PT-91 Twardy / Polish Main Battle Tank

The PT-91 Twardy is an improved variant of the Soviet T-72 main battle tank. The PT-91 was developed in Poland in the early 1990s. Production of the PT-91 Twardy tanks for the Polish Army were completed in 2002. A total of 233 tanks were delivered. Currently Polish Army also operates 120 older T-72M1 tanks (plus 470 in storage) and a number of ex-German Leopard 2A4 and Leopard 2A5 tanks. The older Leopard 2A4 tanks are planed to be upgraded to Leopard 2PL standard.
In 2002 Germany donated to Poland a number of Leopard 2A4 tanks from the German army stocks. Some former units equipped with Twardy, were reequipped with the Leopard 2A4 and 2A5 tanks. In turn units formerly equipped with the T-72M1 tanks were reequipped with the Twardy tanks. It was planned that PT-91 Twardy tanks will be operational until 2030. In 2023 it was announced that 60 PT-91 Twardy tanks will be delivered to Ukraine in order to defend against the Russian invasion.
Twardy's protection is enhanced by utilizing indigenously developed ERAWA explosive reactive armor blocks. There is a total of 394 ERAWA blocks covering front of the hull and the turret. These blocks are placed virtually without gaps to each other. It is worth mentioning that explosive reactive armor blocks on the Soviet of the Cold War era usually have 15 mm gaps or even more, thus reducing overall protection. Tests shown that ERAWA blocks improve tank's protection by 30-70% depending on the ammunition type used. However armor of the PT-91 can not withstand modern Western 120 mm tank gun ammunition fired from 2,000 m range.
The PT-91 Twardy is armed with a 125 mm main gun, which is similar to that, used on the T-72. The gun is fitted with an autoloader. The PT-91 Twardy has new gun stabilization system and new fire control system. Other systems and sights have also been improved.
Secondary armament consists of coaxial 7.62 mm machine gun and roof mounted 12.7 mm machine gun.
Vehicle has a crew of three, including commander, gunner and driver.
The PT-91 has more powerful engine, comparing with the T-72. It is fitted with the S-12U diesel engine, developing 850 horsepower. There was also developed a S-1000 turbocharged diesel engine, developing 1,000 horsepower.
A comparison test was made in Poland in order to compare reliability of the Polish PT-91 and Leopard 2A4 tanks. It appeared that tanks with similar mileage (19,000 km) showed different results. Distance between failures of the PT-91 was only 25 km and it took on average 3.2 days to repair the tank. On the other hand distance between failures of the Leopard 2A4 tank was 174 km and it took on average 1.3 days to repair the tank. Most failures of the PT-91 Twardy were related to its engine, electrical installation, armament, fire control system, and communication systems. So the ageing PT-91 tanks can be seen as rather unreliable combat vehicles, that are troublesome to keep in operational order.