Tuesday, May 31, 2022

Ultra-Tech Firepower: Ramblings on Ultra-Tech Missile and How to Make them I Guess

Hey everyone! 

Guess what?!

It's that time once again! Time for your favorite crunchmeister to beat upon my favorite dead ultra-horse! This time trying my hardest to wack out the wonkieness behind how Ultra-Tech designed its missiles!



One subject I've been meaning to dive into was expanding options on Ultra-Tech missiles. The book its self only offers a scant 2 proper missiles, only one size of gyroc, and a weird homing bullet option that is honestly kinda janky (I mean, there's not a lot of guns in the book. Would it of hurt them to add a single line to each entry that listed it's stats if turned into homing bullets with a increase by X at TL 9, by Y at TL10 and so on). That's not a lot of rocket flavored meat to sink your collateral damage loving fangs into.

So what held me up?

Well. Do you really even need to ask?

That patented flavor of Ultra-Tech kludge rears it's oddly edited head once more.

You know the drill by now. For the most part I try to keep my numbers in line with RAW and so on and so forth but then published stats start to contradict themselves and I have to wack my head against the proverbial wall (and given what I do for a living... I must, like, feed off of an unhealthy mix of pure stress and forcing my brain to unravel logic defying puzzles... I.. I think I need help >.>) until enough neurons are jarred into the right quantum state that the answer finally dawns on me.

And when it comes to the published missiles, not one of them seemed to follow the same rules.

Or so I thought. I mean... it's not like this is that much of a mystery... no much point of posting this blog post if I didn't... I mean I could of written this to trick you into thinking I figure this out and then at the last second be like, "Oh man, fooled you! You thought I had something cool to say but I just wasted your time instead. You're such a fart head for falling for it.", buuuuuuut... I'm to lazy for that and I like having people who... keep reading this blog...

Ah-hem.... sorry... I might be losing my mind a bit here.... carrying on....

The first issue was figuring out if there was in fact any logic behind the numbers and not just an ass pull. My first thought was that maybe David used an early version of the GURPS Spaceships system to design them and came up with nothing. Then I gave building them as vehicles a try. Not even close. Then it dawned on me. Since a lot of Ultra-Tech is based on Transhuman Space maybe, just maybe, he used the Launcher, Torpedo, and Missile Design system found on GURPS Vehicles pg. 113 since he used it to stat the OG 15mm and 30mm gyrocs found in that setting (I'll cover how he did that in a bit).
Going with that idea I took the TL 9 version of the 64mm missile from Ultra-Tech pg. 146. It weighs 2lbs, has a 0.5lb warhead (see this post on how this was figured), has a speed of 500 yards/seconds and a max range of 4,000 yards (meaning an 8 second endurance). Running this though the Launcher, Torpedo, and Missile Design system we have a motor weight of 1.5lbs which gives us an E of 0.15, its speed gives a V of 20.25, and under 3rd edition a TL 9 rocket would have an T of 240 and this gives us an endurance of (1.5/2) × 0.15 × (240/20.25) or 1.3 seconds which gives a range of.... 650 yards. Well nuts. So much for that I thought but then something just clicked in my head. I thought, what if David changed the numbers for the Tech Level variable and my mind just clicked an a nice round number of 1,500. It even works within the normal GURPS logarithmic progression! Like honestly, that was it, it popped into my head like poof! So I plugged the numbers in again but this time with a T of 1,500 and got am 8.3 which rounds down to a nice and neat 8 seconds which in turn gives us a range of 4,000 yards.

 I had figured it out!

 Oh, if only it was that easy....

Next I had to try it out on the 100mm version. Now I always found this missile to be oddly heavy for it's performance compared what a dinky lil' 2lbs missile was able to do. At that weight the 64mm missile has insanely good performance (an issue that I will also be covering later) but while the 100mm missile has better speed and range, it's performance relative to it's weight felt off. And in fact when I tried out my modification of the design system on this one.... it ended up giving the missile over 4 times the range. It would take a T of 350 to have the stats line up at 25lbs and that's kinda bad. While it's better then the figure given in Vehicles, there are already missile with similar performance in the real world. So I figured I was wrong. Maybe their stats were completely arbitrary and the fact thing work that well for the 64mm missile was just a fluke. I was about the hand in the towel and give up when something odd caught my eye. In the info blurb explaining the 100mm Tactical Missile Launcher listed the cost of the missile as being $400 dollars. Wait... that's only 4 times the cost of it's little brother... Even it's blackblast was only twice as much (or the square root of 4). This would imply a 8lbs missile... which is what a scaled up version of the 64mm one would weigh. I then flashed back to when I was figuring out the weight of the warheads in Ultra-Tech I remember that the Striker Missile (Ultra-Tech pg. 168), the genius version of the 100mm missile, only had a ST/HP of 6 which is what a 8lbs weapon would have. Hold up.... was the 25lbs listed a typo? Was it really supposed to be only 8lbs? I had to give it a shot! I plugged in the numbers for an 8lb version of the missile, a motor weight of 6lbs, a V of 144 and a T of 1,500 which gives us an endurance of 4.7 seconds which would be rounded off to 5 seconds which gives us the listed range of 10,000 yards. Well, would you look at that. Looks like I cracked the code after all!

So with the two missile out of the way it was time to see if this same logic would work on the 15mm gyroc rounds annnd spoiler alert.... while it does kinda work... I really do think the numbers used here were in fact just an ass pull to  better line up with the real world gyrojet (see High-Tech pg. 99) rather then the hypersonic but short range micro-missile from Transhuman Space that inspired it.

Of course that being said, you're probably wondering about how I was able to check if the 15mm gyroc round fell in line with my assumption. After all we don't have a speed to work with. Well lets go over how it was stated in Transhuman Space, which was using the very same  Launcher, Torpedo, and Missile Design system. To better help authors write for the setting, Transhuman Space had a Technical Appendix that explained the assumptions of the setting and how they interact with GURPS Vehicles. In that they were treated as being TL 9 and had a speed of 650 which gave a duration of 0.78 which translated in a range of 507 yards which was rounded down to a neater 500 yards. So what happens if you beef them up to 4th edition standards with that T of 1,500? Well...it doesn't work, you get a range of almost 3,200 yards. But, here's the thing. You don't want the gyroc round to char the flesh from your hand or melt your gun so you're gonna want to use or slower burning, lower pressure propellant. However since the it's going to take longer to reach top speed you're going to lose some range. So on a whim I tried a T of only 1,000 to represent a lower pressure propellant and got a range of 1,950. Pretty close buuuut I think this one was more dumb luck then anything. But it does at lest gives us a way of stating up more variants that at lest will sort of fit. That's a win when it comes to tackling the crazed beast that is Ultra-Tech.

Ok, so here we have it! If you want to stat up new missiles for your Ultra-Tech campaign, make the following adjustments to the Launcher, Torpedo, and Missile Design system from GURPS Vehicles (pg. 113). 

Use the rules found in this post. Note that I will have additional options in a up coming post.

Ignore this section and use the options on Ultra-Tech pg. 146. Again, more options will be forth coming.

Unless you want to add some kind of cargo to the missile this will just be the weight of the warhead.

Ignore the part on space missiles, those are not covered here. Motor base cost is based on the total weight of the missile × $50 for an unguided rocket. For guided missiles modify base cost by the cost modifiers listed on Ultra-Tech pg. 146.

Ignore the sections on Malf. and Guid.
Gryrocs still use 3rd edition rules this to figure damage.
Missiles use the 4th edition bullet damage formula. Use √(Kinetic Energy in Joules1.04/(π × (warhead diameter/2000)2)0.314)/46.8741 to figure dice of damage. It should be noted that damage figuring using this formula won't line up 100% but lines up will current GURPS stats and is the formula derived by Douglass Cole (meaning it's the best we got until the official stats are released).

Ignore Explosive and Special damage.

T is 1,500 at TL 9, 2,000 at TL 10, 3,000 at TL 11+ for missiles. 1,000 at TL 9, 1,500 at TL 10, 2,000 at TL 11+ for gyrocs.

Ignore Minimum Range

Is 3 for missiles, depends on the launcher for gyrocs.

For Pistol or Under Barrel Launchers Acc is 1.
For Pistol Launchers under 0.5lbs Acc is 0.
For Rifle Launchers Acc is 2.

Launcher Design
For Missiles
Weight:  Change R to just 1 if reloadable, 0.5 if disposable, Ignore T. Change M to 1+ (0.15 × number or tubes).
Cost: Launcher Weight × $1000. Disposable launchers should cost less but there is not RAW support for this in Ultra-Tech. GURPS Vehicles having disposable launchers cost 1/10th as much does make sense though.

For Gyrocs
Weight: Gw × Rn × Cm.

Gw is the weight of the gyroc round.
Rn is the number of rounds it an hold.
Cm is 2 for under barrel launchers, 2.5 for pistol sized launchers, 4 for rifle sized ones.

Cost: Iiiiiiisssss a good question. There seems to be no rhyme or reason for their costs. So the following formula is completely made up. $75× Launcher Weight × 1 if semiautomatic or 2 if full auto.

Ignore everything past this point except for Rate of Fire.

Rate of Fire
1 per tube for missiles, 3 if semiautomatic or up to 10 if fully automatic for gyroc launchers.  

Legal Class
Is 1 for all missiles

3 for pistol gyroc launchers
2 for rifle and under barrel gyroc launchers
1 for full auto gyroc launchers.

For missiles this seems to be simply based on weight, ignoring speed or other facts (yeah, I know... but that's RAW) burning damage is √(Missile Weight) × 1.4.

Gyrocs do not have backblast but do to their slow acceleration they take time to reach their full damage. See Ultra-Tech pg. 144 for these ranges.

ST, Bulk, and Rcl
Unfortunately, with the exception of Rcl which is 1 for both missiles and gyrocs, the official stats for these haven't been show or hinted at on the forums. As a stop gap since Rcl is 1 just use the formula from the Blaster and Laser Design System from Pyramid # 3/37. At the small arm scale it should give you reasonable results, just cross reference what you get with the stats of similar weapons in High-Tech to see if they fit.

Well here's how to stat missiles and gyrocs as close to RAW as I can get. But... while as I said before I try to get stats as close to RAW.... I have some issues with RAW in this case. You know how I was hinting at having an issue with the 64mm missile earlier? Well, even at TL 9 it's performance is crazy. It's too good. It's only worse at TL 10. To give you an example let's assume a TL 9 version. A base round costs only $110, $100 for the missile and just $10 for the base KE warhead. Let's make it a Viper round with a Shape-Charge warhead. This bumps the cost to up to to only $420. This is for a 2 lbs weapon that can reach mach 1.3, hit a target over 2 miles away with an effective skill of 16 (13 plus an acc of 3), and takes a DR of almost 1,500 to stop. Throw it in a disposable launcher and you have an Ultra-Tech  version of the NLAW that only weight 4 lbs loaded and costs (assuming the 1/10th modifier for disposable launchers) a total of $620. This is cheap and light enough to pass it out like candy and ripple fire it over come tanks APS's and make pink misting a battlesuit trooper so easier that suiting up is almost suicide! While even if this might work for your game setting I think you can still see that this is over kill in most games. And let's be honest.... while there have been massive advances in miniaturizing missiles with example such as the Refael's Mini-Spike and Raytheon's Pike, these systems make compromises to be so small and TL 9 version are going to be better of course but the performance in Ultra-Tech is ludicrous.

I also think there are issues with other stats such as backblast only being effected by missiles weight and not the thrust needed to move it. So moving forwards I am going to use slightly different assumptions for my missiles I stat for my blog. After thinking long and hard I found a T of 750 at TL 9 (1,000 at TL 10, and 1,500 at TL 11+. That level of performance makes more sense at such an advanced Tech Level)  gives a good balance of realistic increased performance and playablity. I will also be using more sensible figures for things like backblast and other stats. I'm also working on a more detailed guidance rules but that's a post in and of it's self since it's going to totally rework 4th editions rules for guided and homing weapons to make them more realistic while still working within the basic frame work.

If you want to use my house rules, follow the rules I laid out already but change T to match the figures listed above (Gyrocs use a T of 500 at TL 9, 750 at TL 10, 1,000 at TL 11+) and change the backblast damage calculation to:  
∛((Kinetic Energy of the round in kilojoules*(The T value used/750))*0.5. If building a gyroc multiply this by 0.03. Realistically you don't want them to have significant backblast but if you make the engine powerful enough it's still going to do damage at some point.

Divide the cost of disposable launchers by 10.

Gee's of Thrust: If you want to use the missile in space (assume any TL 9 + Missile that has a speed over 400 yrds/sec is space capable), here's simple system that gives you good enough results. Assume it has an acceleration in Gs of (Missile Velocity/120)*(The T value for the given TL/750). The missile will accelerate this much for as many rounds as it has endurance.

Distance to Reach Peak Acceleration: Both regular missiles and gyrocs should take some time to reach their top speed, it's just that gyrocs takes longer so minimize backblast. To figure a missile 1/3rd damage range divide missile velocity  by 975 and then multiply it by (The T value for the given TL/750). 1/2 damage range is 5 times 1/3rd damage range. Divide both ranges by three for gyrocs.

Kick Motor Option: These motors help manage backblast by by using a soft launch system to punt the missile a given distance before falling off and letting the main motor take over.

First stat your missile as normal.

Next build another missile with the weight of the original missile as payload with these following changes: T is 20 at TL 9, 30 at TL 10, and 50 at TL 11+, motor weight shouldn't be more then a quarter of the weight of the missile it's launching, Velocity shouldn't be higher then 90 yards per second.

Backblast is multiplied by 0.25 and is crush instead of burning and follows the counter mass rules from the box on High-Tech pg. 147.

Cost is motor weight times $5.  

Alrighty guys, I hope you find these rules useful. You now have two options to play around with so I hope you have fun reaching out and touching some baddies with your new toys.


  1. At last, just what I needed. Excellent!

  2. Honestly, I always wasn't sure, what kind of niche 64mm missiles should fill. UT sounds like they should be used in all guises, from cheapo disposable infantry tools up to gunship armament. I don't think that they good for both sides of spectrum, especially if default 64mm warhead equals to common hand grenade.

    1. Warhead power isn't everything. The NLAW has kinda crappy penetration for it's caliber (though it's warhead seems to be some kinda EFP/HEAT hybrid). What makes it effective is it's only 1lbs heavier then a hand grenade, can take warhead options that a grenade can't, and can hit a target two miles away in only 8 secs and if given a guidance option do so with scary accuracy. And the biggest thing, they're dirt cheap. Now one 64mm round might not be a threat but a squad or even multiple squads ripple firing them can clear out a battle field real fast (this is a major force multiplier).

    2. I always said that even cheaper and lighter 64mm rifle grenade would add even more disbalance))

    3. Not as much as the missile form. Rifle grenades have short range and are dumb fired. Also harder to get a top attack with then meaning they'll more likely hit an area with more armor then the top. It shouldn't be too hard to convert the examples in High-Tech to TL 9 versions if you want them in your campaign.

  3. aha! I've looked into missiles in gurps before, but I've been stymied by the scarcity of examples and by my lack of understanding about missiles (crazy how many kinds of weapons we describe with one word). That vehicles covers creation of missiles is a great revelation!

    1. Granted, using Vehicles to build missiles as, well, a vehicle would give more realistic results, especially at the more extreme edges. This however gives results that are (in my best North of the Boarder voice) good enough. And it's much a much quicker system which works better for a disposable resource like a missile.

      And yeah, the whole missile/rocket distinction is more of an English langue quirk. In Russian they're all called rockets with a qualifier to determine if they're dumb fire or not.

  4. Awesome stuff as always! I'll have to look at things for 20mm, 25mm, and 40mm gyroc rounds to see how they work out. Hey, maybe with gyrocs the OICW style weapon can work!

    1. Like rifle with 20mm gyrocs launcher on?

    2. Transhuman Space has it's base battle rifle have a 30mm gyroc launcher built in capable of holding 3 rounds.

  5. Huh, so they're using Vehicles 2e for their missiles? That's a relief, meaning missiles just need some transcription.

    1. For Ultra-Tech, it seems so. High-Tech didn't use a system for the stats like speed, weight and range since they just had to look up published values for them, just for warhead damage. In fact for the missiles I stated up for my fighter write up I did a few years back I just took modern upcoming missiles and assumed proper TL 9 versions would be a half step better.