Competition: Californium 2250

[Kal]

medium tank, 48 x 120mm rounds, (46 with 2 starter placeholders)  HEAT, Autocannon

rounds are now 20kg class

rate of fire, sustained 30 rounds per minute. (40 rounds per minute rapid)

[Toxn]

A 'just for fun' version:

 

The Stumpy Twinblade modification uses two low-pressure 85mm/L61 guns fed by 8-shot autoloaders to drown an opponent in rapid-fire HEAT-FS warheads.

The drums are each fed by two 4-round secondary loading systems in the turret rear (when the gun is levelled), which in turn can be topped up by the commander from two 16-round ammunition racks located in the fighting compartment. Each gun has a fire rate of 60 rpm and can be raised/lowered +30/-5 degrees. The drums alternate between high-penetration HEAT-FS, HEDP-FS and HE shells, with each gun having a different shell. The shells are ballistically matched (each weighing 9.7kg and moving at 650m/s), and the guns sighted to converge at around 1.5km. The high-penetration HEAT-FS shell would achieve around 360mm RHA penetration, with the HEDP-FS shell achieving 210mm RHA penetration with much greater behind-armour effect. 

 

The guns retain a fume extractor to prevent fouling building up behind the breech. In addition, their thermal sleeve includes a water circuit for cooling purposes. The water tanks double as the fighting compartment ammunition racks - minimising the chances of a catastrophic ammunition explosion in the fighting compartment. The turret composite armour package consists of a block of turret  frontal armour ahead of the commander and gunner's stations, with the sides being protected by the guns and their armoured housings. The hull configuration and armour remains the same as the base-model Stumpy.

 

The Twinblade would be intended to act as an ambush predator - launching a salvo of shells at targets of interest before backing off into cover to reload. Targets could be bracketed if the range was uncertain, with known ranges allowing smaller salvos to be fired per target. Although 360mm RHA is just barely capable of getting through a standard Norman turret front, the lower velocity of the shells would mean that arcing shots striking the top armour would be pretty common. In addition, a rain of 16 shells launched in quick succession would be almost certain to result in at least a mission kill so long as a few strike home. The Twinblade's high gun elevation also allows it to do service as a self-propelled artillery piece, with proximity-fuzed HE shells providing credible anti-aircraft capability against slow or low-flying threats. Finally; in urban environments the high elevation angle allows the Twinblade to sweep multistory buildings with fire.

 

 

[N-L-M]

But what about the big bouy and lil bouy? The people want to know!

[Toxn]

Lil bouy got finished to the point where I was essentially happy with her (bar her insane armour fraction) and was just fixing up some hull elements.

 

Brick got abandoned at the 90% mark. Big bouy was a joke tank I whipped together in an evening and which doesn't actually work .

 

I'll put up a finalised version of Lil bouy (with the steel hull and ERA) and an SPG variant I was working on before I switched to Stumpy.

 

Edit: I'll happily admit that Lil Bouy was one of the prettier tanks I've ever designed.

[Kal]

Gillette NERA

 

+ NERA Inserts and ERA around turret, with bonus heavy NERA

 

co axial 30mm autocannon, equivalent to M230LF, rounds ballistically matched to 120mm rounds.

 

engine is 6TDF,  early 5TDF were 700 hp (522 kW ), so equivalent generation 6TDF would've been about 20% more, so 840hp or 626kW. 

 

opposed piston 2 stroke diesels can be assembled to allow power take on both ends (due to twin crankshafts), the transmission will be twin transmissions, each with lockable fluid torque convertor,  and a ravigneaux planetery gearset giving 2 forward gears and 1 revers gear.  there are no differentials.    general principle of veering left or right is that the side to turn to, is unlocked (and can be slightly braked if desired), the side to turn from, is locked.   Tank can rotate on its centre as tracks are independent.   These are all compact, pancake technologies that were available back in the 50s and 60s.   The outline of the motor and transmission is behind the man, it is compact, 6TDF motors are magic, if exhaust emissions are not a high concern.

 

[N-L-M]

7 hours ago, Kal said:

equivalent to M230LF, rounds ballistically matched to 120mm rounds.

You either have a very low energy and sad 120, or a more powerful 30mm. 30x113mmB is not up to the task of matching even high pressure 120mm HE rounds, thanks to being low velocity and having poor sectional density.

7 hours ago, Kal said:

general principle of veering left or right is that the side to turn to, is unlocked (and can be slightly braked if desired), the side to turn from, is locked.

Clutch-and-brake steering on a tank that size is... somewhat brave.

[Toxn]

1 hour ago, N-L-M said:

You either have a very low energy and sad 120, or a more powerful 30mm. 30x113mmB is not up to the task of matching even high pressure 120mm HE rounds, thanks to being low velocity and having poor sectional density.

Clutch-and-brake steering on a tank that size is... somewhat brave.

My understanding is that it's even braver than that...

[Kal]

5 hours ago, N-L-M said:

...

Clutch-and-brake steering on a tank that size is... somewhat brave.

 

Object 432, sure looks like they simply bolted on the transmission onto each end of the opposed cylinder 2 stroke  diesel. So this begat the T64 which seems to follow the same philosophy

[Kal]

T 90, engine is more conventional, but it also looks like a nil differential design, instead they split the transmission, then place the gearing afterwards.  So instead of gears then differential,

 

it is primary split/reduce then, two planetary final gearboxes and two planetary final drives.

 

[Kal]

Oplot http://morozov.com.ua/en/bronetankovaya-tehnika-i-vooruzhenie/tanki/razrabotki/oplot/

again, no differential, twin gear sets.  They seem to use 7 spd auto transmission, instead of emphasizing twin big pancake torque convertors

[Kal]

automotive torque convertors.

[Toxn]

So, while working on the finalised version of Lil Bouy during my lunch break, I had cause to revisit a Kontakt-1 analogue again.

 

And, holy shit: when you put the bricks at 60' from the vertical, it provides amazing protection. We're talking an extra 345/75mm CE/KE on the flat, and 485/160mm at a 45' angle. Definitely worth sticking all over any putative MBT design, given that you're talking about ~6kg per brick.

 

 

[Kal]

6 hours ago, N-L-M said:

You either have a very low energy and sad 120, or a more powerful 30mm. 30x113mmB is not up to the task of matching even high pressure 120mm HE rounds, thanks to being low velocity and having poor sectional density.

 

with a longer barrel, the m789 seems to exit at 850m/s the M230LF, sad, but acceptable if there is follow on rounds.

Obus G was reportedly 1000m/s, and accurate to 3000m, since M789 is better documented (in english) I'll scale back to 850m/s

 

Obus G projectile weighs 10.85kg (for 105mm round), scaled down to 30mm that would be 253grams,  M789 projectile is 229grams 9% difference, proposed  120mm series projectile are 14.656kg to match M789 (229grams x4x4x4)

m789 is a 30mm round with a proportionally large fuze,  120mm rounds's fuze is proportional much less significant.

 

[Toxn]

The final version of Lil Bouy:

[Toxn]

The Lil Bouy SPG variant "Zvero-bouy":

[Toxn]

I'll noodle around with descriptions later.

 

For now:

• The Lil Bouy is as previously described, with a slightly higher-powered 130mm L/55 gun, Kontakt-1 style ERA package and a stereoscopic rangefinder for the gunner. The ERA package is necessary to allow it to survive 60/160mm ATGM shots to the front and lower hull sides. The all-up weight is something like 75mt.
• The SPG variant has thicker frontal and upper side armour, and sports a 200mm L/35 gun. The gun has the same muzzle energy as the 130mm gun, and uses a variant of its propellant charge. The gun is fed by conveyor and hoist-style autoloader which sits on the rear of the fighting compartment. The autoloader, in turn, is fed by an ammunition rack which takes up most of the hull area underneath the crew's feet. The ammunition rack feeding the autoloader can store up to 20 rounds, with nearly all of it being HE.
• The SPG's gun runs at 210MPa, so a hilariously overpowered tandem heat shell (400/1080mm RHA penetration) is available in case you need to kill a bolo or something. A more sensible HEAT-FS shell using a HEDP charge (700mm RHA penetration) is available if you want to put fist-sized holes into fortresses and then roast/impale everyone inside.

[Kal]

Hull casting is 13.5 tonne, 100mm thick Magnesium, 2 internal 100mm Mg bulkheads, enclosed hull volume is 34m3, 

3 tank variants  from same casting.

amphibious light tank (rear engine) 33 tonne (ERA only)

Main battle tank (rear engine) 45.6 tonne (ERA and NERA combo)

Heavy Tank (dual engine, rear and front) 65.6 tonne (lots NERA)

[Kal]

thanks for Toxn's simplification,  MBT 456 (45.6 tonne)

 

Turret front:

• KE: 120mm gun (500mm) (statistical OK)
• CE: ATGM (360/960mm) (FAIL main charge)
• CE: ATGM (300/600mm) (FAIL, hmmm, not satisfactory)

Turret sides:

• KE: 105mm gun (247mm) (curent fail, but pass if 25mm Texto replaced by 25mm HHA)
• CE: ATGM (255/679mm) (tandem charge fail)

Turret rear:

• KE: 155mm HE (45mm) (OK)
• CE: DPICM (160mm) (FAIL)

Turret, roof:

• KE: 155mm HE (45mm) (OK)

 

Hull belt front:

• KE: 120mm gun (500mm) (OK)
• CE: ATGM (360/960mm) (OK)

Hull front upper glacis:

• KE: 120mm gun (500mm) (significantly OK)
• CE: ATGM (360/960mm) (significantly OK)

Hull rear:

• KE: 155mm HE, (45mm ) (OK)

Hull floor:

• KE: 3x10kg mines (~50mm) (OK)

 

Ammunition

48 x 120mm, loaded. (1 tonne)

2,400 x 30mm HEDP, loaded. (1 tonne, inclusive links)

 

also

cost effective, novel, hybrid 120mm ammunition, to deal with the Norman menace.