Some TL8-9 weapon ideas & stats

[Joseph Paul]

Originally Posted by Anthony

GURPS handling of HE has plenty of issues, but realistically it's pretty cruddy at destroying compact objects like weapons and equipment because the effect scales strongly with the size of the object being hit (and conversely, it's really good at destroying buildings).

It doesn't need to utterly destroy a weapon to make it useless. Take some HP and roll on a table to find a subsystem that is now gakked. Optics, Commo, ready ammo, mobility of suits or even environmental controls could be messed up. Barrels misaligned, receiver jammed, stock broken, trigger jammed. Computer off line from the shock.

We don't check on those things.

I need to play around with the knockback rules and decide if the exoskeleton and powered armor suits' strengths apply.


Some of the real world testing of artillery effectiveness appeared in a article titled "Who says dumb artillery rounds can't kill armor?"

https://sill-www.army.mil/firesbulle...LL_EDITION.pdf

They are using larger 155mm rounds but it is all HE not SCW submunitions. A number of the pics show what near misses can do with 'near' being under 30 meters.

There is a STANAG standard for what threat level a vehicle is rated for and some of that involves testing for fragment damage from shells. There is a standard for the simulator of those fragments - a 20mm round with a special blunted projectile doing 960 m/s from 25 meters 24,791J. So there is some numbers to compare fragmentation damage with.

[Rupert]

The real problem with the fragmentation rules is not the damage fragments do. It's that the effective reach of warheads doesn't change with size - they all throw the same number of fragments, effectively.

As the rules for fragments treat them as being an automatic weapon with skill-15 and Rcl 3, every doubling of the number of fragments should give a +1 to hit. As the damage of KE attack (bullets, etc.) scales roughly with the square root of energy, and the total energy that goes into the fragments should, all else being equal, scale with the mass of the shell, it would seem that the number of fragments scales with the cube root of mass, and thus linearly with shell diameter. So, every doubling of shell diameter is +1 to hit for fragments.

A case can also be made for each doubling of fragment number (and thus density doubling the range at which a target would get hit, in which case the bonus to hit should follow the range/speed table (this implies that rapid fire should too, which some people have floated in the past).

The next question is what should the baseline shell diameter be, and how should rounding be done? This is really asking where the break-points for smallish explosive rounds should land. I'd be inclined to give 30mm +1, making 15mm +0 as there's not a lot that going to be smaller than that. It also puts 20-25mm grenades and cannon in the same group and 30mm as clearly larger, which is how it tends to play out with real weapons. The next step is 60mm+ (+2), which includes just about all mortars, UT hand grenades and man-portable missiles, light artillery, and so on. Then we've got 120mm+ (+3 - at this point if you'd have been hit anyway you get hit an extra time), 240mm+ (+4), and so on - serious artillery, large rockets and missiles, bombs etc.

[Nightrider_88]

I'm not if such a warhead would work, but many layers of pre-made fragments surel y would be... more fragments, that in one outer case. Invention claims, that they should fly faster due to more efficent use of expanding gases, but here I became unsure.
http://www.freepatent.ru/patents/2476813

[Rupert]

Originally Posted by Nightrider_88

I'm not if such a warhead would work, but many layers of pre-made fragments surel y would be... more fragments, that in one outer case.

Pre-forming the casing, and/or putting notched wire or pre-formed fragments (ball bearings, etc.) in shells is a common practice. It gets you more fragments, though each one thus has less energy. Following the assumptions about energy -> damage, and number of fragments -> hit chances, halving fragment damage should get you +2 to hit.

It'd be quite reasonable to decide your 120mm mortar shells don't need to do [6d] fragment damage, and design them to instead do [3d] with +2 to hit (and using my suggested rules above, an additional +2 for being 120mm+ in diameter), giving them a lot more reach on average.

[Nightrider_88]

Also, here.
https://ndiastorage.blob.core.usgovc...069Shipley.pdf
Here we speaking about our corrent 40mm grenades. While I still think that weigth and material of fragments are more on damage side, warhead shape and overall number of fragments really shoukd contribute to hit probability.

[Jack Sawyer]

Originally Posted by Nightrider_88

And Poland.
So, I really thought, that 64mm warhead-based rifle grenade would be ince addition to Ultra-Tech.

It'll depend on role/purpose. Every weapon or piece of gear you give a soldier has tradeoffs, and weight is an omnipresent concern. And if you ask current/former soldiers about militaries reducing weight, you'll often see them laugh at the idea. Mainly because even if they do, someone else will find more gear to dump on them and negate that advantage.

I've heard that X-product drums are good enough, but yes, I know that coffin mags still not worked out, so I mention them mostly as later possibility.

Reliability is one issue, but weight/bulk is another. Most drum mags I've seen are pretty darn big (and expensive) and I'm not sure they'd work for the average soldier (weight remember). IIRC they're being tested for automatic rifleman/machine gunners but that's it. If you go with a poly CT ammo, you might have a belted 'drum' because from what I've heard CT works BETTER with belt fed rather than mag fed.

Yards) But increased range is not a demand, I think there was suggeston that improved ballistics would affect it.

Well lots will affect 'effective' range, including recoil and the metrics you gauge it by (they aren't fixed.) I brought it up more as 1.) a possible over-engineering issue (generally not desirable from a cost/reliability standpoint) and 2.) tradeoffs (because again there probably will be some to properly exploit extended range.) 'Do it all' Compromises from what I've seen tend not to work out for most firearms, even though (for example) the US Army always tries to do it anyhow (SPIW, ACR, and the current NGSW program)

So far only RM ammo demonstrated were that one,
https://www.youtube.com/watch?v=b68C7-8u5O0
And I still waiting for Lehigh Defense promotional video (they promised to include this one in it: .338)

The first one is basically a shotgun round, so we're veering onto 'grenade launcher' territory and it should have enough mass/volume to make it meaningful. Not sure a .338 round would though and LeHigh has a reputation for making some.. interesting ammo choices. Not as absurd as the G2 Research RIP, but I've seen mixed reviews about them.

Volume constraints for a given round are often a big problem for add-on effects, which is why it seems 7.62 incndiary/explosive rounds are rare and specializd (yes I know about things like B-Patrone and there is at least one Russian API. I also know there's been alot of argument about them on various gun/miltech forums because of the volume issue, hence the rarity.)

There was whole point of dual layer - first one should penetrate armor, as it does, that reactive jet comes via penetrted hole and... do the damage. I believe there is whole paper:
https://www.mdpi.com/1996-1944/12/17/2768/pdf
To quote:"Experimental results showed that, compared with the single reactive liner shaped charge jet, a deeper penetration depth was produced by the reactive material-copper jet, whereas the penetration performance and reactive material mass entering the penetrated target strongly depended on the reactive liner thickness and standoff".

It sounds more like they're a laminate and the reactive layer is delayed long enough so that the copper jet can form and penetrate deeper - the reactive element will disrupt the jet as the article notes:

However, although this class of reactive material jet can form a larger hole-diameter on the target, and its deflagration reaction inside of the target will produce enhanced structural damage, its penetration depth is always lower, which makes it difficult for a reactive liner shaped charge to efficiently penetrate a thicker steel target [27,28]. This is mainly because the chemical reaction of the reactive materials occurs before the jet perforates the thick steel casing of targets, resulting in the reactive materials not entering the target and not producing enhanced behind-armor effects.

Better penetration than past efforts, without sacrificing BHE. Thing is it sounds very timing dependent and the description is rather complex (which they admit) which again suggest there could be reliability concerns (Shaped charges are already finicky as far as jet formation goes, remember.)

That said the concept itself (regardless of the specific approach) seems sound. Patents for a dual layer SC go back to the 60s and I found one other theoretical approach. So if your definition of realism includes 'its possible' this is entirely viable (with handwaving I suspect) even if currently known methods may have issues. On the other hand this might be a concept that would work better with something like MAHEM too given timing/reliability issues.

Originally Posted by DanHoward

Looks like the 6.8mm case-telescoped round is a done deal. It also looks like the Army has accepted True Velocity's composite casing design too. Won't know for certain until Northrop builds the new manufacturing plant at Lake City.

General Dynamics even proposed a bullpup design to allow for a longer barrel and more MV to meet requirements. And TV's ammo has gone for a very non-traditional shape even as it allows for extraction like traditional ammo (unlike Textron's entry.)

Originally Posted by Nightrider_88

But how many rounds do you need to reliably disable even a lighter amored vehicle? Then, in anti-personnel role: we have TL9 reflex suit which provide DR12 against cutting damage. Will it protect from 25mm 1d+1?
I'd say, that as ammo for anti-materiel "payload" rifle 25mm would totally justify itself. As squad-level multipurpose support asset... well, too borderline.

I'm not sure you would bother trying to use 25mm grenades to disable an armored vehicle unless it was an emergency. It's like expecting your AR to defeat armored vehicles - it's not necessarily what it was designed for. Hell I'm not even sure 40mm would do it without some handwaving. Too small a round. If you want to disable vehicles you're probably going for an RPG or Recoilless rifle or rifle grenades. And this is especially important since you proposed enhanced Behind Armor effect. A bigger round gives more volume to exploit that, wheras a smaller one requires more compromises.

Remember not to forget about tradeoffs in equipment choices. You probably can't have everything (at least not without some hefty handwaving.)

Originally Posted by Nightrider_88

Then, anybody remember DIME? Tungsten "dust" instead of fragments.
https://en.wikipedia.org/wiki/Dense_...etal_Explosive

DIME is meant for limited collateral damage without sacrificing lethality within that reducd range, so we're talking 'tradeoffs' again. And I think there's been some controversy over it (not surprising since tungsten is a heavy metal technically so I believe there are toxicity issues like you got with APFSDS ammo.)

Originally Posted by Anthony

At the same mass and velocity, tungsten will be better than steel or lead, but I wouldn't think it would be worth the extra cost. The root problem is that shrapnel just isn't very powerful and, not being stabilized, is forced into configurations that have poor performance against armor (it's sort of like using tungsten shot in a shotgun; 1d(2) still won't penetrate level IIa armor).

Here is an RE Factor chart for different explosive compounds along with density and velocity. As you can see eve something like CL-20 or HMX isn't much slower than ONC so it seems you're correct. I've seen Octaazacubane which clames 23 MJ/kg and a 15 km/s detonation velocity, but its entirely hypothetical (so on the same level as metastable hydrogen, SBER or an isomer bomb.)

Originally Posted by Fred Brackin

I've heard some talk of exotic metal-based explosives. If they are even denser you could hit the UT numbers as shell fillers if not REF/unit of weight.

There's lots of theoretical ideas floating about if you're willing to look, like Structural Bond Energy Release which seems like what those crystal power sources the Posleen novels had, but its right up there with metallic hydrogen. I'm sure I have seen others, but I'd have to dig.

[Anthony]

Originally Posted by Jack Sawyer

DIME is meant for limited collateral damage without sacrificing lethality within that reducd range, so we're talking 'tradeoffs' again. And I think there's been some controversy over it (not surprising since tungsten is a heavy metal technically so I believe there are toxicity issues like you got with APFSDS ammo.)

It was initially assumed safer because of low solubility, but that appears not entirely true.

[Nightrider_88]

Originally Posted by Jack Sawyer

The first one is basically a shotgun round, so we're veering onto 'grenade launcher' territory and it should have enough mass/volume to make it meaningful.

Or TL9 18,5mm HE round. )

Not sure a .338 round would though and LeHigh has a reputation for making some.. interesting ammo choices.

So for one can only assume, that if even lower-density RM are... denser than conventional explosives, han it's possible to stuff about 1 gram into normal rifle round (some patents like RU2616034 suggesting even hard outer shell with RM-filling like PELE rounds).
Also, tests were made with RM slughs with about 6-7grams of weight.
http://book.sarov.ru/wp-content/uplo...dej-2017-1.pdf

So I think that .338 would work, especially if it can pass as strictly anti-materiel round, not violating Saint Petersburg Declaration. )

That said the concept itself (regardless of the specific approach) seems sound. Patents for a dual layer SC go back to the 60s and I found one other theoretical approach. So if your definition of realism includes 'its possible' this is entirely viable (with handwaving I suspect) even if currently known methods may have issues.

That's nice. ) Do you hink, that tripling penetrating damage is good enough approximaion?

DIME is meant for limited collateral damage without sacrificing lethality within that reducd range

Question is, would be it the same dice of damage with reduced range?

[Varyon]

Originally Posted by Anthony

The evidence for metallic hydrogen actually being metastable at moderate pressure is... nonexistent.

To be fair, REF 25 (if accurate) gives us room to play around some. If HEDM requires 4x its weight in container (or whatever) to keep it at metastable pressure, that still gives you something like REF 5 (if 10g of HEDM requires 40g of container but is equivalent to 250g of TNT, that means 50g of HEDM+container is equivalent to 250g of TNT, for REF 5). Spaceships seems to assume the "scaffolding" necessary to keep HEDM stable is negligible in weight (or is jettisoned as the HEDM is used up).

[AlexanderHowl]

The performance in Spaceships is pretty close to the 216 MJ/kg of metallic hydrogen (I think I calculated it at 75%-80%), so the scaffolding becomes part of the reaction mass (the temperature would vaporize anything used as scaffolding).