Incremental Improvement - the Tank Mark IV

While the Tank Mark I had been an impressive vehicle when it debuted, it was clear very quickly that it had significant flaws, some easy to fix, others less so. It was slow, difficult to maneuver, had a tendency to damage its heavy guns, had only 14-round strips for the Hotchkiss MGs, was thinly armored enough that special rifle bullets could penetrate the front armor, and had fuel tanks perched above the driver at the front of the tank. Clearly, improvements were needed.

The Tank Mark IV improved on some of these flaws. It was only a tiny bit quicker (6.4 kilometers per hour instead of 6.0) and no more maneuverable, but it attempted to address the other problems. The heavy guns were shortened from 40 calibers to 23.5 calibers, keeping them clear of obstructions except in the most extreme situations (coincidentally, it also improved armor penetration, as the shorter 57mm had thicker barrel walls, and could use a larger powder charge). The machineguns were swapped out for air-cooled Lewis guns. While this greatly improved ammunition capacity to 97 rounds per drum, the guns did have a tendency to overheat because tanks do not develop nearly as much of a cooling airstream as aircraft. The frontal armor was thickened by 2 millimeters (which has no effect at T2K's level of granularity), and the fuel tanks were moved from the top front to the bottom rear of the tank, using a vacuum pump rather than gravity feed. A typical ammunition load for the 57mm cannon was 180 rounds of HE and 152 rounds of AP.

Surviving examples: There are a few surviving Mark IV Tanks. The Bovington Tank Museum has an operational Mark IV Male, "Excellent." There is also a surviving (but non-running) Male in Belgium, and five non-running Females (2 in the UK, 1 in France, 1 in Australia, and 1 in the United States).

Tank Mark IV Male
Fire Control: 0
Stabilization: None
Armament: 57mm L/23.5 in left sponson, 57mm L/23.5 in right sponson, Lewis Mark 2 in left sponson, Lewis Mark 2 in right sponson, Lewis Mark 2 forward
Ammo: 332x57mm, 6111x7.7mm
Fuel Type: G, A
Veh Wt: 29 tonnes
Crew: 8 (commander, driver, 2 gunners, 2 loaders/machinegunners, 2 gearsmen)
Mnt: 15
Night Vision: None
Tr Mov: 7/3
Com Mov: 3/1
Fuel Cap: 318
Fuel Con: 40
Config: Veh
Susp: T: 6
HF 2
HS 1
HR 1

Tank Mark IV Female
Changes:
Armament: 2x Lewis Mark 2 in left sponson, 2x Lewis Mark 2 in right sponson, Lewis Mark 2 forward
Ammo: 26384x7.7mm
Veh Wt: 27 tonnes
Mnt: 14