XK-1 – First Steps

ChieftainWarrior · October 8, 2024, 8:39pm

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XK-1

TL;DR: Pre-production variant of South Korea’s domestic MBT. Only difference to the K1 is a different engine model (but same horsepower).

History
Following the end of WWII, occupied Korea was liberated. After a brief period of self-governance, both the USA and USSR occupied the South and North respectively. The Republic of Korea (South Korea) was officially established in August of 1948, 3 weeks before the establishment of the Democratic People’s Republic of Korea (North Korea). The two states went to war in 1950, lasting until 1953, when Korea was split along the 38th parallel.

The South Korean army was initially armed with American vehicles, such as the M24, M4A3, and M46. These vehicles were eventually replaced by the M48, of which hundreds were acquired. In the mid-to-late 1970s, North Korea began domestic production of the T-62, which they named the Ch’ŏnma. South Korea saw this and realised their tank forces were rapidly becoming inadequate. They first sought to acquire the M60A1, but it wasn’t determined to be good enough against the Ch’ŏnma. Then, they looked at domestic production of the German Leopard 1.

chonma1exer

North Korean Ch’ŏnma – the most advanced tank in North Korea’s arsenal in the 1970s and 80s.

As the Vietnam War intensified, the US withdrew the 7th division from South Korea in 1971, leaving only 43,000 American troops in the country. South Korea believed this would create a serious security vacuum, and in 1976, the government began a program to begin full-scale development and production of a domestic tank. The initial plan was to upgrade the existing M48s to M48A3K and M48A5K standards, then begin license production of the M60A1, building up the capabilities to develop a domestic vehicle. The US did not approve the production of the M60A1 however, and Germany’s policies at the time prevented license production outside of NATO member states.

The South Korean government reached out to various defence companies to develop a tank on par with the Leopard 2 and M1 Abrams. Chrysler Defense in the USA responded to this, and submitted a proposal based on the XM-1 – this was viewed favourably by the South Korean government and development began.

Interesting Fact
American company AAI also submitted a proposal to South Korea in 1978, which had a full-scale mockup built. The tank was 36t, with an 800hp engine and a 105mm M68 cannon.

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Development began under the name ROKIT (Republic of Korea Indigenous Tank). The first prototype was built in 1983 as an automative test rig (ATR), and was named PV-1. PV-2 was built later that year as a fire control test rig (FCTR). Issues quickly emerged, primarily regarding the engine. They were using the Continental AVCR-1790, producing 1200hp, which was found to be too unreliable. Thus, they opted to replace it with the German MTU MB 871 1200hp engine. A total of five prototypes were constructed, but they retained the Continental engine – only the production tanks would receive the MTU engine.

PV-1 undergoing suspension tests

Production of the K1, then nicknamed ‘88 Tank’, began in 1987, carried out by Hyundai. A total of 1,511 tanks were produced, with production only ending in 2011. A number of variants of the K1 exist, including the K1A1 which up-guns it to a 120mm cannon.

K1s during their official reveal in 1987

At least one XK-1 prototype still exists, with it being on display at the War Memorial of Korea in Seoul.

Characteristics
The XK-1 is largely identical to the production K1. The XK-1 is armed with a two-plane stabilised 105mm KM68A1, a license-produced M68A1. The tank can fire a variety of 105mm ammunition – including a number of South Korean designs. While it could certainly fire American rounds like M735 and M774, the K1s are equipped with rounds like K270, K273 and K274. K270 is said to have 152mm penetration at 60° at 3000m, and calculations that give similar values at that range and angle give it a penetration of 292mm at 0° at 0m (the exact same as M735 in-game *currently), and 171mm at 60° at 0m. I couldn’t find any information on K273 but it supposedly has a higher length-diameter ratio than K270. K274 penetrations 480mm of armour at 0° at 3000m. The K1 also has license-produced M456 HEAT-FS (KM456A1) with 400mm of penetration, as well as M393 HESH and KM1 HE rounds. 47 rounds of ammunition are carried. 47 rounds of ammunition are carried.

The main cannon can elevate/depress +20°/-10° without using its hydro-pneumatic suspension. When using it, the gun can elevate/depress +23°/-14°. The turret rotates 360° at a speed of 40°/second. Secondary armament consists of a 12.7mm K6 HMG for the commander, and two 7.62mm M60s – one for the loader and one coaxial. The tank has six smoke grenade launchers on either side of the turret cheeks, for a total of 12.

The XK-1’s fire control system is developed by Hughes, and is the same as fitted to the M1 Abrams. It consists of an Nd:YAG laser rangefinder, as well as a Gunner’s Primary Sight System (GPSS). The GPSS includes a first-generation thermal imager. The commander has the French SFIM VS-580-13 sight, the same as fitted to tanks like the OF-40 and Challenger 2, with only NVDs. This sight gives the vehicle hunter-killer capabilities.

The XK-1 is fitted with a Special Armour Package. This is an American composite armour package, using the same technology as Chobham composite armour as on the the base M1 Abrams. The actual protection values as fitted to the K1 are strictly kept secret, but can be reasonably assumed to be equal to or slightly less than the base M1 Abrams. The composite is fitted on the hull front and turret front and sides. The front hull is said to provide ~400-500mm armour against KE projectiles, and the turret front is likely similar. No sources indicate the XK-1 prototypes were fitted with different armour than the production models.

The XK-1 is fitted with a Continental AVCR-1790, which provides 1200hp. This is connected to a ZF LSG 3000 transmission, which gives the tank 4 forward gears and 2 reverse gears. The production K1 weighs 51.1t, and the XK-1 weighs roughly the same, giving it a power-to-weight ratio of ~23.5hp/t. It has a top speed of 65km/h, with a reverse speed of around 34km/h. The tank is also fitted with a hybrid suspension, with hydropneumatic suspension only on wheels 1, 2 and 6, with torsion bar suspension on the others. As mentioned earlier this gives it an extra +3°/-4° gun elevation. The suspension can only ‘lean’ up or down, it has no side control.

The only visual difference to the production vehicles that I can see is slightly narrower fenders.

Conclusion
The XK-1 is virtually identical to the production K1, and as such is analagous to vehicles like the M1 Abrams. It would be a great fit for a future United Korean tech tree. It could fit in the tree in a few ways, such as: as a tech-tree tank, with worse ammunition than the production K1 to justify a lower BR, or as a premium vehicle counterpart to the production tanks. It would likely have a BR of 10.0 if given K270, although would be slightly let down by its low penetration.

Specifications
Armament

105mm KM68A1
- 9-12rpm
- Ammunition
  - M735 APFSDS
    - 292mm at 0° at 10m
  - K270 APFSDS
    - 292mm at 0° at 10m
  - K273 APFSDS
    - Unknown, higher length-diameter ratio than KM270
  - KM456A1 HEAT-FS
    - 400mm at 0° at 10m
  - M393 HESH
    - 127mm at 0° at 10m
  - KM1 HE
1x 12.7mm K6
2x 7.62mm M60
Vertical guidance
- +20°/-10°
- +23°/-14° (while ‘kneeling’)
Laser rangefinder
Gunner thermals
- First-generation