Most of the fighters in the Russian Aerospace Forces currently are developed from the twin-engine Su-27 Flanker family.
Specifically, the MiG-29 fighter. This fighter was originally oriented as a single-engine design, to compete with the US F-16 fighter. However, this design encountered a very difficult obstacle. The Soviet Union at that time did not have any jet engines strong and light enough to be installed in the design of the MiG-29.
Designer Mikoyan then had to revise the drawings of the MiG-29, forcing it to use two jet engines instead of a single engine as originally. Basically, at the last stage when the Soviet Union was about to disintegrate, it was very difficult to spend money on research and manufacturing of new generation jet engines. Fighter designers were then forced to use all that was available to them, and the idea of a single-engine fighter was ceased.
In any case, it can still be considered that twin-engine fighters have more advantages compared to single-engine fighters. The US itself, at the present time, has also stopped developing single-engine combat aircraft. The F-16 version, although very popular, has only received further upgrades so far. The F-16 production line was closed in 2017, and in 2019 it was reopened, but only for export.
Compared with single-engine fighters, twin-engine fighters are considered to be more stable in operation. In the event of one engine failure, the remaining engine is enough to bring the plane to a safe landing. Two engines, which means that the aircraft will have two independent power sources for the computer system, and also the hydraulic systems on the plane.
With single-engine fighters, once the engine stops working, the aircraft will immediately fall into a state of loss of control. Especially with today’s modern aircraft, which use a fly-by-wire control system, as soon as the engine is turned off, the computer will also turn off and this complex system will be useless immediately. The American F-16 fighter itself also uses special fuel, along with an electrical energy storage system, allowing the aircraft to operate for an additional 10 minutes after the engine is turned off. After that, the stored energy will run out, and the aircraft will also be uncontrollable.
The single-engine fighter has the advantage of being more compact, lighter, and more fuel-efficient when compared to a twin-engine fighter with the same engine thrust. Even the US F-16 fighters, capable of carrying weapons up to 7.7 tons, are only 300 kg inferior to the Russian twin-engine Su-30. In the future, Russia is looking to replace its MiG-29 fighters with a single-engine fighter. However, up to now, the design of the new Russian fighter is likely still on paper. The first thing Moscow needed was a jet engine powerful enough to carry the fighter.