JCh-8

JCh-8
The S.820N prototype and the first two service variants of the JCh-8.
Type	Main battle tank
Place of origin	Menghe
Service history
In service	2016-present
Used by	Menghe
Wars	Second Pan-Septentrion War
Production history
Designer	Chikai Tank Design Institute
Designed	2006-2016
Manufacturer	Chikai Heavy Machine Building Plant Insŏng Machine Building Plant Minchŏl Tank Factory
Unit cost	₩170 million ($7.56 million) (2016)
Produced	2016-present
No. built	11,262
Specifications (JCh-8G)
Weight	54 tonnes
Length	11.36 m (incl. fuel tanks)
length	7.47 m (excl. fuel tanks)
Width	3.76 m (incl. side armor)
Height	2.26 m (to turret roof)
Crew	3 (driver, gunner, commander)
Armor	welded steel base Composite armor (turret face and hull glacis)
Main armament	125mm L/56 smoothbore gun
Secondary armament	12.7mm GCh-75Ch HMG (commander) 7.5mm GCh-96 MMG (co-axial)
Engine	MT 883 Ka-500 1,500 hp
Power/weight	27.78 hp/tonne
Suspension	hydropneumatic in-arm suspension
Ground clearance	40 cm
Operational range	850 km
Speed	75 km/h (road)

The JCh-8 (formal designation: 8호 주력 전차 / 八號主力戰車, Pal-ho Juryŏk Jŏncha, "No.8 Main Battle Tank;" short designation: 전차-8, Jŏncha-pal) is a fourth-generation main battle tank developed in Menghe. Publicity announcements have also used the nicknames Jŏnsa, or "Warrior", and Usan, after the Battle of Usan Pass during the Five States and Seven Fiefdoms period.

Equipped with a hydropneumatic suspension, an active protection system, and provision for a 140mm main gun, the JCh-8 is considered one of the most advanced MBTs in Septentrion. It entered service with the Menghean Army in 2016, and was soon pushed into large-scale mass production at all three of Menghe's major tank factories. As of 1 April 2022, 10,562 JCh-8 main battle tanks of all variants had been delivered to buyers, making the JCh-8 the most common tank in the Menghean Army.

Development

Design requirements

In 2006, concerned over the new military standoff with Maverica and Innominada, the Menghean Ministry of National Defense issued a request for a new main battle tank. At this point, the JCh-6 had only been in service for two years, and there were no plans to end production; but combat experience during the Ummayan Civil War had revealed that the JCh-6's armor was insufficient to meet parity threats, and the Army was concerned that the already cramped vehicle left little room for major upgrades in the future.

Under the terms of the design competition, the new tank would need a slab-faced turret with thicker composite armor, a hydropneumatic suspension to improve stability on rough terrain, and a turret capable of mounting a 140mm gun in future upgrades. They also requested a high power-to-weight ratio, which led the designers to favor a gas turbine engine. At the time of its development, the new tank would be a world-class design, on par with the latest main battle tanks serving with the Entente Cordiale. As the Menghean designers soon learned, however, greater advances would also demand more expenses and a longer development time.

Competing prototypes

Early in the development process, Menghe's major tank design bureaus conducted a number of design studies on the most effective way to meet the MoND's requirements. These included Chikai's S.818, which put all three crew members in the hull; Insŏng's S.819, which put all three crew members in the turret; and Chikai's S.820, which had a more conventional layout with an angled turret ring. The most difficult part of the challenge for all entries was the need to store 140mm unitary ammunition in future upgrades. A 140mm unitary round would be long and cumbersome and could not be broken into two pieces, thus requiring either horizontal storage in a long turret bustle or vertical storage in a tall hull. Either arrangement would entail compromises in ammunition capacity.

The Chikai Heavy Machine Building Plant, producer of the JCh-5 and JCh-6, favored more conventional layouts, as the new tank would have to be produced on a large scale and remain reliable for decades to come. Chikai focused primiarily on the S.820, aiming to reduce the tank's vertical profile in comparison with the JCh-6 without investing in an unmanned turret or hull. This involved transferring all ammunition to the turret bustle, thereby removing the carousel ammunition stowage present on the JCh-6. Though ammunition capacity fell as a result, the first S.820 prototype nevertheless carried 34 rounds of ready ammunition, later reduced to 30 as Chikai adopted a slope-sided turret bustle.

Early in development, both Chikai and Insŏng favored gas turbine engines, believing that they would offer greater power in a more compact package and thereby allow the use of a smaller hull. Domestic efforts at land vehicle gas turbine development, however, fell short of expectations. By 2010, Chikai had selected the foreign MT 883 Ka-500 engine, which, despite being a diesel engine, offered greater power density than the Menghean gas turbine prototypes. Though horizontally shorter than the MB 873 used on the JCh-6, the MB 883 was slightly taller, adding to the hull's height at the rear. To compensate, Chikai sloped the entire roof of the hull at an angle of -4.1 degrees, shaving 13cm off the height at the center of the turret ring and 32cm off the height of the glacis plate.

Public unveiling

All development was conducted under a veil of near-total secrecy, with few individuals outside the design teams and the MoND's upper procurement ranks aware of the project's status. By the early 2010s, there were domestic and foreign rumors of a new Menghean MBT in development, but no photos had been released. When the Ministry of Defense published photos of the JCh-6D in May 2014, some foreign intelligence agencies erroneously identified it as the JCh-8. This judgment was not entirely inaccurate: Chikai transferred a great deal of experience from the S.820 prototype to the JCh-6D, including its slab-faced turret and fixed octagonal commander's cupola.

The first JCh-8 prototype did begin routine tests in the spring of 2014, but the first confirmed photos of the tank only became available in November of that year. Rumors that the new tank had been sent to the Menghean invasion of Innominada for front-line evaluation later proved to be false. Instead, the two existing hulls remained at a proving ground in Sanhu Province, undergoing continued tests.

After a steady stream of publicity photos and demonstration footage scattered through the preceding months, Menghe formally unveiled the JCh-8G service variant at the July 27th Victory Day Parade in Donggyŏng. Ten tanks equipped with the full defensive suite took part, leading the armored vehicles section of the parade under the banner of the 12th Tank Division. This provided the world with the first high-resolution footage of the JCh-8, and the first of any footage showing the addition of reactive armor and the Jŏgran-un system.

Design

Layout

At a glance, the JCh-8G bears a strong resemblance to the JCh-6D. It has a highly conventional layout, with the driver in the front of the hull, a manned turret centered behind him, and the engine compartment in the rear. There are six roadwheels and three return rollers per side, with the drive sprocket in the rear. Inside the turret, the gunner sits on the left and the commander sits on the right, a layout carried forward from the JCh-5, JCh-5.5, and JCh-6. The turret bustle contains an autoloader, eliminating the need for a fourth crew member.

On closer examination, however, the JCh-8G has a number of differences from the JCh-6. Most notably, the turret ring is not level with respect to the hull. Instead, it slopes slightly downward along with the hull's upper armor. This reduces the required height of the glacis plate, improves gun depression over the frontal arc, and eliminates a drawback of the JCh-6, namely, its inability to reload from the bustle autoloader while the gun is over the engine deck. The driver's position, which was centered on the JCh-5 and JCh-6, is offset to the left, a configuration last seen on the JCh-4. Internally, there is no carousel autoloader on the turret floor, with all ammunition stowed in the turret bustle.

These changes allow for a lower profile. At regular suspension height, with a ground clearance of 41cm, the JCh-8 is 14 centimeters shorter than the JCh-6G and 15 centimeters shorter than the JCh-6D. Adjusting the hydropneumatic suspension can lower its profile further. Accordingly, the JCh-8 has a somewhat reduced probability of being detected and hit, can concentrate its armor over a smaller frontal surface area, and can make better use of defensive terrain in a hull-down or turret-down position.

Protection

Until the end of the Second Pan-Septentrion War, little was publicly known about the JCh-8's armor scheme. The turret appeared to follow the same general construction as the turret of the JCh-6D, with a core hardened steel citadel and large modular composite armor blocks on the turret sides and turret face. This modular construction allows a tank unit to relatively easily replace heavily damaged armor modules in the field with the help of an armored recovery vehicle. The hull glacis plate is made up of two side-by-side composite modules, which are interchangeable between the left and right side. Menghean designers apparently considered this armor scheme sufficiently effective that they did not fit the JCh-6D or JCh-8G with reactive armor on the frontal arc, despite equipping all previous Menghean MBTs with some form of ERA on the turret face and glacis plate.

In addition to concentrating thicker armor on the tank's forward-facing surfaces, the designers of the JCh-8 relied heavily on steep armor sloping. The front half of the turret roof is sloped at 6 degrees below horizontal, and the roof of the hull is sloped at 4.1 degrees below horizontal. Both angles and thicknesses are sufficient to deflect long-rod APFSDS projectiles, even if they are descending at an angle of up to 2 degrees from horizontal.

During the early weeks of PSW2, the Maverican armed forces captured a large number of destroyed or disabled JCh-8 main battle tanks and were able to withdraw some of them for analysis. Measurement of the captured tanks confirmed that the turret frontal armor has a line-of-sight thickness of 980mm against a threat directly in front, while the turret side armor has a line-of-sight thickness of 360mm against a threat directly to the side. Adjusted for angling, the hull glacis is also roughly 980mm thick against a threat directly in front. The composite armor arrays are identical to the type used on the JCh-6D, consisting of stacked plates of hardened steel with air gaps in between. The turret bustle is protected by 80mm of hardened steel on the sides and rear, which provides protection against 30mm APFSDS at ranges of over 500 meters and can deflect high-caliber APFSDS projectiles at angles of less than 19 degrees off the gun's bearing.

Main armament

The main armament of the JCh-8G is the JChP-125 Type 11 125mm L/57 smoothbore gun. First introduced on the JCh-6D, this weapon is longer than the JChP-125 Type 01 used on late models of the JCh-5 and early models of the JCh-6, resulting in a higher muzzle velocity when firing high-power APFSDS ammunition. Rather than an extended 2A46, it is the product of an independent development effort, with an all-new breechblock and bore evacuator. The gun's trunnion is combined with a solid steel mantlet plate, providing better protection where the gun barrel meets the turret.

With the help of the sloped turret and sloped basket, the JCh-8 can reach a maximum gun depression of -8.7 degrees, a full 1.5 degrees more than the G and N models of the JCh-6 and 2 degrees more than the JCh-6D. When the suspension is "kneeling" at a maximum of -6 degrees, total gun depression over the forward arc comes out to -14.7 degrees. With the elimination of the carousel autoloader, the turret basket's floor is further below the breech, allowing for a maximum gun elevation of 20 degrees facing forward or 24.1 degrees relative to the angle of the turret basket. "Sitting" on the suspension adds a futher +6 degrees, and when the turret is traversed to the rear, the sloped hull roof adds 4.1 degrees, for a total elevation of 34.2 degrees. Compared to the elevation range of -6.7° to +15.9° on the JCh-6D and -7.19° to +14.55° on the JCh-6G/N, this wider elevation range allows the JCh-8 to fight more effectively in urban and mountainous areas, and to take up hull-down gun positions more effectively.

The bustle autoloader of the JCh-8 is modeled after the bustle autoloader of the JCh-6, with the ammunition carried in a sideways-0 shaped loop and moved around by metal paddles. The bustle autoloader is wider, increasing its capacity to 30 rounds over the JCh-6G/N's 14 and the JCh-6D's 18 rounds. The removal of the carousel autoloader, however, means that the JCh-8 carries fewer total rounds than the JCh-6G/N's 36 and the JCh-6D's 40.

Though the JCh-8 is capable of firing the YDCh-73 gun-launched ATGM, reports indicate that this weapon is rarely issued to Menghean Army units with the JCh-8. This may be an effort to maximize the number of stored conventional rounds, with non-line-of-sight ATGMs instead handed off to separate IFV or tank destroyer units.

Secondary armament

The secondary armament of the JCh-8, carried forward from the JCh-6D, is a GCh-96Ch general-purpose machine gun chambered in 7.5×54mm ammunition. This weapon is located on the upper right side of the gun breech and fires through a circular hole in the gun mantlet. Normally it is fired by the gunner by means of an electric solenoid trigger, but the commander can also fire the weapon manually in an emergency, or manually clear a jam. The electric trigger switch for the co-axial machine gun also activates an extractor fan which draws smoke away from its receiver and out a vent in the turret roof.

Ammunition is fed from a single belt with 6,000 rounds. Spent belt links are stored in one catch bin, and spent cartridge casings are stored in another; both bins are large enough for the gunner to exhaust all ammunition in the feed without having to dump casings out of a hatch in combat. Against the GCh-96Ch's 800-rpm rate of fire, the belt allows 7.5 minutes of continuous fire, though in practice this would be spread out over a large number of separate bursts.

Behind the commander's cupola, there is a 50mm-wide circular mount for a remote weapon system. On production-model JCh-8 tanks, this mount sports a combined remote weapon mount with a GCh-75Ch 12.7×108mm heavy machine gun and 200 rounds of ammunition, as well as an independent television and infrared optic for the commander's use and a dual visual/IR high-elevation optic for engaging aerial targets or infantry in tall buildings. The remote weapon system can elevate or depress through a range of -15° to +80° with the turret forward and the suspension level; as with the main gun, the bearing of the turret and the leaning of the suspension affect the weapon's actual elevation range on any given bearing. Four additional 200-round ammunition boxes are stored around the outside of the turret in enclosed bins. As a remotely-operated weapon slaved to the commander's optics, this weapon can fire on any bearing while the commander is safe inside the hull, but there are no manual backup controls which the commander can use to fire the weapon if its automatic controls are disabled.

Mobility

The JCh-8 is the first Menghean main battle tank to make use of an in-arm hydropneumatic suspension system in place of the more conventional torsion bars. All six road wheels have self-contained hydraulic arms connecting them to the lower sides of the hull. The driver can adjust the strength of the hydraulic dampening, optimizing mobility on different types of terrain. The adjustable suspension also allows the tank to tilt its hull forward and backward at the driver's command, "kneeling" to improve gun depression and "sitting" to improve gun elevation. When "lying down" with the hull floor on the ground, the tan's vertical profile falls to 1.86 meters. The JCh-8 can even lean side-to-side, or remain at a perfect vertical orientation on slightly sloped terrain.

The hydropneumatic suspension arms also eliminate the need for torsion bars running across the bottom of the tank's hull. This allows for internal components like the engine and the turret basket to be seated deeper in the hull, allowing for a lower hull profile than would otherwise be possible. Overall, the JCh-8 is slightly taller than the JCh-6R which preceded it, but it is lower to the ground than it would have been with a torsion bar suspension.

The tank's MT 883 Ka-500 powerpack combines a 12-cylinder transverse-mounted diesel engine and a ten-speed transmission with five forward and five reverse gears. The entire engine-transmission unit can be lifted out of the engine compartment with the help of a 6-ton crane, allowing relatively easy replacement in the field. The engine delivers an output of 1,100 kW or 1,500 hp, giving the tank a favorable power-to-weight ratio of 27.8 horsepower per ton. On a paved surface or hard, level ground, the tank can reach an artificially governed top speed of 75 km/h. Speeds of 82 km/h were reportedly achieved on trials with the armor kits removed, but at the cost of increasing the risk of damage to the tracks.

Other features

Internally, the JCh-8 features the same amenities as the JCh-6, including a relatively powerful air conditioning system to keep the crew compartment comfortable during in tropical weather and a water kettle to the right of the driver's seat. The removal of the carousel autoloader frees up additional space on the floor of the turret basket, including better storage space for the crew's defensive weapons. Combined with rubberized seals around the hatches and an air filter with an overpressure pump, these features allow the crew to eat, sleep, and fight from within the tank during prolonged maneuvers under CBRN-sealed restrictions.

Continuing a design tradition that started with the JCh-5, the JCh-8 is equipped with a retractable dozer blade on the lower front plate of the hull. By driving and reversing while the blade is lowered, the tank can dig an improvised hull-down firing position in soil or sand, fill in enemy anti-tank ditches, or demolish enemy fortifications or obstacles. Digging an improvised firing position usually takes 15-20 minutes, short enough for a tank unit to dig in relatively quickly ahead of an enemy counterattack. There are also mounting points for mine rollers and mine plows on the lower glacis plate, though these are not compatible with the mine rollers used by the JCh-6.

Variants

JCh-8G

This is the original production model of the JCh-8. It features spaced composite track skirts on the forward two-thirds of the hull and simple steel track skirts on the remaining third. Only the softkill components of the Jŏgran-un active protection system are fitted, despite the fact that the hardkill components were nearing production-ready status at that time. Thus, the tank's armor is supplemented by a laser and infrared dazzler light and laser and infrared blocking smokescreen projectors, both of which can be triggered automatically by passive missile approach warning sensors. As on previous Menghean main battle tanks, the missile approach warning sensors only cover the 180 degree frontal arc forward of the turret, leaving the tank vulnerable to attacks from the sides and rear. Production of the JCh-8G began in 2016.

JCh-8N

Beginning in 2019, all new-production JCh-8 tanks have been built as the JCh-8N variant. This variant features the full Jŏgran-un active protection suite, with phased-array radar panels on the turret corners and two pivoting hardkill countermeasure launchers with two projectiles each. Interestingly, while previous Menghean MBTs have only been fitted with two Jŏgran-un missile detection modules to cover the forward 180 degree arc only, the JCh-8 is fitted with four such modules, with two more on the turret rear. In combination with the pivoting hardkill countermeasure launchers, this grants the tank 360-degree protection against rockets and guided missiles.

140mm gun prototypes

One of the original design requirements for the JCh-8 was that it must be possible to refit the vehicle to carry a 140mm high-velocity smoothbore gun. For this purpose, the turret ring and the trunnion are both engineered to withstand the heavier weapon's recoil. Menghean sources also claim that it will be possible to remove the bustle autoloader and replace it with a bustle autoloader for a new unitary 140mm round. Little is known about Menghe's experimental 140mm unitary round, except that it is similar in length to the unitary 125mm round and somewhat wider at the base; therefore, a 140mm-gunned JCh-8 would not require a new turret bustle, but it would suffer a modest reduction in ammunition capacity.

As of April 2022, no production-model JCh-8 tanks carry the 140mm gun, which will instead be distributed as an upgrade if a better-protected Maverican or Entente tank enters service.

Production

When the JCh-8 first entered production, it was only manufactured at the Chikai Heavy Machine Building Plant, in a production hall set up exclusively for the new tank type. Production of the tested and proven JCh-6D continued in Chikai's other two existing production halls. The first batch of production-model JCh-8Gs was delivered to the 97th Kimsŏng Tank Division in late 2016, where they conducted extensive field exercises to assess the vehicle's performance and reliability.

After a little over a year of field evaluation, the General-Directorate for Procurement of the Menghean MoND ordered Chikai to convert its two other production lines to manufacture the JCh-8 and open a fourth production hall for the type. The Minchŏl Tank Factory converted its three production halls from the JCh-6D to the JCh-8G in 2018-2019, and the Insŏng Machine Building Plant made the switch in 2020. This gradual transition allowed time to implement minor design changes to improve reliability, and also smoothed out the demand for new tooling and reconstruction at Menghe's three major tank factories.

The transition from the JCh-8G to the JCh-8N was somewhat faster, with all tank factories producing the JCh-8N by 2021 after the first deliveries took place in 2019. The widespread scale of Menghe's adoption of the JCh-8N surprised some observers, who had initially expected that the full Jŏgran-un APS suite would be reserved for tanks in elite units; it may reflect a calculation that the increase in production costs from the addition of a hardkill active protection system is counterbalanced by the ability of those tanks to withstand a larger number of anti-tank guided missile attacks.

Official production figures state that by the start of the Second Pan-Septentrion War, Menghe had manufactured 7,284 JCh-8 tanks, about 60% of which were JCh-8N models. Total annual production of the type in 2021 surpassed 2,200 vehicles, roughly 35% higher than the peak level of JCh-6D production in 2016, reflecting the addition of two more production lines at the Chikai Heavy Machine Building Plant and the improvement of existing production lines and assembly halls. An official press release in 2016 cited a production cost of ₩170 million for each JCh-8G, equivalent to $7.56 million in 2016 international Septentrion dollars; the Jŏgran-un suite of the JCh-8N adds an estimated $200,000 to per-unit production costs, but independent estimates suggest that the scale of JCh-8 production has also realized some economies of scale since 2016, such that actual unit costs may remain below $8 million at current (2022) prices.

Service

Upon the outbreak of the Second Pan-Septentrion War on 11 April 2022, the JCh-8 was the most numerous main battle tank in the Menghean Army's inventory, with over 11,000 units delivered to front-line units. Active divisions in the Army Group of Forces in Innominada and the Army Group of Forces in Menghe had received priority in deliveries, though even Kimsŏng divisions in the Dzhungestani theatre primarily used later models of the JCh-6. Up to 2022, Menghe did not export the JCh-8 to any foreign countries, even members of the Namhae Front, instead prioritizing deliveries to the Menghean Army.

Crews liked the JCh-8 for its smooth offroad ride, its low silhouette, and its wider range of gun elevation and depression, as well as the basic amenities which it carried forward from the JCh-6. Major complaints included concerns about the reliability of the hydropneumatic suspension system, which, in the findings of one report, stemmed primarily from crew members' lack of experience maintaining the new system.

During the four weeks of fighting that characterized the Second Pan-Septentrion War, the JCh-8 earned a proven reputation as an effective combat vehicle. Its low profile and adjustable suspension made it particularly effective in improvised defensive positions, and its state-of-the-art fire-control system and stabilizer provided excellent accuracy when firing from a stationary position or on the move. Consistent with tests conducted during the design process, the JCh-8 was able to withstand 125mm two-piece ammunition at all combat ranges over the frontal arc, though Maverica's unitary 125mm APFSDS ammunition performed better than expected against its frontal armor. In particularly intense engagements, such as the Maverican offensive against the 7th Army in the opening days of the war, the JCh-8's limited magazine capacity forced crews to withdraw or surrender after exhausting their main gun ammunition; some reports indicate that this impacted morale in crews using the JCh-8. As the balance of Menghean and Maverican forces stabilized and the intensity of the fighting declined, however, JCh-8 units were generally able to maintain adequate ammunition loads.

See also

• Werewolf (tank)