Loading the Canon: Loading the cannon.

I touched on the subject of heavy weapons in a previous entry, but it seems like a good time to touch on it again and expand it a bit. Specifically, I want to focus on vehicle weapons and how they're portrayed in the Firefly 'Verse vs how they work in the real world.

Now, what prompted this post was a brief discussion on the Firefly RP channel involving nuclear weapons and railguns, and I'm going to start with getting some frustration off my chest. Namely: "Look. If it really was as easy as 'Just use a rail gun and blow up the cruiser!' the Indies wouldn't have had their asses handed to them during the war."

Remember something. The Alliance has more, and better, tech than the Indies do, and the resources to deploy it. Seriously. Do you really think you're going to take out a cruiser with a single shot of an essentially unguided projectile?

Previously, we looked at what was actually shown in the series and BDM. In the series, that amounted to "Not very much." There were some missile shots and some auto-cannon and that's really about all we see. The only directed energy weapons we see is a modern Lassiter and the funky stun rifle things. Yes, there is the EtW antique Lassiter, but it's an antique and we never see it fire.

Through the course of the series, we see the Alliance's armed gunboats and a skiff during the flashback to the battle of Serenity Valley. We can safely assume the Cruisers we encounter are more than just carriers and are, themselves, well armed. But we never really see that. It's fairly safe speculation, but speculation nonetheless. Ship to ship combat just wasn't a major factor in the Firefly saga.

What little we see of the vehicle armaments is entirely missile and cannon, which actually makes sense. Kind of. Both weapon systems have one thing in common - they have a largely self contained delivery system. What do I mean by that? The entire store of 'energy needed to get to the target and to put the hurt on said target' is included in the mass of the ammunition.

The specifics of how the hurt is done may change depending on the round (HVAP (High Velocity Armor Penetrating) vs Shaped Charge, for example) but it's all part of a (mostly) self contained system. In the case of cannon shells, the propellant fires in the fixed weapon and spits the shell out the other end at high velocity. Thanks to Mister Newton, there's an equal amount of force imparted into the fixed part of the weapon as there is going into the shell spitting out the far end. Recoil is not, in fact, your friend in this case. The reason the shell leaves the weapon at high velocity and the ship doesn't move much is the relative difference in mass. The shell has a payload which may be anything from some kind of sophisticated explosive with a complex fusing mechanism to a simple solid metallic slug.

Cannon have the advantage of using relatively cheap, and compact, ammunition compared to missiles, and the inherent simplicity of the system. They have the disadvantage of recoil and the static mass of the fixed weapon.

Trivia: When the venerable A10 Warthog fires it's GAU8 30mm Gattling cannon, the recoil is slightly more than the thrust from one of the aircraft's two turbofan engines.

Missiles are remarkably similar, but rather than doing all the acceleration before they leave the vehicle, they take their engine with them. They have an even broader range of payloads than cannon do and don't have the rather annoying recoil. In fact, missiles potentially have much higher terminal velocities than shells do, carrying much greater kinetic energy to target. Missiles are also usually guided, so they can maneuver to hit, or otherwise inconvenience, their targets. Down side is larger, heavier, and more expensive ammunition.

As I said before, these are perfectly rational weapon choices given the levels of technology shown in the series. The BDM changed things up a bit with the addition of directed energy weapons on the Alliance spacecraft, and even a few being seen on the Reaver boats. Most notably, the directed EMP weapon they used on Serenity.

We don't really know much about the energy weapons we see - other than the classic SciFi 'visible beam' thing. Since the fight took place in the upper atmosphere of Mister Universe's private planet, we can assume the reason we see the beams is because of atmospheric ionization and not because they have crappy beam collimators.

Energy weapons have some interesting trade-offs with more conventional weaponry. The first advantage being an effective time-of-flight of Zero, followed closely by an absolute line of sight accuracy. It is much easier to put a beam of light on target than a physical object. Want an example? Take a laser pointer with you to the range next time and see how much easier it is to hit the bullseye.

Regardless. Energy weapons also have some disadvantages, many of which are blithely ignored in most Science Fiction. First, there is the matter of power. While it's entirely possible to use some kind of self contained "cartridge" to fire the energy weapons, akin to the Nuclear Pumped X-Ray Laser developed in the 20th century, it's almost never seen implemented or even implied. In nearly every case, the power for the weapons is drawn from the ship's main power supply, often routed through some sort of accumulator, then used to put hurt on the target.

Then there's waste heat. This is something else that's usually ignored, at least in general SciFi. Nothing is going to be 100% efficient. There's always conversation losses. That's why your car has a radiator: the engine only converts a fraction of the heat energy in the fuel into motion. The rest is lost as waste heat. Energy weapons have the same problem. Only part of the energy that goes into the weapon comes out the other end to form the beam, so the rest of that energy needs to be dissipated by the ship somehow. Unlike cars that can use convection to dump heat into the surrounding air, spacecraft have only two ways to get rid of excess heat: radiation and mass transfer. I'll save a discussion of that for a later LtC post, but it's an issue for directed energy weapons.

Now, how does this all tie back to Nuclear Weapons and Railguns? Good question.

"Railgun" refers to a specific form of electromagnetic projectile launcher. They're technically neither gun, nor 'cannon,' but are similar in that the launcher remains static while the projectile is sent down range at high velocity. In theory, they're relatively simple to make, but the engineering for an actual "weapons grade" system is quite complex. And, while they can achieve much higher velocities than a conventional gun, they have some of the same limitations of both conventional guns and directed energy weapons.

There's nothing specifically saying that these weapons couldn't be developed in the Firefly campaign. After all, the concept goes back to the early part of the 20th century and, by the early 21st, they were being considered as shipboard and tank weapons. But from what we see in-story in both the series and the BDM, they're never used.

Why not?

With a purely "This is fiction" perspective, it's fairly safe to say that they were never used because Joss never thought to use them. At least never in a place where we see them. It's possible the Rollers Zoe mentioned were armed with railguns, but we really don't know. We do know they used cannon. We know they used Directed Energy Weapons. We know they used Missiles. But railguns are pure speculation.

From the perspective that started this topic, namely "an easy way to take out a Cruiser" perspective, it comes back to Tactical, Engineering, and Physics issues.

The idea of a railgun being an easy way to take out a capital ship ignores a slew of issues. How exactly do you get the resources to build it? How do you power it? How do you deploy it? How do you aim it so you hit a moving target 500 kilometers off? How do you get the shot off before the Cruiser and her escorts turn your converted freighter to wreckage? How can you be sure you won't just spall off the Cruiser's existing anti-meteroid shielding?

As a Game Master, would I let my players do it? Yes. I would. If they went in with an attitude of "Just get a rail gun and shoot them down!" I'd hand them their asses just like the Alliance handed the Indies their asses at the Battle of Serenity Valley. If they actually worked out a plan and covered enough of the bases to make it a good story, it would be a different situation. They might still get their asses handed to them, but they wouldn't be blase about taking on a capital ship.

As for the nukes? This is already too long, so I'll have to get to that on another entry.