F

The  is a Testbed Misc tank.

Design
The tank looks like Flail but it only has one segment before the tip, rather than Flail's 5 segmented chain.

Trivia

 * This tank's name is somewhat of a joke on Flail's name. Since Flail has 5 letters and the tank has 5 segments, this tank is just called F because it only has one segment.