4 waiting its turn. Most of the pistons have some light scoring on the skirt but nothing to worry about. A scrub with degreaser is shifting the muck and the rings are now free to move in the groove. Barrels have been given a dunk too: And the bores are pristine: Note the two oil grooves halfway up the bore. Only one is pressure fed via the external pipes, with the other not aligning to any oil way I can see. Thinking about the big end...if it ain't broke don't fix it springs to mind. Its clean, rust free and rotates smoothly. Plus another special spanner is needed to get to the large nyloc holding the big end together. So I'm inclined to leave it and clean/reassemble from this point. Its still a work of art though. Heres a side view: I think the 'F' stamp stands for 'Front' but I will know when I turn it over and see if the rear set of con rods are stamped. Here's a view looking down: You can just see the big end nut above the main bearing. Here's a closer view: Access is tight and I think a standard socket and extension is going to clash with the square section next to the main bearing. Its such a compact unit. Quite remarkable the power output crammed into a 21" diameter tube. The pan head screws are treated to a dunk in the ultrasonic degreaser before having a die nut run down to clean the threads and the inlet valves are coming up brand new. Takes about an hour per pot to fully degrease, with 3 down and 5 to go.
  19. I can only echo that. Keep up the good work!
  20. Isn't it just? A real joy to work on, if a little fiddly at times. A puller has occurred to me. There might be risk of the caps being pressed in so tight the threads strip, but a puller could work. For now, and unless I can find a good reason, the pistons will stay on their con rods. The true purpose of oil feed into the cylinder is not something I had considered, but the idea its spraying over the little end bearing sounds perfectly logical and given the power output absolutely necessary. I will have a look at it again when next in the garage.
  21. I did promise a while back some photos of the gudgeon pin-less design. Its not easy to get your camera in - even a slim one like an iPhone - but here goes... Two bronze or brass caps are pressed into the piston and retained via a split pin. The brass caps extend deeper than the piston skirt and into the area under the piston crown. The caps are fixed and do not rotate, but are machined with a large flat on the side facing into the crankcase: Under the crown of the piston and fixed to the top of the con rod sits a solid bronze semicircular shaft that extends beyond the con rod and over the brass caps. The semicircular shaft is machined so that the piston can rotate about this shaft on the brass caps. The internal Admiralty threads may be there for no purpose other than to help in a manufacturing process? The load from the piston appears to be transferred to the con rod directly to the semicircular shaft and the brass caps are then to keep the con rod in place, but transfer no load whatsoever on either the induction, compression or power stroke. Is like nothing I have ever seen before and the conclusion is space was at such a premium they dreamed this up to reduce the overall diameter of the engine. I would imagine it might clatter a bit when running...which seems odd as sound travels well underwater and it might alert a hydrophone operator something was starting up...thats guesswork at the moment though. How it comes apart - if it ever can - is today's conundrum. Right now I'm fairly relaxed as underneath the crowns looks clean and lubed, and no corrosion.
  22. Isn't it just? Its going to get better...read on... Been thinking about what to do with it once the job is done? Inclined to mount it under a thick piece of glass and turn it into a coffee table...or just leave it on its stand in the living room and marvel at it every day...chances are that idea will be vetoed quickly by SWMBI. Starting to clean things up and No 1 cylinder & parts have been degreased. The good news is the gummy preserving oil holding the piston rings in cleared up and the rings are now free: Still not turned my full attention to removing the pistons - One of the bronze bushes was pressed/tapped to see if it would move and the short answer is "Not without more force than available right now" so they have remained in-situ. The thread, in case anyone is wondering, is another Admiralty pattern (The thread chart here has been used many times - thanks MatchFuzee) 5/8" with a 20 TPI pitch. I am now thinking the bronze bushes are pressed into place as a one way trip and may prove difficult to press out again, as its likely there would never be a requirement to strip and service. The degreaser has worked its wonders. The barrel was left to soak while all the nuts and pan head screws went into the ultrasonic cleaner with a 30% degreaser/water solution: Now its cleaned off its pretty clear the barrels are plated on the outside, and its probably a nickel finish. I suspected this as when the inlet manifold unions unscrewed some of what looked like plating peeled off and galled in the threads. The plating is peeling as 70 or so years have taken its toll: Now, a nickel plated set of barrels is going to look simply jaw droopingly beautiful, 8 of them gleaming like new. But should they be replated? Or do we leave the patina? For now, an issue to set aside as there is still plenty to do elsewhere.
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