Monday, May 6, 2019

Ultra-Tech Ultra-Quickie: How Much Explosives Are In a Ultra-Tech Warhead?

As any GM can account, sometimes PC's can get a little too clever for their britches and think outside the box.

For example: Let's say after disarming a bomb that was going to take out the presidents personal shuttle one of your players decides they're going to remove its explosive filler so they can repurpose it later.

Great! Smart lil bugger.... Now you just gotta figure out how much boom-boom is in this dang thing. Sure you can just pull a number out of your butt buuuut then you gotta hope you remember why you picked this number later if you have to do this again and hope no of your players are an "expert" on explosives and go, "Actually!"

Well good thing there is a way to figure how much explosives are in the warheads listed in Ultra-Tech!

First you just have to figure out how much a given warhead weighs and if you have read this blog post you should already know how to do this but to make your life easier I'll just give your the formula again.

Warhead weight = Warhead diameter (in mm)3 × 0.000002.

See Warheads R' Us for how I came up with this, my more observant readers might notice that this will give you same results as stating up a small warhead in GURPS Vehicles 3rd ed which in turn is the standard that Transhuman Space used for it's warheads (which in turn was a major influence on the 4th ed version of Ultra-Tech).

Now that you have how much the whole warhead weighs, we can now separate the explosive filler from the casing, fuse and other necessary components. 

To do that just take the warheads weight and multiply if by 0.78 annnnd boom! The product is the weight of the actual boomy part of the thing. Of course in real life this would vary based on what kind of warhead it was, how it was fused and so on this does at lest give you a good rule of thumb that is consistent and lines up with GURPS RAW.


Oh right.... you want to know how I came up with this, silly me. 

Well, if you open up your Basic Set to pg. 415 you'll see there's handy little formula to figure how much damage a given amount of explosives do. You just needed to know the weight and the explosives REF (relative effectiveness factor, or how powerful it is compared to the same amount of TNT).

Now let's look at a 100mm warhead which weighs 2lbs and a TL 9 HE warhead does 6d×5 cr ex.

To give a base line let's look at what 2lbs of TL 9 HE would do (I'll save you the crunch on this one but it's safe to say that TL 9 military explosives in Ultra-Tech are Plastex B/ Octanitrocubane) with a REF of 4).

Using the listed formula 2lbs of HE would do 6d × square Root of (2lbs × 4 × REF(4)) or 6d×5.56, which would normally be rounded to 6 but that would throw off the results. 

Now if we compare how much damage a 100mm warhead does compared to 2lbs of just HE that the warhead does only about 88% of the damage. Now since damage is based on the square root of the weight of the explosives, just convert that 88% to a decimal and square it which gives us a weight modifier of about 0.78. 

So this means that a 2lbs warhead should have 2lbs × 0.78 or 1.56lbs worth of explosives. So if I'm wright, if we plug 1.56lbs into the explosives damage formula we should get 6×5 and look at that, the formula gives us 6d×4.99 dice worth of damage. Bam! 

Oh, and another use for this knowledge is now you can swap out the plastex B and try out different types of explosives. For example, if we decided that we wanted that 100mm warhead filled with Nanoscale Thermite (Ultra-Tech, Too Pyramid 3/51 Tech and Toys III) we now knows that it can hold 1.6lbs worth which will burn for eight seconds and cost $320. 

I know this wasn't too big of a post, especially with how long I've been out of the game but rest assure I do have some more post in the works, two that give you more warheads to play should be done soon, with as well doing some major research into Robotech: The Next Generation/The Sentinels mecha and weapons so I should have more Ultra-Tech fun for you guys soonish. 


  1. Hello there. I'm curious, do you know about such development as reactive materials?
    They already try to implement it in rifle/shotgun caliber rounds.

    1. While your link lead me to a 404 page I think I know what you're talking about.

      They're rounds loaded with a fine grain powder that react like in a flour or dust explosion (or a thermobaric warhead).

      While I'm iffy on them really doing much more damage then a hollow point, if they do really work as advertised then I would have them bump up the base Pi damage the round does by 2 steps (i.e. from pi to pi++). If the round is already pi+ or pi++ then it's treated as an automatic vitals hit for 3× the wounding effect.

    2. Thanks for reply. )
      Well, both links worls from my side, so must be some glitch. But, yes, you got it. They got surprisingly low amount of coverage (and so far only breaching shotgun round was demonstrated, see at ) but I was able to collect some data from patents and scientific journals. Quote from one abstract:" High-energy metal–fluoropolymer RM with moderate
      strength and density (2–3 g/cm3) are implemented in missile warheads, armor-piercing incendiary bullets, and shaped charges. So-called HDRM became an independent branch of RM investigations. High density (7–8 g/cm3)
      and strength (140–600 MPa) make them suitable for structural metal replacement and upgrade different munitions without changing the weight and size characteristics. It is possible to use HDRM for producing shell casings, warheads, and reactive fragments. Structural RM (or RMS) have similar properties, but their density and strength are provided by the metal frame. Tungsten wire reinforced composites achieved density and strength close to
      that of the structural steels. The experiments confirmed the possibility of RMS use in penetration bombs at impact velocities of 300–760 m/s. Explosive compositions with tungsten additives, DIME, increase the density of equipment and may be used to reduce side effects of precision weapons without damage efficiency reduction.
      In RMBX, tungsten is replaced by pyrophoric heavy metals (for example, Ta). The energy release of RMBX (∼ 30 kJ/cm3) provides the blast perfomance higher than the conventional thermobaric explosives".
      I would say, they would fit straigth into TL9 APHEX territory. And I suspect that they, much like Mk211 .50 cal would need a hard hit to initiate reaction.

      And it seems that shells/warheads with high-dnsity structural RM casing would yield a bit more explosive power.

    3. Yeah, this is pretty much what TL 9 thermoberic warheads use.

      As for reactive fragments are covered in Ultra-Tech Too in Pyramid 3/51 Tech and Toys III.

      And if i recall Keith (tzeentch on the forums, he's who wrote Ultra-Tech To) had some unfinished rules on HD-explosive casing....

      Here, after about 40min of looking heh:

      Solid Explosive Warheads (TL9)
      Only about half the mass of an average warhead consists of explosive material, the rest is composed of fusing, casing, stabilizing filler, and shock proofing reinforcement. Ultra-Tech warheads and explosive projectiles can be constructed of solid explosives milled to shape and coated with a thin protective shell, dispensing with these supporting materials. Fusing and associated components (actuators and metal plates in SEFOP warheads, for example) are embedded within the explosive mass. This design option presents significant safety and handling issues, and is highly unlikely to be used for mass-use or general-purpose munitions, but is an option for special-purpose applications.

      Conventional warheads with this option multiply their explosion damage (not follow-up attacks) by ¥1.5. For example, a 40mm TL9 HEC warhead (Ultra-Tech, p. 154) with the solid explosive warhead option does 12d cr ex. Multiply the cost of the warhead by ¥5.

    4. That sounds saneand not out of balance, thanks. )

      I was also thinking about Ultra-Tech rifle grenades. I ended up with coclusion that most sane would be "baseline" TL9 "64mm" hand grenade, that can be fired from slugthrower muzzle in a pinch, most probably with "bullet-thru" design.
      Then when Raytheon Pike comes out, I start to think about its bigger rifle-launched variant... sile TL9 Hunter missile with lesser range but without backblast and with no need of dedicated launcher maybe?

  2. Ultra-Tech rifle grenades eh? Might have to give that idea a look. Probably while have to look into Traveler style RAM grenades while I'm at it.

    Now for the idea of a rifle launched missile? Well if it's the same size of a rifle grenade then you just got a fancy gyroc launch system heh. Speaking of which, I might just have a future post on that topic in the works.

    1. Well, despite rifle grenades are mostly eclipsed by UBGLs, one still can find perfectly good rationale for them: they caryy a bigger warhead and need no attachments for rifle.

      Heh, unfortunately gyrojet development seems completely stalled, so gyrocs are unlikely to happens in our TL9. ))

  3. Actually, speaking of warheads. I believe that at some point fragmentation damage should get armor divisor.
    Basically, 25- and 40mm HE grenades should be able to inflict damage on personnel. Then we have TL9 reflex suit which provide DR12 against cutting damage. And it will protect from 25mm 1d+1 almost completely. Now, with 1d+1 (2)... Think about "superfine fragments", like superfine blades.

    1. I can see that as an option and while I don't remember where I put my notes I did at one point stat up a hyper dense for TL 11^+ HE rounds.

      I also wonder what a TL 9 continuous rod warhead would do to TL 9 infantry. Hmmmmm.....

    2. I believe that I saw something like this in "Chainlink&Concrete"...
      And here it is:
      "You could have a Mk II with Skill 13 and Rcl 4 [2d], an M26 with Skill 14 and Rcl 3 [2d], and some futuristic grenade packed with an explosive unknown to us yet with Skill 15 and Rcl 2 [3d+1(2)] tungsten carbide coated depleted uranium fragmentation payload for MAXIMUM WRECKED".
      Nice to see.

      And one more little thing about Ultra-Tech warheads. Default TL8 HEAT charge liner is made of copper, what is baseline metal for TL9 one? Tantalum?

    3. Well the two major factors for a liner material is it needs to both have high density as well as high ductility, that is it can be pulled into a fine wire. Things like melting point and hardness also have an effect.

      The reason for this is a shaped charges penetration can be molded as a an impactor of Newtonian approximation. That is a projectile will penetrate to a depth equal to it's length times the square root of the projectiles density divided by the density of the marital impacted.

      Or P = L × square root(pj/pt)

      Where P is penetration depth, L is length, pj is density of the projectile, and pt is density of the target.

      So with this it's very apparent why density is important. It's the the L part were a materials ductility is important. This is do to the "fist to finger" rule of thumb. It's the "finger" that acts as the L part of the formula and the greater to materials ductility the longer that "finger" can get before it breaks apart.

      That's why copper is used for both shaped charges and wire.

      Currently advanced HEAT rounds use molybdenum as their liner and with a density 16% greater and 60% greater ductility then copper this is probably going to be the stander for at lest early TL 9 ones. A pseudo alloy of copper and bulk amorphous tungsten might work for later TL 9.

  4. Yep, I erroneously mentioned tantalum, while concept of enhanced 40mm HEDP round specifically mention molybdenum.
    So, as a rule of thumb, light TL9 shaped charge would have penetration about 5 diameters?

  5. Closer to ~8, even modern day warheads can manage about 6.5-7 diameters in practical situations (double in controlled tests). In fact if you multiply 127mm by 6.5 you get the performance that High-Tech specifies for the FGM-148 javelin anti-tank missile.

    For example: A 40mm TL 9 shaped charge does 6×4(10). The average penetration of RHA equivalent for this is 6 × 4 × 3.5 × 10 or 840 points of basic damage. Divide that by ~2.76 to get penetration in mm or 304.8mm. Take that product and divide by 40 and you get 7.62.

    In Ultra-Tech at lest, shaped charge performance seems to go up by the a factor of about 1.15× each TL (basically it follows the cube root of the size/speed/range table progression of 1.5, 2, 3, 5, 7, 10 for each increase of TL). It should be noted that the TL 9 shaped charge in Ultra-Tech is actually what we would now consider a HEDP round, the TL 10 version is the same thing, just given a different name just tome it easier to differentiate the TL 9 and 10 versions).

  6. That's when rifle grenades come in mind.) "Hellhound" 40mm grenade, which, I think, can stand as TL8 HEDP, loaded with 88g of Comp A5, had advertised penetration of 90mm of mild steel, probably less with RHA. Belgian Mecar M200 HEDP rifle grenade is loaded with 38g of Comp A, but it's fin-stabilized (spinning not contribute to reducing damage) and have better standoff distance due to longer nose. So, with smaller caliber and lesser charge it penetrate 80mm RHA.

    At TL9 they really can be a potent thing. Not a dedicated anti-tank weapon of course, but nasty surprise just in case.

  7. The thing with shaped charges is you need a right balance of explosives relative to the mass, diameter and type of liner you are using. To a point you can maybe get a little extra out using a bit more explosives but it would quickly give diminishing returns and if you add to much you risk shattering the liner rather then putting under hydrodynamic pressure.

    Also instead of a nose I'd just use a laser range finder for a TL 9+ weapon heh.

    1. Actually yes, I was thinking that laser-based fuze would probably reduce size and weight of a warhead.

      Yes, looks like even 64mm warhead-based TL9 rifle grenade would get about 530mm of penetration, whic is nice for about 1lb weight.