The J-20 is the first time in the history of China's aviation industry to catch up with the world's advanced level, the aircraft has advanced stealth performance, supersonic cruise, high mobility, can carry multiple missiles for long-range attacks, many drills easily broke the blockade of three generations of aircraft and early warning aircraft, within 10 minutes to easily end the battle, let the Chinese air force directly feel: stealthy aircraft is so strong!
The J-20 is highly praised by the Chinese military and military fans. The aircraft is not completely intact at this stage. There are two major hidden dangers in the aircraft, the tail stealth is not good, and the infrared stealth is not enough, both of which are derived from an important component: the engine, the four generations of military engine turbofans with a low base of 16-17 tons of thrust force and a 10 push weight ratio, have been difficult to produce, so the air force has to use imported engines. Recently, the J-20 fighter has a huge breakthrough: the engine has adopted a serrated nozzle, which will be the beginning of the J-20.
The sawtooth engine is an improved type of china's taihang engine with 14 tons of thrust, which is comparable to the russian-made engine used during the j-20 test, and most importantly, china's first stealthy engine, which, though not strong enough, is beginning to prove that china's j-20 is moving towards perfection, with two short plates that have not enough thrust and a hidden defect.
The biggest feature of the engine is the introduction of a serrated nozzle, which has two advantages: it can increase the contact circumference of the high-temperature jet and reduce the jet temperature quickly, and the U.S. F-35 fighter jet also uses this design, which can reduce the infrared radiation by 80% to 90% by using the culvert ratio design.
On the other hand, the serrated nozzle also eliminates the mirror reflection of the blades of the early engine, which is the largest stealth short plate of the J-20 fighter, which is untreated and has a similar effect to the three-generation aircraft, and the current stage of the J-20 rear is completely invisible, a weakness that causes a lot of trouble for pilots to fight and requires special tactics to avoid exposure.
There is also a problem that engine stealth, in addition to the mirror reflection of the spout fish scales, the combustion chamber and turbine blades at the rear of the engine also form a multi-layer angle reflection with the engine housing, similar to the principle of the long-wave lens, which returns the incident electromagnetic wave of the tail to the original way, so special modifications must be made, and the F-35 fighter completely uses the stealth grille to completely block the new engine of the J-20, not knowing whether similar designs have been adopted.
If the nozzle scale is designed with sawtooth, it is not useful for radar stealth, but only for infrared stealth. If the rear radar stealth is to be improved, the internal structure of the engine needs to be operated on. Perhaps the biggest point of view of the engine is the stealth design, which can be preheated for turbofan-15 to verify the engine infrared and radar design in advance, which is also a safe measure to reduce the risk of turbofan-15 engine.
In 2017, the j-20 fighters began to deliver to the air force, and over the past three years, we have been moving forward, first using foreign engines, later using domestic engines, now engaged in stealth design, although not yet get the perfect version of the turbofan-15, but faster and closer.