Type 7103 DSRV

The Type 7103 Deep Submergence Rescue Vehicle (DSRV) is a submarine rescue submersible of the People's Liberation Army Navy (PLAN) of the People's Republic of China (PRC).

Origin
Type 7103 DSRV was intended to rescue sailors trapped in submarine lost at the sea, and when the decision was made to develop a DSRV, the project number 7103 was given, and subsequently was also used to indicate the type designation. It was jointly developed by a team that included the 701st Research Institute of China Shipbuilding Industry Corporation, Shanghai Jiaotong University, Harbin Shipbuilding Engineering Institute (HSEI, later reorganized as Harbin Engineering University), Huazhong Institute of Technology (HIT, later reorganized as Huazhong University of Science and Technology), and the same builder of the Osprey class submersibles in Chinese service, Wuchang Shipbuilding Factory (later reorganized to Wuhan Shipbuilding Industry Corporation, Inc.) Type 7103 DSRV is the first manned submersible in China.

Developmental history
In April, 1971, the then 34-year old assistant professor Zhu Jimao (朱继懋,February, 1932 -) of HSEI was named by the 6th Ministry as the chief designer of Type 7103 DSRV. A 1954 Shanghai Jiaotong University graduate, Professor Zhu was in charge of some of the tests of Type 091 submarine, the first Chinese nuclear submarine in the 1960s, and had successfully developed some subsystems used on the SSN, such as the underwater autopilot, reverse thruster controlling system, and resistance measuring system. In his work, Professor Zhu has suggested a new experimental methodology of determining the shape of the submarine that would minimize the drag by based on the theory of wave drag with the peak of the transverse wave that has low Fr value, and this resulted in the successful completion of the water tank used for testing. Due to his past success and achievement, Professor Zhu was assigned as the general designer of Type 7103 DSRV at young age, and he immediately joined his colleagues in a small test facilities on the bank of Lake Tai, sacrificing his personal life, as with the rest of the team. For example, Professor Zhu did not see his daughter for more than a year after she was born. Also in April, 1971, a joint team was set up at Wuhan Shipbuilding Factory, with the 701st Research Institute of China Shipbuilding Industry Corporation as the general design team and HSEI as the deputy general design team.

China had never developed anything similar before and at the beginning, many suggested to take the prudent approach by repeating the common foreign practice of developing four generations submersibles, i.e. 1st, developing an observatory submersible, and then the 2nd, a submersible capable of working underwater, while the 3rd would be a submersible enabling divers to enter and exit underwater. Finally, the 4th generation would be the DSRV capable of performing underwater rescue operations. Professor Zhu felt that China does not have much time and thus could not spent too much time repeating the foreign experience. Instead, China must develop its own way and thus should directly jump into developing the fourth generation DSRV, despite technological difficulties. After consulting with all experts on the team, a scaled-down radio operated remotely controlled model was used in experiments such as mating operations, as opposed to the common practice of building 1:1 scaled model like the way US did it, and the result was tens of millions of Chinese dollars saved, while the time needed was much shortened. Meanwhile, the methodology Professor Zhu developed for Type 7103 DSRV development, titled “Analysis Methodology of Density in the Designs of Deep Diving Submersibles” had since become the standard text for future Chinese submersible designers.

In 1972, another scholar, Mr. Xu Yuru (徐玉如) joined the design team of Type 7103 DSRV. Mr. Xu is also a professor of Harbin Engineering University, and an expert in fluid dynamic, and he was first put in charge of building the scaled model of Type 7103 DSRV for simulation. The team, as well as the entire 7103 project soon ran into difficulties when after three years of experiments, a little progress was made. Some of the team members were reassigned, while others eventually immigrated abroad, but Professor Xu stayed, and believed that there would be success when the correct methodologies were used. After overcame difficulties such as inadequate funding and primitive equipment, as well as his own health problem of having peptic ulcer which resulted in half of his stomach removed in surgery, Professor Xu eventually succeeded, obtaining sixty-seven important fluid dynamic parameters of Type 7103 DSRV, while at the same time, completing the associating planar motion system used in the research, the first of its kind in China.

Construction of Type 7103 DSRV begun in 1976 at Wuhan Shipbuilding Factory, and in January, 1980, it was launched simultaneously with its mother ship, Type 925 Dajiang class submarine rescue ship / salvage ship (ASR/ARS). The 1st stage of sea trials lasted from October, 1984 through August, 1983, with three objectives totaling forty-one trials. Test results from these trials revealed several issues that needs to be addressed, including the need to improve search, guidance and observatory capabilities, the need to improve the reliability of onboard subsystems, particularly that of the reverse thruster and the silver – zinc batteries, and the need to improve the mating system of the skirt. Work immediately begun on solving these problems and it continued around the clock. After the intensive work, the upgraded sample was ready for the next stage of trials.

The 2nd stage of trials begun in 1985, and in May, 1985, sea trials was conducted in South China Sea under the supervision of Professor Xu Yuru, where three operators succeeded in continuously mating with submarines for three times under different sea states. These tests provided the bases on which the mathematic model and other analysis for Type 7103 DSRV were established. Based on the results of these trials, Professor Xu led the team to design the simulation / testing water tank, and also conducted further tests on models in Songhua River. The experience gained was instrumental in successfully developing a four-degree of freedom (DOF) dynamic positioning system needed for Type 7103 DSRV.

Form April, 1986 through June, 1986, tests were conducted for three functions including deep diving, wet and dry rescues. On June 3, 1986, under the command of the general designer Mr. Zhu Jimao, Type 7103 DSRV mated with a submarine and transferred seven crew members of the submarine to DSRV in less than three minutes during a dry rescue mission. This success is dubbed by Chinese as being the 2nd country in the world achieving successful underwater mating between a DSRV and a submarine, after the United States. In the mean time, Type 7103 also completed wet rescue tests, and achieved the deepest diving record of Chinese submarine at the time when it dived to 360 meters below the surface.

Design and structure
Shanghai 3rd Steel Factory (上钢三厂) and Shanghai 8th Steel Factory (上钢八厂) teamed up to jointly develop Type 402 steel used to construct the pressure hull of Type 7103 DSRV, while Type 840-S welding stick of 3Ni – Mn – Cr – Mo series was also developed for welding of the pressure hull. HSEI developed the positioning and integrated display systems for rescue operations in fast flowing ocean currents with low visibility, and the system was the first of its type in China, and subsequently adopted for other applications in Chinese oceanic exploration.

After the conclusion of the first stage of the trials at the sea, it was obvious that operating the DSRV in such complex submarine rescue operations could not be conducted manually alone, but instead, automation was not only needed, but it was also a must. Harbin Engineering University professor Bian Xinqian (边信黔), who was among the first exchange scholars China sent abroad in the early 1980s to study computer systems, PCs in particular, recommended and subsequently lead a team to develop a new computer system for Type 7103 DSRV, because the computer system China had back then was simply too bulky to be fit into Type 7103 DSRV and a brand new system was needed. This was a considerable challenge for Chinese considering that the first miniature computer IBM PC had just appeared several years before and China had nothing similar at the time. Under the leadership of Professor Bian Xinqian, the team succeeded in successfully developing a mini/micro computer system during a short span of time, and adopted the system for use on Type 7103 DSRV. This computer system won national award in 1985, even before the completion of Type 7103 DSRV program.

In November 1987, Type 7103 DSRV was formally handed to PLAN. The success of Type 7103 DSRV is viewed by Chinese as a proof of China joining the ranks of those other countries with advanced submarine rescue technologies. For his contribution of pioneering work in Type 7103 DSRV and submarine rescue technological development in China, the general designer, Zhu Jimao, was awarded the rank of full professor in 1984 by the direct order of the State Council of the People's Republic of China before the completion of the project, and in 1990, he was awarded the national title of Mid-aged and Young Experts with Outstanding Contribution, which was one of twenty-one various awards he received since 1977. Professor Zhu Jimao was later named as the general designer of HR-01 ROUV. In 1990, Type 7103 DSRV won first place in the national science and technological advance award, and the design team of one of the main contractor, the then Naval Engineering Institute of Harbin Engineering University, headed by Zhang Yongyao (张诵尧), was also awarded. The computerized control and command system of Type 7103 was one of the first applications of mini/micro computers in China, and for that pioneering work, this system won the national award in 1985, before the completion of the project.

7103 training submersible
As part of # 7103 project, training submersibles based on Type 7103 DSRV are also built. The training submersible is similar in size, and differs only slightly in external appearance in comparison to Type 7103 DSRV: the tiny conning tower is absent on the training submersible, but instead, an elevated flat-top ridge in the midsection of the training submersible, which is used to simulate the hatches of regular submarines. The training submersible is used to simulate submarines in distraught, and the DSRV would practice docking with the training submersible and transfer crews in training missions. A total of two training submersibles are built and they can be carried by the same mother ships that carry Type 7103 DSRVs.

Service and deployment
Type 7103 DSRV is usually carried by Type 925 Dajiang class submarine rescue / salvage ship (ASR/ARS) of PLAN, which also carries the training submersible. A total of 4 Type 7103 DSRVs are built, but in general, only two are readily available at any given time, while this pair is deployed on ships, the other pair would be at base for maintenance and providing secondary shore-based training. Under emergency situations, all four could be readily available for deployment. While at sea, each Type 925 Dajiang class ASR/ARS would only carry one Type 7103 DSRV, while the slot for the second is used to carry the training submersible for training at sea. During rescue missions, the training submersible would be replaced by a second Type 7103 DSRV.

Although Type 7103 DSRV and its supporting equipment are designed to be air transportable like American Mystic class deep submergence rescue vehicle, China lacks the heavy-lifting cargo airplanes such as Antonov An-124 or C-5 Galaxy for rapid aerial deployment. This air transportable capability is no longer present in the successor of Type 7103 DSRV designed by Harbin Engineering University.

Modernization
Because Type 7103 DSRV is a design of 1970’s, it has rather limited capability to meet the need of a 21st-century environment. The 701st Institute and Wuchang Shipbuilding Factory jointly launched a comprehensive modernization program for all Type 7103 DSRVs, which lasted from 1994  through 1996. The most significant upgrade included the installation of an upgraded 4-DOF positioning system, and the installation of a new integrated command, control and display system. The maximum rescue depth is increased by 20% to 360 meters, while some other additional tasks can also be performed at the maximum diving depth. The size of Type 7103 DSRV is slightly increased after its upgrade in the mid 1990s.

Despite the upgrade, Type 7103 DSRV has nonetheless limited capability due to its inherit old design of 1970’s. The major limitation is that it cannot dock with submarines which are titled at greater angles. Furthermore, during the docking operation, the maximum speed of the oceanic current must not exceed 1.5 kt and the visibility must be greater than 0.5 meter. Realizing that Type 7103 DSRV has reached its potential and there is not much room for any further significant improvements, Harbin Engineering University has developed a successor of Type 7103 DSRV to overcome these shortcomings.

Specifications
The dimension of Type 7103 is slightly increased after the 1994–1996 modernization, though the difference is very minor:
 * Length: 14.88 meter pre modernization, > 15 meter post modernization
 * Width: 2.6 meter
 * Height: 4 meter
 * Speed: 4 kt
 * Displacement: 32 ton pre modernization, > 35 ton post modernization
 * Maximum diving depth: > 600 meter
 * Maximum rescue depth: 300 meter pre modernization, 360 meter post modernization
 * Rescue pressures: 5 bar
 * Crew: 4 (1 or 2 operators, a diver, and a doctor)
 * Propulsion: Silver – Zinc battery powered
 * Maximum number of rescued submariners: 22 in docking operation, 6 to 10 in wet rescue operation