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


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7 hours ago, Sturgeon said:

Please note a minor rules clarification:

 

Formerly: Tungsten is available for tooling but not formable into long rod penetrators.

 

Now: Tungsten is available for tooling but not formable into long rod penetrators. It is available for penetrators up to 6 calibers L:D.

Including tip inserts for long rods?

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15 hours ago, Lord_James said:

Is glass textolite and/or fused silica available? The silica should be easy, the lone state has a lot of desert and coast line (and therefore, sand) in their territory :D

We always have this question (along with the inevitable exotic ceramics availability discussion) and it never amounts to anything in the end. NERA/ERA is just too good on a protection by weight basis to bother with inert inserts.

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1 hour ago, Toxn said:

We always have this question (along with the inevitable exotic ceramics availability discussion) and it never amounts to anything in the end. NERA/ERA is just too good on a protection by weight basis to bother with inert inserts.


Could have a judge who’s pedantic and brings up how ERA can be dangerous to nearby infantry... 

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4 minutes ago, Lord_James said:


Could have a judge who’s pedantic and brings up how ERA can be dangerous to nearby infantry... 

Firstly: NERA.

 

Secondly: the spec calls for 4 independent machine guns. This thing is dangerous to infantry regardless of whether it has explosive bricks on it or not.

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Please see this post for resources on what sort of guns the Texans are able to make:
 

The government of The Lone Free State of Texas and The Great Plains is currently engaging in research efforts to scale up the experimental 3-in G-41 L/59 to 4.7-in caliber, and also investigating the use of smooth bore guns to fire tungsten-steel alloy fin stabilized darts of 12:1 aspect ratio or finer. Tests of denser alloy long rods incl tungsten have resulted in shattering when aspect ratios exceeded 7:1, so it is recommended that any heavy metal elements be restricted to 6 calibers or less.

 

Quote

GUNS OF TEXAS

 

Encyclopedia of American Small Arms, 6th Edition

Vienna Publishing, 2241

Despite having no formal military, the Lone Free State of Texas has an extensive arsenal of sophisticated small arms and artillery. Local militias are provided a stipend with which they can purchase arms from the government, up to and including recoilless rifles of 105mm bore according to reports. It is therefore worth examining the weapons of the Lone Free State.

PISTOLS

 

The primary pistol of the Lone Free State is the G-36. This recoil operated semiautomatic pistol holds 15 rounds and has a barrel length of 102mm. Bore diameter is 10.2mm and it fires a 10x22mm round that was developed in the pre-war United States. Standard ammunition is semi-jacketed with a steel core, with both penetrating and expanding characteristics. The slide and barrel are both hammer-forged steel, while the frame is steel with polymer panels. Unusually, the gun is fired with a cowboy-esque hammer, and not a striker as has been ubiquitous for nearly two centuries. This pistol is commonly seen in Texas, as it is the best weapon available for purchase using government funds for local militias and landowners. At the same time, many local shops turn out boutique pistols of numerous varieties, all of which are broadly similar in characteristics to the G-36. In most cases, like the A1 version of the G-36, they provide a slot on top of the slide for a rugged reflector sight, which is commonly attached.

RIFLES

 

The most common rifle is the G-15. This is a 10-shot, manually operated rifle with provision for an optical sight, normally a robust 1-8x being attached. Caliber is the relatively antiquated 7.62x51mm. The feed mechanism is a sturdy steel box magazine which sits below the action of the rifle. Unlike most manually operated rifles of the Americas, the G-15 is lever actuated, not operated via a bolt handle. Texan shooters feel this gives them a superior rate of fire without compromising range, although it must be said this compromises prone and concealed fire capability. The G-15 is being phased out in favor of the newer and semiautomatic G-38.

MACHINE PISTOLS

 

Pistol caliber automatic shoulder weapons are uncommon in Texas, but the numerous police and paramilitary forces of the state occasionally use "sub machine guns" as they call them. Virtually the only model available is the G-32, which fires the same 10x22mm round as the G-36 pistol. It is a select-fire, closed bolt weapon using an unusual gas operated mechanism. Capacity is 35 rounds. Reportedly, it is very expensive and usually requires local funds in addition to the stipend to afford. Occasionally these weapons find their way into criminal hands, and they have also been seen in the possession of settler citizens who have legitimately purchased them.

STURMGEWEHRS

 

Offsetting the lack of machine pistols somewhat, the Texas government has aggressively pursued the sturmgewehr concept as part of their arms program. The latest of many Texan weapons in this class is the G-42, a gas operated select-fire weapon with a capacity of 28 rounds. Caliber is 6.86x40mm, and muzzle velocity is over 900 m/s. This rifle has been made relatively inexpensive due to a large production rate and widespread adoption by the settler population, who use it primarily for homestead defense and hunting. Like its manually-operated predecessor, it is compatible with optics, and usually is found equipped with the same 1-8 optical sight. Numerous other weapons, including pre-war designs both reclaimed and newly manufactured, are also used by various Texas citizens and militias.


MACHINE GUNS

 

Although there is not much need for belt fed machine guns in cattle herding (the primary trade of the citizens of the Texas countryside) the Texas government has procured significant numbers for border control and to combat bandits. Most of these are contained in armories at the various outposts and post offices that run along the country's substantial highway system, but some are held privately. Despite most belt feds worldwide being based on designs from over 200 years ago, many of those in the Lone Free State are original designs dating to within the last 50 years. This is exemplified by the primary Texan belt fed machine gun, the G-17A4, which fires an advanced high pressure steel cased 7.62mm round with either an open or a closed bolt operation. Most remarkable is its weight, which is just over 8 kilograms. Stocked infantry variants, as well as more numerous fixed/vehicle stockless variants both exist. Texan heavy machine guns still fire the 322-year-old 12.7x99mm round, albeit in a greatly augmented form. Like the smaller 7.62mm machine gun round, it uses a steel case and relatively high chamber pressure of 4800 BAR, which results in a 3,150 ft/s muzzle velocity with its 750 grain armor piercing explosive projectile. The principal machine gun in this caliber is the G-19A2 which is gas operated and utilizes a soft recoil system and has a rate of fire of approximately 500 rounds per minute. These machine guns are usually seen mounted to government G-12 4x4 armored cars.

 

AUTOCANNONS

 

Only in the past 15 years as the Lone Free State invested heavily in autocannons. For most of its post-war history, there were simply not enough targets that required automatic cannons, with very few armored ground vehicles and aircraft being operated by non-state actors in the Texas region until recently, to necessitate development of new weapons. However, as the Lone Free State has expanded, it has begun to encounter better organized and armed natives, necessitating the development of a standardized suite of new large-caliber autocannons. Chief among these is the electric G-37 firing a 30.5x114mmB round with a muzzle velocity of about 820 m/s and a rate of fire of about 550 rounds per minute. Interestingly, this cannon is capable of being mounted on any of the same pintle mounts as the G-19A2, giving light Texan units potentially very good firepower.

 

RECOILLESS ARTILLERY

 

Despite not seeing the need for autocannons for many years, the Lone Free State has liberally used the recoilless artillery concept, with most local militias possessing some stockpile of recoilless weapons. Numerous variants of recoilless rifle exist in three primary calibers, 57.2x305mmR, 76.2x406mmR, and 105.4x610mmR. These recoilless cannons are commonly mounted to the light helicopters used by various Texan government entities.

 

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{Sidles up to the bar at a nondescript neo-revivalist saloon, motions you to a quiet table after pretending to meet you}

 

Okay, so I've heard that you're also an engineer from "across the citrus curtain" and are still getting used to life in boots instead of skirts. That's fine, there are more of us than you'd think. But since the locals use some sort of ancient, impenetrable script instead of an actual system of weights and measures, I figure this might help you get your bearings:

 

Protection:

  • The protection standard against enemy HEAT is fairly laughable, given what we know the Mormonhadeen are packing thanks to the Cascadians. The "6 inch" projectiles being used as a reference hit like ancient panzerfausts and can punch through around 180mm of RHA on the flat.
  • The protection standard against KE is much more up-to-date, and obviously reflects a run-in with (or espionage against) the new Cascadian Norman tank. The "4 inch/54 calibre" gun is actually the 105mm L/51 gun off the Norman. The relevant penetration figures are 263mm RHA at 1800m, and 394mm at 1100. I'd suggest leaving some growth potential in the hull and suspension for when the Cascadians re-discover APFSDS.
  • The other protection requirements are more or less self-explanatory, provided you can multiply by 2.54.

 

Firepower:

  • The firepower requirements get interesting once you consider the option of low-pressure or high-pressure shaped charges. Low-pressure HEAT (similar to the pre-war 90mm Cockerill guns) can beat the low-penetration 13" requirement using a ~76mm tube, and the high-penetration requirement using something in the 85-100mm range. The high-pressure guns can beat the low-penetration requirement using an 85-90mm tube, while the 15" high-penetration requirement can be handled by a gun of about 105mm. So our new Texan employers are essentially asking us to clone the Cascadian gun.
  • In terms of maxing out the firepower requirements, it looks like Texan loaders can't sling much more than Californian ones: around 25kg. The weight of a one-piece round is obviously variable (and depends on the type of projectile, its velocity and the composition of the cartridge case) but using 100mm UOF-412 as a reference you're looking at a maximum calibre of something like 80-90mm in order to allow loaders to sling full-bore AP and HE. If you instead limit yourself to HEAT-FS you're looking at 100-105mm guns. Going further and looking at APFSDS, you could probably get up to 120-130mm weapons.
  • If you use separate shells and charges, then the maximum size of HE or solid shot that a loader can sling goes up to around 120mm. For HEAT-FS, this goes up even further to around 130-140mm. For APFSDS the issue actually ends up being the charge weight rather than the projectile weight. 

 

Mobility:

  • The range requirement comes down to a conversion factor of about 0.148 kg of fuel per hour per kW of power.
  • In term of the range itself: 483 (baseline) and 805 (desired) km or range is impressive, and represents functionally one to two days of unrefueled driving.
  • The power requirement is for 11.5kW/mt.
  • Put all the above together and you can very quickly scope out the limits of the design space. For instance: a T-55 analogue will need a 556hp/415kW motor to make the cut in terms of PWR. It will then need around 1355lb/614.5kg of fuel to make the minimal 300mi range requirement. This translates (using a density of 850kg/m3 for diesel) to around 0.723m3 of fuel storage, or 723 litres. Using the 500mi requirement, you need around 1200l of fuel storage (which comes to nearly 3% of the vehicle's total mass)
  • Looking at the ground pressure, this requirement seems to be based on a simple weight/track area calculation rather than MMP. The converted units come to around 95.8 kPa. This is fairly light, but certainly doable given the latitude we're allowed on width.

 

Anyway, I hope this helps you landing that contract. Us former Californians have to stick together, after all.

 

{Tips oversized cowboy hat to you, says goodbye in exaggerated Southern accent, walks out of saloon}

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Did I say CV90's big brother? I meant a (somehow) fatter M109: 

eyxA9ij.png

 

for perspective, the gun is an 6.1 inch (155mm), L/24 cannon, and the turret ring diameter is 86.6 inches (2200mm). She is currently sitting at 28.1 tons, and has 1 inch (25mm) base armor on all surfaces. 

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12 minutes ago, Lord_James said:

Did I say CV90's big brother? I meant a (somehow) fatter M109: 

eyxA9ij.png

 

for perspective, the gun is an 6.1 inch (155mm), L/24 cannon, and the turret ring diameter is 86.6 inches (2200mm). She is currently sitting at 28.1 tons, and has 1 inch (25mm) base armor on all surfaces. 


OH BOY I SMELL NERA

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Current state of my hull:

SZ6303U.png

I like designing castings in SolidWorks so that's what it is. NERA is kind of boring to design IMO because you just build boxes out of it and it's efficient enough that you can make big blocks at neutral angles and that works. Castings require (and enable!) a lot more use of compound surfaces etc to make them as efficient as possible. Of course, steel is also worse armor so that means I will be de-facto behind the curve vs the other submissions. Well, that's ok, I can't win anyway!

The engine I was going to use, the AVCR-1100 ended up being rather questionable, so we're likely to get an 8" lifted engine deck and a raked rear panel to fit an AVDS-1790. Should look tres cool and give it that nice "fat butt" look.

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This is the nth time I've revised the rear hull. Now it's got a nice raked back (52 degrees) look, and a raised deck. All of this to fit the fatboy AVDS-1790:

TshxRSH.png

7zbx1IJ.png

tenor.gif

 

I mentioned on the discord that this was based on a heavy tank hull I was working on a while back, but with every piece of geometry substantially changed. I wanted to compare the two side by side:

p3hFkdR.png

 

 

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1 hour ago, Sturgeon said:


OH BOY I SMELL NERA


Well, yeah, I’m not talented. Though I do plan on using special, non reactive armor in a place I think might benefit from it. 
 

 

In regards to the complex surfaces and whatnot, you could always take the T-72B route and cast it in such a way as to have a nice hollow space to place a couple layers. 

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