[Special Topic] Goodbye 歼 8： China’s first self-developed fighter began to retire.

The media reported that China 歼 8 began to retire.

Not long ago, relevant media at home and abroad reported that the China Air Force officially retired the J -8 fighter, which indicated that the second generation combat aircraft of the China Air Force had begun to withdraw from the historical stage, and the modernization of the China Air Force had entered a new stage. However, it should be noted that the media did not clearly point out which model of the J-8 it was. According to speculation, it should be related models developed before the mid-1990s, including J-8, J-8I and J-8E. However, with the passage of time, both 歼 8 and 歼 7 will retire like 歼 6 in the near future.

J -8 is the first fighter developed by China, and its birth has experienced difficulties and bumps, among which the hardships far exceed those of other combat aircraft developed by China. However, it is the development of J -8 that has accumulated experience and laid the foundation for China to develop more advanced combat aircraft.

China’s aviation industry started in 1950s, and introduced many types of former Soviet fighters, which was the first step to establish an independent aviation industry. However, with the change of Sino-Soviet relations, the former Soviet Union stopped providing aid to China, so China’s aviation industry had to undertake the heavy responsibility of providing combat aircraft for the Air Force alone.

歼 7 is difficult to fill the "vacuum" of national air defense at that time.

In the mid-1960s, considering that the second generation of foreign combat aircraft had come out, new supersonic bombers and attack aircraft were in service one after another. At that time, the most advanced J -7 combat aircraft in China felt powerless when confronting these combat aircraft in terms of range, firepower and maneuverability, so the China Air Force needed new fighters to counter these new threats. At that time, domestic related units put forward two schemes, one was a single-engine fighter scheme with a new type of large thrust engine, and the other was a modified turbojet -7 engine to improve thrust and develop a dual-engine fighter. Considering the weak foundation in domestic related fields, China Air Force finally chose the latter scheme and named it J -8 fighter.

The J-8 basic model is not equipped with fire control radar.

歼 -8 fighter can be regarded as a large-scale dual-engine of 歼 -7, powered by two turbojet-7A engines, with a single afterburner thrust of about 59 kN. The original idea of airborne equipment is to adopt an all-weather fire control system with fire control radar as the core. However, because the airborne fire control radar failed to make a breakthrough, China Air Force decided to develop the daytime type with radar rangefinder first, and then the all-weather type equipped with fire control radar. Finally, the airborne avionics system of the basic equipment of the J -8 was basically an improvement of the relevant equipment of the J -7, including the range finder of the mine -2 radar, JKK-03 sight and missile firing computer.

Long development leads to poor performance in service.

China Shenyang Aircraft Company began to develop the basic model of the J -8 in 1965, and its first test flight was successful in 1969. However, the aircraft was delayed until 1979, and it was officially equipped with the China Air Force in 1980. The first batch of solo flight was the 11th Aviation School of the Air Force (the predecessor of the current Cangzhou Flight Test Training Center of the Air Force). There are many reasons for the delay in the daytime test flight of the J -8, including subjective reasons caused by the interference of the Cultural Revolution. There are also objective factors such as China’s insufficient understanding of the difficulties and laws of developing new fighters, and the lack of relevant test methods and test equipment. The delay of J -8 is the period of rapid development of foreign aviation industry, and the third-generation combat aircraft has been successfully developed, and China’s aviation industry has also begun a long way to catch up.

○8i is equipped with all-weather fire control system.

In the late 1970s, the Thunder -4 fire control radar originally designed for the J -8 was successfully developed. According to the requirements of the Air Force, Shenyang Aircraft Company began to develop the J -8 all-weather aircraft, numbered J -8Ⅰ (the aircraft was renamed J -8A with the change of the Air Force number in the 1990s). Shelei -4 airborne fire control radar is the first monopulse fire control radar in China, and the maximum detection distance can be 20km for the target with RCS=5 (radar cross-sectional area is 5m2). The aiming -8 optical sight matched with this radar is the first gyro-stabilized sight in China, and the aiming -4, aiming -8 and the airborne missile fire control computer form the all-weather fire control system of J -8.

Improvement of all-weather combat capability of 歼 8I

Regrettably, the development of the J -8′ s Thunderbolt -3 air-to-air missile was slow, so the Air Force decided to still provide the J -8 with the existing Thunderbolt -2 air-to-air missile. According to the requirements of the Air Force, the relevant factories in China have improved the Thunderbolt -2. The improved Thunderbolt -2 B focuses on the problems of anti-jamming and early fuze explosion, mainly using a chilled lead sulfide seeker, and adopting a new optical penetration to improve the detection distance and anti-jamming ability. The original infrared proximity fuze has been improved. In order to improve the maneuverability of the missile, a rudder from Thunderbolt -5 B wing surface has been used, and the overall performance is equivalent to the AIM-9E air-to-air missile in the United States. Other weapons include: two 23-2 double-barrel 23mm cannons, airborne 57mm aerial arrows and other weapons. The new missile combined with the new airborne fire control system has improved the all-weather combat capability of the J -8 to a certain extent. The J -8 all-weather model was developed in 1977, successfully tested in 1982, and was designed and equipped with troops in 1985.

Performance of airborne radar with nose air intake restriction

Although the equipment of the J -8 fighter has updated and improved the level of weapons and equipment of the China Air Force, it has formed a high-low collocation pattern with the J -7Ⅱ fighter equipped at the same time, and became the backbone and backbone of the China Air Force’s combat capability in the 1980s. However, it should be noted that at that time, foreign third-generation combat aircraft had been mass-produced and equipped with troops. The performance focus of the third-generation combat aircraft changed from the high-altitude and high-speed performance of the second-generation combat aircraft to the low-altitude maneuverability, and it was equipped with a more perfect avionics system with all-weather over-the-horizon interception and precision strike capabilities.

However, the J -8 is limited by its original design, so it is difficult to narrow the gap with foreign third-generation combat aircraft by simple improvement. Its nose intake layout limits the performance of airborne fire control radar, because the non-wave-permeable inlet will bounce some radar waves back, forming the so-called "inlet false target". Shelei -4 suffered from this problem in the development process, but when improving MIG -21 series combat aircraft abroad, it also encountered such problems, which greatly affected the performance of airborne radar. In addition, its internal space was limited and it was difficult to install more avionics.

The successful development of 歼 8Ⅱ is still far from the third generation aircraft.

Therefore, from 1980s, China began to develop the J -8Ⅱ aircraft (later renamed J -8B) with air intakes on both sides, that is, to make room for the nose to install large-aperture airborne fire control radar and avionics system. The aircraft was successfully tested in 1984, and was designed, finalized and equipped with troops in 1988.

However, the J -8Ⅱ still retains the J -8 delta wing layout with low aspect ratio. The delta wing has the advantages of low shock resistance and good supersonic performance, but high induced resistance, and low maneuverability and range at high subsonic speed, which is the performance area often used in general air combat. Therefore, while developing the J -8Ⅱ, China started the technical exploration of a new fighter, focusing on improving the maneuverability of the fighter, which is the later J -10 fighter. At that time, the domestic economic and technological foundation was still low, considering that foreign third-generation combat aircraft had spread around China, in this case, in order to improve China’s air defense capability, China decided to import Su -27 fighter as a transition before the new domestic fighter came out, and introduced some advanced fighters to promote the development of new aircraft.

○ 8E developed on the basis of○8I

In the 1990s, with the new fighters being equipped with troops, the position of the J -8 fighters in the Air Force began to decline. However, considering that the number of fighters with all-weather combat capability was limited at that time, the new fighters were used as the "fist" troops and "seed" aircraft of the Air Force, so the J -8 fighters were still used to carry out daily emergency interception combat aircraft. In order to further improve the combat capability of the J -8 fleet, the Air Force was in the J-8. The original SL-4 fire control radar was replaced by JL-7AG fire control radar. Compared with the latter, the detection distance of JL-7AG was increased to about 30 kilometers, and the weapon was converted into Thunderbolt -5 air-to-air missile. At the same time, the optical sight was improved accordingly to support the off-axis launch capability of Thunderbolt -5 B, that is, the omnidirectional radar warning system and chaff/flare dropping frame were added to improve the electronic warfare capability of the aircraft.

The performance of 歼 8E is not as good as that of 歼 8F and 歼 8H.

On the whole, considering that the J -8I has fallen behind and its development potential has been exhausted, the Air Force has not upgraded it on a larger scale, but only made small-scale improvements by using the existing weapons and equipment of the Air Force. The shortcomings of the aircraft, such as lack of over-the-horizon interception capability, low maneuverability and weak electronic warfare capability, have never been solved, and its combat capability in modern high-tech air combat has become lower and lower. Therefore, with the Su -27 and its domestic model and the large number of J -10 equipped troops, the J -8Ⅱ series has also undergone avionics upgrade, with all-weather downward/downward shooting and over-the-horizon interception, and equipped with integrated electronic warfare systems (including J -8F and J -8H still in service), which can perform emergency interception tasks better than J -8 series, so in this case, the China Air Force retired J -8E.

Sniper 8 high-altitude high-speed reconnaissance plane

Because of its transitional nature, its improvement and modification are also limited. In 1980s, considering that the existing fighter -6 aircraft was obsolete, the Air Force decided to develop the fighter -8 high-altitude high-speed reconnaissance aircraft, which was hung with a large reconnaissance pod on its belly and equipped with an imported American KA-112 aerial reconnaissance camera. KA-1l2 camera was an improved panoramic camera based on KA-99A. Automatic inspection and focusing; Automatic oblique focusing; Automatic image motion compensation; The speed-height ratio can be automatically calculated by using the output data of the aircraft inertial navigation system, and it has strong reconnaissance ability to the ground. With the large-range and long-range reconnaissance ability of KA-112, the reconnaissance -8 can conduct imaging reconnaissance in its deep area without going deep into the other area, which greatly improves the tactical reconnaissance ability of the China Air Force.

歼 8 ACT verifier

J -8ACT verifier, the so-called ACT- refers to the active control technology of aircraft. The active control technology and the fly-by-wire control system (FBW) are one of the key technologies to improve the maneuverability, maneuverability and survivability of aircraft. China developed the ACT/FBW technology in 1979, and decided to develop the J -8 ACT verifier based on the J -8 in the 1980s after completing the development of the ground prototype. For this reason, the aircraft is equipped with a duckling on the wing, forming a unique three-wing structure. The fly-by-wire control system of the J -8ACT adopts a four-redundancy structure, which is the first system in China to realize full-time and full-authority fly-by-wire control of static and unstable aircraft. This paper focuses on the relaxation of static stability technology and flight boundary restriction technology, which are of great value to all kinds of aircraft. In 1990, all the development and flight face certification plans of the system were completed. Considering the limitation of the J -8 airframe, China later developed the J -8Ⅱ ACT verification machine with J-8 Ⅱ aircraft, which is equipped with a more advanced three-axis and four-degree digital fly-by-wire control system. These aircraft have laid a solid foundation for the practical application of China ACT/FBW technology.

J-8 extended range type

歼 -8 extended range type; With the development of the situation in the South China Sea in the 1980s, it was difficult for the existing fighters of China Naval Air Force to go deep into Nansha to carry out combat missions. Therefore, the relevant departments asked Shenyang Aircraft Company to develop the J -8 extended-range aircraft, which increased the fuselage fuel tank on the basis of the J -8 daytime model, attached two large auxiliary fuel tanks at the same time, and modified the weapons into the Thunderbolt -2 air-to-air missile. However, considering the limited performance of the aircraft, especially the weak firepower, Compared with the combat aircraft of neighboring countries and regions, it has no obvious advantages, but the aircraft did not continue to develop. After that, China began to develop the J -8D aerial refueling aircraft based on the J -8B.

From today’s perspective, the J -8 is indeed a backward model, and its development progress and the delay of related equipment and weapons also make it difficult for the aircraft to reach the operational capability required by the Air Force. However, as the saying goes, "Without silicon accumulation, it is impossible to travel thousands of miles". We must know that China’s aviation industry started from a blank foundation, and the hardships experienced in developing modern high-performance combat aircraft by itself are beyond outsiders’ understanding. Just like Einstein’s first bench, through the development of J -8, we have accumulated experience and laid a foundation for China to develop more advanced J-10 and J-20, especially these experiences will not be taught by others.

In the 1980s, India assisted France, the former Soviet Union and the United States in developing LCA fighters, but it still struggled for aerodynamic, weight and engine problems, that is, it relied too much on others and lost its own R&D capability, resulting in a strange circle of introduction-backwardness-re-introduction, which fully demonstrated the importance of self-reliance.