Some of the earlier threads on PaperModelers.com got me looking at the Gun Carrier again. The drawings I found on the 'net didn't seem to fit the overall dimensions posted elsewhere. I found a couple of good side views, scaled them to the published dimensions and made some drawings. Then the simple solid forms from the drawings. The attached photos show the process and the resulting 3D model. The 3D model view image is updated from the one I posted on papermodelers.com)
I could use some help with the interior, which does not show up on any of the vintage photos I have found so far. Also photos of any of the plastic/resin models currently on the market would help as well. Those models were based on (1) drawings or (2) vintage photos; it would be nice to know which.
Since recent builds of my models have been upscaled, I started this in 1/48 scale.
This might lead into doing the guns that it was supposed to carry, but that will have to wait. (sorry, Charlie)
Updated views of the 3D model are attached. I still need help with the interior - drawings or photos. I will use photos of the available kits if we find nothing better.
We have no photos of the interior of the "box" so far, so I don't know what was used in the real things. It makes sense to me that there would be stiffening of some sort, but what kind? The interior had to be pretty open, so I am assuming for now that the "box" was primarily stiffened externally by the "T" sections we see on the top. Maybe we can use the ammo storage/fuel tanks/radiators to help some; I was thinking of making these three a single piece on each side. The rear plate, with the twin doors will also help stiffen the rest of it. thoughts? Maybe a couple of transverse ribs under the top?
Fletcher states in his article that the GC carried 60 rounds for either gun (6" or 60 pdr) in drums, 5 rounds per drum.
That is 12 drums, and I assume they were arranged 6 on each side.
If the rounds had no cushion surrounding them, the drums could be only some 17" or 18" in diameter.I can fit 6 on each side, snug, but they do fit.
If I put a 1" thick cushion around each round, the minimum drum diameter is 21" and fitting them into the available space becomes a problem.
Besides the ammo, there is a 30-gallon fuel tank (4 cubic feet), radiators and a fan/blower.If we stuff 6 #21" drums in, there doesn't appear to be space for the fuel, etc.
Question:what sort and thickness of cushion would likely be used for these stored rounds?... particularly the thickness?
Also...
Laying out the interior of the "box" has been an interesting exercise.I modified the engine shown on the Julio Pillet drawing to match the "standard" engine set shown in the MkIV Osprey book and the Great War Tank users manual.This included moving the exhaust off the center line, similarly to the MkIV.The fuel tank is only 4 cu ft, so it would be much smaller than Julio shows it, but the radiator needs to be larger and also needs a blower (fan).I haven't figured out a good bracing scheme yet; that will probably wait till the beta test builds.
I agree with the analysis of the ammo drums - if the drums are circular cross section. If Fletcher is right, and he is rarely wrong, 5 rounds per drum suggests to me a square cross section.
If the 127mm rounds are touching then the drum would be about 307mm side. With 25mm spacer, say something like a felt tube (wall thickness = 25mm) the side length is 357mm (14inches). With 6inch rounds the side length is 483mm (19").
That would fit ok. I don't know whether the classic waxed cardboard tube was used for ammunition - that might have been a WW2 thing. I'd guess the rounds would be transported without fuses and these screwed in just before loading the projectile.
Edit - thinking about it some more I believe the issue is of the semantics of Fletcher's term "drum" - I think we immediately (mentally) jump to cylindrical shape but in reality such a shape isn't very practical for transporting ammo. For example how do you get a round out of the "drum", the rounds are about 40kg (for the 6inch) - a top opening box seems a more logical container for the rounds.
Regards,
Charlie
-- Edited by CharlieC on Wednesday 28th of May 2014 07:34:50 PM
I think if Fletcher had meant the ammunition storage containers were not round he would have used a different word from 'drum', which always connotes roundness. If they were square he would have written 'box', I'm sure.
Although this drawing is of an apparent alternative Gun Carrier meant for lighter guns, Fletcher refers to the round objects as 'drums'...
I would have thought so too. I was responding to Wayne's observation that cylindrical drums give him difficulties in fitting the correct number into his model.
In an ideal world there would be an example of a perfectly preserved ammunition drum with provenance but we're unlikely to have that so we do the usual
flounder around hoping to approximate what existed 100 years ago. I'd guess the drums were a standard artillery item - surely someone knows the dimensions.
Do we have dimensions and photos of the ammo storage in the 6" howitzer caisson? That might help determine the space required in the CG drums.
One of the other threads today reminded me that we have a photo of the 60pdr caisson. I measured the width in the photo, proportioned it for the dimension given in the same handbook, and scaled the compartments to be 6 5/8 inches square. If we can find a similar photo for the 6", I can get at least a rough idea of the compartment size from it.
Also, the photos in the MkIV handbook don't show how the radiator/blower worked. The GC had two radiators, one on each side, so I will assume they are both half the size of the one on the MkIV. The MkIV blower looks like it might be situated on top of the radiator - not sure how well that would have worked. Also don't see the blower air intake. I'll keep poring over the pics and see what more I can deduce from them.
There's an interesting image in the thread on the 60 Pounder. In the centre of frame is a fusing station with 5 rounds, one on the stand and 4 beside it. Pity the gunner was a neat
freak and tidied the drum away before the photo was taken. I'm sure I've got a manual for the 6inch howitzer - may take some finding though.
The model is looking good, you've obviously been putting in some hours on your model.
I've noticed you haven't put the grills either side of the rear doors on yet, is there a reason for that? I was going to call them 'Vents' for the radiators, but as they have a mesh and the radiators have blowers, I'm thinking they are where the air is sucked in. Only guessing on that though.
MK1 Nut wrote:I've noticed you haven't put the grills either side of the rear doors on yet, is there a reason for that? I was going to call them 'Vents' for the radiators, but as they have a mesh and the radiators have blowers, I'm thinking they are where the air is sucked in. Only guessing on that though.
Helen x
Not quite, according to David Fletcher in his W&T article:
I have to say, CharlieC, that the more I ponder it, especially in light of your comments, the more sceptical I become that drums of ammo were stowed inside at all. You've got the engine and transmission taking up the entire central portion of the machine inside the rear housing. That housing is only open at the front in the middle portion, a sort of 'arched' opening, which means somehow lifting those heavy (nigh on quarter-ton) ammo drums over the engine and then sideways onto the 'shelf' formed over the tracks. And the drums can't have gone all the way to the rear of the housing because the radiators were positioned over the tracks there, so there isn't even that much room for them anyway. Having said that, I do agree with Wayne above that along with the fuel tanks and radiators, the ammo drums were likely to be arranged as he depicts them in his excellent drawings - it certainly makes sense. My problem is not so much with how they would have fitted but how they could have been practically manhandled into position.
I notice that in his W&T article, David Fletcher states that the ammo drums were '...intended [emphasis added] to be stowed within the rear part of the vehicle, above the tracks on either side.' Perhaps I'm reading too much into what may only be a stylistic quirk when Fletcher writes 'intended', but I do wonder whether, in practise, this method of stowage was found to be impractical for the reasons CharlieC outlines, and that this explains why Gun Carriers are pictured festooned with ammunition stacked up in the gap between the drivers' cabs and the rear compartment housing? In that case, it isn't extra ammunition, as has always been supposed, but rather it's the whole complement of ammunition being carried.
-- Edited by Roger Todd on Saturday 31st of May 2014 04:07:10 PM
I haven't gotten to the rear face of the vehicle, except to size and locate the oval doors. The isometrics show a fan and box radiator on each side. The flat surface of the fan aligns with the vent in the rear face. I assumed the air was drawn in from the inside of the box. The arrangement of the piping between the engine and the radiators is pure supposition, guided by the way it was done in the MkIV.
Perhaps the drums were installed once and left in place. The two small hatches, one on each side behind the ammo drums and below the fuel tank could have been used to pass ammo into the vehicle, one at a time, to be stored in the drums. I assume the compartments in a typical field artillery caisson were refilled in much the same way - one at a time.
Possible but why use the space inefficient drums to store the ammo? It would be easier and more efficient to have a couple of racks like the tanks had for the 6 Pounder projectiles.
I think the point of storing the projectiles in drums was to limit the amount of degradation of the explosive filling - WW1 explosives were nowhere near as stable
as modern explosives - in a container which could be rolled close to the gun before opening. See the comment I made on the 60 Pounder image a few days ago.
Even lifting and moving 45kg projectiles inside the GC superstructure would be a difficult exercise.
Don't understand at all. Drums for projectiles? Why? TNT and amatol were/are quite stable, especially when encased in the projectile (couldn't fire it otherwise), generally needs a booster to initiate reliably - but maybe not when enclosed in what is effectively a pretty decent pressure vessel. What about the propellant? Were those fixed rounds or did they use bagged propellant? Bagged propellant would be a whole different story, relatively 'delicate' (and much lighter). Don't want those flopping around under foot.
-- Edited by Rectalgia on Sunday 1st of June 2014 07:54:58 AM
I believe these were bagged ammunition. For the 60 pdr, the projectile weighed 60 pounds, and the propellant was 9 lb 7 oz of cordite per the Handbook of Artillery, page 195. Page 198 describes how two complete rounds are carried on the limber. Pages 199 and 200 describe the caisson and storage for 24 more complete rounds.
I've always found David Fletcher's style to be succinct and precise, especially in his earlier work. I would take him at his word - if he said "intended" that's what he meant - it never happened. Looking beyond the matter of the mass of the drums the logistics of moving them around in the superstructure would be nearly impossible even if there were a hoist and rail system on the roof.
I have to say I agree - I too find David Fletcher's writing very precise, and so I do assume that by 'intended' he meant 'intended' just as you expand on.
Another thought on handling the drums. They would fit through the rear doors, the ones David Fletcher wondered what purpose they served. Without inside photos or drawings, we don't know if perhaps there was a set of trolleys directly beneath the roof for moving the drums.
I am attaching updates to the iso views. I changed the drum arrangement again, this time placing them in a single, horizontal row and moving the fuel tank overhead. I added track plates, figuring I would try individual plates, sort of the way Shawn Dymond did in his builds posted on Papermodelers.com.
That would make a lot of sense - it could have been as simple as a couple of rails suspended from the roof perhaps with a telescoping section to clear the rear of the vehicle.
The model is coming along, albeit a tad slowly. The photos show the first build in progress. The pieces on the cutting board are for the rear superstructure. I have two transverse formers at roughly the third points, but nothing longitudinal yet. I hope to finish the superstructure shell tomorrow. So far all seems to be going pretty well. I have applied the hatches to the left cab, but not on the right one, and none of the other details.
More photos. The superstructure fits pretty well. I need to trim at front and back where the box meets the tracks. I have only one internal stiffener at this time. I will add another about half-way to the front face. The cross-girders at the front and rear of the bottom went better than expected; they do help stiffen the hull.
Another update. I am into parts fit-up testing on the engine set and the gun-handling system. Photos attached. I have started putting rivets and bolts on the parts. This is the first vehicle I've done that had a lot of parts on the inside.
That's looking very impressive Wayne - I'm clearing off a cutting mat in anticipation. Sorry about the lack of responses recently - I've had some bad shit happen
Thanks. This rascal has 12 pages of parts. I haven't counted the number of parts themselves. I have also not started the instructions, either. I am just now starting a complete white model with all the add-on detail parts. I have probably missed a few rivets and bolts.
More update pix. This is the left track frame. I won't put all the track plates on a beta build, but I did add some more details to the inside face after I finished this portion of the build.
That's looking really great, Wayne. Maybe some people would appreciate simpler tracks, but I think the individual ones very good; at least with a static model one can omit a sizeable portion of each track where it passes through the rear compartment and under the cabs.
The gun slide is done and most of the superstructure is now finished. I still need to add the rear mud/rock deflectors, a bunch of grab bars, the side boards and the hatches for all the openings. I opened up one of the rear doors after I had built most of the superstructure - messy - I recommend doing this before folding and glueing the sides. For the purists, yes I know I omitted the RAC flashes on the front horns; I have corrected this, among a number of other tweaks. BTW, the gun slide works, though the fit is a bit tight.