Capital Missiles v. AMS Rules Interactions and Design Implications

[marcussmythe]

By my understanding:

32 AMS will kill one Kraken-T, if assembled in one bay. (Due to rounding - 96 is 9.6 rounds to 10, dead Kraken missile)

Under the most recent ruling, that single bay of 32 AMS may freely engage, as separate targets, each incoming missile, even if those missiles are coming from a single bay.

A hypothetical attacker with 10 bays each bearing 7 Krakens, firing 70 missiles at the above target, will generate 0 hits, with every missile automatically destroyed (assuming the target is not heat or ammunition limited - we assume anyone bothering to put 32 AMS on a unit will install sufficient ammo or freezers, and such ammo or heat sinks are still a relatively small investment, compared to that of the attacker)

Thus, if the above is correct,  capital missiles as a weapon against capital ships are only a thing until the designers decide they are no longer a thing (and do so at a mass cost which is trivial in warship terms - the cost of putting 32 AMS on fore/after/broadsides, reserving F and A sides for your capital weapons, is trivial)?

Am I understanding this correctly?  This seems to be an odd choice by the rules writers.

[Liam's Ghost]

You're reading it right. The only limitations are the heat capacity of the defending ship and the ammo load of the AMS.

Though that's still a bit more tricky than one might think. Those 32 AMS count for fire control tonnage, meaning they'll up the mass of your entire weapon load in each arc where they're mounted.

For standard AMS, you also have to make sure you have enough ammo. That may seem simple enough, but it's entirely possible for a warship to face swarms of over a hundred missiles or more, depending on the opponent (fighter groups can carry a lot of external ordnance). So each bay of 32 AMS might burn through upwards of three or four thousand shots in one battle. Also, you can't share ammo among different bays (as far as I know), so each bay has to have enough shells to handle the whole engagement, just in case the enemy is able to concentrate on one direction of attack.

Laser AMS obviously don't use ammo, but they have a much higher heat debt you have to meet. 224 per bay per missile engaged (assuming a bay of 32). Unless you're carrying tens of thousands of heatsinks, it's entirely possible that a large enough missile swarm can overwhelm your ability to repel it, especially if you've already fired other weapons on that turn, or intend to fire when your turn comes up.

This also dictates the tactics the missile player might use against you. If you have standard AMS, then the enemy can just lob a few missiles at a time at you to reduce your ammo stores. While if you have laser AMS, they need to hit you all at once to really degrade your defenses. This usually means that laser AMS is better for defense against capital missiles (since ships generally don't carry enough missiles to actually overwhelm a well designs Laser AMS battery) while standard AMS works equally well against both capital missiles and fighter launched ordnance.

Of course, all the weaknesses of AMS can be overcome by just throwing tonnage at the problem, but that might not be entirely feasible on smaller hulls.

[marcussmythe]

I usually find myself, given my ‘druthers, isolating the anti-fighter/anti-missile battery from the anti-ship batteries, thus the huge cost in fire control for a 60+ weapon array on a facing is applied only to the (light at warship scales) normal scale weapons.

Fore and Aft sides get the anti-ship guns, 20 per facing.

The question came up out of a thought experiment - given their (relatively) low launcher weights, can one mass a large number of capship missiles on a facing (by themselves, away from the huge modifier of the PDS facing and not inflating the cost of the NAC/NPPC facing.  And the answer I found was ‘yes you can and its bloody terrifying’... right up until someone mounts 1x32 (or 5x25) AMS and enough heat sinks.

Though as I do the mental math, the heat debt of blowing away that missile swarm, over 14K, is enough that the cost to even an optimized battleship design is no longer trivial. 

[Alsadius]

Yeah, the AMS rules are awful when combined with custom ships. If you're limited to canon designs then AMS is reasonable, but if you can add your own AMS freely, then capital missiles are garbage. It's vastly cheaper to knock them down than it is to send them out, and the entire weapon class
effectively dies off as a result.

For a simple change, how about something like this?
- Only AMS systems can be used for point defense.
- Each AMS can only fire once per round, but a hit will kill any missile.
- Unlike most weapons, PD bays do not need to fire together - they're grouped for convenience. The defending player may divide up their PD against any number of missiles as they see fit.
- It takes 10+ to hit a Kraken, 9+ to hit a Killer Whale, 8+ to hit a White Shark, and 7+ to hit a Barracuda or any sub-cap missile, if they are aimed at your ship. If they're just flying by, a +2 penalty applies.

That should allow point defence to be installed in useful quantities without just deleting a weapon class.

If you want to be a bit more ambitious, try these rules:
- Regular PD can only be used against standard-sized missiles.
- A new Capital AMS weapon is added, which weighs 50 tons, has 5 shots per ton of ammo, and generates 10 heat every time it is fired.
- A Capital AMS can fire multiple times per turn. However, if two or more shots per AMS are fired, roll 2d6 - if the roll is less than or equal to the number of shots fired, the weapon jams on that round and cannot be used thereafter. (E.g., if the player attempts to fire six shots, they roll 2d6. If the roll is a 5, then the first 4 rounds fire normally, and the weapon jams on the fifth shot. 60 heat is generated, and the weapon is unavailable for the rest of the scenario)
- As above, bays do not need to be fired together - the player may choose to divide bays between attacking missiles as they see fit.
- Capital AMS automatically hits any missile targeted that passes within Short range(capital-scale) in the appropriate firing arc. One hit kills a Barracuda or any sub-cap missile, two for a Killer Whale, three for a White Shark, or five for a Kraken.

That should provide a more plausible defensive system. You can go all-out to deal with a giant salvo, or play it safe and degrade enemy fire somewhat while keeping your AMS around for future rounds. It may take up a bit too much time/effort for players who don't want to focus on this part of gameplay, but I think it'd be interesting and fun.

[marcussmythe]

For a simple change, how about something like this?
- Only AMS systems can be used for point defense.
- Each AMS can only fire once per round, but a hit will kill any missile.
- Unlike most weapons, PD bays do not need to fire together - they're grouped for convenience. The defending player may divide up their PD against any number of missiles as they see fit.
- It takes 10+ to hit a Kraken, 9+ to hit a Killer Whale, 8+ to hit a White Shark, and 7+ to hit a Barracuda or any sub-cap missile, if they are aimed at your ship. If they're just flying by, a +2 penalty applies.

That should allow point defence to be installed in useful quantities without just deleting a weapon class.

Headcannon accepted.  Looking at Krakens (the extreme case), youve got basically 1 in 6 for a single PDS to kill a Kraken.  4 PDS get you to a 50/50 level, but no sane number of PDS will get you past one in 10 getting through.  (Assuming a Look-Shoot paradigm.  As soon as we move to look-shoot-look-shoot levels of PDS, the match changes radically.  Hmm.  Maybe implement a slightly longer ranged 'capital' PDS that can fire off first, followed by 'normal' PDS?  What if we start shooting at Capital Missiles with small sup-capital missiles?

[Tai Dai Cultist]

I'm not sure if it's also true about WarShips, but at the DropShip/Small Craft level the rules do apply a penalty for loading up on AMS systems.  You've got a limit of 12 weapons per bay, and you suffer tonnage penalties to all weapons in that bay if you bust the limit.  AMSs can still get away costing 10%, 20%, even 30% more tonnage but when you consider that applies to ALL weapons in that bay it can get untenable for anything other than a dedicated AMS porcupine/fleet defense type unit.

[marcussmythe]

Tai Dai Cultist - those modifiers absolutely apply once a Capship goes over 20 mounts on a facing.  The ‘solution’ inasmuch as there is one is to isolate capship weaponry on the fore and rear sides, while concentrating anti-fighter/point defense on the broadsides, front, and rear.  Point Defense and Normal scale weaponry has negligible mass on a capship, and even doubling or trebleing that mass by requiring massive fire control mass (at 120 weapons and 220 weapons repsectively) doesnt make it all that heavy.  When one considers that much of the ‘mass’ of a L-AMS, ERLL, or ERPPC (much less a capacitor fed one) is in its heat sink requirement, the effect becomes stronger.

[Alsadius]

If you want to be really cheesy, use fore/aft/LBS/RBS for PD and anti-fighter weapons - they cover the full 360 degrees perfectly. Isolate capital weapons in FR/FL/AR/AL, which cover everything except the row of hexes directly fore and aft, and still allows for two facings worth of damage on the broadside. That way you can load up on porcupine guns of various sorts, get perfect coverage with countless hundreds of guns for no meaningful weight penalty, and still have 80 slots for capital mounts.

The WarShip rules...well, let's just say, they're prone to abuse in their current state.

[marcussmythe]

I think its a problem growing out of the super-tight (and super silly) fire control restrictions.  The idea that 100 PDS sharing the same kilometer-long broadside of a Capital Ship would demand that a nearby Heavy NGauss mount its own mass again in fire control really strains credulity, especially while those same 100 PDS moved an extra few hundred meters aft would not only weigh less, but avoid doubling the mass of the NGauss in question.  The fire control rules are an obvious (and ineffectual) attempt to reign in 'forget cap weapons, I'll just mount 10000 ERPPCs' - brought on by the inherit problems of allowing machine guns to pierce battleship main belts.

For my 2C-Bills, doing a fore/aft/broadsides PDS with a Front Sides/Rear Sides Capship Battery is really little different than 'not leaving AC/5 ammo alone in the side torso of your Marauder' or 'stop adding heat sinks once your mech cant overheat on a jumping alpha' or 'yannow, armor is light, maybe we should use more'.  Most of the Warship designs are essentially in the same state as the original unseen designs - naive to both the construction rules and the play environment they function in. 

[Daryk]

Ok, the title finally got to me... you can edit the thread title by simply "Modify"-ing  the original post.  In the mean time, I recommend responders fix the "k" to an "l" in the title before hitting "Post"...

That out of the way, I agree with TDC... the ultimate solution here is multiple hulls.  Dedicated AMS platforms with minimal anti-anything else weaponry escorting your ASF defense and Anti-WarShip platforms would be a hell of a fleet to face...

[Tai Dai Cultist]

..Most of the Warship designs are essentially in the same state as the original unseen designs - naive to both the construction rules and the play environment they function in.

That's absolutely true.  It's impossible to be otherwise as the bulk of the WarShip designs in canon predate the current construction rules (TM/SO).  The Star League era WarShips even predate multiple construction rule-sets as they debuted all the way back in TRO:2750.

BattleTech has never gone back and re-jiggered previously canon designs to update them for new iterations of the rules.  The WarShips just remain nonsensical.  IMO it's also why you shouldn't allow custom WarShips in a campaign; ships built to take advantage of the current construction rules just have that inherent advantage over the corpus of canon classes available.  (for a meta example, see the Lev III)

[marcussmythe]

Well, I'd view letting 'Custom Warships' loose in a campaign the same way Id view letting 'Custom Mechs' loose on a campaign that otherwise only featured the Unseen.

One thing that saddens me (as an inveterate builder and fiddler) is that the modern capship design space is so constrained - noones building the things, and if you modify a faction to start building them, or add a faction, your already off in AU territory.  Not that I let that stop me...

[Tai Dai Cultist]

That being said, the mech construction rules have largely passed through the years intact.  What changes there have been are both few and minor.

That's not true on the Aero side of the house.  Entire construction rules have been thrown out completely (twice!) before the current version.  Old mechs from the 1980s may not have all the same design paradigms in mind as those published today, but the rules are compatible and the mechs are at least playing the same game (literally).  WarShips from the 1980s aren't.  That's why they appear so silly under the existing rules... it's from 2+ generations preceding the current one.

[Starfox1701]

Yeah, the AMS rules are awful when combined with custom ships. If you're limited to canon designs then AMS is reasonable, but if you can add your own AMS freely, then capital missiles are garbage. It's vastly cheaper to knock them down than it is to send them out, and the entire weapon class
effectively dies off as a result.

For a simple change, how about something like this?
- Only AMS systems can be used for point defense.
- Each AMS can only fire once per round, but a hit will kill any missile.
- Unlike most weapons, PD bays do not need to fire together - they're grouped for convenience. The defending player may divide up their PD against any number of missiles as they see fit.
- It takes 10+ to hit a Kraken, 9+ to hit a Killer Whale, 8+ to hit a White Shark, and 7+ to hit a Barracuda or any sub-cap missile, if they are aimed at your ship. If they're just flying by, a +2 penalty applies.

That should allow point defence to be installed in useful quantities without just deleting a weapon class.

If you want to be a bit more ambitious, try these rules:
- Regular PD can only be used against standard-sized missiles.
- A new Capital AMS weapon is added, which weighs 50 tons, has 5 shots per ton of ammo, and generates 10 heat every time it is fired.
- A Capital AMS can fire multiple times per turn. However, if two or more shots per AMS are fired, roll 2d6 - if the roll is less than or equal to the number of shots fired, the weapon jams on that round and cannot be used thereafter. (E.g., if the player attempts to fire six shots, they roll 2d6. If the roll is a 5, then the first 4 rounds fire normally, and the weapon jams on the fifth shot. 60 heat is generated, and the weapon is unavailable for the rest of the scenario)
- As above, bays do not need to be fired together - the player may choose to divide bays between attacking missiles as they see fit.
- Capital AMS automatically hits any missile targeted that passes within Short range(capital-scale) in the appropriate firing arc. One hit kills a Barracuda or any sub-cap missile, two for a Killer Whale, three for a White Shark, or five for a Kraken.

That should provide a more plausible defensive system. You can go all-out to deal with a giant salvo, or play it safe and degrade enemy fire somewhat while keeping your AMS around for future rounds. It may take up a bit too much time/effort for players who don't want to focus on this part of gameplay, but I think it'd be interesting and fun.

A few changes
1st make it 100 tons
2nd 6 shots per tone of ammo
3rd jams take 1 turn to clear, it is a warship she will have damage control and gun crew
4th she can only fire 6 times per turn
5th each hit does d6 damage
6th number of shots and there intended targets must be declared at the time of firing.
7th shots don't autohit but use same base role as all other weapons but never have any modifiers.
8th whem calculating the max number of weapons in a bay use the max possible damage ie 6

[Col Toda]

People seem to be missing the point . AMS is just one system point defense system .  The 32 AMS is grossly wasteful and sloppy . The basic premise of point defense is to reduce an incoming salvo of normal missiles below the armor threshold number. I tend to go with 2 bays of AMS portionate to the size of the ship and use rear and forward firing IS small pulse lasers or Machine guns on fighters as dou purpose equipment . AMS can only be used for point defense and nothing else . Also have the dropship have ECM escourted by 2 fighters or smallcraft with ECM . If it does not hit in the first place is a far better defense and the ECM actually helps against direct fire . From my perspective if someone wants to piss away too much on AMS It is there own lookout .  Nothing is wrong with the existing rules . Only very slow units with tight fuel constraints should even contemplate huge a AMS bay as they would disproportionately suffer from criticals of capital missiles . Most canon designs do not have enough armor and ams so what you are seeing are people overcompensating . The lack of balance of such tends to come up sooner rather than later . The new style pocked warships with sub capital direct fire weapons tend to eat such for lunch particularly in concert with navel c3

[marcussmythe]

Nothing meaningful is ‘pissed away’ in mounting 32 or so AMS on four facings along with the low mass anti-fighter weapons.

[Col Toda]

Ok lets see 32 Heavy Machine Guns if Clan uses half the fire contol mass ,  produces No heat . uses less than a half ton of ammo . And should no missiles be available to shoot 96 points to a passing fighter at close range .  AMS uses less than 3 tons of ammo when used and produces 32 heat . Yes to work as point defense it has to be set for point defense . Now laser point defense does 5 per unit and 7 heat sinks which means small craft and drop ships that have a lot of free heat sinks for having a massive engine may be a better way to go . And low mass anti fighter weapons are always a good idea . Sorry I did not make a clearer argument in my last post . But almost no one uses optimal weapon choices in Aerospace . The initial point of the post is very valid pre 3075 . My only observation is pocket warships move from capital missiles to sub capital direct fire weapons and the unit mounting 32 AMS will work great at the rare salvo heading your way . Having less fire control heat sink and ammo tonnage lets you add SI and armor or even heavier hitting weapons and heat sinks for the best defense is a better offense . Is the opposition force your still facing shooting missiles at you ? For me long range direct fire heavy weapons with Navy C3 gets ugly .  Say 4 pocket war ships have a bay with 5 light gauss rifles doing 4 / 40 points of damage 3 of them are at extented range one at short range navel c3 give them all short range . That is just a normal inner sphere weapon choice . Sub capital weapons can make it far worse . The DC has a pocket warship with enoungh sub capital auto cannons to make real war ships take notice .

Aerospace combat paradigms have shifted .  That is the very big point I was trying to convey when I said those who invest too much in AMS is their lookout . By rights they should be 9 - 12 blocks or generations of ship design given the centuries in the game and it is far less than 5 . Stay out of the post Jihad ERAs and your position will be correct more often than not .  Almost any answer to every question in battltech is ERA dependant.

[Lagrange]

HMGs cannot fire repeatedly and only do half damage in point defense mode. 

[Col Toda]

Ok so heavy mg uses the same Fire Control tonnage and 1 ton still less than 3 + tons of an AMS l) . It is a toss up use once with no heat use more than once at 32 heat a pop . My point on paradigm shift remains If you are being shot at with missile weapons 1/10th the time than you were in a previous era . Shooting repeatedly is less relevant . AMS should be included on many desgns along with Heavy Machine Guns . Just strike a balance that optimizes available heat dissapation and tonnage available . Normal missile salvos and the rare sub capital missile become the norm and the Capital missile the outlyer .  How much are you going to invest on an uncommon event .