PT-91

Infobox Weapon
is_vehicle=yes
name=PT-91 "Twardy"


origin=flag|Poland
type=Main battle tank
crew=3
length=6.95 m (9.67 with barrel in forward position) [http://mainbattletanks.czweb.org/Tanky/pt91.htm "Modern Tanks"] ]
width=3.59 m
height=2.19 m
weight=45.9 tonnes
clearance=395 mm
armour=230 mm front of the hull; [http://www.pancerni.abajt.pl/index.php?option=com_content&task=view&id=87&Itemid=99&limit=1&limitstart=1 "Pancerni"] ] composite armour; front and side armor laminated; front, side and top armor behind Erawa-1/Erawa-2 ERA, steel side anti-cumulative screens
primary_armament= 1 x 125mm 2A46M (D-81TM) gun (42 rounds)
secondary_armament= 1 x 7.62mm PKT coaxial general purpose machine gun (2000 rounds)
1 x 12.7mm NSVT anti-aircraft heavy machine gun (300 rounds)
engine=PZL-Wola S-12U diesel for PT-91
PZL-Wola S-1000 diesel for PT-91A
engine_power= 850 HP (634 kW) for PT-91
1000 hp (746 kW) for PT-91A
fuel_capacity=1000 l
suspension=torsion-bar
speed=60 km/h
pw_ratio=18.5 hp/tonne (13.8 kW/tonne) for PT-91
21.9 hp/tonne (16.3 kW/tonne) for PT-91A
vehicle_range=650 km (700 km with extra fuel tanks) for PT-91
550 km for PT-91A [http://mainbattletanks.czweb.org/Tanky/pt91a.htm "Modern Tanks2"] ] Infobox Weapon|is_vehicle=yes
name=PT-91M "Pendekar"


type=Main battle tank
origin=Poland
crew= 3
length= 6.67 m
width= 3.4 m
height= 2.19 m
weight= 46.5 tonnes
armour= composite armour; front and side armor laminated; front, side and top armor behind Erawa-1/Erawa-2 ERA, steel side anti-cumulative screens
primary_armament= 1 x 125mm 2A46MS gun
secondary_armament= 1 x 7.62mm FN MAG coaxial general purpose machine gun,
1 x 12.7mm FN M2 HB anti-aircraft heavy machine gun
engine=PZL-Wola S-1000 diesel
engine_power= 1000 HP (735 kW)
suspension=torsion-bar
speed= 70 km/h
pw_ratio= 16 kW/t
vehicle_range= 500 km

The PT-91 "Twardy" ("tough" or "resilient") is a Polish main battle tank. It is an extensive modernization of the T-72M1 and first entered service in 1995. The PT-91 was designed at the Research and Development Centre of Mechanical Systems OBRUM and is produced by the Bumar Łabędy company. Changes from the T-72 include a new dual-axis stabilized fire-control system, reactive armour, a slightly more powerful 850hp S12U engine, and hydraulic transmission with seven forward gears and one reverse. In 1995 the PT-91 underwent a second modernization, to PT-91A standard, including a 1000hp engine, more advanced fire-control system, and new automatic loader.

History

In the late 1980s the Polish Army modernized all of its obsolete T-55 tanks to the T-55AM "Merida" standard. The successful conversion convinced the General Staff that similar modernization could also be applied to other Soviet-designed tanks made in Poland and used by Polish Armed Forces. In late 1988 it was decided to prepare a project of modernization for the T-72M1 design - using the experience from production of licenced T-72M (obiekt 172M-E3 - polish army designation T-72), T-72M1 (obiekt 172M-E5), T-72M1K (polish army designation T-72M1D).

The Gliwice-based "Research and Development Centre of Mechanical Systems" OBRUM ( _pl. Ośrodek Badawczo-Rozwojowy Urządzeń Mechanicznych) was chosen as the main design bureau. However, initially the work progressed at a very slow pace, mainly because the Polish General Staff was also considering the purchase of a newer version of T-72 (T-72S) or the modern T-80.

After the political changes of 1989 and the dissolution of the Soviet bloc, Polish-Soviet talks on purchase of modern tanks came to a halt and the design of a new Polish tank gained momentum. The first design proposed by the bureau was code-named "Wilk" (Polish for "wolf"), but the project was cancelled. Instead, the priority was shifted to a different project named "Twardy". The basic aim of the conversion of T-72 was to adapt it to the reality of modern warfare and fix its most visible deficiencies. Among those were low mobility, insufficient armour, lack of fire control system and poor stabilisation of the main gun, which resulted in poor firing accuracy. An additional problem was lack of passive night vision aiming systems.

Development

Starting from July 1991 T-72 modernization programs were implemented by the "Bumar" combine which has been serially producing the T-72 under Soviet license. The modernized main battle tank was designated PT-91 "Twardy". From base modification it differs in increased defense, fire control system and engine. In 1993 the Polish Defense Ministry ordered 20 PT-91 tanks to be used for field trials and Armed Forces tests.

The main battle tank's defense from high-explosion projectiles and missiles is increased by the new Erawa dynamic armor developed by the Poland Military-Technical Institute. This defense consists of 394 tiles with explosives, detonating in case of a direct hit. The tiles cover 9m² on the tank. 108 tiles are placed on the turret, 118 on the hull and 84 on each side's anti-cumulative screens. The "Twardy" uses steel anti-cumulative screens instead of the rubber used on the T-72. Erawa's main difference from the Soviet analogs is that Erawa's containers fit almost without gaps while on the Soviet modernised T-72 gaps reach 10 - 15 mm noticeably decreasing defense effectivity. There are two "Erawa" modifications: "Erawa"-1 and -2, differing in weight of the explosives.

Experiments showed that the "Erawa" dynamic defense decreases the high-explosion stream proofing depth by 50 - 70% and undercaliber projectiles by 30 - 40%. Furthermore, explosive containers don't detonate when hit by bullets (up to 30mm), projectile or mine fragmentations, or when covered in burning napalm or petrol.

The "Twardy" is armed with the same 125-mm smoothbore gun 2A46 used in the T-72, fitted with an automatic reloading mechanism which allowed for removing the gun's loader as a crew member, and gave a rate of fire of 8 to 10 rounds "per" minute. Additional armament comprises the 7.62 mm PKT coaxial general purpose machine gun and 12.7 mm NSVT anti-aircraft heavy machine gun. The PT-91 has a thermosmoke device generating smoke screens from fuel and 24 grenade launchers fitted with smoke or anti-personnel frag grenades.

The modernization of the fire control system started by replacing the earlier used Soviet two plane stabilizer 2Je28M with a new stabilizer developed in Slovakia. It has an electronic information block showing the tank's technical condition. Furthermore it informs commander when effective sighted fire becomes in effective because of a excessively high cross-country speed or other reasons.

The Drawa fire control system, developed by Polish engineers, contains the gunner's day sight PCD and the TES thermovision night sight developed by the Israeli company ELOP, the commander's combined day-night passive observation and aiming sight POD-72, a ballistic computer, a laser rangefinder and a data system processing information for the ballistic computer. The sighting of the ballistic computer depends on the target's speed, weather conditions, projectile temperature and projectile type.

The commander uses the control and diagnostic complex US-DK-1 controlling the tank's main systems and displaying information on a monitor. The driver's night sight was replaced by the "Radomka" passive night sight.

The modernized tank's increased weight led the developers to add a more powerful engine. It is a 12 cylinder S-12U diesel engine, a modernized version of the Soviet V-46-6 produced in Warsaw by PZL-Wola (850 hp instead of 780). The main improvement is the modernized fuel and air injection system. This caused a noticeable decrease in the tank's road endurance. The latest "Twardy" variants have the 1000hp S-1000 engine with an turbocharger.

Variants

PT-91 "Twardy"

Production variant for Polish Army, extensively modernized development of T-72M1 with DRAWA dual-axis stabilized fire control, "Erawa" reactive armour, and 850hp S12-U engine. First 20 initial production vehicles were delivered to Polish Land Forces 1993-1994 with another 78 full scale production vehicles delivered 1995-1997, 135 modernized T-72M1 tanks (made in late 80s) delivered 1998-2002. Depending exact configuration Polish Army uses PT-91s in 3 variants known as PT-91, PT-91M and PT-91MA1 [ [http://img149.imageshack.us/my.php?
] ] (the M designation shouldn't be confused with the Malaysian variant).

PT-91Z "Hardy"

("Z" for "Zmodernizowany" – literally "Modernized") Demonstrator of the export variant showed at military exhibitions with SAGEM Savan-15 fire control system, 1,000-hp S-1000 engine with mechanic transmission. PT-91M was designed from PT-91Z. This variant has won a number of stress tests in Malaysia over T-90, T-84 and K1 tanks, and has won the competition for a new Malaysian MBT. Only one prototype was made.

PT-91M "Pendekar"

("M" for "Malaysia") — production export variant for Malaysia with [http://www.sagem-ds.com/pdf/en/D887.pdf SAGEM Savan-15] fire control system, 735 kW S-1000R engine (variant with new, hydropneumatic transmission SESM ESM-350) bringing its top speed to 70 km/h, and a new communications system. Weapons have been changed to a [http://www.kotadef.sk/uk_04_12.html Konštrukta 2A46MS] 125mm tank gun, a 7.62mm FN MAG coaxial machine gun and a 12.7mm FN Browning M2 HB AA machine gun. This variant is also equipped with Sagem VIGY 15 gyro-stabilised panoramic sight optronics, a SIGMA 30 laser gyro inertial navigation system, a PCO SSP-1 Obra-3 laser-warning system, ERAWA 3 Explosive Reactive Armour, Wegmann 76mm grenade launchers and Type 570P Diehl Remscheid GmbH tank tracks. Two prototypes made (renamed PT-91E and PT-91Ex), 48 serial PT-91M vehicles are now in production.

PT-91E/Ex

("E" for "Export") - renamed prototypes of PT-91M used as demonstrators of export variant showed on military exhibitions. Very similar to PT-91M, offered for export to other countries.

Related Vehicles

WZT-3

("WZT" for "Wóz Zabezpieczenia Technicznego" – literally "Technical Support Vehicle") – family of armoured recovery vehicles based on the PT-91/T-72 tank hull. Probably most popular T-72 based ARV on the world with over 400 vehicles delivered to the clients. It is armed with a 12.7 mm (½ in) machine-gun fitted to the commander’s hatch. Standard equipment includes: crane with telescopic jib that can lift a maximum load of fifteen tonnes, front-mounted stabilizing dozer blade, main and secondary winches.
* WZT-3 - A T-72 based variant for Polish Army - 20 vehicles.
* WZT-3M - A PT-91 based variant for Polish Army - 9 new vehicles and 20 WZT-3 upgraded to this standard.
* M-84AI - A M-84A baded variant, made on licence in Yugoslavia - 15 vehicles fo Kuwait
* ARV-3 - A T-72 based variant for Indian Army - 352 vehicles made
* WZT-4 [Nowa Technika Wojskowa - September 2008 page 16 - "Wuzetka" dla Malzezji - by Andrzej Kliński] - A PT-91M based variant for Malysian Army (technicly this vehicle is closly realeted to MID-M) - 6 vehicles

MID

("MID" for "Maszyna Inżynieryjno-Drogowa" – lit. "Engineering-Roading Machine") – Polish engineering tank based on the PT-91 tank hull.
* MID - A PT-91 based variant for Polish Army - 8 vehicles
* MID-M - A PT-91M based variant for Malysian Army - 3 vehicles

PMC

("PMC" for "Pomocniczy Most Czołgowy" – lit. "Auxiliary Tank Bridge") – Polish Armoured Vehicle Launched Bridge is a close support bridge layer. The PMC-90, developed on the basis of PT-91, is able to carry out missions required to operations of combat forces.
* PMC-90 - PT-91 based prototype vehicle with MLC-60 bridge. Not adopted.
* PMC-Leguan - PT-91M based variant for Malaysia equipped with the 26 m (87 ft) long MLC 60 Leguan bridge system. 5 vehicles for Malysia.
* MG-20 Daglezja-G [Nowa Technika Wojskowa - September 2008 page 26 - Most samochodowy MS-20 Daglezja - by Michał Sitarski] - a tracked bridge system, based on lenghten T-72 chasis with one aditional road wheel, equipped with a MLC-70 bridge system. Closly realeted to a truck based MS-20 Daglezja. Courently in development phase, it is expected to replace a T-55 based BLG-67M bridges in Polish Army.

PZA Loara

("PZA" for "Przeciwlotniczy Zestaw Artyleryjski" – lit. "AA Artillery System"; “Loara” means “Loire” in Polish) – antiaircraft artillery system is a Polish armoured radar directed "Self Propelled Anti-Aircraft Gun" system developed in the late 1990s. Based around the "Twardy" chassis, this system mounts an armoured turret holding two Oerlikon KDA 35 mm cannons linked to a radar fire control system. It was planned that it would work closely together with PZR “Loara” (anti-aircraft rocket system) vehicles built on the basis of the PZA Loara but that project is currently on hold. The Loara is an autonomous fire unit capable of performing its tasks independently or acting as a component of a wider air defense system. The system has two radars, 3D search radar and engagement radar. The search radar has a range of 26 km (16 miles) and is capable of tracking and identifying up to 64 targets at once. The radar system can also be operated on the move, refreshing its data every second. The system also has a laser range-finder, TV and FLIR cameras giving the system both all-weather day/night capabilities and the ability to operate entirely passively in a heavy ECM environment. The system also has a reaction time less than 10 seconds. The system can engage aircraft flying at altitudes from very low altitudes up to 5000 m (16,500 ft), and flying at speeds up to 500 m/s (1,125 mph). It is also effective against lightly armored ground and naval targets.

PT-94 "Goryl"

("Goryl" is Polish for "Gorilla") – project of a Polish main battle tank designed using experience gained on PT-91 project. The tank would be similar in its design to Merkava (armor: composite + ERA, main armament: 120/125 mm gun, 60 mm mortar, secondary armament: 7.62 mm PKT coaxial machine gun, 12.7 mm NSWT AA machine gun, crew: 3. This program was also known under the name Anders. The program was cancelled due to lack of funds.

Operators

* - 233 PT-91 delivered between 1995-2002 (older tanks received a number of upgrades to match the new ones) and 38 support vehicles based on the T-72/PT-91 hull (29 WZT-3M armoured recovery vehicle, 8 MID engineering tank and 1 PZA Loara self-propelled anti-aircraft weapon (more vehicles on order - start of the production is expected after positive test with AHED ammunition).
* Malaysia. In March 2002, Malaysia declared an intention to purchase 48 modernized PT-91M Twardy's and 14 support vehicles (6 WZT-3 armoured recovery vehicle, 3 MID-M engineering tank and 5 PMC Leguan - armoured vehicle-launched bridge) for $275 million USD. Delivery began in 2005.
* India. In April 1999, India has ordered 44 WZT-3 armored recovery vehicles, this order was followed by another two orders in April 2002 (another 80 vehicles) and in July 2005 (228 vehicles) – that gives the total number of 352 WZT-3 armored recovery vehicles ordered by India. Vehicles are used to support units with T-72 and T-90 MBT. Deliveries began in 2001. Also India is planning to upgrade its Ajeya Mk1 tanks (local name for T-72M1) to Ajeya Mk2 standard with some elements from PT-91, such as SKO-1T DRAWA-T fire control system and PZL-Wola V46-6 engine.
* Kuwait. In early 90s Kuwait has ordered in Yugoslavia 170 M-84AB tanks (a T-72M1 development), 15 M-84ABK command tanks and 15 M-84AI engineering tanks. The producer decided to buy license for WZT-3 instead of constructing own design. Kuwait M-84AI are almost identical to original WZT-3. In 2005 r. Bumar has offered modernization of Kuwait M-84AB tanks with elements of PT-91 - competing with Croatian proposal (M-84D). Both proposals were refused.

ee also

T-72 -
M-84 -
M-95 -
M-2001 -
PT-91 -
T-80 -
T-84 -
T-90 -
T-95

Notes

External links

* [http://www.globalsecurity.org/military/world/europe/pt-91.htm PT-91 Twardy Main Battle Tank] at globalsecurity.org
* [http://wirtualnepodroze.dziennik.pl/pt91_twardy/pokoj_h,289.html 3D tour of a Polish PT-91 tank] (Java required}