Some sources said that although China has put its domestic stealth fighter J-20 into service, the country’s relevant departments are actively discussing the possibility of purchasing 12 Su-57 fighters from Russia; and military experts think this will probably happen, not only due to Chinese Air Force’s intention to strengthen its combat power, but also because of some deeper reasons.
Russian Technology Corporation’s aviation cluster industry director recently announced that Su-57 has conducted 16 test flights of the brand-new second-stage engine-“Product 30”. He said: At present, the bench test of this advanced engine is still continuing, while the project is also conducting flight tests.
A flight conducted by Su-57 stealth fighter in October examined the characteristics of the new engine in various flight modes, especially its vector tailpipe and oil system operation under negative overload conditions; and 16 flights have been carried out by Su-57 with the new engine.
At the end of 2017, a “Product 30” engine was installed in the left engine compartment of a T-50-2 prototype for its first flight. This aircraft was subsequently called the Su-57LL. “LL” means “Flight Lab” in Russian.
Military experts said “Product 30” represents Russia’s highest achievement in fighter engines and is technically comparable to F119 engine used on the US F-22 fighter.
According to public data, the maximum military thrust of the “Product 30” engine is 11 tons, and the maximum afterburning thrust is 18 tons, which is far better than the 9.5 tons and 15 tons of AL-41F1 engine. So even if the maximum take-off weight of Su-57 exceeds 35 tons, its thrust-to-weight ratio will exceed 1, and the normal take-off weight-to-weight ratio is 1.15-1.2.
“Product 30” will also have a radar barrier at the front of the fan to solve the problem of the stealth of the direct inlet of Su-57 fighter. In addition, it also uses a sawtooth tail nozzle to further improve the overall stealth performance of the aircraft.
According to reports, the temperature before the engine turbine is from 1950 to 2100°K, compared with AL-31F’s data not exceeding 1700°K; the “Product 30” engine is expected to enter mass production stage sometime in 2020, and then completely replace AL-41F1 engine for the production-type Su-57 fighter.