In the late 1950s, No.123 Manufacturing Plant began its own large caliber multiple rocket launcher (MRL) development. This project, like many other military projects was severely disrupted in the 1960s during the Cultural Revolution. It was not until 1978 that major development efforts resumed on the project. In 1984, the plant finally rolled out the 273mm caliber MRL and designated as the Type 83 273mm MRL.
The launcher assembly carries 4 rockets, and is mounted on a Type 60 artillery tractor for mobility. The rockets are free-flight, spin-and-fin stabilized rockets, and do not have guidance systems. As a result, the Type 83’s accuracy especially in term of directional (azimuth) dispersion is much lower than other projectile weapon systems such as traditional tube artillery guns. Rocket system accuracy had always been a major weakness and technical bottleneck. Thus, this was the main area where the designers concentrated their development efforts.
The rocket of the 273mm MRL has a range of 40km with a 138kg warhead. In pursuing specifications set out for the system, the designers had adopted a series of rocket design features. These features included:
Attempts at controlling the rocket's rotation velocity and its directional state at the precise moment departs from launch rail;
Anhancement of the rocket body's mechanical precision characteristics through better quality manufacturing process;
Improvement of its internal ballistic performance.
As for the launch platform, improvements were made to its structural design. These included reinforcing the launcher structural members to increase rigidity, and reducing launcher interference with the rocket body's initial flight. However, despite all these measures the overall system performance was not satisfactory with regard to accuracy, and in tests did not demonstrate an acceptable level of performance.
Throughout various experiments on the system, the rocket's body exhibited signs of unstable flight and inconsistent dispersion. This made prediction of its flight path extreme difficult. In one trial test an accident occurred. A rocket had exploded within the launcher frame, causing all other rockets to explode simultaneously — An undocumented incident just short of a total disaster. This incident had a great impact on the system's development and nearly jeopardized the existence of the whole project. During the 1980s, military funding was so scarce that a single mishap could have proved one too many.
The 273mm system had to contend with an extended range 122mm 40 barrel MRL from No.5137 Manufacturing Plant. The improved 122mm system, which later become the Type 90 MRL, also has a 40km range and it was in early development during the same time. However, despite much debate, work did continue based on the argument that the PLA in need of large caliber rocket artillery system for fire support and to compensate the lack of short-range tactical ground-to-ground missiles. In addition, the 273mm rockets have much more growth potential for range, payload and warhead types than the smaller 122mm system.
Due to the non-satisfactory test results, a lengthy investigation identified two major problems with the system:
(a) Range accuracy Ex/x = 1/33.7 (2.9% of range) during high temperature environment of + 50° C is worse than at standard temperature. Not only so, it is much lower than that of low temperature at -40° C, where its accuracy is Ex/x = 1/83.8 (1.1% of range, nominal for fin-and-spin stabilized rockets). Such condition demonstrated unacceptable abnormality ballistic performance.
(b) Data from a high-speed range camera in one of trail, shown the active flight phase of the four rockets, that is, an in-flight period when the main rocket is still functioning, the rockets from the most left and most right hand side of the launcher crossed each other’s path in-flight. Again, this is an unusual abnormality, and an indication of grossly unacceptable performance in azimuth dispersion.
The designers reckoned these two abnormalities should be treated together as one issue. Regarding the problems with low accuracy at high temperature and trajectory path crossing, investigation centered on the launcher rather than the rocket. They had discovered that, after the rocket's ignition, it completely left the launch rail and the stabilizer apparatus of the rectangular frame launcher had shown lateral vibration. This explained the path crossing of the rockets. And because vibration from the launch frame on both sides of the launcher was greater than those two in the middle, path crossing was more apparent. Later, researchers found out that movement of the stabilizer apparatus of the launcher was due to its frame structure design. During firing, gases from each launch frame producing a lateral force which then interacted with each adjoining structural components to rock the whole launch platform. This problem was exacerbated by gas pressure from the rocket's spin motor and main motor where their force vectors were in opposition. Further analysis also suggested this was also the cause for low accuracy under high temperature environments.
Based on analysis data modifications were drawn up to solve the problems. They included:
a) Redesign of the launcher from a exposed frame and rail to a enclosed case type design. This resulted in the dramatic reduction of lateral forces from rocket motor gases on lateral components of the launcher, and diverted the forces downward and away from the launcher.
b) Reduction of the spin motor apparatus's width, thus reducing torque from jetting gases;
c) Reducing the gap between the launcher casing and rocket body so vibration sources were minimized while the rocket being propelled out of the launcher and while still on the launch rail;
d) Improved quality control during manufacturing, which improved the launcher's vibration damping characteristics by increasing stiffness of the stabilizing apparatus and lateral locking system.
After these improvements the system finally achieved range dispersion of 1/134 (0.7%) and lateral dispersion of 1/83 (1.2%), performance as good as or better than other spin-and-fin stabilized rockets of the day. This then met the 'Combat Accuracy Criteria' for artillery weaponry set by the People’s Liberation Army.
在这些改进之后系统最后达到了1/134（0.7%）射程散布 和达到了1/83（1.2%）横向散布，性能优于当时其它的旋转-和-翼稳定火箭。这于是符合“战斗精度标准”（Combat Accuracy Criteria）用于人民解放军规定的火炮武器。
The Type 83 MRL is currently in limited service with the PLA.
Although the Type 83 MRL experienced a long development and did not enter service in large numbers with the PLA, the project benefited No.123 manufacturing plant in that the staff accumulating much needed experience and data for later designs. And the decision to continue its development proved to be a right one. Succeeding the Type 83 is the Type WM-80, an eight-rocket launcher configuration mounted on a high mobility 8X8 truck. Due to the application of a high performance composite propellant the rocket is capable a range of exceeding 80km with a CEP of 800 meters or approximately 1% of the total range. In addition, the development of a simplified guidance system was mentioned in an early brochure of the WM-80.
The WM-80 rockets can be armed with a range of warheads. Its HE warhead has a blast radius of 70 meters and a single warhead can produce as many as 16800 fragments. The anti-tank cluster warhead has 380 bomblets that each can penetrate 80 to 100mm of top armor. In trials it proved to be a very effective weapon against armor columns and against armored personnel carriers in particular. Other warheads available include incendiary and an fuel-air explosive warhead which potentially can have a blast effect three to five times more powerful than HE equivalent.
The crew compartment of the launcher vehicle houses an advanced fire control unit. Aiming and firing process are fully automated. On receiving a firing order, data from GPS and C3I computers is feed into the fire control computer by the operator. The computer then calculates an optimal firing solution, also taking into consideration the weather, terrain conditions, and the ammo type used. The launcher then automatically elevated into firing position. It will fire the rockets in single shots or full automatic salvo mode depending on the selection made by the operator. A launcher vehicle crew consists of five crew members: a commanding officer, a driver, a mechanical engineer/gunner and two loaders. Usually all members of the crew help out with the reload.
The former Soviet republic of Armenia remain the only user of the WM-80 MRL.
According to Jane's Missile and Rocket, eight of such systems were sold to Armenia in 1999.