After writing up our recent ode to Missile Boats, it got me thinking about missile technology in the BattleTech universe. Not how each missile seems to do about as much damage as a modern-day bottle rocket, or how it can fly just about as far before running out of gas. No, it made me think about just how many of these missiles you can stuff inside a ‘Mech.
Think about it: a single ton of LRM ammo is 120 missiles. That seems like a lot considering a modern jet fighter has trouble carrying 10 of the things. Even the somewhat modern M2 Bradley Infantry Fighting Vehicle doesn’t carry more than 7 missiles in its magazine, so where does a ‘Mech get enough room for 120?
To find out, I decided it was time to do some math. But before we could bust out the calculator, I’d have to pick a missile-toting ‘Mech to be our scientific guinea pig. I chose the Mad Dog for its distinctive silhouette, and because it’d be relatively easy to calculate the volume of those boxy missile racks it has for shoulders.
Now that we have our ‘Mech, it’s time to see how big those missile racks are. We know that a Mad Dog is roughly 12 meters tall, and those missile racks are about a third of its height, so we know they’re roughly 4 meters in height. Eyeballing the thickness I’d get about 1.5 meters wide, and roughly another 4 meters in depth. That gives us a total volume of about 24 m3.
But that missile rack isn’t a perfect cube; it’s got an angled side, and all these fiddly bits cut out, so I’d say we’ve only got a triangular prism to work with. That halves the volume we have available, so we’re down to 12 m3.
Not to worry – we still have plenty of space to work with. Each of these side torsos has 120 missiles, and if we assume each missile to take up an equal amount of space we know that they have to take up at maximum 0.1 m3 per missile.
Now that we know how much volume each missile can take up at a maximum, it’s relatively simple to calculate the possible dimensions of a single LRM. Since the height and width of a missile are the same (since it’s a cylinder, they’re both just going to be the diameter of the missile), the only question is how long the missile could be.
Let’s say the missile is 1 meter long (which is actually close to the length of a modern-day missile). The formula to work out the diameter of the missile would be:
0.1 m3 = L x W x H = 1 m x W x H = 1m x (W2) = 0.316 m
0.316 m is roughly 12.5 inches or a little over a foot in diameter. For a 1 meter long missile, a diameter of a foot is a bit chubby (maybe more closely approximating an artillery shell than a missile) but totally within the realm of possibility.
But we know that side torso isn’t just dedicated to missile ammo. There’s the LRM-20 launcher itself, a few crits of XL engine, and double heat sinks stuffed in there too. So let’s say that there’s really only half the available volume for missile ammo. The formula then changes to be:
0.05 m3 = L x W x H = 1 m x W x H = 1m x (W2) = 0.224 m
That still gives us a 1-meter long missile with a diameter of close to 9 inches. If we compare that to a modern-day missile, like, say, the AGM-114 Hellfire (which is 64 inches long and 7 inches in diameter), we’d see those numbers are roughly in the same ballpark and still very reasonably missile shaped. Cool.
Of course, we should also consider the fact that each missile isn’t a perfect rectangular prism, and each cylinder can save space by stacking in between the cylinder below it. My math wizardry is far from able to calculate how much space we’d save, but I’m sure one of you mathematicians could figure it out in the comments below.
So it seems a big ‘Mech like a Mad Dog doesn’t have any trouble carrying around 120 missiles, but what about a smaller missile ‘Mech? Let’s take a Javelin and see if it still can carry around a full complement of missiles like its heavier brethren.
Once again, we have to figure out how much of a vaguely man-shaped ‘Mech’s chest can be devoted to missile ammo. I don’t have an exact height for the Javelin, but since it’s a lighter ‘Mech I assumed it to be around 8 meters tall. Given that height, those boxes in the chest look to be around 1 meter wide and 1 meter high, and it has a 2-meter depth to its chest. Thus we get an available volume for missiles of 2 m3 for a single ton of SRM ammo, which is 90 missiles, and each missile can take up 0.0222 m3.
Since these are SRMs, let’s assume they’re going to be shorter than the long-range missiles and give them a length of half a meter. Using the same formula as before, we get a 0.21 m diameter missile or 8.26 inches. That’s still very reasonably missile shaped even on a tiny ‘Mech, and once again if we’d stacked those missiles properly we’d have even more volume available for an even bigger missile.
Before we all start celebrating this miracle of a single aspect of BattleTech that makes physical sense, there is a condition where a ‘Mech’s capacity for missile ammo starts to break down. When a chassis starts to horde ammunition, such as the Archer and its 4 tons of ammo, suddenly you go from hurling missiles to throwing shoe boxes that explode.
But hey, I’m happy to find out that my favorite ‘Mech designs can carry as many missiles as they say they can (unlike autocannons, which still make no sense).
And as always, Mechwarriors: Stay Syrupy.
Math madness. Better you than me. LOL.
Great article though!
The designers/artists drawing the’Mechs don’t care much for scale. When I compare the LRM launchers of the original 3025 Archer artwork with something like the Scylla, where the arm launchers look bigger than a Dropship exhaust, there’s quite a difference in scale. The launcher on the Vindicator looks like a teeny hatch.
And I really don’t want to think how the Zeus’s ammo feed works. That’s a special kind of madness.
Have you seen the old OmniMech blueprints? They show diameters for different Clan LRMs and SRMs from 120mm to 200mm. I’d say your math was pretty accurate.
I wish you could turn this into a math lesson.
This one of my ( one hehe ) pet peeves about the BT multiverse. Somehow we have fusion engines and particle cannons but our ballistic and missle teck is about 1944.
The math works out to about a 16 lb rocket for a LRM and 27 lbs for a SRM. With fuel and body that leaves very little weight left over for stuff that goes bang. No wonder they do 1 and 2 points each!
It’s a pet peeve of mine as well, but there are certain factors that play into why this is. Until the collapse of the Star League, AMS systems were fairly common, and we know they’re relatively good in Battletech (all things considered) so single, expensive missiles were easy fodder for them. A cloud of cheap missiles has a better chance of more getting through.
They’re also comparable in terms of size. Given most measurements in Battletech are metric, we can probably assume the tonnages are also metric tons or about 2,200 lbs per ton. An LRM is a little over 18 lbs in that calculation (2200/120), where an SRM is about 22 lbs (2200/100). Given the casings of these things are meant to be light, it’s probably safe to assume most of the metal is going to be around the rocket motors and plastic will be used elsewhere – high bulk, low weight.
There’s also the economics of their manufacture. We know SRMs are dumb-fire missiles that are just explosives, basic guidance fins and fast-burning rocket fuel while LRMs trade their payload weight for guidance systems and fuel. As such, it’s easy to crank out lots of cheap missiles knowing you can lay them down in waves rather than single, expensive missiles that might be good against one specific thing.
It’s not entirely realistic, granted, and we know people will innovate when need drives them but I suspect that is part of the semi-dystopian elements of Battletech as well, especially during the height of the Succession Wars when all the advanced tech was being lost and/or suppressed.
I go with the assumption that the “artwork/illustrations” are “fanciful” and the missiles in Battletech/MW are MUCH smaller (making sense of the light damage and ammo capacity for missiles).
The Mk 4 Folding-Fin Aerial Rocket, used by many US aircraft, is a very close size & weight to what a “typical” LRM sized missile would be. 4 feet long, 2.75 inch diameter, and each weighs 18.5 lbs. Given that a metric ton is roughly 2,200lbs, 120 MK4 rockets would weigh 2220lbs, so a very close weight. Although, with 1 ton of missiles taking up 1 crit slot the math doesnt work when factoring in the bulk required. There has to be some belt-feeding system and seperators so the explosives aren’t rattling against each other as the mech moves and remaining missiles reload after a salvo has fired. Just 2 explosive warheads banging against each other could detonate the whole ton of ammo. Imagine the impact a jumping mech has upon landing.
I just look at it like there has to be balance with weapons because this is a game. Honestly, a machine gun weighing half a ton would have a range far exceeding 3 game hexes or 90 meters. The MK4 rocket has an effective range of 3,400 meters or 113.3 game hexes, not the 21 hex range of an LRM. Being military and having a gaming group that was mostly military and familiar with real life weapon systems, we realized game tech and reality dont mesh if you want to maintain workable game balance.