BSCh-12

The BSCh-12 is a type of amphibious infantry fighting vehicle developed in Menghe for the Menghean Marine Infantry. It is the newly-introduced successor to the BSCh-6, with a heavier armament, better protection, and improved troop carrying capacity. It is the first postwar armored fighting vehicle to be developed exclusively for Menghe's Marine Infantry, in contrast to earlier vehicles, which were developed for both the Army and the Marines.

Development

From the 1980s up to the late 2010s, the main amphibious APC of the Menghean Marine Infantry was the BSCh-6, a light tracked vehicle developed during the late years of the Democratic People's Republic of Menghe. The BSCh-6 introduced a number of features carried forward to the BSCh-12, including a rear-engine layout to improve balance at sea and three side-by-side seats in the front. Beyond these basic features, however, the BSCh-6 still had a number of drawbacks. First, its seakeeping performance was worse than expected, in part because of its low freeboard forward and aft. Second, it had poor armor protection: it could only withstand 12.7mm fire over the frontal arc and rifle-caliber fire from all around. Even the frontal protection was inadequate against Sieuxerrian 13.2mm and Maverican 14.5mm armor-piercing rounds. Third, its armament was very poor. Early versions of the BSCh-6 were armed with three 7.5mm machine guns in firing ports, one of them on the exit hatch. Later versions introduced 12.7mm HMG turrets and 30mm grenade launcher turrets, but in both cases the turret was operated by the squad sergeant rather than a dedicated gunner, a fourth problem.

The Menghean Marine Infantry generally tolerated these problems in the 1990s, 2000s, and early 2010s, treating the BSCh-6 mainly as an armored taxi to the shore rather than a well-rounded fighting vehicle. Amphibious operations during the Innominadan Crisis, however, brought the problems with the type into full view. Menghe's amphibious operations were ultimately successful, but they highlighted problems with the type and intensified demand for a replacement.

By the end of 2014, when the Marines' demand for a new vehicle intensified, several of Menghe's private and public design bureaus had already started work on new amphibious fighting vehicles. Samsan Defense had already built a working prototype SCh.507, an amphibious IFV with a Type 110 35mm autocannon in a manned turret. The SCh.507 carried eight dismounts and three crew, like the BSCh-8 IFV, but it was also fully amphibious due to its low-profile aluminium hull. In conjunction with representatives from the Marine Infantry, Samsan Defense developed a new derivative, SCh-511. This version used an unmanned turret, initially armed with a 30mm autocannon. The remote armament was later upgraded to a 35/50mm autocannon in an exposed remote turret, which was then replaced by the enclosed turret on the production model.

These changes drew a great deal of skepticism from the Menghean Ministry of National Defense. Procurement staff with prior experience in the Menghean Army were wary of the drawbacks of a remote weapon station, and expressed concern that the crew would have no way of manually traversing the turret if the power controls failed or manually clearing the gun if it jammed. The Marine Infantry, however, were impressed with the space savings from the new design: despite having a much heavier armament than the BSCh-6, and fitting inside the same deck parking footprint, it could carry three permanent crew and ten dismounts.

The BSCh-12 was accepted for service in late 2020, with mass-production beginning early the next year. The vehicle was first revealed to the public at the Victory Day Parade on July 27th, 2021.

Design

Layout and construction

The basic internal layout of the BSCh-12 is very similar to that of the BSCh-6. The engine is located in the rear of the hull, providing a counterweight to the heavier armor in the front. The dismounts sit forward of the engine, though in the BSCh-12 they face inward rather than outward and all ten are lined up in two rows. The three crew members sit side-by-side in the front of the hull, with the gunner on the right, the driver in the center, and the commander on the left. This layout is only possible due to the adoption of a remote turret, which sits on top of the hull compartment instead of penetrating into it. The gunner relies entirely on the remote gunsight from the turret, while the commander has forward and forward-right-facing periscopes in addition to a video feed from the visual and IR spectrum sight on the remote weapon station atop the turret.

As on the BSCh-6, the rear-engine layout means that the crew must climb over the engine in order to disembark. The BSCh-12 complicates this process even further by extending the roof armor all the way to the rear of the hull, creating two narrow "passageways" over the engine with the air conditioning plate in between. To disembark, the rear two passengers lift open the two 2.4-meter-long roof hatches, climb over the engine cover panel to the rear, then open the rear doors and release the rear steps. The long roof hatches, 15mm thick and 81cm high, offer side protection against shrapnel and small-arms fire during disembarking, and their front edges nearly line up with the turret, which blocks small-arms fire from the front. Overall, the "trench" created by the raised hatches, recessed walkways, and turret is 1.35 meters deep, allowing a hunched-over soldier to run over the engine and drop down behind the vehicle without exposing his head to enemy fire.

In order to save weight while maintaining a high level of protection, the hull of the BSCh-12 is made from aluminium rather than steel. For further weight reduction, the designers used partial monocoque construction, with the aluminium plates themselves forming the structural supports for the hull. During the design process, however, the increasing mass of the turret made a full monocoque build impossible. Instead, aluminium supports were added inside the hull to support the turret from below.

Protection

Official Menghean sources claim that the baseline variant of the BSCh-12 is protected against 30mm armor-piercing shells from a range of 200 meters over the 40-degree frontal arc. It achieves this protection with a combination of thick aluminium armor, sloping, and spaced plating. The upper glacis plate, which comprises 20% of the height of the hull, is 18mm thick and sloped at 82 degrees from vertical, for an effective thickness of 129 millimeters. It is also lined with external reinforcing bars at 15-millimeter intervals; an incoming projectile strikes these before impacting the sloped armor itself. The center front plate is 70 millimeters thick, angled at 30 degrees from vertical, and it also has the 10mm hardened steel water vane in front of it. The lower glacis plate is 50mm thick and angled 60 degrees from vertical with a 10mm hardened steel dozer blade in front. Furthermore, the thick double bottom of the hull is directly behind this plate, so penetrating munitions on its lower edge will not strike the interior of the vehicle. All of these plates are sufficient to stop 30mm APFSDS ammunition from Maverican 2A42 and 2A72 autocannons, given their angle, armor efficiency, and spacing.

Behind the front armor is the vehicle's main fuel tank. The fuel tank is fully self-sealing, and as it empties, a separate valve releases non-flammable gas into the empty space above the fuel surface. When the fuel tank is full, it serves as additional protection for the hull, catching spall fragments and even penetrating projectiles before they can impact the crew and passengers.

The hull side armor is thinner, measuring 43mm on the hull sponsons and lower hull sides. By itself, this is sufficient to stop 30mm and 25mm autocannon fire at an angle of 20 degrees from the vehicle's centerline, but this only results in a 40-degree forward protected arc. At the same 200-meter range, the side armor can withstand 23mm armor-piercing ammunition at angles of up to 30 degrees from the vehicle's centerline. The side and rear armor can also withstand rifle-caliber (7.62×54mmR or 7.5×54mm) armor-piercing ammunition from all ranges, and it offers good protection against shrapnel.

The turret armor is significantly weaker than the armor on the hull. While armor thickness data are not available, Menghean sources claim that the turret can withstand 14.5×114mm fire from the 40-degree frontal arc and 13.2×96mm fire from the 60-degree frontal arc, both from a range of 200 meters, and rifle-caliber armor-piercing ammunition all around. Autocannon ammunition of 23mm caliber or higher, however, will penetrate it at most combat ranges. Menghean designers judged this shortfall to be acceptable given the unmanned design of the turret, which ensures that no crew would be killed in the event of a penetration. Furthermore, because the turret is mounted atop the hull roof, the ammunition is fully isolated from the crew compartment and an ammunition cookoff will not injure the crew.

The hull floor armor is 10mm thick and mostly flat, with no V-shaped design to deflect mine blasts. The front section of the hull has a reinforced and spaced double bottom to protect the three forward crew from mine blasts, but this only extends 1.1 meters into the hull before tapering off. The crew and passengers do have cushioned seats which attach to the hull sides rather than the hull floor, offering some shock protection. Overall, the BSCh-12's mine protection reflects a primary emphasis on conventional anti-tank mines with small blasting charges rather than high-yield improvised explosive devices and roadside bombs.

Armor upgrades

There are several applique armor kits which improve the BSCh-12's protection even further. The simplest adds thin hardened steel plates over the hull sponsons and upper tread return paths. Though less than 10mm thick, these plates can defeat 12.7mm and 13.2mm saboted light armor penetrators with simple tungsten APDS projectiles by fracturing the penetrator before it strikes the hull. Capped 14.5×114mm armor-piercing rounds are still able to penetrate the side armor at angles of less than 30 degrees off-normal. This thin armor plate scheme appeared during prototype testing, but it was apparently not accepted for service.

A more advanced armor scheme, unveiled with the first batch of vehicles at the 2021 Victory Day parade, consists of large reactive armour blocks mounted on top of the aforementioned hard steel strike plates. The total mass of the applique armor is slightly over 4 tons, but because the reactive armor blocks are filled with a combination of foam and air, they are net buoyant and do not reduce the vehicle's amphibious capability. Official sources claim that a BSCh-12 with full applique armor is able to defeat 14.5×114mm armor-piercing ammunition from all ranges and angles, 30mm APFSDS ammunition from 30 degrees off-center, and 23mm AP ammunition from 60 degrees off-center, as well as high-explosive anti-tank ammunition from man-portable rocket launchers.

Curiously, test versions of the BSCh-12 revealed to the public at the 2021 Victory Day parade did not feature the Jŏgran-un active protection system. It is not known whether Jŏgran-un compatibility is planned for later variants.

Armament

The main armament of the BSCh-12 is the Type 110 35mm autocannon. In its baseline variant, this weapon is chambered in 35×228mm ammunition. However, by swapping out the barrel and a few other small parts - an upgrade which can be performed in a front-line workshop or divisional arsenal - it is possible to re-chamber the weapon to fire special 50×330mm ammunition sized to the outer dimensions of the 35×228mm cartridge. This upgrade does not affect the ammunition feed mechanism, the number of stored rounds, or even the rate of fire, and it greatly increases the autocannon's armor penetration effectiveness.

The autocannon on the BSCh-12 uses the linkless feed mechanism developed in 2014. Ammunition is fed from two 38-round boxes, one on each side of the gun. Usually, one box is loaded with APFSDS ammunition and the other is loaded with either impact-fused or smart-fused high-explosive ammunition. These boxes are fixed to the receiver and feed through the trunnions, and they rotate with the autocannon as it elevates to keep the feed aligned with the receiver. With the aligned linkless feed system, the Type 110 autocannon can fire at 200 rounds per minute, compared with 90 rounds per minute on turntable-fed Type 110 autocannon mounts. A reserve ammunition storage box forward of the main feed boxes stores 120 rounds of ammunition, bringing total 35mm ammunition capacity to 196 rounds. This unified forward linkless feed box can store a mix of APFSDS and HE or Smart HE rounds. In restocking mode, the gun lowers to a fixed angle of 0 degrees and an automated ramming system transfers rounds from the reserve feed boxes to the ready feed boxes at a rate of 90 rounds per minute, enough to fully restock both boxes in 51 seconds.

Based on international penetration charts for 35×228mm APFSDS, the BSCh-12's main armament can penetrate a 70mm RHA plate sloped at 60 degrees from 100 meters, or a 55mm RHA plate sloped at 60 degrees from 2,000 meters. These are equivalent to line-of-sight penetration distances of 140 and 110 millimeters respectively, sufficient to defeat the frontal armor of most existing IFVs at typical combat ranges. The upgrade to 50×330mm ammunition would be implemented if an enemy country introduced an IFV protected against 35mm APFSDS ammunition over the frontal arc.

Smart-fused 35mm high-explosive ammunition can be programmed to detonate at a specific range from the vehicle, making it useful for attacking infantry in trenches, behind windows, or lying down in the open. It is also very effective against light helicopters and small drones, functioning like a variable-time flak shell. Notably, the smart-fused high-explosive shell for the BSCh-12 is different from the smart-fused anti-aircraft shell for the DGP-35-2, which detonates in front of the target and releases 152 submunitions in a shotgun-like pattern. The BSCh-12 can be loaded with smart-fused anti-aircraft ammunition and has the necessary equipment to arm it correctly, but because there are only two feed boxes, this ammunition type is not typically loaded. Due to their elite status, Marine Infantry units with the BSCh-12 would likely receive full loads of smart-fused HE ammunition, but as the war progresses and smart-fused ammunition stocks are depleted, they can also be loaded with simple impact-fused HE cartridges.

Operators

• Menghe