PL-4 (missile)

PL-4 (PL = Pi Li, 霹雳, meaning thunderbolt) is the first Chinese Semi-active radar homing (SARH) air-to-air missile (AAM), and it has an anti-radar derivative, which is also the first Chinese anti-radiation missile. However, neither entered Chinese service en masse, and both programs were eventually cancelled after very limited numbers had been built for evaluation purposes.

Development
PL-4 program began in March 1966, as the primary weapon that would be used by the proposed Chengdu J-9. The primary contractor was the 612th Research Institute of Chinese Aeronautical Ministry, more commonly known as the Luoyang Electro-Optics Technology Development Center (洛阳光电技术发展中心) nowadays, which became the China Air-to-Air Guided Missile Research Institute (中国空空导弹研究院) in 2002. The primary subcontractor for the propulsion was the 331st Factory, which would later become Zhuzhou Aero-engine Factory (株洲航空发动机厂). PL-4 is based on the American AIM-7D Sparrow IIIa AAM North Vietnam provided to China, after obtaining samples from downed American fighters during Vietnam War. However, barely two month after the program begun, Cultural Revolution started and due to this political turmoil, PL-4 program was disrupted to a complete stop, and it would not be until more than a decade later, well after the end of Cultural Revolution, would the program restart again.

The rocket motor of PL-4 is designated as FG101, and is shared by another anti-radar derivative named Fenglei-7 (风雷7号). The revival of PL-4 was partially due to the decision to develop the anti-radar derivative in January 1979. The designer of the rocket motor was Harbin Ship Engineering Academy (哈尔滨船舶工程学院), the predecessor of Harbin Engineering University, 349th Factory was tasked to manufacture the propellant, 845th Factory was tasked for ground test, and 331st Factory was tasked for final integration. During the propulsion development, the contractor and subcontractors developed new manufacturing techniques, including improvements in installation, new rivet pins, graphite exhaust nozzle, and tolerance. A brand new heat processing method for integrated spin forming was adopted to achieve the high precision engine components, and this was achieved via the use of a special spin forming machinery set specially developed by the Beijing Nonferrous Metal Research Academy (北京有色金属研究院). Once the bottleneck of propulsion has been overcame, both programs went forward with ease, and but the conclusion of political turmoil, namely, the end of Cultural Revolution was an even more crucial contribution in the later development.

PL-4A
With the development of the engine completed, all ground tests were subsequently completed in November 1980. The program proceeded to the second stage, starting in July 1981. Borrowing from the former-Soviet practice of developing two seekers for the same missile, which China considered a good idea, it was decided to develop two versions of PL-4, the SARH guided PL-4A (霹雳4甲), and the IR guided PL-4B (霹雳4乙). In addition to the original Chengdu J-9, PL-4 was planned to equip other Chinese aircraft as well.

By 1984, the first batch produced and ground maintenance equipment were sent to Chinese military for evaluation. Although the missile met its original requirement, th performance was not satisfactory because the requirement itself dating almost two decades ago was obsolete itself. Another factor that led to the eventual cancellation of PL-4 was that during the Sino-USA cooperation in the 1980s, China and US made a deal named project Peace Pearl, where Chinese Shenyang J-8 would be upgraded with American radars. Part of the deal included Chinese purchase of advanced version of AIM-7 Sparrow, making the PL-4 unnecessary. Additionally, China and Italy were also negotiating a deal on the Chinese purchase of Italian Aspide missile, another advanced version of AIM-7, which successfully completed in 1986, and this had further strengthened the Chinese decision to cancel the PL-4 program, which was finalized in 1985, terminating both PL-4A and PL-4B.

PL-4B
IR guided PL-4B (霹雳4乙) is the second member of PL-4 series, developed soon after PL-4A, but it actually entered Chinese service for evaluations earlier than the SARH guided PL-4A. The IR seeker borrowed directly and heavily from PL-2 series AAM, and adaptation of matured technology was the primary reason why its initial completion was faster than its SARH guided counterpart. Another advantage of PL-4B was that due to its IR guidance, the logistic was much simpler than PL-4A, which meant that the cost was also reduced accordingly. Furthermore, unlike PL-4A, most of the ground maintenance equipment of PL-4B was same or similar to that of other IR guided AAM in Chinese inventory, thus further simplifying logistics and reducing costs.

Despite its advantage, it was revealed during evaluation that the performance of PL-4B was not satisfactory. One of the primary drawback was that the 8 km range of PL-8B was simply too short, and offers no obvious advantage to other IR guided AAM China had. Coupled with factors listed above for PL-4A, PL-4B met with the same fate, ending being cancelled in 1985 along with PL-4A.

Fenglei-7
Fenglei-7 (风雷7号) missile is first Chinese anti-radar missile (ARM), with Fenglei (or Feng Lei) meaning Wind (and) Storm. The abbreviated form of Fenglei-7 is FL-7, which should not be confused with the Chinese supersonic anti-ship missile FL-7, abbreviation for Feilong (Fei Long, 飞龙) meaning Flying Dragon. Fenglei-7 is an anti-radiation missile (ARM) derivative of PL-4 missile, sharing the same rocket motor, just like the way AGM-45 Shrike sharing the same rocket motor with AIM-7 Sparrow. In fact, PL-4 was mostly based on AIM-7 while Fenglei was mostly based on AGM-45. Just like AIM-7, complete samples of AGM-45 and AGM-78 Standard ARM missiles were also provided to China by North Vietnam during the Vietnam War, mostly from downed American aircraft, but some were unexploded rounds fired at anti-aircraft sites. Experience gained from Chinese air defense troops sent to help North Vietnam during Vietnam War made Chinese high command realized the need of ARM, but sample of AGM-78 were simply too rare, and the Chinese industrial capability was simply not adequate enough to reverse engineer something as advanced as AGM-78. As a result, China decided to develop its own ARM based on AGM-45, incorporating whatever technologies it could gain from AGM-78, based on the available Chinese industrial capability at the time.

However, Fenglei-7 had a rocky start in comparison to PL-4. As with its American counterpart, China also decided to use the same rocket motor for both the AAM and ARM. Cultural Revolution delayed the program, and it was not until the general headquarter of the People's Liberation Army Air Force made requests to the Commission for Science, Technology and Industry for National Defense (COSTIND) twice, once in 1976 and the other in 1977, did the program finally gathers momentum. Form June 27 to June 28, 1976, under the direction of the 8th Bureau of the Machinery Ministry of the Ministry of National Defense of the People's Republic of China, the National Defense Industry Bureau of Heilongjiang held a conference on the planning of Fenglei-7. Different tasks were assigned to various establishments and factories at this two-day conference. Harbin Ship Engineering Academy (HSEA, 哈尔滨船舶工程学院), the predecessor of Harbin Engineering University was tasked with the design of airframe, control surfaces and engine, and the 349th Factory was tasked with manufacturing these parts, as well as the development of propellant. HESA and Harbin Industrial University were tasked to design the fuse, seeker and flight control system while 254th Factory was tasked to manufacture these parts. On October 28, 1978, Central Military Commission of the People's Republic of China (CMC) formally gave its concurrence to develop Fenglei-7 ARM based on AGM-45, and additional assignment were given to the 349th factory and 254th Factory: the former was tasked to develop ground support equipment while the latter was tasked to develop the test equipment of the part it would manufacture.

In March 1980, two prototypes with FG101 rocket motor successfully completed its test flight at the Base # 31 of People's Liberation Army, with results meeting the original requirements. The same year, the State Council of the People's Republic of China (SCoPRC) and CMC formally designated Fenglei-7 a weapon to enter Chinese service by 1985, and the office of the National Defense of SCoPRC and People's Liberation Army General Staff Department designated Shenyang J-8 as the standard carrier of Fenglei-7. Additionally, in 1980, the 3rd Machinery Ministry of the Chinese Defense Ministry also recommended (and obtained permission) to add Xian JH-7 as the standard aerial platform carrying Fenglei-7. By the end of 1980, the pre-production series Fenglei-7 totaling nineteen has been built, designated as Batch "00". At the beginning of 1981, due to military budget cuts, the 8th Bureau of the Machinery Ministry of the Defense Ministry decided to cancel the Fenglei-7 production program, but many of the subsystems were allowed to continue as research and developmental (R & D) projects. The continuation of the most subsystem was partially due to the fact that the performance of Batch "00" is nearly identical to AGM-45 it was based on, which was not adequate enough to meet the former-Soviet threat China faced, so further development was needed for improvement by incorporating experienced gained from Chinese attempt to reverse engineer AGM-78.

From 1978 onward, the 254th Factory completed two set of 10-cm high frequency (HF) radio fuse based on that of AGM-45, and later another 3 sets incorporating improvement from AGM-78. After indoor tests, field tests were conducted with the help of Unit 81032 and Unit 86001 of the People's Liberation Army in October 1982, with good results. On May 16, 1983, the R & D bureau of the Chinese Aerospace Ministry held an onsite evaluation at the 254th Factory, concluded that the design was successful. Development of rudder control mechanism of the missile begun in 1977, and the first batch of three were proved to either reaching or exceeding the requirement. Field tests of the rudder control mechanism of the missile begun in December 1981 and was completed by the end of 1982. On July 14, 1983, the Chinese Aerospace Ministry certified the development being successful and ready for mass production if needed. From 1978 onward, 254th Factory completed four seekers in two batches (with two in each batch), the first batch was based on that of AGM-45, and the second batch incorporating some technologies of AGM-78. On May 12, 1983, the Chinese Aerospace Ministry certified the design. In 1984, these three R & D projects were awarded the 3rd place in the Awards for the Great Science and Technologies given by the COSTIND. The importance of these projects, however, is that they would be later used on HQ-61 ARM developed later.

After the initial preproduction series Batch "00", Fenglei-7 was terminated. All of the nineteen missiles produced when to the Test Flight Regiment of the People's Liberation Army Air Force for evaluation purposes, and it is believed that all Fenglei-7 missiles produced have been exhausted during these tests. According the evaluation, the performance of Fenglei-7 is nearly identical to that of AGM-45, only slightly better, but not much. Based on Fenglei-7 and the subsequent R & D projects branched out from it, China would later develop a successor based on HQ-61 SAM, incorporating all the expertise gained.

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