In 2015, China finally successfully signed a contract for the introduction of 24 Su-35 fighters, and the 117S engine carried by it attracted much attention. Not only because this engine is used in the first stage of the Russian fifth-generation fighter Su-57, but also because of its strong thrust, it is said that it can fly to supersonic speeds even without afterburner. However, this raises the question: did our country really get the engines used by the Russian Su-35 by introducing the Su-57?
The 117S engine is a product of the second stage of the Russian "117 Project", which is headed by the general designer Marchukov. In this program, Russia first developed the 117A (Al-41F1-A) engine, and subsequently improved it on its basis, introducing the 117S (Al-41F1-S) engine. However, in fact, the 117 series engines are derived from the Al-30FP vectored thrust engine of the Indian Su-31MKI and were originally planned for the MiG-1The Al-41 engine of the 44 can be regarded as a derivative of the AL-31F family.
Compared to the Al-31F, the diameter of the 117S increased from 905 mm to 932 mm, the air flow increased from 112 kg sec to 122 kg sec, and the thrust increased by 16% from 125 tons were raised to 14 tons, while the emergency maximum thrust reached 145 tons (sacrificial life). The thrust of the 117s is even more than 99m1 of the 135 tons. And in 2015, when our country signed a contract to buy the Su-35, our country did not yet have such a high-thrust engine.
However, it is worth noting that although the Russian name of the 117S engine used in the first stage of the Su-57 is -41 -1, and the Russian name of the 117S engine carried by the Su-35 is -41 -1, the difference between the two is only one letter "C", but in fact there is a big difference in performance, but many domestic military experts often confuse the two.
First, there is a big difference in weight. The Su-57 uses a -41 -1 engine that weighs 1,400 kilograms, while the Su-35 uses a -41 -1 engine that weighs 1,604 kilograms, a difference of 204 kilograms in engine weight alone. This means that the Su-57 can reduce the weight of the Su-35 by 408 kg compared to the engine alone, but in fact the weight difference on the aircraft may be much more than 408 kg.
There is a saying that for every 1 kg of engine weight added, the empty weight of the aircraft increased by 5 kg. Because the engine is in a state of high temperature, high pressure and high speed, the torque generated by the high-speed rotation of the engine is supported and balanced, so that the aircraft needs to pay a great price in terms of structural weight. The difference between the 41 -1 and -41 -1 is 408 kg, which translates to the empty weight of the Su-57 and Su-35 is about 2 tons. In fact, the empty weight of the Su-57 is 18 tons, and the empty weight of the Su-35 is also 18 tons, but it is worth noting that as a fifth-generation fighter, the Su-57 also has additional weight from the bomb bay, telescopic launcher and its actuating device, etc.
Second, the difference in thrust is also large. The Su-57 -41 -1 engine has a thrust of 9 in the middle5 tons, afterburner thrust reaches 15 tons, this thrust is already equivalent to a turbofan 10c. The Su-35S's -41 -1 engine has only 8 thrust in the middle8 tons, afterburner thrust of 145 tons, which is equivalent to only 10b turbofan. The gap between the Turbofan 10b and the turbofan 10c, the latter of which allows the Turbofan 15 to be reconstructed.
Third, there are also differences in thrust-to-weight ratio and life. The thrust-to-weight ratio advertised in the 117s is 8 9 (according to the Russian standard), and the whole life cycle is more than 4000 hours. However, this most likely refers to the -41 -1 engine of the Su-57. Another version is that the thrust-to-weight ratio of the 117S was changed from 31 to 7 of the Al-7F due to amplification8 down to 75 (according to the Russian standard), this is likely to refer to the -41 -1 of the Su-35, and the lifespan is about 2500 hours. Although there is no direct data on the thrust-to-weight ratio and life of the -41 -1 and -41 -1, if the Chinese 117S-41 -1 engine thrust-to-weight ratio is 7 if the Chinese standard for reducing the configuration when purchasing the Su-355. The life span is about 2500 hours.
Although the Su-35BM engine used by Russia has passed reliability tests by spraying a high-temperature ceramic coating and a number of other new technologies to increase the temperature before the turbine and increase the service life, this engine will not be given to China. However, with the advent of turbofan-10b and turbofan-10c, China is no longer completely dependent on Russia.
In addition to these, the FADEC (Engine Digital Control System) of the 117S-41-1 is also of great reference. The system can accurately control the engine revolution, vector nozzle angle, stator blade angle, fuel injection volume and other parameters, saving fuel and prolonging engine life. Because FADEC mainly relies on long-term massive tests to achieve, and China's technology accumulation in the field of aero engines is relatively small, therefore, China's technical foundation in FADEC is relatively weak. Now with 117s -41 -1 as a reference, China's development in this area will be twice as effective with half the effort.