Panzerkampfwagen XI

PzKpfw XI
A Panzer XI getting serviced during a demonstration
Type	Main Battle Tank
Place of origin	Ostlichtor
Service history
Used by	Ostlichtor
Production history
Designer	Kessel-Hassen
Designed	1969-1976
Manufacturer	Kessel-Hassen
Produced	1979-Present
Specifications
Weight	55.5 tonnes (61.2 short tons; 54.6 long tons)
Length	9.67 metres (31 ft 9 in) gun forward 7.72 metres (25 ft 4 in) hull length
Width	3.7 metres (12 ft 2 in)
Height	3.0 metres (9 ft 10 in)
Crew	4 (commander, gunner, loader, driver)
Armor	Composite
Main armament	1x Karlsbranchen 128mm L/40 cannon (38 rounds)
Secondary armament	2x Biltz & Keckler MG 60
Engine	47.7L V12 liquid cooled turbo-diesel 1500 PS @ 2600 rpm
Power/weight	27 PS/t
Transmission	Automatic (4 forward gears, 2 reverse)
Suspension	Torsion bar
Ground clearance	500 millimetres (1 ft 8 in)
Fuel capacity	1,200 L (320 US gal)
Operational range	550 km (340 mi)
Speed	72 km/h (45 mph)

The PanzerKampfwagen XI (PzKpfw XI) is a main battle tank designed and produced by Kessel-Hassen for the Bodentruppen. It succeeded the PanzerKampfwagen IX.

Development

In the mid 1960s, the Bodentruppen expressed interest in acquiring an improved tank after the initial public demonstrations of the Trinovantan TAG-22. The Bodentruppen were concerned that the obviously larger, more well armed Trinovantan tank would significantly outperform the recently developed PzKpfw IX that was currently in production. In response to this, a design requirement was issued to various Ostlander design firms to create a vehicle that would outperform the believed characteristics of this new potential threat. This new vehicle would have to be resistant to the 105mm rifled cannon across the frontal arc, mount a more powerful weapon than the PzKpfw IX that it would replace, and have at least equivalent road and cross country mobility than the PzKpfw IX. In addition to these requirements, the vehicle's combat-ready weight was not to exceed 60 tonnes.

Siegel AG submitted a significantly modified variant of its PzKpfw IX. An entirely new turret, equipped with an autoloader, a new 110mm smoothbore cannon, and an electric powered traverse system, was developed along with an extensive applique armor package to increase the protection of the hull. These modifications increased the weight of the vehicle from 42 tonnes to 50 tonnes. In order to maintain the vehicle's mobility, a new engine producing 1100 PS was developed. Other, minor improvements were also made to the vehicle, including a highly advanced remote anti-aircraft machine gun, an independent commander's periscope, and a new exhaust ventilation system.

The Kessel-Hassen proposal, in contrast, utilized an entirely new hull and turret of their own design. This turret was equipped with a 128mm smoothbore cannon whose design was derived from the [DESIGNATION] towed anti-tank gun previously in use by the Bodentruppen. Unlike the Siegel AG vehicle, this turret used a more conventional manual loader and hydraulic powered traverse. However, it was equipped with an advanced optical rangefinder and a new two-plane stabilization system. The hull was a proprietary design with little commonality to any vehicle currently in service, using an advanced hydropneumatic suspension and a compartmentalized powerpack that contained a new high-output turbodiesel that produced 1500 PS mated to a hydromechanical automatic transmission that had to be designed specifically for the engine. This prototype weighed 55 tonnes in a complete, combat-ready condition. The most notable feature of the Kessel-Hassen prototype was its novel armor design, utilizing a series of steel plates of varying hardness and ductility separated by an elastic rubber filling. This armor system showed promising performance against shaped charge weapons that were popular at the time, and the interaction between the hardened steel plates and elastic rubber filler material induced a higher than normal stress in APDS perpetrators as they passed through each layer of the armor, giving the armor a level of protection against both threats that was greater than its weight would normally allow.

Kessel-Hassen's prototype PzKpfw XI proposal

Of the two competitors, the Kessel-Hassen vehicle was the clear favorite. The Siegel proposal's protection level, while a notable improvement over the PzKpfw IX it was based off of, was shown to still be below acceptable levels. Additionally, the new engine over-stressed the older transmission used on the vehicle, and could not produce mobility that was consistently equivalent to the PzKpfw IX. Siegel's new turret was also overly cramped, which resulted in an accident where the vehicle's commander had their arm crushed during trials. The electric turret traverse system, while capable of impressive turning speeds, was also prone to failure. The Kessel-Hassen vehicle, meanwhile, showed acceptable or higher marks in most of the conditions set out by the Bodentruppen's procurement staff. While heavier than the Siegel vehicle, the Kessel-Hassen prototype was not only more mobile than its lighter competitor, it was also more mobile than the 40 tonne PzKpfw IX it was to replace. Its 128mm cannon was superior in most regards to the 110mm cannon used by the Siegel vehicle, and it was demonstrated to be able to resist the 110mm cannon used by its competitor along the frontal arc at combat distances, though it was still vulnerable to the prototype APFSDS rounds used by its own 128mm cannon. The new powerpack design was also a highly praised feature, as it allowed for quick access to the entire powertrain of the vehicle for expedited replacement and maintenance. The hydropneumatic suspension system used by the prototype, while it provided fairly unique capabilities such as adjustable ground clearance and forward/backward tilting, was considered to be prone to failure and difficult to maintain. At the conclusion of the demonstrative trials, the Kessel-Hassen vehicle was selected for further development.

Design

Armament

The primary weapon of the PzKpfw XI is the Karlsbranchen 128mm L/40 smoothbore cannon. This cannon is constructed with a chrome-lined barrel to decrease wear from the high-pressure ammunition and is equipped with a fume extractor and a thermal sleeve. The vehicle carries 38 rounds for this cannon, with 14 rounds stored "ready to fire" in the turret bustle and an additional magazine containing 24 rounds located in the front hull. Both magazines are separated from the crew compartment, with the turret magazine being equipped with blow-out panels on the roof of the turret. A variety of ammunition is available for the cannon, including a series of tungsten APFSDS rounds, HEAT, HEAT-MP, and HE rounds. More novel ammunition, such as canister, Enhanced Effect Inert Penetrator, and cannon-launched ATGMs, have also been developed but are not in common use. The most modern variation of its APFSDS ammunition is capable of penetrating over 650mm of steel at a range in excess of 2 kilometers.

For engaging infantry, unarmoured vehicles, and light aircraft the PzKpfw XI is equipped with two Biltz & Keckler MG60 GPMGs. One of these machine guns is mounted co-axially, while the other is mounted on a anti-aircraft pintle mount. Up to 4500 rounds of ammunition can be carried for these weapons.

Protection

Ammunition stowage on PzKpfw XI Ausf.D

Much like the prototype vehicle, the production models of the PzKpfw XI uses multiple layers of high-hardness steel separated by elastic inserts. The hull and turret were modified to allow for a thicker frontal profile with greater protection than the prototype vehicles. This composite armor scheme provides far greater protection from HEAT warheads, which were the principal anti-armor threat of the time, than its weight would normally allow while also providing an acceptable degree of protection from kinetic energy penetrators. The frontal armor of this vehicle can resist the APDS rounds fired from the Trinovantan GHC-17 as equipped on the TAG-22 at most combat ranges. The sides of the vehicle are protected against up to 15mm armor-piercing projectiles. When equipped with protective side skirts, the sides of the vehicle can also be made resistant against a majority of first-generation infantry-portable anti-tank rocket weapons.

The internal structure of the vehicle is highly compartmentalized. Both magazines, as well as the hydraulic powered turret traverse and the hull fuel tanks, are separated from the crew compartment. The turret ammunition magazine is equipped with a blow-out panel in order to prevent a catastrophic detonation from occurring, while the hull magazine and fuel tanks are separated via fireproofed bulkheads. A Halon fire extinguishing system is installed in the vehicle and accessible from the driver's station. This system can be activated manually by the driver or automatically from temperature sensors. An additional fire extinguisher is located in a compartment beneath the main gun. The crew compartment is also equipped with an overpressure system to protect from nuclear, biological, and chemical threats. All vehicles are also equipped with turret-mounted smoke grenade dischargers.

Later upgraded models of the vehicle can be equipped with additional protective measures such as laser warning receivers, applique armor packages, and ATGM jammers.

Mobility

PzKpfw XIs during a military exercise

The PzKpfw XI is powered by a liquid cooled 47.7 liter twin-turbocharged V12 diesel engine. This engine produces 1500 PS at 2600 rpm and 4700 NM of torque at 1600 rpm, and consumes between 3-5 liters of fuel per kilometer traveled. It is a multifuel-capable powerplant. When mated to its 6 speed (four forward, two reverse) automatic transmission, this engine is capable of propelling the vehicle to a governed speed of 70 km/h on paved surfaces and can reverse at up to 31 km/h on any surface. With a full fuel load, the vehicle has a range of approximately 550 km on paved surfaces or 300 km for cross country travel. Due to the modular powerpack design, the entire engine/transmission assembly can be removed and replaced in 40 minutes in the field.

Due to the criticisms of the prototype vehicle, production PzKpfw XIs have a simple torsion bar suspension with seven road wheels and four return rollers per side. The suspension has an object clearance of 1 meter and a trench clearance of 3 meters. It can traverse a gradient of up to 60 degrees or a side-slope of up to 30 degrees without slipping. It can ford up to 1.2 meters of water without preparation, or 4 meters with preparation.

Sensors and Systems

The PzKpfw XI's possesses a simple fire-control computer which receives data from a muzzle reference system and cross-wind sensor mounted coaxially with the gun. The data from these systems provide feedback for the gunner, who uses this and the optical rangefinder to create a ballistic targeting solution. The fire control system also provides full two-plane gun stabilization. The gunner also has access to a dual magnification targeting sight, with 2/10x zoom level and is equipped with an image intensifier for low-light conditions. A backup 8x telescope is also provided to the gunner in the event that the primary targeting sight become inoperable. The commander's station has access to a stabilized panoramic search periscope with a full 360 degree traverse and is equipped with image intensification.

Variants

• Panzerkampfwagen XI Ausf.A - Initial production model, manufactured from 1979 to 1982. Equipped with an optical rangefinder, panoramic periscopes, and an imagine-intensifier for night-combat.
• Panzerkampfwagen XI Ausf.B - Manufactured from 1982 to 1984. Most notable change is the installation of a gunner thermal sight. Other changes include a minor revision to the hull ammo rack design for increased safety and a change to the fuel filters to facilitate faster refueling. Armored coverplates were added to provide additional protection to the commander's periscope and the vehicle's NBC systems. A new towing cable was installed.
• Panzerkampfwagen XI Ausf.C - Manufactured from 1984 to 1985. A series of minor changes, the most notable of which was the installation of a new digital radio set and the replacement of the optical rangefinder with a laser rangefinder.
• Panzerkampfwagen XI Ausf.D - Manufactured from 1985 to 1992. Significant changes to the vehicle, including a new titanium/tungsten armor array, a new all-digital fire control system, the deletion of the cross-wind sensor, an improved fire and explosion suppression system, and an independent thermal sight for the commander. The new armor array increases the vehicle's protection against kinetic energy penetrations by a significant degree, and the digital fire control system allows for the firing of newer types of ammunition including guided missiles. All previous variants of the PzKpfw XI in service with the Bodentruppen were either upgraded to this standard by 1998 or scrapped.
• Panzerkampfwagen XI Ausf.E - Manufactured from 2018 to present. An extensive modernization program to upgrade the PzKpfw XI Ausf.D standard vehicles with technologies researched during the failed MBT 2000 project. Modifications include a new 128mm L/52 cannon, ceramic composite applique armor system, a turret mounted remote weapons station, digital commander/gunner sights, an improved powerpack, and a new 360 degree coverage hardkill and softkill active protection system, among other improvements.
• Panzerkampfwagen XI Ausf.F - Manufactured from 2019 to present. Designation for Ausf.D models upgraded with the composite armor package of the Ausf.E. No other changes to the vehicle are made.

Operators

• Ostlichtor
  • Bodentruppen

See Also

• T-86 Talón
• Tarskvagn-124
• Type 73 Seungli-ho
• T80125