View source for M V/M VII Opsiános

{{Infobox weapon|name=M6/M7 Opsiános|type=[[Main Battle Tank]]|is_vehicle=yes
<!-- Service history -->|service=1948 - present|wars=See ''[[#Operational History|Operational History]]''|image={{border|[[File:M6B.png|300px]]|1}}|caption=An Opsiános ''Beta'' of the 2nd Independent Tank Cohort, early 1950s|used_by={{unbulleted list 
|{{flagicon|Sofíae Commonwealth}} [[Sofíae Commonwealth]]
|{{flagicon|Nurmandria}} [[Nurmandria]]
|{{flagicon|Chzeknye}} [[Chzeknye]]
}}|unit_cost={{bulleted list 
|M8 - 310.000≸ (1970) [=12.700.000≸ (2020)]
}}|weight={{bulleted list 
|M8A - 44.5 t
|M8E - 47 t
}}|engine_power={{bulleted list 
|M8A - 850 hp
|M8E -  1000 hp
}}|length={{bulleted list 
|M8E - 6,82m (hull)
}}|engine={{bulleted list 
|M8A/B/C/D - 4K4 8 cylinder diesel
|M8 - 4K4-V 8 cylinder diesel
}}|pw_ratio={{bulleted list 
|M8 - 19,10 hp/t
|M8 - 21,28 hp/t 
}}}}

The '''M6''' '''Opsiános''' and '''M7''' '''Soúper Opsiános''' (M6/M7 Οψιδιανός/Σούπερ Οψιδιανός) tanks are a series of [[Sofíae Commonwealth|Sofíae]] main battle tanks introduced in the years following the Great War. The first M6 prototype was completed at Arlansor by the end of 1946. From the late 1950s, the M6 eventually became the main tank for armoured units of the Sofíae Commonwealth Army, armies of the Warsaw Pact countries, and many others. M6s and M7s have been involved in many of the world's armed conflicts since their introduction in the second half of the 20th century.

The M6/M7 series is the most-produced tank in history. Estimated production numbers for the series range from 96,500 to 100,000. They were replaced by the M8, M8/7, and M9 tanks in the Sofíae Army, but remain in use by up to 50 other armies worldwide, some having received sophisticated retrofitting. The Seojian version of the M6C is the Type 59.

During the Cold War, Sofíae tanks never directly faced their NATO adversaries in combat in Europe. However, the M6/M7's first appearance in the West around the period of the 1950s (then the beginning of the Cold War) spurred the United Kingdom to develop a new tank gun, the Royal Ordnance L7, and the United States to develop the M60 tank.

==Development history==
===Predecessor: M4===
{{Main|M4}}

In 1943, the [[Tenediktos-Kostas Skormovo Design Bureau]] (TKSDB) created the first prototype of the [[T-44 tank|M4 tank]], the M4 had cross country performance at least as good as the M2, but with substantially superior [[Vehicle armour|armour]] and a much more powerful 80 mm gun.

By 1944, the M2 had also been modified to fit the same gun. Although the M4 was superior in most other ways, it was felt that a bigger advantage over the M2 would be needed to justify switching production to a new model. The designers thus tested further improved guns, experimenting with a 100 mm design, but later decided that an even longer 80 mm gun was a better alternative.

===Prototypes ===
Efforts to fit the 100 mm gun to the M4 demonstrated that small changes to the design would greatly improve the combination. The main issue was a larger turret ring, which suggested slightly enlarging the hull. A prototype of the new design, about {{convert|70|cm}} longer and only 10 cm wider, was completed in 1945. This model looked almost identical to the original M4, albeit with a much larger gun.

Testing revealed several drawbacks that needed correcting and many alterations that had to be made to the vehicle's design. By 1947 TKSDB had produced a new prototypes incorporating several changes, chief among them were a novel transverse engine mount and pneumatic tires which helped to reduce weight and reduced the tank's overall lenght. It was decided to begin serial production of the new vehicle and it officially entered service in April 1947. It would go into production in [[Uralvagonzavod|Arlansor]] in 1948 and [[Malyshev Factory|Skormovo]] in 1949.

===M6 Opsiános A ===
[[File:M6A.png|thumb|Opsiános A-I at an unknown tank firing range, 1951]]
Production of the initial series of M6s began slowly as 1,490 modifications were made. The Sofíae Army received a tank that was superior to World War II designs and theoretically better than the newest tanks of potential opponents. The 100 mm gun fired BR-412 series full-calibre APHE ammunition, which had superior penetration ability when compared to the M4 that it replaced.

The serial production version, designated Opsiános A (or A-Ⅰretroactively), differed from the second M6 prototype. It had thicker hull armour (80 mm on the sides, 30 mm on the roof and 20 mm on the bottom).<sup>[''citation needed'']</sup> As production ramped up, quality problems emerged. Production was stopped and an improved A-Ⅱ(''Proiókt'' 137R) version was designed. Several changes were made and a new turret was fitted. The new dome-shaped turret with flat front sides was inspired by the turret from the G4 heavy tank.

The fender machine guns were removed in favour of a single bow-mounted machine gun. The transmission was modernised and new TSh-2-22 telescopic gunner's sight replaced the older TSh-20 model. The tank featured the TDA smoke generating system and the track was widened to 580 mm. The Opsiános A-II entered production in 1950, at Ulrech Svarald Tank Factory No. 183 (now [[Arlansor Armored-Vehicle Plant (ASVE)|ASVE]]). A command version was built, the M6A-ⅡI (''igesía''), with a second R-113 radio.

=== M6 Opsiános B and C===
In the beginning of the 1950s, the design team at GSP-60 ([[Tenediktos-Kostas Skormovo Design Bureau|TKSDB]]) decided to fit the 100 mm D-10T tank gun with the STP-1 "Gorizont" vertical stabilizer. The new tank gun received the designation D-10TG and was fitted into the M6's turret.

The new tank received night vision equipment for the driver and was designated Opsiános B (''Proiókt'' 137G). It was equipped with an OPVT wading snorkel, the TSh-2A-22 telescopic sight, TVN-1 infrared driver's periscope and IR headlight, a new R-113 radio, multi-stage engine air filter and radiator controls for improved engine performance, an electrical oil pump, a bilge pump, an automatic fire extinguisher and extra fuel tanks.

The tank officially entered production in 1955 and service in 1956. It served as a basis for M6BI command tank, with additional R-112 radio set (front line tanks were equipped with R-113 radio set), TNA-2 navigational device, ammunition load for the main gun decreased by 5 rounds and the AB-1-P/30 charging unit, which was produced in small numbers. <s>In October 1955 a M6B tank, designated as M6V (''Proiókt'' 139) served as a testbed for new D-54T and D-54TS 100 mm smoothbore guns and "Raduga" and "Molniya" stabilization systems, which were later used in the T-62</s> (see if we can incorporate some M5 refs in this). These were not completely successful, so further M7 development continued to use the D-10 series guns. It was fitted with V-54-6 engine developing 581 hp (433 kW). It never went into production.

A new version, based on the Opsiános B, designated Opsiános C (''Proiókt'' 137G2), was designed in 1955. It was fitted with a new 100 mm D-10T2S tank gun with STP-2 "Tsyklon" 2-plane stabilizer. It entered production in 1958. During the last four months of production, the new tanks were equipped with an L-2 "Luna" infrared searchlight, a TPN-1-22-11 IR gunner's sight, and an OU-3 IR commander's searchlight. Modern APFSDS ammunition was developed, dramatically enhancing the penetrative performance of the gun to keep it competitive with NATO armour developments. The Opsiános C served as the basis for the "CI" command tank, which had exactly the same additional equipment as the "BI" command tank.

===M7 Soúper Opsiános ===
Trials with nuclear weapons showed that a M6 could survive a 2–15 kt nuclear charge at a range of more than 300 metres (980 ft) from the epicentre, but the crew had a chance of surviving at a minimum of 700 metres (2,300 ft). It was decided to create an NBC (nuclear, biological, and chemical) protection system which would start working 0.3 seconds after detecting gamma radiation.

The task of creating a basic PAZ (''Protivoatomnaya Zashchita'') NBC protection system offering protection against the blast of a nuclear weapon and (radioactive) particulate filtration, but not against external gamma radiation or gas, was given to the KB-60 design bureau in Kharkiv and was completed in 1956. The documentation was sent to Uralvagonzavod. It was decided to increase the tank's abilities by changing its construction and introducing new production technologies. Many of those changes were initially tested on the M6M (''Proiókt'' 139).

The tank was fitted with the new V-55 12-cylinder four-stroke one-chamber, 38.88-litre water-cooled diesel engine developing 581 hp (433 kW). Engine power was increased by raising the pressure of the fuel delivery and charging degree. The designers planned to introduce a heating system for the engine compartment and MC-1 diesel fuel filter. The engine was to be started pneumatically with the use of an AK-150S charger and an electric starter. This eliminated the need for the tank to carry a tank filled with air. To allow easier access during maintenance and repairs, it was decided to change hatches over the engine compartment. To increase the operational range, 300 litres (66 imp gal; 79 US gal) fuel tanks were added to the front of the hull, increasing the overall fuel capacity to 680 litres (150 imp gal; 180 US gal).

The ammunition load for the main gun was increased from 34 to 45, with 18 shells stored in so-called "wet containers" located in hull fuel tanks (the concept for which came from Kartsev's cancelled ''Proiókt'' 140). The ammunition load included high explosive-fragmentation and anti-tank rounds and designers also planned to introduce the BK5M high-explosive anti-tank (HEAT) rounds which penetrated 390 millimetres (15 in) thick armour. The TPKU commander's vision device was replaced by either the TPKUB or TPKU-2B. The gunner received a TNP-165 vision device.

The loader's hatch-mounted 12.7 mm DShK anti-aircraft heavy machine gun was dropped, because it was deemed worthless against high-performance jets. The tank was supposed to be equipped with the "Rosa" fire protection system. The tank had a thicker turret casting and the improved two-plane gun stabilization system from the M6B, and night vision fighting equipment. To balance the weight of the new equipment, the armour on the back of the hull was thinned slightly.

The M7 was superior to the IS-2, IS-3 and T-10 heavy tanks in many respects, including the rate of fire of the gun (at least four compared to fewer than three rounds per minute). Despite somewhat thinner frontal turret armour (200 millimetres (7.9 in) instead of 250 millimetres (9.8 in)) it compared favourably with the IS-3, due to its improved antitank gun and better mobility. Heavy tanks soon fell from favour.

The old model of highly mobile medium tanks and heavily armoured heavy tanks was replaced by a new paradigm: the "main battle tank". Parallel developments in the West would produce similar results. Kartsev combined all the ongoing improvements being offered, or planned, on the M6 into one design. This became the ''Proiókt'' 155, and entered production at Uralvagonzavod 1 January 1958 as the M7. It was accepted for service with the Red Army on 8 May. It suffered a significant lapse in one area: there was no antiaircraft machine gun, which had been present on the M6.

After 1959, it served as a basis for the M7K command tank which was equipped with an additional R-112 radio set, an AB-1-P/30 fuel powered accumulator charging unit, and TPN-1-22-11 night vision sight. All this additional equipment made it necessary to decrease the ammunition load for the main gun to 37 rounds and eliminate the bow machine gun. In the beginning of the 1960s, a M7K was experimentally fitted with a ''Uran'' TV relay apparatus for battlefield surveillance. The tank was fitted with an external camera, the picture from which was relayed to a receiver in a BTR-50PU command vehicle. There was an observation camera mounted on a folding mast which was in turn mounted on a UAZ 69 car.

In 1961, a M7 tank was used to test the "Almaz" TV complex, which was supposed to replace the standard observation devices right after a nuclear explosion or while fording a body of water. There was a camera mounted on the hull for the driver and two cameras mounted on the turret, one for aiming and one for observation, and the picture from the cameras was relayed to two control screens. The tank had the front hull fuel tanks and bow machine gun removed. The commander was seated in the driver's usual position while the driver sat next to him.

The cameras allowed battlefield observation and firing during daytime at ranges between 1.5 and 2 kilometres (0.93 and 1.24 mi). Because of the low quality of the equipment, the trials gave negative results. In the beginning of the 1960s, the OKB-29 design bureau in Omsk was working on adapting the tank to use a GTD-3T gas turbine engine developing 700 hp (522 kW). One M7 tank fitted with this gas turbine engine passed trials but was deemed unsatisfactory and the design did not go into production.

The Omsk OKB-29 group tested three experimental M7 tanks (designated ''Proiókt'' 612) between 1962 and 1965 that were fitted with an automatic gearbox controlled by electro-hydraulic systems. The trials found that such gearboxes were prone to frequent breakdowns in tanks. At the same time the ''Proiókt'' 155ML, a M7 fitted with a launcher for three 9M14 "''Malyutka''" (NATO code: AT-3 Sagger) ATGMs mounted on the rear of the turret, was tested. Along with standard tanks a flamethrower-armed version was designed (designated TO-55 (''Proiókt'' 482)), which was produced until 1962. It was fitted with 460-litre tanks filled with flammable liquid instead of the frontal hull fuel tanks. The flamethrower replaced the coaxial machine gun. This was a much better way to mount a flamethrower than in the experimental ''Proiókt'' 483, based on the M6 tank, where the flamethrower replaced the main gun. TO-55 flamethrower tanks were withdrawn from service in 1993.

=== M7A===
In 1961, development of improved NBC protection systems began. The goal was to protect the crew from fast neutrons; adequate protection against gamma radiation was provided by the thick armour and a PAZ basic NBC protection system.

The POV plasticized lead antiradiation lining was developed to provide the needed protection. It was installed in the interior, requiring the driver's hatch and the coamings over the turret hatches to be noticeably enlarged. This liner had the added benefit of protecting the crew from fragments of penetrated armour.

The tank was equipped with a full PAZ/FVU chemical filtration system. The coaxial 7.62 mm SGMT machine gun was replaced by a 7.62 mm PKT machine gun. The hull was lengthened from 6.04 m to 6.2 m. The hull machine gun was removed, making space for six more main gun rounds. These changes increased the weight of the vehicle to 38 tonnes.

The design work was done by OKB-520 design bureau of Uralvagonzavod under the leadership of Leonid N. Kartsev. The M7A served as the basis for the M7AK command tank.

=== M6/M7 upgrades===
In its long service life, the M7 has been upgraded many times. Early M7s were fitted with a new TSh-2B-32P sight. In 1959, some tanks received mountings for the PM7 mine clearing system or the BTU/BTU-55 plough. In 1967, the improved 3BM-8 APDS round, which could penetrate 275 mm thick armour at a range of 2 km, was introduced. In 1970, new and old M7 tanks had the loader's hatch modified to mount the 12.7 mm DShK machine gun, to deal with the threat of attack helicopters. Starting in 1974, M7 tanks received the KTD-1 or KTD-2 laser rangefinder in an armoured box over the mantlet of the main gun, and the R-123 or R-123M radio set. Simultaneously, efforts were made to modernize and increase the lifespan of the drive train.

During production, the M7A was frequently modernised. In 1965, a new track was introduced that could be used for between 2,000 km and 3,000 km, which was twice the range of the old track. It needed a new drive sprocket, with 14 teeth instead of 13. Since 1974, M7A tanks were equipped with a KTD-1 "Newa" rangefinder and a TSzS-32PM sight. All M7A tanks were equipped with the TPN-1-22-11 night sight. The R-113 radio set was replaced by a R-123 radio set. Late production models had rubber side skirts and a driver's windshield for use during longer stints.

M6 and M7 tanks continued to be upgraded, refitted, and modernised into the 1990s. Advances in armour-piercing and high-explosive anti-tank (HEAT) shaped charge ammunition would improve the gun's antitank abilities in the 1960s and 1980s.

A wide array of upgrades in different price ranges are provided by many manufacturers in different countries, intended to bring the M6/55 up to the abilities of newer MBTs, at a lower cost. Upgrades include new engines, explosive reactive armour, new main armament such as 120 mm or 125 mm guns, active protection systems, and fire control systems with range-finders or thermal sights. These improvements make it a potent main battle tank (MBT) for the low-end budget, even to this day.

One of these upgrade packages was a joint United States-China prototype designed and built by Cadillac Gage, now known as Textron. Two prototypes based on the Chinese Type 59 tank, a clone of the Soviet Union era M7, named Jaguar were produced in Detroit, Michigan.  Modifications included a new turret design and improved hull.  The engine compartment and fuel tanks on the shelves over the tracks were armour-protected. The Soviet-made 100 mm gun was replaced with the American M68 105 mm rifled gun fitted with a thermal sleeve. A Marconi fire control system which was originally developed for the American light tank Stingray was fitted. The vehicle incorporated a Cadillac Gage weapon stabilizer and gunner's sight equipped with an integral laser rangefinder. The powertrain was replaced with a Detroit Diesel 8V-92TA engine and XTG-411 automatic transmission. In 1989, two prototypes were completed. The chassis were provided by PRC, while the hull tops, turrets and powerplants were manufactured by Cadillac Gage Textron. Field testing of the prototypes began in October 1989, four-months after the 1989 Tiananmen Square protests and massacre, which ended cooperation between China and Cadillac Gage.

Another prototype upgrade package was produced by Teledyne Continental Motors (now General Dynamics Land Systems) for the Egyptian Army and was known as the M6E. After further modifications and trials it was sent into mass production and received the designation Ramses II.

As late as 2013, Ukrainian companies were reportedly developing M7 main battle tank upgrades targeting the export market. The Type 59 is still in production, in several variants.

==Production History==
The initial production date for the ''Granítis'' is between late 1964 and early 1965 and it formally entered service with the Sofíae Army in 1967, being publicly revealed in 1970. The M8 was KSE's high-technology offering, intended to initially replace the G5 heavy tanks in independent tank battalions, while improved M6 models would still equip the bulk of the Commonwealth's tank and mechanized forces at least until the late 1970s.

It introduced a new autoloader, which is still used on all ''Granítis'' variants currently in service. The M8 prototypes had the same 100mm or 130 mm rifled guns as the M6 and G5, the ones put in full-scale production had the 120 mm smoothbore gun.

production ends in 1987

===Models===
[[File:G9earlyphoto.png|thumb|A M9B with its ''Akakía'' ERA side panels removed, unknown region, 1998]]
In common OFSN nomenclature the five main variants are referred to as "''A'', ''B,'' ''C, D'' and ''E''", although the proper traslitteration from Valárian would be "''A'', ''B'', ''G, D'' and ''E''" as in "''Alfa,'' ''Beta,'' ''Gamma, Delta'' and ''Epsilon''". Command tanks with more radio equipment have ''I'' added to their designation for ''igesía'' (''ηγεσία'', meaning "command"), for example, ''Granítis CI'' is the command version of the Granítis C. Versions with added armor compared to the base model (either ERA or other) have an ''S'' suffix, for ''scutate'' (''σκυτατε'', meaning "(up)armored"), for example ''Granítis BS''. Upgraded tanks receive the ''V'' designation for ''veltioméni'' (''βελτιωμένη'', meaning "improved").

*'''Proiókt 295''': 10 prototype vehicles produced from 1961 to 1965. the first three vehicles built served as production and layout test-beds and had the same 6-6K-3V V12 engine used on the M6; from the fourth vehicle the aluminium alloy and silica inserts where incorporated on the hull front plate and turret cheeks (Proiókt 295.1); the last four vehicles built introduced the 4K4 8-cylinder opposed-piston engine (Proiókt 295.2), developing 850 hp this gave the roughly 44 tons tanks a power to weight ratio of almost 20 hp/t. All the prototypes were armed with an improved 59(V)-ΟΜ100 100mm gun which would later be fitted to the M6C; this gun used one piece ammo stored in the hull front and in the turret's bustle and was manually loaded by a dedicated loader.
*'''Proiókt 296''': 6 prototypes produced in 1964 and 1965 with 130mm 48(F)-ΟΜ130 (lightened version of 48-ΟΜ130 used on the G5, with added muzzle brake), uses two piece ammo stored in innovative basket autoloader. The gun proved too heavy for the stabilizer to work effectively, and only carried 25 round.

*'''Granítis A''': first production model, adopted in 1967, uses the new 50-ΟΜ120 gun which is fed by the R1120 autoloader derived from the Proiókt 296 holding 28 rounds. This system proved to be extremely fragile in service, with tank crews reporting up to one malfunction every three rounds loaded, especially if the vehicle was moving over rough terrain or at high speed during the autoloading operation. The development of an improved autoloader had already started even before the tank's formal adoption and production switched to this new version in 1969. Most Granítis A were brought to the "B" standard by replacing the autoloding system between 1969 and 1973.
**'''AS''': in 1972, 70 vehicles were fitted with armored side-skirts of high resistance steel 8 mm thick and additional glacis armour of the same high resistance steel with a thickness of 20 mm.
**'''AI''': (1969) Command version, with an Exéntypo O-100 radio with a dedicated antenna, a SPG-3 navigation system, without antiaircraft machine gun, carrying 25 shells.

*'''Granítis B''': Tanks produced from September 1969, equipped with the more robust R1121 autoloader; this vehicles were originally designated Granítis AV, but this was later changed to Granítis B in 1972; other than the improved autoloader, this vehicles had other smaller improvements, like extended storage bins on the sides of the turret; starting in 1971 an entrenching blade was fitted to most tanks from the factory.
**'''BS''': from 1972 to 1976, over 1000 Granítis B received the up-armoring trialed on the "AS" tanks, this was intended to keep their protection close to the one offered by the Granítis C and D.
**'''BI''': all Granítis AI were brought to the BI standard in 1970-1971 by replacing the autoloding system.
**'''BSV''': 2006 modernization for Nurmandian "BS" tanks, thermals only go on nurmy upgrade (also even better engine, akakia ERA and enlarged basket)

*'''Granítis C''': improved composite formula, changed smoke granades, new radiator
**'''CX''': ("X" for ''xeno'' – foreign)
**'''CV''': composite screens, ''Dorea'' ERA, the lot

*'''Granítis D''':  changed hull construction,  laser rangefinder, LLLTV in box, blow out panels, added ability to fire gun-launched ATGMs
**'''DV''': composite screens, ''Dorea'' ERA, the lot
**'''DI''': (1976) Command version, with an Exéntypo O-130M radio and its 10-m telescoping antenna, a SPG-3 navigation system and EE-50/10 APU, without antiaircraft machine gun, retains 28 rounds of main gun ammunition. Some "DI" tanks were fitted with ''Exousía'' APS sets some time during the early 1990s.
*'''Granítis E''': improved stabilizer and optics, era 1 and laser rf from start, new ir light, uprated engine

==Service History==

==Operators==
===Current Operators===

*{{flagicon|Sofíae Commonwealth}} '''[[Sofíae Commonwealth|CSCR]]'''
*{{flagicon|Nurmandria}} '''[[Nurmandria]]'''
*{{Flagicon|Tihama}}'''[[Tihama]]'''
*{{Flagicon|Chzeknye}}'''[[Chzeknye]]'''

===Former operators===

*{{Flagicon|Secrazchak}}'''[[Secrazchak]]''': Passed on to successor states (including Chzeknye).
**{{Flagicon|Goriyar}}'''[[Goriyar]]'''
**{{Flagicon|Kirkassag}}'''[[Kirkassag]]'''
**{{Flagicon|Moten-Nizar}}'''[[Moten-Nizar]]'''

[[Category:Realstrange]]
[[Category:Vehicles of Realstrange]]
[[Category:Sofíae Commonwealth]]

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