The Russian Air Force today deploys one of the largest fleets of heavyweight air superiority fighters in the world, second in size only that of China, and places a far greater emphasis on these platforms than on cheaper designs from lower weight ranges as most Western powers have. Russia’s emphasis on heavyweight jets came about following the collapse of the Soviet Union, which saw the country retire the majority of it’s fighters which were from light and medium weight ranges - notably including the MiG-21BiS, MiG-23, MiG-27, MiG-29 and Su-22 all of which were in service in their hundreds. MiG-25 heavyweight interceptors also quickly saw retirement due to their high operational costs, with the country unable to retain a fleet even half the size of that in the Cold War era while continuing to induction of newer platforms needed to retain qualitative parity.

As Russia made deep cuts to the size of its Air Force’s combat fleet, it sought to compensate for this by comprising the majority of remaining units of the most capable jets possible - namely Soviet MiG-31 Foxhound heavyweight interceptors and various derivatives of the Su-27 Flanker. The Su-27 entered service as a heavyweight air superiority fighter in 1985, and was designed to go head to head with the elite of the U.S. Air Force, the F-15C Eagle. The fighter would be produced in considerable numbers by post-Soviet Russia both for domestic use and for export, with funding from cancelled or stalled programs such as the MiG 1.44 and Su-47 fifth generation stealth fighters and MiG-31M next generation interceptor diverted to continuing development of more modern Su-27 variants and derivatives. Most notable of these was the Su-30, a twin seat variant with new electronics, engines and sensors and with a greater capability for air to ground and anti shipping to compensate for deep cuts to the strike fleet. The Su-30 was also highly capable in air to air combat, and while carrying more missiles and more powerful sensors than the Su-27 it was also more manoeuvrable with most variants integrating two dimensional thrust vectoring engines - the first serially produced fighters in the world to do so.

With Russia seeking to develop both a modern strike fighter to replace the Su-24M, the only Soviet era dedicated strike platform it had kept in service, the country inducted the Su-34 heavyweight platform into service in 2014. That same year also saw the Air Force begin deployments of the Su-35 heavyweight air superiority fighter, considered the world's first '4++ generation' aircraft, which was designed for a dedicated air superiority role to counter the American F-22 Raptor. While both the Su-34 and the Su-35 were directly derived from the Su-27, the Su-35 was a direct successor in terms of role and had a more similar appearance. The Su-35 boasts a number of advanced next generation capabilities unrivalled by Western and Chinese analogues, including a large payload of 12-14 air to air missiles, powerful new AL-41 engines with three dimensional thrust vectoring capabilities for super manoeuvrability, a 70% reduction in radar cross section relative to the original Su-27, new avionics, electronic warfare systems, infra red sensors and a powerful Irbis-E radar. The Irbis-E is capable of detecting even smaller enemy fighters at ranges of over 400km, and can reportedly track stealth aircraft at ranges of around 80km. This combined with a range of new munitions, most notably the R-37M hypersonic air to air missiles, and a high composite airframe for added durability and a lighter weight, made the Su-35 a world leading air superiority platform.

While the Su-35 is considered capable of going head to head with all existing Western fighters, and other than the F-22 Raptor is thought to retain a comfortable performance advantage over all of them, Russia has looked to develop more capable aircraft in the near future. While the Soviet Union had initially invested in the MiG 1.44 and Su-47 to take on American fifth generation stealth fighters, Russia has sought to develop a more ambitious heavyweight aircraft which it intends to eventually field as a sixth generation fighter. This design, designated Su-57 in July 2017, integrates a range of revolutionary technologies not seen on either the Su-35 or the fifth generation fighters of other countries. These include laser defence systems, artificial intelligence, hypersonic ballistic missiles, laser weapons and even anti gravity suits - the last of which is currently under development to allow pilots to withstand higher g forces and pull of more extreme manoeuvres.

With the Su-57 set to enter service in 2020 after the acquisition schedule was accelerated in 2019, it has led some analysts to question whether the Su-35 will still have a place in the country’s fleet, and why Russia is still manufacturing the aircraft as well as the cheaper and even less capable Su-30SM fighters despite the Su-57 already being combat ready. An analysis of Russia’s defence needs indicates that the Su-35, Su-30 and even later variants of the Su-27 are not set to go the same way as the MiG-23 for the foreseeable future. The Su-35 is still thought to be capable of engaging the vast majority of Western fighters, including the new F-35A and F-15X platforms, on favourable terms. The fighter further has the potential to incorporate upgrades to its design - most notably the integration of an AESA radar derived from that developed for the Su-57. While the Irbis-E is considered sufficiently powerful for the time being, as more powerful AESA radars are developed for the Su-57 as the design further evolves the Air Force is expected to seriously consider integrating these onto the Su-35. Minor upgrades and alterations to the design have already been made based on operational experience gained in the Syrian theatre from early 2016.

The Su-35 is not only a highly capable fighter, but is also much less costly both to manufacture and in particular to operate relative to its newer stealthy counterpart. Thus deploying the fighter alongside the Su-57 allows Russia to retain a larger fleet of heavyweight high end fighters than if it relied on the Su-57 alone, and the balance of the two fighters will be such as to optimise the trade of between quantity and combat prowess. This draws significant parallels to the United States’ and China’s own acquisition strategies, with the countries seeking to complement their F-22 Raptor and J-20 Mighty Dragon fifth generation heavyweight fighters with advanced fourth generation heavyweights - namely the F-15EX and the J-11D and J-16 which are similarly much cheaper both to acquire and to operate.

The Su-57 is designed primarily to counter sixth generation threats, with at least three sixth generation fighters currently under development in the United States under the Air Dominance Fighter, Penetrating Counter Air Fighter and F-X programs. This and its ability to serve as a high endurance maritime strike fighter armed with hypersonic ballistic missiles are the primary roles which the Su-35 will be unable to perform, which make the Su-57 vital to Russia’s military modernisation efforts. It can thus be said that both aircraft are vital and highly complementary. It remains uncertain whether Russia will induct the Su-57 in its original form into service in large numbers, with just 76 now on order, or whether it will seek to acquire more sophisticated derivatives of the platform. If looking to the precedent set by the Su-27 program, the fighter will likely be developed into a ‘Su-60’ and possibility a ‘Su-65’ before 2030 - with greater use of more advanced composite materials, a stealthier airframe, superior sensors and electronics and new more powerful engines. These aircraft will have a much bigger capability gap with the Su-35, and it is them which Russia appears to have the greatest interest in acquiring.