@MWLL Keeper and Nano
Just some snippets from this page:
http://www.sarna.net/wiki/DropShipIn the BattleTech universe a DropShip is defined as any spaceship massing between 100 and 100,000 tons that is itself incapable of faster-than-light (FTL) travel.......
The mass range is given in the construction rules and reflects the fact that it is more or less impossible to build DropShips which are smaller than 100 tons or larger than 100,000 tons. Since DropShips are meant to be carried by JumpShips, a Docking collar is an implied neccessity and is automatically included in the structure of any DropShip......
The smallest known spaceship to meet the DropShip criteria is arguably the 200-ton K-1 DropShuttle, although it is generally classified as a Small Craft instead. The largest DropShip ever constructed is the 100,000-ton Behemoth, which due to its sheer size requires a second Docking collar on JumpShips, and is incapable of operating in atmosphere or planetary gravity. The biggest DropShip that can actually land on a planet and take off again is the 52,000-ton Mammoth.
The most common military BattleMech transport classes are the Leopard (one Lance: 4 'Mechs, 2 Fighters), the Union (one Company: 12 'Mechs, 2 Fighters) and the much rarer Overlord (one Battalion: 36 'Mechs, 6 Fighters); the most common Aerospace Fighter carrier is the Leopard CV class (one Squadron: 6 Fighters). .........
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For my sins If I wanted to move a Battalion with Armour and Aero support my dream team would be:
2
Excalibur - 16000 ton military spheroid, introduced in 2786. Combined arms transport (12 'Mechs, 90 heavy vehicles, 12 platoons). [Hopefully with 2 Medium Companys, or 1 Heavy/1 Medium]
1
Fortress - 6000 ton military spheroid, introduced in 2613. Heavily armed combined arms transport (12 'Mechs, 12 heavy vehicles, 3 platoons). Noteworthy for mounting a Long Tom heavy artillery piece; capable of securing its landing zone by itself. [for the Heavy/Assault or Command Company]
And a
Leopard CV - 1720 ton (obsolete)/1800 ton (upgraded) military aerodyne, introduced in 2581. Standard fighter carrier (6 Fighters) since Star League era. Looks decidedly different from the classic Leopard, having a round fuselage. Upgraded version launched in 3054. Now sure you could fit a 'Mech Battalion (without the Armour support or the Longtom Arty) onto an: Overlord 9700 ton military spheroid, introduced in 2762. Common BattleMech transport (36 'Mechs, 6 Fighters). But that's a lot of precious eggs in one basket and you need another DS anyways for the support vehicles. Costs more in Battalion expenses, but the combined firepower of the DS, with a RCT-style 'Mech Battalion beats the Overlords capability the number of doors for disembarking forces fast alone make this superior IMO..
EDIT: One thing to note though, despite what the fluff says that Longtom on the Fortress can only be deployed on the ground and not instantly either(maybe they nerfed it after playtesting)