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1 hour ago, Sturgeon said:

I'm pretty impressed by that, @Toxn.

 

Small suggestion: Give the turret an undercut and/or some additional curvature, and move it up a bit. If you have a pop-up-swing-out driver's hatch, should save you some hull volume.

I'm probably going to curve it a bit more if I decide to go for a cast-only version of the turret (the current one can be either welded or cast) but I think that options for undercuts will be limited.

It's only going to save something like 25cm anyway, so I'm not too worried.

 

Edit: rounding the turret and making a small undercut saved 10cm. It looks prettier, though.

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46 minutes ago, Toxn said:

@LostCosmonaut Quick formalities question:

 

Should I edit my original post to finalise it, or make a new post and mark it as finalised? 

 

Whichever one is easier for you is fine. I'd like it if you left your old designs up somewhere, though (been interesting to see the evolution of the concepts).

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(hopefully) FINALISED ENTRY

 

XM8 “Elk”

YFGNamZ.jpg

General

 

Dimensions:

  • Length: 6.40m (hull) 8.00m or 9.25m (gun forward)
  • Width: 1.90m (hull), 3.18m (total)
  • Height: 1.15m (crew compartment), 1.30 (engine compartment), 0.75 (turret) 2.70m (total)
  • Ground clearance: 0.47m

Weight:

  • Light: 25t combat weight
  • Medium: 44 t combat weight

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

 

Defensive

 

Armour (light):

  • 145mm aluminium @ 45’ (upper hull front)
  • 70mm aluminium @ 45’ (lower hull front)
  • 65mm aluminium (hull side forward)
  • 25mm aluminium (hull side rear)
  • 25mm aluminium (hull rear)
  • 25mm aluminium (hull roof)
  • 25mm aluminium (hull floor)
  • 175mm aluminium @ 30’ (turret front)
  • 65mm aluminium (turret side forward)
  • 65mm aluminium (turret side rear)
  • 25mm aluminium (turret rear)
  • 200mm aluminium (mantlet)
  • 35mm aluminium @ 80’ (turret roof forward)
  • 25mm aluminium (turret roof rear)

 

Armour (medium):

  • 145mm RHA @ 45’ (upper hull front)
  • 70mm RHA @ 45’ (lower hull front)
  • 65mm RHA (hull side forward)
  • 25mm RHA (hull side rear)
  • 25mm RHA (hull rear)
  • 25mm RHA (hull roof)
  • 25mm RHA (hull floor)
  • 175mm CHA @ 30’ (turret front)
  • 65mm CHA (turret side forward)
  • 65mm CHA (turret side rear)
  • 25mm CHA (turret rear)
  • 200mm RHA (mantlet)
  • 35mm CHA @ 80’ (turret roof forward)
  • 25mm CHA (turret roof rear)

 

Weapons (light)

 

80mm L/55 cannon:

  • AP: 8.4kg @ 955m/s, ~180mm @ 500m
  • APCR: 4.7kg @ 1280m/s, ~240mm @ 500m
  • HE: 7.5kg @ 700m/s
  • ME: 3.85MJ
  • Vertical movement: -12’/+35’

 

Browning M2 machinegun (turret roof)

 

M240 machinegun (coaxial)

 

Weapons (medium)

 

105mm L/52 cannon:

  • AP: 17kg @ 900m/s, ~200mm @ 500m
  • APCR: 10kg @ 1230m/s, ~290mm @ 500m
  • HE: 15.1kg @ 700m/s
  • ME: 7.6MJ
  • Vertical movement: -10’/+20’

 

Browning M2 machinegun (turret roof)

 

M240 machinegun (coaxial)

 

Automotive

 

Engine :

  • Light: 18L, 450 HP (340 kW) V8 petrol engine (Ford GAA derivative)
  • Medium: 29L, 750 HP (559 kW) V12 diesel engine (Continental AVDS-1790 derivative)
  • Internal fuel tanks: 700l stored on either side of driver + 450l stored in rear of hull compartment on either side of turret basket.

Power/weight:

  • Light:18 kW/t
  • Medium: 17 kW/t

Max speed:

  • 70 km/h (road)
  • 35 km/h (offroad)

Range:

  • Light: 1050km (road)
  • Medium: 450km (road)

 

jG9KgPA.jpg

Description

 

The XM8 “Elk” was the result of a proactive, iterative design process, intended to provide a ‘universal’ tank optimised for fighting a defensive war against Californian forces and serving in a more mobile role in the Oregon/Idaho sector. The design is also intended to have reserve capacity for upgrades as they become available.

 

The core of the vehicle is a simple hull with a clean, sloped front and a large engine bay in the rear separated from the crew compartment by a 25mm armoured bulkhead. The armour layout emphasises frontal engagements and crew protection, with the forward side armour (covering the crew compartment) being significantly thicker than the rear side armour. The primary fuel cells are placed in the front hull to either side of the driver to improve protection against HEAT weapons and mitigate spall. secondary fuel cells are placed to the rear sides of the turret basket.

 

The XM8 is offered in two variants: a 44t ‘medium’ version and a 25t ‘light’ version. The medium version is designed to resist current-generation heavy anti-tank weapons across the hull front and turret frontal arc from any distance, with current generation medium anti-tank weapons being resisted across a 45 degree arc covering the crew compartment. The medium is expected to remain well protected against medium anti-tank weapons for the foreseeable future, and is expected to resist heavy anti-tank weapons across the hull front and turret front at ranges beyond 1000m.

 

The light version achieves its lower mass by being made entirely from aluminium and having a lighter engine, transmission and suspension package. The aluminium armour is significantly less protective than steel, but still provides approximately 85mm of LOS RHA equivalence (and around 140mm of LOS HEAT protection) across the upper hull and turret front. Having sacrificed protection, the light variant does gain significantly better flotation and strategic mobility. Use of light tank hulls and turrets fitted with medium components would also allow a 'blended' XM8 to fit up to 14 extra tonnes of extra armour and equipment without needing to upgrade the suspension or transmission elements. This crossover capability is expected to be useful if shaped charge weapon systems become predominant on the battlefield.

 

The engine bay is designed to facilitate service and repair, and has large rear doors for access to the engine and transmission. The engine and transmission, in turn, are mounted using a rail system so that they can be easily pulled. The radiators and fans are mounted in hinged doors on the hull roof, which also double as access points for service. The emphasis on ease of maintenance continues to the suspension system, which is an external torsion bar system. The vehicle has a respectable level of ground clearance.

 

qDWzvHC.jpg

 

The cast turret is roomy thanks to a large 1.9m turret ring, which is also expected to facilitate upgrade programs going forwards. The turret is six-sided, somewhat sloped, and contains generously-sized hatches for the crew. The turret is equipped with a skeletonised basket incorporating large openings for accessing ammunition storage in the hull. The commander’s hatch is equipped with multiple vision blocks to provide good visibility while buttoned up. The commander and loader also have access to rotating periscopes (based on the M10 design) for the purposes of target acquisition. These periscopes have azimuth indicators for directing the gunner. The gunner, in turn,  has access to an azimuth indicator mounted to the turret ring, periscope and telescopic sight (based on the M70 series) for target acquisition and lay-in. The periscope is selectable for 1X, 3X and 6X magnification. The sight has various reticles for the main ammunition types. A gunner’s quadrant is provided for ranged fire missions. Range finding is done using the stadiametric approach with coincidence and, eventually, laser rangefinders being envisioned as future upgrades.

 

The gun is vertically stabilized, allowing for more accurate snap shooting at low speeds and (more importantly) quicker shots after a short stop. Two and three-axis stabilisation are expected to form part of future upgrades.

 

The rear of the turret houses the radio set – a new transistor design based on the pre-war SCR-500 series. This set includes an intercom system, and is expected to be less maintenance-intensive than our existing sets. The rear hull side contains a small telephone, linked to the intercom system, to allow infantry to communicate with the crew.

 

The turret drive is electric, and manages a full rotation in around 15 seconds. The electric unit does not allow for very precise movement of the turret at present, so the gunner’s hand wheel is necessary for fine adjustment. Future hydraulic or electric drive systems are expected to overcome this issue.

 

The 80mm main gun used on the light version of the XM8 is a high-velocity piece able to penetrate any commonly-encountered armoured vehicle from the front at combat ranges using the present AP and APCR shells. The gun also sports a very good HE shell, which is fired using a lower-velocity charge. The 80mm is expected to remain viable against most light and medium vehicles for the foreseeable future using existing ammunition, with the development of APDS and APFSDS ammunition expected to allow it to take on medium tanks and some MBT analogues (our engineers have calculated a theoretical maximum performance of ~350mm RHA penetration at the muzzle using high-L/D, jacketed APFSDS). The 105mm gun used in the medium version provides the same ballistics as the famous pre-war L7/M68 guns. This weapon is capable of taking on all comers with present-generation ammunition, and like its predecessor is expected to eventually fire APFSDS ammunition capable of over 400mm of RHA penetration at combat ranges.

 

A compressed air bore evacuation system improves crew comfort and efficiency. The mantlet and recoil system is common to both guns, allowing them to be swapped at a field workshop. The rounds for the main gun are stored in wet racks in the sides (forward of the turret), central hull (behind thew driver's station) and lower turret basket, with only a few ready rounds being carried in the turret basket racks. Rack storage is for 50 rounds regardless of calibre.

 

The coaxial M240 machine gun provides a reliable level of firepower for anti-infantry work. The roof-mounted M2 heavy machine gun provides auxiliary firepower against soft-skinned vehicles, as well as giving the tank a rudimentary anti-aircraft capability.

 

Overall the XM8 offers good firepower, protection and mobility. It also offers a platform with a significant margin for further development.

 

Upgrades

 

M8A1:

dIVMZc2.jpg

The M8A1 upgrade package substantially increases the combat effectiveness of the vehicle by improving first-round hit probability. This is primarily due to the inclusion of the LRS-2 ruby laser rangefinder, TBC-3A ballistic computer and IAPO-3 telescopic sight. All of these components were developed specifically for the XM8 program, and are expected to be in their final configuration within two years of initial rollout.

 

The LRS-2 rangefinder uses a flashlamp-pumped ruby laser, twin photocell optical sensors, quartz timing circuit and the sequential event time sampling approach (with post-sampling amplification) to allow time-of-flight rangefinding using a lower timebase and bandwidth compatible with current electronics. Solid state electronic components allow the system to be fairly compact and robust. Even so the laser and sensor units still require a large, armoured external housing on the mantlet. The housing has a hinged cover on the front which can be opened and closed from inside the vehicle. The rangefinder features both a numerical readout in the gunner’s station and a data link for inputting range data into the ballistic computer. The rangefinder has a maximum operating range of 5km in clear conditions and has an average estimation error of 1%.

 

The TBC-3A replaces the radio in the bustle, which is moved next to the driver at the expense of halving the volume of the right front fuel cell. This electronic ballistic computer also benefits from the use of solid state components. The computer takes input from the gunner (including ammunition selection and manual range input) and rangefinder and uses it to compute a sight offset (horizontal and vertical) for firing. This is then entered into the IAPO-3 sight in order to apply the computed compensation (the existing gunner's telescopic sight is retained as a backup). The computer has a number of operating configurations for various shell types (including all current 85mm and 105mm ammunition), which are stored on a removable magnetic drum. Each drum can store data for up to 32 shell types, with the appropriate type being selected by a dial on the gunner’s station. The computer is also capable of accepting and factoring in wind direction/strength, temperature, humidity and barometric pressure data from an external sensor mast (presently in development under the Integrated Ambient Environment Sensor program).

 

The combination of these devices has been shown to increase first-round hit accuracy against stationary targets at a range of 1000m to almost 90%, and allows first-round hits against stationary targets at a range 2000m to be made over 40% of the time.

 

Additionally, the M8A1 upgrade package includes the addition of sloped spaced armour on the upper hull front, mantlet, turret cheeks and brow. The armour consists of thin RHA plates angled forwards 30’ from the vertical, and is intended to decap and adversely yaw AP projectiles before the main armour is encountered. This is also expected to significantly increase protection against APCR projectiles.

 

The addition of the new components and armour raises the mass of the vehicle to just under 45 tonnes, and substantially increases the unit cost of each vehicle. Nevertheless, the increased combat effectiveness which results from installing these components more than justifies this increased cost.

 

M8A2:

OkSt8HP.jpg

The M8A2 is a speculative upgrade based on known historical trends in tank development, with the presented vehicle being a mock-up. This upgrade package would replace the M8A1 add-on armour with a new composite array designed to defeat improved HEAT warheads and the APFSDS projectiles which are expected to enter the battlefield around 2255. The composite array is a classic NERA design which makes use of thin (2-5mm) steel and aluminium plates sandwiching a thicker (10-20mm) plate made of lower-density material (primarily rubber or plastic, but also glass). The thicknesses, compositions and geometries of the sandwich plates vary depending on their position in the array, but overall densities are estimated at 2.2g/cm3.

 

The total package weighs in at 4.3 tonnes, and provides a substantial increase in armour protection for the crew compartment across the frontal arc of the vehicle. When applied to a ‘blended’ aluminium hull, this results in a vehicle weighing in at just under 37 tonnes. The thick armour arrays are expected to provide around 500mm/740mm KE/HEAT resistance on the upper hull and turret front. This good frontal armour is, however offset by the aluminium hull’s weakness against threats from the side and rear. When applied to an all-steel hull, on the other hand, this results in a vehicle weighing just over 49 tonnes but capable of resisting up to 640mm/800mm KE/HEAT on the upper hull and turret front while still retaining good all-around protection as well.

 

The M8A2 is also expected to benefit from advances in automotive technology, with a projected 850HP turbodiesel engine being used as a weight-for-weight replacement for the existing 750HP unit. This would be allied with an improved transmission system to provide increased cross-country performance and lower driver workload.

 

The single-axis stabilizer is expected to be replaced with an interim two-axis system before the introduction of a fully stabilized system of the pre-war type (ie: combining a gun stabilizer, stabilized sight and barrel registration system). Both systems will be controlled from a fixed handle unit with thumb/finger switches (prototype currently in development), as this is known to provide a slight increase in accuracy by limiting the effects of gross operator movements. The turret traverse and elevation will be handled by a hydro-electric system (currently being researched) with significantly higher power and proportionality of response than the current electrical traverse system. This will, amongst other improvements, result in much faster traverse times.

 

All in all, the M8A2 upgrade package would be expected to allow the M8 design to successfully serve into 2260s and beyond.

wesErmi.jpg

 

135mm L/40 cannon:

hgw2dy3.jpg

  • HEAT-FS (early, fixed-fin): 17.2kg @ 600m/s, ~270mm RHA penetration @ all ranges
  • HE-FS (fixed-fin): @ 27.5kg @ 600m/s
  • AP-FS (fixed-fin): 31kg @ 750 m/s, ~190mm RHA penetration @ 500m
  • HEAT-FS (improved, folding-fin): 29.0kg @ 600m/s, ~310mm RHA penetration @ all ranges
  • APCR-FS (folding-fin): 20kg @ 940m/s, ~230mm RHA penetration @ 500m
  • HEAT-FS (projected, 2nd-gen):  29.0kg @ 780m/s, ~440mm RHA penetration @ all ranges
  • APFSDS (projected, 1st-gen):  7.75kg @ 1330m/s, ~330mm RHA penetration @ 500m
  • Max ME: 8.8MJ
  • Vertical movement: -7'/+20'


The final proposed upgrade to the M8 series of vehicles is the replacement of the 105mm main gun with a 135mm smoothbore gun. The gun as presently developed includes a conventional mid-barrel bore extractor and phenolic resin jacket, and fits into an enlarged version of the existing mantlet gun mount. Ammunition stowage with the 135mm gun is decreased to 35 rounds, stored in new wet racks which slot into the same areas as the existing ones.

 

Although it is currently limited to firing primitive finned projectiles (AP-FS, APCR-FS, HE-FS and HEAT-FS) at a fraction of its capacity, the development of upgraded HEAT-FS and APFSDS is expected to slowly unlock more of the potential of the weapon as time goes on, up to a maximum of around 600mm of RHA equivalence for HEAT-FS and 440mm for APFSDS . Finally, the generous bore of the gun is expected to ease development of GLATGMs as time goes on.

 

Acknowledgements

 

Jeeps (the Sherman site is freaking goldmine)

Various Sketchup users (especially Sketchy@Best, Stefan F., M L. and zdanwoj)

Whoever came up with that Tank Designer spreadsheet that Sturgeon posted

jrb807R.jpg

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XM12E1 Donward - 85mm gun

 

XM12E2 Donward - 100mm gun

 

XM12E3 Donward - 120mm gun

 

XM12E4 Donward - 152mm gun

 

XM13E4 Sandy - 85mm gun and cleft turret


XM13E6 Sandy - 85mm gun and elliptical turret

 

XM15E2 Roach - 100mm gun and no addon armor or stereo RF

 

XM15E4 Roach - 100mm gun and spaced armor array on turret, side skirts

 

XM15E5 Roach - 100mm gun and [classified] armor array on turret and hull, side skirts

 

XM15E7 Roach - 152mm gun and [classified] armor array on turret and hull, side skirts

 

XM15E8 Roach - 152mm gun and new [classified] turret, [classified] armor array on hull, side skirts

 

-for my own reference

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Secondary armament for the Red Fox light tank/scout car is in:6fRYDDP.png
Yes that is a guided missile and yes I will be exhaustively justifying why I believe it to be feasible with the existing tech. The ATGM is MCLOS and easily converted to SACLOS; space will be reserved in the turret for the guidance equipment. The aerodynamic setup is reminiscent of the AT-5 Spandrel, and has been chosen to avoid the most common problem of MCLOS ATGMs as built before the war, and will also be exhaustively discussed in the final submission.
Exact dimensions are still liable to change.

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10 hours ago, N-L-M said:

Secondary armament for the Red Fox light tank/scout car is in:6fRYDDP.png
Yes that is a guided missile and yes I will be exhaustively justifying why I believe it to be feasible with the existing tech. The ATGM is MCLOS and easily converted to SACLOS; space will be reserved in the turret for the guidance equipment. The aerodynamic setup is reminiscent of the AT-5 Spandrel, and has been chosen to avoid the most common problem of MCLOS ATGMs as built before the war, and will also be exhaustively discussed in the final submission.
Exact dimensions are still liable to change.

 

I think Lost said something like X-4 type missiles were feasible, so presumably MCLOS is on the table. The question is just how much it would suck to have to manually guide a missile from your scout car against MBTs. And I mean, SS.11 missiles were plonked on just about everything, so.

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30 minutes ago, Sturgeon said:

SS.11 missiles were plonked on just about everything, so.

SS.11 was indeed an inspiration. And it even has a SACLOS upgrade (Harpon) and a few other details I intend to borrow. But it too suffered from the major flaw in the control layout of first-gen ATGMs, which is why I haven't copied its aerodynamics.

Also friendly reminder that Azon, Fritz-X, Razon, and other WW2 guided bombs were also MCLOS. As previously stated, I will be exhaustively justifying the ability to build this system.

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Just now, N-L-M said:

SS.11 was indeed an inspiration. And it even has a SACLOS upgrade (Harpon) and a few other details I intend to borrow. But it too suffered from the major flaw in the control layout of first-gen ATGMs, which is why I haven't copied its aerodynamics.

Also friendly reminder that Azon, Fritz-X, Razon, and other WW2 guided bombs were also MCLOS. As previously stated, I will be exhaustively justifying the ability to build this system.

 

Like I said, I think MCLOS is OK as per the terms of the OP.

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I must confess that I almost went with a missile-related pet idea of mine* as well. But then I figured that I'd had enough visits from the good idea fairy for one competition.

 

 

 

* A land torpedo, basically. No guidance, it's just designed to fly very fast and in a straight line. Which eases the control requirements to stuff that was available in the 40s, and turns aiming into putting the sight on target and pulling the trigger.

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1 hour ago, N-L-M said:

SS.11 was indeed an inspiration. And it even has a SACLOS upgrade (Harpon) and a few other details I intend to borrow. But it too suffered from the major flaw in the control layout of first-gen ATGMs, which is why I haven't copied its aerodynamics.

Also friendly reminder that Azon, Fritz-X, Razon, and other WW2 guided bombs were also MCLOS. As previously stated, I will be exhaustively justifying the ability to build this system.

I'm looking forward to it.

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16 hours ago, N-L-M said:

Secondary armament for the Red Fox light tank/scout car is in:6fRYDDP.png
Yes that is a guided missile and yes I will be exhaustively justifying why I believe it to be feasible with the existing tech. The ATGM is MCLOS and easily converted to SACLOS; space will be reserved in the turret for the guidance equipment. The aerodynamic setup is reminiscent of the AT-5 Spandrel, and has been chosen to avoid the most common problem of MCLOS ATGMs as built before the war, and will also be exhaustively discussed in the final submission.
Exact dimensions are still liable to change.

 

Those are some really small fins relative to historical MCLOS!

 

 

Also, you need this shirt.

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16 hours ago, N-L-M said:

Secondary armament for the Red Fox light tank/scout car is in:6fRYDDP.png
Yes that is a guided missile and yes I will be exhaustively justifying why I believe it to be feasible with the existing tech. The ATGM is MCLOS and easily converted to SACLOS; space will be reserved in the turret for the guidance equipment. The aerodynamic setup is reminiscent of the AT-5 Spandrel, and has been chosen to avoid the most common problem of MCLOS ATGMs as built before the war, and will also be exhaustively discussed in the final submission.
Exact dimensions are still liable to change.

Looking at the picture again: are those control surfaces on the fins?

 

Because from what I understand about early atgms (which isn't all that much tbh) most of them went with vectoring the thrust instead because of control jitter/proportional response issues. SS-11 and AT-3 did this, for instance.

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1 minute ago, Toxn said:

Looking at the picture again: are those control surfaces on the fins?

 

Because from what I understand about early atgms (which isn't all that much tbh) most of them went with vectoring the thrust instead because of control jitter/proportional response issues. SS-11 and AT-3 did this, for instance.

The tail is fixed, and the canards are monobloc control surfaces. The lines on the fins are just a result of how I defined them.

 

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PID per Ziegler-Nichols from operator command to servo command, servos on open loop.
Where, of course, the full deflection of the operator's joystick would translate to full deflection of control surfaces at launch, decreasing with flight time to allow better accuracy.
Space in the turret has been cleared for the SACLOS conscan device, when such a thing will be ready.
Also, there's a damned good reason I'm not going with TVC.

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      b.      Despite the best efforts of the Agriculture Command, Californian recruits cannot be expected to lift weights in excess of 25 kg at any time.
      c.       Total vehicle weight must remain within MLC 120 all-up for transport.
      F.      Overall dimensions:
      a.      Length- essentially unrestricted.
      b.      Width- 4m transport width.
                                                                    i.     No more than 4 components requiring a crane may be removed to meet this requirement.
                                                                   ii.     Any removed components must be stowable on top of the vehicle.
      c.       Height- The vehicle must not exceed 3.5m in height overall.
      G.     Technology available:
      a.      Armor:
      The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a SEA ORG judge.
      Structural materials:
                                                                    i.     RHA/CHA
      Basic steel armor, 250 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 150mm (RHA) or 300mm (CHA).
      Density- 7.8 g/cm^3.
                                                                   ii.     Aluminum 5083
      More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness.
       Fully weldable. Available in thicknesses up to 100mm.
      Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE.
      Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE.
      Density- 2.7 g/cm^3 (approx. 1/3 of steel).
      For structural integrity, the following guidelines are recommended:
      For light vehicles (less than 40 tons), not less than 25mm RHA/45mm Aluminum base structure
      For heavy vehicles (70 tons and above), not less than 45mm RHA/80mm Aluminum base structure.
      Intermediate values for intermediate vehicles may be chosen as seen fit.
      Non-structural passive materials:
                                                                  iii.     HHA
      Steel, approximately 500 BHN through-hardened. Approximately twice as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 25mm.
      Density- 7.8g/cm^3.
                                                                  iv.     Glass textolite
      Mass efficiency vs RHA of 2.2 vs CE, 1.64 vs KE.
      Thickness efficiency vs RHA of 0.52 vs CE, 0.39 vs KE.
      Density- 1.85 g/cm^3 (approximately ¼ of steel).
      Non-structural.
                                                                   v.     Fused silica
      Mass efficiency vs RHA of 3.5 vs CE, 1 vs KE.
      Thickness efficiency vs RHA of 1 vs CE, 0.28 vs KE.
      Density-2.2g/cm^3 (approximately 1/3.5 of steel).
      Non-structural, requires confinement (being in a metal box) to work.
                                                                  vi.     Fuel
      Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE.
      Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE.
      Density-0.82g/cm^3.
                                                                vii.     Assorted stowage/systems
      Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE.
                                                               viii.     Spaced armor
      Requires a face of at least 25mm LOS vs CE, and at least 50mm LOS vs KE.
      Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 10 cm air gap.
      Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette.
      Reactive armor materials:
                                                                  ix.     ERA-light
      A sandwich of 3mm/3mm/3mm steel-explodium-steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).
                                                                   x.     ERA-heavy
      A sandwich of 15mm steel/3mm explodium/9mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).
                                                                  xi.     NERA-light
      A sandwich of 6mm steel/6mm rubber/ 6mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.
                                                                 xii.     NERA-heavy
      A sandwich of 30mm steel/6m rubber/18mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.
      The details of how to calculate armor effectiveness will be detailed in Appendix 1.
      b.      Firepower
                                                                    i.     2A46 equivalent tech- pressure limits, semi-combustible cases, recoil mechanisms and so on are at an equivalent level to that of the USSR in the year 1960.
                                                                   ii.     Limited APFSDS (L:D 15:1)- Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS.
                                                                  iii.     Limited tungsten (no more than 100g per shot)
                                                                  iv.     Californian shaped charge technology- 5 CD penetration for high-pressure resistant HEAT, 6 CD for low pressure/ precision formed HEAT.
                                                                   v.     The general issue GPMG for the People’s Auditory Forces is the PKM. The standard HMG is the DShK.
      c.       Mobility
                                                                    i.     Engines tech level:
      1.      MB 838 (830 HP)
      2.      AVDS-1790-5A (908 HP)
      3.      Kharkov 5TD (600 HP)
                                                                   ii.     Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled).
                                                                  iii.     Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place).
                                                                  iv.     There is nothing inherently wrong with opposed piston or 2-stroke engines if done right.
      d.      Electronics
                                                                    i.     LRFs- unavailable
                                                                   ii.     Thermals-unavailable
                                                                  iii.     I^2- limited
      3.      Operational Requirements.
      The requirements are detailed in the appended spreadsheet.
      4.      Submission protocols.
      Submission protocols and methods will be established in a follow-on post, nearer to the relevant time.
       
      Appendix 1- armor calculation
      Appendix 2- operational requirements
      Addendum 1 - more armor details
      Good luck, and may Hubbard guide your way to enlightenment!
    • By Sturgeon
      @Toxn
      @Dominus Dolorem
      @Lord_James
      @A. T. Mahan
      @delete013
      @Sten
      @Xoon
      @Curly_
      @N-L-M
      @Sturgeon
       
      detailed below is the expected format of the final submission.
      The date is set as Saturday the 24th of July at 23:59 CST.
      Again, incomplete designs may be submitted as they are and will be judged as seen fit.

      PLEASE REMEMBER ALL ENTRIES MUST BE SUBMITTED IN USC ONLY
       
       
      FINAL SUBMISSION:
      Vehicle Designation and name
       
      [insert 3-projection (front, top, side) and isometric render of vehicle here]
       
      Table of basic statistics:
      Parameter
      Value
      Mass, combat (armor)
       
      Length, combat (transport)
       
      Width, combat (transport)
       
      Height, combat (transport)
       
      Ground Pressure, zero penetration
       
      Estimated Speed
       
      Estimated range
       
      Crew, number (roles)
       
      Main armament, caliber (ammo count ready/stowed)
       
      Secondary armament, caliber (ammo count ready/stowed)
       
       
      Vehicle designer’s notes: explain the thought process behind the design of the vehicle, ideas, and the development process from the designer’s point of view.
      Vehicle feature list:
      Mobility:
      1.     Link to Appendix 1 - RFP spreadsheet, colored to reflect achieved performance.
      2.     Engine- type, displacement, rated power, cooling, neat features.
      3.     Transmission - type, arrangement, neat features.
      4.     Fuel - Type, volume available, stowage location, estimated range, neat features.
      5.     Other neat features in the engine bay.
      6.     Suspension - Type, Travel, ground clearance, neat features.
      Survivability:
      1.     Link to Appendix 1 - RFP spreadsheet, colored to reflect achieved performance.
      2.     Link to Appendix 2 - armor array details.
      3.     Non-specified survivability features and other neat tricks - low profile, gun depression, instant smoke, cunning internal arrangement, and the like.
      Firepower:
      A.    Weapons:
      1.     Link to Appendix 1 - RFP spreadsheet, colored to reflect achieved performance.
      2.     Main Weapon-
      a.      Type
      b.      Caliber
      c.      ammunition types and performance (short)
      d.     Ammo stowage arrangement- numbers ready and total, features.
      e.      FCS - relevant systems, relevant sights for operating the weapon and so on.
      f.      Neat features.
      3.     Secondary weapon - Similar format to primary. Tertiary and further weapons- likewise.
      4.     Link to Appendix 3 - Weapon system magic. This is where you explain how all the special tricks related to the armament that aren’t obviously available using 1960s tech work, and expand to your heart’s content on estimated performance and how these estimates were reached.
      B.    Optics:
      1.     Primary gunsight - type, associated trickery.
      2.     Likewise for any and all other optics systems installed, in no particular order.
      C.    FCS:
      1.     List of component systems, their purpose and the basic system architecture.
      2.     Link to Appendix 3 - weapon system magic, if you have long explanations about the workings of the system.
      Fightability:
      1.     List vehicle features which improve its fightability and useability.
      Additonal Features:
      Feel free to list more features as you see fit, in more categories.
      Free expression zone: Let out a big yeehaw to impress the world with your design swagger! Kindly spoiler this section if it’s very long.
       
       Example for filling in Appendix 1
       Example for filling in Appendix 2
       Example for filling in Appendix 3

      GOOD LUCK!
    • By Sturgeon
      The LORD was with the men of Deseret. They took possession of the hill country, but they were unable to drive the people from the plains, because they had chariots of steel.
      —The Book of Latter Day Saints, Ch 8, vs. 3:10, circa 25th Century CE
       
      BULLETIN: ALL INDUSTRIAL-MECHANICAL CONCERNS
       
      SOLICITATION FOR ALL-TERRAIN BATTLE TANK
       
      The Provisional Government of the Lone Free State of Texas and The Great Plains issues the following solicitation for a new All-Terrain Battle Tank. The vehicle will be the main line ground combat asset of the Lone Free State Rangers, and the Texas Free State Patrol, and will replace the ageing G-12 Scout Truck, and fill the role of the cancelled G-42 Scout Truck. The All-Terrain Battle Tank (ATBT) will be required to counter the new Californian and Cascadian vehicles and weapons which our intelligence indicates are being used in the western coast of the continent. Please see the attached sheet for a full list of solicitation requirements.
       

       
      Submissions will be accepted in USC only.
       
       
      Supplementary Out of Canon Information:
       
       
      I.     Technology available:
      a.      Armor:
      The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a judge.
      Structural materials:
                                                                    i.     RHA/CHA
      Basic steel armor, 360 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 4 inches (RHA) 8 inches (CHA). 
      Density- 0.28 lb/in^3.
                                                                   ii.     Aluminum 5083
      More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness.
       Fully weldable. Available in thicknesses up to 4 inches.
      Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE.
      Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE.
      Density- 0.1 lb/in^3 (approx. 1/3 of steel).
      For structural integrity, the following guidelines are recommended:
      For heavy vehicles (30-40 tons), not less than 1 in RHA/1.75 in Aluminum base structure
      For medium-light vehicles (<25 tons), not less than 0.5 in RHA/1 in Aluminum base structure
      Intermediate values for intermediate vehicles may be chosen as seen fit.
      Non-structural passive materials:
                                                                  iii.     HHA
      Steel, approximately 500 BHN through-hardened. Approximately 1.5x as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 1 inch.
      Density- 0.28 lb/in^3
                                                                  iv.     Fuel
      Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE.
      Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE.
      Density-0.03 lb/in^3.
                                                                v.     Assorted stowage/systems
      Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE.
                                                               vi.     Spaced armor
      Requires a face of at least 1 inch LOS vs CE, and at least 0.75 caliber LOS vs fullbore AP KE.
      Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 4 inchair gap.
      Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette.
      Reactive armor materials:
                                                                  vii.     ERA
      A sandwich of 0.125in/0.125in/0.125in steel-explodium-steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 2 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).
                                                                  viii.     NERA
      A sandwich of 0.25in steel/0.25in rubber/0.25in steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.
      The details of how to calculate armor effectiveness will be detailed in Appendix 1.
      b.      Firepower
                                                                    i.     Bofors 57mm (reference weapon) - 85,000 PSI PMax/70,000 PSI Peak Operating Pressure, high quality steel cases, recoil mechanisms and so on are at an equivalent level to that of the USA in the year 1960.
                                                                   ii.     No APFSDS currently in use, experimental weapons only - Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS.
                                                                  iii.     Tungsten is available for tooling but not formable into long rod penetrators. It is available for penetrators up to 6 calibers L:D.
                                                                  iv.     Texan shaped charge technology - 4 CD penetration for high-pressure resistant HEAT, 5 CD for low pressure/ precision formed HEAT.
                                                                   v.     The subsidy-approved GPMG for the Lone Free State of Texas has the same form factor as the M240, but with switchable feed direction.. The standard HMG has the same form factor as the Kord, but with switchable feed direction.
      c.       Mobility
                                                                    i.     Engines tech level:
      1.      MB 838 (830 HP)
      2.      AVDS-1790-5A (908 HP)
      3.      Kharkov 5TD (600 HP)
      4.    Detroit Diesel 8V92 (400 HP)
      5.    Detroit Diesel 6V53 (200 HP)
                                                                   ii.     Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled).
                                                                  iii.     Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place).
                                                                  iv.     There is nothing inherently wrong with opposed piston or 2-stroke engines if done right.
      d.      Electronics
                                                                    i.     LRFs- unavailable
                                                                   ii.     Thermals-unavailable
                                                                  iii.     I^2- Gen 2 maximum
                                                                  vi.     Texas cannot mass produce microprocessors or integrated circuits
                                                                 vii.    Really early transistors only (e.g., transistor radio)
                                                                viii.    While it is known states exist with more advanced computer technology, the import of such systems are barred by the east coast states who do not approve of their use by militaristic entities.
       
      Armor calculation appendix.
       
      SHEET 1 Armor defeat calculator 4in-54 1200 yd
       
      SHEET 2 Armor defeat calculator 4in-54 2000 yd
       
      SHEET 3 Armor defeat calculator 6in HEAT
       
      Range calculator
       
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