The J-20 stealth fighter has been in service for over five years. Yang Wei, the chief engineer of the J-20, explicitly stated in a media interview that a new version of the J-20 has been developed. The photos of the new J-20 fighter jet exposed in the past two years also reveal significant differences from previous versions, with the most obvious being the serrated tail nozzle, indicating that the J-20 may have replaced a new generation of domestically produced engines.

In addition, there have been many changes in the detailed design of the new J-20. For example, the Longbo lens under the belly of the J-20 has been changed to a scalable mode, which can be released when it needs to be visible and retracted when it needs to be invisible. This way, you can switch freely between stealth and non stealth. This design is amazing!

If we observe carefully, during military parades, air shows, and public appearances, the belly of the J-20 stealth fighter jet is not smooth and flat. A small cylindrical device is installed in the middle and back of the belly, which is symmetrically arranged with the forward and backward distributed optical aperture system set on the belly of the J-20. This small cylindrical device is the Longbo lens.

Military enthusiasts who have long been interested in and familiar with stealth fighter jets will definitely be familiar with this device. Whether it is China's J-20 fighter jet, the US F-22A and F-35 series stealth fighter jets, or Russia's Su-57 (crossed out, Su-57 does not require a Longbo lens), they will often be equipped with this device on display. Is stealth fighter jets so fond of this small thing because it can enhance combat performance? The answer is exactly the opposite, Longbo lenses are inherently anti stealth equipment and can seriously affect stealth performance. After being mounted, the stealth performance advantage of the stealth fighter jet, which has been painstakingly designed to reduce the radar scattering area, instantly disappears, just like an ordinary third-generation aircraft becoming clear in front of the radar. The Longbo lens is a spherical multi-faceted refractive lens installed on stealth fighter jets, capable of reflecting and amplifying radar electromagnetic waves in specific frequency bands. The Longbo lens can refract and amplify radar waves in a spherically symmetric manner, allowing it to amplify the effects of many aircraft that should have appeared as small flying objects on the radar interface. The name Longbo lens sounds quite strange, and its specific internal principle is also quite complex and convoluted. We won't discuss it here, just know that its ability is to refract and amplify radar waves. Despite its very small size, it has a large radar cross section (RCS). After being equipped with it, all previous stealth designs can be said to have been in vain. It can make stealth fighters a very prominent target on radar.

According to Yang Wei, the chief engineer of the J-20, the J-20 is a highly stealthy fifth generation fighter jet. In general, active fighter jets are unlikely to rely on their onboard radar to detect the J-20. You should know that by relying on stealth aerodynamic layout and absorbing composite materials, the radar reflection area of stealth fighter jets within a 45 degree range in the forward direction can be reduced to about 0.001 square meters. The centimeter wave fire control radar of fighter jets is difficult to detect the J-20 even within a 10 kilometer line of sight.

As early as the 2016 Chinese Air Force "Red Sword" system confrontation exercise, the newly equipped J-20 easily defeated our army's first four and a half generation fighter jets such as the J-10C and J-16. It is even rumored to have an astonishing record of destroying Blue Army early warning aircraft at 10:0, mainly relying on its excellent stealth ability. The J-20 even easily destroyed fourth generation aircraft while wearing the Dragon Ball lens.

As is well known, the most important aspect of stealth fighter jets is their stealth performance, but stealth performance can be roughly estimated through repeated radar detection. In order to avoid such situations, fifth generation fighter jets often carry a Longbo lens that can amplify radar waves when performing tasks that do not require stealth performance, effectively masking their stealth capabilities. Firstly, to detect stealth fighter jets; Secondly, hide the stealth fighter jets. Discovering stealth fighter jets refers to enabling them to be detected by ordinary radar, so that air traffic controllers can know their specific location and coordinate the navigation routes of various aircraft in the air. This is crucial for the safety of aircraft flight.

Therefore, the Longbo lens has been favored by stealth fighters, and in addition to the J-20, several stealth fighters such as the F-22A and F-35 often carry this equipment. The Russian Su-57 semi suspended stealth fighter has never been mounted on it because its RCS is already large and does not require the help of Longbo lenses! Saying 'hide' stealth fighter jets' refers to keeping the specific stealth values of stealth fighter jets hidden from opponents, hiding the most important stealth capability of our own stealth fighter jets, and only showcasing it during wartime. The specific numerical value of RCS is one of the most important performance indicators of a stealth fighter, which is highly confidential. Even the most open and leak proof United States has never provided specific stealth values for stealth fighters such as F-22A and F-35, only giving a rough estimate. After the stealth fighter is equipped with the Longbo lens, it successfully becomes a non stealth fighter. The outside world cannot calculate its true stealth level without the Longbo lens, and cannot accumulate any useful data for possible future wars.

Upon closer inspection, it can be observed that the US Air Force previously deployed the F-22A Raptor stealth fighter jet in the Middle East to conduct patrol missions over Syria, and last year, the F-35A stealth fighter jet carried the Dragon Lens for the first time in combat operations in Afghanistan. This is precisely for the above considerations, to avoid being collected by countries such as Russia for their stealth performance data. When should stealth fighter jets show off their stealth capabilities, and when should they admit to not being stealth? It really needs to be carefully considered.

The Longbo lens mounted on the new version of the J-20 has undergone significant changes, from a small cylindrical shape to a hexagonal prism device that can be extended and retracted, fully fitting with the belly of the aircraft, without any external connection structure, and the overall volume has also been significantly reduced. From these changes, it seems possible to speculate that the new Longbo lens of the J-20 has the ability to extend and retract, only extending when needed and retracting into the fuselage when not needed, restoring the absolute flatness of the skin at that position. At this point, the J-20 has also regained all stealth capabilities. Compared to the Longbo lens that used to require installation and disassembly on the ground. The new design allows the J-20 fighter jet to switch between stealth and non stealth during a single flight, greatly enhancing its tactical flexibility. When the J-20 fighter jet is required to perform air patrol and air deterrence missions, it can extend its Dragon Ball lens to inform the opponent of its presence, which can deter the opponent. And once the situation escalates and there is a possibility of actual combat, the J-20 can immediately retract its Longbo lens and restore its stealth capability.

The flexible Longbo lens is of great significance for stealth fighter jets. The retractable Longbo lens can give the J-20 stronger combat flexibility, which is definitely an improved design that is worth the money. Even the US Air Force, which has multiple stealth fighter jets and many years of experience in using stealth fighter jets, has not been able to come up with this approach, which shows how smart our researchers are. Will the future J-20 bring us more surprises like this? Let's wait and see!

Source: Military of Strong Countries