Sus­tain­ing Vin­tage Weapon Sys­tems

The com­pul­sion of sus­tain­ing vin­tage weapon in­ven­tory is not only typ­i­cal in our con­text but so is the case of most coun­tries around the world that have been car­ry­ing on with their vin­tage in­ven­tory

SP's LandForces - - FRONT PAGE - Lt Gen­eral V.K. Sax­ena (Retd)

The com­pul­sion of sus­tain­ing vin­tage weapon in­ven­tory is not only typ­i­cal in our con­text but so is the case of most coun­tries around the world that have been car­ry­ing on with their vin­tage in­ven­tory.

IN THE CON­TEXT OF our Ground Based Air De­fence Weapon Sys­tems (GBADWS) it is quite fash­ion­able to quote the high fig­ures of per­cent­age ob­so­les­cence (97 per cent or there­about) and gen­er­ally de­cry their very old vin­tage, thus com­ing to a quick con­clu­sion that these are/ will be in­ca­pable of coun­ter­ing the con­tem­po­rary, as well as, the fu­tur­is­tic air threat.

Faced with the above com­mon, the air de­fence warriors find them­selves in an un­en­vi­able po­si­tion. On one side, is in­deed the real­ity of the years of vin­tage and ob­so­les­cence of their com­bat means, while on the other, is a grim re­al­i­sa­tion that any new induction must wait long years (7 to 10) be­fore it ac­tu­ally gets op­er­a­tionalised. What does this de­mand? It de­mands that the ex­ist­ing (legacy) in­ven­tory has to be kept op­er­a­tionally rel­e­vant; come what may.

A World­wide Phe­nom­e­non

In­ci­den­tally, the com­pul­sion of sus­tain­ing vin­tage weapon in­ven­tory is not only typ­i­cal of us (though our per­cent­ages of ob­so­les­cence are much higher), coun­tries around the world have been car­ry­ing on with their vin­tage in­ven­tory. A snap­shot: The Rus­sian in­ven­tory of GBADWS still car­ries the weapons. ZSU-37, ZU-23-2, ZSU-57-2 be­sides oth­ers. Out of these, while ZSU-37, a 1943 vin­tage self-pro­pelled (SP) gun got dis­con­tin­ued in 1962 upon the induction of Schilka weapon sys­tem, ZU-23, a 1960 vin­tage light gun is still in ser­vice, hav­ing seen wide­spread use in Libyan Civil War in 2011 and the cur­rent Syr­ian Civil War. Same is also true for ZSU 57-2 the SP anti-air­craft (AA) weapon of 1955 vin­tage. Chi­nese ZPU-1/2/4 2 AA Gun of 1949 vin­tage is still in ser­vice in China and in over 50 coun­tries of the world hav­ing seen action from Korean War to the Syr­ian Civil War. The Pak­istan Army Air De­fence still op­er­ates the 1962 vin­tage Schilka Weapon Sys­tem (ZSU23-4) and the 34-year-old Artemis Gun Sys­tem of Greek ori­gin. Com­pul­sions to sus­te­nance of ob­so­lete and vin­tage in­ven­tory is thus a world­wide phe­nom­e­non. In fact, no cal­i­bre, the world over, has ever been thrown away com­pletely. Swe­den, Italy and Sin­ga­pore boast of their 40mm ma­chines, Rhein­mettal is up and about with its 35mm, Ger­many, Greece and Italy per­fect their 30mms, the Rus­sian block with Poland, Fin­land and Bel­gium are go­ing strong with 23mm and the French, US, Is­rael and Korea with 20mm.

Chal­lenges Galore

What chal­lenges the legacy weapons throw up? The pro­duc­tion lines of the main frame weapon get long closed down by the OEM; hence noth­ing fresh fetches up. In­vari­ably, in yesteryears, the weapons which were bought as whole con­sign­ments, (gen­er­ally on a gov­ern­ment-to­gov­ern­ment agree­ment) hardly ever came with ded­i­cated sim­u­la­tors. With decades of op­er­a­tions and train­ing on war equip­ment it­self, ev­ery sin­gle piece of old weapons goes far beyond its de­signed op­er­a­tional hours/ser­vice life. With the fi­nite spares that come with the orig­i­nal con­sign­ment or the quan­tity that keeps com­ing till such time the pro­duc­tion lines are alive can hardly suf­fice to keep the equip­ment go­ing for decades of ex­tended life. Ef­fects: Af­ter ini­tial years of suf­fi­ciency, the paucity starts show­ing its ugly phase (around the mid-life over­haul) and keeps be­com­ing worse year-on-year, not only di­lut­ing the qual­ity of over­haul but also mak­ing dif­fi­cult, the day-to-day sus­te­nance. Since in yesteryears most legacy weapons came with­out the life-time­buy (LTB) of spares clause. These mea­sures got ap­plied as the sit­u­a­tion be­comes more crit­i­cal and equip­ment sus­te­nance started pos­ing ex­is­ten­tional threat. And fi­nally when only a trickle ar­rives that too in a spo­radic mode from the LTB route, fait ac­com­pli mea­sures start to get ap­plied. What are these? Can­ni­bal­i­sa­tion from a part of in­ven­tory to keep alive the bal­ance. Fore­go­ing the over­haul op­tion and only re­sort­ing to ‘op­ti­mi­sa­tion,’ i.e min­i­mum main­te­nance to keep the equip­ment from be­com­ing EOA. The SAMs pose a to­tally dif­fer­ent set of prob­lems that is, of shelf-life. What to do when the OEM spec­i­fied shelf-life ex­pires. Ob­vi­ously, shelf life ex­ten­sion. How many? One, two, three, af­ter which the is­sue starts be­com­ing crit­i­cal, as the per­ish­able parts sim­ply start to age, the elec­tron­ics com­po­nents start loos­ing their re­li­a­bil­ity and not much can be said on the con­tin­ued ef­fi­cacy and lethal­ity of the war­head ly­ing in pas­sive compact mode for nearly a few decades. Also, with legacy mis­siles, there are huge prob­lems of ref­er­ence stan­dards that need to be ap­plied af­ter so many years of stor­age. Do the orig­i­nal ta­bles ap­ply? Are the tol­er­ances and mar­gins of the orig­i­nal to be kept un­changed or these be mod­i­fied. If the lat­ter, how much lee­way ex­ists, and more im­por­tantly, what is the logic? Not sim­ple by any chance. These are the type of chal­lenges that stare the air de­fence war­rior in the eye. Let us ex­am­ine what can be done.

As re­gards the towed main­frame gun sys­tems, very ‘en­abling up­grades’ are pos­si­ble. What do these prom­ise? Re­moval the vin­tage tar­get lay­ing sys­tems and re­plac­ing it with an elec­troop­ti­cal fire con­trol sys­tem (E-OFCS). This amounts to a ‘com­plete re­vamp’ of the erst­while me­chan­i­cal sights for tar­get lay­ing with the fol­low­ing: A CCD Cam­era (nor­mally with 16/18X, 1/4 CCD de­vice, 1.6-230 FOV and fo­cus range from1 to in­fin­ity). Ther­mal Cam­era (Typ­i­cal 8-10mm band, 20-250 FOV, range in ex­cess of 2 km, cooled). An eye-safe LRF (1-1.2mm band, FOV 2-2.5 MRAD, with ranges in the re­gion of 18-20 km). A built-in fire con­trol com­put­ing de­vice that works out the gun lay­ing data in bear­ing and el­e­va­tion as the tar­get is kept laid at the sight retic­ules. In or­der to in­crease the re­sponse of the gun to the fast ma­noeu­vring air threat, the erst­while me­chan­i­cal or hy­draulic drives of the gun are re­placed with high re­sponse elec­tric drives tak­ing the gun move­ment re­sponse in bear­ing and el­e­va­tion from 8-100 per sec­ond to 60-1,000 per sec­ond with ac­cel­er­a­tion in ex­cess of 1,300 per sec­ond. This re­moves the erst­while slug­gish­ness and makes the gun sharply cut to the ma­noeu­vring threat. An on board si­lent gen­er­a­tor that pow­ers the gun re­duc­ing de­pen­dence on bulky and noisy power sup­ply source. Since the vin­tage ord­nance can­not be retro-mod­i­fied to re­ceive the type of the cut­ting-edge am­mu­ni­tion of today, that has built in fea­tures of re­ceiv­ing roundto-round in­tel­li­gence of in­stant muz­zle ve­loc­ity and re­sul­tant time-of-flight be­sides a pal­letised sub-mu­ni­tion fill­ing with in­tel­li­gent prox­im­ity-fus­ing for max­imis­ing the lethal­ity and ac­cu­racy at the tar­get end, op­ti­mi­sa­tion of the ex­ist­ing am­mu­ni­tion is the way for­ward. In that, the con­ven­tional sin­gle charge pre-frag­mented HE/HE-T and APC rounds are re­placed with rounds car­ry­ing pre­formed frag­mented cubes (PFFC) of tung­sten ma­te­rial cou­pled with prox-

With legacy mis­siles, there are huge prob­lems of ref­er­ence stan­dards that need to be ap­plied af­ter so many years of stor­age

im­ity fus­ing. Ex­pe­ri­ence has it that PFFC fir­ing is about 60-70 per cent more ac­cu­rate that the erst­while am­mu­ni­tion. Also, old vin­tage guns have lim­i­ta­tions up to which, the rate of fire can be ramped up. With mod­i­fi­ca­tion in the buf­fer de­sign and re­duc­ing the length of mov­ing part trail se­quence, it has been pos­si­ble to touch 300-330 RPM jacked from 240 RPM. In self-pro­pelled guns, in ad­di­tion to all the above, the vin­tage ana­logue radars can be re­placed by state-of-the-art dig­i­tal phase ar­ray radars. These sys­tems are not only more compact but also far more ac­cu­rate in tar­get track­ing. Re­place­ment of erst­while fuel guz­zlers gas tur­bine en­gines (GTEs) with fuel-ef­fi­cient dig­i­tal Power Packs is another smart mea­sure that en­hances the power and mo­bil­ity of these old war horses.

Another chal­lenge faced by legacy sys­tems is night blind­ness. This void is slowly get­ting di­luted as Ther­mal im­ager/FLIR / IIR base night sights are get­ting into place mak­ing legacy sys­tems, night ca­pa­ble.

The near ab­sence of spare sup­ply of legacy equip­ment is a ma­jor is­sue. Since the LTB also re­sults is a trickle sup­ply, in­di­geni­sa­tion of spares to the ex­tent pos­si­ble by any means in­clud­ing re­verse en­gi­neer­ing is the way to go. Such an ef­fort is the hope of the users. The chal­lenge is in­deed colos­sal.

SAMs, beyond des­ig­nated/ex­tended shelf lives are a real­ity to be faced. This chal­lenge can be ad­dressed along sev­eral routes: Much shorter ex­ten­sions (yearly) based on de­tailed in­tru­sive test of lots with large sam­ple sizes. Re­fur­bish­ment of per­ished rub­ber parts where available. Re-plough­ing spares by can­ni­bal­is­ing some of the beyond-re­pair lots to keep live in­ven­tory sus­tained. Try­ing to develop ref­er­ence stan­dards through ac­tual field tests of ‘as is’ lots. It is based on years of the above ex­peri- ence, that in RFP today where mis­siles are to be de­vel­oped/pro­cured along with the main­frame weapon, much smaller quan­ti­ties are be­ing ini­tially asked for and bal­ance, spread for a much longer pe­riod.

Some Take­aways

Fi­nally a few ex­pe­ri­ence points: Sim­u­la­tors along with the main equip­ment are a must. Op­er­a­tional hours will be­come more and more ex­pen­sive as the years roll. LTB pro­vi­sion has to be a part of ini­tial ne­go­ti­a­tions not a crises-af­ter­thought. The de­sire to keep it out ini­tially to keep costs low, ul­ti­mately re­sults in pay­ing many times over. Time frame for the OEM to keep spare lines open for an en­vis­aged time sched­ule (plus stretch fac­tor) must get men­tioned /ne­go­ti­ated at the time of PNC/ CNC. It is only at this time the OEM is ‘man­age­able’, not later. In­di­geni­sa­tion ef­fort must start much ear­lier in the day if not ab-ini­tio. In­vent­ing the wheel when move­ment is re­quired is not right. What where MToT is be­ing ne­go­ti­ated: Like all ToTs, it is a mind game. It does not only hap­pen on file but by to­tal hand-hold­ing till com­plete in­di­geni­sa­tion is achieved (co-de­vel­op­ment/co-pro­duc­tion/buy back are key words) The main­tainer must be taken beyond BTP and BTS to the ‘know why’ in spe­cific ar­eas. The in­vari­able ten­dency of the OEM to keep that last bit up the sleeve for a per­pet­ual de­pen­dence has to be fought through. Thus goes the dy­namic of chal­lenges as we en­deav­our to keep alive an old vin­tage and ob­so­lete in­ven­tory be­sides liv­ing the prom­ise of mod­erni­sa­tion in the years to come.

(Top) Up­graded Schilka weapon sys­tem and (above) ZSU-57-2 Soviet self-pro­pelled anti-air­craft gun

PHO­TO­GRAPHS: Anoop Ka­math, Wiki­me­dia

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