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Old 12-06-2022, 07:17 PM
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Tegyrius Tegyrius is offline
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Default Does 4e change the viability calculus for the LAV-75?

Having recently discussed the MBT issue in 4e, I thought it might be interesting to tinker with everyone's favorite apocryphal light tank, the LAV-75. Back in 2009, we had a rather long and productive thread on it, which yielded a few different variants and development histories. I'm too lazy to use that entire thread, but I did cherry-pick the bits dealing with the hypothetical upgrade to a 90mm low-pressure gun system (presumably the same one for which we already have 2e canon stats courtesy of the MPGS-90).

So what does the LAV-75 look like in 4e? Using the conversion rules in the back of the Referee's Manual, we get a stat line that looks a little something like this (apologies to those on mobile):



(I deviated from canon by providing both pintle and coaxial MGs. Rebellion is a heady drug.)

So, not really awful. It suffers in the tactical mobility department, most notably being slower off-road than the tanks it was intended to slow down in its original RDF conceptualization. However, it's actually faster on a road march than any of the T-series. But life and AFV design are about compromises.

The big objections to the LAV-75 have always centered around the gun, though. Does it fare any better in 4e rules than it did in previous editions (much less real-world acceptance testing)? Well, let's take a look at how the 75mm Ares cannon, as well as the 90mm low-pressure gun of the forum's LAV-75A1, convert to 4e:



(I stuck the 75mm with Reliability 4 because I am cruel. Forgiving referees may feel free to ignore that.)

Okay, so the design objective of both of these guns was to kill Soviet tanks of the types likely to be encountered in Southwest Asia - so anything up to and including a T-72. How do they stack up?

As it turns out, slightly better than in real life. Looking at frontal armor, the T-55 comes in with 6 (actually worse than the LAV-75, by Free League's own conversion rules), the T-62 has 7, the T-64 goes to 8, and the T-72 goes to 9, while the T-80 (unlikely in the originally-intended AO) goes to 10. For cracking armor, both guns get roughly equal performance (save for range) out of their HEAT and APFSDS rounds. For the 75mm, we're looking at Damage 6, Armor -1; for the 90mm, it's Damage 7, Armor -1.

With that Armor -1 modifier, the 75mm will consistently penetrate the frontal armor on a T-55. It won't automatically crack a T-62 or T-64, but a good hit or luck with ammo dice, because it's burst-capable may boost the damage enough to go internal. The Penetration Limit rule on p. 82 of the Player's Manual keeps it from being able to get frontal penetration on a T-72 or T-80. To the sides and rear, of course, good hits are much more feasible, though they still rely on extra successes or ammo dice to pop a T-64 or higher.

How about the 90mm? Much the same story, but up one level: reliable frontal penetration on a T-55 or T-62, but dependent on superior marksmanship to find a weak spot in the face of a T-64 or T-72. However, marksmanship is actually more critical here because the low ROF of a conventional cannon restricts the use of ammo dice.

Let me know what I've missed in the numbers.

- C.
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Clayton A. Oliver • Occasional RPG Freelancer Since 1996

Author of The Pacific Northwest, coauthor of Tara Romaneasca, and creator of several other free Twilight: 2000 and Twilight: 2013 resources.

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Old 12-07-2022, 06:34 PM
ToughOmbres ToughOmbres is offline
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Default 4E LAV 75

Don't own the 4th edition T2K but wonder if the original LAV 75 autoloader would warrant special attention for potential breakdown/extra maintenance?

The way I understood it the LAV-75 autoloader was supposed to be similar to the AMX 13 with a kind of half moon or circular "clip" or is that completely incorrect?
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Old 12-07-2022, 07:34 PM
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According to this page, it went through a couple of different iterations. The one you're describing seems to be the first generation, if I'm interpreting this correctly:

Quote:
On the HIMAG, the six-round carousel that fed the breech was part of the gun cradle, meaning that the carousel would move with the gun as it elevated or depressed. On the HSTV-L, the six-round carousel was mounted directly below the gun breach in a static position. The breech would always remain in the same position relative to the turret, since it was mounted along the trunnion line. This allowed for both the carousel and gun to be replenished continuously despite the gun’s position.
(Also, I need to fix my stat lines to include a larger magazine and to add thermal imaging.)

- C.
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Old 12-07-2022, 09:00 PM
castlebravo92 castlebravo92 is online now
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I own 4e, but haven't read in depth on the ruleset.

I would point out though that there's video of Ukraine taking out a T-72B or T-80 with repeated 30mm frontal arc hits from an APC, so I'm thinking a 75mm or 90mm APFSDS or HEAT round might do the job as well. Both of the HEAT rounds should easily be able to slice through the T-62, which only had around 200mm of non-composite RHA on the turret.
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Old 12-08-2022, 06:19 AM
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The key limiting factor in the 4e rule set is:

Quote:
Originally Posted by 4e Player's Manual, p. 82
PENETRATION LIMIT: If the base damage rating of the weapon is 2 steps lower than the modified armor level or more, the attack is fully deflected, no matter how many [reticle] or [bullet] were rolled for the attack.
(Emphasis is Free League's. The same rule also appears on p. 73 in the context of infantry combat.)

This has the reasonable effect of minimizing "golden BB" hits, as well as overcoming some of the improbable penetration results that, for instance, Twilight: 2013's rules yielded before errata. However, it also negates the potential for multiple rapid-succession hits in the same spot to "peck" through armor.

Thus, in this game engine, a 30mm AC firing AP ammo (Damage 6, no armor penetration modifier) will never get a frontal kill on a T-72 (Front Armor 9), even if an expert gunner firing at max rate generates 7 total successes. While this may not align well with current real-world evidence, we need to bear in mind that any game engine is a simplified mathematical model of reality. Individual correspondents will differ on the degree of simplification they're able or willing to accept before their suspension of disbelief is rudely violated...

- C.
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Clayton A. Oliver • Occasional RPG Freelancer Since 1996

Author of The Pacific Northwest, coauthor of Tara Romaneasca, and creator of several other free Twilight: 2000 and Twilight: 2013 resources.

If you dislike change, you're going to dislike irrelevance even more.
- General Eric Shinseki
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Old 12-08-2022, 09:26 AM
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Raellus Raellus is offline
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Quote:
Originally Posted by castlebravo92 View Post
I would point out though that there's video of Ukraine taking out a T-72B or T-80 with repeated 30mm frontal arc hits from an APC, so I'm thinking a 75mm or 90mm APFSDS or HEAT round might do the job as well. Both of the HEAT rounds should easily be able to slice through the T-62, which only had around 200mm of non-composite RHA on the turret.
Was it a hard or soft kill? Did the 30mm hits actually penetrate the frontal turret armor and kill/incapacitate the crew and/or detonate the main gun armor? Or, did they destroy the turret optics and whatnot, rendering the vehicle toothless? Or, did the 30mm hits impel the crew to panic and abandon ship, as it were?

I haven't applied all of the 4e vehicle combat rules yet, so I'm not sure if they model any of those soft kill options in the scenario described. I'll have to take a closer look.

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Last edited by Raellus; 12-08-2022 at 11:43 AM.
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Old 12-08-2022, 04:18 PM
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Rae, you'll want the non-penetrating column of the Component Damage table on page 84 of the Player's Manual. Possible damage from hits that don't punch through the armor includes track/wheel, weapon systems, fire control systems, antennas, external stores, and exposed passengers. There's also a chance of a ricochet, which doesn't hit anything important but forces an immediate CUF check for every exposed passenger/crew member or adjacent dismounted character.

So... mission kills from non-penetrating hits are possible through a combination of immobilization, weapon destruction, and disabled comms.

- C.
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Clayton A. Oliver • Occasional RPG Freelancer Since 1996

Author of The Pacific Northwest, coauthor of Tara Romaneasca, and creator of several other free Twilight: 2000 and Twilight: 2013 resources.

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- General Eric Shinseki
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