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Old 03-14-2023, 07:47 AM   #1
Nightrider_88
 
Join Date: Nov 2019
Default TL9 Heavy Tank

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.
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Old 03-14-2023, 08:34 AM   #2
Varyon
 
Join Date: Jun 2013
Default Re: TL9 Heavy Tank

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).
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Old 03-14-2023, 09:48 AM   #3
Fred Brackin
 
Join Date: Aug 2007
Default Re: TL9 Heavy Tank

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Originally Posted by Varyon View Post
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.
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Old 03-14-2023, 10:31 AM   #4
Varyon
 
Join Date: Jun 2013
Default Re: TL9 Heavy Tank

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Originally Posted by Fred Brackin View Post
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).
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Old 03-14-2023, 10:46 AM   #5
Fred Brackin
 
Join Date: Aug 2007
Default Re: TL9 Heavy Tank

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Originally Posted by Varyon View Post
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.
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Old 03-14-2023, 11:03 AM   #6
Varyon
 
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Default Re: TL9 Heavy Tank

Quote:
Originally Posted by Fred Brackin View Post
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.

Quote:
Originally Posted by Fred Brackin View Post
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!
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Old 03-14-2023, 11:20 AM   #7
mlangsdorf
 
Join Date: Aug 2004
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Default Re: TL9 Heavy Tank

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.
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Old 03-14-2023, 11:21 AM   #8
johndallman
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Default Re: TL9 Heavy Tank

Quote:
Originally Posted by Nightrider_88 View Post
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.
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Old 03-14-2023, 11:28 AM   #9
mlangsdorf
 
Join Date: Aug 2004
Location: Austin, TX
Default Re: TL9 Heavy Tank

Quote:
Originally Posted by Varyon View Post
... 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!
60 calibers, in this case, is the barrel length. So a 150mm bore and a 9 m barrel. Which is really annoyingly big. An M1 Abrams with an L/44 main gun is 9.9m long including the 5.3m of gun barrel, so this tank would be around 13m long.

I know the tank designers are pushing for bigger calibers, but much like the Navy artillery designers before them, I think they're hitting the point of diminishing utility.
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Old 03-14-2023, 11:34 AM   #10
Rupert
 
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Default Re: TL9 Heavy Tank

Note that HT gives DU ammo as (2) these days.

Also, this is a claim of double the penetration of a modern Russian/Chinese 125mm APFSDSDU round for only slightly more than double the muzzle energy. OTOH, the 125mm claims are for 1000m, so I suppose that's possible (but that means the muzzle penetration of modern 120mm and 125mm guns isn't far behind the performance claimed for this monster). I'm not convinced it's worth the investment.

The autoloader, missiles, etc. are all in the reach of modern weapons, it's just a matter of putting together the features of the various modern tanks in a single vehicle.

Also - I'm not sure why it's worth using such a weapon system as artillery except as an improvisation - artillery systems fire many rounds, and thus barrel life is a major consideration. One thing this gun will not have is a great barrel life, which is acceptable in a tank gun, but not in an artillery piece.

Note that in the current war the Ukrainians are finding that many modern western artillery systems are poorly suited for the type of war they're fighting because they don't have a very high sustained rate of fire due to barrel heating. It appears that wars' appetite for shells is as great as ever.
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