Invincible-class submarine

The design of the Type-218SG was jointly created by Singapore's Defence Science and Technology Agency (DSTA), ThyssenKrupp Marine Systems (TKMS) and the Republic of Singapore Navy (RSN). The design of the submarines is a highly customised one - conceived to fulfill specific naval requirements of the RSN - including naval operations in littoral waters, guarding sea lines of communication (SLOC), intelligence-gathering (ISTAR) and special operations.[12] The design is believed to be based on the Type 214 export-centric submarine, with design inferences from the Type 212 submarine - both of which were designed by TKMS.[13] The design of the Type 218SG is also believed to have been influenced by the Type 216 submarine concept.[14]

The Type 218SG has a length of 70 metres (229 ft 8 in) and a beam of 6.3 metres (20 ft 8 in), with an overall displacement of about 2,000 t when surfaced and 2,200 t while submerged. It has an estimated speed of about 10 knots (19 km/h; 12 mph) while surfaced and 15 knots (28 km/h; 17 mph) while submerged.[15]

The Type 218SG features several unique characteristics, such as :-

• An "X-shaped" rudder configuration similar to that on the Type 212 submarines and the Dakar-class submarine of the Israeli Navy, for effective maneuverability in Singapore's shallow littoral waters and the South China Sea - as opposed to the Type 214's cruciform rudder configuration.[16]
• A fuel-cell powered air independent propulsion (AIP) module, which allows it to remain submerged for about 50% longer than the Archer-class submarines; several estimates put the Type 218SG's underwater endurance at about 28–42 days (4-6 weeks), without snorkelling.[17]
• A "Horizontal Multi-Purpose Airlock" (HMPL) - which can be utilized to launch torpedoes, special operations forces, divers and submarine-launched cruise missiles (SLCM); the submarines also come with an option to integrate a "Vertical Multi-Purpose Airlock" (VMPL), for launching missiles vertically.[18]
• Use of extensive ergonomical factors - such as air conditioning, enlarged living quarters, additional showering facilities, separate bunk beds, toilet cubicles, additional storage space and equipment unique to the physiques of the RSN's sailors.[19]
• Extensive features of automation - such as a "Combat Management System" (CMS) jointly developed by Atlas Elektronik and ST Electronics and data analytics/decision-support engines developed by the DSTA - which allows the crew to operate the submarine on three 4-hour shifts (instead of two 6-hour shifts), thus allowing greater periods of rest during protracted underwater deployments.[20] The high-level of automation also reduces the crew complement to just 28 (fewer than other contemporary conventional submarines).[21]
• Utility of specific materials accustomed to Singapore's tropical climate and saline waters.[22]
• A higher "payload-carrying" capacity and greater firepower than the Challenger-class and Archer-class submarines, owing to its larger size.[23]

Current details about the Type 218SG's armament are scant; however, it is understood that the submarine features six 533-millimetre (21.0 in) and two 650mm (25.6 inch) forward-firing torpedo tubes - which may be used for firing heavyweight torpedoes, anti-ship missiles, anti-aircraft missile and for laying naval mines.[24]

The Type 218SG is reported to have a greater ordnance payload (and essentially greater firepower) than the RSN's previous submarines, owing to its much larger size.[25]

Details about the Type 218SG's sensors and automation are also scant; however, it is understood the submarines are equipped with a "Combat Management System" (CMS) jointly developed by German-based Atlas Elektronik and Singapore-based ST Electronics, along with data analytics and decision support engines developed by the DSTA.[26] The high levels of sophisticated automation and decision-making systems allows the submarines to run on three 8-hour shifts (instead of two 12-hour shifts), thus allowing the crew more rest to endure prolonged underwater missions.[27]

Given its sophisticated equipment, each submarine is manned by only twenty-eight sailors - a number similar to the RSN's other submarines, but fewer than other contemporary conventional submarines.[28]

In November 2013, Singapore's Ministry of Defense (MINDEF) selected the Type 218SG design, offered by TKMS - as a replacement to the RSN's existing submarine fleet, siding an offer of three conventionally-powered submarines (presumably the Scorpène-class submarine) from French-based naval conglomerate Direction des Constructions Navales (now Naval Group).[29] On 29 November, 2013 - MINDEF officially contracted TKMS to supply two Type 218SG submarines, along with a training and logistics package - at an estimated cost of USD $1.36 billion.[30] The order for the two submarines bore noteworthy significance as the RSN's first-ever order for custom-built submarines; the service had previously relied on the acquisitions of the second-hand Challenger-class and the Archer-class submarines, from Sweden.[31] The purchase of the two submarines was officially announced on 2 December.[32] According to the terms of the contract, the two submarines were to be delivered by 2020-2021.[33]

On 16 May, 2017 - Singapore's defense minister Ng Eng Hen announced that RSN had placed an additional order for two more Type 218SG submarines, with additional arrangements of logistics and crew-training - bringing the total number of its ordered submarines to four.[34] According to the terms of the contract, the two additional submarines were to be delivered by 2024-2025.[35]

In December 2021, German magazine Der Spiegel reported that the outgoing-Merkel government had sanctioned a series of last-minute arms deals, including the export of an additional Type 218SG to Singapore.[36] However, neither the RSN nor TKMS have officially confirmed any such sale.[37][38]

The construction of the first submarine was initiated in 2014, with a "steel cutting" ceremony at TKMS' shipyard in Kiel.[39] The first submarine, christened as the Invincible, was launched in an elaborate ceremony on 18 February, 2019 - with defense minister Ng Eng Hen and representatives of the RSN in attendance.[40] During the ceremony, Ng revealed the names of the other three submarines, namely - Impeccable, Illustrious and Inimitable.[41] Invincible began its sea trials in September 2020, with its planned delivery date scheduled for 2020.[42]

The construction of the second contracted batch was initiated in January 2018, with a "steel-cutting" ceremony at TKMS' shipyard in Kiel, with representatives from TKMS and the DSTA in attendance.[43][44]

In June 2020, Ng revealed that the delivery of Invincible had been postponed to 2022, owing to restrictions caused by the COVID-19 pandemic.[45]