text/white night
In all the fighter echelons of our Air Force, any news about the F-20 has attracted much attention for a long time. Recently, the five-star red star representing the performance of the F-20 airframe has attracted a lot of attention. The official also clarified that the F-20 has completed a series of actual combat simulation training, obtained zero battle damage and shot down several "enemy aircraft". Record. For the F-20, except for the first time that the belly bomb bay was publicly disclosed at the Zhuhai Air Show in 2018, there is little news that allows everyone to observe closely and reveal important structures. However, recently, a complete internal composition of the J-20 appeared on the Internet, and its mystery was unveiled.
Judging from the exposed photos, the S-shaped inlet, which has been hidden behind the bulge of the F-20 inlet, has appeared in front of everyone. It is this design of the large-curve inlet and the double-bulge design that make the F-20 Become a member of the stealth fighter, and have good strength. According to the current external information, the intake port design of the F-20 engine adopts the advanced DSI intake port design, also known as the bulge intake port design. The function of this bulge is to act as a compression surface while increasing the pressure distribution to "push" the boundary layer air away from the inlet. The design feature of the air inlet fairing lip allows the main boundary layer airflow to overflow to the rear fuselage. It can not only complete the function of the traditional boundary layer partition, but also provide air pre-compression, thereby improving the efficiency of the inlet at high speed and reducing resistance. The
DSI inlet is a bulge at first glance, but its design is quite difficult. The first problem to be solved is the test of the boundary layer. This is due to the development of supersonic wind tunnels in my country. Without numerous relevant data, the DSI inlet will never be completed. While meeting the engine's air intake needs, the maximum speed of the bulge air inlet can reach Mach 2 or more, and at the same time, it reduces the weight concentrated on the boundary layer partition and the corresponding structural reinforcement.
Compared with the F22's Garrett air inlet, the F-20 eliminates the boundary layer partition, vent system and bypass system, and reduces the structural weight by 300 pounds, which is equivalent to a 30% weight reduction in the overall structure. This advantage can save about 3.5 million yuan. In fact, the U.S. military used the optimized DSI inlet in the F35, which reduced production and use costs. This was one of the reasons why it continued to mass produce F35 and closed the F22 production line.
In addition, compared to the F22, the DSI inlet of the F-20 is one of the keys to its high stealth performance. The compression bulge integrated with the front fuselage almost perfectly eliminates the boundary layer. This strong radar reflection source eliminates the radar reflection between the boundary layer partition and the aircraft skin. After the boundary layer partition and the compression swash plate are eliminated, the radar reflection cross section RCS of the F-20 will also be greatly reduced. . In design, the S-shaped air inlet of the big curve effectively avoids the main bomb bay and side bomb bay, and finally transitions to the tail engine. Although part of the air intake is sacrificed and a lot of effort is unavoidable in the design, for the stealth fighter, the stealth of the F-20 is effectively guaranteed. In the past ten years, the US military has done a lot of research on the DSI inlet technology on the F35. Facts have proved that this low-risk and high-stealth design is the most effective.
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