Battletech Missile Equations Part II

I'm still trying to unwind Battletech's various missile systems. I guess I haven't talked about my aims. I'd like to develop a Grand Unified Theory of Battletech Missiles to create missile racks of any damage per missile, range, and missiles per shot. 

I'd also accept a Pretty Close Unified Theory of Battletech Missiles.

The Intuitive Approach

 

How do we intuitively know missiles work and can we apply that to Battletech missiles? The folks who made these things don't know much more than we do and they are sure to mix logical progression into game design knowledge to make missiles. 

We don't even have to assume that those are so different. Game design is assigning value to game pieces according to their abilities. How much is an additional 3 hexes of minimum range worth? How much is it worth to have a weapon that deals 12 damage in groups of 2 versus 18? Two tons? Three heat? 50% ammo capacity? Those values are calculated in with experience and, I assume, playtesting. We're just attempting to ferret them out.

So, what's in a missile? Fuel to get it where it's going. Guidance to follow a target. Payload to actually go "boom" at the end.

What's in a missile rack itself? Sensors to find the target and tell the missiles about it, plus telling the missiles when to shoot. Reloading mechanisms to keep new missiles coming. And what I can only call "blast material," which is the ability of the rack to withstand the explosion of the fuel as the missile is launched and to direct the missiles out of the tube so they start their flight straight and without hitting other missiles.

Now, I realize this isn't always the same. The Timberwolf famously has LRM 20s on paper and LRM 15's in the art. This is rationalized as the missiles firing in sequence with the tubes for the first five missiles reloading and firing again while the next ten tubes are firing. It's slick and it's a simple implementation of how the abstract rules of the board game cover a hand-wavey amount of detail in-universe. But it sucks because it defies simple analysis so it's fluff that we're going to ignore.

Missiles: Fuel, Guidance, and Payloads

The main intuitive reason that missiles fly 21 hexes instead of 9 or 38 is because of the fuel in them. The simple analysis is to say that 1 point of damage gains us about 12 hexes of range. That's how we turn SRMs into LRMs, right? That means that a missile system with 3 damage would have a range of -3. It's a start.

If we take MRM's description at face value, they have just as much fuel as an LRM and their range is shorter due to having less guidance and they're only half as big because HALF of an LRM's weight is guidance systems? 

That clearly doesn't work. If guidance was half of a missile's weight, we could fill the difference of an MRM up with payload and deal more damage with just a reduction in ammo capacity. Even if it's a fuel and guidance issue, that means that payload is still less than half of the missile weight and we can double missile size (and half ammo capacity) for additional damage.

Every time I've run the numbers on LRMs, MRMs, and SRMs with linear assumptions of range and damage, I get negative guidance coefficient. Now worse guidance doesn't make a missile heavier so that doesn't work.

Rocket Launchers aren't really counted in this. Rocket Launchers hold as much fuel as LRMs, but they're primitive tech. Even though you'd think inefficient explosives and rocket fuel would go the same way as NASA analog data readers. But it's a hard argument to make that really shit weapons should be lostech when the universe hinges on using regular shit weapons what because of all the lostech.

For convenience, let's assume Rocket Launchers have primitive propellant. Primitive albeit better than MRM propellant. After all, if rocket launchers' ranges which lower in proportion to missiles launched are due to flight interference of other missiles, then RL10 is the baseline, and the RL10 beats the pants off the MRM's range.

I feel that if there was a Grand Unifying Theory of Battletech Missiles, RL's would work roughly the same way most primitive techs do, albeit with greater flexibility. Perhaps even having a dial-able performance for each use like an omnimech.

But the intuitive approach for missile sizes is a dead end.

Racks: Sensors, Reloads, and Blast Material

If we go back to basics: LRMs and SRMs, we see they have similar weights per tube, about 0.5. From that we could determine that those factors roughly equal out. Sensors out to 21 hexes with indirect fire abilities, the ability to reload 20 missiles at a go, and the ability to have 20 missiles launch is about as efficient, on a tube-by-tube basis, as sensing out to 9 hexes over LOS, blasting two missiles 120% larger, and reloading two missiles a go. Sure.

MRMs have a whole different set of assumptions. Their sensors are obviously not as good, but they do a decent 5/7 the range of the LRMs, and blast twice as many missiles as an LRM rack. All for around 2/3 of the weight of a comparably sized LRM rack (3/5 for the 10's and 7/10 for the 20's).

Is 1/3 of a missile rack's weight sensors? Maybe. Streak SRMs certainly feel that way. Streak missiles are identical in weight to their non-streak counterparts, but the racks are 50% bigger (we're not counting Clantech). That's all sensor weight, given the identical range and rack size profiles.

Given MRMs' specs, it seems we can also rule out reloading weight being a significant portion of a unit's weight, 1/6 if we're just doing back-of-the-napkin math (-1/2 weight for substantial guidance and +1/6 for additional loading brings us to -1/3 weight).

"Blast Material" would be the bulk of the remainder. You could use MRMs as a scale of maybe pure blast material to calculate other types from. I haven't had any luck with that, as I haven't gotten around to doing the math.

Maybe part II of this series needs its own part II. We'll see.