HQ-61

The Hongqi-61 (Hongqi = Hong Qi, 红旗, meaning Red Flag or Red Banner) is the first generation Chinese SARH guided surface-to-air missile (SAM). It is classified by Chinese as a low-to-medium air defense missile, and the series includes both land-based and ship-born versions, and an anti-radiation version and air-to-air version (designated as PL-11) have also been developed. The naval and anti-radiation versions have been retired from Chinese service but PL-11, the air-to-air version and HQ-61A, the land-based mobile version are still currently in limited service with the Chinese military.

History
In August, 1965, Chinese Central Military Commission (CMC) issued the request to develop a medium range SAM. The 25th Research Institute of the 2nd Academy of the Chinese Defense Ministry (CDM) was tasked to do the feasibility study. A month later, in September, 1965, the plan was rapidly finalized and the project was code named Project Hongqi-41 (红旗4l号, Hongqi = Hong Qi, or 红旗, meaning Red Flag or Red Banner). Preliminary design work begun in the same month, and in January, 1966, the plan formally became a national project, and the missile was designated as Hongqi-61 (HQ-61), to reflect the time of its creation and the technologies of 1960’s. By March, 1966, design was in full swing by the 25th Research Institute. In 1967, CMC changed the project to a ship-born SAM due to the urgent Chinese need of fleet air defense, and the primary contractor was changed from the 25th Research Institute of the 2nd Academy of CDM to the 2nd Electro Mechanical Bureau of Shanghai (later reorganized as Shanghai Aerospace Bureau in the early 1980s).

In May, 1970, People's Liberation Army Navy, the 7th Academy of the 6th Ministry of CDM, and 2nd Electro Mechanical Bureau of Shanghai jointly set future developmental plan, and begun the development of HQ-61 series SAM. Contractors and subcontractors involved in the development and production of HQ-61 series SAM included 12 research institutes, 11 factories, 2 test facilities and other smaller players. To reduce risk and costs, a plan of developing a land-based version first, designated simply as HQ-61, and then based on the expertise gained from HQ-61, a naval version designated as HQ-61B would be developed, though other equipments of HQ-61B would be developed in parallel with HQ-61 whenever the situation would have allowed. When a land-based mobile version was added around a decade later, it was designated as HQ-61A, so despite have the A suffix, HQ-61A was actually a later model than HQ-61B. Due to the political turmoil in China, namely, the Cultural Revolution, HQ-61A/B were not completed until 1986, more than two decades later after the project had started, and certification of mass production for HQ-61A/B were granted in 1988.

HQ-61
Because China had not developed any ship-borne SAM system, China decided to first develop a land-based, fixed-site version of HQ-61 SAM, and then progress to the naval version after the development of the land-based version had been matured. The naval version would be based on the expertise gained from the land-based version to reduce costs and risks. The land-based, fixed-site version was designated as HQ-61, while the naval version was designated as HQ-61B. Before 1970, the HQ-61 went through two major redesigns based on the feedback of earlier tests. In September 1970, new problem arose when it was discovered the speed of the missile had dropped drastically after the redesign. Based on the suggestion from staffs of the SAM testing range, the 2nd Electro Mechanical Bureau of Shanghai organized another redesign in 1973, successfully solved problems encountered, including speed reduction and vibration. Meanwhile, new technologies were also adopted, including transistors, gyro accelerometer and measures against salinity and other environmental hazards.

From March 1975 through April 1975, four rounds of prototype of HQ-61 missile with independent closed-loop were test-fired, with satisfactory result. In 1976, tests were conducted on subsystem interfacing, including that of radar seekers and ground equipment, and one of the results was that the seeker had successfully locked on the target, proving the design was sound for the time being. The success convinced the developer to extend the test over the sea and beginning in December 1976, 45-day-long sea trials were conducted on 12 sorties completed by frigates of Chinese navy, and 13 sorties completed by Harbin H-5 for supporting. Various tests were conducted during the sea trial, including test launches, tracking of the parachute targets, engaging parachute targets, guidance accuracy, reliability of the launcher, effects of launching in different sea states, noise and vibration caused by the launch. During the sea trial, two duds and two remotely controlled rounds were fired, and the result was less than satisfactory. The two duds were relatively successful, but the two remotely controlled rounds resulted in complete failure, missing the parachute targets. The unsatisfactory result convinced the developer not to rush to the sea, but instead, to keep a prudent pace on land first to stamp out all the problems before going any further. In 1978, a flight test of HQ-61 was conducted on a SAM test range in western Liaoning. This flight test was a mixture of simulation of mathematical modeling and real equipment, with targets being simulated by simulators. A total of nine ballistic trajectories and more than eighty scenarios were tested over four hundred times, providing valuable data and proving the design so far. The prototypes of HQ-61 were also test-fired against Type 381 parachute targets for further evaluation, but the result was not completely satisfactory: although the C3I system developed for HQ-61 worked fine, the first shot missed while the second shot scored a direct hit. In order to resolve problems revealed during these tests, the system of general designer was established, and during the development of HQ-61 and later models, Mr. Wu Zhongying (吴中英) and Mr. Liang Jincai (梁晋才) had been assigned as the general designers of HQ-61 series missiles. However, when the development of the land-based version of fix-site HQ-61 was completed, its service (only with limited numbers) in Chinese military had never gone beyond the evaluation stage, because the need it intended to fill could be filled with HQ-2, and there were no mass production plans for HQ-61 since resources were allocated on concentrating on the development of HQ-61B, the naval version. Furthermore, the fixed-site version was deemed by the Chinese military as not adequate in mobile warfare on the modern battlefield.

HQ-61B
By the end of 1980, developer was confident enough to move from land to sea, and HQ-61B thus begun its own tests. However, the very first test ended in failure and investigation revealed that the cause of the failure was that the fuse did not activate during the entire test. After rework, the test was moved back to land in the spring next year, but met with two continuous failures again, when the fuse detonated earlier than it should. As a result, in February, 1981, the 2nd Electro Mechanical Bureau of Shanghai concentrated most of its effort on solving the difficulties on fuse, and its staffs came up with three plans to answer the problem: large rework/redesign, intermediate rework/redesign, and minor rework/redesign. After testing samples built according to each plan and comparing result, the intermediate rework/repair plan was adopted, result in a new combined fuse that was reliable. During this time, the 2nd Electro Mechanical Bureau of Shanghai was reorganized as Shanghai Aerospace Bureau, and measures were taken to address the numerous problems encountered in the development of HQ-61B, totaling more than 410. When these problems were solved, the subsequent test on land in November, 1984 was successful, including downing of two Changkong-1 (长空1号) drones.

Meanwhile, the C3I system associated with HQ-61B was also making slow but steady progress. In addition to extra temperature and salinity factors, noise and stability were also challenges of ship-based system, while the space is cramped on board. As a result, developer was forced to adopt new technologies and new means, many of them were first in China. A mono-pulse centimeter wavelength tracking radar was developed for HQ-61B for surveillance / tracking, while a continuous-wave centimeter wavelength illuminating radar was developed for HQ-61B for engagement. Fire control computer of HQ-61B was a newly designed digital computer, incorporating analog – digital and digital – analog conversions. The launching system was hydraulically operated with twin launchers, connecting to ammunition drum below, where additional missile were stored vertically. The control consol of HQ-61B also performs maintenance tests / checks on missiles mounted on the launcher.

From November 1986 through December, 1986, tests were resumed at sea, achieving satisfactory results, including downing five Sea Eagle-1 (海鹰1号) drones and two Changkong-1 drones in a single test. After these successful tests, the HQ-61B entered low-rate production and saw limited service in Chinese military, and the production pickup in November, 1988 when Chinese State Department and the Chinese Central Military Commission certified so. HQ-61B served only in relatively short time with Chinese navy, and it has been converted to air-to-air and anti-radiation versions after it was retired from Chinese service. One of the reasons of its short service time was that as a design originated in the 1960s, it could not adequately meet the modern threats faced by naval ships. For example, the system can only engage a single target at a time and with two launchers on each ship, the maximum number of threat it can face is only two, which is not sufficient enough to defend the ship from saturated attack.

HQ-61A
To improve the land-based air defense for Chinese ground force, Chinese State Department and the Chinese Central Military Commission decided to develop a mobile low-to-medium level surface-to-air missile based on HQ-61B, and named the mobile SAM system as Hongqi-61A (红旗-61甲), or HQ-61A for short. This would lead to HQ-61A being a later model than HQ-61B, which is an earlier model of HQ-61 series, despite have the A suffix. In August, 1979, the 8th Industrial Bureau of Machinery and the artillery corps of the People's Liberation Army Ground Force jointly redefined the requirement of the mobile SAM system, stating that the C2I system used by HQ-61B should be utilized as much as possible to keep the cost down. The primary contractor remains the same, as the 2nd Electro Mechanical Bureau of Shanghai, which would later be reorganized as Shanghai Aerospace Bureau in the early 1980s. The prime subcontractor was the Shanghai Broadcasting Equipment Factory, which was tasked to develop vehicle-based version of C4I system of HQ-61A.

HQ-61A SAM system is consisted of three vehicles: launcher / transporter, radar vehicle, C2I vehicle, all of which are based on the same SX250 6 x 6 cross country truck to simply logistics and reducing operational cost. In November, 1984, two initial trials were completed, proving the design was sound. More intensive testing followed, lasting from April, 1986 through June, 1986, which included the successful continuous downing of three drones, and the missile subsequently entered Chinese service, but it was not until two year later, in November, 1988, did the production pickup its pace, when Chinese State Department and the Chinese Central Military Commission finally gave their certifications to do so. Specifications:
 * Length: 3.99 meter
 * Diameter: 0.286 meter
 * Wingspan: 1.166 meter
 * Weight: 310 kg
 * Speed: Mach 3
 * Range: > 10 km
 * Ceiling: 8 km
 * Kill probability: 64% - 80% (single shot)

HQ-61 ARM (YJ-5)
In addition to SAM versions of HQ-61, an anti radar version is also developed in the 1980s. China was seeking a replacement after the termination of Fenglei-7 anti-radar missile (FL-7), and it was decided to utilize HQ-61 to develop an anti-radiation missile (ARM) to meet the urgent need. Development of most subsystems of FL-7 continued as research projects after the production was shelved, and these subsystems were mated with HQ-61 to create the anti-radar missile needed, and most experience was gained via the reverse engineering attempt of AGM-45 Shrike, and to a much less extend, that of AGM-78 Standard ARM. Samples of both missiles were mainly obtained from down American jets and provided to China by North Vietnam during the Vietnam War, though several unexploded samples launched by American jets failed to detonate were also transferred. HQ-61 ARM is basically a HQ-61 missile equipped with the guidance and control system of FL-7 and thanks to the research development rooted from FL-7, HQ-61ARM was quickly completed. HQ-61 ARM also has a less known name as YJ-5, with YJ is short for Yingji (鹰击), meaning Eagle Strike. Due to the highly classified nature and small number produced, HQ-61 ARM is relatively unknown to the public and its YJ-5 designation is often erroneously identified as an anti-ship or land attack cruise missile, as most of other YJ series produced by China. In reality, it is a totally different missile with a different mission in comparison to other better known Chinese missiles of YJ series.

The first batch of YJ-5/HQ-61 ARM was completed in 1984, and was test-fired by Harbin H-5. The missiles met the original requirements, but also revealed many shortcomings, including poor ECCM capability, narrow frequency band coverage, and not being able to lock on to the target after the targeted radar has been switched off. The second batch was completed in 1986, incorporating improvements to solve these shortcomings. The coverage of frequency band was expanded, and memory circuitry was added to calculate the approximate location of the target after the targeted radar had been switched off. The third and final batch was completed in the early 1990s with a new capability added to counter the frequency-hopping radars, and to a limited degree, phased array radars. Despite these improvements, the Chinese technological and industrial capability at the time was not adequate enough to face modern threats on the battlefields, and only limited number entered Chinese service, with Harbin H-5 modified as the carrier, designated as HD-5. The performance of YJ-5/HQ-61 ARM is better than AGM-45, though not too much, and for this reason, plus the purchase of Kh-31 by China, the missile did not enter mass production, and HD-6, the planned modified Xian H-6 intended as another platform did not materialize as a result, and other planned platforms such as proposed modifications for Shenyang J-8, Xian JH-7 and Nanchang Q-5 were also shelved. After receiving newer ARMs such as Kh-31, YJ-91 and YJ-12 entered Chinese service, the surviving HQ-61 ARMs are believed to have been exhausted in training already.

HQ-61C
HQ-61C is the upgrade of previous version, excluding the ARM. The primary improvement is in the electronics. Fully solid state and highly digitized microelectronics are used to upgrade both the missile itself and the associating C3I system. In addition to simplifying logistics and reducing costs, the upgraded system can also be automatically linked to larger air defense networks, with all information transmitted electronically in real time. Previously, such information could only be transmitted verbally by operators because the older HQ-61 system could not be easily integrated into larger air defense network, and the communication subsystem of the C3I system of HQ-61 was only consisted of wired and wireless vocal communication equipment. Another improvement is the adaptation of new rocket motor which boosted the speed of the missile by a third, from the original Mach 3 of earlier versions of HQ-61 to Mach 4 of HQ-61C. The range is also increased but exactly how much is unknown. Some Chinese enthusiasts have claimed that because of the new rocket motors adopted, the size and the weight of the missile is also reduced slightly, but this has yet to be confirmed by other credible sources.

PL-11
PL-11 is the air-to-air derivative of HQ-61, and it is also developed by the same developer of HQ-61, Shanghai Aerospace Bureau. The first successful flight test of PL-11 was conducted in 1992, and the missile entered Chinese service in the mid-1990s. The latest upgrade of PL-11 was completed in 2002. The first PL-11 was an air-launched HQ-61 armed with a mono-pulse SARH seeker based on Italian Selenia Aspide, and eventually upgraded with an ARH seeker. To meet the airborne requirement, PL-11 is slightly shorter than its SAM counterparts, and has a different set of redesigned control surfaces, which has much smaller wingspans while ensure the same performance. Versions: Specifications: PL-11 did not enter Chinese service in very large numbers because it was only used as a stopgap measure until the more advanced PL-12 became available, and there is no confirmed export either.
 * PL-11: This is the basic version, with HQ-61C armed with the mono-pulse SARH seeker based on Italian Selenia Aspide.
 * PL-11A: PL-11 incorporating inertial guidance so that targets would only need to be illuminated at the final stage of the engagement, as opposed to the entire engagement for PL-11. Depending on the airborne radar, PL-11A can engage two to four targets in the same time it takes for PL-11 to engage a single target.
 * PL-11B: ARH version of PL-11, and the last version of PL-11 family. This is a PL-11A armed with an ARH seeker AMR-1. Also known as PL-11-AMR, named after the ARH seeker AMR-1.
 * Length: 3.89 meter
 * Diameter: 0.286 meter (Some sources claim 0.208 meter)
 * Wingspan: 0.68 meter
 * Weight: 310 kg (Some sources claim 220 kg)
 * Speed: Mach 4
 * Maximum range: 40 – 75 km, depending on the size, speed, and heading of the target

User
🇨🇳 China
 * People's Liberation Army Ground Force
 * People's Liberation Army Air Force
 * People's Liberation Army Navy Air Force