SimonBrown

18 hours ago, andym said:

Who is the manufacturer of the GPS kit, out of interest?

Finnish company. See here:

http://deep3d.co.uk/2020/02/04/accuracy-defined/

And here:

http://deep3d.co.uk/2020/02/10/from-here-to-there/

By applying a little cunning and guile to the set of data I shot back in December I managed to get the entire western section to build into glorious 3D:

https://sketchfab.com/3d-models/hankely-common-atlantic-wall-extended-bd6a8a1d0ed145f6b533f06b9eb1b47f

16 hours ago, daleheywoodtanks said:

Simon.

Here are the measurements you asked for. Sorry it took so long.

Many thanks for these. Once the latest model has finished running I will check the actual vs model values.

16 minutes ago, andym said:

Let's see if this works ...

Yes!

Thank you...

Many of you will know I'm into a) armoured/tracked vehicles and b) underwater photogrammetry. I also err towards doing stuff with accuracy and for topside models I like to use GPS to drive the accuracy and location of what I scan.

Up until now underwater GPS has been, to put it bluntly, a bit problematic. Radio waves don't penetrate the water and us divers can't use it.

Until now. Last week I was working with the Finnish manufacturer of an underwater GPS positioning system. Its a seriously good bit of kit - still beyond your average diver but very cost effective.

Anyway, I ended up scanning an AFV432 hulk. I have scanned it before, but did it again using the GPS feed to locate the cameras and scale the model:

https://sketchfab.com/3d-models/vobster-quay-afv432-3d4821a40fe44b4283068062a3a0e9eb

I could do with verifying the scale/size of the model - some check dims work out to be plus/minus 3% or thereabouts - but does anyone have a 432 close by and wouldn't mind running a tape measure over theirs for me?

Done and supported with my thoughts and reasons as to why this museum should exist.

On 12/21/2019 at 3:28 PM, BC312 said:

There is a lot of blown hull parts, i think from a Churchill at the entrance to the pit and one big chunk along the road to the mast on the brow of the hill. 

Chunk of armour with hand for scale.

This welded chunk is by the entrance to the pit and has taken a few hits in its time. 

Missed the big chunk near the brow of the hill. 

Whilst fully respecting its not much to go on...any guesses what this section is from?

This is good news. Best of luck with the application. Being relatively local it will be great to see the museum up and running.

The Chieftain will always be a work in progress...

On 12/17/2019 at 11:35 AM, BC312 said:

Weavers down at the back of Longmoor camp had two massive demolition pits, one filled in years ago but the place is littered with bits of tank armour wheels etc. The used to blow up tanks to test charges and armour and most probably see if it was feasible to repair at the workshops at Bordon. God knows what went into the filled pit.

Recently a couple of years ago the cadets were digging in at Weavers down and came across a metal lump in the ground and found a Churchill tank buried along with others in various states which Bovington took some away, the remaining they didn't want they just reburied. 

This would fit - someone had been digging and uncovered part of what looked like armour that had taken a hit from AP.

I really must take a ride out that way soon and see what's there.

On 12/17/2019 at 11:35 AM, BC312 said:

Weavers down at the back of Longmoor camp had two massive demolition pits, one filled in years ago but the place is littered with bits of tank armour wheels etc. The used to blow up tanks to test charges and armour and most probably see if it was feasible to repair at the workshops at Bordon. God knows what went into the filled pit.

Recently a couple of years ago the cadets were digging in at Weavers down and came across a metal lump in the ground and found a Churchill tank buried along with others in various states which Bovington took some away, the remaining they didn't want they just reburied. 

Duplicate! Doh.

I needed to test something for photogrammetry and rather than scan my garden for the nth time I nipped over to the Hankley Common Atlantic Wall. 

This is just the mid section:

Hankley Common Wall in 3D

If and when I get time I will scan the rest of it, plus see if I can't find and scan some of the other remains lying on the common.

Been busy working on a 3D recording project and the 1940s pillboxes make a great test subject.

Its a bit techie, but does have a lovely 3D model and ortho photo (be sure to zoom in) of a pillbox sunk into a Bronze Age barrow:

Pillbox in a Bronze Age barrow

The location of this pillbox is on a pretty flat plateau. The barrow, rising up all of a couple of metres at most, provided some banked earth protection.

8 minutes ago, Surveyor said:

Out of curiosity how long do these scans take, I appreciate depends on size of subject and environment dry land or underwater.

 

Very much depends on size, complexity and location.

This one took about 8 minutes to shoot the 224 images, 30 mins to sort and prepare for processing into 3D and then about a half day of computer time to actually process.

Underwater is an altogether different amount of time, varying from days to months to get the final result.

Can be done for less time, but compromise will always be accuracy, level of detail etc.

Well, in spite of not finishing the rebuild of the 21 inch 8-cylinder radial torpedo motor I seemed to acquired a second example...

This one is 18" in diameter and comprises of the motor, driveshaft and rear prop guards. It was lifted from the sea years ago and all the ferrous parts have corroded to dust, but the bronze castings are under the crud:

18in Torpedo drive train

Judging by the presence, design and material of the prop guards this one is likely to be a very early example and possibly an air-dropped variant - the kind of thing used by Coastal Command or hung under a Swordfish. Equally, it could have been from a destroyer or MTB and we do have the wreck of an MTB in Weymouth Bay.

I'm very unlikely to get the time to clean this one up and leaving it sitting on the drive is not going to happen, so I may be tempted to part with it - if there are any takers?

In no way can this be described as a military vehicle...but it is a defensive structure so hope its of interest...

I'm working on a project that is demanding a lot of testing of new techniques and methods, and the outcome of which is a level of accuracy and detail that has pushed some boundaries. Its all techie stuff so I won't bore the pants off everyone but basically it involves embedding GPS data into the image at time of capture.

This will explain in part why the 8-cylinder torpedo engine has taken a back seat and gone quiet.

Anyway, needing a subject to test on my thoughts turned to using the pillboxes that line the Basingstoke Canal as a reference and here you go:

Type 24 Pillbox

There are many examples tucked away in hedgerows fields around here, serving as a reminder of a battlefield that - thankfully - never was.

On 9/14/2019 at 8:26 PM, johann morris said:

Evening All,

For various reasons I have achieved jack since my last post but this afternoon I managed to  finally complete and connect all the brake, steering linkages. How efficiently it will all work, is yet to be seen and I still have to machine the ratchet teeth into the quadrants.

Jon

 

Seeing this dug into the memory banks...

I worked on a modified AFV432 project at RARDE Chertsey a long time ago. The K60 engine had been removed and a 6-cylinder Cummins unit with variable geometry turbocharger fitted to the crew compartment.

The driveshaft ran forward into the steering box...right past the driving position. The tank shop foreman insisted we made up a guard that would retain the driveshaft in event of any failure of said shaft. It was a very substantial hooped bracket.

In due course the driveshaft did fail whilst the engine was under max load...had the guard not been there to restrain it the damage to the driver would have been described as "life changing injuries" as it flapped around unrestrained.

Looking at that driveshaft running across the hull and its proximity to the drivers legs triggered this memory...and if you have not already done so...do please consider a guard or restraint to limit how much damage the driveshafts could do in the event of a failure.

Apologies if its already in hand, but it would be remiss of me not to share this experience I think.

Agreed. Slab Common used to be (might still be...not been there for a while) full of hulks used to practice recovery I believe.

This hulk was not there, but in an unusual location one would not normally associate with armour in the modern times.

So I will take a trip over there sometime I think.

On 9/4/2019 at 5:11 PM, MatchFuzee said:

Interesting to see how many have survived in the UK, from range targets to restored:-

http://www.armourinfocus.co.uk/a22new/register/thelot.htm

This entry caught my eye:

MkVII Bridgelayer

Recently unearthed south of Bordon Camp in Hampshire
In very poor condition but possibly to undergo a comestic restoration to provide a gate guardian.

Does anyone have any details on this? 

About 10 years ago whilst out mountain biking on the lands near Bordon I came across a small hole dug into the side of an earthen mound. In the hole was a large section of steel armour, possibly with a suspension mount, that featured the kind of hole only an anti-tank round can make when it does its job.

I had forgotten all about that until reading the above...I must go back and investigate soon.

1 hour ago, GforGermany said:

Something else: is this a size or a date?

Diameter and pitch of the prop would be my first check.

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.

On 6/6/2019 at 11:18 PM, BOBC1940 said:

Hi,

If anyone sees one of these pumps for sale as a mirror image of the one seen here please PM me, I might not see a new thread,  as its the type needed to recreate the worlds last surviving Albion AM463 350 gallon 3 boom refueller.

Duplicate post...

On 6/6/2019 at 11:18 PM, BOBC1940 said:

Hi,

If anyone sees one of these pumps for sale as a mirror image of the one seen here please PM me, I might not see a new thread,  as its the type needed to recreate the worlds last surviving Albion AM463 350 gallon 3 boom refueller.

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?

21 hours ago, terryb said:

yes, 4 bolts and its off!

technically it will not be legal to road register as it only has a single line braking system which is shared with the parking brake, but VOSA may not be aware of that.....................

Gotcha. Good to know and thank you.

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?

On 5/24/2019 at 8:44 AM, rory57 said:

Interesting project! 

The inlet valve has the very thick stem because the inlet gas is at quite some pressure. This pressure produces a force acting to push the valve open that is proportional to the area of the back of the valve minus the cross sectional area of the valve stem so a fat stem much reduces the required valve spring strength.

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.

Quote

The torpedo carried air at up to 3000psi which was supplied to the engine at approximately 800 psi as I understand it . Hence no need for a blower.

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.

Quote

But back to the main subject, - out of the blue, I have also been offered a Japanese torpedo engine for the museum.  It happens to be an 8 cylinder radial unit with an 18 inch diameter.  This was a bit of a surprise, as I have not seen any references to it. 

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?