Technology A Mathematical Approach to Energy Weapons

So recently we've been trying to sort out just how energy weapons should function and just how powerful they should be. I crunched some numbers and created a system that is admittedly complex, but answers just about any question you'd wanna know about energy weapons. So let's hop right in!

So just how powerful are energy weapons?

Well, it's actually quite simple. All you have to do is find a relation between the amount of energy used and the amount of force created in order to figure out how much damage your blaster is gonna be doing. For this, I took the muzzle energy in joules from numerous bullets in varying size, which will be used as our comparative force. I then converted the joules into watt-hours, a unit which measures the amount of energy used over time. This gives us the amount of energy used.

(Note: because I didn't like the sound of watt-hours, the energy units that will be used through the rest of this post are Galactic Thermal Units(GTUs), a made up term. GTUs are always equivalent to watt-hours.)

So now we have a reference for how much power is used to create an amount of force. Therefore, we are able to judge just how much energy it takes to produce an energy shot of comparable force. The table below provides real figures instead of a bunch of words, so you can more easily see how the force and energy compare based on caliber.

Spoiler: Data Table

Caliber | Joules | Galactic Thermal Units

22LR = 141j = .04 GTUs
9mm = 567j = .16 GTUs
45ACP = 835j = .23 GTUs
357 Magnum = 1087j = .3 GTUs
223 Remington = 1524j = .42 GTUs
7.62x39mm = 2108j = .59 GTUs
30-06 Springfield = 3820j = 1.1 GTUs
338 Lapua = 6734j = 1.87 GTUs
50BMG = 18,100j = 5.02 GTUs
(Anything larger than .50 BMG can be assumed to take an assload of energy and be terribly deadly)​

Okay, so... we can estimate power! Now what?

There's plenty of energy weapon types and plenty of ways they cause damage, so a simple power table won't cover everything. Unlike the ballistic weapons they're based on, energy weapons tend to cause mostly heat damage. For the sake of simplicity, i'm going to narrow down this heat damage to two distinct categories: penetrating and impact.

Penetrating heat damage is a trait i'd attribute more to plasma based weaponry. The plasma is able to form a cone with the object it comes into contact with and pushes thin jet of super-spicey plasma through the target. This will create a wound channel much like a bullets, except that everything will likely be nice and charred. Possibly cauterized as well.

Impact heat damage is simple, and I would say that laser based weaponry would be more likely to do this sort of damage. Once the projectile comes into contact with the target, the energy is simply dispersed around the point of contact as heat, burning and melting whatever it hit. This obviously will have issues penetrating, but would be highly effective against soft targets like flesh.

Okay! But what armor can stop these things?

Well, your typical kevlar vest won't be saving you. Ballistic plates will struggle to protect users as well, because plasma and lasers just ain't a bullet. What you need is a special kind of armor designed to deflect or resist energy shots. This sort of stuff is called ablative armor. So, sticking to my theme of basing my stuff off real-world data, i'm going to compare our ablative armor to the NIJ armor rating system. I'm going to omit a description of the NIJ system for the sake of brevity, so you may wish to google it for specifics. The gist is that i've based how much energy ablative armor can take off how much force regular armor can take. This data relates only to penetrating heat damage. Impact heat damage will be talked about later.

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Spoiler: Data Table

Armor Type | Round Tested To | Comparative Energy Absorption (Penetrating heat)

Type I Soft | .22lr | .04 GTUs Multi-hit
Type IIa Soft | 9mm | .16 GTUs Multi-hit
Type II Soft | 357 Magnum | .3 GTUs Multi-hit
Type IIIa Soft | 223 Remington | .42 GTUs Multi-hit
Type III Plate | 30-06 Springfield | 1.1 GTUs Multi-hit
Type IV Plate | 338 Lapua | 1.87 GTUs Single-hit
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To explain a few things, soft armor is comparable to kevlar. It's thin and flexible and often used in vest form. Plate armor is thicker and rigid, like a plate of metal would be. They're heavier and often need to be put in a carrier to wear. Multi-hit armor is rated to survive about five hits from the listed amount of energy, but any energy higher than what it's rated to is liable cause the armor to fail.

It is very important to note that this chart only shows the amount of energy it would take for penetrating heat type damage to break armor. Impact heat would require about double the amount of energy as penetrating heat in order to burn through the armor. For example, while Type II soft can take .3 GTUs from penetrating heat, it can take about .6 GTUs of impact heat. This isn't a real scientific figure, just something I figured i'd add.

Wow, that was too much to read. Are we done?

Nope! We haven't talked about magazines yet!

So yes, we know just about how much damage energy weapons can do now, but how many rounds can they fire? The easy answer is to just base the amount off firearm magazine sizes. A pistol magazine can hold about 10-15 rounds of 9mm. This means that something about the size of a pistol magazine can hold about 1.6 to 2.4 GTUs of energy. That means if the weapon is firing a projectile comparable to a 9mm round, it would be using .16 GTUs of energy per shot, and your magazine will run out of energy in about 10-15 shots. Amazing, right? The same theory applies to any magazine. As long as you know the approximate size and the amount of rounds it holds, you can judge just about how much energy you can squeeze out of a magazine of that size.

For everyone who wants a mathematical answer to this question, though, there's one within this spoiler.

Spoiler: Math

To estimate the size and resulting capacity of a power source for an energy weapon, I based my control measurements on a 10rnd 9mm Glock Magazine. After measuring them for their dimensions, I determined the magazines had a volume of 98,670 mm cubed. These magazines can hold ten 9mm rounds, which altogether equal 5670 Joules of force, which equals 1.575 of our imaginary GTU unit. Therefore, a space of 98,670mm cubed is able to hold 1.575 GTUs of energy. In other words, there are 0.00001596 GTUs per mm cubed (1.596 x 10^-5 GTUs per mm cubed). This conversion factor easily allows you to estimate a power source's potential energy based off volume and therefore find the capacity of any sized energy magazine.

Now are you done?

Yes, yes I am. Now, I truly believe this thread holds the definitive answer to just about anything anyone would want to know regarding the ballistics of energy weapons. I implore you lads to provide feedback, because if this is received positively enough we'll shorten it up for ease of reading and make it official.

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you get a gold star

Seriously though, this was a phenomenal guide to an otherwise elusive and hard to explain weapon alternative.

 

Like I said, a GTU is just a fantasy unit i'm using in place of watt-hours. GTUs are always equal to watt-hours.

The difference between 0.6 GTUs and 2.0 GTUs is the amount of energy being fired at you. 0.6 GTUs is comparable to 7.62x39mm, so similar energy to an 'assault rifle' round. 2.0 GTU is closest to the 338 Lapua, so you're talking more like a full rifle round powerful.

And honestly, I can't be assed to go into the nitty-gritty different types of energy weapons. There's about a billion different theories over a billion different sci-fi mediums. I avoided discussing them due to the fact that it would make a word wall on an already long blab, however, that doesn't mean i'd be opposed to possibly including a short thing on plasma vs. laser or something. Honestly, simpler the better. This thing's already a lot to swallow.

 

I figured that was up for interpretation. If your energy weapon is either burning people's faces off or burning clean little holes through people, you can assume just how bad of a burn/hole it'll be making based off the power of the comparative ballistic round. I have absolutely no knowledge as to how i'd properly figure out damage to organic things without making these weapons in real life and testing them myself, so... that leaves us forced to assume things.