FINAL SUBMISSION: XM-2239 NORMAN
[ooc: this is written from a timeframe at which only a few prototypes have been built and tested, mass production awaits selection. Square brackets denote ooc comments]
Classified: top secret
for Cascadian eyes only
When General Foundry and Mechanics (henceforth, GF&M) received the brief from the Cascadian armored corps on the requirements for a future armored fighting direct combat vehicle, medium (henceforth, medium tank), and future armored fighting direct combat vehicle, light (light tank), focus was immediately concentrated on the larger requirement of the pair. It was quickly realized that the requirements fell significantly short of the state of the art; and that said state of the art permits the development of a vehicle not only superior to the requirements in every regard, but capable of matching the requirements of the future as well, thus ensuring the safety and freedom of Cascadia for generations to come.
Intelligence gathered from neighbouring states set the basic offensive and defensive requirements; the larger mechanized and armored forces of California to the south, and the more mobile and dynamic, but lighter, forces of Deseret to the south-east. Protection requirements for the medium tank were set by existing and projected future enemy weapons, as detailed in report (REDACTED).
Likewise, the performance characteristics of the main armament were set by the current and projected protection of vehicles in the possession of the neighbouring states, as detailed in report (REDACTED).
Upon receipt of the above reports and requirements, GF&M’s Archival Division in conjunction with the engineering divisions (Mechanical, Electric, Aeronautic, Automotive, and Ballistic) conducted a survey of the current engineering state of the art, in particular with regard to the ability to construct large complex assemblies to an exacting standard. From this survey, it was determined that the current industrial base is roughly the equivalent of that available in Tank City, Michigan, circa 1950. Likewise it was determined that the state of the art from an electronics standpoint is roughly equivalent to that available in the same time period. Theoretical knowledge available, however, significantly exceeded that level; the divisional chief engineers all have archival clearance and are well-educated on the finer details of the achievements in their respective fields all the way up to the Ultimate War. While the state of the art does not support the immediate manufacture of prewar equipment, many lessons were learned in the past through trial and error, which is estimated to have saved years and many cycles of iterative design and testing in the development of the medium tank.
Following the industrial survey, the archival division conducted another study; this one historical, examining the vehicles produced pre-war with similar industrial capabilities, as well as the evolution of design from that point to the onset of the War. Individual designs were examined based on archival evidence throughout their lifetimes, noting their technical-tactical characteristics as well as more subjective factors such as efficiency of design and manufacture, maintainability, upgradeability, crew comfort, battle efficiency and so on.
Following this survey, it was found that the pre-war Soviet tank T-55 is well within the capability of the industry to construct, and other than minor dimensioning issues more than outmatches the required specifications. While this design had many flaws, and by design was not optimized for the nature of the Cascadian environment, it was chosen as a baseline as it was evaluated to offer more potential than the other possible baselines (Centurion, M-48 Patton), mostly due to small dimensions, reputation of maintainability and reliability, and efficient layout.
From this baseline, a series of improvements were suggested by the Archival Division to the engineering divisions, to better suit the medium tank to the Cascadian environment, as well as to apply the lessons learned throughout the service lives of the vehicles studied.
The list of suggested improvements was as follows:
1. More compact, autofrettaged gun of ~4” calibre.
2. Crew water stowage.
3. Increased crew working volume. Specifically, improved head space for loader.
4. Improved gunnery optics (including the installation of a rangefinder).
5. 8-10 degrees of gun depression.
6. APU of roughly 1-2 cylinders (2-4 HP)
7. Basic air conditioning
8. Spaced armor arrays
9. Reversed turret crew (gunner and commander on right, loader on left
10. More, better accessible, ready ammunition racks. In the bustle with blowoff panels, if possible.
11. Improved hatches (sprung) and access.
12. Desertised larger air intakes and filters.
13. External coil spring suspension, with return rollers.
14. Improved protected external stowage.
15. 2-channel gunner’s sight, with periscopic mirror head.
16. 2-axis stabilizers, with the gunner’s line of sight being stabilized independently of the main gun, with the gun following the sight, to allow accurate observation and quick firing from the short halt, as well as the use of the coaxial MG on the move. Such a system also allows the implementation of fixed-angle loading, easing the loader’s work without affecting the gunner’s observation of the target.
17. Separated hydraulics, in the turret bustle.
18. Commander’s MG useable under armor.
19. Infantry telephone in rear sponson.
20. Ammunition loading hatch near ground level.
21. Automatic fire suppression.
22. Over-barrel fitting for either spotlight (white light or IR) or .50 BMG.
23. Thicker front hull for mine resistance.
24. Roof machine gun for both loader and commander.
25. Frontally removable gun, with separately removable barrel, for faster and simpler field maintenance of the weapon system and to allow easier modification and upgrading of the vehicle throughout its service life.
26. Making the Commander’s cupola a hunter-killer system. This involves the use of an independently driven cupola, with independently stabilized optic, and slew-to-cue control of the turret, allowing the commander to find, range, and pass over targets to the gunner, greatly increasing the battle efficiency of the vehicle.
27. Fitting of indirect fire equipment. As the gun on the tank is liable to be one of the larger guns available in any given setting, the ability to conduct indirect fire when possible is considered to be a great advantage.
28. Boiling Vessel, allowing the crew to heat their food and that of any infantrymen, boosting morale and reducing fatigue.
29. Ammunition load of roughly 40-50 rounds for the main gun, and roughly 5,000 rounds of secondary ammunition
30. Improved suspension damping and increased wheel travel.
31. 6 wheel stations per side
32. Volume allocation for more advanced electronics, including but not limited to image intensifiers, ballistic computers, and so on.
33. Improved transmission, with emphasis on reverse speed.
34. Fittings for tank riders, should doctrine require.
35. Design for upgradeability, particularly with regard to electronics and armor technology.
36. Drive system packaged as powerpack to allow easier repair and maintenance.
With the above list of changes, the resulting vehicle bears only a mild resemblance to the venerable T-55 upon which it is based, and yet maintains many of the classic features which made its forbearer a success.
The resulting vehicle entered iterative development and prototyping; In the basic stages of which it was found that all the desired improvements could not only be fulfilled, but even exceeded; The resulting vehicle has greatly improved protection in the frontal 40 degree arc for the hull and 60 degree arc for the turret, along with having all the main gun ammunition safely stowed in separated compartments with blow-off panels, keeping the crew safe. The greater weight of the vehicle compared to the T-55 is compensated by use of a more powerful engine of similar size, a more advanced transmission, and longer track contact along with more wheels, reducing the mean maximum pressure.
Despite HVAP being the standard AP ammo, it was decided not to optimize the gun around that ammo type, as very soon APDS and APFSDS will be available, and will completely eclipse HVAP.
The features of the vehicle are as follows:
1. 600HP (750HP with supercharger) V-12 diesel engine [T-55 engine, uprated to the historical KV levels, with supercharger it’s at T-72 levels]
2. Mechanical-Hydraulic cross-drive 12 speed transmission, 6 forwards, 6 reverse, with good mountain fighting ability [Stolen off of a Pz 61]
3. 1500L diesel fuel, stowed outside crew compartment
4. 4 HP APU exhaust acts as engine compartment heater in cold weather.
5. Small air compressor fitted to engine and compressed air tank allow starting in extreme weather without batteries, along with easy cleaning of the air filters at routine intervals.
6. Enlarged engine bay relative to T-55, to house larger radiators and fans, improving cooling capacity in desert environments. Air is exhausted downwards behind the vehicle, M60 style, to avoid the “rooster tail” effect of the original T-55.
7. Rotary dampers on each swing arm hub and linear dampers on first, second and last swing arms.
8. Vertical travel of roughly 400mm up, 150mm rebound
9. Ground clearance of 540mm
Low profile- 2.32m turret roof height, 2.66m top of commander’s sight, extremely low profile in hull-down positions.
Frontal arc - no less than 200mm LOS base steel* with air gap and another 60mm LOS spaced hard steel layer, or angles exceeding 80 degrees from normal.
Lower glacis- 30mm hard face, 500mm fuel tank, 50mm back face at 20 degrees from normal.
Sides- crew compartment armor at least 40mm LOS with 20mm high-hardness plate welded on hull, 100mm on turret, with spaced 30mm,
Non-crew compartment-40mm side armor. 20-5mm spaced skirts on hull. Sponson boxes- 30mm armor on frontal boxes, 10mm on rear boxes.
All-around armor- no less than 30mm steel for direct and air fire, 30mm front floor, 20mm rear floor.
Mounting points for explosive reactive armor are available on the external faces of the spaced armor arrays.**
All ammunition separated from the crew behind blow-out panels.
Instantaneous (WP) smoke grenade launchers- 24 ready, 24 stowed. (4+4 salvos of 6) [launchers on the turret flanks, not modelled]
Automatic IR-detection fire suppression system in crew and engine compartment.
While not fitted as standard, the crew compartment is spacious enough to allow the fitting of spall liners when the technology to make them reliable and not a fire hazard is around.
*The base steel is not homogenous; on the turret cheeks and sides, and on the hull front, it is an arrangement that can only adequately be described as “inverse Stillbrew”. The armor comprises a 50mm thick base layer, with the secondary casting bolted on with a rubber interlayer in the middle. The purpose of this arrangement is not to increase protection (although it should a bit), but rather to aid upgradeability- when better armor gets developed, it is intended that the thick steel facing plates be swapped for more weight-efficient armor. The volume needed for these arrays is already available, as the spaces of the spaced armor. The stowed equipment in those pockets will be displaced to less critical locations.
**It is intended that with the steel armor replaced by NERA arrays and the external face topped with ERA, that the total armor array will be ERA-hard armor-NERA-backing steel armor.
Such an array is reminiscent of the T-72BV turret and could quite reasonably be expected to handle tandem HEAT and moderately advanced APFSDS constructions. This drastic improvement in protection could easily be a simple part of a midlife upgrade, with the chosen construction methods.
1. Dual stabilized (sight following) 105mm L/51 autofrettaged gun with brass cases, fitted with fume extractor and thermal shroud. [basically an M68 with a slightly larger case].
APCBC [BR-412D with slightly higher velocity]
Smoke-WP [unless it really doesn’t work with horizontal stowage]
HVAP [T29E3 at lower velocity than from the gun T5E1]
Stowed ammo: 56 rounds, of which 16 ready in bustle; the rest behind blast doors and equipped with blowoff panels in the hull.
2. Upgradeable to 125mm L/45 gun, when available, intended to use combustible-body stub cases [basically slightly larger NATO 120, there’s room in the turret but the gun isn’t industrially feasible yet]
Stowed ammo: ~42-45, of which ~10 ready in bustle; the rest behind blast doors and equipped with blowoff panels in the hull.
3. 1 coax M240 Stowed ammo: 6,000 rounds, of which 2000 ready.
4. 1 M240 on commander’s cupola, fireable under armor.
Stowed ammo: 2400, of which 600 ready.
5. 1 M240 on skate mount [modelled as pintle] for loader.
Stowed ammo: 2000, of which 200 ready.
6. 1 M2 HMG over barrel (optional)
Stowed ammo: 1300, of which 100 ready.
1. Dual-channel 2-axis independently stabilized gunner’s sight with extension for commander.
2. Gunner’s secondary direct-vision telescopic sight.
3. Commander’s fire control cupola: single-channel (selectable) main independently stabilized optic, with secondary coincidence rangefinder channel. 5 periscopes allow all-around vision, slew-to-cue feature.
4. 3 periscopes for loader improve situational awareness.
5. Commander’s hatch with open protected position in development.
1. Range-finding stadiametric reticles.
2. ballistic cam computer with automatic feed in from commander’s rangefinder, automatic superelevation.
3. Gun follows sight (with offset based on superelevation from ballistic computer)
4. Hydraulic control- 15 deg/sec elevation, 40 deg/sec traverse (basic turret), 30 deg/sec (fully up-armored). Pump, accumulator and reservoir are separated from the crew, in the bustle, and the system is fitted with a pressure-loss automatic cutoff to prevent the hydraulic fluid spraying everywhere in case of a rupture.
5. Commander has override handles.
For the external machine guns, spare ammunition is carried in belt boxes in the spaced armor of the turret. 12 boxes of .50 can be carried in the frontal pockets, with 100 rounds linked each; and 9 7.62 boxes in each side of the turret, with 200 rounds linked each. The commander’s cupola has a 600-round ring ammo box around the cupola [not modelled].
1. Air conditioning. Operating armored vehicles in the desert without this feature is torture, to say the least. In the bustle, between the hydraulic unit and the ammo rack, sits a powerful air conditioning unit. Rated at 3 HP, this is enough to properly cool down the fighting compartment even with moderate air leakage. While currently no requirement for NBC exists, such an air filtration system could be merged into the aircon unit. When firing, the blower fan is directed into the fighting compartment and not the aircon radiator, to clear out the gasses.
Aircon also aids in maintaining the life of electronic components, an important feature for such an electronically-rich vehicle.
With flow reversal, the aircon unit heats the crew compartment during the winter, with none of the dangers of a fuel-powered crew heater.
2. Drinking water. There is a tank for drinking water installed, aft of the turret. With a capacity of 240 litres, this allows the tank to operate in the desert and support infantry for extended operations without supply. Additional external stowage is of course possible. A small water container sits directly in front of the aircon vents, allowing the crew to drink at a comfortable temperature. (The main water tank sits up against the engine firewall and will likely get a bit too hot for comfort.)
3. Boiling Vessel. Allows cooking MREs for the crew and infantry, and hot drinks during the winter.
4. Height. All seats are adjustable and suitable to the above-average Cascadian recruit. The loader’s position is arranged in such a way that most of his duties can be performed sitting down. There is sufficient headroom and elbow space in every crew position, and using the equipment requires no contortionisms.
5. Ammo loading hatch- allows loading ammo into the tank from ground level, and not from roof hatches, results in less tiring and quicker loading.
6. Fume extractor on the barrel greatly reduces the flow of gas into the fighting compartment when the gun fires.
1. Overbuilt, easily upgradeable suspension. Allows weight growth, at cost of increasing ground pressure.
2. Armor upgradeability, as explained in armor section. Current armor is fairly inexpensive, and allows inexpensive upgrading at a later date, allowing fairly cheap buildup of forces and allows use of more mature armor when the upgrade occurs (as current reactive armor arrays developed at GF&M are fairly crude). Current armor more than outmatches current and projected enemy weapons.
3. Powerpack dimensions, and those of engine bay, allow upgrading with bigger and better powerplants and transmissions as they come available. The engine bay is 200mm longer and 200mm taller (at the hump) than that of the T-55, to allow better cooling and more upgradeability. It is expected that upgrade powerpacks with 1000HP transversely mounted engines with automatic transmissions, as were available pre-war for the T-72, will be possible for a late-life upgrade.
4. Spare internal volume for more vetronics.
5. Frontally removable gun, allows easy maintenance and upgrading.
6. Configurable ammo racks inside blowoff bunkers allows depot-level reconfiguring for different calibres.
Vents were not modelled due to lack of time.
Turret structure: 6.0 tons, includes internal subdivisions and basket
Turret spaced: 1.8 tons, includes partitions
Hull structure: 13.8 tons, includes suspension mounting points and internal subdivisions.
Hull spaced: 1.92 tons, includes sponson stowage boxes.
Suspension: 4 tons.
Tracks: 3.3 tons, based on T-72 track links.
Armament: 1.3 tons
Ammo: 1.5 tons
Fuel: 1500L, 1.23 tons.
Engine, cooling and accessories: 1.5 tons
Transmission: 2 tons
Extras: 6 tons, includes 0.5 tons electric systems, 0.5 hydraulics, 0.3 tons water, 1 ton structural components, 0.3 tons for the aircon system, 0.5 tons for fittings, 0.4 tons of crew, and a margin of 2.3 tons for things unaccounted for.
Total, loaded: 44.3 tons.
Length, gun forwards: 8.7m
Length, hull: 6.3m
Width, OA: 3.3m
Width over tracks: 3.24m
Ground clearance: 540mm
Height, turret roof: 2.33m
Height, overall: 2.66m
Idler height: 0.84m (relevant for vertical step climbing)
Track contact length, zero penetration: 4.38m
Track width: 550mm
Roadwheel diameter: 686mm
1. The gun uses brass-cased ammo as semi-combustible case tech does not seem to be ready for prime-time with 1950 tech, as evidenced by the problems with the ammunition of the US 152mm gun on the M60A2 and Sheridan in the 1960s; The combination of good rigidity needed to hold large propellant loads onto big heavy projectiles (like 105mm APCBC) and good burn characteristics would seem to be beyond current tech, and therefore extremely risky to develop.
2. As brass-cased ammunition was chosen, 105mm was the logical caliber to use, as it is the largest caliber which can still be relatively easily man-handled in the confines of a turret, when brass cased full-bore AP rounds are used.
3. The future 125mm intended for the mid-life upgrade is intended to be stub-cased combustible, smoothbore, with APFSDS as the primary anti-armor round. It is expected that by the time the gun is ready and needed, the technology will have progressed sufficiently to allow higher pressures and reliable strong combustible case bodies. As the ammo stowage is already compartmentalized, this ammunition will pose no greater risk to the crew.
4. The tank, with its current weight, is train-deployable fully loaded. The weight margins ensure that when upgraded it will still be transportable in MLC-45, without loaded ammunition, fuel, crew, and other extras.
5. Current development of variants includes:
a. CEV (similar in concept to M728 CEV, with 155mm demolition gun/low velocity howitzer)
b. Bridgelayer (Similar in concept to M60 AVLB, with bridge designed for MLC 70-80)
c. ARV (similar in concept to M88 ARV, with a crane)
d. HAPC/HIFV (similar in concept to Achzarit with small cannon/MG turret, axial instead of transverse engine)
e. SPAA (Shilka-like turret, with twin 35mm guns, and basic air search and ranging radars; plenty of space for more advanced electronics when available)
6. The compressed air starting system connects to a pneumatic joint in the engine bay, to which air-powered tools can be attached. Current supplied tools as basic vehicle equipment include a pressure blower for cleaning air filters and the like, a pneumatic bolt-driver, a pneumatic jack, and other assorted goodies.
7. A coincidence rangefinder was chosen, as no low-risk practical alternative could be thought up. It is intended to be replaced as soon as possible with a laser rangefinder, and an additional laser rangefinder to be installed in the gunner's FCS suite. A coincidence rangefinder takes around 10-12 seconds to range effectively; with the rangefinder in a separate mount, the commander can range a target while the gunner engages a different one, allowing high-speed hunter-killer operation.