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COMPETITION Steel Chariot of The Prairie: The Lone Free State's First Battle Tank (2247)


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3 hours ago, Sturgeon said:

 

The arrays are made beforehand and then cast-in. Does it look like a pain in the ass to do? Absolutely. As a modeling project, it's a lot of fun however. I've learned a lot about using the "intersect" feature. It's worth noting that a number of Soviet tank designs did this very thing, so it's not unprecedented.

The alternative to casting them in, as you already guessed, is to have a bunch of castings glued together in a weldment around the arrays. But I don't find that nearly as fun to think about, conceptually.

Obviously, the reasonable thing to do would be to make yet another NERA box tank, but that's boooooooring.

 

AFAIK the Soviets didn't make it cast-in because it's impossible (better to say you can do that with sand rods like in T-72A/M but not with NERA array). They simply cast an opened pocket, put the special armor array inside and welded a cover on top. There are plenty of reason why it is impossible. 

 

- Temperature of the molten steel is around 1600°C. In such temperature your special armor array would partially melt (rubber for sure) and partially go through very extreme heat treatment which would definitely ruin its properties. 

- Cast steel has high shrinkage ratio around 0,5% at these distances. Anything closed inside which is not extremely rigid would be simply deformed by the shrinking material and anything rigid enough (thick ceramic for example) would bring high internal stress in the steel (personal experience with overmoulding of different materials - in my case combination of steel and plastic - even overmoulding of steel by plastic is not that easy thing). 

 

From other things I see other issues. Cast steel has low flowability (lower than cast iron). It requires relatively higher thickness/to length ratios and thicker sections need to be near the gate. If you make something like a rectangle of two thick walls connected with two thin walls you can not fill it without having two gates for exmaple. 

 

Uneven thickness also inevitably causes uneven cooling which results in deformations of the walls. 

 

Don't get me wrong but for me your design is not feasible for casting. 

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38 minutes ago, Beer said:

 

AFAIK the Soviets didn't make it cast-in because it's impossible (better to say you can do that with sand rods like in T-72A/M but not with NERA array). They simply cast an opened pocket, put the special armor array inside and welded a cover on top. There are plenty of reason why it is impossible. 

 

- Temperature of the molten steel is around 1600°C. In such temperature your special armor array would partially melt (rubber for sure) and partially go through very extreme heat treatment which would definitely ruin its properties. 

- Cast steel has high shrinkage ratio around 0,5% at these distances. Anything closed inside which is not extremely rigid would be simply deformed by the shrinking material and anything rigid enough (thick ceramic for example) would bring high internal stress in the steel (personal experience with overmoulding of different materials - in my case combination of steel and plastic - even overmoulding of steel by plastic is not that easy thing). 

 

From other things I see other issues. Cast steel has low flowability (lower than cast iron). It requires relatively higher thickness/to length ratios and thicker sections need to be near the gate. If you make something like a rectangle of two thick walls connected with two thin walls you can not fill it without having two gates for exmaple. 

 

Uneven thickness also inevitably causes uneven cooling which results in deformations of the walls. 

 

Don't get me wrong but for me your design is not feasible for casting. 

 

Nah, it's fine.

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12 minutes ago, Sturgeon said:

 

M1A2C. My tank is sitting at 72 m.t.

 

In the immortal words of Dos Gringos, that's a huge bitch. Looks pretty, though, the turret is giving me M60 needlenose vibes.

 

I'm working very hard to keep it under 100,000lb cause I want that sweet sweet PWR, and I've only got about 1175hp to play with. 

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18 minutes ago, A. T. Mahan said:

 

In the immortal words of Dos Gringos, that's a huge bitch. Looks pretty, though, the turret is giving me M60 needlenose vibes.

 

I'm working very hard to keep it under 100,000lb cause I want that sweet sweet PWR, and I've only got about 1175hp to play with. 

 

In terms of the field here, my tank is middling weight.

 

Starting engine is 1200hp bored out 1790 equivalent, with upgrade to a 1500hp MB 873 equivalent.

 

What drove the mass largely was the highly festooned hull, which is a bit bigger than usual and as you can see well protected by eleven ton side skirts. Height is 2.8m so nothing exceptional.

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I think this is the farthest I've managed to get in a competition (by how many necessary components I've completed). 

 

wqLMaeh.png

 

She's up to 44.8 tons, but I know I can get that down... each individual wheel is 540 lbs, which seems high... the tracks are also about 2.5 tons each (dont know how heavy they're suppose to be). 

 

 

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31 minutes ago, Lord_James said:

I think this is the farthest I've managed to get in a competition (by how many necessary components I've completed). 

 

wqLMaeh.png

 

She's up to 44.8 tons, but I know I can get that down... each individual wheel is 540 lbs, which seems high... the tracks are also about 2.5 tons each (dont know how heavy they're suppose to be). 

 

 

 

o9E5q5c.png

I recommend the Diehls.

My wheels are based on the US specification (used in more or less the same form from M48->M1), and they're 60kg per wheel. Two wheels per swing arm, eight roadwheels per side on your tank, that's about two tons.

If you take your armor weight and divide it by 0.55 you should get a good minimum all up weight value. If you don't reach that weight, time to look for things that may be too fragile (like suspension).

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2 hours ago, Sturgeon said:

 

o9E5q5c.png

I recommend the Diehls.

My wheels are based on the US specification (used in more or less the same form from M48->M1), and they're 60kg per wheel. Two wheels per swing arm, eight roadwheels per side on your tank, that's about two tons.

If you take your armor weight and divide it by 0.55 you should get a good minimum all up weight value. If you don't reach that weight, time to look for things that may be too fragile (like suspension).


I based my tracks on the T142’s used on the later M60s. They’re the same 28 inch width with replaceable rubber pads. 
 

I’m think my wheels just need to have some geometry fixes, and my suspension arms are too long: right now, she’s sitting at 29.5 inch ground clearance! I also completely forgot to add idler wheels. 
 

The torsion bars themselves are 3 inches in diameter. I thought I saw that 3 inches / 75mm was a decent thickness for such things, but cannot find it again. 

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