Emerg­ing Tech­nolo­gies for Sub­marines of the Fu­ture

SP's NavalForces - - FRONT PAGE - COM­MODORE MUKESH BHAR­GAVA (RETD)

“To gaze into the depths of the sea is, in the imag­i­na­tion, like be­hold­ing the vast un­known, and from its most ter­ri­ble point of view. The sub­ma­rine is anal­o­gous to the realm of night and dreams. There also is sleep, un­con­scious­ness, or at least ap­par­ent un­con­scious­ness, of cre­ation.” —Vic­tor Hugo Com­modore Mukesh Bhar­gava (Retd)

eVER SINCE THE TIME of Vic­tor hugo, sub­marines and 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 rea­son­ably long pe­riod to be con­sid­ered ef­fec­tive as a war fight­ing ves­sel. with the on­set of world war I, na­tions saw the deadly ef­fec­tive­ness of th­ese un­der­wa­ter ves­sels, as Ger­man U-boats threat­ened to starve Bri­tain and ul­ti­mately 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, the Ger­man 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. Presently, in the nu­clear age, the nu­clear sub­ma­rine be­came the most pow­er­ful weapon of war ever cre­ated – to serve as the de­ter­rent force that, para­dox­i­cally, alone can main­tain and sus­tain peace in the re­gion.

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 on or­der 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 some of the new tech­nolo­gies be­ing de­vel­oped across the globe which would change the ex­ploita­tion pat­tern and op­er­a­tional cy­cle of sub­marines of the fu­ture.

Mixed Re­al­ity — 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. this would change the con­cept of sub­ma­rine de­sign in fu­ture.

‘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 re­ac­tor core that would last for the ‘life-of-ship’, thus rul­ing out re­quire­ment of mid-life re­fu­elling. this would en­able US navy to build just 12 SSBns and still be able to have the same sea pres­ence/ops-avail­abil­ity as the cur­rent fleet of 14 bal­lis­tic mis­sile Ohio class sub­marines thereby bring­ing in sav­ing of $40 bil­lion in ac­qui­si­tion and life­cy­cle cost for the pro­gramme.

Un­der­wa­ter De­tec­tion Ca­pa­bil­i­ties. new de­tec­tion tech­niques are emerg­ing that do not 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 nona­cous­tic meth­ods of detecting sub­ma­rine wakes at short ranges. In par­tic­u­lar is the tech­nique of bounc­ing laser light or lightemit­ting-diodes 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 not fast enough to run the de­tailed mod­els needed to see small changes in the en­vi­ron­ment caused by a quiet sub­ma­rine. to­day, ‘big data an­a­lyt­ics & pro­cess­ing’ en­ables ad­vanced navies to run so­phis­ti­cated oceano­graphic mod­els in real time to ex­ploit th­ese de­tec­tion tech­niques.

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 Columbi­aClass pro­gramme to in­te­grate the most cur­rent tech­nolo­gies and sys­tems while, at the same time, sav­ing the cost of be­gin­ning a new devel­op­men­tal 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 ship’s 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.

Stealth, Sen­sors and “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 plat­form’s own sig­na­ture – 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 navy has 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.

Fu­tur­is­tic Hoista­bles. the Columbia class will also use next-gen­er­a­tion com­mu­ni­ca­tions sys­tem, an­tenna 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.

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.

Silent Propul­sion Sys­tem. while the US is tak­ing gi­ant strides, the other emerg­ing su­per power - China is not lag­ging be­hind. China’s new sub­ma­rine en­gine is poised to rev­o­lu­tionise un­der­wa­ter war­fare. China’s new nu­clear sub­marines will soon use a ‘shaft-less’ rim-driven pump-jet, a rev­o­lu­tion­ary and silent propul­sion sys­tem. A rim­driven pump-jet has a ring-shaped elec­tri­cal

“To gaze into the depths of the sea is, in the imag­i­na­tion, like be­hold­ing the vast un­known, and from its most ter­ri­ble point of view. the sub­ma­rine is anal­o­gous to the realm of night and dreams. there also is sleep, un­con­scious­ness, or at least ap­par­ent un­con­scious­ness, of cre­ation. there in the aw­ful si­lence and dark­ness, the rude first forms of life, phan­tom-like, de­mo­ni­a­cal, pur­sue their hor­ri­ble in­stincts.” —Vic­tor Hugo

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 ship’s 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 on­board 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 rim­drive pump-jet 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 In­dian Mod’s Project 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 pro­gramme is based on us­ing Sodium–Boro­hy­dride. the de­vel­op­ment is in ad­vanced stage and the AIP Sys­tem is ex­pected to be avail­able for P75(I) pro­gramme. the other emerg­ing op­tion for the AIP for sub­marines is based on Lithium Ion high power bat­ter­ies. this tech­nol­ogy has al­ready been put to sea by the Ja­panese for their So­ryu Class sub­marines. rus­sian also claim to have achieved a break­through in de­vel­op­ing Lithium Ion bat­ter­ies for sub­ma­rine ap­pli­ca­tions.

Con­clu­sion

the pace of sub­ma­rine tech­no­log­i­cal de­vel­op­ment glob­ally, have made even the Moore’s 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. while In­dia has the most am­bi­tious sub­ma­rine build­ing pro­grammes any­where in the world to­day, the de­lay in de­ci­sion mak­ing and the lack of a fo­cused ap­proach at the Mod, has led to In be­ing forced to man­age with a de­pleted sub­ma­rine force level. on the other hand, China is de­ter­mined to im­ple­ment its ‘String of Pearls’ the­ory 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 tech­no­log­i­cal 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 rFPs for pro­cure­ment of fu­ture sub­ma­rine pro­grammes.

(Top) An artist’s ren­der­ing of the planned Columbia class sub­ma­rine; (above) US Navy’s Ohio class bal­lis­tic mis­sile sub­ma­rine.

PHO­TO­GRAPHS: US NAVSEA, US Navy

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