Well, if there is one thing over here at GURB that we love, it's guns!
And what's the ultimate form of gun love? One that can fire really, really, really fast!
In this (somewhat late) Valentine present to my readers I not only go over how to stat up some ultra tech energy gatling guns but I go back over how sustained fire for energy weapons worked in Ultra-Tech and bring them more in line with the more advanced rules found High-Tech.
Got nothing but love for ya guy!
Ah, the gatling gun. There is just something undeniably badass about them. Something that's just fundamental. It's not just that they have a ludicrously high rate of fire, it's the whole spectacle of HOW they can reach that rate. That spinning build up, that ripped linen burp of its fire, the crescendo of falling cases. It's enough to make a grown man squee like a school girl.
First developed by Dr. Richard J. Gatling during the American Civil War, the original Gatling M1862 was a .58 caliber, six barreled, hand-cranked machine gun and a huge advance in firearm development. By using a rotary action it was able to obtain an extremely high rate of fire and by using multiple barrels it was able to sustain this rate of fire by splitting the heat build up and wear across them. The weapons was quite the success and several improved version were developed as well as several close copies (including even an early attempt at an electrically power one made in 1893!). As effective as they were, they did suffer from being mechanically complicated and expensive weapons. Do to this, once gun designs and material manufacturing reached a point were a single barreled weapons could reach similar rates of fire they quickly supplanted gatling style weapons since they were lighter, cheaper and less complicated making them more attractive to military buyers.
It wasn't until the post world war two late 1940's and the beginning of the jet age did the concept see a renaissance. Do to the super high speeds that jets were starting to reach, in order to for the gun to stay relevant as an aircraft based weapon you were going to need one that can not only put a lot of lead on target but one that can keep it on target as long as needed. Needless to say this is the gatling guns bread and butter and with the development of General Electrics T171 (later adopted by the USAF as the M61) Vulcan 20mm six barreled electrically cycled gattling cannon the concept was revived giving us such dakka over kill such as the reigning king of overkill, the GAU-8 Avenger, the GE M134 "mini"gun and heck, even the Ruskies got in on the love with such gems like the minigun like GShG-7.62 and the massive GSh-6-30 (Russian Avenger assemble!).
And of course this love for ridiculous levels of firepower has carried over to games, both tabletop and digital bringing the concept into the speculative future and giving us such lovely purveyor of volumetric death such as the various laser gatling guns from the Fallout series to the tau's plasma burst cannons from Warhammer 40,000.
Ok, with that little history lesson out of the way let's get down to why you guys are here. How to stat up energy gatling guns in GURPS.
There are two ways of going about this, the easy way and the crunchmeister way.
The Easy Way
Just use the rules found on Ultra-Tech pg. 133 and optionally treat any energy weapon that has ROF4+ as being a "gatling weapon" as per Blaster and Laser Design System (Pyramid 3/37 pg. 12). Just treat how many barrels you energy gatling weapon has as a special effect. No fuss, no muss, no coconuts!
Well, if you're a long time reader of this blog (wait... can I even make the claim I have long time readers yet heh?) chances are this is the option you want to explore.
Before we can get into more detail on how to handle energy gatling weapons, first we have to give a reason for needing to use one. This means we need to upgrade the relatively oversimplified rules for sustained fire that Ultra-Tech uses. Thankfully High-Tech already did much of the heavy lifting for us already with its Sustained Fire rules found on pg 85 and 86. Said rules give a good rule of thumb for how many shots per minute for both normal firearms and the beefier barrels of machine guns, not only for sustained rapid fire bursts (rarely used by professional shooters but fun!) but also more controlled assault and sustained bursts. It also conveniently covers how the effects of better materials at higher TL improve this rate of sustained fire and how less advanced materials at lower TL lessens it and as an added bonus it also covers how properly maintaining and cleaning your weapon can buff this rate even further!
So yeah, this makes things a bit easier.
Now energy weapons do have one thing that does give them a slight edge here over standard chemically propelled weapons, that is they get more efficient at higher TL which means they generate less waste heat which in turns means that each firing is less stressful on the barrel. This benefit however is modeled by the fact that they get lighter at higher TLs since they need to devote less mass to cooling.
However, improved materials at higher TLs still do boost how much long of a burst a given weapon can sustain.
Ok. For a given type of energy weapon at its TL of introduction (see here for some guidelines on what TL counts as a given energy weapons intro TL), with a bog standard barrel, you can sustain:
Sustained Fire for 600 shot.
Assault Fire for 300 shots.
Rapid Fire for 150 shots
See pg 85 and 86 of High-Tech for an explanation for what these terms mean.Though keep in mind that these are just averages.
Multiply these values by 2/3rds for early versions of a given energy weapon that are available one TL early, by 1.5 for a TL+1 version and double the sustainable rate of fire for TL+2 and higher versions.
When designing weapons for your campaign don't think you need to make every gun stick to these numbers. To add some flavor feel free to have some weapons that are able to have slightly higher levels of sustained fire and some that have a little bit less.
Over Heating the Weapon
If you exceed these values drop the weapons Malf. rating down one level (and -2 to Acc if a plasma weapons). If you let the weapon cool down for at lest 15min these penalties will pass but if you exceed the sustainable fire limit by 3 times or more this penalty becomes permanent and make a HT for the weapon, on a failure it burns out and needs to be replaced.
For a greater sustained rate of fire, heavier or more barrels are needed. We'll cover more barrels in a second but if you want an energy machine guns use the following options.
Standard Energy Machine Gun Barrel
Increase weapons weight and cost by ×1.5 but double the weapons sustainable rate of fire.
Heavy Energy Machine Gun Barrel
Increase the weapons weight and cost by ×2 but quadruple the weapons sustainable rate of fire.
One common trick used by real machine guns to let them keep firing without risking barrel damage is to give them quick swap barrels. If you want to design an energy weapon that can swap barrels, assume that an extra barrel or focal array is half of the weapons weight and cost. It takes 5 ready actions to swap a barrel at TL9, at higher Tech Levels better modular technology drops this to 4 ready actions at TL10 and smart matter modules drops this to 3 ready actions at TL11+.
So what advantage does having a gatling action give energy weapons? As I said earlier, for conventional firearms, a gatling action lets a weapon cycle rounds faster and lets it sustain fire for longer by using many barrels.
With energy weapons, cycling the action isn't a problem since it's all electrical (well, with the exception of plasma weapons) with the limiting factor being how robust of a power supply it has.
So this just leaves the increased ability to sustain fire. While this limits the usefulness of this option for energy weapons, it is is still a very viable option if you need a weapon that needs to be able to fire continuously (such as a support/suppression weapon or a point defense gun) since, while still fairly heavy, adding more barrels with the gatling option is lighter and cheaper then making if you just make a normal multi-barrel one or just try to give it a even heavier barrel.
With this out of the way, lets get to the stats!
The following is an unofficial supplement for the Blaster and Laser Design System from Pyramid 3/37 which you will need to make use of these rules.
Step1: Design Your Energy Weapon as Normal
Start out by building your energy weapon as normal. As usual you should think of its purposes and why it needs to be a gatling weapon (outside of the cool factor heh). Just keep in mind that you'll want a high rate of fire. See this post of mine if you want a greater level of options for choosing your weapons rate of fire. Also keep in mind that gatling weapons don't need super heavy barrels so to save weight, a normal or a standard energy machine gun barrel is all you usually need to save weight.
Example: Let's say we want a man portable, high rate of fire squad suppression TL10 Gatling Laser that can be carried by normal soldiers or mounted on a vehicle. It is going to look like the classic movie man portable minigun but to keep it's weight reasonable we set it to do 4d+1(2) burn damage, have an F of 1 and a ROF of 30 which gives it a G of 2.5. To keep weapon weight low we will leave it with a normal barrel. We also decide that powering with 8C cells which gives it 252 shots sounds about right. This gives us a weapon with a base empty weight of 8lbs and base loaded weight of 12lbs.
Step 2: Choose the Number of Barrels
Figure out how many barrels you will need. More barrels will let you fire for longer but will also make your weapons heavier and costlier as well. Also the heavier things are, the more power is needed to spin the action.
Multiply your weapons Sustained, Assault and Rapid Fire rate by the number of barrels.
Example: We want a decent level of sustained fire but we also need to keep it man portable so we choose three barrels, which is the minimum needed for a gatling action. Since TL10 is the introductory TL for laser weapons, the Gatling Laser will have a Sustained Fire of 600×3 or 1,800 rounds, Assault Fire of 300×3 or 900 rounds and a Rapid Fire of of 150×3 or 350 rounds.
Step 3: Figuring Mb
Once you have figured how many barrels you are going to use, you will multiple the weapons empty weight by Mb which accounts for the extra weight of not only the extra barrels but the rotary mechanism and motor needed to spin the barrel.
Mb is 1 if the energy weapon is not a gatling weapon or number of barrels×0.45 if a gatling weapon. Mb must be at lest 3.
Example: Since we want to give our Gatling Laser three barrels it will have a Mb of 3×0.45 or 1.35 which brings our empty weight up to 10.8lbs and loaded weight up to 14.8lbs.
One down side of a gatling action is that is needs power to work. While there are works around to this such as using a pyrotechnic charges, since energy need electricity to run anyways it's usually just simpler to use power cells.
Power Requirement = Gw × ROF × 0.00054kW
Gw is the weapons empty weight
ROF is the weapons rate of fire.
Example: With a ROF of 30 and a empty weight of 10.8lbs, our Gatling Laser will need 0.18kW per second of fire. We add 2 B Cells to the Gatling Laser letting it fire for 400 seconds before needing to be recharged and adding a negligible amount of extra weight to the weapon.
Accuracy and ST Requirements
While it is possible to make a rifle form gatling weapons (Ultra-Tech even has an example, the Gatling Carbine, on pg. 136 and 37), most classic gatling weapons would be stated as mounted weapons (aka cannons). If modified to be man portable then re-figure its Acc as if its a rifle and multiply its ST by 0.7 and add a dagger. Increase a plasma guns Rcl to 3 and figure its new ST as old ST ×0.75. In either case the skill to use it stays Gunner (Beams).
Option: Carrying Handle
Modifying a gatling weapon to be man portable usually involves adding a handle strong enough to support it as well as an firing mechanism. This adds 4lbs and $800.
Example: Since we're going for the classic minigun feel we're going to want to add a handle. This adds 4lbs the weapons empty weight bringing it up to 14.8lbs and adds $800 to the cost.
Using this for System for Conventional Firearms
Since we do not have an actual gun design system yet for 4th edition I decided to focus this article on energy weapons since we do have system for them. That's not to say you can't use this to stat up some extra conventional gatling guns!
This system does let you converted normal guns that have been stated up and as gatling guns. The only difference is that normal guns don't need a power supply so having a larger rate of fire doesn't necessarily require a heavier weapons (though you will want a more rugged barrel). All you do is take the empty weight of the gun you want to convert, give it a heavier barrel if you want and multiply it's empty weight by Mb.
Example: Let's take the 7mm Assault Carbine from Ultra-Tech (pg 136 and 137) and turn it into a 6 barreled gatling gun. The empty weight of the Assault Carbine is 5.5lbs. Let's give it a Standard Machine Gun barrel increasing its empty weight to 8.25lbs and with 6 barrels we get a Mb of 2.25 giving us a weight of 19.8lbs. Let's throw on a handled for another 4lbs giving us a final empty weight of 23.8lbs. That lines up pretty well with the 23lbs empty weight of the 7mm Minigun from Ultra-Tech (pg. 136 and 138)!
Gatling Laser (TL10)
This tri-barreled gatling laser is designed to be used as a heavy machine laser to cover troop advancement and keep the enemy pinned down and suppressed. It can maintain a sustained fire rate of 1,800 rounds, an assault fire rate of 900 rounds and can rapid fire for 300 rounds straight letting it empty its entire power cell in one long burst. It's gatling action is powered by 2 built in B cells that run the weapon for 400 seconds. The laser its self is powered by an cylindrical 8 stack of C cells which are are inserted in the left hand side of the rear housing.
With its light weight and high rate of sustainable fire, the Gatling Laser is the perfect support weapon whether you're a royal space marine or a lone wanderer exploring the radioactive wastelands of Old Vegas.
GUNNER (BEAMS) (DX-4, or other Gunner-4)
TL Weapon Damage Acc Range Weight ROF Shots ST Bulk Rcl Cost LC
10 Gatling Laser 4d+1(2) burn 12 790/2,400 18.8/8C 30 252(3) 9† -7 1 $11,800/$80 1