Competition: Tank Design 2239

[A. T. Mahan]

120MM GUN TANK T44

Renton Shipbuilding and Locomotive Works

A Pacific Car and Foundry Company

 

The 120mm Gun Tank T44, designed primarily by the Renton Shipbuilding and Locomotive division of Pacific Car and Foundry, is a fully-tracked armored fighting vehicle armed with a 120mm smoothbore gun. Research and exploratory investigation determined that there were a number of designs and concepts with great potential to leverage and improve the combat effect of the vehicle. The most promising hull that PACAR-RSL located was the M47 Patton -- the combination of castings and weldments of high-quality steel was well within the production capabilities of our facility, and the vehicle weight of 90000lbs would be able to be reduced sufficiently to meet the required weight limit. Noting that the vehicle weight specified in the contract (90,000lb) does not specify whether it is the unloaded or loaded weight, the Program Manager determined that it specified the unloaded weight. In any event, PACAR-RSL has several proposed variants (and has produced prototypes of them) that meet varying weight goals.

 

Structure:

The original M47’s structure is highly dated. While PACAR-RSL has substantial experience with high-quality castings of the scale required, and while PACAR produced M26 Pershing 90mm gun medium tanks in 1944 and 1945 (and retains sufficient quantities of the technical data package to resume production of mildly improved versions of those tanks if the Government would so desire), castings are not compatible with the composite armor techniques that PACAR and our subcontractors have developed based on combat-proven prewar efforts. As a shipbuilding concern, PACAR-RSL possesses substantial experience producing high-quality weldments of extremely high grade steels, and many of our welders are certified to weld armor steels. This trained and capable workforce allowed our design team to rework the monocoque (armor-as-structure) hull and turret of the M47 to suit both the HAP-1 derived armor package and to lighten the vehicle. This resulted in an allowable armor weight of nearly 10,000lb for the hull, sufficient to utilize the HAP-1 armor on a recontoured lower frontal hull.

The hull itself is constructed of welded 1.0” to 1.5” (+/- 0.05”) high strength steel plate,

The turret is of a completely new, all-welded design heavily inspired by the pre-war Abrams design, as far as general shape is concerned.

 

Protection:

 

Central to our design is the incorporation of highly advanced composite armors to reduce the threat of shaped-charge warheads. Pre-war literature indicated that these antitank munitions were most concerning for designers of the so-called first and second generation of main battle tanks, due to their light weight and relatively high penetrative ability, and Cascadian control of the only large supplies of depleted uranium and tungsten in the region result in a greatly reduced threat from long-rod fin-stabilized discarding sabot kinetic penetrators. In cooperation with the Pacific Aero Products Company of Seattle, we have spent considerable time and effort developing ceramic and other composite armor technologies, and believe that we have managed to develop an armor package similar in concept to the BRL-1 and HAP-1 armor packages used on various models of early model pre-war M1 Abrams tanks. Our testing has determined that the armor package we have chosen for the vehicle is substantially lighter and more protective than rolled homogeneous steel or cast steel armor, although it is bulkier and substantially more expensive. The armor utilizes combinations of three types of Non-Explosive Reactive Armor (NERA) packages, the Type I array of three thin parallel sandwiches of 5083-H32/elastomer/5083-H32 mounted on large pre-compressed coil springs, the Type II array of layered ceramic/5083-H32/elastomer/5083-H32 sandwich plates mounted at an angle such that an incoming projectile from within 15 degrees of horizontal must penetrate a minimum of four panels, and the Type IIIA/B composite array. We utilize two different composite arrays. The Type IIIA, used on the turret face, consists of a layer of ceramic tiles, a fiberglass-reinforced polymer backer, a layer of elastomer, a layer of depleted uranium, a fiberglass-reinforced polymer backer, a layer of high hardness armor steel, and the hull structure. The Type IIIB, used on the turret sides and lower glacis plate, is the same as that on the turret face, except the depleted uranium is replaced with high hardness steel. This reduces protection against kinetic energy penetrators, but greatly reduces weight, as high hardness steel is 60% lighter than depleted uranium, and the protection is still very good.

 

We have been particularly focused on Carborundum (Silicon Carbide) as the ceramic used in the armor, although experiments have determined that Boron Carbide offers more protection, but is substantially more difficult to manufacture and work with. While large quantities of B4C exist at the Hanford Site in the form of neutron dampers and shielding, and control rods, they would require substantial effort to form into a usable armor material and at this time the yield rate on B4C tiles of the appropriate size is low to the point of total impracticality - at best, we have determined that current technology will produce no more than 5% of a given batch of tiles that meets QA/QC. We have therefore determined that the most weight and efficient armor scheme would be to more-or-less duplicate the HAP-1 armor construction, substituting Silicon Carbide for Boron Carbide where appropriate, and utilizing the supplies of depleted uranium available at the Hanford Site (estimated to be 2,380 tons, appropriate for approximately 750 vehicles based on current projections of 6000lb of DU per vehicle) would provide substantial kinetic protection at the cost of increased weight.

Our armor concept, admittedly very heavily inspired by that of the early M1 Abrams designs, provides significant protection for its weight, especially considering the smaller protected volume and reduced level of protection chosen. The turret faces are intended to provide protection equivalent to 20-25 inches of rolled homogeneous steel, but are some 70% lighter.

We would note that the Cascadian Government should seek to acquire access to greater supplies of uranium for use in this and other defence programs, and note that research indicates four thousand tons of dry-cask stored spent nuclear fuel each in the former Illinois, former Pennsylvania, and former South Carolina regions and between 3,000 and 4,000 tons each in California, former Alabama, Florida, New York, and Georgia regions. While most of these areas are over a thousand miles away, if Cascadia can secure access to these supplies, they represent approximately 32,500 tons of highly enriched uranium, which would be invaluable for reprocessing into depleted uranium for tank armors, or Special Materials for use in other programs. PACAR-RSL has been making inquiries through traditional trade channels as to the feasibility of cross-country transportation of these materials, but government support would aid the endeavour greatly.

It is worth mentioning that this armor design package more-or-less requires the production of a gaseous-diffusion uranium enrichment cascade and the production of weapons-grade uranium. This could be expected to produce 16.9 tons of U-235, enough for over two thousand 25-kiloton nuclear devices.

Further protection comes from the incorporation of Contact and Rat, explosive reactive armours derived from the Soviet Kontakt-family tiles. Similar except for size and shape, these require no outside initiation, being a box with two steel plates sandwiching a piece of explosive. Contact is used primarily on the turret face, bow, hull, and turret sides, while Rat, derived from the curved tile of the pre-war US Army M19 ARAT tile, is used only on the hull and turret sides as an up-armor kit. Each Contact tile is 12” wide, 6” tall, and weighs 12.5lb. Each Rat tile weighs approximately 40lb, is 20” tall, 15” wide, and mounted on a hinged bracket that allows them to be angled vertical, or angled about 15 degrees down. This reduces the danger to supporting infantry posed by the tile’s detonation. The 238 Contact and 47 Rat tiles able to be mounted on the vehicle only add a maximum of 4,900lb including mounting hardware while providing greatly increased protection.

Contact explosive reactive armor tile (12"x6", 12.5lb)

Rat explosive reactive armor tile (15"x20", 40lb)

 

The armor layout is as follows:

• Turret

  • Turret face:

    • 0.75” HHS face armor, Type I array, Type II array, Type IIIA array, 1” RHA structure

      • 16" RHAe kinetic, 30" RHAe chemical

    • 14 tiles per side of Contact, 28 total

      • Contact tiles provide 14" RHAe against single-stage HEAT threats, ~4" RHAe against full-caliber kinetic threats. 

  • Turret side:

    • 0.75” HHS face, Type I array, Type II array, Type IIIB array, 0.75” RHA structure

      • 12" RHAe kinetic, 27" RHAe chemical

    • 11 tiles Contact and 7 RAT tiles per side, 22 Contact and 14 RAT tiles.

      • RAT tiles provide 18" RHAe against single stage HEAT warheads, 20" RHAe against full-caliber kinetic threats, and decrease the efficacy of subcaliber kinetic threats by 15%. This is due to the greater thickness of steel in the tile. 

  • Turret rear:

    • 2.25” HHS over 0.75” RHA

      • 3.5" RHAe

  • Turret roof:

    • 1.0” HHS

      • 1.2" RHAe

    • 28 Contact tiles

• Hull

  • Upper glacis plate:

    • 3” HHS plate sloped at 80 degrees from vertical (17” LOS)

      • 20" RHAe line of sight

    • 44 Contact tiles

  • Lower glacis plate:

    • 0.75” HHS plate, Type I array, Type II array, Type IIIB array, 1” HHS hull

      • 12.5" RHAe kinetic, 27.5" RHAe chemical

    • 5 tiles Rat

  • Hull Side:

    • 2.25” HHS over 0.75” RHA

      • 3.5" RHAe

    • Up-armor side-skirts consisting of a Type I array

      • 5" RHAe kinetic, 11" RHAe chemical

    • 70 tiles Contact per side plus 28 tiles of RAT

  • Hull rear: 2.0” RHA

  • Hull bottom: 0.75” HHS

    • 0.9" RHAe

  • Hull roof: 0.75” HHS

    • 0.9" RHAe

 

Firepower:

Other work with the Pacific Aero Products Company focused on the development of improved ammunition designs. PACAR-RSL leveraged PAPC’s advanced aerodynamic analytical techniques to aid in the development of improved fin-stabilized smoothbore ammunition. Research on prewar technologies demonstrated a number of programs conducted by the prewar US Army that incorporated smoothbore guns, and industrial analysis has determined that a maximum chamber-pressure of 55,000psi is within current capabilities, and based on research trends in metallurgy, a chamber pressure of 75,000psi should be achievable within five years, and 100,000psi in ten years. While this will result in a lengthened gun compared to prewar designs (The M256 120mm gun was only a 44-caliber gun), a 50-caliber 120mm gun with a tube weight of not more than 2,900lb and an all-up weight of not more than 4,400lb is entirely viable.

We have developed a gun, the 120mm Gun T123E7, that produces a muzzle energy of 4,300 ft-ton with a 50lb armor-piercing capped, ballistic capped projectile (MV = 3,500ft/sec, 50lb shot M358). We estimate that this will drive a 22lb Hanfordite (U-238) penetrator at approximately 4,500ft/sec, giving the capability to defeat greater than 25” of rolled homogenous steel at 2,000 yards, and greatly simplifying the design of the ballistic computer. It uses a vertically sliding breechblock reverse-engineered at great length from surviving examples of the Watervliet Arsenal-produced M256 120mm gun. While the current metallurgy and QA/QC is not sufficient to produce breech blocks capable of the 135,000psi of M256, we believe that with advances in electronically controlled machining, it is feasible. We are planning an exploratory expedition to the Watervleit Arsenal area to gain what prewar technical data we can, particularly on the M256 and M360 guns.

Gun, Smoothbore, 120mm T123E7 (120x570R, L/60)

T123E7 is a 60-caliber 120-mm smoothbore gun with a vertically sliding breechblock, hydropneumatic recoil mechanism, and chrome-lined bore. It has a fume extractor to reduce the rate of propellant gas ingress into the turret, and a thermal sleeve to stabilize the temperature along the bore and reduce bore irregularities due to thermal expansion. It fires 120x570mm fixed ammunition using a cellulose-fiber combustible cartridge case with a metal base cap, reducing the weight of the cartridge case by some 30lb compared to a brass case (107lb for brass case M358 APC-T vs ~55lb for T494 APFSDS-T). Decreased AP projectile weight due to the usage of armor-piercing fin-stabilized discarding sabot ammunition further reduces the weight of the armor-piercing projectile by nearly half, from 50lb to 26lb.

120mm XM442 Armor-Piercing Fin-Stabilized Discarding Sabot, Tracer (22lb Oralloy penetrator, 4,400ft/s MV)

 

Additional projectiles, such as HEP-FS-T, HE-FRAG-FS-T and HEAT-FS-T are under development, as are training projectiles.

120mm M358E1 APCBC-FS-T (50lb projectile, 3,500ft/s MV)

 

The gun and mount are electrically driven in train and elevation via a geared drive and proportionally controlled motors derived from a mixture of naval fire control equipment and aircraft gun turrets. This had an added benefit of easing the development of an analog two-axis gun stabilization system. The fire control system is electromechanical and analog-electronic, and consists of four components: the T92D gunner’s articulated periscope, the T19 automatic stereoscopic rangefinder, the electrical gun drive, and the T14 gun computer. The gun computer is a miniaturized transistorized electromechanical and analog-electronic computer that incorporates ambient temperature, range as measured from the stereoscopic rangefinder, and the average rate of traverse of the gun over the past one to three seconds to apply lead, cant and Coriolis correction, and superelevation, and align the gun to the sights. When the firing switch is depressed, a set of microswitches delays completion of the firing circuit until the sights are properly aligned, aiding in firing on the move or from a short halt. The gunner’s articulated periscope is a combination 1x-3x variable power unity sight and 3-20x magnified sight, with coated lenses, reticle illumination, and incorporating image intensifying night vision equipment. The image intensifying system is mounted at the end of the optical train, allowing the gunner to use the full magnification range even in reduced lighting conditions. The T19 rangefinder is mounted across the width of the turret and is a 108” base stereoscopic rangefinder equipped with an electro-optical automatic ranging mechanism.

 

Using the following equations, from Material Testing Procedure 3-2-702 (US Army Test and Evaluation Command, Common Engineering Test Procedure for Optical Rangefinders, 20 Apr. 1966, Aberdeen, Maryland), we calculate the T19 rangefinder has a mechanical accuracy of [x] meters. 

For a base length B of 2.769m, a range R1 of 2,000m
[math goes here]

 

The rangefinder can be used by the commander in the manual mode to either produce a more accurate ranging solution and in the event of automatic ranging mechanism failure. Both the commander and gunner can use the rangefinder, although as the fire control system is designed around and as-yet unproduced laser rangefinder, the primary control of automatic rangefinding is on the gunner's controls. The T14 gun computer can also accept manual input of range information via a dial, in 100-yard increments. The automatic mechanism is derived from Leika’s work in camera autofocus mechanisms, and is based on a small array of lead (II) sulfide photosensors similar to those used in early-model AIM-9 Sidewinder air-to-air missiles and a very simple electrical circuit. Early testing has determined that it can resolve ranges with a similar accuracy as a human operator in ⅓-½ the time, depending on the skill of the human operator. The turret and rangefinding system is also designed for-but-not-with a laser rangefinder, which would replace the optical rangefinder and improve gun depression from 12 degrees to 14 degrees. A laser rangefinder similar to the prewar AN/VVG-2 (Ruby, 694.3nm, 50mJ pulse, 125J maximum output) as used in the M60A3 would reduce the ranging time to 1.5 seconds and reduce the typical ranging error from several hundred yards to tens of yards. The ranging time is currently the largest component of the firing sequence, as the design of the T14 gun computer requires it to constantly update the firing solution for all inputs except range and lead, and lead correction is applied more-or-less instantaneously upon depression of the gunner's automatic ranging switch. 

• The T123E7 120mm smoothbore gun is provided with 56 rounds of ammunition in a blow-out protected bustle rack and twenty-four rounds in supplementary ammunition racks to either side of the loader, a total of 80 rounds.
• There is a 7.62mm M240 machine gun mounted coaxially to the main gun, with 8,000 rounds of 7.62x51mm (2,000 ready).
• There is a 7.62mm M240 machine gun provided for the loader mounted in a race-ring mount around his hatch with 2,000 rounds of 7.62x51mm (200 ready)
• There is a .50 M2 machine gun provided for the commander on a ring mount around the commander’s cupola with 2,000 rounds of .50 ammunition (100 ready)
• Provision is made for the storage of the crew’s individual weapons and field equipment, including four 5.56mm rifles and ammunition.

 

Mobility:

T44 uses a torsion-bar suspension, with six individually sprung road-wheels per track connected to double-acting bar-in-tube springs providing substantially improved suspension travel to the original single-acting suspension.

There are two powertrains currently proposed. The first, a prewar design Continental AVDS-1790-5B is a known quantity, an extremely reliable and widely used turbosupercharged diesel V-12 producing 810 horsepower at 2,400RPM. This, in combination with the CD-875-2 four-speed automatic transmission produces a maximum speed of 35 miles an hour on road, and the improved double-acting torsion bar suspension provides an increased rough-terrain speed of approximately 12 miles per hour, compared to nine miles an hour for the Medium Tank M4. This gives the vehicle a combat range of approximately 430 miles with 310 gallons of Diesel fuel.

The second powertrain is derived from prewar work on gas turbines. It is a simple, reliable gas turbine of 65” length and 25” diameter that, due to manufacturing limitations, only produces about 1,000 horsepower. Similar prewar designs produced approximately 1,500 horsepower in ground use and 1,800 horsepower in aviation use, but due to manufacturing limitations and for safety reasons, the turbine is limited to 1,200hp SHP emergency power for ten minutes, and 1,000 horsepower maximum. This drives a CD-1100-4F2 crossdrive automatic six-speed transmission (four forward, two reverse), resulting in a maximum road speed of 48 miles per hour and a rough-terrain speed of 22 miles per hour, although crew comfort is a significant concern and shock absorption is an issue at such speeds. This engine, with the associated APU, gives the vehicle a combat range of approximately 375 miles, although with greater speed than the AVDS-1790.

The strategic mobility of the T44 tank is provided by the vehicle’s high speed and substantial reliability. Rail transport of the T44 requires removing the side-skirts and side explosive reactive armor tiles, requiring one hour per vehicle plus a wrecker capable of lifting 1,300lb. Alternatively, the vehicle can be road-marched in combat condition. 

 

In summary, the T44 medium tank meets all of the required design specifications:

• It is 90,000lb unloaded, and 128,000lb at combat weight.

• The fenders fold up to ensure a 129” maximum width (otherwise 135” width)

• The upper frontal plate is 3” thick sloped at 80 degrees from vertical, giving an effective line of sight thickness of 17”

• The side armor is 3” thick

• The power to weight ratio is at worst 16hp/ton (loaded, 810hp engine) and at best 19.6hp/ton

• The tank has a crew of four: Driver, TC, gunner, and commander.

• The primary armament, 120mm gun T123E7, is capable of firing both antiarmor and high explosive projectiles.

• 9ft 8” tall

 

120mm Gun Tank T44 specifications:

• Empty weight: 94,000lb
• Operating empty weight: 109,250lb
• Combat weight: 128,000lb
• Height: 116"
• Width: 168.639 inches
• Length: 233.5" (hull), 415.5" overall, gun forward.
• Ground clearance: 21" at combat weight, less at OEW.
• Engine: Pseudo-Lycoming T53, 750lb/1,000shp
• APU: Two-stroke 25 horsepower Yamaha outboard powerhead
• Transmission: CD-1100-4F2. Four speeds forward, two reverse. Automatic crossdrive transmission. Engine and transmission are a powerpack. 
• Track: Modified T158 track, cut down to 23" wide. 
• Suspension: 74" long bar-in-tube double acting torsion bars, friction snubbers on the first two and last two pairs of road wheels each side (duals on the first road wheel), shock absorbers on the first, second, fifth, and sixth road wheels each side. Three return rollers each side. A total of 16" of compression and 8" of rebound at combat weight results in 24" of total suspension travel. 
• Fuel capacity: 325 gallons
• Range: ~150-200 miles

 

Armor weight budget:

 

Weight budget

[ApplesauceBandit]

Instead of using this bonus time to write things or polish stuff up, I've instead ended making random things with my existing model.  Made a quick and generic SPG/assault gun variant thing really quick after failing to come up with a welded turret that I liked.

[LoooSeR]

33 minutes ago, ApplesauceBandit said:

Instead of using this bonus time to write things or polish stuff up, I've instead ended making random things with my existing model.  Made a quick and generic SPG/assault gun variant thing really quick after failing to come up with a welded turret that I liked.

 

Spoiler

 

Hey, you stole a new welded turret from North Korean SPG. Now mount double grenade lauchers and MANPADS.

[Zyklon]

Double grenade launchers and Manpads should definatly be a requirement in the next competition

[Sturgeon]

PART FIVE OF FIVE

 

The M12 Donward Heavy Tank: Cascadia's Forgotten Heavy Hitter

 

At the outbreak of the Idaho War, the highly mobile, well-armed forces of the Cascade Republic Army devastated poorly-equipped and supplied Deseret expeditionary in the Idaho territories. Cascadian troops armed with advanced M64 automatic rifles overwhelmed Deseret soldiers, who were largely still armed with post-war manufactured bolt action weapons. Advanced M13A4 Sandy Light Tanks, sporting armor too tough for most Mormon weapons to penetrate and guns that were effective against the defender's tanks themselves, shocked Deseret positions, while the lighter M13A6 Sandy Airmobile Tanks surprised and disrupted Mormon units from behind their own lines. However, by late 2249, Cascadian forces found themselves bogged down in fighting near the Snake River, in the Southern Idaho territory. Mormon fanatics had entrenched there, utilizing an extensive set of reinforced concrete bunkers built along the northern edge of the Great Basin. These bunkers, constructed decades earlier, allowed the Mormon forces to hold off the Cascadian military just north of the Idaho-Utah border.

 

 

An XM12E4 Donward Heavy Tank during a scenic demonstration to CR Army top brass in front of the Cascade Range in March 2250.

 

Responding to this, the Cascadian Army Ordnance Corps issued an emergency request for a new "breakthrough" tank which could attack fortified Cascadian positions while also having the capacity to deal with the new heavily armored Elijah tanks just reaching Mormon forces at the front. To abridge development, Chief of Cascadian Armor Ordnance Quentin Garland directed private companies to submit off-the-shelf designs armed with the new Ordnance XM59 152mm cannon. Two firms responded, Cascadia Land Industries with its Roach-152 proposal, and Bureau 39, which proposed a version of the XM12E2 Donward armed with the gigantic cannon. Of the two, the 152mm-armed Donward was deemed to have significantly lower development time and superior crew ergonomics, due to its larger turret and more ample space for the large two-piece 152mm ammunition. Bureau 39's proposal was accepted, and designated the XM12E4 Donward Heavy Tank. The original XM12E3 120mm gun-armed prototype was converted to mount the massive new 152mm gun, and used for concept validation and gunnery trials. At the conclusion of those trials in May 2250, that first XM12E4 prototype was demonstrated to top CR Army brass at the demonstration field near the Cascade Range. It was subsequently put into series production as the M12A4 Donward Heavy Tank, with the first 9 tanks (often erroneously often referred to as XM12E4s) being converted from the existing XM12E1, XM12E2, and XM12E3 prototypes. A further five unused armor test castings were fully finished and converted to M12A4 standard and sent to the Mormon Front.

 

 

XM12E4 Donward on troop trials exercises near Seattle, Cascade Republic, 2249.

 

These fourteen tanks reached the front in July of 2250, during the biggest offensive mounted by Mormon forces so far in that war, known to historians as the Battle of Burley. The M12A4 Donward Heavy Tanks proved to be an essential element in the Eastern Expeditionary Corps (EEC) - up till that point equipped only with M13A6 Sandy light Tanks -  being able to turn the tables and beat back the Mormon offense. Mormon forces inflicted heavy casualties on CR Army units, but the offense was defeated and the Deseret Army was unable to mount any offenses of comparable size for the rest of the war. Meanwhile, elite Heavy Tank Units equipped with Donward tanks were able to break through heavily fortified Mormon positions, and over the next year the CR Army drove the Deseret Expeditionary Corps back to Salt Lake City. M12A4 Donward Heavy Tanks were also used heavily in the Arizona campaign, pushing through Monument Valley towards Moab.

 

 

An M12 Donward Heavy Tank fights near Monument Valley, Deseret, in the final months of the Idaho War, 2251.

 

After the surrender of the Deseret government in 2251 and the conclusion of major fighting in the Idaho War, the Armored Force began a reorganization as part of a pivot towards combating Californian forces. As a result, the Heavy Tank units that had been so effective were disbanded, and the 85 M12 Heavy Tanks that equipped them put into mothballs. Instead, the Armored Force would be equipped solely with the newly redesignated M15A2 Roach "Main Battle Tank", which had been introduced as a medium tank in the last year of the Idaho War.

 

 

M12A4 Donward Heavy Tank

 

 

GENERAL CHARACTERISTICS

Crew: 4

Length (gun forward): 11.54 m

Length (gun to rear): 10.52 m

Length (w/o gun): 7.37 m

Gun Overhang (gun forward): 4.17 m

Width (over skirts): 3.47 m

Width (without skirts): 3.35 m

Height (to roof): 2.61 m

Height (to 7.62 MG): 2.95 m

Ground Clearance: 0.61 m

Turret Ring Diameter (inside): 85 in

Weight, Curb: 43,320 kg

Weight, Gross: 46,749 kg

Power to Weight Ratio (gross): 16.0 hp/t

Ground Pressure: 11.7 PSI

PROTECTION

Hull armor:

Upper glacis - 4.4" at 28 degrees - 239mm LOS (slightly elliptical)

Lower glacis - 3" at 44.6 degrees - 108mm LOS

Side - 2" at 15 degrees, plus 1" side skirts spaced at 22-38" - 78.4mm LOS

Turret armor:

0 degrees: 512mm at forehead, 240mm at nose, 186mm above ring

15 degrees: 502mm at forehead, 220mm at nose, 167mm above ring, 339mm sides

30 degrees: 358mm at forehead, 200mm at nose, 147mm above ring, 175mm sides

45 degrees: 262mm at forehead, 154mm at nose, 136mm above ring, 124mm sides

ARMAMENT

Primary: 152x923mmR M59 L/48.5 Loading-Assisted Rifled Gun 

    Traverse: Electrohydraulic and manual, 360 degrees

    Traverse Rate (max): 24 d/s, 15 seconds/360 degrees

    Elevation: Electrohydraulic and manual, +25/-10 degrees

    Elevation Rate: 10 d/s

    Firing Rate (max): 3 rounds/min

    Stabilizer: Vertical

Secondary:

    (1) 7.62mm M240 machine gun, coaxial
    (1) .50 caliber M2 machine gun, commander's hatch
    (1) 7.62mm M240 machine gun, loader's position
    Provision for (1) 9mm M95 Submachine Gun
    

AMMUNITION

    36 rounds 152x923mmR
    800 rounds .50 caliber
    6,000 rounds 7.62mm (coaxial)
    1,200 rounds 7.62mm (loader)
    210 rounds 9mm
    24 smoke grenades

FIRE CONTROL AND VISION EQUIPMENT

Primary Weapon:

    Direct: Gunner's Primary Sight
        Gunner's Auxiliary Sight
        Ballistic Calculator
        Stereoscopic Rangefinder

    Indirect: Azimuth Indicator
          Elevation Quadrant
          Gunner's Quadrant

Vision Devices:

    Driver: Periscopes (3), Night Vision

    Commander: Periscope Vision Blocks (7), Rotatable         
    Periscope (1), Weapon Sight (1)

    Gunner: Gunner's Primary Sight, Gunner's Auxiliary Sight

    Loader: Periscope (1)

POWERPLANT

750 hp air-cooled turbocharged V12 diesel, 29.4 L displacement,
cross-drive transmission

[Sturgeon]

FINAL SUBMISSIONS

 

PART ONE: The XM12 Donward: Cascadia's First Main Battle Tank? (1/2)

 

PART TWO: The XM12 Donward: Cascadia's First Main Battle Tank? (2/2)

 

PART THREE: The XM15 Roach: Cascadia's Chariot of Victory

 

PART FOUR: The Airmobile Armor Corps: A Retrospective of the "Sandy" Light Tank

 

PART FIVE: The M12 Donward Heavy Tank: Cascadia's Forgotten Heavy Hitter

 

AMMO DATA SHEET

 

 

Judges, please note that there's been minor polishing, editing, and continuity fixes that have been done to all of the older posts, so each post may be worth another skim.

[Sturgeon]

HOLY MORMON WAR DEPARTMENT BULLETIN

 

PRODUCED BY THE DESERET HEAVENLY VOICE

 

2251

 

INFANTRY WEAPONS OF THE CASCADIAN HERETICS

 

IT IS THE DUTY of all the blessed Latter Day Saints to commit fully to holy war to defend our homeland in the New World. For those Saints who choose to do this by taking up arms, it is essential that you receive unto yourself knowledge of those arms made and used by the Cascadian heretics so that you may both counteract them and pick them up, operate them, and turn them against their heretic creators themselves. Therefore, pay heed to the knowledge contained herein and receive the power inside yourselves to fight in holy war for the forces of God!

 

HERETIC PISTOLS

 

The Cascadian heretics employ a number of pistols including both current and obsolete types. The oldest type in common service is the M2153 Revolver, an eight-shot .35 caliber weapon engineered for longevity and ease of production. M2153 revolvers were produced by hand in small shops within the Heretic Republic, and broken revolvers must be repaired in similarly equipped facilities. However, these revolvers do last for a very long time, and heretics can be seen wielding them in the current day, despite production ending in the 2190s. In the 2180s, the Cascadian heretics introduced a new pistol, the M2182 Automatic Pistol, which introduced a 15-shot detachable box magazine coupled with a straight blowback slide-operated action. Like the M2153, this is chambered in .35 caliber, and was made in large numbers on heretic production lines until the 2220s. The newest heretic pistol is a .35 locked-breech design that is much lighter and easier to shoot than its predecessor, but still uses backwards compatible 15-round magazines of basically the same pattern. It follows the current heretic naming scheme, and is called the M12 Automatic.

 

Saints who employ any of these heretic pistols against their oppressors are encouraged to use surprise and ambush tactics and to obtain a more effective weapon, such as a rifle or scattershot, posthaste.

 

HERETIC RIFLES

 

Since their conquest of the Northwest region, the Cascadian heretics have used a variety of different rifles to oppress Saints within their sphere of influence. Besides a motley of leftover pre-war rifles, the Heretic Army has employed a standardized bolt action rifle chambered in .30x2 caliber since the 2160s. This rifle, the M2164 Repeating Carbine, replaced a previous pattern of bolt action rifle and introduced features like a free float barrel, and a detachable 10 round box magazine. M2164 Carbines are still in service with many heretic reserve and echelon units. M2164 Carbines with a mounted optic are the most commonly seen marksman weapon among heretic forces.

 

Bolt action rifles are best used by Latter-Day Saints who seek to score precise hits at the cost of volume of fire versus the submachine rifle. At very close distances, the bolt action rifle is superior to the pistol, but inferior to the submachine rifle.

 

HERETIC SUBMACHINE RIFLES

 

Submachine rifles have been used by heretic forces to supplement the firepower of bolt action rifles since the 2180s. The earliest of these, the M19 Submachine Rifle, is chambered in .35 caliber and accepts a 32-round detachable "stick" magazine or a 72-round drum magazine, though these latter magazines are now only rarely seen. These are open bolt, straight blowback submachine rifles analogous to our own Creed Submachine Rifle. M19 Submachine Rifles are in second-line use with heretic forces, having been replaced by the newer M56 Submachine Rifle, which does away with the drum magazine and uses a cast aluminum receiver, rather than machined steel. The Cascadian heretics have deceitfully introduced a new submachine rifle just prior to their aggression in the Righteous War, which does not fire any of the pre-war calibers. Capture of weapons and ammunition during the victorious Defense of Zoram in Lee of last year revealed that this rifle is called the "M95", is made primarily of machine steel, is chambered for a new .256-inch caliber cartridge, and uses a box magazine holding 31 rounds. The fact that ammunition containers for these weapons come in lots of 30 rounds only reflects the disorganization and decadence inherent in the heretic system.

 

Submachine rifles are best employed at close ranges as their accuracy  and effectiveness at killing heretics drops off precipitously after 100 yards. However, they can be devastating weapons in a close-in fight.

HERETIC MACHINE RIFLES

 

The Cascadian heretics employ several indigenous patterns of machine rifle, and one pattern stolen from the decadent pre-war USA. Heretics still use 1900s-era M240 General Purpose Machine Rifles for nearly all emplaced automatic weapons and as light infantry weapons at the company level. These weapons are belt-fed, .30 automatic weapons which weigh nearly 30 pounds unloaded, restricting them to being positional weapons only. Although some of these weapons date from before the war, most are post-war copies made within the Heretic Republic itself. Cascadian heretic forces also employ a new magazine-fed pattern of machine rifle, the M61, which also fires .30 ammunition and weighs about 11 pounds unloaded. This weapon is equipped with a bipod, and occasionally an optical sight for the marksman rifle role. Capacity of this weapon is 25 rounds, meaning it runs empty quickly. Most front-line heretic soldiers are now equipped with this weapon.

 

Machine rifles are best employed from static positions due to their weight, although the M61 can also be used in a similar manner to the submachine rifle.

 

NOTES FROM THE OFFICE OF THE CHIEF OF ORDNANCE, CR ARMY

 

August 25, 2251

 

Mormon vernacular can be confusing for Cascadian readers. Sometimes names or common words are substituted for their own queer terminology set. For example, it is evident in the above document that Mormon speakers refer to submachine guns as "submachine rifles", due to language codes which dictate that the word "gun" is a vulgarity. Accordingly, they use the word "scattershot" instead of the more conventional "shotgun". Also, their name for the Battle of Burley is the Defense of Zoram, as they do not use the name Burley for that area and Mormon propaganda holds that their defense was not overwhelmed but resulted in a strategic retreat. Given that the capitulation of the Mormon forces is nearly at hand and is expected within the year, this narrative has proven difficult for the Mormon Elders to maintain. The LDS church uses a different calendar system from the Universal Calendar, which has 14 months named after the 17 pre-war LDS prophets (4 of which were named "Smith", represented by the first month). The month of Lee in the LDS system corresponds roughly to the month of July in Universal. Mormon language codes also dictate measurements in Imperial units only, which results in the translation of common ammunition nomenclature into their own proprietary system. These correspond as follows:

".30x2" or ".30" refers to the 7.62x51mm CR round

".35" refers to the 9x19mm CR round

".25" refers to the new 6.35x45mm CR Assault Rifle round

 

There are also a few errors in the Mormon document, most notably the erroneous description of the M95 Assault Rifle having a magazine capacity of 31 rounds. Capacity of the M95 magazine is 30 rounds, although with some effort a 31st round can be inserted due to the additional space within the magazine.

[Toxn]

2 hours ago, Sturgeon said:

FINAL SUBMISSIONS

 

PART ONE: The XM12 Donward: Cascadia's First Main Battle Tank? (1/2)

 

PART TWO: The XM12 Donward: Cascadia's First Main Battle Tank? (2/2)

 

PART THREE: The XM15 Roach: Cascadia's Chariot of Victory

 

PART FOUR: The Airmobile Armor Corps: A Retrospective of the "Sandy" Light Tank

 

PART FIVE: The M12 Donward Heavy Tank: Cascadia's Forgotten Heavy Hitter

 

AMMO DATA SHEET

 

 

Judges, please note that there's been minor polishing, editing, and continuity fixes that have been done to all of the older posts, so each post may be worth another skim.

I've also been adding to my submisssion a bit.

[ApplesauceBandit]

pew

[Toxn]

13 hours ago, Sturgeon said:

PART FIVE OF FIVE

 

The M12 Donward Heavy Tank: Cascadia's Forgotten Heavy Hitter

 

At the outbreak of the Idaho War, the highly mobile, well-armed forces of the Cascade Republic Army devastated poorly-equipped and supplied Deseret expeditionary in the Idaho territories. Cascadian troops armed with advanced M64 automatic rifles overwhelmed Deseret soldiers, who were largely still armed with post-war manufactured bolt action weapons. Advanced M13A4 Sandy Light Tanks, sporting armor too tough for most Mormon weapons to penetrate and guns that were effective against the defender's tanks themselves, shocked Deseret positions, while the lighter M13A6 Sandy Airmobile Tanks surprised and disrupted Mormon units from behind their own lines. However, by late 2249, Cascadian forces found themselves bogged down in fighting near the Snake River, in the Southern Idaho territory. Mormon fanatics had entrenched there, utilizing an extensive set of reinforced concrete bunkers built along the northern edge of the Great Basin. These bunkers, constructed decades earlier, allowed the Mormon forces to hold off the Cascadian military just north of the Idaho-Utah border.

 

 

An XM12E4 Donward Heavy Tank during a scenic demonstration to CR Army top brass in front of the Cascade Range in March 2250.

 

Responding to this, the Cascadian Army Ordnance Corps issued an emergency request for a new "breakthrough" tank which could attack fortified Cascadian positions while also having the capacity to deal with the new heavily armored Elijah tanks just reaching Mormon forces at the front. To abridge development, Chief of Cascadian Armor Ordnance Quentin Garland directed private companies to submit off-the-shelf designs armed with the new Ordnance XM59 152mm cannon. Two firms responded, Cascadia Land Industries with its Roach-152 proposal, and Bureau 39, which proposed a version of the XM12E2 Donward armed with the gigantic cannon. Of the two, the 152mm-armed Donward was deemed to have significantly lower development time and superior crew ergonomics, due to its larger turret and more ample space for the large two-piece 152mm ammunition. Bureau 39's proposal was accepted, and designated the XM12E4 Donward Heavy Tank. The original XM12E3 120mm gun-armed prototype was converted to mount the massive new 152mm gun, and used for concept validation and gunnery trials. At the conclusion of those trials in May 2250, that first XM12E4 prototype was demonstrated to top CR Army brass at the demonstration field near the Cascade Range. It was subsequently put into series production as the M12A4 Donward Heavy Tank, with the first 9 tanks (often erroneously often referred to as XM12E4s) being converted from the existing XM12E1, XM12E2, and XM12E3 prototypes. A further five unused armor test castings were fully finished and converted to M12A4 standard and sent to the Mormon Front.

 

 

XM12E4 Donward on troop trials exercises near Seattle, Cascade Republic, 2249.

 

These fourteen tanks reached the front in July of 2250, during the biggest offensive mounted by Mormon forces so far in that war, known to historians as the Battle of Burley. The M12A4 Donward Heavy Tanks proved to be an essential element in the Eastern Expeditionary Corps (EEC) - up till that point equipped only with M13A6 Sandy light Tanks -  being able to turn the tables and beat back the Mormon offense. Mormon forces inflicted heavy casualties on CR Army units, but the offense was defeated and the Deseret Army was unable to mount any offenses of comparable size for the rest of the war. Meanwhile, elite Heavy Tank Units equipped with Donward tanks were able to break through heavily fortified Mormon positions, and over the next year the CR Army drove the Deseret Expeditionary Corps back to Salt Lake City. M12A4 Donward Heavy Tanks were also used heavily in the Arizona campaign, pushing through Monument Valley towards Moab.

 

 

An M12 Donward Heavy Tank fights near Monument Valley, Deseret, in the final months of the Idaho War, 2251.

 

After the surrender of the Deseret government in 2251 and the conclusion of major fighting in the Idaho War, the Armored Force began a reorganization as part of a pivot towards combating Californian forces. As a result, the Heavy Tank units that had been so effective were disbanded, and the 85 M12 Heavy Tanks that equipped them put into mothballs. Instead, the Armored Force would be equipped solely with the newly redesignated M15A2 Roach "Main Battle Tank", which had been introduced as a medium tank in the last year of the Idaho War.

 

 

M12A4 Donward Heavy Tank

 

 

GENERAL CHARACTERISTICS

Crew: 4

Length (gun forward): 11.54 m

Length (gun to rear): 10.52 m

Length (w/o gun): 7.37 m

Gun Overhang (gun forward): 4.17 m

Width (over skirts): 3.47 m

Width (without skirts): 3.35 m

Height (to roof): 2.61 m

Height (to 7.62 MG): 2.95 m

Ground Clearance: 0.61 m

Turret Ring Diameter (inside): 85 in

Weight, Curb: 43,320 kg

Weight, Gross: 46,749 kg

Power to Weight Ratio (gross): 16.0 hp/t

Ground Pressure: 11.7 PSI

PROTECTION

Hull armor:

Upper glacis - 4.4" at 28 degrees - 239mm LOS (slightly elliptical)

Lower glacis - 3" at 44.6 degrees - 108mm LOS

Side - 2" at 15 degrees, plus 1" side skirts spaced at 22-38" - 78.4mm LOS

Turret armor:

0 degrees: 512mm at forehead, 240mm at nose, 186mm above ring

15 degrees: 502mm at forehead, 220mm at nose, 167mm above ring, 339mm sides

30 degrees: 358mm at forehead, 200mm at nose, 147mm above ring, 175mm sides

45 degrees: 262mm at forehead, 154mm at nose, 136mm above ring, 124mm sides

ARMAMENT

Primary: 152x923mmR M59 L/48.5 Loading-Assisted Rifled Gun 

    Traverse: Electrohydraulic and manual, 360 degrees

    Traverse Rate (max): 24 d/s, 15 seconds/360 degrees

    Elevation: Electrohydraulic and manual, +25/-10 degrees

    Elevation Rate: 10 d/s

    Firing Rate (max): 3 rounds/min

    Stabilizer: Vertical

Secondary:

    (1) 7.62mm M240 machine gun, coaxial
    (1) .50 caliber M2 machine gun, commander's hatch
    (1) 7.62mm M240 machine gun, loader's position
    Provision for (1) 9mm M95 Submachine Gun
    

AMMUNITION

    36 rounds 152x923mmR
    800 rounds .50 caliber
    6,000 rounds 7.62mm (coaxial)
    1,200 rounds 7.62mm (loader)
    210 rounds 9mm
    24 smoke grenades

FIRE CONTROL AND VISION EQUIPMENT

Primary Weapon:

    Direct: Gunner's Primary Sight
        Gunner's Auxiliary Sight
        Ballistic Calculator
        Stereoscopic Rangefinder

    Indirect: Azimuth Indicator
          Elevation Quadrant
          Gunner's Quadrant

Vision Devices:

    Driver: Periscopes (3), Night Vision

    Commander: Periscope Vision Blocks (7), Rotatable         
    Periscope (1), Weapon Sight (1)

    Gunner: Gunner's Primary Sight, Gunner's Auxiliary Sight

    Loader: Periscope (1)

POWERPLANT

750 hp air-cooled turbocharged V12 diesel, 29.4 L displacement,
cross-drive transmission

For this competition I built a spreadsheet to estimate shells and their pentration using a bunch of approaches.

 

Here's what it spits out for your 152mm gun when I estimate the energy capacity of the case at 10.35 14.24MJ (volume of a 152x923mm tube @ 618 850J/cm3):

 

AP (DeMarre, based on 152mm 1915/28): ~270mm RHA penetration at 500m

APHE (DeMarre, based on 152mm G-530):  ~220mm RHA penetration at 500m

APCR (DeMarre, based on 120mm T17E1): ~190mm RHA penetration at 500m

APCR (DeMarre, based on 105mm PzGr 40): ~290mm RHA penetration at 500m

HEAT (rifled, early, best-fit trendline of historical shells):  ~330mm RHA penetration

HEAT-FS (best-fit trendline of historical shells): ~560mm RHA penetration

APFSDS (optimised using Odermatt equations for jacketed sabot): ~530mm RHA penetration at muzzle

 

Edit: doing some quick calculations, a value of ~850J/cm3 of case capacity is more accurate. The figures have been updated accordingly.

[Sturgeon]

2 hours ago, Toxn said:

For this competition I built a spreadsheet to estimate shells and their pentration using a bunch of approaches.

 

Here's what it spits out for your 152mm gun when I estimate the energy capacity of the case at 10.35 14.24MJ (volume of a 152x923mm tube @ 618 850J/cm3):

 

AP (DeMarre, based on 152mm 1915/28): ~270mm RHA penetration at 500m

APHE (DeMarre, based on 152mm G-530):  ~220mm RHA penetration at 500m

APCR (DeMarre, based on 120mm T17E1): ~190mm RHA penetration at 500m

APCR (DeMarre, based on 105mm PzGr 40): ~290mm RHA penetration at 500m

HEAT (rifled, early, best-fit trendline of historical shells):  ~330mm RHA penetration

HEAT-FS (best-fit trendline of historical shells): ~560mm RHA penetration

APFSDS (optimised using Odermatt equations for jacketed sabot): ~530mm RHA penetration at muzzle

 

Edit: doing some quick calculations, a value of ~850J/cm3 of case capacity is more accurate. The figures have been updated accordingly.

 

 

 

On 9/28/2018 at 11:02 PM, Sturgeon said:

152mm Gun XM59

Loader-assisted or autoloaded 152mm high velocity anti-tank cannon
firing two-piece ammunition.

95lb APCBC shot at 2,953 ft/s

10.5in (267 mm) penetration at 2,000 yd on 20 deg obliquity plate

330mm at 70 degrees at 100 m

303mm at 70 degrees at 500 m

278mm at 70 degrees at 1000 m

274mm at 70 degrees at 1500 m

267mm at 70 degrees at 2000 m

7 kg (11 kg projectile) APFSDS at 5,380 ft/s

~700mm-670mm from 0-2000 m

 

 

Capacity of the case is in fact 21,650 cm^3 (modeled in SolidWorks), and given a 17.4 MJ muzzle energy that gives me a figure of 806 J/cm^3. So your estimates are wrong simply because you underestimated how ridiculous my case volume was, muahahahahah!

 

Your estimates for the APCBC round do seem accurate, if you shift everything about 500 meters back. Given that the muzzle velocity is some 300 ft/s higher than your estimate, that's reasonable.

For reals though, the M59 is a BL-10 proxy.

 

 

[Toxn]

2 hours ago, Sturgeon said:

 

 

 

 

 

Capacity of the case is in fact 21,650 cm^3 (modeled in SolidWorks), and given a 17.4 MJ muzzle energy that gives me a figure of 806 J/cm^3. So your estimates are wrong simply because you underestimated how ridiculous my case volume was, muahahahahah!

 

Your estimates for the APCBC round do seem accurate, if you shift everything about 500 meters back. Given that the muzzle velocity is some 300 ft/s higher than your estimate, that's reasonable.

For reals though, the M59 is a BL-10 proxy.

 

 

It's a potent gun regardless.

 

I've actually just updated my spreadsheet to model non-cylindrical cases (still quite approximately), which will make these sorts of estimates more accurate in future.

[LoooSeR]

Who needs more time to work on their projects? Because you know, 33rd September.

[A. T. Mahan]

I'd like until midnight EST to get the final submission posts done for my two. 

[Collimatrix]

2 hours ago, LoooSeR said:

Who needs more time to work on their projects? Because you know, 33rd September.

 

Don't wait on my account.  I'll get it done eventually, because @Zyklon wanted to see it.  But seriously, my design is silly.  It has interleved road wheels for Morozov's sake!

[A. T. Mahan]

FINAL SUBMISSION: LIGHT TANK

 

 

57mm Gun Full Tracked Light Tank M48A4E4 “Koskiusko”

NorthStar Tractor, a subsidiary of Pacific Car and Foundry

 

Description:

The M48A4E4 is a lightweight, fully tracked, Petrol-powered armored reconnaissance vehicle. It can operate on or off road at high speed over rough terrain in reconnaissance, pursuit, flanking, harassing, target acquisition, deep raiding, air-mobile and other combat roles. It is also air-transportable. Armament consists of a 57mm automatic cannon T33 mounted in a 360 degree rotating turret, capable of firing APHEBC, HVAP, APDS, HE, CAN, and APFSDS rounds; one 106mm Recoilless Rifle M40 mounted in an elevation adjustable mount on the left turret exterior, capable of firing HEAT, HE, APERS, and HEP shells; a caliber .50 Browning mounted on the commander’s hatch for air defense; and a battery of 8 smoke dischargers, mounted turret rear firing forwards over the turret.

 

When directed to develop a light tank according to the Cascadian RFP, NorthStar Tractor decided to use the same tried and true design philosophy which has borne success in the agricultural sector. Where novel gadgetry may amaze and provide incredible paper performance for other submissions, NorthStar Tractor has taken a less foolhardy approach. Wherever possible proven designs, techniques and technologies are applied, often in novel ways or combinations, to achieve the requirements set forth. This is not to imply luddite tendencies. Novel technology is used when it is the best solution, as judged against the teething problems and expense it would incur. The end product is a vehicle which enters service without the teething problems associated with a more novelty focused approach.

 

NST selected the Pre-War Buick 76mm Gun Motor Carriage M18 “Hellcat” as a starting point. Its combination of light weight, high speed, and excellent war record, as well as being significantly under the weight and size requirements, gave the Firm’s engineers the safety margin necessary to freely experiment with design possibilities.

 

Chassis: From the core M18 “Hellcat” chassis has come the general configuration and design of the hull. Some modification has been made, however. The vehicle was experimentally equipped with various engines. These variants are known as the M48, M48A1, M48A2, M48A3, and M48A4 respectively.

 

Designation	Engine
M48	R975
M48A1	Diesel
M48A2	Gas Turbine
M48A3	Hybrid-Electric faildrive
M48A4	Ford GAA

 

On all variants the Assistant Driver’s position has been wholly deleted and  replaced by a Self-Sealing fuel tank, which yields an additional 190 liters of petrol. The suspension and tracks remain the same as on the original M18 GMC, save the torsion bars are of the double acting tube-in-bar design, rather than single.

 

It is the design team’s feeling that armor on a light tank is generally of little and less value. Given the stated threat profile listed in the RFP, and the doctrinal role of the light tank, the M48 has been designed with speed and situational awareness as it’s armor. The steel and aluminum construction of the M48 allows it to withstand small arms fire and shell splinters. To attain a meaningful level of protection against the threats profiled would compromise the mobility which forms the core of the M48. That said, developments in Explosive Reactive Armor (ERA) are being watched very closely, and pending the success of the PACAR-RSL “Contact” system in trials, it will be investigated as a potential way to mitigate the threat of light anti-tank weapons. The production M48A4 will be fitted for but not with the “Contact” armor system.

 

As suits a light tank, the ammunition load and stores capacity should enable the crew to operate independent of resupply for some days. For this purpose the M48 is equipped with Kettle, Electric, Hot Water, M32 with Percolator, Coffee, M30, able to prepare hot beverages and reheat rations.

 

Firepower:

Developed from a fusion of pre-war Soviet and British designs, the 57mm Automatic Gun T33 provides ample anti-armor firepower for the scout role. Upgrades to the T33 gun are underway, utilizing technologies developed for the T44 program to develop both APDS and APFSDS shells for greater penetration. The peculiarities of the magazine system preclude quickly changing the ammunition type, and the 57mm O-271U HE shell was historically lackluster. To offset this, and provide additional close-medium range firepower, M40 106mm Recoilless Rifles are mounted in an elevation adjustable mount on the left side of the turret. For local air defense a Caliber .50 is mounted on a ring above the commander’s hatch. Optional armor kits are in development for this position.

 

The turret of the M18 was deemed insufficient and removed. While it possessed admirable characteristics, it was not designed around the role intended for the M48. That said, the vehicle is backwards compatible, and the M18’s gun and turret can be produced and mounted should the customer desire.

 

The M48 is equipped with the T36 Turret, either the T36E1, armed with the T32E3 gun, or the T36E2, armed with the T33 gun. The T32E3 consists of the 57mm/L50 Anti-Tank Gun M1 design in 57x440mm caliber, mated to the Molins Mk.III Automatic Loader. The T33 is a 57mm/L70 barrel chambered in 57x480mm mated to a modified version of the Molins design. A cyclic rate of fire of 50-60 rounds/minute is possible, with a 24 round fixed magazine. Additional ammunition is carried in the hull.

 

Mounted on the left side of the turret is either the T63 weapons system consisting of two mated 106mm M40 recoilless rifles and a M8C Caliber .50BAT spotting rifle or T64 weapons system consisting of  a single rifle and spotting rifle. The main ammunition for these weapons will be the M581 APERS round with 9.89kg of flechettes, the M344A1 HEAT-FS shell with >400mm of RHA penetration and an effective range of approximately 1300m, or the M346A1 HEP-T shell with a 3.5kg burst charge.

Armament Variants	T32E3 (L50)	T33 (L70)
T63 (2x106)	M48A4E1	M48A4E2
T64 (1x106)	M48A4E3	M48A4E4

 

All variants can mount a Caliber .50 machinegun on the roof pintle.

 

The gunner is equipped with a primary 6x periscopic gunsight, along with a unity panoramic. Rangefinding is stadiometric, with both a 1,5 and 2,7m stadia. The commander is equipped with a traversing binocular periscopic 1.2-4x sight. This unit has two push-button controls, one to stabilize the periscope in azimuth independent of the turret, and one to slew the turret to the commanders sight azimuth. This provides a moderate hunter-killer capacity.

 

The turret bustle contains the radio equipment. A command/FAC/FIST-V design with improved radios is in development as well.

 

Training of the turret is accomplished by an electric system, allowing traverse of up to 30 degrees/s. Elevation is also electric, from -10/+20 degrees. The gun is stabilized in traverse and elevation using a system derived from the RSLW T44 project.

 

Additional stowage is provided for personal weapons and equipment, pioneer tools, camouflage netting, and miscellaneous items.

 

Armor:

The M48 is, practically speaking, armored solely against small arms and artillery fragments. It meets the required specifications of the RFP in terms of armor. Upgrade packages are available, mounting “Contact” or “RAT” Explosive-Reactive-Armor tiles or composite armor packages, however these significantly increase the weight of the vehicle, and compromise its excellent mobility.

 

In house testing at NorthStar Tractor determined that the best combination of reliability, cost, and battle-effectiveness was the M48A4 with engine based on the Pre-War Ford GAA V-8, and generally unmodified transmission. The program manager selected the E2 armament subsystem for proposal.

 

The M48A4E2 meets the specifications of the RFP:

• The combat weight of 19,000 kg is 6 tons below specification (17% underweight)

• The width, c. 113”, is under the c.130” limit

• The upper glacis and frontal turret armor are 1” thick, not including add-on packages

• The 12.7mm side armor is 2.7mm above specification

• The power:weight ratio (500hp : 19,000kg) of 23.87 hp/t is approximately 198% of the Power:Weight requirement

• The 3 man crew is 50% of the requirement

• The primary armament, 57mm Automatic Gun T33, can fire both HE and AP shot and shell, while the 106mm M40 can fire HEAT, HEP, HE, and APERS.

 

 

---

57mm Gun Full Tracked Light Tank M48A4E2

 

 

 

GENERAL CHARACTERISTICS

Crew: 3 (Driver, Gunner, Commander)

Length: 6.6m (gun forward), 5.28m (hull)

Width: 2.87m

Height: 2.6 m

Ground Clearance: 0.36m

Turret Ring Diameter (inside): 69 in

Weight, nominal empty: 18,000 kg

Weight, full load: 19,000 kg

Power to Weight Ratio (gross): 21 hp/t at 19,000kg

Ground Pressure: .885kg/cm^2 empty weight (zero ground penetration)

 

PROTECTION

Hull armor:

Upper glacis - 12.7mm steel + 12.7mm Aluminum

Lower glacis - 12.7mm steel

Side / Rear - 12.7mm steel

Turret armor:

Front Face 25.4mm steel

Sides and Rear 12.7mm steel

 

ARMAMENT

Primary: 57x480mm L/70 Automatic Gun T33

Traverse: Electric, 360 degrees

   Traverse Rate (max): 30 d/s, 12 seconds/360 degrees

   Elevation: Electric with manual backup, +20/-10 degrees

   Elevation Rate: 15 d/s

   Firing Rate (cyclic): 55 rounds/min

   Stabilizer: Vertical and Horizontal

Secondary:

   (2x) 106mm M40 Recoilless Rifle, Slaved to gun, mounted on turret side.

   (1x) .50 caliber M2 machine gun, Ring mount for commander

   Provision for (3) Cascadian Republic Submachine Gun, Cal. 9x19mm, M56 or equivalent

 

AMMUNITION

   72 rounds 57x480mmR (APHE, APCBC, HVAP, APCR, HE-FRAG, CANN, APFSDS-T)

   6 rounds 105x607mmR [106mm Recoilless] (HEAT, HE-P, HE, APERS)

   800 rounds 12.7x99mm

 

Optics

Gunner's 6x Primary Telescopic Sight

  Gunner's 1-4x Auxiliary Periscopic Unity Sight

  Built in Stadiametric Rangefinder

Commander

1.2-4x Periscopic stabilized sight

 

Vision Devices:

Driver: Periscopes (3), Provision for I2 or IR NV systems

Commander: Binoculars

  Gunner: Gunner's Primary Sight, Gunner's Auxiliary Sight

  

POWERPLANT

Ford GAA, 500hp @2600RPM

 

 

---

[A. T. Mahan]

FINAL SUBMISSION

 

120MM GUN TANK T44

Renton Shipbuilding and Locomotive Works

A Pacific Car and Foundry Company

 

The 120mm Gun Tank T44, designed primarily by the Renton Shipbuilding and Locomotive division of Pacific Car and Foundry, is a fully-tracked armored fighting vehicle armed with a 120mm smoothbore gun. Research and exploratory investigation determined that there were a number of designs and concepts with great potential to leverage and improve the combat effect of the vehicle. The most promising hull that PACAR-RSL located was the M47 Patton -- the combination of castings and weldments of high-quality steel was well within the production capabilities of our facility, and the vehicle weight of 90000lbs would be able to be reduced sufficiently to meet the required weight limit. Noting that the vehicle weight specified in the contract (90,000lb) does not specify whether it is the unloaded or loaded weight, the Program Manager determined that it specified the unloaded weight. In any event, PACAR-RSL has several proposed variants (and has produced prototypes of them) that meet varying weight goals.

 

Structure:

The original M47’s structure is highly dated. While PACAR-RSL has substantial experience with high-quality castings of the scale required, and while PACAR produced M26 Pershing 90mm gun medium tanks in 1944 and 1945 (and retains sufficient quantities of the technical data package to resume production of mildly improved versions of those tanks if the Government would so desire), castings are not compatible with the composite armor techniques that PACAR and our subcontractors have developed based on combat-proven prewar efforts. As a shipbuilding concern, PACAR-RSL possesses substantial experience producing high-quality weldments of extremely high grade steels, and many of our welders are certified to weld armor steels. This trained and capable workforce allowed our design team to rework the monocoque (armor-as-structure) hull and turret of the M47 to suit both the HAP-1 derived armor package and to lighten the vehicle. This resulted in an allowable armor weight of nearly 10,000lb for the hull, sufficient to utilize the HAP-1 armor on a recontoured lower frontal hull.

The hull itself is constructed of welded 1.0” to 1.5” (+/- 0.05”) high strength steel plate,

The turret is of a completely new, all-welded design heavily inspired by the pre-war Abrams design, as far as general shape is concerned.

 

Protection:

 

Central to our design is the incorporation of highly advanced composite armors to reduce the threat of shaped-charge warheads. Pre-war literature indicated that these antitank munitions were most concerning for designers of the so-called first and second generation of main battle tanks, due to their light weight and relatively high penetrative ability, and Cascadian control of the only large supplies of depleted uranium and tungsten in the region result in a greatly reduced threat from long-rod fin-stabilized discarding sabot kinetic penetrators. In cooperation with the Pacific Aero Products Company of Seattle, we have spent considerable time and effort developing ceramic and other composite armor technologies, and believe that we have managed to develop an armor package similar in concept to the BRL-1 and HAP-1 armor packages used on various models of early model pre-war M1 Abrams tanks. Our testing has determined that the armor package we have chosen for the vehicle is substantially lighter and more protective than rolled homogeneous steel or cast steel armor, although it is bulkier and substantially more expensive. The armor utilizes combinations of three types of Non-Explosive Reactive Armor (NERA) packages, the Type I array of three thin parallel sandwiches of 5083-H32/elastomer/5083-H32 mounted on large pre-compressed coil springs, the Type II array of layered ceramic/5083-H32/elastomer/5083-H32 sandwich plates mounted at an angle such that an incoming projectile from within 15 degrees of horizontal must penetrate a minimum of four panels, and the Type IIIA/B composite array. We utilize two different composite arrays. The Type IIIA, used on the turret face, consists of a layer of ceramic tiles, a fiberglass-reinforced polymer backer, a layer of elastomer, a layer of depleted uranium, a fiberglass-reinforced polymer backer, a layer of high hardness armor steel, and the hull structure. The Type IIIB, used on the turret sides and lower glacis plate, is the same as that on the turret face, except the depleted uranium is replaced with high hardness steel. This reduces protection against kinetic energy penetrators, but greatly reduces weight, as high hardness steel is 60% lighter than depleted uranium, and the protection is still very good.

 

We have been particularly focused on Carborundum (Silicon Carbide) as the ceramic used in the armor, although experiments have determined that Boron Carbide offers more protection, but is substantially more difficult to manufacture and work with. While large quantities of B4C exist at the Hanford Site in the form of neutron dampers and shielding, and control rods, they would require substantial effort to form into a usable armor material and at this time the yield rate on B4C tiles of the appropriate size is low to the point of total impracticality - at best, we have determined that current technology will produce no more than 5% of a given batch of tiles that meets QA/QC. We have therefore determined that the most weight and efficient armor scheme would be to more-or-less duplicate the HAP-1 armor construction, substituting Silicon Carbide for Boron Carbide where appropriate, and utilizing the supplies of depleted uranium available at the Hanford Site (estimated to be 2,380 tons, appropriate for approximately 750 vehicles based on current projections of 6000lb of DU per vehicle) would provide substantial kinetic protection at the cost of increased weight.

Our armor concept, admittedly very heavily inspired by that of the early M1 Abrams designs, provides significant protection for its weight, especially considering the smaller protected volume and reduced level of protection chosen. The turret faces are intended to provide protection equivalent to 20-25 inches of rolled homogeneous steel, but are some 70% lighter.

We would note that the Cascadian Government should seek to acquire access to greater supplies of uranium for use in this and other defence programs, and note that research indicates four thousand tons of dry-cask stored spent nuclear fuel each in the former Illinois, former Pennsylvania, and former South Carolina regions and between 3,000 and 4,000 tons each in California, former Alabama, Florida, New York, and Georgia regions. While most of these areas are over a thousand miles away, if Cascadia can secure access to these supplies, they represent approximately 32,500 tons of highly enriched uranium, which would be invaluable for reprocessing into depleted uranium for tank armors, or Special Materials for use in other programs. PACAR-RSL has been making inquiries through traditional trade channels as to the feasibility of cross-country transportation of these materials, but government support would aid the endeavour greatly.

It is worth mentioning that this armor design package more-or-less requires the production of a gaseous-diffusion uranium enrichment cascade and the production of weapons-grade uranium. This could be expected to produce 16.9 tons of U-235, enough for over two thousand 25-kiloton nuclear devices.

Further protection comes from the incorporation of Contact and Rat, explosive reactive armours derived from the Soviet Kontakt-family tiles. Similar except for size and shape, these require no outside initiation, being a box with two steel plates sandwiching a piece of explosive. Contact is used primarily on the turret face, bow, hull, and turret sides, while Rat, derived from the curved tile of the pre-war US Army M19 ARAT tile, is used only on the hull and turret sides as an up-armor kit. Each Contact tile is 12” wide, 6” tall, and weighs 12.5lb. Each Rat tile weighs approximately 40lb, is 20” tall, 15” wide, and mounted on a hinged bracket that allows them to be angled vertical, or angled about 15 degrees down. This reduces the danger to supporting infantry posed by the tile’s detonation. The 238 Contact and 47 Rat tiles able to be mounted on the vehicle only add a maximum of 4,900lb including mounting hardware while providing greatly increased protection.

Contact explosive reactive armor tile (12"x6", 12.5lb)

Rat explosive reactive armor tile (15"x20", 40lb)

 

The armor layout is as follows:

• Turret

  • Turret face:

    • 0.75” HHS face armor, Type I array, Type II array, Type IIIA array, 1” RHA structure

      • 16" RHAe kinetic, 30" RHAe chemical

    • 14 tiles per side of Contact, 28 total

      • Contact tiles provide 14" RHAe against single-stage HEAT threats, ~4" RHAe against full-caliber kinetic threats. 

  • Turret side:

    • 0.75” HHS face, Type I array, Type II array, Type IIIB array, 0.75” RHA structure

      • 12" RHAe kinetic, 27" RHAe chemical

    • 11 tiles Contact and 7 RAT tiles per side, 22 Contact and 14 RAT tiles.

      • RAT tiles provide 18" RHAe against single stage HEAT warheads, 20" RHAe against full-caliber kinetic threats, and decrease the efficacy of subcaliber kinetic threats by 15%. This is due to the greater thickness of steel in the tile. 

  • Turret rear:

    • 2.25” HHS over 0.75” RHA

      • 3.5" RHAe

  • Turret roof:

    • 1.0” HHS

      • 1.2" RHAe

    • 28 Contact tiles

• Hull

  • Upper glacis plate:

    • 3” HHS plate sloped at 80 degrees from vertical (17” LOS)

      • 20" RHAe line of sight

    • 44 Contact tiles

  • Lower glacis plate:

    • 0.75” HHS plate, Type I array, Type II array, Type IIIB array, 1” HHS hull

      • 12.5" RHAe kinetic, 27.5" RHAe chemical

    • 5 tiles Rat

  • Hull Side:

    • 2.25” HHS over 0.75” RHA

      • 3.5" RHAe

    • Up-armor side-skirts consisting of a Type I array

      • 5" RHAe kinetic, 11" RHAe chemical

    • 70 tiles Contact per side plus 28 tiles of RAT

  • Hull rear: 2.0” RHA

  • Hull bottom: 0.75” HHS

    • 0.9" RHAe

  • Hull roof: 0.75” HHS

    • 0.9" RHAe

 

Firepower:

Other work with the Pacific Aero Products Company focused on the development of improved ammunition designs. PACAR-RSL leveraged PAPC’s advanced aerodynamic analytical techniques to aid in the development of improved fin-stabilized smoothbore ammunition. Research on prewar technologies demonstrated a number of programs conducted by the prewar US Army that incorporated smoothbore guns, and industrial analysis has determined that a maximum chamber-pressure of 55,000psi is within current capabilities, and based on research trends in metallurgy, a chamber pressure of 75,000psi should be achievable within five years, and 100,000psi in ten years. While this will result in a lengthened gun compared to prewar designs (The M256 120mm gun was only a 44-caliber gun), a 50-caliber 120mm gun with a tube weight of not more than 2,900lb and an all-up weight of not more than 4,400lb is entirely viable.

We have developed a gun, the 120mm Gun T123E7, that produces a muzzle energy of 4,300 ft-ton with a 50lb armor-piercing capped, ballistic capped projectile (MV = 3,500ft/sec, 50lb shot M358). We estimate that this will drive a 22lb Hanfordite (U-238) penetrator at approximately 4,500ft/sec, giving the capability to defeat greater than 25” of rolled homogenous steel at 2,000 yards, and greatly simplifying the design of the ballistic computer. It uses a vertically sliding breechblock reverse-engineered at great length from surviving examples of the Watervliet Arsenal-produced M256 120mm gun. While the current metallurgy and QA/QC is not sufficient to produce breech blocks capable of the 135,000psi of M256, we believe that with advances in electronically controlled machining, it is feasible. We are planning an exploratory expedition to the Watervleit Arsenal area to gain what prewar technical data we can, particularly on the M256 and M360 guns.

Gun, Smoothbore, 120mm T123E7 (120x570R, L/60)

T123E7 is a 60-caliber 120-mm smoothbore gun with a vertically sliding breechblock, hydropneumatic recoil mechanism, and chrome-lined bore. It has a fume extractor to reduce the rate of propellant gas ingress into the turret, and a thermal sleeve to stabilize the temperature along the bore and reduce bore irregularities due to thermal expansion. It fires 120x570mm fixed ammunition using a cellulose-fiber combustible cartridge case with a metal base cap, reducing the weight of the cartridge case by some 30lb compared to a brass case (107lb for brass case M358 APC-T vs ~55lb for T494 APFSDS-T). Decreased AP projectile weight due to the usage of armor-piercing fin-stabilized discarding sabot ammunition further reduces the weight of the armor-piercing projectile by nearly half, from 50lb to 26lb.

 

 

120mm Ammunition: (L to R) XM441 HEAT-FS (35lb projectile, 3500ft/s MV, M358E1 APC-T (50lb projectile, 3,500ft/s MV), XM442 APFSDS-T (22lb penetrator, 4,400ft/s MV), and a 120mmx575R case

 

Additional projectiles, such as HEP-FS-T and HE-FRAG-FS-T are under development, as are training projectiles.

 

The gun and mount are electrically driven in train and elevation via a geared drive and proportionally controlled motors derived from a mixture of naval fire control equipment and aircraft gun turrets. This had an added benefit of easing the development of an analog two-axis gun stabilization system. The fire control system is electromechanical and analog-electronic, and consists of four components: the T92D gunner’s articulated periscope, the T19 automatic stereoscopic rangefinder, the electrical gun drive, and the T14 gun computer. The gun computer is a miniaturized transistorized electromechanical and analog-electronic computer that incorporates ambient temperature, range as measured from the stereoscopic rangefinder, and the average rate of traverse of the gun over the past one to three seconds to apply lead, cant and Coriolis correction, and superelevation, and align the gun to the sights. When the firing switch is depressed, a set of microswitches delays completion of the firing circuit until the sights are properly aligned, aiding in firing on the move or from a short halt. The gunner’s articulated periscope is a combination 1x-3x variable power unity sight and 3-20x magnified sight, with coated lenses, reticle illumination, and incorporating image intensifying night vision equipment. The image intensifying system is mounted at the end of the optical train, allowing the gunner to use the full magnification range even in reduced lighting conditions. The T19 rangefinder is mounted across the width of the turret and is a 108” base stereoscopic rangefinder equipped with an electro-optical automatic ranging mechanism.

 

Using the following equations, from Material Testing Procedure 3-2-702 (US Army Test and Evaluation Command, Common Engineering Test Procedure for Optical Rangefinders, 20 Apr. 1966, Aberdeen, Maryland), we calculate the T19 rangefinder has a mechanical accuracy of [x] meters. 

For a base length B of 2.769m, a range R1 of 2,000m
[math goes here]

 

The rangefinder can be used by the commander in the manual mode to either produce a more accurate ranging solution and in the event of automatic ranging mechanism failure. Both the commander and gunner can use the rangefinder, although as the fire control system is designed around and as-yet unproduced laser rangefinder, the primary control of automatic rangefinding is on the gunner's controls. The T14 gun computer can also accept manual input of range information via a dial, in 100-yard increments. The automatic mechanism is derived from Leika’s work in camera autofocus mechanisms, and is based on a small array of lead (II) sulfide photosensors similar to those used in early-model AIM-9 Sidewinder air-to-air missiles and a very simple electrical circuit. Early testing has determined that it can resolve ranges with a similar accuracy as a human operator in ⅓-½ the time, depending on the skill of the human operator. The turret and rangefinding system is also designed for-but-not-with a laser rangefinder, which would replace the optical rangefinder and improve gun depression from 12 degrees to 14 degrees. A laser rangefinder similar to the prewar AN/VVG-2 (Ruby, 694.3nm, 50mJ pulse, 125J maximum output) as used in the M60A3 would reduce the ranging time to 1.5 seconds and reduce the typical ranging error from several hundred yards to tens of yards. The ranging time is currently the largest component of the firing sequence, as the design of the T14 gun computer requires it to constantly update the firing solution for all inputs except range and lead, and lead correction is applied more-or-less instantaneously upon depression of the gunner's automatic ranging switch. 

• The T123E7 120mm smoothbore gun is provided with 56 rounds of ammunition in a blow-out protected bustle rack and twenty-four rounds in supplementary ammunition racks to either side of the loader, a total of 80 rounds.
• There is a 7.62mm M240 machine gun mounted coaxially to the main gun, with 8,000 rounds of 7.62x51mm (2,000 ready).
• There is a 7.62mm M240 machine gun provided for the loader mounted in a race-ring mount around his hatch with 2,000 rounds of 7.62x51mm (200 ready)
• There is a .50 M2 machine gun provided for the commander on a ring mount around the commander’s cupola with 2,000 rounds of .50 ammunition (100 ready)
• Provision is made for the storage of the crew’s individual weapons and field equipment, including four rifles and ammunition.

 

Mobility:

T44 uses a torsion-bar suspension, with six individually sprung road-wheels per track connected to double-acting bar-in-tube springs providing substantially improved suspension travel to the original single-acting suspension.

There are two powertrains currently proposed. The first, a prewar design Continental AVDS-1790-5B is a known quantity, an extremely reliable and widely used turbosupercharged diesel V-12 producing 810 horsepower at 2,400RPM. This, in combination with the CD-875-2 four-speed automatic transmission produces a maximum speed of 35 miles an hour on road, and the improved double-acting torsion bar suspension provides an increased rough-terrain speed of approximately 12 miles per hour, compared to nine miles an hour for the Medium Tank M4. This gives the vehicle a combat range of approximately 430 miles with 310 gallons of Diesel fuel.

 

The second powertrain is derived from prewar work on gas turbines. It is a simple, reliable gas turbine of 65” length and 25” diameter that, due to manufacturing limitations, only produces about 1,000 horsepower. Similar prewar designs produced approximately 1,500 horsepower in ground use and 1,800 horsepower in aviation use, but due to manufacturing limitations and for safety reasons, the turbine is limited to 1,200hp SHP emergency power for ten minutes, and 1,000 horsepower maximum. This drives a CD-1100-4F2 crossdrive automatic six-speed transmission (four forward, two reverse), resulting in a maximum road speed of 48 miles per hour and a rough-terrain speed of 22 miles per hour, although crew comfort is a significant concern and shock absorption is an issue at such speeds. This engine, with the associated APU, gives the vehicle a combat range of approximately 375 miles, although with greater speed than the AVDS-1790.

The strategic mobility of the T44 tank is provided by the vehicle’s high speed and substantial reliability. Rail transport of the T44 requires removing the side-skirts and side explosive reactive armor tiles, requiring one hour per vehicle plus a wrecker capable of lifting 1,300lb. Alternatively, the vehicle can be road-marched in combat condition. 

 

In summary, the T44 medium tank meets all of the required design specifications:

• It is 90,000lb unloaded, and 128,000lb at combat weight.

• The fenders fold up to ensure a 129” maximum width (otherwise 135” width)

• The upper frontal plate is 3” thick sloped at 80 degrees from vertical, giving an effective line of sight thickness of 17”

• The side armor is 3” thick

• The power to weight ratio is at worst 16hp/ton (loaded, 810hp engine) and at best 19.6hp/ton

• The tank has a crew of four: Driver, TC, gunner, and commander.

• The primary armament, 120mm gun T123E7, is capable of firing both antiarmor and high explosive projectiles.

• 9ft 8” tall

 

120mm Gun Tank T44 specifications:

• Empty weight: 94,000lb
• Operating empty weight: 109,250lb
• Combat weight: 128,000lb
• Height: 116"
• Width: 168.639 inches
• Length: 233.5" (hull), 415.5" overall, gun forward.
• Ground clearance: 21" at combat weight, less at OEW.
• Engine: Pseudo-Lycoming T53, 750lb/1,000shp
• APU: Two-stroke 25 horsepower Yamaha outboard powerhead
• Transmission: CD-1100-4F2. Four speeds forward, two reverse. Automatic crossdrive transmission. Engine and transmission are a powerpack. 
• Track: Modified T158 track, cut down to 23" wide. 
• Suspension: 74" long bar-in-tube double acting torsion bars, friction snubbers on the first two and last two pairs of road wheels each side (duals on the first road wheel), shock absorbers on the first, second, fifth, and sixth road wheels each side. Three return rollers each side. A total of 16" of compression and 8" of rebound at combat weight results in 24" of total suspension travel. 
• Fuel capacity: 325 gallons
• Range: ~150-200 miles

 

Armor weight budget:

 

Weight budget

[ApplesauceBandit]

Can't post your submission late if it's not a submission!

 

XM42 "Prettyboy"

 

Drafted up by students from the Tacoma School of Science and Technology as an extra credit assignment, the XM42 never left the drawing board. 

 

The XM42 was designed primarily with fire support in mind.  For more mountainous regions, it would be able to provide heavy firepower with greater ease than larger vehicles would.  Against the more mobile Mormon forces, the XM42 would be able to more readily respond to threats while still being adequately protected against many of the threats that it would face.

 

While not being capable of withstanding heavy fire, the XM42's armor would still be able to stop fire from lighter (and more mobile) threats.  

The turret is designed to be protected against 40mm cannon fire from 100m in a 60° arc.  From the sides and rear, it is protected against .50 machine gun fire from 100m.

The hull is frontally protected against 20mm cannon fire from 100m in a 90° arc (only 60° arc with engine compartment area).  The crew is protected from the sides against .50 machine gun fire from 100m whereas the engine is only protected against small arms.  Screens can easily be added to the hull and turret to provide protection against handheld antitank rockets.

 

Armed with a 3" cannon roughly analogous to the M32A1 76mm gun from before The Happening, the XM42 would be fully capable of taking out any armored fighting vehicle currently being fielded by hostile forces.  Elevation values of -12°/+25° allow the XM42 to better handle combat in the more mountainous regions where combat is expected with Commifornian forces.  A modified M240 is mounted coaxially to the main weapon.  A mount on the turret roof exists for using an M2 heavy machine gun.  58 rounds for the main gun are stored both to the driver's side and in the turret basket.

 

The vehicle was to be crewed by 4 men: a driver, gunner, loader, and commander.  A radio is in the turret bustle directly behind the commander's and loader's positions.  A large ventilation fan is located towards the rear of the turret to aid in crew comfort and to remove fumes from the fighting compartment.

 

The engine was envisioned as 500hp, providing the tank with around 20 hp/ton, allowing it to better navigate difficult terrain and to react quickly to threats.  The transmission is located in the rear of the vehicle with the engine.  The running gear has 5 moderately sized roadwheels on either side, sprung with torsion bars running the width of the vehicle.  A large plate on the rear hull may be unbolted and folded down to ease maintenance if needed.

 

(exact numbers don't exist since I only made this in 3ds max, hence the nickname given.  Numbers were compared to the M41 since they're very similar designs.  The XM42 is assumed to be a somewhat more lean and mean fighting machine)

 

Spoiler

 

 

"Peek-a-boo!"

(The commander looks like he'd have to poke his head out if he wanted to look around while the tank is hulldown.   Oops!)

 

 

A fire support version with a 4" howitzer mounted in a newly-designed, fully-traversable turret was also discussed.  This variant would have been capable both of direct and indirect fire, allowing it to either serve as a mobile artillery or to provide heavy fire support for troops in areas where the heavier Cascadian 45 ton tanks would be unable to operate.  While the turret is fully enclosed for better protection of the crew, provisions were made for large hatches on the turret's roof.  The new turret is only capable of withstanding 20mm fire frontally, as opposed to the 40mm fire of the base XM42.

 

Other versions considered but not drawn include a turreted SPAA with twin 40mm cannons, a utility variant capable of being outfitted for different roles (ARV, armored tractor, engineer vehicle, etc.), and a non-turreted SPG variant with either a long 4" gun or a 6" howitzer.

 

 

 

I won't stop you from taking this as an actual submission, I personally am entering this both for fun and to keep in practice with modeling.  I do realize this was submitted a few hours past the deadline too.  As I was about to submit this reply, I noticed that I messed up the shape of the exhaust pipes.  Oh well.

[A. T. Mahan]

 

Flavor text: 

 

Excerpts from Snapshots: The Combat Record of the Medium Tank M4 As Told by The Crews That Fought Them, 2289, Renton University Press:

 

MG David Mcneil, CRA (Ret). Chief of CRA Armored Force from 2278 to 2282, MG Mcneil was the only Chief of the Armored Force to have begun his military career as an enlisted soldier. He also was a member of the 1st Sqdn (Tank), 1st Armored Brigade’s “First Class”, the first tank unit to be transitioned to the Medium Tank M4. Known for his highly aggressive leadership style and personal bravery, Mcneil has the dubious distinction of having bailed out of a Medium M4 from every hatch and every crew position. He has 38.875 tank kills and a further 47 probable kills, and has received eight Purple Heart medals. A renowned polymath, Mcneil holds advanced degrees in mechanical engineering and history, and currently splits his time between teaching military science at the Cascadian Military Academy and consulting with several defense contractors.

 

On first encountering the Medium M4:

Up until that point, we had been using the Medium M3, a fairly serviceable, if dated design by the late ‘30s. At that point, I was a fresh-faced nineteen year old private first-class, and while we knew our M3s weren’t quite the firebreathing impenetrable powerhouses that some of the more sensational papers made them out to be, we were damn proud of them and we thought they were pretty hot stuff. I remember the day that we were first introduced to the Medium M4. Our Squadron was loaded into a convoy of deuce-and-a-halfs and we were driven to the Renton Locomotive plant. Once we got there and had been shepherded to a set of bleachers outside this big field, our CO, Mike Anderson, a man who I then hated but would come to respect more than anyone except perhaps God and my mother, stood in front of us, and explained why we were there -- the Government had decided we were to get a new tank, they’d bought one, and they had chosen us to be the lab-rats for the field trials and IOC. He then called us to attention, turned on his heel, and waved to a guy by the corner of a nearby building, and we heard it for the first time. We all knew what a tank starting up sounded like -- you had the whine of the solenoid, the coughing and then roar of the engine as it spun and caught, and then a rumble as it settled down to idle. This was different -- all we heard was a quiet whine, which built to a sort of whistle. Of course, we’d all heard about jet engines, and seen video of the old pre-war Abrams, and some of us even read Aviation Week and knew that PacAero was working on turboprop and turbojet aircraft, but we figured that a tank turbine was a technical impossibility in the late 2230s.

 

The first thing we saw was the gun, which is one of the better ways to spot an M4 Medium. The damn thing is so long that it’s hard not to miss it, but we saw this gigantic barrel coming around the corner and one of my very good friends, Tony Anglio, whispered to me something like “This has to be some kind of joke, that gun’s bigger than our friggin tank!”. Then, the hull just sort-of floated into view. The double-acting torsion bars and massive shock absorbers on the M4 gave it a very distinctly floaty ride, since they were designed for a substantially heavier vehicle than the already-heavy M4. The thing that really struck all of us, I think, was how quiet the damn thing was, despite its large size. That said, the M4 was just a mean looking bastard. The M3 Medium was almost cute in its very traditional construction, and well-proportioned lines, while the M4 looked strange in comparison. We wouldn’t find out until later exactly why it had all the tiles and the fairly flat armor, at the time we figured it was steel, and a lot of it.

 

The M4 was always full of surprises. Once we saw it and got used to the sound, we figured, well, okay, it’s going to be pretty slow -- it’s got all that thick armor and that great big gun, and it’s fairly small. As if on cue, when it got right in front of the bleachers, the driver hit the gas and the damn thing took off! We would come to appreciate the amount of time and effort the Renton boys had put into the vehicle, and the lengths they had taken to finally give Cascadian tankers a technological edge over our Californian enemies.

 

On actually fighting the M4 Medium

 

The thing to keep in mind about the M4 -- and I mean the M4, not the M4A1 or A2, because each of those was almost a different tank in how heavily they upgraded them -- is that even for all its advancements, it was still a product of the era. Yes, it had a very advanced gun-laying system and two-axis stabilization, but they were fairly slow, and a lot of the better gunners got very adept at using the reticle to range the target. The automatic rangefinder still took a good four seconds of steadily tracking a target with an unbroken sight picture, not an easy feat in combat, and the mechanism really wasn’t technically mature, but it worked enough of the time to be a suitable stand-in for the laser rangefinders that replaced it. Oh, and the damn thing would stop working whenever the Contact explosive reactive armor tiles near the rangefinder blisters went off -- half the time we either took them off or replaced them with a chunk of solid steel, just so that we didn’t have to recalibrate the rangefinder. They never really fixed that, either.

 

At first, the M4 had hands-down the best armor in the world -- unsurprising, since it was more or less an unabashed copy of the HAP-1 package off the Prewar M1A1HA Abrams. It was easy to get lulled into a false sense of security by the ERA and the composite armor, and forget that the thickest the hull got was only three inches. It was quite common for the detonation of the ERA tiles to dent and bend the ¾” outer shell of the tank, especially the RAT tiles on the bow -- when they went off, it was something like 16 pounds of Composition B throwing a 12-pound steel plate into the hull.

 

On the Battle of Yreka, the combat debut of the M4 Medium

 

The gun and mobility on the M4 were exemplary. When we first hit the battlefield it gave those Calif[ornian]s a shock, let me tell you. I remember the first combat action we took. We were dug in on a ridgeline, had a line of sight out, damn must have been four kilometers or more. We’d just had our breakfast and buttoned up when they hit us. That was the first time I’d been under the “VT” shells. Proximity fuse, you see. All the fun of tree bursts without the trees. Then they laid in smoke. So thick you couldn’t hardly see the end of the gun barrel out the periscope. Played hell with the automatic rangefinders, not that they worked much anyway. Somehow we made it work. With a battalion of Califoria’s finest coming at a company of Cascadian Regulars, there’s not much of a choice anyhow. We held fire on ell-tee’s orders until a thousand meters. Then the whole platoon let go in one volley. They must have thought the gates of hell opened on ‘em or something. They had us three-to-one, but our position, armor and gun made it closer to even money. All I remember is Charlie, the TC, his fire commands. ‘Gunner tank 800 meters front AP fire’ then ‘Identified on the way’ and then ‘gunner new target 750m front’ and so on like that. I was in my own little world, y’know? I think we got four or five that day. And I thought to myself, this is it, the perfect tank.

 

 

1. LCOL Mark Ishmael Karol Edward Anderson was killed in action in March, 2243 defending Klamath Falls. He was posthumously awarded the Washington Cross with Valor Device for his actions.

2. SSgt. Tony Anglio, CRA (Ret.) served with distinction against both Mormon and Californian forces from the mid-2230s into the 2250s. He retired in 2265 after 24 years of service, primarily in the Armored Force.

3. The M4A1 incorporated an improved engine, revised and upgraded armor packages, and a refined, 55-caliber gun. The M4A2, the “Digital Four” (earning crude nicknames like Fister and Shocker), incorporated a fully electronic fire control computer and a laser rangefinder, new stabilizers, even heavier armor, electro-optical sighting systems, a new gas turbine and transmission, thermal imagers, and a version of the pre-war Watervliet M256 120mm 44-caliber gun. The current M4A3 brings the tank to its fourth gun, the M360A1 120mm 52-caliber smoothbore, it’s third engine, sixth armor package, and incorporates an active protection system and greatly improved laser rangefinder.

4. B Coy, 1/1 Tanks dug in on the ridgeline between old CA route 263 and US I-5 about two miles north of Yreka, CA on the night of March 22, 2240. A Coy. was arrayed to the north, slightly further up I-5, and C Coy. and the Dragoon Battalion of 1st Tanks occupied Yreka itself, with B-1/1 and 2bn of the 4th (Olympia) Infantry Bde. preparing for an assault on Siskiyou County Airport the next morning. Shortly before the jump-off time, the Californian 1st Battalion, 3rd Guards Heavy Tank Regiment, of the elite 8th Guards Shock Air Force Parachute-Tank Division Kamala Harris (An homage to a semi-mythological early 21st century politician revered by the Californians) launched a spoiling attack consisting of eighty two Mark Six heavy tanks and fifty two half-track infantry carriers, supported by significant tube artillery. This represented ten percent of the Californian inventory of Mark Six heavy tanks at the time. In a battle that firmly established the fearsome reputation of both LCol. M.I.K.E. Anderson and the M4 Medium, as well as the extreme ideological indoctrination of the Communist Guards-divisions, B Coy, 1/1 Tanks blunted and stopped the Californian attack, then began a vicious counterattack that included LCol. Anderson’s tank being disabled by infantry attack whilst he lead a headlong pursuit of the retreating enemy, after which he is rumored to have fought off an element of the Communist forces with a pistol and saber.

5. MG Charles M. Dietz, CRA (Ret) was one of three crewman in Barely Legal (M4 S/N 10052, now preserved at the Cascadian Military Museum, Renton) who attained the rank of Major General (including MG McNeil and MG Dana R. Carter, CRA (Ret). The loader, Sergei I. Danilov, reached the rank of Colonel before his death at the hands of Deseret agents during his tenure as commander, 4th Armored Cavalry Bde. He was killed during a running gunbattle in the streets of Pocatello, Idaho Territory, in 2265. His assassination was a great loss, as he was working on writing an operational maneuver doctrine based on pre-war Soviet and American work.

[Jeeps_Guns_Tanks]

The Judges are now reviewing the entries. 

[LoooSeR]

@A. T. Mahan

Judges would like to know more on proposed light tank main weapon feed system. How it loads/reloads, how ammunition loading/handling is happening in it, etc. 

[A. T. Mahan]

@LoooSeR

 

The autoloader mechanism is a slightly resized version of the aircraft mounted version of the Molins Auto Loader Mark III. The only noteworthy changes were a slight lengthening of the magazine and action to accommodate the 57x480mm cartridge, from the original 57x441mm cartridge. It operates most similarly to a long recoil small arm, with the semiautomatic vertically sliding breechblock falling at the rearmost extent of the recoil stroke, with ejection of the spent case occurring during counterrecoil. The new cartridge is fed into the action by a springloaded arm tripped by the passage of the breech near the end of the of the counterrecoil stroke, and the breechblock is actuated by the rim of the cartridge when the case is fully seated. Upon firing, the loading arm is recocked by the force of the recoil stroke, and the cycle begins again. 

 

The loading arm is visible in an intermediate position on this QF 6pdr Type M Mark I with Auto Loader Mark III

 

Initial loading is accomplished by either manually cocking the loading arm, opening the breech, and inserting a case as in a manually loaded gun, or by cocking the loading arm, opening the breech, and actuating the loading sear override handle, which triggers the loading arm. 

 

The magazine is loaded manually, one round at a time, by inserting the nose of the projectile and rim of the cartridge case into their respective feedways in the magazine. 

 

The ammunition feedways in the magazine are visible in this image of a 6pdr Type M Mark I with Auto Loader Mark III on a test mount

Loading is primarily intended to be accomplished by the commander, as the 24-round magazine provides substantial capacity compared to, for example, the eight rounds of the Bofors 40mm automatic guns or the 16 rounds of the 57mm AZP S-60. Furthermore, as the gun is primarily intended for use against armored ground targets and has a relatively mediocre HE shell due to the very high muzzle velocity and thus thick shell walls, ammunition expenditure should be comparatively limited. It is also worth considering that the gun will likely not be fired in bursts, but in semiautomatic fire, where the automatic loader and 24 round magazine would reduce engagement times dramatically when compared to, for example, a manually loaded gun of similar performance.

[Sturgeon]

Speaking of autoloaders, something I forgot to detail in the post was the autoloader scheme for the M13A4 Sandy. It's similar to but slightly different than the one used in the T22E1:

 

 

Unlike the T22E1, the M13A4 has only -5 depression, so the loader itself does not need to come up as high as depicted for the T22E1 which IIRC has -12 depression. There might need to be a slight hump added to the gun box to accommodate it, but nothing major. The Sandy didn't receive as much attention to detail as the Donward or Roach because I had to wrap it up in a rush.

 

The ammo box and transfer mechanism I envisioned were slightly different, though. I'm not at home right now so I can't check, but IIRC the ammunition stowage for the Sandy lives in a box to the right of the driver. The transfer mechanism consists of a claw which can grab the rims of rounds and pull them out onto a tray, which then presents the rounds to the autoloader. If I'm remembering right, I intended for the transfer mechanism to live in the hull (it would be located below the crew's feet), and handoff of the shell would occur at the rotational axis of the turret.

[LoooSeR]

@N-L-M

1. I can't find a definitive number of people in a crew for Norman. It is kind of important, as this characteristic is in basic requirements.
2. Red Fox submission doesn't have anything about engine used in mobility section and also lacks crew composition data.
3. Red Fox driver placement is not visible and i didn't saw anything on how he get in/out.

 

 

 

[N-L-M]

1. 4 crew: driver in hull front, commander under cupola, gunner in front of commander, loader on the left of the turret.

2. The engine is something like Detroit Diesel 6V53T, roughly 250-275 horespower diesel. 3 crew: Gunner to the left of the turret, commander to the right, driver in center front hull.

3. The driver's hatch and periscopes were not modelled, but a hatch somewhat like that of the Fox armored car was envisioned:

The swinging axis allows a fairly heavy (well armored) hatch with good access and good visibility open.

The hatch has the ability to fit IR periscopes.