Dalluhan main battle tank Direlba-51
Background
While Dalluha remained neutral during the Great War, it did not ignore the details or significance of the tank warfare that characterized the bulk of the conflict. After war’s conclusion, the Sultanate set about applying lessons learned elsewhere to the modernization of its armored forces, adapting them to Dalluhan demographic, geographic, economic, political, and cultural peculiarities, as well as prevailing geopolitical circumstances, military doctrine, and strategic planning.
Dalluha is tiny, mostly non-interventionist, very wealthy, and has a relatively small and highly educated population whose culture supports civil rights and the value of the individual. Many design features of the Direlba-51 directly reflect these circumstances, chief among which is a high value placed on crew protection.
General design and purpose
Dalluhan military planning assumed a near-exclusively defensive strategy, operating on its tiny home territory to defend against large numbers of massed infantry and armor. While such a role is often best suited to turretless tank destroyers and self-propelled guns - for example, Sweden’s Stridsvagn – the fact that the Direlba-51 was to be Dalluha’s only main battle tank, with an expected modicum of offensive capability for counter-attacks, meant that a turret was retained. For similar reasons, while defensive roles favor heavy tanks, such units are poorly suited to operating alone without lighter support, and some importance of mobility remained. The compromise was resolved by applying the armor thickness of a superheavy (IS-7, Maus) to a medium-sized body (T-44, Panzer IV), with the resulting 48-ton vehicle being comparably maneuverable to a heavier medium or lighter heavy tank (Panther or IS-2).
Development history
In anachronistic terms, the Direlba-51 can be thought of as a T-64 crossed with a Merkava. It was designed shortly after the War as the Dalluhan Army’s sole main battle tank, with an eye to straightforward conversion to other vehicle types, notably APC and IFV. The engine is located in the front, partly to provide additional protection for the crew - Dalluha would much rather lose machinery than people - and partly to open up the entire rear of the tank to a roomy fighting compartment with a rear ramp door. The turret is mounted somewhat aft of center, improving weight balance and thus its stability and accuracy as a firing platform, especially when moving.
The Direlba-51 was designed and built entirely in Dalluha by a consortium of private companies with government and military representatives, the dominant members of which were Dalluha Coach & Motor Works - a rising star in high-performance and luxury civilian cars - and Al-Qihas Shipyard - a well-established marine engine and hull manufacturer.
Early prototypes were powered by DCMW petrol V12 engines of 6-10l displacement, while the production tank was given its own, purpose-built 25-liter V12 turbocharged direct-injection diesel, relatively small for a 48-ton tank, but with 1200hp in normal service and up to 2000 in war emergency power, more than adequate for rapid maneuvering. The secret behind this unheard-of level of specific power is a monoblock engine design: with no separate cylinder head and crankcase, both whole cylinder banks are machined out of a single solid billet of forged steel. The extreme expense of such a manufacturing process was deemed a worthy price to pay for easier maintenance and significantly improved reliability. The engine design was for decades exalted as the epitome of DCMW’s engineering culture.
Chassis and running gear
The suspension is staggered leading/trailing arms with transverse torsion bars on the middle four pairs of rubber-rimmed road wheels, and pushrod-type coilover struts with hydraulic shock absorbers on the outermost four wheels. The result is compact, low to the ground, reliable, and offers a relatively smooth and steady ride. A 1958 revision further improved ride stability - important not just for comfort, but for fire accuracy - by the use of a hydropneumatic system. The front drive sprockets are powered via a double-differential transmission, allowing neutral steering, with hydraulically assisted manual shifting between eight gears and a forward/reverse transfer case.
Armor and protection systems
The armor itself is high-quality steel - welded cold-rolled plates forming the hull, while the turret is cast. Thickness varies from 25mm on the hull bottom, 130mm hull front, 80mm hull sides, and 50-280mm turret normal thickness. All surfaces are heavily sloped, improving protection even further than the nominal lne-of-sight thickness (up to 360mm on the front hull and front turret, excluding gun mantlet). Other combat equipment includes six turret-mounted smoke launchers, an active infra-red spotlight, two-axis gun stabilizer, positive-pressure interior ventilation with NBC-grade sealing, automatic fire extinguishers, and numerous redundant and easily-replaced vision blocks.
Armament
Intended primarily for defense against large waves of combined armor and infantry, the tank’s weapons were selected based on the importance of its likeliest targets: tanks first, infantry second, and fortifications a distant third. Though the main gun’s 85mm caliber is nothing special, even sub-par for the 1950s, its 75-caliber (6.4m) barrel length and superior build quality result in extremely high velocity, outstanding long-range accuracy, and excellent anti-armor capabilities, while the smaller caliber allows a high rate of fire, large ammunition capacity, and a small, compact turret.
Further space savings were realized by the use of an autoloader, increasing the rate of fire while reducing crew requirements to three, and the tank’s size as well. The turret is especially compact and narrow, reducing its chances of being detected, hit, or penetrated. The additional maintenance requirements of an autoloader were considered a small price to pay for a well-funded and well-educated army operating on its small home territory.
Secondary weapons are three machine guns - a heavy 14.5mm mounted to the powered commander’s cupola and able to be fired from inside, with hatches closed; one medium 7.62mm on a pedestal mount in front of the gunner’s hatch; and another 7.62mm mounted coaxially with the main gun. Furthermore, the spacious crew compartment easily fits rifles and other small arms for the crew or other personnel.
Operational history
A brief border skirmish broke out on December 25th 1966, the result of a series of drunken misunderstandings at an embassy christmas party, and general extreme confusion during the early years of the Chugunin regime. The Archanan 33rd mechanized infantry division, equipped with the latest rocket-armed IFV, and supported by the elite Red Guards 2nd heavy tank battalion, comprised primarily of TT-61 heavy tanks and a handful of TT-63 “Mammoth” siege tanks, crossed the border east of Krovavaja Gora and occupied several small towns in Dalluha’s Emerald Valley with only token resistance from the Dalluhan border guards. While the Basara Military District hastily prepared a counterattack, two platoons of Direlba-51 on a routine training exercise took the initiative and positioned themselves on the only road heading east from the valley.
The following day, the Archanan force attempting to break out of the valley was ambushed by the dug-in Direlba platoons. After two leading waves of mechanized infantry were totally routed, they brought in the tanks. To the astonishment of the invaders, the Direlba’s armor proved virtually immune to TT-61’s
formidable pair of 125mm main guns; even firing scarce and expensive tungsten-cored rounds, the Archanans only managed to disable two Direlbas by a hit directly on the main gun barrel, while another’s turret ring was jammed. Meanwhile, the Direlba’s extreme-velocity 85mm rounds had little trouble ventilating TT-61 hulls and turrets from well beyond the latter’s effective range.
The TT-63 was another matter; the Direlbas could not penetrate the Mammoths’ armor except at very close range, but at the same time, the Mammoths’ guns were too inaccurate to hit the low, compact Dalluhan tanks. One did score a lucky hit, causing the only Dalluhan armored casualty of the incident, but return fire disabled its tracks and it was abandoned during the retreat. The withdrawing remains of the Archanan force were pursued by the Dalluhan platoons, demonstrating excellent mobility even in deep snow, until the Dalluhans, already low on ammunition, also ran out of fuel. The Archanans went home, and the incident was concluded through diplomatic channels.
In the mid-1980s, the Archanan government bought most of Dalluha’s old stock of tanks, and assigned them to a training division that happened to be in Kronagrad when the army mutinied in January 1990. It was a pair of Direlba-51 that literally crashed the Party, demolishing the wall of the Supreme Council building while the Council was in session, ironically during a debate on historic building preservation.