TL9 Heavy Tank

[Nightrider_88]

Heh. So, there was a discussion deep in he Discord, and one of us came up with a set of ideas for a futuristic heavy tank. I liked that idea and since then I'm thinking how well it would translate into GURPS.

So, thing than were said:
Main armament: It's a massive 15cm/60cal high pressure composite barrel gun made from a carbon fiber tube impregnated in a titanium matrix with its bore nitrided about a third its way through, firing a 20kg semi-segmented, sleeved, telescoping, uranium alloy penetrator at 2400m/s using a powerful propellant based on CL-20 and ADN (plus additives, mostly to reduce combustion speed). The resulting rod can go through over 2mRHAe with approximately twice the spalling of a modern one. It uses combustible casings and a super-lightweight sabot made from fancy carbon-carbon composite, which makes the gun very efficient overall and an easy job for the autoloader. The gun can also fire missiles for indirect fire, including kinetic and chemical warheads, as well as other specialist shots as the gun can double as artillery if needed Its not wholly segmented, but the rod is internally shaped in a similar way, with a pattern of ductile and stiff alloy that reduces mushrooming. It's all uranium except for a very thin sleeve of TWIP steel around the penetrator to protect it from shearing. A cool thing is that the projectile does not suffer too hard from overpen as the wide and mushrooming sleeve spalls a lot in the first third or so of the penetration. Should carry 40 rounds, more is not impossible but neither likely, less would be used if needed. It can carry missiles split between two pieces too. All of the ammo spaces are isolated from the crew and each other, covered by panels, armored and fireproofed with a wet gel that may or may not be a horrible ozone depleter
There's two ammo spaces separated by a bulkhead with the loader in the middle, and also a buffer in the turret for rapid fire, tho it should only be filled when the firepower is needed, which us rarely as the tank is designed to one hit kill



Secondary armament: Its main secondary weapon is a heavy armored autocannon on top of the autoloader part of the turret. It has good elevation and depression and a very high fire rate, with enough power to shred IVF and incapacitate tanks; however it has relatively little ammo. It can target independently from the main turret and traverses fast... The idea is that it's able to swap barrels for a smaller one if the low ammo proves a weakness (e.g. urban combat), but so far I've had trouble designing such a loading mechanism... It also has canisters for loitering munitions A laser for drone defense that could be used as a weapon too An automatically aimed 20mm cannon which, depending on the version of the tank is mounted in various places, on top of the cannon, coaxial to it, to the gun or on the back of the tank, and it's a bit of another layer of point defense plus ****ing infantry. The 50cal is pretty boring but the 2cm has two rounds: a high velocity incendiary sabot and a big fat timed fuze shrapnel, with AHEAD-like design, but the casing is a continuous rod and the beads are long and made of a flammable uranium alloy.

Front hull armor: ERA followed by a complex composite armor mostly based on tiled NXRA, using PE/PE as rubber with a bit of explosive mixed in. The plates contain fancy **** like nanocrystalline titanium with various treatments, TWIP steel or superplastic CMC

Side armor: two layer ERA, one shaped charge the other flier plate based, angled in a sight V, triggered early by magnetic detectors, followed by a tightly packed composite of fancy ceramics and stupidly ductile steels, in thick plates separated by rubber and glassed titanium foam spacers. The side armor is less weight efficient but incredibly space efficient, and it saves weight from ERA.

Powerplant: Also there's a variant using aluminum fuel, which is more expensive, slightly heavier and harder to refuel but doubles range and adds a bit of protection to the engine. It also could run underwater (wirming out the how) and has no exhaust.
Its fed as a dust, dissolved in gallium and fed through a fuel cell, with the oxide dropped to the ground as incredibly fine crystals precipitating out of the solvent
Another cool thing of alu is that it needs very little air (5ish times more vs 15ish for diesel) so that's a much smaller weakness at the intake
In theory it could run underwater too, this is very useful for crossing large water bodies without a snorkel, but it's need to be figure out how to make the engine be able to switch modes without pulling it out

60 tons. Unmanned turret. RHA equivalent of the hull armor should be about meter.

[Varyon]

A lot of this is going to be below GURPS resolutions. For the armor, you could probably look at the materials from the "Cutting Edge Armor Design" article (while focused on personal armor, vehicular armor can be designed with that article as well). For RHA equivalence, 1 meter RHA is around DR 2750 in GURPS - so the tank's hull would have around DR 2750 while the main gun would have penetration that averaged out to around 5,500 - roughly 785d(2) pi+ inc (although if following UT rather than HT, this could instead be more like 6dx50(5) pi inc).

[Fred Brackin]

Originally Posted by Varyon

the main gun would have penetration that averaged out to around 5,500 - roughly 785d(2) pi+ inc (although if following UT rather than HT, this could instead be more like 6dx50(5) pi inc).

No, you're not going to get (5) with DU. Traditionally that's a (3). I get 6x 525(3). Pretty much all the technobabble is beyond Gurps level of resolution as noted and some of it is dubious. The given size and velocity do not scale up properly from the Abrahms' 120 mm gun.

There wasn't enough data on the secondary gun (or even if it's all one gun) and I'm not sure what it's for

Apologies, I left out a step in my math. The 150mm main gun (I try not to report bore sizes in centimeters) should do 6Dx87.5(3) and the scaling up from the Abrahms 120mm is alright. Now you can save all the technobabble about the penetrators' construction for why it doesn't totally fall apart at 2400meter per second. I doubt that anything about "mushrooming" would be useful.

[Varyon]

Originally Posted by Fred Brackin

No, you're not going to get (5) with DU. Traditionally that's a (3). I get 6x 525(3). Pretty much all the technobabble is beyond Gurps level of resolution as noted and some of it is dubious. The given size and velocity do not scale up properly from the Abrahms' 120 mm gun.

There wasn't enough data on the secondary gun (or even if it's all one gun) and I'm not sure what it's for.

APEP in UT is described as basically being FSDSDU (but using something other than DU) and has AD (5), while I believe HT simply gives all the DU munitions AD (2) and mounting damage (so handling things the HT way would have meant APEP would have been x2.5 damage and AD (2) rather than AD (5)), but I'm away from my books at the moment and can't check. I honestly don't know what all the terms in the buzzword-soup describing the round wind up actually meaning for it, but figured maybe they'd approximate something like FSDSDU... although then maybe a 15mm barrel would actually only wind up with pi rather than pi+ (I think FSDS can downgrade piercing class two steps in some cases, but I could be misremembering).

[Fred Brackin]

Originally Posted by Varyon

APEP in UT is described as basically being FSDSDU (but using something other than DU) and has AD (5), ).

No, it doesn't. I'm not away from my books. APEP is (3).

What i'm actually relying on though is from VE2. Armor Piercing Fin Stabilized Discarding Sabot Depleted Uranium or APFSDSDU in Ve2 has (3) as well and the cannon of the MBT in that book (which David Pulver designed to fit the M1A3 Abrahms) does 6x30(3).

The general rule I seem to remember is that weapons of 25mm or higher don't lose a P-class from going armor-piercing. A 150mm certainly wouldn't.

[Varyon]

Originally Posted by Fred Brackin

No, it doesn't. I'm not away from my books. APEP is (3).

Ah, I was probably thinking of HyperDense or something then, thanks.

Originally Posted by Fred Brackin

The general rule I seem to remember is that weapons of 25mm or higher don't lose a P-class from going armor-piercing. A 150mm certainly wouldn't.

... Oh, the tank's main gun is 15 cm, I was reading it at 15 mm. In my defense, I was also thrown off by the "60 cal," which seems like it would refer to .60" caliber (like how .50 is often called "50 cal") rather than ~6.0" caliber. I thought maybe it was meant to be a shockingly-small caliber (something more for dealing with light vehicles than tanks) that still managed to pack a huge punch. pi++ it is!

[mlangsdorf]

Design wise, I'm not sure why the tank has a honking huge main cannon firing at crazy high speeds to get really good armor pnetration and then has relatively weak armor protection. The gun can penetrate 2m of RHAe but the tank has 1m of RHAe equivalent armor. What is this thing supposed to be fighting? It massively overkills itself in mirror matches and fights best against a foe with thick armor and a relatively puny gun.

I'd be inclined to go with a 125mm to 130mm cannon, using ETC/ETK type propellant to fire long rod penetrators very fast. The smaller caliber means everything weighs less, so more of the available weight can be devoted to thicker armor, better point defense systems, or more ammo. 40 rounds seems low to me, but I guess modern M1A2 Abrams only carry that much.

[johndallman]

Originally Posted by Nightrider_88

The 50cal is pretty boring . . .

You also want at least one 30cal machine gun in the turret. Using anything heavier on unarmoured people and soft-skinned vehicles is pointless, and you can carry lots of ammunition. It isn't a cool weapon, but it will get used a lot.

[Polydamas]

Originally Posted by Nightrider_88

Heh. So, there was a discussion deep in he Discord, and one of us came up with a set of ideas for a futuristic heavy tank. I liked that idea and since then I'm thinking how well it would translate into GURPS.

60 tons. Unmanned turret. RHA equivalent of the hull armor should be about meter.

How many human crew: three?

One disadvantage of increasing the bore size is that its likely to slow reaction to (eg. "crunchy with an antitank missile just popped up at 1500 metres and 10 o'clock")

[weby]

Originally Posted by Nightrider_88

Main armament: It's a massive 15cm/60cal high pressure composite barrel gun made from a carbon fiber tube impregnated in a titanium matrix with its bore nitrided about a third its way through,

Does not sound like a likely armament. The early TL 9 will likely still use 120mm guns, then maybe, a bit larger like a 130mm or 140mm and then more likely some other technology.

The problems with a larger gun are many:
-Larger gun ammo is heavier and more bulky, if the proportions stay the same in the ammo, the 150mm ammo would be twice the mass and more importantly volume, so you could carry less ammo.
-Larger gun is longer to get the same length rating and a 120mm/L50 gun is already annoyingly long.
-autoloader: see below

Then the actual proposed technology:
Having carbon tubes as a contact surface to a projectile sounds unlikely as such construction is really not very abrasion resistant and thus would not last many shots.

firing a 20kg semi-segmented, sleeved, telescoping, uranium alloy penetrator at 2400m/s using a powerful propellant based on CL-20 and ADN (plus additives, mostly to reduce combustion speed).

A 20kg uranium penetrator that is more than four times the typical DU projectile today and about three times to heaviest DU penetrators. In the most extreme cases you are talking about 32 to 1 diameter to length ratio for penetrators instead of the more traditional say 27:1.

As you want as long as possible penetrator that does not shatter and with better alloys I guess thus that your gun would likely thus fire a say 40:1 penetrator to give it best possible penetration. Thus the penetrator would be about 1.3 meters long.


You want a 2400m/s muzzle velocity. Estimating that the sabot would need to be close to current 50% of projectile mass due to the huge bore you want to fire the 32mm diameter dart. Thus you are around 86 mj muzzle energy. That is about 6-7 times 120mm apfsdsdu ammo. Basically your gun would need to contain that in about double the volume of 120mm gun. That is some interesting pressures and would require quite sturdy design.

Making it telescoping would require a much sturdier sabot as the uranium rod is very fragile to sideways effects given how thin it is. So that sounds like an "interesting" development path to get it all working.. I would expect a lot of snapped penetrators in the process.

The resulting rod can go through over 2mRHAe with approximately twice the spalling of a modern one. It uses combustible casings and a super-lightweight sabot made from fancy carbon-carbon composite, which makes the gun very efficient overall and an easy job for the autoloader.

Just no. The penetrator is only 1.3 meters long and thus it will not penetrate that far until it is ablated away.

Your super lightweight sabot cannot survive the explosion that is the thing needed to reach that muzzle velocity, specially if you go for the telescoping case.

As for autoleader handling easily the at least 1.5 meter long and 15cm diameter object. Well, way less handily than the 12cm diameter 1 meter long 120mm ammo of today.

The gun can also fire missiles for indirect fire, including kinetic and chemical warheads, as well as other specialist shots as the gun can double as artillery if needed Its not wholly segmented, but the rod is internally shaped in a similar way, with a pattern of ductile and stiff alloy that reduces mushrooming.

You do not want your tanks to act as artillery if it can be avoided. A high pressure tank gun has low maximum number of short that can be fired.

Yes, tanks do and should act in direct fire role to support other forces, but using them for indirect fire is wasting the lifespan of the gun in tasks better done by other platforms.

It's all uranium except for a very thin sleeve of TWIP steel around the penetrator to protect it from shearing. A cool thing is that the projectile does not suffer too hard from overpen as the wide and mushrooming sleeve spalls a lot in the first third or so of the penetration.

Uuh? TWIP? no idea what you are talking about so cannot comment, but sounds..

Should carry 40 rounds, more is not impossible but neither likely, less would be used if needed. It can carry missiles split between two pieces too. All of the ammo spaces are isolated from the crew and each other, covered by panels, armored and fireproofed with a wet gel that may or may not be a horrible ozone depleter
There's two ammo spaces separated by a bulkhead with the loader in the middle, and also a buffer in the turret for rapid fire, tho it should only be filled when the firepower is needed, which us rarely as the tank is designed to one hit kill

Why a buffer? An unmanned turret is the likely solution and building an autoloader for such that pulls from the hull under the turret does not sound very difficult. Obviously such ammo bins would need to have the blow out panels and so on.

Secondary armament: Its main secondary weapon is a heavy armored autocannon on top of the autoloader part of the turret. It has good elevation and depression and a very high fire rate, with enough power to shred IVF and incapacitate tanks; however it has relatively little ammo. It can target independently from the main turret and traverses fast...

An autocannon does make some sense, but historically it has been seen better to put the autocannon in a separate vehicle(the IFV) as giving more roles to an MBT is normally not a good idea as they are heavy enough already and busy enough for the crew.

If used you would likely want a fairly high load of ammo to deal with drones, autonomous ground combat units and such.

Also regardless you want a machinegun, as you will also likely meet infantry unless the enemy is totally incompetent. If all infantry is in bodyarmor it would likely be something larger like a 12.7mm, but else a normal 7.62 or similar would do the job.

The idea is that it's able to swap barrels for a smaller one if the low ammo proves a weakness (e.g. urban combat), but so far I've had trouble designing such a loading mechanism...

Not likely.. weapons of war should be as simple as possible, thus you add the MG as separate weapon not a fancy and easy to break change thing.

It also has canisters for loitering munitions

Programmable ammunition is much more likely. That is the ammunition explodes at the distance set when fired. That could be used against drones, against troops behind cover and so on. But really drones should be engaged by other units not the MBT.

A laser for drone defense that could be used as a weapon too

A very possible development.

An automatically aimed 20mm cannon which, depending on the version of the tank is mounted in various places, on top of the cannon, coaxial to it, to the gun or on the back of the tank, and it's a bit of another layer of point defense plus ****ing infantry. The 50cal is pretty boring but the 2cm has two rounds: a high velocity incendiary sabot and a big fat timed fuze shrapnel, with AHEAD-like design, but the casing is a continuous rod and the beads are long and made of a flammable uranium alloy.

A 20mm is a bit small autocannon for explosive payload, in most casees you would much prefer the 30mm/40mm rounds from the accompanying IFV. So in case of a 20mm, no autocannon would likely be better for the tank.

Front hull armor: ERA followed by a complex composite armor mostly based on tiled NXRA, using PE/PE as rubber with a bit of explosive mixed in. The plates contain fancy **** like nanocrystalline titanium with various treatments, TWIP steel or superplastic CMC

Likely more vehicles would also use some development of the later Leopard 2 tank turrets with space to snap long rod penetrators that do not hit square on.

Side armor: two layer ERA, one shaped charge the other flier plate based, angled in a sight V, triggered early by magnetic detectors, followed by a tightly packed composite of fancy ceramics and stupidly ductile steels, in thick plates separated by rubber and glassed titanium foam spacers. The side armor is less weight efficient but incredibly space efficient, and it saves weight from ERA.

Hard kill active protection systems would be a likely in use instead of the proximity fuse ERA.

Powerplant: Also there's a variant using aluminum fuel, <snip>It also could run underwater (wirming out the how) and has no exhaust.<snip>

Aluminium is indeed a possible fuel, but the underwater use is questionable at best. Historically the idea has come up every now and then but the number of times it has been used is minuscule. Besides the battery part likely hydrid power train should be enough for any such.

The interesting question on the powertrain would be the balance of the powerplant and the batteries.

60 tons.

Not realistic. Already today we have some tanks over 70 tons and you want to add a bigger gun and an extra weapon system.

Unmanned turret.

Very likely.

RHA equivalent of the hull armor should be about meter.

Against what? Modern armors are not uniform against different attack types.

Nothing in your design indicates how it would get that against kinetic penetrarors.