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


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The LORD was with the men of Deseret. They took possession of the hill country, but they were unable to drive the people from the plains, because they had chariots of steel.

The Book of Latter Day Saints, Ch 8, vs. 3:10, circa 25th Century CE


 

BULLETIN: ALL INDUSTRIAL-MECHANICAL CONCERNS

 

SOLICITATION FOR ALL-TERRAIN BATTLE TANK

 

The Provisional Government of the Lone Free State of Texas and The Great Plains issues the following solicitation for a new All-Terrain Battle Tank. The vehicle will be the main line ground combat asset of the Lone Free State Rangers, and the Texas Free State Patrol, and will replace the ageing G-12 Scout Truck, and fill the role of the cancelled G-42 Scout Truck. The All-Terrain Battle Tank (ATBT) will be required to counter the new Californian and Cascadian vehicles and weapons which our intelligence indicates are being used in the western coast of the continent. Please see the attached sheet for a full list of solicitation requirements.

 

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Submissions will be accepted in USC only.

 

 

Supplementary Out of Canon Information:

 

 

I.     Technology available:

a.      Armor:
The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a judge.
Structural materials:

                                                              i.     RHA/CHA

Basic steel armor, 360 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 4 inches (RHA) 8 inches (CHA). 
Density- 0.28 lb/in^3.

                                                             ii.     Aluminum 5083

More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness.

 Fully weldable. Available in thicknesses up to 4 inches.
Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE.
Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE.
Density- 0.1 lb/in^3 (approx. 1/3 of steel).

For structural integrity, the following guidelines are recommended:

For heavy vehicles (30-40 tons), not less than 1 in RHA/1.75 in Aluminum base structure

For medium-light vehicles (<25 tons), not less than 0.5 in RHA/1 in Aluminum base structure
Intermediate values for intermediate vehicles may be chosen as seen fit.
Non-structural passive materials:

                                                            iii.     HHA

Steel, approximately 500 BHN through-hardened. Approximately 1.5x as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 1 inch.
Density- 0.28 lb/in^3

                                                            iv.     Fuel

Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE.

Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE.

Density-0.03 lb/in^3.

                                                          v.     Assorted stowage/systems

Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE.

                                                         vi.     Spaced armor

Requires a face of at least 1 inch LOS vs CE, and at least 0.75 caliber LOS vs fullbore AP KE.

Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 4 inchair gap.
Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette.

Reactive armor materials:

                                                            vii.     ERA

A sandwich of 0.125in/0.125in/0.125in steel-explodium-steel.
Requires mounting brackets of approximately 10-30% cassette weight.

Must be spaced at least 2 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).

                                                            viii.     NERA

A sandwich of 0.25in steel/0.25in rubber/0.25in steel.
Requires mounting brackets of approximately 10-30% cassette weight.
Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.

The details of how to calculate armor effectiveness will be detailed in Appendix 1.

b.      Firepower

                                                              i.     Bofors 57mm (reference weapon) - 85,000 PSI PMax/70,000 PSI Peak Operating Pressure, high quality steel cases, recoil mechanisms and so on are at an equivalent level to that of the USA in the year 1960.

                                                             ii.     No APFSDS currently in use, experimental weapons only - Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS.

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

                                                            iv.     Texan shaped charge technology - 4 CD penetration for high-pressure resistant HEAT, 5 CD for low pressure/ precision formed HEAT.

                                                             v.     The subsidy-approved GPMG for the Lone Free State of Texas has the same form factor as the M240, but with switchable feed direction.. The standard HMG has the same form factor as the Kord, but with switchable feed direction.

c.       Mobility

                                                              i.     Engines tech level:

1.      MB 838 (830 HP)

2.      AVDS-1790-5A (908 HP)

3.      Kharkov 5TD (600 HP)

4.    Detroit Diesel 8V92 (400 HP)

5.    Detroit Diesel 6V53 (200 HP)

                                                             ii.     Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled).

                                                            iii.     Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place).

                                                            iv.     There is nothing inherently wrong with opposed piston or 2-stroke engines if done right.

d.      Electronics

                                                              i.     LRFs- unavailable

                                                             ii.     Thermals-unavailable

                                                            iii.     I^2- Gen 2 maximum

                                                            vi.     Texas cannot mass produce microprocessors or integrated circuits

                                                           vii.    Really early transistors only (e.g., transistor radio)

                                                          viii.    While it is known states exist with more advanced computer technology, the import of such systems are barred by the east coast states who do not approve of their use by militaristic entities.

 

Armor calculation appendix.

 

SHEET 1 Armor defeat calculator 4in-54 1200 yd

 

SHEET 2 Armor defeat calculator 4in-54 2000 yd

 

SHEET 3 Armor defeat calculator 6in HEAT

 

Range calculator

 

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7 hours ago, Dominus Dolorem said:

I was also wondering if it is necessary for the driver to have his own hatch?

 

I would recommend so, yes, hahaha.

 

7 hours ago, Dominus Dolorem said:

Is there a weight limit or minimum number of rounds required?


No for either but you have to remember that the Texas government would like to actually be able to use these things.

 

4 hours ago, Dominus Dolorem said:

I also forgot to ask, are there any width restrictions?


No, the Texas logistics system primarily operates on broad, open highways.

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48 minutes ago, Sturgeon said:

No for either but you have to remember that the Texas government would like to actually be able to use these things.

Would an 80-90 ton tank with 15 rounds for the main gun be acceptable to the military?

 

Quote

I would recommend so, yes, hahaha.

 

Our designers believe that they can achieve vastly superior frontal protection if this minor detail is neglected.

 

They claim that a floor mounted escape hatch would offer the driver better chances for the driver to get out alive in an emergency and thus believe that a drivers hatch would offer no real advantage.

 

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1 hour ago, Dominus Dolorem said:

Would an 80-90 ton tank with 15 rounds for the main gun be acceptable to the military?

 

 

Our designers believe that they can achieve vastly superior frontal protection if this minor detail is neglected.

 

They claim that a floor mounted escape hatch would offer the driver better chances for the driver to get out alive in an emergency and thus believe that a drivers hatch would offer no real advantage.

 

 

Like NLM said, you are competing against other people, and the judges will weigh your submission holistically. You're welcome to take radical risks like that, but you have to consider whether the judges will see those compromises as worth it.

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1 minute ago, Toxn said:

@Sturgeon trying to gauge the biases of the rangers/patrol et al - rifled vs. smoothbore guns?


From my perspective, no bias. Tech level is "cusp" for smoothbores, so the ammunition types expected to initially ship with the tank favor rifled guns, but the immediate next generation favor smoothbores.

Just as a reference point, if you recall the 2239 competition, the Texans have better metallurgy and better technical acumen for guns specifically (they are heavily invested in small arms, autocannons, and artillery). So even though we're talking about a tank intended to compete directly with Norman, the gun may be a half generation more advanced (reference: L11 or U-5TS).

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4 hours ago, Lord_James said:

Where do you find the engine dimensions for the MB 838 or AVDS 1790? I can find total volume, but nothing specific. 


https://ia800203.us.archive.org/19/items/CollectionOfDocumentsDescribingMTU830870And880SeriesEngines/Collection of Documents describing MTU 830 870 and 880 series engines.pdf

In other news, alien space whale cometh:

memsenT.png

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10 hours ago, Sturgeon said:


From my perspective, no bias. Tech level is "cusp" for smoothbores, so the ammunition types expected to initially ship with the tank favor rifled guns, but the immediate next generation favor smoothbores.

Just as a reference point, if you recall the 2239 competition, the Texans have better metallurgy and better technical acumen for guns specifically (they are heavily invested in small arms, autocannons, and artillery). So even though we're talking about a tank intended to compete directly with Norman, the gun may be a half generation more advanced (reference: L11 or U-5TS).

Thanks. Another question: what's the maximum weight a loader is expected to routinely lift? I'm scoping out armament and this gives me a handle on cartridge/shell weights.

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2 hours ago, Toxn said:

Thanks. Another question: what's the maximum weight a loader is expected to routinely lift? I'm scoping out armament and this gives me a handle on cartridge/shell weights.

 

It's generally accepted that 25kg (about the weight of solid shell/shot alone for 120-122mm) is the limit. Intuitively, this is probably the most a fit adult male could repeatedly move in a complex arc quickly during a fight. Virtually every serious tank armed with something larger (which still fired solid steel shot) had some sort of load-assist, if not an autoloader.

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5 minutes ago, Dominus Dolorem said:

SU/ISU152, Stumtiger, Yagdtiger, ect. They are not quite tanks, but they were manually loaded.

 

Sturmtiger??? You mean the 380mm rocket-mortar-armed 760lb shell-firing thing that was loaded via five men and a crane? THAT Sturmtiger?

 

PaK 44 was not in a different class than M58, having a less powerful round and a comparable weight shell (28kg).

 

ISU-152 is the only actual exception, though not a tank as you point out. As the exception, it proves the rule, as it often required an extra loader to haul its ~50kg shells, and the Soviets never returned to that scheme, certainly not in a turreted tank.

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