JCh-4

JCh-4
Main variants of the JCh-4 with the year they entered service.
Type	Medium tank
Place of origin	Menghe
Service history
In service	1977-present
Used by	Azbekistan Dzhungestan Menghe Qusayn Ummayah Uskonmaa
Production history
Designed	1972-1976
Manufacturer	Minchŏl Tank Factory Chikai Heavy Machine Building Plant Insŏng Machine Building Plant
Produced	1976-1995
No. built	10,275
Specifications
Weight	39.2 metric tonnes
Length	10.68 m (inc. gun and fuel drums)
Width	3.35 m
Height	2.44 m to turret roof
Crew	4 (driver, gunner, commander, loader)
Armor	welded steel plate Turret face: 280mm Glacis plate: 120mm at 70 degrees
Main armament	107mm JP-107/56
Secondary armament	12.7mm GCh-75Ch HMG (commander’s cupola) 7.62mm GCh-77Ch machine-gun (co-axial)
Engine	12-cylinder diesel 800 hp
Power/weight	20.9 hp/tonne
Suspension	torsion bar
Ground clearance	45 cm
Operational range	500 km
Speed	60 km/h (road)

The JCh-4 (Formal designation: 4호 중형 전차 / 四號中型戰車, Sal-ho junghyŏng jŏncha, "No.4 Medium Tank;" short designation 전차-4, Jŏncha-sal) is a type of medium tank designed in the Democratic People's Republic of Menghe during the 1970s. It is based on the JCh-2, but incorporates a number of major changes, including a 107mm smoothbore gun, a longer hull, and thicker armor on the turret and glacis plate. These changes were sufficiently major that the vehicle was designated a new tank altogether, rather than a JCh-2 variant.

Development

Even in the early 1970s, the Menghean People's Army began to express concern that its JCh-2 tank was growing obsolete. It pressured Letnia for permission to import or domestically manufacture the T-66, which would later become the JCh-5, but until 1975 the Letnian government refused to lift export restrictions on the new tank. Even after that point, the Army leadership remained concerned that the JCh-5 was too expensive and unreliable to serve all units, and instead called for a major upgrade to the JCh-2.

The resulting prototype incorporated a number of features not seen on its Letnian cousins. It had a new gun, turret, and hull, and brought a major increase in capability, though it remained behind the global standard for the time. As a result of these extensive modifications, the new vehicle and its successors were classified as a new tank family altogether, rather than variants of the JCh-2.

Description

The most fundamental difference between the JCh-2 and JCh-4 is the latter's hull, which was stretched to accommodate thicker frontal plating, a heavier turret, more ammunition stowage, and a more powerful engine. Altogether, the JCh-4's hull is 36 centimeters longer than that of its predecessor. This resulted in considerably greater spacing between the 3rd, 4th, and 5th roadwheels, the main feature allowing an observer to tell the tanks apart from a distance. Other distinguishing features include a rounder turret with a more bulged face, a bore evacuator closer to the turret than the muzzle, and external fuel drums mounted somewhat lower down than on the JCh-2.

Armament

The JCh-4's main armament is a JP-107/56 107mm smoothbore gun with a heavier thermal sleeve, a change intended to improve armor penetration and barrel life. As a smoothbore weapon, it is optimized for firing APFSDS ammunition, though APFSDS cartridges with rifled slip rings later became available for the JCh-2. The gun is equipped with both vertical and horizontal stabilizers. As on the JCh-2, the gun is manually loaded, with the gunner sitting on the right side of the breech and the gunner and commander on the left. This forces the loader to ram main gun rounds into the breech with his left hand, but allows him to use his right hand to move the round's nose into position. Though it drew some criticism from foreign evaluators, the left-handed ramming arrangement was not found to have a significant impact on the tank's rate of fire, especially as Menghean tank loaders of the time were also trained for the left-hand-loading JCh-1, JCh-2, and JCh-3.

On "G" models and their derivatives, the co-axial machine gun is an unlicensed copy of the AA-52 machine gun, though on the JCh-4N onward it is a GCh-77. In both cases, the weapon is chambered in 7.5×54mm Sieuxerrian and 2,500 rounds are carried in 250-round boxes which the loader must manually replace as they are individually exhausted.

All JCh-4 models are equipped with a GCh-75 anti-aircraft heavy machine gun. While the JCh-2's roof HMG is operated by the loader, on the JCh-4 this weapon is fitted to the commander's cupola, and was included from the start of the design process rather than being added in refits. On the JCh-4G, the commander's cupola is asymmetric, with the main forward-facing periscope offset to the left and a pintle mount for the anti-aircraft machine gun offset to the right. The HMG does rotate along with the commander's cupola, which can be rotated from inside the vehicle, leading to widespread but incorrect reports that the commander of the JCh-4 can fire the HMG from under armor. In reality, the HMG only rotates because its mounting point is attached to the cupola, and there is no way to elevate, fire, or precisely train the weapon from within the vehicle. The "G" model HMG mount also made the commander's cupola front-heavy (or more specifically, front-right-heavy), making it difficult to turn, especially when the tank is on sloped ground. New-build variants from the JCh-4N onward switched to a different HMG mounting system.

Protection

In addition to carrying a more powerful main armament, the JCh-4 was also better-protected. Its hull glacis plate is 20 millimeters thicker and set at a steeper angle, while its turret incorporates thicker armor on the frontal arc, and has a less noticeable slope on the roof. Side, rear, and floor armor are identical in thickness to armor at the same locations on the JCh-2. Despite these improvements, the JCh-4 remained a poorly armored tank in all of its variants, and could easily be penetrated by contemporary main battle tanks at regular combat ranges.

From the first "G" variant onward, the JCh-4 also incorporated a CBRN protection system consisting of airtight hatches and air filters, allowing the tank to operate in contaminated areas. The overpressure system on early tanks, however, was relatively weak, and the spent cartridge ejection hatch could compromise the seal when opened. Therefore, it became common for crews to operate the vehicle while wearing protective gear if there was a threat of chemical weapons use.

Mobility

To compensate for its heavier armor, the JCh-4 was fitted with a more powerful 800-horsepower engine, giving it a power-to-weight ratio of 20.9 hp/tonne. On level roads, it could achieve top speeds of 60 kilometers per hour, at which point it was limited mainly by the vibration of the tracks, which lacked return rollers.

The large engine was considerably thirstier, but the JCh-4 compensated for this by adding additional fuel tanks along the outside of the hull, on top of the track covers. This extended operational range to 500 kilometers, or 650 with external fuel drums attached.

As manufactured, all major JCh-4 variants lack the snorkeling equipment ubiquitous on later Menghean tanks. This reflected a belief at the time of their design that Menghe would most likely fight any near-future wars on the defensive or on the steppes of Central Hemithea, making the rapid crossing of unprepared water obstacles unnecessary. Many exported JCh-4s were, however, refitted with snorkeling equipment as part of the export deal, and during the late 2000s Menghe applied the same refits to many of its JCh-4s still in service.

Original variants

JCh-4G

The designation JCh-4G was given to the first series-production model of the JCh-4. It can be identified by the design of the commander's cupola, with a forward-facing 12.7mm HMG that rotates along with the cupola. Other differences include the rotating loader's hatch with a single periscope and the radio antenna on the rear of the turret. Less visible differences include the use of an unlicensed AA-52 coaxial machine gun and turret handrails that run all the way to the sides of the turret. As originally built, the JCh-4G had no side skirts, smoke grenade launchers, or applique armor of any kind, though these were later added to many vehicles in refits.

JCh-4N

This was the second factory model of the JCh-4, produced from 1981 to 1989. It incorporates some design lessons from the JCh-5, which entered service in 1980. The most notable change is the commander's cupola, which is the same model used on the JCh-5G. The central cupola can rotate independently of the 12.7mm heavy machine gun, which is mounted on a separate external ring mount that can be locked in place, locked to the cupola, or else allowed to rotate freely. Like the cupola on the JCh-4G, this requires the commander to expose himself to enemy fire in order to operate the machine gun, but both rapid changes in direction and small adjustments in bearing are easier, and moving the cupola independently from below armor is much easier. When not in use, the heavy machine gun is typically locked in place facing the rear, and from this position it is also easier for the commander to transfer new ammunition boxes from the left side of the turret to the mount.

Five 100-round ammunition boxes for the 12.7mm HMG are stored around the exterior of the turret, three on the left and two on the right. To make space for them, the handles on the rear of the turret were shortened, though they still allow some infantrymen to ride safely on the back of the tank. Starting with the first production model, all JCh-4Ns have smoke grenade projectors arranged around the turret cheeks, originally with four on each side.

Another change on the JCh-4N is the addition of thin steel skirts to the sides of the hull. These provide some protection against older armor-piercing ammunition, though by 1981 APDS and APFSDS projectiles were already standard on foreign main battle tanks. Against high-explosive anti-tank warheads, the side skirts can detonate a projectile prematurely, but at highly oblique angles this slightly increases penetration by improving the standoff distance relative to the underlying hull. The main purpose of the side skirts is to reduce the amount of dust kicked up by a moving tank, thereby reducing dust intake into the engine, improving visibility for the crew, and somewhat reducing the tank's detectability at long ranges.

A few smaller changes were carried out internally. The antenna for the tank's main radio was moved to a new position just in front of the loader's hatch, giving the commander's machine gun a less obstructed traverse arc, and the loader's hatch is of a fixed, non-rotating design with a separate loader's periscope in front of it. The coaxial weapon is a GCh-77 machine gun with a higher rate of fire and better parts commonality with newer Menghean co-axial tank weapons. In theory the loader can change the coaxial machine gun's barrel from under armor, though this process is time-consuming and would typically be done only if the existing heavy barrel were damaged, jammed, or severely overheated.

In an effort to control production costs and focus the flow of scarce new equipment to elite tank units with the JCh-5, the JCh-4N ultimately did not implement a number of planned and proposed electronics upgrades. Despite entering production in 1981 and remaining in production until 1989, it has only rudimentary night vision capability: the commander has an active infrared spotlight and a corresponding infrared sight, but the gunner only has a simple starlight-based image intensifier, the same type used on the JCh-4G's optics. The gunner also relies entirely on stadiametric markings on the gunsight, with neither an older coincidence rangefinder nor a laser rangefinder. In daytime combat and when engaging known tank types at ranges of under 1,000 meters, these drawbacks are relatively minor, but they seriously hinder the JCh-4N's ability to fight at night, especially under thick cloud cover, and limit its accuracy against bunkers and fortifications at long ranges.

JCh-4D

The JCh-4D entered production in 1990, following the lifting of the arms embargo placed on Menghe in response to its nuclear weapons program. It is fitted with more advanced optics and fire-control electronics, including a laser rangefinder unit mounted over the gun barrel. Oddly, the night fighting suite consists of an active infrared spotlight for the gunner, mounted on the right side of the turret, despite the fact that fully passive infrared optics were in use even in Letnia by this time. The gunner's infrared sight is housed in a wider sight enclosure alongside the gunner's optical sight, and the co-axial sight pointing through the turret face on the left side of the gun remains visual-only.

More visible than these changes was the addition of "first-generation ERA" blocks on the hull sides, hull front, and turret frontal arc. The hull glacis plate was also completely redesigned: though nearly identical externally, internally it is considerably thicker, and includes a composite armor array of hardened steel plates spaced at 20mm intervals, much like the composite glacis armor on later models of the JCh-5. These changes collectively added 2.7 tonnes to the mass of the tank, much of it concentrated on the front half of the vehicle. Mobility suffered accordingly, though because of the reduced spacing between the 1st and 2nd and 2nd and 3rd roadwheels, the suspension was able to support the extra weight, even in combination with a mine roller or mine plow.

On the turret rear, the JCh-4D was the first tank in the JCh-4 family to fully do away with the dedicated infantry-carrying hand rails, which had also been absent on the JCh-5. Instead, it installed cage-type storage baskets on the turret rear. Later refits would replace these with bin-type storage baskets.

Major upgrades

Early 125mm prototypes

Beginning in the 1970s, the Menghean People's Army expressed interest in upgrading the JCh-4 with a heavier main armament, specifically a 125mm smoothbore gun based on those entering service with Letnia. The first prototype, designated Sije-Charyang 115 (시제 차량 115, Prototype Vehicle 115), was first tested in 1979, just one year after the baseline JCh-4G entered service. It used the same overall design, including the same turret, but added a 125mm smoothbore gun in place of the 107mm weapon, on a reinforced set of trunnions. The gun was manually loaded, a somewhat time-consuming process when handling two-piece ammunition in the cramped confines of the turret.

Another prototype, Sije-Charyang 117, incorporated a carousel autoloader similar to that which would soon be used on the JCh-5. It also used a new turret with a somewhat lower profile, apparently with provisions to include composite armor layers in subsequent versions. The crew was reduced down to three, and the prototype underwent field trials in 1981.

The timing of these prototypes is unusual, as they appeared at a time when development work on the JCh-5 was already nearing completion; the first service deliveries of the latter vehicle were made in 1982. It appears that they were intended as a fallback option in case the JCh-5 proved too unreliable or expensive. As the JCh-5 proved adequate in both these categories, and possessed superior fighting characteristics, the Menghean military appears to have abandoned these prototypes.

JCh-4.4

Menghean interest in JCh-4 upgrades resurfaced in the late 2000s, as the Menghean Army faced the need to modernize its forces in anticipation of a future conflict with Maverica. Minchŏl responded by funding a series of comprehensive upgrade kits, many amounting to full rebuilds of the tank, in the interest of keeping existing base hulls relevant into the coming decades.

The first such design was the JCh-4 Sinsegi, or "new century," which featured a new welded octagonal turret with composite armor sections over the front half, using the same principle as the turret of the JCh-6D of 2013. The turret retained its original three-man crew, but all rounds were stored in an armored compartment in the turret bustle, with a sliding metal door to contain the blast of an ammunition cookoff. The gun was still of 107mm caliber, but with improvements introduced on the JCh-4D1, such as an improved thermal sleeve, a laser muzzle reference device, and a chrome-lined barrel, all contributing to greater accuracy. The new turret also featured passive night vision optics derived from those on the cheaper JCh-6G. The first prototype was trialed in 2014, but had to undergo continued testing and evaluation as the Ministry of National Defense determined whether it was a cost-effective option.

In 2015, the JCh-4 Sinsegi got a second reveal at an international arms expo, this time with a slightly different turret more reminiscent of that of the JCh-6D and certain electronic improvements. From this arms expo onward it was marketed as the JCh-4.4, denoting a step below the 120mm JCh-4.5.

JCh-4.5

The JCh-4.5 was similar in principle to the 4.4, but it instead carried a 120mm L/48 smoothbore gun, derived from the 125mm L/48 smoothbore of the JCh-6G. This weapon was chambered for Glasic 120mm unitary tank rounds, which were manually loaded and stored in the bustle, which in turn was lengthened compared to that of the JCh-4.4. Because Menghe did not already operate the Glasic 120mm tank round, the JCh-4.5 was almost certainly designed exclusively for export. As with the JCh-5.5, the ".5" designation was apparently meant to show that this vehicle was halfway between the JCh-4 and JCh-5 in its capabilities.

JCh-4.6

One year after unveiling the JCh-4.5, the design bureau of the Minchŏl Tank Factory unveiled the JCh-4.6. This vehicle was similar in concept to the prior two, with a four-man crew, an irregular octagonal welded turret, and manual loading of the main gun. Rather than unitary 120mm ammunition, however, it fired two-piece 125mm ammunition, and used the 125mm L/48 smoothbore gun.

Two-piece ammunition was selected because unitary 125mm tank rounds proved too unwieldy to manually move and load within the confines of the small tank's turret. A full ammunition load consists of 46 projectiles and charges. This includes 32 projectiles (some with partial charges) in the turret bustle, six projectiles in the rear of the fighting compartment, and eight projectiles to the right of the driver. Of the charges, 28 are stored in the rear of the fighting compartment, ten are stored to the right of the driver, and eight are stored in a ready rack in front of the loader, who sits on the left side of the gun, reversing the configuration used by prior Menghean postwar tanks. All charges except for the ones in front of the loader are stored in tubes running through the fuel tanks, providing a small measure of protection against shrapnel detonation. While the first generation of 125mm JCh-4 prototypes struggled to achieve 4 rounds per minute, a well-drilled loader in the JCh-4.6 can reload the gun in as little as 6 seconds, if he uses a projectile from the turret bustle and carries a charge at the ready on his lap. The exclusive use of two-piece ammunition does prevent the use of full-length APFSDS projectiles, but this nevertheless puts the JCh-4.6 on par with most JCh-5 variants, especially combined with the use of passive IR optics and improved visual optics on the turret, which also sports a 12.7mm remote weapon station.

Protection for the JCh-4.6 consists of composite armor hull skirts and Menghean 2nd-generation ERA on the glacis plate and turret face. The turret sides and rear store snorkeling equipment, additional 12.7mm ammunition boxes, and general-purpose storage bins.

JCh-4.7

Unveiled in 2018, the JCh-4.7 was developed in response to a special design requirement from Uskonmaa, which was interested in a comprehensive upgrade to its JCh-4 fleet but flatly rejected the existing models, insisting that the rebuilt tank must be able to fire unitary 125mm ammunition. In order to meet these requirements while preserving a low frontal surface area, Minchŏl's engineers experimented with an asymmetric octagonal turret. The section to the right of the gun's breech contains 17 125mm unitary rounds stored nose-down and moved by a chain link belt. Twelve additional rounds are stored in the rear of the fighting compartment, bringing the total to 29. The gunner sits on the left side of the gun, and the commander sits behind him, following the usual layout of the JCh-4. The asymmetrical turret has 270-degree composite protection, providing better protection against penetrations into the ammunition compartment than other Menghean tanks, though there are no blowout panels as the ready and reserve rounds are stored within the fighting compartment alongside the crew. The ultra-compact turret design left no space for a co-axial machine gun; instead, a GCh-77Ch is mounted on the right side of the turret in an elevating box which protects it against shrapnel and small-arms fire. The belt and ammunition box are not protected. Generally considered a failure, the JCh-4.7 was not ordered by any country other than Uskonmaa.

Full list of variants

Medium tank variants

• JCh-4G - The baseline variant described above, produced from 1976 until 1980. It has no night vision equipment save for a starlight image intensifier, and can only fight effectively in daytime.
  • JCh-4G1 - A designation given to JCh-4G tanks refitted with the hull skirts, smoke grenade projectors, and added glacis plate of the JCh-4N1, with refits beginning in 1985. No known changes to the optics.
  • JCh-4G2 - A designation given to JCh-4G1 tanks that were fitted with the "first-generation reactive armor" of the JCh-4D. While the JCh-4D and JCh-4N1 are effectively identical, the JCh-4G3 lacks the infrared spotlight and over-gun optical unit seen on the former two variants, indicating that it retains the original fire-control system. First seen in 1994.
  • JCh-4G3 - A designation given to JCh-4G1 tanks fitted with slat armor during Menghe's intervention in the Polvokian Civil War. There appears to have been one standardized slat armor kit, but a number of JCh-4 tanks were fitted with improvised slat armor in slightly different configurations.
• JCh-4N - An improved variant produced from 1981 until 1990. Its most visible difference is a new commander's cupola identical to the type used on early models of the JCh-5. This provides the commander with somewhat better periscope coverage and a forward-facing spotlight, which on early variants was a visual-band spotlight. It also features a small rotating periscope for the loader, somewhat improving situational awareness, and a backup optical sight for the gunner. Side skirts are fitted, partly to increase armor protection against glancing hits by HEAT projectiles but mainly to reduce the amount of dust thrown up by the tracks. Eight 82mm smoke grenade launchers are mounted on the turret, with four on each side of the turret face.
  • JCh-4N1 - Designation given to JCh-4N tanks fitted with applique armor on the hull upper glacis plate. The applique armor kit consists of 30mm of hardened steel over 120mm of polyurethane composite with stacked high-hardness steel plates within, and has a mass of 1.5 tonnes. Interestingly, no applique composite armor was mounted to the turret.
  • JCh-4N2 - Designation given to JCh-4N1 tanks refitted to JCh-4D1 standard. These tanks carry the JCh-4D's full night vision suite, missile guidance unit, and laser rangefinder, as well as ERA on the turret and hull sides. In standard production, they do not carry ERA on the hull glacis plate, instead retaining the original applique armor slab, which is not present on the JCh-4D.
• JCh-4D - An improved variant produced in small numbers from 1990 until production ended in 1995. It has an active night vision suite, with a large infrared spotlight on the right turret cheek linked to the gun and an infrared spotlight on the commander's cupola. Both tue gunner and the commander have infrared optics. This system is only effective out to a range of 800 meters and reveals the tank's location to enemy night vision gear while in use, but it marked a significant improvement over earlier JCh-4 models' night-fighting capability. For the first time, a laser rangefinder was added, though it had to be placed in an armored box over the gun. The JCh-4D also carries small ERA blocks on the turret, glacis plate, and hull sides. These are Menghean "1st generation" ERA blocks, and they provide protection against single HEAT charges, but not tandem HEAT charges or kinetic energy penetrators. Owing to the addition of the ERA blocks, the smoke grenade launchers were moved to the sides of the turret, and cage-type stowage bins were added to the rear.
  • JCh-4D1 - JCh-4D modified to be compatible with the YDCh-15 gun-launched anti-tank guided missile, which was introduced in 1993. Externally similar to the JCh-4D, but with a missile guidance box installed over the loader's situational awareness periscope.
  • JCh-4D2 - A major upgrade kit featuring 2nd-generation ERA blocks on the turret face, glacis plate, and hull sides, as well as slat armor on the rear sides of the hull. This newer ERA provides better protection against HEAT rounds, and is also able to defeat APFSDS projectiles. The cage-type stowage units were replaced by bin-type ones, and a snorkel was added to the rear of the turret. When in use, it is fitted to an attachment point on the new loader's hatch. The active IR optics were fully replaced by passive IR optics, giving the JCh-4D2 the same night-fighting capability as the JCh-5D. The gun carries a new thermal sleeve, reportedly more effective than the type on earlier models, and a boresight reference laser kit for aligning the gun and the sights.
• JCh-4GSD - Battalion command vehicle based on the JCh-4G. It has a retractable radio mast which can only be deployed while the vehicle is stationary.
  • JCh-4NSD - Battalion command vehicle based on the JCh-4N. It has the same retractable radio mast, but also features improved fire-control equipment and applique plate armor.
  • JCh-4DSD - Battalion command vehicle based on the JCh-4D. It has the same retractable radio mast, but also features reactive armor on top of applique plate armor.
• JCh-4JGCh - Turretless armored recovery vehicle with a dozer blade, lifting crane, and heavy powered winch.

Production

Variant	Minchŏl	Chikai	Insŏng	Total
JCh-4G	2,050 units	861 units	189 units	3,100 units
JCh-4N	3,624 units	1,779 units	1,367 units	6,770 units
JCh-4D	405 units	0 units	0 units	405 units
All types	6,079 units	2,640 units	1,556 units	10,275 units

The JCh-4 was manufactured at three sites: the Minchŏl Tank Factory in Songrimsŏng, the Chikai Heavy Machine Building Plant in Jinjŏng, and the Insŏng Machine Building Plant in Insŏng. The table on the right breaks down production numbers by type and facility. Note that these totals include tanks produced in Menghe for export, as well as tanks that were produced as combat-variant JCh-4s, but subsequently converted to specialist vehicles. They do not, however, include hulls that were produced from the outset as specialist vehicles.

As of 2022, the JCh-4 is the second most widely produced postwar tank to come out of Menghe, surpassed by the JCh-6.

Operators

• Template:Country data Azbekistan: 1,240 units, of which 305 are new JCh-4G types delivered between 1978 and 1980, 578 are new JCh-4N types delivered between 1981 and 1984, and 357 are used JCh-4N types delivered between 1989 and 1990.
• Dzhungestan: 170 units, all JCh-4G types, delivered between 1978 and 1980. All are new-production models.
• Menghe: 6,173 units. All Menghean JCh-4G models, save for a few museum units, have been exported, and the remaining stock consists of upgraded JCh-4N and JCh-4D models.
• Qusayn: 140 units, all JCh-4G types, delivered between 1979 and 1981. Some are new-production models, while others were delivered secondhand.
• Template:Country data Ummayah: 2,015 units, all secondhand, delivered after 2005. This shipment included all JCh-4G models still in Menghean service.
• Template:Country data Uskonmaa: 525 units, all JCh-4G types, delivered between 1977 and 1980.

See also

• JCh-5
• JCh-5.5
• JCh-6