JCh-8

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. 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.

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 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.

See also

• JCh-6
• JCh-7
• BSCh-9