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  #21  
Old 03-20-2023, 06:37 PM
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CharlieC CharlieC is offline
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May I make a suggestion about the turret?

Turrets are complex pieces of equipment since they use a ring gear which is an expensive machining job and requires specialised machine tools. My thought is that the creators of this tank might well have reused the existing turret machinery of a tank in production and possibly used the castings of an existing turret as well. About the only tank in production in Spain at this time was the Trubia Naval which had a turret somewhat like the Barbastro design - as far as can be deduced from the images. There is a 1:50 model of the Trubia Naval around (see edit) which might help.

Charlie

Memory finally produced the goods - it's a Robototehnik model - https://vk.com/robototehnikpaper?z=p...01381877%2Frev
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Barbastro tank SCW-trubiaera.jpg  
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  #22  
Old 03-22-2023, 04:04 PM
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rockpaperscissor rockpaperscissor is offline
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Thank you for your continued interest and favorable comments, fellas. Thanks for your valued input, Charlie. I have that Trubia Naval model. It was a combo kit, paired with a Bilbao armored car. Both models were in 1/35 scale. There's not a lot known about the Barbastro tank, and much of the information just parrots what has already been written but, from what I've gleaned, the Barbastro metal workshop/fabrication facility was very well equipped and did have the capability of performing the fine machining that would be required to create a working turret.

In designing the turret for my model I referred to Trubia Naval turret, the (poor) period photographs, pictures of the available resin models, and a couple of illustrations from the internet. it is similar in some ways to the Trubia Naval turret but has unique features as well.

I had already determined the diameter of the turret on the hull, so to start the process I generated a B&W circle of that same diameter, and then enlarged the image enough (maybe 300%, perhaps more) that I could lay my plastic metric ruler over it to get a measurement in mm. I then multiplied that measurement by 3.14 to get the length of the strip required to wrap around the circle and drew a straight line of the appropriate length. Once I had the length of the strip established, I came up with a width that appeared pretty close to the B&W photo reference I use for this model and drew a vertical line from one of the corners of the initial line. I then drew two more lines, creating a long rectangle that would serve as the side of the cylindrical turret. From there it was a matter of generating details like the top hatch, and the side viewing ports. A round opening in the front will eventually hold a ball mount machine gun. There has to be some way to aim the machine gun, so I added vision slits on either side. I don't know if they were really there or not, but it makes sense. One of the resin kits has a square hatch on the top of the turret, but I didn't like the way that looked, so I made a much more appealing split round hatch that hinges on the sides. All of this is total guesswork on my part.

The turret is made up of 10 individual parts. I got a little bit ahead of myself and added texture and shading prior to the alpha B&W build as I did with the hull. Keeping fingers crossed that the turret will assemble as nicely as the hull.

The build experience will follow - probably tomorrow.
Attached Thumbnails
Barbastro tank SCW-build14.jpg  
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I don't always build models, but when I do... I prefer paper. Keep your scissors sharp, my friends.
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  #23  
Old 03-23-2023, 01:35 PM
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rockpaperscissor rockpaperscissor is offline
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I've successfully assembled the turret and took a photo every step of the way.

The photo in the previous post contains a 1/16 inch/2mm thick beer coaster which I glued the top and bottom turret formers to. Modeling tip: beer coasters make great bulkhead/formers/internal reinforcers. They are easy to cut, they barely warp at all, and are easily flattened back out if they do happen to warp a little. In the USA, bars and restaurants have been replacing them with napkins recently, so I grab them to add to my scrap cardboard stash whenever I find them.

To start the assembly I glued the top and bottom former pieces and hatch mount to the beer coaster, and while they were drying I cut out the turret ring, electing to remove the glue tab.

After punching out the round hole for the machine gun, I rolled the part and butt/edge glued it instead of overlapping it.

Next, starting at the front, I glued on the widest strip which wraps around the bottom of the turret. This strip strengthens the delicate butt glued joint from the first step. Then I glued the second strip on top of it - this piece is a smidge long and had to be trimmed.

Again, starting at the front, I glued on the thinnest strip which wraps around the top of the turret ring, further strengthening the entire assembly - this piece also required a very slight trim for the best fit.

I glued the side hatches to the same cereal box cardboard that I used for the other hatches, curved them a tad, and then glued them in place on the turret sides. They are way too thick but are consistent with what I've already done.

I cut out the top turret former first and slid it in place through the underside. Important - for a perfect fit, when trimming the formers, cut away the outer black line. From the underside I applied glue all the way around the former/turret ring joint.

When the previous step was dry, I glued on the hatch mount and to that the hatch itself, which had already been laminated to the too thick cereal box cardboard.

To complete this subassembly, I applied a thin bead of glue around the bottom interior of the turret ring and slid it over the trimmed bottom former. I neglected to take a photo of this last step. Finally, I glued the completed turret to the hull.

I'm really happy with the way it looks. I hope you agree. Now, on to the last step - the suspension/tracks.
Attached Thumbnails
Barbastro tank SCW-build15.jpg   Barbastro tank SCW-build16.jpg   Barbastro tank SCW-build17.jpg   Barbastro tank SCW-build18.jpg   Barbastro tank SCW-build19.jpg  

Barbastro tank SCW-build20.jpg   Barbastro tank SCW-build21.jpg   Barbastro tank SCW-build22.jpg   Barbastro tank SCW-build23.jpg   Barbastro tank SCW-build24.jpg  

Barbastro tank SCW-build25.jpg   Barbastro tank SCW-development5.jpg  
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I don't always build models, but when I do... I prefer paper. Keep your scissors sharp, my friends.
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  #24  
Old 03-23-2023, 03:10 PM
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dam thats awesome looking sharp well done love the design work youve done to get this far fine work
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  #25  
Old 03-23-2023, 04:07 PM
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Don Boose Don Boose is offline
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Fascinating to see this develop!

Don
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  #26  
Old 03-23-2023, 06:30 PM
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CharlieC CharlieC is offline
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That looks pretty convincing to me. The Trubia Naval seems to have had a one piece cast steel turret shell but I don't think the city of Barbastro would have had a steel caster and had to build the turret shell from flat plate parts.

Charlie
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  #27  
Old 03-24-2023, 06:41 AM
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rockpaperscissor rockpaperscissor is offline
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I'm sure you're right about that, Charlie. I'd like to pick your brain on a couple of points - I think I've had a revelation: on both period photos there seems to be two bumps or protuberances on the hull, way up high just to the rear of the turret. At first glance it appears that there are three bumps on the period 3/4 rear photo, but I think the rightmost bump/shadow is actually the tank's far side door, which is open. These bumps appear to be about an engine width apart - hint, hint. Both of the resin kits ignore it/them completely. Rear view vision ports? Or possibly...exhaust pipes/covers! Based on the resin kits, I put the external muffler on the rear right hull, but I'm not comfortable with this placement. The Barbastro was powered by a Ford flathead V-8 located at the rear of the tank, so it would have required a real pretzel to plumb the pipes from the exhaust manifolds into a Y pipe and then out through the side of the tank where it is placed. I'm assuming traditional engine placement followed by the transmission and a very short (if any) driveshaft to the differential. It could be done, but it doesn't look like there was whole lot of room under/behind the engine to run all this plumbing and exit the exhaust out through the side of the tank. I'm thinking, maybe they simply ran dual pipes forward, and exited them up behind the crew compartment which would explain the bumps. Also, on the 3/4 rear photo it looks like there is some kind of plate located over the top of the engine. I'm thinking it's an air cleaner. I'd value your opinion (and anyone else who's following along as well) on my thoughts.
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I don't always build models, but when I do... I prefer paper. Keep your scissors sharp, my friends.

Last edited by rockpaperscissor; 03-24-2023 at 07:26 AM.
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  #28  
Old 03-24-2023, 09:02 AM
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SmashedGlass SmashedGlass is offline
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This is a fascinating process to watch
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  #29  
Old 03-24-2023, 10:11 AM
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Tapcho Tapcho is offline
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I think Miniairons got the rear wrong. To me the 3/4 rear photo shows the forms you created but without the mesh. That area being right on top of the engine the thing seen in the photo could well be an air cleaner. Would make sense since the ' exhaust pretzel' occupies the engine topside. I don't believe exhaust was taken through crew compartment wasting precious space from ammunition and providing too much heat to an already cramped space - so my vote for the bumps goes for rear vision ports.

Tappi
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  #30  
Old 03-24-2023, 12:58 PM
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CharlieC CharlieC is offline
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Just a thought but the Matilda Mark I was also powered by a Ford V8 and there's one preserved at Bovington. The Matilda has air inlets in roughly the same position as the "bumps" on the Barbastro tank. The Matilda exhaust is at right rear of the hull but the exhaust pipe must go through some contortions to get there. The Matilda also has mesh over (I presume) the cylinder banks in much the same position as the Barbastro has some sort of grill (*). I know I'm arguing that function defines form but the hulls on these tanks didn't have a lot of volume so there may not have been many choices in mounting a Ford V8 engine.

I noticed when adding the Matilda images the rear deck of the Matilda is sloped down in much the same way as the Barbastro tank. Perhaps this reflects the internal space requirement for the engine and transmission.

Charlie

* - edit - not certain but the mesh on the Matilda seems to cover large air inlets - perhaps the tank used a pair of radiators on each side of the engine.
Attached Thumbnails
Barbastro tank SCW-matilda-i-tank-side.jpg   Barbastro tank SCW-matilda-1-tank-rear.jpg  

Last edited by CharlieC; 03-24-2023 at 01:25 PM.
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