[HT] Explosive Reactive Armor: Part II

[General Lee]

Hello, folks.

Some time ago, I started a thread about Explosive Reactive Armor (right, right I misspelled it, here).

Despite the effort, I still have some doubts about how ERA works in game.

Recently, I come to play with armored vehicles again and the question about ERA armor came up one more time.

But, this time I do some research and give a new thought.

For starts, I found (ok, one I already see here in this forum quoted by Douglas Cole) two sites of huge help about this topic.

This have RHA estimatives for modern tanks: http://collinsj.tripod.com/protect.htm

And this, explain how a reactive armor works, and give an estimate for RHA equivalent armor for Kontakt-5 ERA that is both effective against chemical rounds (HEAT, HEADP) and Kinectic rounds (APFSDS). http://www.russianarmor.info/

On this last site, I found that Kontakt-5 have RHAe of 250mm (DR 700) vs Kinectic and 600mm (DR 1680) vs Chemical.

Now, the problem: Only MS-HEAT could inflict damage to vehicles when these have ERA armor or not? For example, a Leopard 1A5 ( Turret DR 1260 [against HEAT/ RHAe 450mmm) with ERA ( plus DR 700/ 250mm [based on ERA used in M60 A1] would give a total DR 1960. So a HEAT missile that does more than 560d [7dx8(10)] with one warhead would still penetrate?

[Ulzgoroth]

Are you asking whether ERA makes it strictly impossible for HEAT to penetrate? It assuredly does not do that. A sufficiently large HEAT warhead can punch through spaced or reactive armor. It's good protection, not a shield of invulnerability.

[Nereidalbel]

Good rule to live by: if something is not 100% immune to a damage type, all you have to do is hit for more than total DR to injure/damage your target.

[General Lee]

Originally Posted by Ulzgoroth

Are you asking whether ERA makes it strictly impossible for HEAT to penetrate? It assuredly does not do that. A sufficiently large HEAT warhead can punch through spaced or reactive armor. It's good protection, not a shield of invulnerability.

No. I'm not asking it, but given the way ERA works, if one warhead could have its efficiency reduced. For example, the tip of the jet disrupted, not given full damage.

[Ulzgoroth]

Originally Posted by General Lee

No. I'm not asking it, but given the way ERA works, if one warhead could have its efficiency reduced. For example, the tip of the jet disrupted, not given full damage.

Yes, of course, that's why the ERA provides DR at all

[General Lee]

Originally Posted by Ulzgoroth

Yes, of course, that's why the ERA provides DR at all

Sorry. Let me rephrase it.

ERA works by disrupting the molten jet of HEAT. OK.

But, when not using a MS-HEAT, a given ERA armor degrade perfomance of a HEAT warhead or this effect is already factored in on the RHA estimate?
And, more, after passing through an ERA armor the armor divisor (10) still aplies for the main armor?

[Tzeentch]

Originally Posted by General Lee

But, when not using a MS-HEAT, a given ERA armor degrade perfomance of a HEAT warhead or this effect is already factored in on the RHA estimate?
And, more, after passing through an ERA armor the armor divisor (10) still aplies for the main armor?

-- In GURPS? ERA is a bit complicated both in actual use and in game rules -- the older rules are really only applicable to Gen1 ERA like Blazer. (Note: Don't have the books in front of me). But the ERA DR is the performance degradation (it's a reasonable abstraction). MS-HEAT should have a follow-on attack that ignores the ERA DR. I believe this is spelled out in High-Tech?

[General Lee]

Originally Posted by Tzeentch

-- In GURPS? ERA is a bit complicated both in actual use and in game rules -- the older rules are really only applicable to Gen1 ERA like Blazer. (Note: Don't have the books in front of me). But the ERA DR is the performance degradation (it's a reasonable abstraction). MS-HEAT should have a follow-on attack that ignores the ERA DR. I believe this is spelled out in High-Tech?

So, a powerful HEAT warhead could defeat an ERA + main armor combination.

[General Lee]

Originally Posted by Tzeentch

-- In GURPS? ERA is a bit complicated both in actual use and in game rules -- the older rules are really only applicable to Gen1 ERA like Blazer. (Note: Don't have the books in front of me). But the ERA DR is the performance degradation (it's a reasonable abstraction). MS-HEAT should have a follow-on attack that ignores the ERA DR. I believe this is spelled out in High-Tech?

Indeed, High-Tech spelled it out. I see the light! MS-HEAT works as described in HT against "Gen1" ERA, exactly as you said. But, against more modern types of armor like "Advanced ERA" (NERA, NxRA, Heavy ERA [Kontakt-5]) or Passive Armor (laminated or Modular Ceramics [MEXAS, AMAP]), it works as a big single warhead against all armor.

Additionally, the "special" effect of the MS-HEAT, i.e, the second warhead ignoring the ERA DR, is achieved only if the first warhead defeated the ERA layer. For example, an ERA armor that gives 250mm RHAe (DR 700) is supposedly defeated by a warhead that does 6dx4(10).

As the more modern ERA armor gives high levels of protection (DR 1,200+), the first warhead of a MS-HEAT round have to practically do damage of a full warhead 8dx5(10) to defeat the outer layer.

The real issue is to gauge how effective is a given type of ERA armor, actually any type of armor.