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

[Sturgeon]

10 minutes ago, Toxn said:

It improves the TE of the composite versus one made of pure textolite. Remember that textolite has a TE of something like 0.39, but an ME of a bit over 2. HHA has a TE of 1.5 and an ME of 1.5.

 

Did they change the textolite TE? I don't recall that.

[Toxn]

55 minutes ago, Sturgeon said:

 

Did they change the textolite TE? I don't recall that.

That's just the numbers I have: 0.39/0.52 KE/CE TE (what an acronym stew!). Density of 1.85g/cm3

 

More knowledgeable people, please chime in.

[Sturgeon]

38 minutes ago, Toxn said:

That's just the numbers I have: 0.39/0.52 KE/CE TE (what an acronym stew!). Density of 1.85g/cm3

 

More knowledgeable people, please chime in.

 

I mean the math shakes out that it's about as TE as RHA while being more ME. And I'm using that for some of my arrays. I guess I was confused by some of the language you used earlier.

[Toxn]

20 minutes ago, Sturgeon said:

 

I mean the math shakes out that it's about as TE as RHA while being more ME. And I'm using that for some of my arrays. I guess I was confused by some of the language you used earlier.

No worries - when a sentence is more than 50% acronyms by weight the chance of useful information being contained therein is... marginal. And that's without factoring in my consistent failure to do basic sums.

[Dominus Dolorem]

 

East Oil company report no279.

 

The development of the new MBT is going smoothly. Our design team has finally sent the first images of the prototype currently under construction.

 

The tank has been designated the MBT1 Monolith.

 

The Monolith is intended to be able to take on any existing or prospective threat on the continent and also to act as the basis for a heavy IFV.

 

Spoiler

 

[Sturgeon]

OK so I did the figures on my gun today and I'm getting 5,000 ft/s with a 47mm diameter 7.5 kg APDS core, which gives me...

 

22.5" penetration at 2,190 yards on a 0 degree plate, or 19.1" penetration at 2,190 yards on a 60 degree plate.

[Toxn]

After throwing my toys out the window, here's the new approach:

So far we're looking set to have a 127mm main gun, make the armour specs and still come in under 40mt.

[Lord_James]

36 minutes ago, Toxn said:

 

So far we're looking set to have a 127mm main gun, make the armour specs and still come in under 40mt.

Millimeters? Metric tons? In Texas?! 

[A. T. Mahan]

I should be about 104,000-110,000lb

[Sturgeon]

On version eight point one of the turret and version one point thirty-four of my hull (don't ask), but we're getting there:
 

Current weight is 62.1 tons.

As a benchmark, I'm looking at about 585mm penetration at 2,000 yards on a flat surface, or about 495mm on a surface angled 60 degrees from vertical. The gun itself is highly silly, it's a 5inch (127mm) high velocity cannon and I'm getting about 5,100 ft/s with APDS. Muzzle energy (before sabot separation) is an estimated 28.7 MJ. Compare to the 120mm M58's 13 MJ. Nuts. Armor is 600mm RHAe vs KE throughout the 20 degree frontal arc on the turret, each side, and about 550mm vs the same on the front hull, through the same arc. Side armor is... silly. The skirts are 9 inches thick and made of NERA and fuel. Behind that is the suspension, another layer of HHA, more fuel, and then the hull armor.

The engine I'm working with is a bored-out AVDS-1790 which is getting an estimated 1,200 horsepower. An MTU MB 873 would also fit, with a little rearranging of cleaners and turbos and things, so the power density is by no means exceptional (check that fat ass!). With that engine and 6,666 lbs of internal fuel, I'm getting an estimated 901 miles of range. So, not bad.



"Well do ya, punk?"

[Sturgeon]

I wanted to give you guys a look at what the armor array is like:

[Sturgeon]

 

 

 

[A. T. Mahan]

 

Things are coming along nicely

[Sturgeon]

I met the 4 machine gun requirement by adding two belt fed remote controlled synchronized rate-augmented Owen CIWSes.

[Toxn]

One of the problems I've been having with generating a truly terrifying APFSDS is that longrods/LO/etc. is very bad at assessing the effect of cap design on penetrator performance.

 

For instance: simulating the performance of early soviet designs such as 3BM-12, the result that the formula spits out (after factoring in the contribution of the insert, using an armour hardness of 300 BHN and a penetrator hardness of 550 BHN) is almost correct: 279mm at 2000m calculated vs 280mm at 2000m measured.

 

On the other hand, 3BM-26 gets a measured value of 410mm but calculations imply that the penetration is slightly worse: 276mm.

 

This is using the provided rod and penetrator diameters, rather than the total masses and length. If we use known penetrator length and mass instead (and simply adjust the diameter to match the mass, keeping the cap as frustum length) then the estimated values for 3BM-26 get a bit closer to the mark (343mm at 2000m estimated) but still fall short by a large amount.

 

Does anyone know a more accurate formula for calculating these types of penetrators?

[Beer]

12 hours ago, Sturgeon said:

 

 

 

Sorry to jump into this thread while I don't take part in the competition myself but I have some questions. 

 

How do you assemble the armor arrays in these cavities (front hull and turret cheeks) or maybe better to ask how are those cavities made? They don't look castable at all to me. Are they welded from cast pieces? If so I can still see assembly of the special armor arrays as very inconvenient for a mass production if not impossible. 

[Sturgeon]

22 minutes ago, Beer said:

 

Sorry to jump into this thread while I don't take part in the competition myself but I have some questions. 

 

How do you assemble the armor arrays in these cavities (front hull and turret cheeks) or maybe better to ask how are those cavities made? They don't look castable at all to me. Are they welded from cast pieces? If so I can still see assembly of the special armor arrays as very inconvenient for a mass production if not impossible. 

 

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.

[delete013]

18 minutes ago, Beer said:

 

Sorry to jump into this thread while I don't take part in the competition myself but I have some questions. 

 

How do you assemble the armor arrays in these cavities (front hull and turret cheeks) or maybe better to ask how are those cavities made? They don't look castable at all to me. Are they welded from cast pieces? If so I can still see assembly of the special armor arrays as very inconvenient for a mass production if not impossible. 

It's actually plastic mould. But because entire N.America will know the thickness, nobody will be shooting at it.

[Sturgeon]

3 minutes ago, delete013 said:

It's actually plastic mould. But because entire N.America will know the thickness, nobody will be shooting at it.

 

I mean... It's textolite which is sort of like plastic. But this wouldn't be the first time you demonstrated that you know fuckall about armor technology!

[GregHouse]

49 minutes ago, delete013 said:

It's actually plastic mould. But because entire N.America will know the thickness, nobody will be shooting at it.

That's like saying that no one will ever try to shoot down a stealth aircraft because everyone knows how stealthy the aircraft is.

[delete013]

18 minutes ago, GregHouse said:

That's like saying that no one will ever try to shoot down a stealth aircraft because everyone knows how stealthy the aircraft is.

It took exactly one shot down F-117 to render entire fleet useless.

 

..besides, it was a joke.

[GregHouse]

1 minute ago, delete013 said:

It took exactly one shot down F-117 to render entire fleet useless.

 

..besides, it was a joke.

And yet they're still operating in the desert doing who knows what...

[Sturgeon]

19 minutes ago, delete013 said:

It took exactly one shot down F-117 to render entire fleet useless.

 

..besides, it was a joke.

 

Which is why no one flies stealth aircraft anymore, of course!

[Sten]

Stealth obsolete confirmed! 

 

Also LOS is not unreasonable for most competitors, specially given the ground pressure requirements. Maybe we should have used interleaving wheels as the master race figured out many decades ago.

[Sturgeon]

My tank's LOS is really not very excessive in the big scheme. It's like 8t heavier than an Abrams with inferior armor.