In the 3050s, the Capellan Confederation was still struggling to rebuild itself after the destruction of the 4th Succession War followed by decades of mismanagement from an insane ruler. A new round of peaceful relations with the Free Worlds League gave them sudden access to Star League tech, and Sun Tsu Liao used this to order the construction of several brand new mechs for his forces, including the Thunder (the original TRO 3055 credits Romano with the Thunder's creation and reception of the mech despite her having been dead for three years at that point).
First walking off the assembly line in 3055, the THR-1L Thunder is a 70 ton mech built as a heavy cavalry machine. Powered by a 350 XL engine, it's able to reach a top speed of 86 kph while still retaining an impressive amount of tonnage for weaponry and armor. The use of 13.5 tons of standard armor plating gives it near-max protection while retaining plenty of internal space, as does the use of a standard chassis. All parts of the mech save the center torso are at their maximum protection. That makes it fast and tough, so what has it got in the way of weapons?
The primary armament is a Kali Yama Big Bore AC/20 in the right arm and right torso. I have absolutely no idea why two critical slots were left open in the right arm and two crits for the gun were stuck into the torso, but this design flaw means that it can only fire the gun into its front arc. Three tons of ammo sit in a CASE-protected bin in the left torso. For additional weaponry, a trio of medium pulse lasers are set one in each torso (right, left, and center), while an LRM-5 in the left torso provides token long-range firepower, with its ton of ammo also protected by the same CASE as the autocannon's. With one extra heatsink mounted in the engine, its 22 dissipation is capable of handling the mech's heat even in those rare instances when it fires the LRM pod with the rest of its weapons, with only 1 point of heat generated on a running alpha strike. At the time of its debut, people who forgot that the Saladin hovertank and Hammerhead ASF existed called it "the fastest AC/20 in the Inner Sphere."
The original was good, but technology shifted rapidly in the years since its debut so in the 3060s it was given a pair new variants. The first, the THR-2L, showed up in 3063, while the THR-3L appeared in 3066.
Both variants changed up things quite a bit. The engine was retained, but the armor and weaponry were both given an overhaul.
In both cases, the armor was replaced with the CC's new Stealth Armor. Definitely a good choice on the 2L, and the 3L gets benefit out of it but it arguably wasn't as necessary a change.
For weaponry, the 2L went with a modernized version of the 1L. The autocannon is now an LB 20-X, still fed by a three-ton bin in the left torso. The lasers now consist of a pair of ER Mediums located in the right and center torso, along with an ER small laser in the left arm. And realizing that a single LRM 5 isn't sufficient to intimidate even a Locust, it was replaced with a Streak SRM 6 for extra crit-seeking. A Guardian ECM controls the Stealth Armor from the right torso. The 22 heat dissipation of the mech is no longer close to keeping up with all its new weaponry and the Stealth Armor, but TSM was added to take advantage of that heat. Personally, I'm not a fan of combining TSM with streak missiles. It's really hard to manage your heat levels when you don't know whether or not the missiles will fire. In order to fit all this, half a ton of armor was removed, dropping its protection down to 13 tons. This was attained by stripping 2 points out of each arm and leg.
The 3L is mostly a variant of the 2L. The ER small is removed to restore armor protection up to the 1L's level, and the ER medium laser from the right torso was moved to the left torso while the Guardian was moved to the left arm. These changes were necessary to fit the enormous Arrow IV artillery missile launcher into the right arm and torso. Due to weighing a ton more than the LB 20-X from the 2L, it's only able to carry 2 tons of ammo, limiting its choices of munitions, but that's fine because the mech is also out of internal space for anything else. Technically this variant can run hot, but most of the time you're probably only going to be firing the Arrow IVs while keeping the stealth armor on to make it harder for scouts to find, so you shouldn't have too much trouble with heat. Arguably, the mech doesn't even need the stealth armor, but since 2 ER mediums and a Streak 6 aren't sufficient to defend itself at close range, having the stealth to make it harder to shoot you while you flee is a good thing.
One last variant exists and it's a substantial departure from the others. Showing up in TRO Prototypes, the THR-C4 debuted in 3083, after the Jihad, and it's quite different from the others. For starters, the engine is downgraded to a 280 X, resulting in a drop in top speed down to 65 kph, but mobility is increased by the addition of six improved jump jets.
The armor is the same 13.5 tons of standard plate as the original, with the same layout, but the internal structure is now Endo-Steel.
And for firepower, the big gun in the right arm is now a big missile, as it's home to a Thunderbolt 20 launcher with 4 tons of ammo. The Thunderbolt's more compact design means that it, and the ammo bin, and CASE II for protection can all fit into that arm. Three ER medium lasers now rest in the left arm, while a medium x-pulse later sits in its head. The mech's 24 heat dissipation is not sufficient to cover all this, especially while jumping, so watch the heat. And also remember that Thunderbolt missile warheads don't arm if the target is inside the missile's minimum range, resulting in them only doing half damage.
Fighting a 1L is simple in theory but harder in practice- shoot it before it gets into range of its AC. Which isn't all that easy when it moves 5/8 and is protected by basically-max armor. The 2L is similar, but further complicated by Stealth Armor. And if you do get close to either of them, take advantage of the blind spot they have in their right arc. With the 3L, it's an artillery mech- get close but watch for physical attacks. For the C4, bring an AMS- single missile tube weapons hate that thing. And get close enough that the minimum range insures that you'll only take a 10 point hit when the AMS doesn't shoot down the missile. As far as fighting in a Thunder goes, don't do it alone. The Thunder is a team player, it works best when it's got some buddies to watch its back and provide long range support while it closes.
And that's the Thunder in a nutshell.
