Engine Selection & General Notes
Most of the Catapults have an engine cap of 315. There is a ton-and-a-half cost to increment from an XL300 to an XL305, though, so with rare exception, the XL300 will be the go-to engine. The most notable exception is the Jester, which has a 355 engine cap, and so is best fitted with an XL350 to provide additional space for heat sinks and a 94kph top speed.
Beyond the engine, time in the Catapult taught me something else applicable across the entire line of Catapult variants. Like the Nova, people take aim at particular components on the Catapult, but where in the Nova it was the legs, the arms/ears of the Catapult are what draw fire. This led me to two design goals, with respect to the arms, one of which is not terribly intuitive.
The first and obvious design goal is to avoid putting weapons on the arms, whenever possible. If people are going to pluck the ears off, then I'd rather cram all of my meaningful equipment into the torso. The less obvious design goal is to try to put half a ton of armor on each empty arm. If hostile mechs are going to spend the time plucking the arms off, then I'm going to make sure that the process takes a little more time, before they can change their focus to my torso. Maximize the effectiveness of the enemy's bad habits.
When I started working on the Catapults, the K2 build was pretty easy to figure out. UAC5s were strong; large lasers had good range synergy with UAC5s, and the rest of the work was tuning the balance of armor, engine, and ammo.
My final tune of the build wound up looking like this. Prior to the UAC5 nerf, this was a consistent mid-to-long-range fighter. Since the nerf, I've been trying to recapture the magic.
As I mentioned in the previous weapon balance thread, I mentioned that my go-to replacement for UAC builds is Gauss. That's not a brilliant replacement for the K2, since one Gauss rifle and two large lasers is underwhelming damage over time. Replacing the large lasers with large pulse lasers results in a better mid-range build, but it's a bit disappointing not being able to fully utilize the Gauss rifle's range.
If we're going for mid-range, it's worth considering replacing the Gauss with an AC10. This draws your effective range in closer, owing to the lower projectile speed of the AC10, but the large pulse lasers had done that already, so there's not much of a sacrifice occurring there. This feels like the closest performance match for the original UAC5 build, giving up some range, in favor of reliability.
I didn't stop there, though. There's two ballistic hardpoints, and I wanted to make use of them both, dammit. The most incremental change up from a UAC5 is an LBX10, being two tons heavier per gun (and having more efficient ammo bins). The problem is, I still don't like the LBX10, and an AC10 is three tons heavier than a UAC5.
If you're really determined, you can find the tons for a pair of AC10s to accompany the large lasers. The armor shave is too aggressive. You're not likely to have an XL295 just lying around, while an XL300 could be used in a number of other mechs and builds, making this an expensive build. (Plus, I just don't like sacrificing mobility for tonnage, if I can avoid it.) Oh, and for two AC10s, 70 rounds of ammo is a bit sparse. That said, while you might run out of ammo fairly often, two large lasers can put out 300 damage with relative ease.
Remember the Cyclops-10q? Do the same thing. Until SRM4 spread gets nerfed, use the ASRM4 version.
It's worth noting that this can be a tough variant to use effectively. All of your hardpoints are in the ears, so there's no avoiding putting your weapons there, and little that you can do to avoid having hostiles pluck those ears off. It's really essential that you flank effectively and coordinate your attacks with those of the rest of your team, so that you can do as much damage as possible, before being disarmed. Investing weight and C-bills in the XL310 engine gives you an extra bit of mobility that will be a lot more valuable than an extra heat sink or another ton of ammo. The heat sinks in the arms of the SRM4 build are there primarily to crit-pad the launchers, reducing the likelihood of them being destroyed, prior to the arms being knocked off completely.
Part of the reason that I didn't pursue any all-energy builds on the K2 was because the Jester is better suited for such builds, with its higher engine cap. If you don't want to drop MC on this hero variant, then some Jester builds can be transfered over to the K2. That said, if you wanted a larger Hunchback 4P with jump jet capability, then the Jester will serve you well.
One of my early builds added a couple of flamers to the trio of large pulse lasers that serve the HBK-4P so well. The range differential between the two weapon systems and the ability to control the range of engagement afforded by the large engine meant that the flamers sat idle in most fights.
Setting that build aside, I tried a more traditional energy brawler. Aside from the tendency of the ears to fall off, owing to the aggressive armor shave, this is a really good build. The short beam duration of the pulse lasers allows you to spread damage effectively, and the tons and tons of heat sinks let you keep belching out beams in an extended fight.
Despite the pulse brawler's effectiveness, I kept experimenting and settled on another triple-large pulse build. This is a little less powerful in a close-range brawl, but with quirks and modules, the large pulse laser's optimal range gets pushed out to 438 meters, giving you a pretty dangerous mid-to-long-range poke. The flamers of the first build are traded for another heat sink and another jump jet, which help performance on the margins. More importantly, though, the arms are empty and armored, fulfilling the decoy role better than most any other build highlighted in this post.
I do not own the C1, C4, or Butterbee. These are all mixed energy-missile variants, with the second hero variant, Butterbee, having the obviously superior hardpoint configuration. (Power creep? Pay to win? You decide!) The C1 and C4 will obviously facilitate hybridizing Jester and A1 builds. The C1 can run with a laser brawl configuration with some SRMs to add burst damage, and the C4 can run an SRM build with lasers in the center torso to prevent it from becoming totally useless when its ears are clipped.
Personally, if I was going into the Catapult without wanting to spend MC, I'd swap the Jester for a C1. It doesn't have an energy heat generation quirk, but its hardpoints allow the C1 to mimic triple-large pulse build. The variety made available by the missile hardpoints in the arms is icing on the cake.
Back when mastery packs went on sale for the first time ever, I gave several of them a good, long look to see what was worth spending some of my MC (banked from the Founders' Program!). Most of the packs include one or two good variants, with a red-headed step child, for which you will unlock basic skills, before immediately abandoning it.
Prior to the UAC nerfs, the Catapult was one of the exceptions. The A1 has a bit of a problem with its tendency to be disarmed, but that vulnerability is balanced by the ludicrous amount of damage that SRMs can quickly pump out. I think the K2 was hit pretty hard by the latest round of weapon balance adjustments, since there's no easy replacement for the UAC5s in that build, unless you want to run a pure energy build.
The Catapult is a launch chassis that has fared well over the years. While the Hunchback and Atlas have clearly superior competing chassis now, the Catapult still outperforms a number of 65-ton mechs and other heavy chassis. I'd like a higher engine cap (325 or 350) in the non-hero variants, but the 80 to 83kph of an XL300 or XL310 is quick enough to not feel gimped, and the energy-missile variants have enough hardpoints to make threatening weapon loadouts for the current environment.