The fifth generation fighter jet of Russia, the Su-57, began test flights in 2010 and has produced multiple prototype aircraft for flight testing. It can be said that Russia has invested heavily in the development of the Su-57, which is reflected in the fact that the number of test aircraft is not less than that of its peers such as the F-22 and J-20. However, while the J-20, which first flew nearly two years later than it, had already undergone small-scale testing, the Su-57 had yet to be finalized for mass production, and project development and flight testing were not proceeding smoothly. The frequency of flight testing was low, and the development work was slow. Moreover, the Russian Air Force has significantly reduced the procurement quantity of Su-57, with only 12 planned for the first batch, indicating that it does have some issues.

first,Su-57May be overweight. Su-57 inherited itThe wide spacing structure layout of the engine nacelle of the predecessor Su-27, which is far away from the centerline, does not have an advantage in relative structural strength compared to the narrow body layout where the engine compartment is located near the centerline. Therefore, in order to meet the same maneuvering overload capacity, it is necessary to increase the structural strength. Of course, the cost is also relatively heavier compared to the narrow body structure layout.Previously, the Su-57 had already been exposed during its test flightFatigue cracks appear on the crossbeam of the tail fuselageIn the face of this problem, designers do not have a good solution and can only continue to apply patches, that is, local reinforcement of the structure, which may lead to further overweight of the Su-57.

secondly,Su-57It may not meet the standard on the voyage either.imageSu-57This design, in order to meet the requirements of transonic area law and provide good lift body layout characteristics for the aircraft,The fuselage compartment of the Su-57 is designed to be too flat, and there are also dual segment magazines with considerable length of front and rear columns inside. In order to accommodate more ammunition loads, the fuel tank space inside the fuselage is relatively insufficient. In addition, the aircraft has no other fuel carrying parts except for the front section, wings, and wing body fusion compartment. The F-22 fuselage, wings, wing body fusion compartment, and even the tall vertical tail have fuel carrying parts inside. The Su-57 originally used a Russian made engine known for its huge volume and fuel guzzler, so it is likely that the Su-57 will not meet the expected performance indicators in terms of range.Previously, the Su-57 announced that its range could exceed 4300 kilometers, but now it seems difficult to achieve this figure, at most over 3000 kilometers.

Thirdly, even the Indian partner has doubts about its engine performance.The mismatch between the engine and the aircraft is a major issue with the Su-57, in layman's terms, it is the problem of "a small horse pulling a big car".AL-41F1After all, the (117 engine) is based on the AL-31F, and regardless of the new technologies such as plasma ignition and the replacement of new turbines, fans, etc., it still has the foundation of the previous generation engine. During test flights and even flight performances, the engines of the Su-57 have repeatedly shown signs of being overwhelmed and even experienced accidents such as fires. Russia originally planned to adopt a phased service approach, with the first stage being equipped with AL-41F1 and the Su-57 being equipped first; In the second stage, the target engine "Product 30" will be replaced. But later on, I realized that this was not feasible. So the Su-57 test flight schedule has been repeatedly delayed, and there are also factors waiting for the new engine. Now that "Product 30" has been announced, the Su-57 plans to immediately install it on three test flight prototypes to quickly complete the test flight. But it is still uncertain how mature "Product 30" is and whether it will continue to delay the service of the Su-57.

Source: Military of Strong Countries