MBT(MR)

During the development of what would become the XM551, it became apparent the design it was realizing did not suit the concept of a Main Battle Tank as originally described. So a new tank had to be designed in order to better suit these requirements and a request was made by the US Continental Army Command in March 1960. Referred to as the MBT(MR), the three versions of the basic concept were presented by Ordnance later in October.

Two versions were powered by the AVDS-1100 engine and XTG-411 transmission, one of which fitted with experimental radiological protection systems. The third version was an unconventional driver-in-turret design using the liquid-cooled LVDS-1100. All versions used an integrated commander's station, allowing the commander to align the gun with his own sight, and included a secondary set of driving controls for use in an emergency.

Additional concepts for the MBT(MR) included using a modified T95 armed with the 152-mm XM81 Gun-Launhcer, using the 105 mm Gun M68 standardized for the M60, various smoothbore weapons ranging from 90-120 calibers, the British XM23 (L11A5) 120 mm gun, a TOW weapon system, and even an externally mounted gun pod.

While no pilot vehicles were ever constructed, the entire MBT(MR) program served as the basis for multiple experiments and test rigs. In addition to armaments, several different turret configurations and engines were also trialed. Eventually, results from the program would create the M60A2 and the MBT70.

This tank can be thought of as a larger version of the XM551. The gun handling should be relatively similar, but the main differences are with its armor and traverse. Traverse should be considerably worse, making the tank seem sluggish and unresponsive. In exchange it gets a conventional armor profile. However, there is also a bar-cage option that could serve for the secondary hull option, and the second turret could also receive this armor upgrade. It would better differentiate the MBT(MR) from the M60A2 I intend to introduce. In addition, because of the unique properties of the commander's station, the aim time could be considerably better compared to the XM551 and M60A2, despite the poor dispersion values.

A bar-armor installation for the conventional MBT(MR) configuration.

I think a 90 mm gun could serve as a standard stock option. The armor profile and speed aren't described by Hunnicutt, but I think it's safe to assume they'd be similar to the T95 Medium. In fact, the hull and turret are essentially modified versions of the T95E8. The armor profile itself should be unremarkable for the given tier, but the cages do help provide significant protection against HE and HEAT. I've also included all the various engines proposed, but the top engine could possibly be removed if it's simply too powerful. 

Guns: 90 mm Gun M41; 152 mm Gun-Launcher XM81 (conventional); 105 mm Gun T254; 105 mm Gun M68

Engines: Continental AVDS-1100 (550 hp); Continental AVDS-1100 VCR1 (700 hp); Continental AVDS-1100 VCR2 (850 hp); Caterpillar LVMS-1050 VHO (1000 hp)

Turrets (Turret Armor (mm)): Integrated Fighting Compartment (??/??/??); Integrated Fighting Compartment (Caged) (??/??/??)

Suspensions/Alternate Hulls, Total Weight (metric tons): Main Battle Tank (MR) (39); Main Battle Tank (MR) Caged (39.91)

Hull Armor (mm): ??/??/??

Top Speed: ?? km/h

Crew: 4 (Driver; Gunner; Loader; Commander/Radio)



Parent: TS-4/3
Children: T95 TOB-TR
See Also: M60A2, MBT-70 3AS, MBT(MR) 120, T95E8 TR

Sources:

Hunnicutt, R. P. Abrams, 2015.