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Backstory (skip if you don't like alternate history junk)

 

The year is 2239. It has been roughly 210 years since the world was engulfed in nuclear war. Following the war, the United States splintered into hundreds of small statelets. While much knowledge was retained in some form (mostly through books and other printed media), the loss of population and destruction of industrial capability set back society immensely.

 

Though the Pacific Northwest was less badly hit than other areas, the destruction of Seattle and Portland, coupled with the rupturing of the Cascadia Subduction Zone in 2043, caused society to regress to a mid-19th century technology level. However, in the early 2100s, the Cascade Republic formed, centered near Tacoma. The new nation grew rapidly, expanding to encompass most of Washington and Oregon by 2239. The Cascade Republic now extends from the Klamath River in the south to the Fraser River in the north, and from the Pacific roughly to central Idaho. Over time, the standard of living and industrial development improved (initially through salvaging of surviving equipment, by the late 2100s through new development); the population has grown to about 4.5 million (comparable to 1950 levels), and technology is at about a 1940 level. Automobiles are common, aircraft are less common, but not rare by any means. Computers are nonexistent aside from a few experimental devices; while scientists and engineers are aware of the principles behind microchips and other advanced electronics, the facilities to produce such components simply do not exist. Low rate production of early transistors recently restarted.

 

The current armored force of the Cascade Republic consists of three armored brigades. They are presently equipped with domestically produced light tanks, dating to the 2190s. Weighing roughly 12 tons and armed with a 40mm gun, they represented the apex of the Cascade Republic's industrial capabilities at the time. And when they were built, they were sufficient for duties such as pacifying survivalist enclaves in remote areas. However, since that time, the geopolitical situation has complicated significantly. There are two main opponents the Cascade Republic's military could expect to face in the near future.

 

The first is California. The state of California was hit particularly hard by the nuclear exchange. However, in 2160, several small polities in the southern part of the state near the ruins of Los Angeles unified. Adopting an ideology not unfamiliar to North Korea, the new state declared itself the successor to the legacy of California, and set about forcibly annexing the rest of the state. It took them less than 50 years to unite the rest of California, and spread into parts of Arizona and northern Mexico. While California's expansion stopped at the Klamath River for now, this is only due to poor supply lines and the desire to engage easier targets. (California's northward advanced did provide the final impetus for the last statelets in south Oregon to unify with the Cascade Republic voluntarily).

 

California is heavily industrialized, possessing significant air, naval, and armored capabilities. Their technology level is comparable to the Cascade Republic's, but their superior industrial capabilities and population mean that they can produce larger vehicles in greater quantity than other countries. Intelligence shows they have vehicles weighing up to 50 tons with 3 inches of armor, though most of their tanks are much lighter.

The expected frontlines for an engagement with the Californian military would be the coastal regions in southern Oregon. Advancing up the coastal roads would allow California to capture the most populated and industrialized regions of the Cascade Republic if they advanced far enough north. Fortunately, the terrain near the border is very difficult and favors the defender;

Klamath-River-2-credit-Matt-Baun_USFWS.j

(near the Californian border)


The other opponent is Deseret, a Mormon theocratic state centered in Utah, and encompassing much of Nevada, western Colorado, and southern Idaho. Recently, tension has arisen with the Cascade Republic over two main issues. The first is the poorly defined border in Eastern Oregon / Northern Nevada; the old state boundary is virtually meaningless, and though the area is sparsely populated, it does represent a significant land area, with grazing and water resources. The more recent flashpoint is the Cascade Republic's recent annexation of Arco and the area to the east. Deseret historically regarded Idaho as being within its sphere of influence, and maintained several puppet states in the area (the largest being centered in Idaho Falls). They regard the annexation of a signficant (in terms of land area, not population) portion of Idaho as a major intrusion into their rightful territory. That the Cascade Republic has repaired the rail line leading to the old Naval Reactors Facility, and set up a significant military base there only makes the situation worse.

 

Deseret's military is light and heavily focused on mobile operations. Though they are less heavily mechanized than the Cascade Republic's forces, operating mostly armored cars and cavalry, they still represent a significant threat  to supply and communication lines in the open terrain of eastern Oregon / southern Idaho.

trbigsouthernbuttedsc-0883jpg-efd6c10e61

(a butte in the disputed region of Idaho, near Arco)

 

Requirements

 

As the head of a design team in the Cascade Republic military, you have been requested to design a new tank according to one of two specifications (or both if you so desire):

 

  • Medium / Heavy Tank
    • Weight: No more than 45 tons
    • Width: No more than 10.8 feet (3.25 meters)
    • Upper glacis / frontal turret armor of at least 3 in (76mm) LoS thickness
    • Side armor at least 1in (25mm) thick (i.e. resistant to HMG fire)
    • Power/weight ratio of at least 10 hp / ton
    • No more than 6 crew members
    • Primary armament capable of utilizing both anti-armor and high explosive rounds
  • Light tank
    • Weight: No more than 25 tons
    • Width: No more than 10.8 feet
    • Upper glacis / frontal turret armor of at least 1 in thickness
    • Side armor of at least 3/8 in (10mm) thickness
    • Power/weight ratio of at least 12 hp / ton
    • No more than 6 crew members
    • Primary armament capable of utilizing both anti-armor and high explosive rounds

 

Other relevant information:

  • Any tank should be designed to operate against either of the Cascade Republic's likely opponents (California or Deseret)
  • The primary heavy machine gun is the M2, the primary medium machine gun is the M240. Use of one or both of these as coaxial and/or secondary armament is encouraged.
  • The secret archives of the Cascade Republic are available for your use. Sadly, there are no running prewar armored vehicles, the best are some rusted hulks that have long been stripped of usable equipment. (Lima Tank Plant ate a 500 kt ground burst)
  • Both HEAT and APFSDS rounds are in testing. APCR is the primary anti-armor round of the Cascade Republic.
  • Either diesel or gasoline engines are acceptable, the Cascade Republic is friendly with oil producing regions in Canada (OOC: Engines are at about a late 1940s/early 50s tech level)
  • The adaptability of the tank to other variants (such as SPAA, SPG, recovery vehicle, etc.) is preferred but not the primary metric that will be used to decide on a design.
  • Ease of maintenance in the field is highly important.
  • Any designs produced will be compared against the M4 Sherman and M3 Stuart (for medium/heavy and light tank), as these blueprints are readily available, and these tanks are well within the Cascade Republic's manufacturing capabilities.

 

 

 

 

 

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7 hours ago, LostCosmonaut said:

Backstory (skip if you don't like alternate history junk)

 

The year is 2239. It has been roughly 210 years since the world was engulfed in nuclear war. Following the war, the United States splintered into hundreds of small statelets. While much knowledge was retained in some form (mostly through books and other printed media), the loss of population and destruction of industrial capability set back society immensely.

 

Though the Pacific Northwest was less badly hit than other areas, the destruction of Seattle and Portland, coupled with the rupturing of the Cascadia Subduction Zone in 2043, caused society to regress to a mid-19th century technology level. However, in the early 2100s, the Cascade Republic formed, centered near Tacoma. The new nation grew rapidly, expanding to encompass most of Washington and Oregon by 2239. The Cascade Republic now extends from the Klamath River in the south to the Fraser River in the north, and from the Pacific roughly to central Idaho. Over time, the standard of living and industrial development improved (initially through salvaging of surviving equipment, by the late 2100s through new development); the population has grown to about 4.5 million (comparable to 1950 levels), and technology is at about a 1940 level. Automobiles are common, aircraft are less common, but not rare by any means. Computers are nonexistent aside from a few experimental devices; while scientists and engineers are aware of the principles behind microchips and other advanced electronics, the facilities to produce such components simply do not exist. Low rate production of early transistors recently restarted.

 

The current armored force of the Cascade Republic consists of three armored brigades. They are presently equipped with domestically produced light tanks, dating to the 2190s. Weighing roughly 12 tons and armed with a 40mm gun, they represented the apex of the Cascade Republic's industrial capabilities at the time. And when they were built, they were sufficient for duties such as pacifying survivalist enclaves in remote areas. However, since that time, the geopolitical situation has complicated significantly. There are two main opponents the Cascade Republic's military could expect to face in the near future.

 

The first is California. The state of California was hit particularly hard by the nuclear exchange. However, in 2160, several small polities in the southern part of the state near the ruins of Los Angeles unified. Adopting an ideology not unfamiliar to North Korea, the new state declared itself the successor to the legacy of California, and set about forcibly annexing the rest of the state. It took them less than 50 years to unite the rest of California, and spread into parts of Arizona and northern Mexico. While California's expansion stopped at the Klamath River for now, this is only due to poor supply lines and the desire to engage easier targets. (California's northward advanced did provide the final impetus for the last statelets in south Oregon to unify with the Cascade Republic voluntarily).

 

California is heavily industrialized, possessing significant air, naval, and armored capabilities. Their technology level is comparable to the Cascade Republic's, but their superior industrial capabilities and population mean that they can produce larger vehicles in greater quantity than other countries. Intelligence shows they have vehicles weighing up to 50 tons with 3 inches of armor, though most of their tanks are much lighter.

The expected frontlines for an engagement with the Californian military would be the coastal regions in southern Oregon. Advancing up the coastal roads would allow California to capture the most populated and industrialized regions of the Cascade Republic if they advanced far enough north. Fortunately, the terrain near the border is very difficult and favors the defender;

Klamath-River-2-credit-Matt-Baun_USFWS.j

(near the Californian border)


The other opponent is Deseret, a Mormon theocratic state centered in Utah, and encompassing much of Nevada, western Colorado, and southern Idaho. Recently, tension has arisen with the Cascade Republic over two main issues. The first is the poorly defined border in Eastern Oregon / Northern Nevada; the old state boundary is virtually meaningless, and though the area is sparsely populated, it does represent a significant land area, with grazing and water resources. The more recent flashpoint is the Cascade Republic's recent annexation of Arco and the area to the east. Deseret historically regarded Idaho as being within its sphere of influence, and maintained several puppet states in the area (the largest being centered in Idaho Falls). They regard the annexation of a signficant (in terms of land area, not population) portion of Idaho as a major intrusion into their rightful territory. That the Cascade Republic has repaired the rail line leading to the old Naval Reactors Facility, and set up a significant military base there only makes the situation worse.

 

Deseret's military is light and heavily focused on mobile operations. Though they are less heavily mechanized than the Cascade Republic's forces, operating mostly armored cars and cavalry, they still represent a significant threat  to supply and communication lines in the open terrain of eastern Oregon / southern Idaho.

trbigsouthernbuttedsc-0883jpg-efd6c10e61

(a butte in the disputed region of Idaho, near Arco)

 

Requirements

 

As the head of a design team in the Cascade Republic military, you have been requested to design a new tank according to one of two specifications (or both if you so desire):

 

  • Medium / Heavy Tank
    • Weight: No more than 45 tons
    • Width: No more than 10.8 feet (3.25 meters)
    • Upper glacis / frontal turret armor of at least 3 in (76mm) LoS thickness
    • Side armor at least 1in (25mm) thick (i.e. resistant to HMG fire)
    • Power/weight ratio of at least 10 hp / ton
    • No more than 6 crew members
    • Primary armament capable of utilizing both anti-armor and high explosive rounds
  • Light tank
    • Weight: No more than 25 tons
    • Width: No more than 10.8 feet
    • Upper glacis / frontal turret armor of at least 1 in thickness
    • Side armor of at least 3/8 in (10mm) thickness
    • Power/weight ratio of at least 12 hp / ton
    • No more than 6 crew members
    • Primary armament capable of utilizing both anti-armor and high explosive rounds

 

Other relevant information:

  • Any tank should be designed to operate against either of the Cascade Republic's likely opponents (California or Deseret)
  • The primary heavy machine gun is the M2, the primary medium machine gun is the M240. Use of one or both of these as coaxial and/or secondary armament is encouraged.
  • The secret archives of the Cascade Republic are available for your use. Sadly, there are no running prewar armored vehicles, the best are some rusted hulks that have long been stripped of usable equipment. (Lima Tank Plant ate a 500 kt ground burst)
  • Both HEAT and APFSDS rounds are in testing. APCR is the primary anti-armor round of the Cascade Republic.
  • Either diesel or gasoline engines are acceptable, the Cascade Republic is friendly with oil producing regions in Canada (OOC: Engines are at about a late 1940s/early 50s tech level)
  • The adaptability of the tank to other variants (such as SPAA, SPG, recovery vehicle, etc.) is preferred but not the primary metric that will be used to decide on a design.
  • Ease of maintenance in the field is highly important.
  • Any designs produced will be compared against the M4 Sherman and M3 Stuart (for medium/heavy and light tank), as these blueprints are readily available, and these tanks are well within the Cascade Republic's manufacturing capabilities.

 

 

 

 

 

Could I ask for some extra information?

 

1. What is the name/designation of the previous tank? This is just so that my naming/numbering scheme is good in-universe.

 

2. What are the most common threats on the California/Deseret side? This breaks down into infantry anti-tank weapons, anti-tank guns and tank guns. Here I'm guessing something like the following, but you must please correct me:

  • California: bazooka analogues (~75mm penetration), 75-85mm anti-tank guns (~135mm penetration), 35-60mm light tank guns (50-75mm penetration), 75-85mm medium tank guns (~135mm penetration).
  • Deseret: bazooka analogues (~75mm penetration), 50-60mm anti-tank guns (50-75mm penetration), 35-60mm guns (50-75mm penetration) for heavier armoured cars, 20-40mm guns (25-50mm penetration) for lighter armoured cars.
  • Both: anti-tank rifles in the 12-15mm range (~25mm penetration), other primitive hollow charge weapons in the 50-80mm range (~75mm penetration).

 

3. What are the expected threats in the near future, at least according to Cascade's best intel? I'm guessing that the hardest-hitting weapons are moving to the 150-200mm penetration range, but that most weapons will move up to the 100-150mm penetration range. Again, you must correct me here.

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16 hours ago, Toxn said:

Could I ask for some extra information?

 

1. What is the name/designation of the previous tank? This is just so that my naming/numbering scheme is good in-universe.

 

2. What are the most common threats on the California/Deseret side? This breaks down into infantry anti-tank weapons, anti-tank guns and tank guns. Here I'm guessing something like the following, but you must please correct me:

  • California: bazooka analogues (~75mm penetration), 75-85mm anti-tank guns (~135mm penetration), 35-60mm light tank guns (50-75mm penetration), 75-85mm medium tank guns (~135mm penetration).
  • Deseret: bazooka analogues (~75mm penetration), 50-60mm anti-tank guns (50-75mm penetration), 35-60mm guns (50-75mm penetration) for heavier armoured cars, 20-40mm guns (25-50mm penetration) for lighter armoured cars.
  • Both: anti-tank rifles in the 12-15mm range (~25mm penetration), other primitive hollow charge weapons in the 50-80mm range (~75mm penetration).

 

3. What are the expected threats in the near future, at least according to Cascade's best intel? I'm guessing that the hardest-hitting weapons are moving to the 150-200mm penetration range, but that most weapons will move up to the 100-150mm penetration range. Again, you must correct me here.

 

1. The previous tank was the Light Tank M6, plus various unofficial nicknames.

 

2. Time for bullet points

 

  • California
    • In service
      • Heavy tank / heavy towed anti-tank gun: 89mm (3.5 in) gun with ~140mm RHA pen at 100 meters, ~80mm using HEAT
        • Much less common than medium / light guns
      • Medium tank / medium towed anti-tank gun: 70mm (2.75 in) gun with ~100mm pen at 100 meters, ~55mm using HEAT
      • Light tank / light towed anti-tank gun: 51mm (2 in) gun with ~75mm pen at 100 meters
      • Anti-tank rocket: 70mm diameter warhead, ~90mm penetration, effective range ~200 meters
        • Common infantry anti-tank weapons
    • In development
      • Improved 89mm gun with ~160mm pen (likely to be used on next generation Californian heavy tanks in early development)
      • Very heavy towed 108mm (4.25 in) gun with ~215mm pen at 100 meters (also to be used for indirect fire)
      • Improved 70mm gun with ~125mm penetration (expected to be used on next generation Californian tanks in early development)
      • Improved HEAT warheads with penetration up to 1.5 diameters when fired from existing rifled guns
      • Improved 70mm anti-tank rocket with ~110mm penetration
  • Deseret
    • In service
      • Heavy armored car armament: 57mm (2.25 in) gun with ~75mm pen at 100 meters
      • Medium armored car armament: 30mm autocannon with ~55mm pen at 100 meters
        • Most common vehicle armament, also used by Deseret's small force of light tanks
      • Anti-tank rocket: 76mm (3 in) rocket with ~60mm armor penetration (HEAT), effective range 400 meters
        • Most common infantry / cavalry antitank weapon, also limited use as vehicle mounted weapon
      • Medium 90mm recoilless rifle with ~75mm penetration
        • Towed, also vehicle mounted
      • Anti-tank rifle: 20mm single shot rifle with ~40mm penetration at 100 meters
        • Being phased out in favor of anti-tank rockets, retained for use against lightly armored targets
    • In development
      • Lightweight 76mm gun with ~90 mm penetration, for use as mobile artillery, heavy armored cars, and next generation light tanks
      • Improved antitank rocket with ~90mm penetration, coupled with longer range and shorter flight time
      • Heavy 120mm recoilless rifle with ~155mm penetration (HEAT)
        • Both towed / vehicle mounted (multiple to be mounted on wheeled anti-tank platform in development)
  • Common to both nations
    • Heavy machine gun with ~25mm penetration (it's an M2)
    • Various other weapons with limited / situational anti-tank capability (mortars, fragmentation/high explosive grenades, incendiary devices)
    • Mines
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4 hours ago, LostCosmonaut said:

 

1. The previous tank was the Light Tank M6, plus various unofficial nicknames.

 

2. Time for bullet points

 

  • California
    • In service
      • Heavy tank / heavy towed anti-tank gun: 89mm (3.5 in) gun with ~140mm RHA pen at 100 meters, ~80mm using HEAT
        • Much less common than medium / light guns
      • Medium tank / medium towed anti-tank gun: 70mm (2.75 in) gun with ~100mm pen at 100 meters, ~55mm using HEAT
      • Light tank / light towed anti-tank gun: 51mm (2 in) gun with ~75mm pen at 100 meters
      • Anti-tank rocket: 70mm diameter warhead, ~90mm penetration, effective range ~200 meters
        • Common infantry anti-tank weapons
    • In development
      • Improved 89mm gun with ~160mm pen (likely to be used on next generation Californian heavy tanks in early development)
      • Very heavy towed 108mm (4.25 in) gun with ~215mm pen at 100 meters (also to be used for indirect fire)
      • Improved 70mm gun with ~125mm penetration (expected to be used on next generation Californian tanks in early development)
      • Improved HEAT warheads with penetration up to 1.5 diameters when fired from existing rifled guns
      • Improved 70mm anti-tank rocket with ~110mm penetration
  • Deseret
    • In service
      • Heavy armored car armament: 57mm (2.25 in) gun with ~75mm pen at 100 meters
      • Medium armored car armament: 30mm autocannon with ~55mm pen at 100 meters
        • Most common vehicle armament, also used by Deseret's small force of light tanks
      • Anti-tank rocket: 76mm (3 in) rocket with ~60mm armor penetration (HEAT), effective range 400 meters
        • Most common infantry / cavalry antitank weapon, also limited use as vehicle mounted weapon
      • Medium 90mm recoilless rifle with ~75mm penetration
        • Towed, also vehicle mounted
      • Anti-tank rifle: 20mm single shot rifle with ~40mm penetration at 100 meters
        • Being phased out in favor of anti-tank rockets, retained for use against lightly armored targets
    • In development
      • Lightweight 76mm gun with ~90 mm penetration, for use as mobile artillery, heavy armored cars, and next generation light tanks
      • Improved antitank rocket with ~90mm penetration, coupled with longer range and shorter flight time
      • Heavy 120mm recoilless rifle with ~155mm penetration (HEAT)
        • Both towed / vehicle mounted (multiple to be mounted on wheeled anti-tank platform in development)
  • Common to both nations
    • Heavy machine gun with ~25mm penetration (it's an M2)
    • Various other weapons with limited / situational anti-tank capability (mortars, fragmentation/high explosive grenades, incendiary devices)
    • Mines

Thanks, updating my design.

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Primary entry, SPG and SPAAG to follow:

 

XM8 “Elk”

 

mhjYK82.jpg

 

Length: 6.6m (hull), 8.6m (total)

Width: 2.65m (hull), 3.25m (total)

Height: 2.7m

Weight: 41/22 t (combat weight)

Crew: 4 (commander, gunner, loader, driver)

 

Armour:

  • 100/25mm (upper hull front)
  • 100/25mm (lower hull front)
  • 65/25mm (hull side forward)
  • 25/15mm (hull side rear)
  • 25/15mm (hull rear)
  • 25/15mm (hull roof)
  • 25/15mm (hull floor)
  • 100/25mm (turret front)
  • 100/15mm (turret side forward)
  • 65/15mm (turret side rear)
  • 25/15mm (turret rear)
  • 100/25mm (mantlet)
  • 25/15mm (turret roof)

 

Weapons:

  • 80mm L/45 cannon:

               - APHE: 7.1kg, 820m/s, ~130mm RHA penetration (90’, 500m)

               - APCR: 4.3kg, 1045m/s, ~160mm RHA penetration (90’, 500m)

               - HEAT: 4.8kg, 500m/s, ~90mm RHA penetration (90’, any range)

               - HE: 6.1 kg, 500m/s

  • Browning M2 heavy machine gun (turret roof)
  • M240 machine gun (coaxial)

 

Engine: 18L, 450 HP (340 kW) V8 petrol engine (Ford GAA derivative)

Power/weight: 11.3 kW/t or 21.4 kW/t

Max speed (road): 45km/h or 60km/h

Max sustained speed (offroad): 30km/h or 40km/h

Range: 300km/550km

 

XOc9Y47.jpg

frRRUDt.jpg

 

Description

 

The M8 “Elk” was the result of a proactive design process intended to provide a ‘universal’ tank optimised for fighting a defensive war against Californian forces and serving in a more mobile role in the Oregon/Idaho sector. The design is also intended to have reserve capacity for upgrades as they become available.

The core of the vehicle is a simple hull with a clean, sloped front and a large engine bay in the rear separated from the crew compartment by a 25mm or 15mm (depending on the version) armoured bulkhead. The armour layout emphasises frontal engagements and crew protection, with the forward side armour (covering the crew compartment) being significantly thicker then the rear side armour.

 

The M8 is offered in two variants: a 40t ‘medium’ version and a 20t ‘light’ version. The medium version is designed to resist current-generation heavy anti-tank weapons across the hull front and turret frontal arc from any distance, with current generation medium anti-tank weapons being resisted across a 45 degree arc covering the crew compartment. The medium is expected to remain well protected against medium anti-tank weapons for the foreseeable future, and is expected to resist heavy anti-tank weapons across the hull front and turret front at ranges beyond 1000m. The light version sacrifices nearly all of its armour in favour of lower weight, retaining only 25mm plate to cover the frontal arc and crew compartment. This is, however, expected to provide protection against 20 and 30mm Deseret weapons at combat ranges. Some of this lightening is achieved through the use of aluminium components (most notably the road wheels) where possible. Although much less well protected than its medium cousin, the light version gains very good cross-country mobility and greater range. It also retains the excellent 80mm gun used by the medium, which is expected to remain effective against light and medium vehicles for the foreseeable future. The hull and turret are both of welded constuction, with castings only being used for a few components (most notably the gun mount and mantlet).

 

The engine bay is designed to facilitate service and repair, and has large rear doors for access to the engine and transmission. The engine and transmission, in turn, are mounted using a rail system so that they can be easily pulled. The radiators and fans are mounted in hinged doors on the hull roof, which also double as access points for service. The emphasis on ease of maintenance continues to the suspension system, which is a widened derivative of the historical HVSS designs used on the pre-war Sherman series of tanks. Each suspension unit mounts to hardpoints which protrude a bit below the hull proper, resulting in a very respectable 50cm of ground clearance. Due to the forward-heavy nature of the tank, the suspension units on the medium model are not evenly spaced. Instead the middle unit is positioned somewhat closer to the front unit than the rear unit. The engine, a 450-500 HP design based on the pre-war Ford GAA, drives vehicle through a rear sprocket. The medium and light versions use different transmission designs; with the medium’s being a more robust mechanical unit with a lower gear ratio, while the light uses a hydromatic unit based on that of the M24. Both vehicles are equipped with multiple reverse gears to facilitate shoot-and-reposition tactics.

 

The turret is roomy thanks to a large 1.8m turret ring, which is also expected to facilitate upgrade programs going forwards. It’s shape is six-sided, somewhat sloped, and contains generously-sized hatches for the crew. The turret is equipped with a full basket. The commander’s hatch is equipped with multiple vision blocks to provide good visibility while buttoned up. The commander and gunner also have access to periscopes (based on the M10 design) for the purposes of target acquisition and rough lay-in. The gunner’s periscope is selectable for 3X and 6X magnification, and has various reticles for the main ammunition types. A telescopic sight, based on the M70-series sights, is provided for fine lay-in. An azimuth indicator and gunner’s quadrant is provided for ranged fire missions. The rear of the turret houses the radio set – a new transistor design based on the pre-war SCR-500 series. This set includes an intercom system, and is expected to be less maintenance-intensive than our existing sets. The rear side sponson contains a small telephone, linked to the intercom system, to allow infantry to communicate with the crew.

 

The 80mm main gun has merely average elevation and depression: +20 to -9 degrees. This is something of a flaw, and may need to be corrected on future models of the vehicle. The turret drive is electric, and manages a full rotation in around 15 seconds. The electric unit does not allow for very precise movement of the turret at present, so the gunner’s handwheel is necessary for fine adjustment. In terms of power, the main gun is able to penetrate any commonly-encountered armoured vehicle from the front at combat ranges using the present APHE and APCR shells. It is expected to remain viable against most light and medium vehicles for the foreseeable future. The gun also sports a very good HE shell, which is fired using a low-velocity charge. The coaxial M240 machine gun provides a reliable level of firepower for anti-infantry work, while the roof-mounted M2 heavy machine gun provides a useful level of auxiliary firepower against soft-skinned vehicles, as well as a rudimentary anti-aircraft capability.

 

Overall the M8 offers good firepower, good protection (in the medium variant, at least) and decent mobility. It also offers a platform with significant margin for further development.

 

Acknowledgements

  • Jeeps (the Sherman site is freaking goldmine)
  • Various Sketchup users (especially Sketchy@Best, Stefan F., M L. and zdanwoj)
  • Whoever came up with that Tank Designer spreadsheet that Sturgeon posted

 

WxA75nk.jpg

C6u5cGW.jpg

Edit: I'm going to ask the Judges to use their imagination in regard to towing eyelets and radio aerials. Because I completely forgot to put those in.

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We now have our three judges, @Jeeps_Guns_Tanks, @LoooSeR, and @Zyklon.

 

We're really winging it this time, but here are the "rules" (more like guidelines) for contests:

 

On 4/29/2016 at 11:32 PM, Sturgeon said:

However, there are some ground rules. They are:

1. The contest must be a design contest of one kind or another. Just about any subject is fair game, such as armored fighting vehicles, fighter jets, cargo aircraft, small arms, electronics, radars, whatever.

2. There are four different kinds of participants. The first is the Solicitor. He creates the requirements for the contest that the Contestants must fulfill, and he also selects the three Judges for the contest. Solicitors may apply to me (the Admin) to create a contest, which I may approve if I like it. He then sets requirements to his liking (and individual requirements may be mutually exclusive with others), and the Judges evaluate the submissions created by the Contestants according to criteria outlined below.  The fourth type is the Sponsor, who provides the cash prize.

3. Submissions must include a graphic of some kind that incorporates some form of art or engineering. Examples that I consider to be acceptable are: A. A piece of original shaded and colored art showing the vehicle, B. A 3D drawing in Google Sketchup, C. A 3- or 4-view drawing in AutoCAD or scanned from drafting paper, D. A render of a solid model in Solidworks. Anything roughly equivalent to this level of effort is acceptable. What I would not consider to be acceptable would be: a. A Pimp-My-Gun "render", b. an MS Paint photomanip, c. a drawing in a sketchbook, etc. It's true that any one of these mediums could be used in a highly creative way, but the examples shown here do not really reflect the minimum level of effort we're looking for. I highly encourage judges to dismiss (i.e. not judge) submissions that do not meet this criteria.

4. Judges should further evaluate submissions based on their technical merit, conceptual creativity and cleverness, and the maturity of the overall concept. Often, contests will include requirements that cannot all be met except through pseudoscientific wankery (which should count against a submission, unless the contest calls for it explicitly), so Judges should consider submissions according to their own concept, so long as it at least attempts to meet some of the original requirements.

5. While the Solicitor selects the three Judges, he himself cannot be one. Further, the Judges selected may be vetoed by the Admin (me). The Solicitor may select more or less than three Judges, with Admin approval.

6. The Solicitor and the three Judges may submit their own designs to the contest, but they cannot take any place or win any money. The Sponsor may also submit a design, and may place and win (his own) prizes.

7. The top prize should be approximately $50 cash or equivalent. Prizes should be monetary only.

 

8. Sponsors are not selected, they must volunteer. Sponsors may also be the Solicitor, but they then follow Solicitor rules for submitting designs. Likewise for Sponsors also being Judges.

That should be about it, folks!

 

Basically, we still need our Sponsor, but that's detail shit IMO.

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Very long-time lurker, this competition finally got me to register.

I have an idea which will be ironed out and hopefully posted within a week.

Two question though-

1. other than the M2 and M240, are there any other Cascade standard-issue items to consider? Fuels (80 octane gasoline? 40 cetane diesel? Personal equipment?)

2. What is the industrial base capable of steel-wise? (Thicknesses rolled, weights cast, guns forged)

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47 minutes ago, N-L-M said:

Very long-time lurker, this competition finally got me to register.

I have an idea which will be ironed out and hopefully posted within a week.

Two question though-

1. other than the M2 and M240, are there any other Cascade standard-issue items to consider? Fuels (80 octane gasoline? 40 cetane diesel? Personal equipment?)

2. What is the industrial base capable of steel-wise? (Thicknesses rolled, weights cast, guns forged)

 

Thanks for joining, and welcome to the forums! In response to your questions, and a few I've been asked by other people;

 

  • The standard grade of gasoline is 87 octane (Some prewar refining capacity survived, and kept making fuel for prewar automobiles. Even though there's new-build refineries now they've decided to stick with 87). Most diesel is actually biodiesel, so the cetane ratings are a bit higher than expected.
  • The current gun calibers in service are 20mm, 40mm, 55mm, 80mm, 95mm, and 120mm. However, since we're assuming a new gun is going to be developed, don't limit yourself to just those calibers.
  • Things that aren't available at the current technology base: computerized FCS, ATGMs (electronics just aren't advanced enough for anything except maybe an X-7 clone).
  • Manufacturing capabilities:
    • The Cascade Republic's ability to cast steel is pretty good; test castings up to ~35 tons and the size of a medium tank hull have been done. Likewise, RHA up to about 6 inches thickness is readily produced. A big limitation is stamping; something like the stamped T-34 turret isn't readily producible (though the cast version is).
    • Plastics are at about early 1950s technology; notably aramids like kevlar and nomex aren't in production (though they are known obviously).
    • Tungsten is available (there are mines in Canada, controlled by friendly nations). DU is not (what can be salvaged from prewar isn't enough for any real use, and gotta have EU to make DU).
  • Any publicly available research from prewar (OOC: now) can be used. If you want to crack open Technology of Tanks and distill it into a CAD model, feel free.

 

Let me know if you/anyone else has questions. Also, a big thank you to Loooser, Jeeps, and Zyklon for judging.

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1 hour ago, Sturgeon said:

We now have our three judges, @Jeeps_Guns_Tanks, @LoooSeR, and @Zyklon.

 

We're really winging it this time, but here are the "rules" (more like guidelines) for contests:

 

 

Basically, we still need our Sponsor, but that's detail shit IMO.

We also need a time frame for a competition. 

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4 hours ago, N-L-M said:

Very long-time lurker, this competition finally got me to register.

I have an idea which will be ironed out and hopefully posted within a week.

Two question though-

1. other than the M2 and M240, are there any other Cascade standard-issue items to consider? Fuels (80 octane gasoline? 40 cetane diesel? Personal equipment?)

2. What is the industrial base capable of steel-wise? (Thicknesses rolled, weights cast, guns forged)

 

Awesome, welcome aboard!

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6 hours ago, Toxn said:

Primary entry, SPG and SPAAG to follow:

 

M8 “Elk”

 

mhjYK82.jpg

 

Length: 6.6m (hull), 8.6m (total)

Width: 2.65m (hull), 3.25m (total)

Height: 2.7m

Weight: 45/25 t (empty weight)

Crew: 4 (commander, gunner, loader, driver)

 

Armour:

  • 100/25mm (upper hull front)
  • 100/25mm (lower hull front)
  • 65/25mm (hull side forward)
  • 25/15mm (hull side rear)
  • 25/15mm (hull rear)
  • 25/15mm (hull roof)
  • 25/15mm (hull floor)
  • 100/25mm (turret front)
  • 100/15mm (turret side forward)
  • 65/15mm (turret side rear)
  • 65/15mm (turret rear)
  • 65/15mm (mantlet)
  • 25/15mm (turret roof)

 

Weapons:

  • 80mm L/45 cannon:

               - APHE: 7.1kg, 820m/s, 134mm RHA penetration (90’, 500m)

               - APCR: 4.3kg, 1045m/s, 162mm RHA penetration (90’, 500m)

               - HEAT: 4.8kg, 500m/s, 90mm RHA penetration (90’, any range)

               - HE: 6.1 kg, 500m/s

  • Browning M2 heavy machine gun (turret roof)
  • M240 machine gun (coaxial)

 

Engine: 18L, 450 HP (340 kW) V8 petrol engine (Ford GAA derivative)

Power/weight: 7.6 kW/t or 13.6 kW/t tonne

Max speed (road): 45km/h or 60km/h

Max sustained speed (offroad): 30km/h or 40km/h

Range: 300km/550km

 

XOc9Y47.jpg

frRRUDt.jpg

 

Description

 

The M8 “Elk” was the result of a proactive design process intended to provide a ‘universal’ tank optimised for fighting a defensive war against Californian forces and serving in a more mobile role in the Oregon/Idaho sector. The design is also intended to have reserve capacity for upgrades as they become available.

The core of the vehicle is a simple hull with a clean, sloped front and a large engine bay in the rear separated from the crew compartment by a 25mm or 15mm (depending on the version) armoured bulkhead. The armour layout emphasises frontal engagements and crew protection, with the forward side armour (covering the crew compartment) being significantly thicker then the rear side armour.

 

The M8 is offered in two variants: a 45t ‘medium’ version and a 25t ‘light’ version. The medium version is designed to resist current-generation heavy anti-tank weapons across the hull front and turret frontal arc from any distance, with current generation medium anti-tank weapons being resisted across a 45 degree arc covering the crew compartment. The medium is expected to remain well protected against medium anti-tank weapons for the foreseeable future, and is expected to resist heavy anti-tank weapons across the hull front and turret front at ranges beyond 1000m. The light version sacrifices nearly all of its armour in favour of lower weight, retaining only 25mm plate to cover the frontal arc and crew compartment. This is, however, expected to provide protection against 20 and 30mm Deseret weapons at combat ranges. Some of this lightening is achieved through the use of aluminium components (most notably the road wheels) where possible. Although much less well protected than its medium cousin, the light version gains very good cross-country mobility and greater range. It also retains the excellent 80mm gun used by the medium, which is expected to remain effective against light and medium vehicles for the foreseeable future.

 

The engine bay is designed to facilitate service and repair, and has large rear doors for access to the engine and transmission. The engine and transmission, in turn, are mounted using a rail system so that they can be easily pulled. The radiators and fans are mounted in hinged doors on the hull roof, which also double as access points for service. The emphasis on ease of maintenance continues to the suspension system, which is a widened derivative of the historical HVSS designs used on the pre-war Sherman series of tanks. Each suspension unit mounts to hardpoints which protrude a bit below the hull proper, resulting in a very respectable 50cm of ground clearance. Due to the forward-heavy nature of the tank, the suspension units on the medium model are not evenly spaced. Instead the middle unit is positioned somewhat closer to the front unit than the rear unit. The engine, a 450-500 HP design based on the pre-war Ford GAA, drives vehicle through a rear sprocket. The medium and light versions use different transmission designs; with the medium’s being a more robust mechanical unit with a lower gear ratio, while the light uses a hydromatic unit based on that of the M24. Both vehicles are equipped with multiple reverse gears to facilitate shoot-and-reposition tactics.

 

The turret is roomy thanks to a large 1.8m turret ring, which is also expected to facilitate upgrade programs going forwards. It’s shape is six-sided, somewhat sloped, and contains generously-sized hatches for the crew. The turret is equipped with a full basket. The commander’s hatch is equipped with multiple vision blocks to provide good visibility while buttoned up. The commander and gunner also have access to periscopes (based on the M10 design) for the purposes of target acquisition and rough lay-in. The gunner’s periscope is selectable for 3X and 6X magnification, and has various reticles for the main ammunition types. A telescopic sight, based on the M70-series sights, is provided for fine lay-in. An azimuth indicator and gunner’s quadrant is provided for ranged fire missions. The rear of the turret houses the radio set – a new transistor design based on the pre-war SCR-500 series. This set includes an intercom system, and is expected to be less maintenance-intensive than our existing sets. The rear side sponson contains a small telephone, linked to the intercom system, to allow infantry to communicate with the crew.

 

The 80mm main gun has merely average elevation and depression: +37 to -8 degrees. This is something of a flaw, and may need to be corrected on future models of the vehicle. The turret drive is electric, and manages a full rotation in around 15 seconds. The electric unit does not allow for very precise movement of the turret at present, so the gunner’s handwheel is necessary for fine adjustment. In terms of power, the main gun is able to penetrate any commonly-encountered armoured vehicle from the front at combat ranges using the present APHE and APCR shells. It is expected to remain viable against most light and medium vehicles for the foreseeable future. The gun also sports a very good HE shell, which is fired using a low-velocity charge. The coaxial M240 machine gun provides a reliable level of firepower for anti-infantry work, while the roof-mounted M2 heavy machine gun provides a useful level of auxiliary firepower against soft-skinned vehicles, as well as a rudimentary anti-aircraft capability.

 

Overall the M8 offers good firepower, good protection (in the medium variant, at least) and decent mobility. It also offers a platform with significant margin for further development.

 

Acknowledgements

  • Jeeps (the Sherman site is freaking goldmine)
  • Various Sketchup users (especially Stefan F., M L. and zdanwoj)
  • Whoever came up with that Tank Designer spreadsheet that Sturgeon posted

 

WxA75nk.jpg

C6u5cGW.jpg

 

What program did you use to make the model, and did it just have an HVSS suspension in it already?

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@LostCosmonaut and I discussed some additional specifics for Cascade:

 

Global trade, especially across the Pacific

Rubber not an issue, may want steel alternative parts

Aircraft industry capable of making advanced piston engined aircraft, early turbines

Cacade Republic does have a domestic source of aluminum

None of the countries currently has nuclear capability

Gun metallurgy late '40s equivalent - could not make Rheinmetall 120 even for testing

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13 minutes ago, Sturgeon said:

@LostCosmonaut and I discussed some additional specifics for Cascade:

 

Global trade, especially across the Pacific

Rubber not an issue, may want steel alternative parts

Aircraft industry capable of making advanced piston engined aircraft, early turbines

Cacade Republic does have a domestic source of aluminum

None of the countries currently has nuclear capability

Gun metallurgy late '40s equivalent - could not make Rheinmetall 120 even for testing

My understanding is that, in a post-apocalyptic world, aluminium will actually remain one of the most commonly used metals for a long time due to post-urban mining and recasting.

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      1.     List vehicle features which improve its fightability and useability.
      Additonal Features:
      Feel free to list more features as you see fit, in more categories.
      Free expression zone: Let out a big yeehaw to impress the world with your design swagger! Kindly spoiler this section if it’s very long.
       
       Example for filling in Appendix 1
       Example for filling in Appendix 2
       Example for filling in Appendix 3

      GOOD LUCK!
    • By Sturgeon
      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.
       

       
      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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