Russian culture jet Tupolev Tu-144 by Alexei Tupolev, MiG fighter aircraft series by Artem Mikoyan and Mikhail Gurevich, and Su series by Pavel Sukhoi and his followers. MiG-15 is the world's most produced jet aircraft in history, while MiG-21 is most produced supersonic aircraft. During World War II era Bereznyak-Isayev BI-1 was introduced as the first rocket-powered fighter aircraft, and Ilyushin Il-2 bomber became the most produced military aircraft in history. Polikarpov Po-2 "Kukuruznik" is the world's most produced biplane, and Mil Mi-8 is the most produced helicopter. Famous Russian battle tanks include T-34, the best tank design of World War II,
Sukhoi Su-57 produced, and some believe it to be an implicit announcement of the project's cancellation. The slowing of procurement could be because of the current slow growth of the Russian economy, while the future patches' procurement are for an unknown future; the Russian military could be waiting for the more powerful Saturn izdeliye 30 engine to be ready for serial production. On 22 August 2018, during the International Military-Technical Forum «ARMY-2018», the Russian Ministry of Defence and the JSC Sukhoi signed the first contract for delivery of two serial Su-57s. The contract should be finalized between 2018 and 2020. The prototype's