In the spirit of the Kanga, which caused people to say "wait, you put those on what?", I was messing around with vehicles and thought the Inner Sphere in 3025 really needed more options for long-range fire support. Now that I made them, I really see no reason why these vehicles wouldn't see service in any era.
Thumper VTOL (so called because of the distinctive thump-thump of its rotors... and the Thumper artillery it carries)
30 ton VTOL
4 tons -- 70 rated internal combustion engine
3 tons -- internal structure
3 tons -- lift equipment
1.5 tons -- control equipment
1.5 tons -- armor (24)
17 tons -- Thumper artillery piece (40 ammo)
823,000 C-bills
7/11 movement
Front -- 8
L/R -- 5
Rear -- 4
Rotor -- 2
1 Thumper artillery piece with 40 rounds (Front)
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The Thumper VTOL was created because of the pressing need for artillery support for fast moving attacks. It also solves the problem of slow-moving heavy artillery pieces being captured by light battlemechs, and makes counter-battery fire nearly useless.