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Question regarding Spinal Mounts

I'm noticing in the T20 Hardback book that the different models and makes of Particle Accellerators and Meson Guns don't vary in Damage or Range. Only in Tonnage, cost, EP, TL, and USP.

Why choose one given Meson Gun over another. If a 1000 Ton Meson Gun does the same damage and range regardless of TL, the only drawback I see with the TL 13 model is the extra 400 MCR it will cost. The TL 13 model even uses less power than the TL 14 and 15 models.

By that logic, why mount a heavier gun if the range and damage is the same whether the gun in question is 1000 tons or 5000?

I KNOW I'm missing something here.
Originally posted by Stei'awtliyrl:
...I KNOW I'm missing something here.
I hope you're right but I'm not too sure it's anything you missed but rather something the playtesters or designers missed or failed to explain fully. Again I plead for some official and complete examples of various designs and combat, please :D

Anyway the best I can find and offer is that the USP is a bonus to hit, that's all. You add the USP to your roll when attacking to see if you hit.

Now I can suggest that there perhaps should have been more to the combat section based on the way HG handled it. There the USP is both a 'to hit' factor and a 'damage factor' of sorts. Further though, and significantly so were the extra notes for high USP factors and spinal mounts.

First, if the attacker's weapon USP code is greater than the target's size USP code then all hits that penetrate gain an automatic critical hit for each point of difference, reduced by armor (-1 crit per 2 points of armor) except of course for meson hits (ignore armor).

Second, if the weapon is a spinal mount each hit that penetrates gets an extra damage roll(s) for each point by which the USP exceeds 9, also reduced by armor (-1 extra roll per 1 point of armor) except again for meson hits.

I only mention this because T20 is built so much on CT in general and HG especially for ship design. In fact the above mentioned spinal mount weapons are an exact copy of the stats from HG except for the addition of the damage dice column.
Dont have rule book with me but i think you will find that the USP is the number of dice for damage you role - Mesons do D20's so a usp of 15 is 15*D20 damage and it ignores armour reduction (i dont know if the meson screen works like armour for mesons or not, if not any hit will kill any ship, yes it gives meson AC but does it give AR).
Evening Lionel, that would make some sense of it all, but then the tables need to be errata fixed to reflect that as right now the damage is the same for all USP values.

You're right btw, Meson weapons ignore armor but there is a modifier for hull configuration, some good some not (pg. 157), as an AC bonus. The text above infers that a Meson screen is treated as AR for Meson weapon attacks so it would help degrade the damage if hit. Now how am I going to fit a decent Meson screen in a small blockade runner
My book says that the Meson spinal Mounts do 16d20 accross the board, and the Particle Accellerators do 16d12. Is this in error?

Also, spinal mount weapons enjoy a 5 point bonus to critical hits. (yowch!)
Here's a contentious comment just to get things going ;) .

By going back in time to the High Guard model of ship design, the designers of T20 have thrown out all of the "progress" in ship design that came with TNE and T4.

In the T20 rulebook there are rules for miniaturization of equipment, computers, but no rules for weapons getting smaller with TL.
Ok, the vehicle energy weapons get bigger at lesser TLs than 14, but why does a Type A spinal mount not get smaller?

If such rules were developed officially then many of the TNE and T4 ship designs would still be open to us without massive rules bending.

Perhaps an equipment design book similar to FF&S written for T20 tech would solve the problem ;) . Hmm, meson body pistol... or a briefcase sized fold-out suit of BattleDress...

Am I correct in thinking that GURPs Traveller allows for Spinal Mount size reduction or am I remembering something in error?
I think I'm starting to figure things out. Though the Spinal Mounts inflict the same damage, as far-trader points out, the USP calculated for each weapon is added to the total attack roll.

Looking at the chart, A 1000 ton TL 13 Meson gun has a USP value of 14, giving +14 to hit. The 1000 ton TL 14 model is USP 16, and the TL15 model is USP 18. So, by mounting a 1000 ton TL 15 on your ship, you get a +4 bonus to hit for the same investment in tonnage. Furthermore you save 400MCr over the TL 13 model. However the TL 15 model does use an additional 100 EP.

Compared to the Earliest models at TL 11, the 1000 ton TL 15 Meson Gun enjoys a +7 to +8 attack bonus, weighs 4000-7000 tons less, and costs a ridiculously small amount of money; 400 MCr as opposed to 10,000 or 12,000 MCr.

In addition, larger weapons of the same TL also become more accurate. A 1000 ton TL 15 Meson gun has a USP of 18, the 2000 ton verson has a USP of 22, the 5000 ton verson has a USP of 25, and the 7000 ton verson has a USP of 27.

How this reflects in game terms is that guns with a higher USP hit more often, and do damage more often than guns with a lower USP. From a TL standpoint, it's kind of like the difference in accuracy from a 16 inch gun fired in 1943 as opposed to a 16 inch gun fired in 1991. Both 16 inch shells do roughly the same amount of damage, but by 1991, the weapon system is tons more accurate.

I'm not certain that I agree with the flat damage when the weapon increases in physical size. I can come up with some pseudoscientific babble about mesons, but a Particle Accellerator should do scaled damage based on size. The bigger the gun, the more particles can be accellerated to higher velocities. Thus, more damage. But on the other hand, we are talking 16d20 with X10 critical on a natural 10 or more. That's more than enough boom for my purposes.
I'd like to add another thing I find to be mysterious about spinal mounts in HG2/T20 design.

"Spinal Mount" clearly refers to something that is "the spine of the ship", or at lesat "something that is mounted along the spine of the ship", but I'm inclined to go with the first opinion, as there are rules that state that only one spinal mount is allowed per ship due to "stress and power and other issues".

So far, this is all common knowledge.

Now, on a 500,000 dton battleship, like the nefarious Tigress, equipped with the 7000 dton Type-T Meson Spinal Mount, well, ahem . . .

That's just over 1% of the ship's volume. Honestly, that's not a spinal mount, that's just another weapon tucked away in a corner of the ship . . . even though it has a titanic power requirement in comparison to other systems, far in excess of its size.
At this tiny percentage, I'd say several could be mounted, if not for the power draw.

Oh well, I just have this weird idea that any ship bearing a spinal mount is actually wrapped around it, possibly for three quarters or more of the ship's length.
Wow. When I did a TNE version of the Tigress the spinal meson gun which was a 250,000Mj Spinal Meson Gun had a volume of 652,155 m^3 (46,582.5 dt) massed 447,743 tons consumed 34,722.2225 Mw of power and cost 60440.2 MCr. These HG2/T20 designs are certainly efficient!
Originally posted by Antony:
Wow. When I did a TNE version of the Tigress the spinal meson gun which was a 250,000Mj Spinal Meson Gun had a volume of 652,155 m^3 (46,582.5 dt) massed 447,743 tons consumed 34,722.2225 Mw of power and cost 60440.2 MCr. These HG2/T20 designs are certainly efficient!
That would be FF&S1 . . y/n?

But in any event, that sounds more like it, 10% of the dtons of a 500,000 dton hull.
I think that % based spinal mounts for High Guard ship design would be a good idea.
These are the problems as I see them:
how to determine EP input;
how to figure out weapon code (A-T);
TL effects on size?
Yes, the spinal mount of the Tigress was done with FF&S1.

Spherical configuration dreadnoughts are a bitch. Rapidly running out of surface area. (The Tigress did not have hull room for an EMM masking system)
Given that Gunnery is a skill, therefore a skill based attack roll anything, in T20 over a g is a waste. If you have 10 skill points in gunnery, skill focus gunnery (+2) and heavy metal, (one range band closer) it is virtually impossible to miss with a factor G Spinal mount. You are at +29 to your roll. Before your computer assisted gunnery, your Commander's abilities and your fleet commanders abilities. (Combined easily another +10) You miss on a 1 and the highest AC I have been able to build is 32 and that is a 50T fighter. (Most Capital ships don't get any higher than 20 and the highest published ship is the Tigress (Sup-7 taken as is assuming it actually converts) AC27 (vs PA). Vs a Meson spinal the highest AC possible would be 28 with a capital ship. (Dispersed structure, Meson Screen 9, Agility 6. under 100,000 tons.) Since Gunnery is a skill if you have it as your PMOS then you can take 10 and guarantee a hit and, depending on the GM's interpretation of the Take 10 rule, with a spinal meson which crits on a 10, auto crit the target.

With the spinal meson it crits more often than it hits. (52.5% of the time crits) A crit from a spinal meson does an average of (16x10.5x10) 1680 SI plus 104 (16x6.5) radiation damage. That would take an 8.84 million ton ship to 0 in SI. It absolutely destroys (does twice the SI) of any ship less than 668,000 tons. I don't believe there is a published ship that size. (the Tigress coming in at 500,000)

In T20, capital ship combat is quick dirty and extremely deadly. (Kind of like personal combat was in CT.) He who shoots first invairably wins. And since you can build 4 Cruisers for the price of one Drednaught, with Spinal Mesons there is no real difference in combat power, there is no real reason for Drednaughts in T20. The best overall designs for T20 capital ships are the Atlantic and the CF version of the Azhanti High Lightning. Though a Ship with a bunch of 100T Meson Bays (Crits 30% of the time and two crits kill a Tigress outright) might be more deadly. (The Scout variation on the AHL becomes nasty as well.) A CA mounting 10-20 100T Meson bays is a very nasty customer. Or put one on a Destroyer or a pair on a heavy destroyer (8000 ton range) and you have capital ship killers. Monitors in the 3-5Kton range actually have a serious shot at major damage to an incoming Bat-Ron.