Valiant vs Avalon

MuonNeutrino wrote:

Weird Harold wrote:Why does everyone assume that the Avalon NEEDS Mk-16s to be effective?

Point one: The Avalon was designed and built concurrently with Rolands and Sag-Cs. Obviously the designers had access to MK-16s and did not uses them. They didn't even opt for ERMs, going for Light Extend Range Missiles (LERMS)

Point Two: As I proposed in the build-a-bear thread, smaller DDMs using capacitors and relying on a ballistic phase for extended range is theoretically possible. Why not build light combatants around a smaller DDM than the MK-16?

Point Three: Navies didn't design destroyers and light cruisers around 18 inch main guns, they designed them for 5 inch guns or 8 inch guns.

Note that while the original Avalon is a contemporary to the Roland and Sag-C, House of Steel notes that it's actually based off the Saganami-B generation of designs. That means that it's a pre-Mk16 design.

And yes, the LERM is a nice missile. It's also completely outclassed in every way by the Mk16, and units carrying it are only viable as long as they're not fighting anything with Mk16 equivalent capability. The original Avalons are fine for the pre-MDM threat environment, but they'll be thoroughly obsolete in the future environment after MDMs have proliferated beyond the alliance. The 'Avalon successor' designs people are pondering are really the CL version of the Roland or Sag-C, designs intended to (or at least attempt to) be viable combatants in the era of MDMs.

It may well be that there will eventually exist some kind of smaller MDM than a Mk16 for the lightest combatants, but so far I haven't seen any sign that one is on the boards anywhere or would be capable enough to actually be worth it relative to a Mk16. No offense, but capacitor-fed DD/CL-weight missiles that get their extended range just from a ballistic component (e.g. reach their final range at a *vastly* lower velocity/longer flight time than a true MDM/DDM) and don't have the fusion plants to feed modern high-power EW don't seem to me like they'd be effective enough to justify using unless they were literally half the size of a Mk16 or smaller.

As far as Naval analogies, I would consider it a mistake to put too much stock in them. The honorverse may well be designed to evoke the age of sail and/or the age of the battleship, but it's not *actually* those eras. And even if you did want to, IMO the MDM/DDM are not analogous to the big guns, they're more analogous to the guided missile revolution. And even if they *are* the big guns, the Mk16 isn't the 18" - that's the Mk23 and/or Apollo, the Mk16 is a smaller gun.

My personal opinion is there was no acceptable Sag-C CL consort design. When the 2nd war started (or was heating up) the original build tranche was of the ERM ships. As the Mk-16 ships replaced them in the 2nd build tranche, no mk-16 CL design was available. As I pointed out earlier, the only 2 options to build such a design are a modified Roland arrangement, with the compromised main battery, and a design with a Sag-C beam, which would make it slowish and take up a Sag-C build slip, while costing a fair % of a Sag-C.

So in Lieu of a better, workable design, they just continued building Avalons while planning for the next, better ship design. Especially since the Avalons currently outgun and outrange any competitor first line CA, meaning that the Avalon will not we obsolete for many years to come, thouh sooner than the Mk 16 ships. If I were the RMN I would be working on a 180 degree offbore capability upgrade for the Avalon (and Wolfhound, Kamerling, Sag-B and Reliant III/IV) to continue this superiority as long as possible.

Harold, I can see the...elegance of your proposed missile design, but I don't know if it would be workable, 2 capacitor stacks, even limited ones, plus 2 drives could easily push your proposed idea into ERM or Mk 16 territory, despite the smaller warhead. Perhaps 2 Mk32 CM drives + a DD warhead would be the way to do it. Or maybe we will see a 2 drive Viper variant.

8 inch guns were usually the definition of a CA, but you do make a good point, The only reason the Roland has Mk 16s is it is the smallest DDM the RMN fields atm. The Roland design MAY have been thought of as a CL at some point, due to it's size, but it's lack of true multi-role capability got it branded as a DD.

The problem with innovative designs is that you sometimes end up with the Little Crappy Ship as the final product. Or the the Navy's newest carrier, ending up with critical pieces taking years longer than planned. So when you are at war having a backup conservative design that should just work might seem like a good idea.

Theemile wrote:Harold, I can see the...elegance of your proposed missile design, but I don't know if it would be workable, 2 capacitor stacks, even limited ones, plus 2 drives could easily push your proposed idea into ERM or Mk 16 territory, despite the smaller warhead. Perhaps 2 Mk32 CM drives + a DD warhead would be the way to do it. Or maybe we will see a 2 drive Viper variant.

You wouldn't need two capacitor stacks, just exchange pre-war capacitors for Manticore's super-dense capacitors on a one-for-one rate. Extend the missile or trade capacitors for missile drive + baffle. The end result should have the same powered range as the SDM it is derived from and could fit in the same tubes as the SDM parent missile.

If you're designing an "Avalon-B" around a new missile instead of a fusion-powered Mk-16, you have a lot more "fudge-room" in making a LDDM (Light Dual Drive) or CDDM (Cruiser Dual Drive) missile.

Adding the same upgrade as a Mk16's "Mod G" warhead, to ERM warheads or LERM warheads (or design a completely new Mod-G style warhead for an entirely new missile for an entirely new ship) and you get most of the killing power of a Mk-16 in a smaller package. The only thing you'd be giving up is powered range and/or terminal velocity.

Since Avalon's aren't built for offensive power in the Fleet Engagement Context but are anti-missile and Anti-LAC screening units, range and terminal velocity aren't big considerations. In the independent cruising role, terminal velocity isn't going to be a big factor since any opponent where that is going to be decisive is a "run-for-your-life" opponent anyway.

Henry Brown wrote:To me the puzzlement is why the RMN kept building Avalons. Current RMN tactics focus almost entirely on long range missile fire. CLs are the only class of ship that does not adhere to this (other than LACs).

A bigger question is why build any Wolfhounds, which are only very marginally smaller and cheaper. Heck, if you don't, and designate the Avalon as the DD and Roland as the CL, things are a bit less confusing.

(Apologies in advance for the wall of text...)

As best as I can tell, the LDDM idea actually might be possible (unlike a lot of crazy ideas that have come through these forums!), albeit it's hard to pin down exactly what level of performance it should be capable of. The real question IMO is whether it'd be worth it compared to the Mk-16, and my guess is probably not in most cases.

The big unknown is how much internal volume the second drive ring (and any necessary internal drive components that also have to be duplicated) would take up. It's gotta be at least *some* volume, but if it's small enough then you might be able to pay for it by slightly reducing capacitor volume (e.g. probably bringing the endurance down from Mk-36 LERM levels back to 'standard' SDM levels - note that the LERM *has* to have more energy dense capacitors than pre-war missiles to power its longer running drive, so you can probably do this), especially if it's possible to make the drive components themselves any smaller given that each drive ring only has to run for half as long.

Under the optimistic assumption that you can make those tradeoffs, the net result would be a missile the size of a Mk-36 LERM (which is a DD/CL size missile as opposed to the CA/BC sized Mk-16), that can either just run both drives in succession for the same acceleration and total powered endurance as a standard single-drive missile (e.g. slightly shorter than a LERM), or run one drive for half the time of a SDM, coast, then turn on the second drive once it gets close to its target, for the same terminal velocity as a standard SDM but longer powered range due to the coast phase. Warhead would be equivalent between the two missiles (any upgrades could be just as easily applied to the LERM as well), so that's not really important for the moment.

The real question is, *are the tradeoffs relative to the Mk-16 worth it?* That is, are the hypothetical advantages in number of tubes mounted, internal volume used, number of missiles that can be stored, etc, worth the undeniably decreased effectiveness on a per-missile basis? This is, unfortunately, the place where it becomes difficult to draw any definitive conclusions. We can try to parameterize the various differences, though.

First, we can assume it'd have the standard acceleration numbers, so 46,000 G (450.8 km/s^2) at the usual low power long range drive settings. Under this design it would have two drive stages of 90 seconds each, rather than one of the usual 180 seconds. The first stage will accelerate it to 40,572 km/s over a distance of 1.83 million km, and the second stage will accelerate it up to a terminal velocity of 81,144 km/s (or 0.27 c) over a distance of 5.48 million km, for a total (continuous-burn) powered range of 7.3 million km (or 24 light-seconds) from rest. Now, we're going to assume that the targets are farther away than that, just because otherwise the entire topic of extended range missiles is moot. To reach a more distant target will require a coast phase between the first and second stages, which at 40,572 km/s will add 30 seconds to the flight for every additional 1.22 million km of range.

Meanwhile, a Mk-16 accelerates at 46,000 G for two consecutive 180 second drive stages, reaching a final velocity of 162,288 km/s (0.54 c) and covering a distance of 29.2 million km (~97 light seconds) in the process. If it uses the second stage at full power instead, after 240 seconds of acceleration it'll reach a final velocity of 135,240 km/s (0.45 c) over a range of 13.8 million km (~46 light seconds). (This is a lower terminal velocity than the final velocity of a *full* double low power burn, but if the target is at 13.8 million km or closer it'll be faster than the *abbreviated* double low power burn needed to reach that range.)

To reach the 29.2 million km powered range of a Mk-16, a LDDM will have to coast for 538 seconds before kicking in its second drive. At 500 gravities, a target ship could change its predicted position by about 0.7 million km during that time period, which is not really enough to make it impossible for the missile to catch up to it but definitely would lower accuracy. Total flight time will be 718 seconds, or almost 12 minutes, and terminal velocity will be 0.27 c. Meanwhile, as noted above, a Mk-16 makes the same trip in 360 seconds, and will have a terminal velocity of 0.54 c. Comparing the 13.8 million km snapshot case, the LDDM will have to coast for 160 seconds, for a total flight time of 340 seconds and the same terminal velocity of 0.27 c. Again, as noted above the Mk-16 will make the trip in 240 seconds and will have a terminal velocity of 0.45 c.

Overall, the LDDM doesn't come off as bad as one might expect in terms of raw range/flight time. Yes, it will usually take 40-100% longer to get to its target than a Mk-16, at a consequent loss of accuracy, but it can still get there in not completely unreasonable lengths of time. However, where it falls down badly is in terminal velocity, with Mk-16s generating roughly double the velocity in most cases, and I think you're severely underestimating how important that is.

At the most basic level, terminal velocity directly determines how long their missile defenses get to shoot at each of your birds - to first order, twice the terminal velocity means half as many CM and PD shots at each missile, and assuming everything else is equal means half as many birds get shot down. (In practice, we've seen that higher terminal velocity also lowers the chances of each CM/PD shot actually hitting its target, so twice the terminal velocity equates to *less* than half as many birds getting shot down.) Really, the terminal velocity allowed by the DDM/MDM format is almost as important as the range - even with their EW, that terminal velocity still accounts for a large chunk of the amazing ability modern manty missiles have to penetrate missile defenses. Even against defenses that know that kind of speed is possible, it still cuts defensive engagement time by 1/2 to 2/3rds - and it does so regardless of the defenders point defense accuracy/ability to see through your EW.

Honestly, the advantages of increased terminal velocity are going to be most decisive not against a grossly superior tonnage of foes (which will have enough missile defense to swat your small salvo even if they only get one shot, if they're not completely incompetent - and you can't design your fleet assuming incompetent foes), but against near-peer opposition whose missile defenses are closer in overall capacity to your salvo sizes. Going from the enemy being able to shoot your entire salvo down thrice over to being able to shoot it down only 1.5 times over doesn't make a difference, but going from them being able to shoot down 80% of your salvo to only being able to shoot down 40% of it is a *huge* advantage. In other words, this advantage will be most important against exactly the foes the ship will most need an advantage *against* in that independent cruising role - near-peer foes.

Now, one might argue that the lower ability to penetrate missile defense would be compensated for by the larger number of missiles you'd be able to throw in each salvo, given that you can afford to mount more of the smaller tubes, but that brings us to the *rest* of the advantages that the full-up DDM Mk-16 has - namely, damage potential and EW.

Regardless of upgrades, not only is a LDDM's warhead still going to be considerably weaker because the space to cram in a warhead is much smaller, it's also going to have to have shorter (and possibly fewer) lasing rods, again just because the missile is smaller. I would be very surprised if a LDDM hit could deal more than half as much damage as a Mk-16 hit, and I would definitely not be surprised if it were more like a third to a quarter. (Note that even assuming equal sizes/numbers of lasing rods and grav lens effectiveness, this DD/CL weight missile would have to have a 20 megaton warhead - bigger than the 15mt warhead in the original CA/BC weight Mk-16! - in order to do even half as much damage as the current Mk-16 with 40 megaton warhead. Even assuming it can get that big of a warhead, the fewer/shorter lasing rods will definitely further reduce its power.) And the other major drawback of the LDDM format is that it's penetration aids are going to be greatly inferior to those of the Mk-16, because of the much greater power made available to Mk-16 EW heads by their microfusion reactors. We've seen described many times in the books just how amazingly nasty microfusion-powered EW is compared to traditional penetration EW, and I think it's safe to say that the difference in effectiveness is *at least* enough to counterbalance the lower numbers of EW birds you'd have in each salvo, and perhaps even to still be more effective.

Ultimately, to put it all together, Mk-16 salvoes are likely going to be at least twice as good at penetrating enemy missile defenses due to their velocity, penetration EW is at *best* a wash and likely still in the Mk-16s favor, and each hit is going to be at least twice as damaging due to their superior warheads and lasing rods. That argues that, in order to be equally effective, you need to be able to throw something like four times (or more) as many LDDMs. Are LDDMs and their launchers going to be only a quarter the size of Mk-16s and *their* launchers? I don't think we have any way of saying for sure, but I'd bet no, and so I'm guessing that for something the size of an Avalon-B successor Mk-16s are still going to be better. (Mk-16s would also require less fire control.) However, if you're talking something small enough that you just can't mount Mk-16s *at all* (like a Wolfhound), then a LDDM might be useful, though at that point you have to weigh their performance against a Mk-36 LERM instead and I unfortunately don't know what the numbers are for that missile.

(Also, side nitpick - Avalons aren't built for *any* role in the Fleet Engagement Context; the RMN has pretty much concluded that DDs and CLs are far too vulnerable targets to have any business in a wall of battle engagement and their fleet screening role has basically reverted to the much more elusive, expendible, and effective LACs. Irrelevant to the rest of the post, just wanted to note that.)

MuonNeutrino wrote:(Apologies in advance for the wall of text...)

As best as I can tell, the LDDM idea actually might be possible (unlike a lot of crazy ideas that have come through these forums!), albeit it's hard to pin down exactly what level of performance it should be capable of. The real question IMO is whether it'd be worth it compared to the Mk-16, and my guess is probably not in most cases.

...

The LDDM was originally proposed as a replacement for the LAC/DD and/or LERM. A Cruiser weight, or CDDM, replacement for the ERM would be needed for a hypothetical "Avalon-B." IIRC, the ERM carries the same warhead as the original Mk16 and would get the same benefit from improved grav lensing and/or a "Mod-G" warhead.

The rest of your argument regarding Terminal Velocity would apply to comparing Mk16G with Mk23 or Apollo system defense. They're slower and less awesome... and every ship should have the fastest and awesomest missiles available.

The whole point of a LDDM or CDDM is to provide smaller ships with enough range and tactical options to match Cataphract armed "Peer" opponents. They aren't intended for ships to fight opponents that need A Mk-16 or bigger to kill them -- even though a CDDM should have a comparable warhead.

One argument against matching Mk-16 performance is the argument used for loading Mk16 pods in BC(P)s like Agamemnon -- it removes the temptation to "fight above your weight." LACs, DDs and CLs should not be fighting CAs and bigger; they should be running from them (and small/fast enough to get away.

I think one of the reasons the Rolands are considered "transitional" is that they're over-gunned.

There's no such thing as just a 'cruiser weight' missile - CAs and CLs fire different sizes. Traditionally, DDs and CLs fired the same weight of missile, and CAs and BCs fired the same (heavier) weight of missile, and it seems Manticore is continuing that, as House of Steel notes that the Avalon and Wolfhound both fire the Mk-36 LERM (which must therefore be a DD/CL missile). The regular ERM (I believe it was denoted as the Mk-14) is a CA/BC missile and was used by the Saganami-B. So no, an Avalon-B probably ought to have the LDDM version if you don't want to give it full-up Mk-16s. (And note that comparing the (canon) renders by Maxxq, a Mk-16 isn't actually *enormously* bigger than a standard CA/BC missile (the Mk-13 next to it). If you want to give the Avalon-B a CDDM based on a CA/BC missile like the Mk-14 ERM, it's going to have similar ammo constraints as giving it Mk-16s, even if the launchers themselves aren't as big. The question here is basically between LDDM and Mk-16, given that I see little reason *not* to use Mk-16s if you're using a CA/BC missile anyway.)

As for Mk-16 vs Mk-23, those actually don't generate much difference in their terminal velocity as long as you're inside the Mk-16s (quite generous) powered range. Both of them still outrange SDMs, the Mk-23 just outranges them more. A Mk-23 is also going to require even better fire control to generate acceptable accuracy when used beyond DDM range, which is why they'd be overkill for something like a cruiser that will rarely have need to engage at those ranges (and whose targets will rarely have the ability to fire back *from* those ranges), as you well know.

It's not that every ship should have the fastest and awesomest missiles available. It's that every ship should have the best missiles available *to most effectively do the job it needs to do*, taking into account tradeoffs in what missiles it can practically mount. It's not practical to mount Mk-23s on a cruiser, and it doesn't need them anyway, as the Mk-16 delivers very close to the same performance out to most ranges the cruiser is likely to need to shoot at. The difference in performance between the Mk-16 and Mk-23 for this platform is much smaller than the difference in performance between a LDDM and Mk-16, which is why there actually can be a question as to which of those latter two missiles is more appropriate.

I do agree that Rolands *are* overgunned. Cramming Mk-16s and their launchers into a 188 kt platform is kinda crazy, as witnessed by how much that limits their other capabilities. A sub-200 kt platform *ought* to have a DD/CL weight missile like the Mk-36 LERM or your LDDM - note that even the lightest, oldest CAs in House of Steel were still over 225 kt. But that doesn't necessarily mean that a *300* kt platform can't have Mk-16s - again, note that my hypothetical 300 kt Avalon-B is about the same mass as a Star Knight.

And yes, I agree that if you're fighting an opponent that you could *only* kill with a Mk-16 but not a LDDM, you're probably fighting something you *shouldn't* be fighting. But that's hardly the only time the Mk-16 would be helpful. As I pointed out, the Mk-16 is still grossly more effective than a LDDM *even against those peer opponents you're supposed to be fighting*. In fact, if you want to fight Cataphract armed opponents, that's actually a good argument for using the Mk-16, since the Cataphract possesses many of the same advantages it does in terms of flight time and terminal velocity. If your missiles take several minutes longer than the enemy's to reach attack range, then *your* fire control starts getting degraded due to damage (and tubes lost, for that matter) before you even send your final course corrections to your first salvo, and if you've got LDDMs and he's got Cataphracts then you're at a steep disadvantage when it comes to penetrating missile defenses due to the terminal velocity differences. Frankly I'd expect, all other things equal, a LDDM ship to lose convincingly against a cataphract armed one.

I wonder if there's an argument for creating a true DD/CL weight DDM. We don't know whether it'd be possible to miniaturize the microfusion reactors enough to jam them into a DD/CL weight missile body, but if so, it might give you the best of both worlds. Such a missile's launchers would be bulkier than the launchers for a Mk-36 LERM or a LDDM, but still far smaller and easier to mount than the launchers for a Mk-16, and the missiles themselves would likewise be bulkier than a LERM or LDDM but much smaller than a Mk-16. The warhead would be the same as a LERM or LDDM (including any potential upgrades), but it'd still have the full true DDM powered range and terminal velocity plus microfusion-powered EW, with salvo sizes and ammunition stowage significantly superior to a Mk-16 design and not that much worse than a LERM or LDDM design.

I actually like that idea a lot. It's basically the same thing that both the Saganami-C and Nike did, relative to their older predecessors (of similar designs - that is, ignoring the BC(P)). Both of them stuck with the same basic weight of missile - the CA/BC grade - but just upgraded it to a fusion-powered DDM once the transition to the CA(L) and BC(L) hull formats was made and the bulkier launchers could easily be accommodated. So, if you're upgrading the DD and the CL to DD(L) and CL(L) formats, why not upgrade *them* to fusion-powered DDMs based on their traditional DD/CL weight missiles, instead of trying to use the next size up CA/BC DDMs? Because really, what I've been arguing for here is that it ought to mount a true fusion-powered full DDM. That doesn't necessarily *have* to be a Mk-16 - that's just the only fusion DDM that exists. But if it's possible to make a fusion-powered DD/CL DDM, then that's probably the way to go.

kzt wrote:The problem with innovative designs is that you sometimes end up with the Little Crappy Ship as the final product. Or the the Navy's newest carrier, ending up with critical pieces taking years longer than planned. So when you are at war having a backup conservative design that should just work might seem like a good idea.

The Air Force once upon a time did this. The B-29 had a backup, the B-32 Dominator. There were three alternatives to the B-36. The B-52 had a backup, the B-60. (Well, there was also the Featherlight.) It's expensive, but it works. And sometimes you really needed the backup.

MuonNeutrino wrote:I wonder if there's an argument for creating a true DD/CL weight DDM. We don't know whether it'd be possible to miniaturize the microfusion reactors enough to jam them into a DD/CL weight missile body, but if so, it might give you the best of both worlds. Such a missile's launchers would be bulkier than the launchers for a Mk-36 LERM or a LDDM, but still far smaller and easier to mount than the launchers for a Mk-16, and the missiles themselves would likewise be bulkier than a LERM or LDDM but much smaller than a Mk-16. The warhead would be the same as a LERM or LDDM (including any potential upgrades), but it'd still have the full true DDM powered range and terminal velocity plus microfusion-powered EW, with salvo sizes and ammunition stowage significantly superior to a Mk-16 design and not that much worse than a LERM or LDDM design.

I don't think it currently is possible to shrink a micro-fusion plant any smaller that the Mk16's. That will change eventually and even fusion-powered CMs and Vipers will be available. LDDMs are an interim design to give dual drive tactical options to legacy ships (and new design smaller ships) without requiring extensive modifications.

As originally conceived, LDDMs were also a second tier, non-GA, missile for LACs in the system defense role.

The main advantage of the LDDM design is that it is doable NOW and in a package roughly compatible with existing launchers. It doesn't require extensive cofferdams or new technology.

LDDMs and CDDMs are not as capable as Mk-16's but they are more capable than the capacitor missiles they are based on. They give ships armed with LERM and ERM missiles an option of dual drive tactical flexibility without the need to drop down a warhead size as the Cataphract design does or extensively modifying existing ships.

Finally, the LDDM concept was initially conceived as an export missile for export LACs by a former OFS sector economy. I'm sure that Manticore would improve on the idea before deploying it in the RMN.

One last thought: RMN warheads are bigger, more powerful on a missile class basis. Especially since the development of the Mod e(1)/Mod-G warheads for the Mk-16s. I don't think LERM/LDDM missiles will be as outclassed by Cataphract-As as you think they would be.

Weird Harold wrote:

MuonNeutrino wrote:I wonder if there's an argument for creating a true DD/CL weight DDM. We don't know whether it'd be possible to miniaturize the microfusion reactors enough to jam them into a DD/CL weight missile body, but if so, it might give you the best of both worlds. Such a missile's launchers would be bulkier than the launchers for a Mk-36 LERM or a LDDM, but still far smaller and easier to mount than the launchers for a Mk-16, and the missiles themselves would likewise be bulkier than a LERM or LDDM but much smaller than a Mk-16. The warhead would be the same as a LERM or LDDM (including any potential upgrades), but it'd still have the full true DDM powered range and terminal velocity plus microfusion-powered EW, with salvo sizes and ammunition stowage significantly superior to a Mk-16 design and not that much worse than a LERM or LDDM design.

I don't think it currently is possible to shrink a micro-fusion plant any smaller that the Mk16's. That will change eventually and even fusion-powered CMs and Vipers will be available. LDDMs are an interim design to give dual drive tactical options to legacy ships (and new design smaller ships) without requiring extensive modifications.

As originally conceived, LDDMs were also a second tier, non-GA, missile for LACs in the system defense role.

The main advantage of the LDDM design is that it is doable NOW and in a package roughly compatible with existing launchers. It doesn't require extensive cofferdams or new technology.

LDDMs and CDDMs are not as capable as Mk-16's but they are more capable than the capacitor missiles they are based on. They give ships armed with LERM and ERM missiles an option of dual drive tactical flexibility without the need to drop down a warhead size as the Cataphract design does or extensively modifying existing ships.

Finally, the LDDM concept was initially conceived as an export missile for export LACs by a former OFS sector economy. I'm sure that Manticore would improve on the idea before deploying it in the RMN.

One last thought: RMN warheads are bigger, more powerful on a missile class basis. Especially since the development of the Mod e(1)/Mod-G warheads for the Mk-16s. I don't think LERM/LDDM missiles will be as outclassed by Cataphract-As as you think they would be.

I agree that the Mark 16 is currently as small as you can get a microfusion powered missile. Although, I suppose you might be able to one shorter if you used shorter lasing rods.

However, I don't foresee fusion powered countermissiles or Vipers. Capacitor power works just for anything that's a single drive missile - especially CMs.