Romeo-class submarine

The Project 633 class (known in the West by its NATO reporting name as the Romeo class) is a class of Soviet diesel-electric submarine, built in the 1950s. The origin of the Romeo class can be traced to the World War II German Type XXI Elektroboot U-boat. At the end of World War II, the Soviets obtained several Type XXIs, from which they were able to obtain certain key technologies. These technologies assisted in the design of the Zulu- and Whiskey-class. Further improvements on the design led to the Romeo class, which was designed by Lazurit Central Design Bureau ("Lazurit" is the Russian word for lazurite).

Only 20 of the Soviet Union's originally intended 56 were completed between October 1957 and the end of December 1961 because of the introduction of the nuclear submarine into the Soviet Navy.

By today's standards Romeo class submarines are considered obsolete, but still have some value as training and surveillance vessels.

Operators of Romeo class submarine
Several navies operate or have operated Romeo class submarines:
 * Russia and the Soviet Union had 20 Romeo class vessels in service. These vessels are no longer used as combat vessels in the Russian Navy, although one or two remain in service as immobile training facilities.
 * China has operated an estimated 84 of the Type-33 submarine (Romeo) during the Cold War. Most have been scrapped, but 31 are still in use for training.
 * North Korea operates 22 Romeo class submarines, that were both locally assembled with Chinese supplied parts and directly imported from China. The 4 Chinese imported units are based on the western coast.
 * Bulgaria operates one Romeo class submarine, which is the last remaining of four boats that were exported from the Soviet Union.
 * Syria has decommissioned the three Romeo class submarines that it imported from the Soviet Union.
 * Egypt operates four of an original eight Romeo class submarines that are upgraded variants of the Chinese design.
 * Algeria has decommissioned its two Soviet Romeo class submarines.

Chinese Romeo class submarines and their derivatives
Under the 1950 Sino-Soviet Friendship and Mutual Assistance Treaty, the Soviets passed to China (and later to North Korea) the documentation necessary to produce Romeo submarines in 1963. The Chinese variant is known as the Type 033 Romeo. A total of 84 Type 033 submarines were built in China from 1962 to 1984, plus several exported to other countries. The Chinese Type 033 incorporated some improvements over the original Romeo, including noise reduction of 20 dB. Sonar on board was also continuously upgraded: the original Soviet sonar was first replaced by domestic Chinese Type 105 sonar, which consequently was replaced by H/SQ2-262A sonar built by No. 613 Factory. Today most of the Type 033 subs have been retired or preserved, with few remaining for training purposes. A total of six Chinese Romeo class submarine was developed:


 * Type 6633: Original Chinese built Romeo, 6 were planned, but only 2 were completed. Originally planned as a Chinese assembled Romeo class, construction program came to a complete stop due to Sino-Soviet split, because former-USSR stopped the delivery of parts. Construction of the 3rd units at Wuhan stopped, and available parts were diverted to complete the first pair, but many parts had to be developed indigenously.  The primary improvement of Type 6633 over the original Soviet boats is the use of domestic Chinese battery, which had slightly superior performance than the original Soviet battery.


 * Type 033: Complete domestic production in China was achieved in 1967, and subsequently renamed as Type 033. However, experience from deployment of completed boats in warmer climate proved that the original Soviet refrigeration and air conditioning system designed for subarctic and arctic area was woefully inadequate for subtropical and tropical regions, so redesigns were needed to improve refrigeration and air conditioning systems, and all boats to be stationed in tropical and subtropical regions went through such refit.  In September 1969, brand new construction of Type 033 with improved air conditioning and refrigeration capability begun at Huangpu Shipyard in Guangzhou, were eventually, 13 units were completed.


 * ES5A: Upgrade Type 033, and improvements are mainly in the replacement of equipment of Soviet origin with domestic Chinese system, which includes: QZHA―10 (Type 779) attack periscope and QDYA―10 (Type 778) general purpose periscope. Addition of H/SQG-2 ranging sonar, Type 063 communication systems, and countermeasure systems. Domestic Chinese Type 801 sonar replaced the original Soviet MARS-24 sonar.  The only difference between Type 801 sonar and its predecessor MARS-24 sonar is that there are 24 transducer elements for Type 801 as opposed to 12 in the original MARS 24, so the Chinese sonar had better accuracy. Domestic Chinese reconnaissance sonar H/SQZ-D sonar (with transducer designated as Type 105) replaced the original Soviet system, with performance of SQZ-D is almost identical to the original Soviet sonar it was developed from, except the sector of scan, which is increased by 15 degrees. Additional noise reduction measure also adopted.  This is the type China originally sold to Egypt in the 1980s.


 * Type 033G: Development of ES5A, with the incorporation of capability to launching acoustic homing torpedo, with analog computers added to achieve automation in order to speed up the calculation of torpedo fire control calculations that was previously requiring manual work. All Chinese Romeos have been converted to this standard. The NATO reporting name for this type is rumored to Wuhan class.


 * Type 033G1: A single Type 033G was modified to carry 6 YJ-1 (CSS-N-4) SSM, this variant is called Type 033G1, with rumored NATO reporting name as Wuhan A. The missile had to be fired while the boat is surfaced, with the total exposure on the surface less than 7 minutes. The most significant improvement, however, is the reduction of noise level by 12 dB.


 * ES5B: Development of Type 033G, primary intended for export. This is an upgrade package for Romeo submarine users. The primary improvement of this class is the ability to launching wire guided torpedoes and anti-ship missiles (AShM) while submerged. Program originally begun in the mid-1980s, and Egypt is reported to be the only customer when China won a contract to upgrade its Romeo-class submarine fleet, including both the Soviet built and Chinese built units.  This is the last type of Chinese Romeo class submarine, with noise reduction of 20dB to 140 dB in comparison to the 160 dB of the original Soviet Project 633 former-USSR delivered to China (in kits forms).

In the 1970s, China's Wuhan Ship Development and Design Institute (701 Institute) built an improved submarine based on the Type 033 hull, named Type 035 Ming. The 035 Ming had an improved diesel-electric engine, improved hull design with less hydrodynamic resistance, better underwater speed, and a more capable sonar, the H/SQZ-262 built by No. 613 Factory replacing the Type 105 sonar used on Type 033 submarines. A total of 21 Type 035 Ming sub were built between 1971 and 2000. There are at least 4 known variants of the Type 035 Ming, ES5C, ES5D, ES5E, and ES5F. The last variant, ES5F, is sometimes referred to as the Type 035G, and upgrades included H/SQZ-262C sonar built by No. 613 Factory replacing the original H/SQZ-262 used on the original Type 035 submarines. Today, 17 Type 035 Ming subs remain in service with the People's Liberation Army Navy (PLAN). One Type 035 Ming is said to have been modified as a test-bed for new Air Independent Propulsion (AIP) system.


 * Type 035: First unit of the Ming class submarine, with construction of 2 units begun simultaneously in October 1969 in Wuchang Shipyard and Jiangnan Shipyard. The general designer was Mr. Wei Xumin (魏绪民).  The most significant difference between Type 035 Ming class and Type 033 Wuhan class is that the former is driven by a single shaft instead of twin shafts of the latter. Trials completed in October 1974 and this first unit (original pennant number 162, but later changed to 232) built at Jiangnan Shipyard entered Chinese service in the following month.


 * Type 035A: The second unit of the Ming class submarine with pennant number 342 was built at Wuchang Shipyard, and many problems were discovered during its trials. As a result, the Chinese navy ordered 701st Institute to perform a major redesign, which not only solved the problem, but also increased the top speed by 40% to 18.3 kt. The redesigned boat was completed in June 1980, and finally entered Chinese service on December 24, 1982, with a new designation of Type 035A. In December 1983, decision was made to stop the production of new Type 033 class boat and replace it with Type 035A.  After the completion of the first Type 035A in 1982, the production of Type 035 briefly halted, until 1987, when the production restarted again and 3 more units were completed before the production ended in 1990.


 * ES5C: Export version of Type 035/035A, with updated fire control system to launch acoustic homing torpedoes. There is no known export, but the design was used to upgrade Type 035/035A fleet.


 * ES5D: further development of ES5C for export, with capability to launch AShM while submerged added. As with its predecessor ES5C, there's no known export but the design was used to upgrade Type 035/035A fleet.


 * Type 035G: Program begun in 1985, and the first unit with pennant number 356 was lunched in 1989, entering service in December 1990, and state certification received in 1993. This is the first Type 035 series to have anti-submarine (ASW) capability. The primary weaponry for Type 035G is Yu-3 torpedo, and French sonar DUUX-5 and its Chinese built version were used on later units, 12 of which were completed between 1990 to 1999.  The last unit with pennant number 308 was lengthened by 2 meters to add a section for AIP tests.


 * ES5E: Export version developed from Type 035G, with ability to launch wire-guided torpedoes added, but there is no known export.


 * Type 035ET: French sonar system and its equivalent Chinese version on ES5E export version of Ming was expensive, so a cheaper alternative was developed, using Italian sonar systems, the JP-64 active sonar and Velox passive sonar of Toti-class submarine. However, this failed to attract any buyers and the unit went into Chinese service instead.


 * ES5F: Export version with integrated sonar system that integrates previously separated active, passive ranging, flank (and towed upon customer's request) sonar into one.


 * Type 035B: First batch of 4 completed between 2000 through 2003, and additional order followed sometimes later. Conning tower and certain portion of hull was redesigned, with new structure similar to that of Type 039 submarine.  This type was capable of launching land attack cruise missile from torpedo tubes.