Emerg­ing Tech­nolo­gies for Fu­tur­is­tic Sub­marines

Com­modore Mukesh Bhar­gava (Retd)


uN­DER WA­TER NAV­I­GA­TION HAS been the ul­ti­mate dream of all sea­far­ers since time im­memo­rial. But it was not un­til the be­gin­ning of the twen­ti­eth cen­tury that in­ven­tors suc­ceeded in de­vel­op­ing prac­ti­cal sub­marines that could stay un­der­wa­ter for rea­son­able pe­riod to be ef­fec­tive as a war fight­ing ves­sel. With the on­set of World War I, na­tions saw the deadly ef­fec­tive­ness of these un­der­wa­ter craft, as Ger­man U-boats threat­ened to starve bri­tain and forced the united States into war, thus high­light­ing the sig­nif­i­cance of sub­ma­rine op­er­a­tions as a doc­trine for win­ning wars at sea. A gen­er­a­tion later, in World War II, U-boats came back to cre­ate havoc by launch­ing nu­mer­ous at­tacks on the Al­lied Fleets in the At­lantic, while in the Pa­cific, US sub­marines lit­er­ally put Ja­panese fleet out of busi­ness. Then, in the nu­clear age, the atomic sub­ma­rine be­came the most pow­er­ful weapon of war ever cre­ated- the de­ter­rent force that para­dox­i­cally alone can main­tain and sus­tain peace.

Navies across the globe have ac­knowl­edged this steel mon­ster as the most lethal and strate­gic plat­form in naval war­fare. On the one hand, the cur­tail­ment of de­fence funds glob­ally has led to the re­duc­tion of num­ber of ves­sels and on the other hand, the quest for im­prove­ments in per­for­mance, stealth and strike ca­pa­bil­ity, has driven the demand for newer tech­nolo­gies to be de­vel­oped and adopted on board sub­marines to stay ahead in the race for supremacy in the deep oceans. Suc­ceed­ing para­graphs con­tain the nar­ra­tives of the new tech­nolo­gies be­ing de­vel­oped across the globe which would change the ex­ploita­tion pat­tern and op­er­a­tional cy­cle of fu­ture sub­marines.

‘Life-of-Ship’ Re­ac­tor Core. The uS navy is ac­cel­er­at­ing the de­vel­op­ment and con­struc­tion of its new Columbia class SSbns to at­tain the goal of en­gi­neer­ing the most lethal, high-tech and advanced SSBN the world has ever seen. These sub­marines will en­ter ser­vice by 2031 and serve well into the 2080s and be­yond. The new sub­marines are be­ing de­signed for 42 years of ser­vice life thus en­gi­neer­ing a Ôlife-of-shipÕ re­ac­tor core, thus rul­ing out mid-life re­fu­elling. This would en­able US Navy to build just 12 SSbns and still be able to have the same sea pres­ence as the cur­rent fleet of 14 bal­lis­tic mis­sile ohio class sub­marines thereby bring­ing in $40 bil­lion sav­ings in ac­qui­si­tion and life-cy­cle cost for the pro­gramme.

Long Life Large Aper­ture Bow Ar­ray Sonar. Columbia class sub­marines are be­ing de­signed with a se­ries of next-gen­er­a­tion tech­nolo­gies, many of them from the Vir­ginia class at­tack sub­ma­rine. Lev­er­ag­ing ex­ist­ing sys­tems al­lows the Columbia-Class pro­gramme to in­te­grate the most cur­rent tech­nolo­gies and sys­tems while, at the same time, sav­ing the de­vel­op­men­tal costs of be­gin­ning a new ef­fort. The Columbia class will utilise Vir­ginia class’s fly-by-wire joy­stick con­trol sys­tem and large-aper­ture bow ar­ray sonar. A com­puter built-into the shipÕs con­trol sys­tem uses al­go­rithms to main­tain course and depth by send­ing a sig­nal to the rud­der and the stern. The large aper­ture bow ar­ray is wa­ter backed with no dome and very small hy­drophones that are able to last for the life of the ship; the new sub­marines do not have an air-backed ar­ray, pre­vent­ing the need to re­place trans­duc­ers ev­ery 10 years.

Maintenance Free Shafts. The shafts of the new sub­marines are be­ing built to last up to 10 or 12 years in or­der to syn­chro­nise with the ships maintenance sched­ule. ex­ist­ing shafts need in­spec­tion and re­fur­bish­ment ev­ery six to eight years.

Fu­tur­is­tic Hoista­bles. The Columbia class will also use next-gen­er­a­tion com­mu­ni­ca­tions sys­tem, an­ten­nas and mast. The present day periscope is now re­placed with a cam­era mast con­nected to fi­bre-op­tic ca­ble, en­abling crew mem­bers in the sub­ma­rine to see im­ages with­out need­ing to stand be­neath the periscope. This al­lows de­sign­ers to move com­mand and con­trol ar­eas to larger parts of the ship and still have ac­cess to im­ages from the cam­era mast.

Mixed Re­al­ity Ñ Sub­ma­rine De­sign. The con­tem­po­rary sub­ma­rine de­sign­ers use vir­tual re­al­ity that en­ables the de­signer to have a vir­tual walk-through of the sub­ma­rine in an im­mer­sive en­vi­ron­ment and make de­sign, lay­out, main­tain­abil­ity and ac­ces­si­bil­ity im­prove­ments as re­quired. The users can also have a touch and feel of the sub­ma­rine and give rec­om­men­da­tions from op­er­a­tions and ex­ploita­tion view point even be­fore the steel is cut. The re­quire­ments of degut­ting-re-gut­ting of the sub­ma­rine dur­ing ex­ploita­tion can also be catered at the de­sign stage it­self. In fu­ture, one can ex­pect the Vir­tual re­al­ity im­mer­sive en­vi­ron­ment get­ting blended with the real World through Hololens (mi­crosoft) cre­at­ing a mixed re­al­ity ex­pe­ri­ence for sub­ma­rine de­sign­ers.

Stealth, Sen­sors & Acous­tic Su­pe­ri­or­ity. The naval R&D is mak­ing progress in de­vel­op­ing new acous­tics, sen­sors and qui­et­ing tech­nolo­gies to en­sure the uS re­tains its tech­no­log­i­cal edge in the un­der­sea do­main. The in­no­va­tions in­clude qui­et­ing tech­nolo­gies for the en­gine room to make the sub­ma­rine harder to de­tect, by us­ing a new large ver­ti­cal ar­ray and ad­di­tional coat­ing ma­te­ri­als for the hull to at­tain what uS navy calls “Acous­tic Su­pe­ri­or­ity”. The idea with “acous­tic su­pe­ri­or­ity,” is there­fore to en­gi­neer a cir­cum­stance wherein uS sub­marines can op­er­ate un­de­tected in or near en­emy wa­ters or coastline, con­duct re­con­nais­sance or at­tack mis­sions and sense any move­ment or en­emy ac­tiv­i­ties at far­ther ranges than ad­ver­saries can. The acous­tic su­pe­ri­or­ity pro­gramme is fo­cussed on the sen­sor side whereby they are on the cusp of a fourth gen­er­a­tion of un­der­sea tech­nol­ogy based upon a “do­main” per­spec­tive as op­posed to a plat­form ap­proach – look­ing at and as­sess­ing ad­vance­ments in the elec­tro-mag­netic and acous­tic un­der­wa­ter tech­nolo­gies to min­imise plat­for­mÕs own sig­na­ture Ð while hav­ing a bet­ter abil­ity to de­tect an ad­ver­sary sig­na­ture. The “acous­tic su­pe­ri­or­ity” ef­fort is im­mersed in per­form­ing tac­ti­cal as­sess­ments as well as due dili­gence from an aca­demic stand­point to make sure the ser­vice looks at all the threat vec­tors – hy­dro­dy­nam­ics, acous­tics or lasers.

VLF Com­mu­ni­ca­tion. The emerg­ing tech­nolo­gies, how­ever, are heav­ily fo­cused upon sen­si­tive, pas­sive acous­tic sen­sors, which are able to de­tect move­ment and ob­jects of po­ten­tial ad­ver­sary boats and ships at much fur­ther ranges and with a higher-de­gree of fi­delity. Sub­marines are able to use a very low fre­quency ( Vlf) ra­dio to com­mu­ni­cate while at var­i­ous depths be­neath the sur­face. In­dian Navy­has al­ready com­mis­sioned its own Vlf trans­mis­sion sta­tion at INS Kat­tabo­man in col­lab­o­ra­tion with l&T thereby also cre­at­ing nu­clear elec­tro mag­netic pulse (nemP) proof con­trol sta­tion, the first in In­dia.

Un­der­wa­ter De­tec­tion Capabilities. new de­tec­tion tech­niques are emerg­ing that donÕt rely on the noise a sub­ma­rine makes, and may make tra­di­tional manned sub­ma­rine op­er­a­tions far more risky in the fu­ture. These in­clude in­creased use of lower fre­quency ac­tive sonar and non-acous­tic meth­ods of de­tect­ing sub­ma­rine wakes at short ranges. In par­tic­u­lar is the tech­nique of bounc­ing laser light or light-emit­ting­diodes off a sub­ma­rine hull to de­tect its pres­ence. The physics be­hind most of these al­ter­na­tive tech­niques has been known for decades, but was not ex­ploited be­cause com­puter pro­ces­sors were too slow to run

The con­tem­po­rary sub­ma­rine de­sign­ers use vir­tual re­al­ity that en­ables the de­signer to have a vir­tual walk­through of the sub­ma­rine in an im­mer­sive en­vi­ron­ment and make de­sign, lay­out, main­tain­abil­ity and ac­ces­si­bil­ity im­prove­ments as re­quired

the de­tailed mod­els needed to see small changes in the en­vi­ron­ment caused by a quiet sub­ma­rine. To­day, ‘big data’ pro­cess­ing en­ables advanced navies to run so­phis­ti­cated oceano­graphic mod­els in real time to ex­ploit these de­tec­tion tech­niques.

Silent Propul­sion Sys­tem. While the uS is tak­ing gi­ant strides China is not lag­ging be­hind. China’s new sub­ma­rine en­gine is poised to rev­o­lu­tionise un­der­wa­ter war­fare. Chi­naÕs new nu­clear sub­marines will soon use a ‘shaft-less’ rim-driven pump-jet, a rev­o­lu­tion­ary and silent propul­sion sys­tem. A rim-driven pump-jet has a ring-shaped elec­tri­cal mo­tor inside the pump jet shroud, which turns the vane ro­tor (a vane ro­tor has the fan blades at­tached to a ro­tat­ing band built on a cylin­dri­cal in­te­rior, as op­posed to a pro­pel­ler shaft) inside the pump jet cav­ity to cre­ate thrust. The sub­ma­rine pump­jets so far are ‘shrouded pro­pel­lers’, which con­sist of a tubu­lar noz­zle cov­er­ing the pro­pel­ler. By re­mov­ing the shaft of the pro­pel­ler, the re­duc­tion in the num­ber of mov­ing parts de­creases the noise made by the pump-jet, as well as sav­ing hull space. The orig­i­nal equip­ment man­u­fac­tur­ers (oems) also claim that rim driven pump jets are eas­ier to main­tain and have less cav­i­ta­tion mak­ing them even qui­eter.

In­te­grated Elec­tri­cal Propul­sion Sys­tem. The lat­est Chi­nese sub­marines are be­ing de­signed with in­te­grated elec­tri­cal propul­sion sys­tem (IEPS). The Chi­nese vari­ant is the world’s first IEPS to run on a medi­um­volt­age, di­rect-cur­rent sys­tem. IEPS turns all the out­put of the shipÕs en­gine into elec­tric­ity, un­like tra­di­tional propul­sion de­signs, which con­vert en­gine and re­ac­tor out­put into me­chan­i­cal ac­tion to turn the pro­pel­ler shaft. The high elec­tri­cal out­put can be used to power mo­tors for the pro­pel­lers or po­ten­tially high-en­ergy weapons. Ad­di­tion­ally, IEPS has far fewer mov­ing parts, mak­ing them qui­eter and thus ideal for use on sub­marines. The rim-driven pump-jet and IEPS can drastically re­duce the acous­tic sig­na­ture of any SSN. This com­bi­na­tion, if it works, would be a sig­nif­i­cant gain for China’s naval power and Chi­nese may have stolen a march on the Amer­i­cans and Bri­tish, whose Columbia and Dread­nought SSbn have the op­tion for rim-drive pump-jets, but will not en­ter ser­vice un­til 2030. While the sys­tem would be on China’s at­tack sub­ma­rine, Chi­nese SSbns could also use the rim-drive pump­jet to en­hance their stealth and sur­viv­abil­ity and by ex­ten­sion, the cred­i­bil­ity of China’s se­cond strike nu­clear ca­pa­bil­ity. These new sub­ma­rine propul­sion sys­tems may not just power China’s sub­marines of the fu­ture, but give Beijing a true su­per­power’s un­der­wa­ter ar­mada sta­tus.

Air In­de­pen­dent Propul­sion. Amongst the var­i­ous type of air in­de­pen­dent propul­sion (AiP) sys­tems in use on-board con­ven­tional sub­marines, the fuel cell (fC) based Sys­tem is the most sought af­ter and is also the pre­ferred op­tion for P75(I). While all FC AIP have Liq­uid Oxy­gen be­ing stored in cryo­genic state, dif­fer­ent coun­tries have fol­lowed dif­fer­ent means of gen­er­at­ing/stor­ing Hy­dro­gen: Ger­mans use metal hy­drides and are now mov­ing to­wards methanol re­former, Rus­sian use diesel re­former tech­nol­ogy. In­dian DRDO pro­gram is based on us­ing Sodi­umÐboro­hy­dride. The de­vel­op­ment is in advanced stage and the AiP Sys­tem is ex­pected to be avail­able for P75 (I) pro­gramme.


The pace of sub­ma­rine tech­no­log­i­cal de­vel­op­ment glob­ally, have made even the mooreÕs law (the num­ber of tran­sis­tors per square inch on in­te­grated cir­cuits would dou­ble in the com­puter in ap­prox­i­mately two years) re­dun­dant. The race for in­dian ocean un­der-wa­ter Supremacy is on amongst the tech­nol­ogy lead­ers in US, Europe and China. China is de­ter­mined to im­ple­ment its ÔString of Pearl­sÕthe­ory for the in­dian ocean re­gion (IOR). Be­sides cre­at­ing ar­ti­fi­cial is­land in the South China Sea against the op­po­si­tion from Global lead­ers as well as the lit­toral na­tions, it has also started ac­tive pa­trolling of the ior us­ing its SSbn and SSNs and even seek­ing berthing rights at Pak­istan, Sri Lanka and Myan­mar. In the back drop of these de­vel­op­ments, it is im­per­a­tive for In­dian Navy to keep abreast with the lat­est de­vel­op­ments in the field of sub­ma­rine tech­nolo­gies to be able to re­tain that crit­i­cal edge which can make the cru­cial dis­tinc­tion be­tween the vic­tor and the van­quished, as there is no run­ner-up in a war. It would be good for the de­ci­sion mak­ers to be con­scious of the lat­est emerg­ing tech­nol­ogy trends and in­cor­po­rate these re­quire­ments in the fu­ture RFPs.

It is im­per­a­tive for In­dian Navy to keep abreast with the lat­est de­vel­op­ments in the field of sub­ma­rine tech­nolo­gies to be able to re­tain that crit­i­cal edge which can make the cru­cial dis­tinc­tion be­tween the vic­tor and the van­quished, as there is no run­ner-up in a war

The writer is Vice Pres­i­dent, Sub­marines and Un­der­wa­ter Plat­forms, L&T De­fence.

(Top) Artist’s ren­der­ing of the planned Columbia class sub­ma­rine; (above) Vir­tual re­al­ity tech­nol­ogy can trans­form the fu­ture of sub­ma­rine de­sign.

PHOTOGRAPHS: US Naval Sea Sys­tems Com­mand, BAE Sys­tems

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