An Analysis of the Utility of Depleted Uranium in Kinetic Energy Penetrators 187

1ICBUWOverstatingtheCase:ananalysisoftheutilityofdepleteduraniuminkineticenergypenetratorswww.bandepleteduranium.org

Overstatingthecase:ananalysisoftheutilityofdepleteduraniuminkineticenergypenetratorsDavidCullen,Researcher,ICBUW

ExecutiveSummaryIntroductionInspiteoflongstandingconcernsovertheirtoxicandradioactiveproperties,depleteduranium(DU)weaponsareretainedbyaround20countriesworldwide,primarilyaskineticenergyweapons.GovernmentsthatuseDUasapenetratormaterialoftendefendthischoicebystatingthatitsabilitytopenetratearmourissignificantlygreaterthanalternativematerials.ICBUW,andothers,havequestionedthelegalityofDUweapons,butinthepastthisdebatehasgenerallybeenrestrictedtothehumanitarianandenvironmentaleffectsofDU,ratherthanthemilitaryutilityofDUweapons.Thispaperisintendedtoaddresstheothersideofthedebate,tocriticallyassessandtogivesomecontexttoclaimsaboutthemilitaryutilityofweaponscontainingDU.WhileDUweaponsdoconfersomemilitaryadvantage,thisadvantagecanalsobegainedthroughothermeans:DUdoesnotthereforeconferauniquemilitaryadvantage.Thus,greateremphasisshouldbeplacedonhumanitarianandenvironmentalconcernswhenexaminingDUsacceptability.

Howeffectiveisdepleteduraniumatpiercingarmour?ThereasonthatDUisconsideredtobesoeffectiveasapenetratormaterialisthatitcombineshighstrengthanddensitywithatypeofdeformationonimpactknownas'adiabaticsheer'.Whileotherpenetratormaterials(chieflydifferentalloysoftungsten)areofacomparabledensitytoDU,theyexhibitdifferentdeformationandfracturebehaviours.ItisdifficulttofindinformationinthepublicdomainabouttheeffectivenessofDUandinformationthatmakesanexactcomparisonwithothermaterialsisevenmoredifficulttoaccess.However,internalUKgovernmentdocumentsciteanimprovementofabout15%inperformance.AUSgovernmentdocumentsuggeststhatDUofferedanaverageofa52%increaseinpenetrationabovethatofthetungstenalloys.Thesefigureswillnotnecessarilyholdtrueformoderntungstenalloys,orindeedmoderntypesofarmour.Nevertheless,itseemsreasonabletotreatthemasindicativeandconcludethatonastrictmaterialtomaterialcomparison,DUisbetteratpenetratingarmourthanpresentlyavailablealternatives.HoweveritseemslikelythatDU'sadvantagesasamaterialwillbematchedatsomestagebynewcompounds.A2009reviewofalternativematerialsbystafffromtheUSArmyResearchLaboratoryidentifiednanocrystallinetungstenandbulkmetallicglasses(BMG)asshowingpromiseinkeyareas.OthervariablesdeterminingeffectivenessofkineticenergyroundsPenetratormaterialisonlyoneamongmanyvariableswhichdeterminetheeffectivenessofakineticenergyround.AlthoughDUappearstobethemosteffectivematerial,itisquitepossibletoachievesimilarimprovementsinperformancebyothermeans.Othersignificantvariablesthatcanbeadjustedtoincreasetheeffectivenessofarmourpiercingroundsincludethedimensionsandshapeofthepenetrator.Reducingtheweightorotherperformanceimprovingchangestothesabotcanincreasevelocity,ascanmodificationstothebarrelorimprovementstotheexplosivecharge.


Itappearsthatmodificationstotheround,gunorotherfactors,whichareunconnectedtothechoiceofpenetratormaterial,willoftengivemoresignificantimprovementstoperformancethanchangingpenetratormaterial.WiderdeterminantsoftankwarfareeffectivenessTheantiarmourcapabilityoftanksisdependentonnumerousvariablesbesidesthebasicengineeringcharacteristicsoftheammunitionandgun.Theaccuracyofashot,thespeedatwhichitcanbefiredinresponsetosightinganenemyandtherateoffirecanallplayacriticalroleintankontankconfrontations.Few,ifany,ofthecriteriawhichcontributetotheantiarmourcapabilityoftanksaresosignificantthatanycomparativedisadvantagesinthatfieldcannotbeoffsetbygainsinanother.Certainlythisisnotthecasewhenselectingpenetratormaterial.

Thebestmaterialforthejob?AhistoricalcasestudyofthedevelopmentoftheBritishCHARMroundsandChallenger1tankWhileasimpleconceptionofammunitiondevelopmentmightstatethatthemosteffectivematerialshouldalwaysbechosen,inreality,procurementanddevelopmentdecisionsaremorecomplicated.ThisiswellillustratedbythecasestudyoftheBritishChallenger1tankandtheDUroundsdevelopedforit.Antiarmourtankammunitionisdesignedtodefeatspecificarmourconfigurations.Itisjudgedagainstitsabilitytodefeatarangeofarmourfieldedbypotentialenemiesandonpredictionsoffutureenemyarmourdevelopments.Inthelate1970s,effortstodevelopacommonUS,UKandGermantankgunfailedandtheUKplannedtodevelopanewtankonitsownwitha120mmrifledgun.However,duetoacombinationofexternalcircumstances,itwasdecidedthattheUKwouldpurchaseaderivativeoftheChieftaintank,tobeknownasChallenger1.ADUroundandanewhighpressuregunwereplannedfollowingprojectionsofthetypeofarmourexpectedinthesuccessortotheSovietT80tank,butthegunwouldstillbecompatiblewiththeChieftainammunitionalreadyinservice.UKDUammunitionwasdevelopedbecauseitwasdeemednecessaryfordefeatingaparticulartypeofarmourandcircumstanceshadlimitedthepossibilitiesforadjustingothercharacteristicsoftheweaponssystemwithoutaconsiderableinvestmentoftimeandmoney.ConsequencesforpresentdayUKtankammunitionProblemswiththeChallenger1tanknecessitatedanupgradetothewholeUKtankfleet.Theupdatedtank,knownastheChallenger2,featuredthehighpressuregun,andahighpressureDUround,knownasCHARM3.Thisroundfinallybecameavailablein1999andremainstheUKsmainantiarmourtankammunition.Ratherthanthebrandnewtankenvisagedbymilitaryplannersintheearly70s,theUKisfieldingatankwithagunthatistheresultofevolutionaryadaptationsfromtheChieftain,wherebackwardscompatibility

hasbeenaconsiderationateachstage.Asaresult,designoftheCHARM3roundisdeterminedinpartbydecisionstakenforatankwhichfirstcameintoservicein1965.ThelimitationsofthisroundandthelackofanexportmarkethavepreventedanyfurtherdevelopmentofUKarmourpiercingammunition.LessonsfromtheCHARMcasestudyRatherthanstartingwithablankslateandchoosingthebestmaterialforthejob,ammunitionandprocurementdecisionsaretakenwithinawiderpoliticalandeconomiccontext,whichmaybeconsiderablymoreimportantindeterminingroundcharacteristics.Sincearound2002,UKplannershaverecognisedthatforreasonsofcostandcompatibility,futureBritish


tankammunitionshouldbecompatiblewithotherNATOcountries.However,aplannedimprovementinvolvingnonDUammunition,whichhasapparentlyproventobemoreeffectivethanCHARM3ammunition,hasnotbeenimplementedforreasonsofcost.TheUKsswitchtoDUammunitionallowedthemaoneoffincreaseinpenetration,meaningthatotherprocurementdecisionscouldbetakenforreasonsofbackwardscompatibilityandtosupporttheBritishdefenceindustry,ratherthanmaximisingeffectiveness.However,inthelongrun,thishasnotpreventedtheroundfrombecominglesseffectivethanthenonDUsystemusedbyGermany.ConclusionThefactorsaffectingammunitiondesignandpenetratormaterialchoicearefarremovedfromasimplecaseofchoosingtheammunitionwiththegreatestpossiblemilitaryutility.Althoughstraightforwardengineeringprincipleswillinformthedecision,widerconsiderationsmaybemuchmoresignificant.ItistechnicallypossibletodesignweaponsystemsthatareequallyaseffectiveasDUusingalternativematerials.ThisisparticularlytrueinthepostColdWarerawhenthearmsracebetweendifferentarmoursandpenetratorshaslargelyceased.Allthatisrequiredisthepoliticalwillforchangewithinuserstates.AlthoughDUmay,onconsiderationofpenetratormaterialalone,bebetteratpenetratingarmour,thisadvantageisnotsogreatthatotheradaptationscannotbesubstituted.WhenconsideredinlightofthenumerousdisadvantagesofusingDU,ICBUWbelievestheperceivedbenefitswelloutweighthecosts.TherearesomeindicationsthatthispointofviewisspreadingfromthemanycountriesthathaveneversoughttouseDUweapons,tosomeofthestateswhichwerepreviouslythemostenthusiastic,withrecentreportsthattheUSisplanningtodevelopanonDUsuccessortoitscurrent120mmDUround.WhileDUmayatpresentbethemosteffectivepenetratormaterialinastrictmaterialtomaterialcomparison,thisdoesnotmeanthatDUammunitionissomilitarilyusefulthatalternativescannotbefound,givensufficientresourcesandpoliticalwill.InlightofthenumerousproblemsregardingDUasamaterial,thecaseforuserstatestoabandontheseweaponsisunanswerable.


IntroductionInspiteoflongstandingconcernsovertheirtoxicandradioactiveproperties,depleteduranium(DU)weaponsareretainedbyaround20countriesworldwide,primarilyaskineticenergyweaponsusingalongdartorpenetratorforpiercingarmour.GovernmentsthatuseDUasapenetratormaterialoftendefendthischoicebystatingthatitsabilitytopenetratearmourissignificantlygreaterthanalternativematerials.Underinternationalhumanitarianlaw,theimpactofweaponsonhumanhealthandtheenvironmentmustbebalancedagainstitsmilitaryutilityoreffectiveness.Iftheweaponcausesdisproportionateharmtociviliansortheenvironmentitisnotlegal.DUhaslongbeenasuspectedcauseofhealthproblemsinthecountrieswhereithasbeendeployed.Whilethereisstilldebateabouttheextentoftheriskposedbytheseweapons,therecanbenodoubtaboutthewidespreadconcernsabouttheireffects,theenvironmentalcontaminationthatisleftbehind,andthedifficultiesthisposesforcountriesemergingfromconflict.1Becauseoftheseconcerns,ICBUWandothershavequestionedthelegalityofDUweapons.However,thisdebateisgenerallyrestrictedtothehumanitarianandenvironmentaleffectsofDU,ratherthanthemilitaryeffectivenessofweaponscontainingDU.Thispaperisintendedtoaddresstheothersideofthedebate,tocriticallyassessandtogivesomecontexttoclaimsaboutthemilitaryutilityofweaponscontainingDU.DUweaponsaredifferentfromothertypesofweaponswhichhavearousedsignificanthumanitarianconcern.Unlikeantipersonnellandminesorclustermunitions,concernisfocusedonaparticularmaterialthatisusedasacomponentofkineticenergyweapons,andnotonkineticenergyweaponsperse.Assuch,DUweaponsdonotrepresentthesoleroutetoachievingadistincttacticaleffect,suchasareadenialordefeatingdispersedtargetsrolesadvocatedforlandminesandclustermunitionsrespectively.Instead,theirperceivedmilitaryadvantagerestsupontheirclaimtobeingmoreeffectiveatperformingaparticularmilitaryrole,comparedtoalternatives.WhileDUweaponsdoconfersomemilitaryadvantageinthatrespect,andthispaperidentifieshistoricalsourceswhichquantifytheextentofthatadvantage,itisclearthatthisadvantagecanalsobegainedthroughothermeans,suchasimprovementstothedesignofammunitionorarmaments.AsDUdoesnotconferauniquemilitaryadvantage,greateremphasisoughttobeplacedonhumanitarianandenvironmentalconcernswhenassessingitsacceptability.WhileICBUWcampaignsagainsttheuseofuraniuminweapons,asanorganisationwedonotadvocatetheuseofanyweapons.WhilediscussionofalternativestousingDUnecessarilyformsasignificantpartofthispaper,itisnotICBUWsroletorecommendalternativematerialsforthemilitaryandthispapershouldnotbereadascallingfortheiradoption.WhileDUhasoccasionallybeenusedinotherroles,2inthemainitsuseisasapenetratormaterialinlargecalibrearmourpiercingroundsfiredbytanksforuseagainstothertanksandarmouredvehicles.ThisistheroleforwhichithasbeensuggestedthatDUisuniquelysuitable.Thispaper

1See:ICBUW.AQuestionofResponsibility:DepletedUraniumWeaponsintheBalkans.Manchester,UK:InternationalCoalitiontoBanUraniumWeapons,2010.

GeneralinformationaboutallaspectsofDUcanalsobefoundonwww.icbuw.org

2TheseincludeaRussianHighExplosiveAntiTankround,the3BK21B,andaRussianairtoairmissile,theR60.ClaimsthatDUisusedinTomahawkcruisemissiles

donotappeartohaveanybasisinfact.


thereforefocusesonthistypeofweapon.DUisalsoemployedinsomeUSmediumcalibrearmourpiercingmunitionsandinstancesoftheiruseagainstnonarmouredtargetsandcivilianinfrastructurehavebeendocumented.GiventhelongstandingconcernsaboutDUweapons,DUsuseintheserolesisevenmorequestionable.

Howeffectiveisdepleteduraniumatpiercingarmour?Historically,tankarmourwascomprisedofplatesofmetalwiththemaindifferentiatingfactorbeingthethicknessofthearmour.Whileeffectivenessagainstthistypeofrolledhomogeneousarmour(RHA)isgenerallyusedasabenchmarkforpenetrators,mostmodernarmourismadeoutofaclassifiedcombinationofmaterialsincludingmetals,ceramics,emptyspaceandexplosiveplates.Theselayersarearrangedtogetherinawaythattestshaveshownoffersgoodprotectionagainstavarietyofthreats,ofwhichkineticenergypenetratorsarebutone.Whilemostammunitionwillhavebeendesignedtobeeffectiveagainstarangeofdifferenttypesofarmourandprotection,theremaybeconsiderablevariationineffectivenessbetweenthesedifferenttypesofarmour.Theeventualcharacteristicsoftheroundarenecessarilytheresultofengineeringcompromisesandassumptionsmadeaboutthetypeofarmouritwillbefiredagainst.ThereasonthatDUisconsideredtobesoeffectiveasapenetratormaterialisthatitcombineshighstrengthanddensitywithatypeofdeformationonimpactknownas'adiabaticsheer'.3Penetratorsaredesignedtodeliverthemaximumenergytotheareastruckoverthelongestpossibletime.Assuch,penetratorsaredesignedtobelongandthin(thedifferencebetweenpenetratorsinthisrespectisusuallyassessedbycomparingtheratioofthelengthanddiameterofthepenetrator).Penetratormaterialsarechosentomaximisestrengthanddensity.Howeverthebehaviourofthematerialundertheextremephysicalconditionsofanimpactalsomakesadifference.Adiabaticsheermeansthatmaterialsloughsofffromthepointofthepenetratorinsuchawaythatitselfsharpens,ratherthanbecomingblunterasitpassesthroughthearmour.Whileotherpenetratormaterials(chieflydifferentalloysoftungsten)areofacomparabledensitytoDU,theyexhibitdifferentdeformationandfracturebehaviours.4Statesaregenerallywaryofreleasinginformationintothepublicdomainabouttheperformanceoftheirweapons.Assuch,itisdifficulttofindinformationinthepublicdomainabouttheeffectivenessofDUmunitionsversusroundsmadewithalternativematerials.Informationwhereonlythepenetratormaterialisalteredandotherroundcharacteristicsremainthesame,soanexactcomparisoncanbemade,isevenmoredifficulttoaccess.DuringinternalUKgovernmentdiscussionsonwhethertobegindevelopingDUammunitionitisstatedthat:workthatbothweandtheAmericanshavecarriedoutsofarshowthatdepleteduraniumpenetratorsgiveanimprovementofabout15%inperformanceoverthebesttungsten

3DUisalsopyrophoric,meaningthatmaterialfromthepenetratorignitesduringimpact.Thisburningmaterialmayignitefuelorammunitionwithinthetargetvehicle,

causingextradamage.However,inthedocumentsexaminedforthisstudy,DUspyrophoricnatureismentionedrarely,ifatall.Itwouldappearthatformilitaryplanners,

penetrationofthetargetvehiclebyakineticenergyroundisconsideredtolikelyhaveadisablingeffectinanycase.Assuchtheextradamagecausedbyphyrophoric

effectsisofsecondaryimportanceifitismentionedatall.

4RobertJ.Dowding,KyuC.Cho,WilliamH.Drysdale,LaszloJ.Kecskes,MichaelA.Minnicino,andMichaelR.Staker.NewMaterialsforTankGunProjectiles:Taking

AimatFutureThreats.MilitaryTechnology33,no.9(September2009):135142.p135


alloypenetrators,presumablydiscussingpenetrationofrolledhomogenousarmour.5AUSgovernmentdocumentfrom1980giveshigherfiguresforadifferent,butrelated,metrictheeffectiverange.6ThesefiguressuggestthatDUofferedanaverageofa52%increaseinpenetrationabovethatofthetungstenalloys;thoughwithinthisaveragetheadvantagerangesfrom12%to157%.Italsoappearedthattheperformancegapincreasedwiththecomplexityofthearmourinthetarget,andthattungstenroundsfailedtopenetratethemostadvancedtarget.7Ofcourse,thesefigureswillnotnecessarilyholdtrueformoderntungstenalloys,orindeedmoderntypesofarmour,whicharedifferentfromthoseusedatthetimeofthesetests.Nevertheless,itseemsreasonabletotreatthesefiguresasindicativeandconcludethatonastrictmaterialtomaterialcomparisonDUisbetteratpenetratingarmourthanpresentlyavailablealternatives.ItisinterestingthattheredoesnotappeartohavebeenanychangetotheDUalloyusedbytheUSsincethe1970s,99.25%DUmixedwith0.75%titanium.8ThisalloyisalsousedbytheUKandFrance,whomanufacturetheirroundsfrommaterialprovidedbytheUS.9Conversely,differentalloysoftungstenhavebeendevelopedovertheyears.Itisperhapssignificantthatinthemid1990sthepenetratormaterialsstrandoftheUK'sprogrammeforincreasingtheperformanceofthe120mmtankgunsystemconcentratedonimprovedtungstenalloys,totheapparentexclusionofresearchonDU.10ThismayhavebeenbecauseresearchonDUwascontinuingelsewhere,butitismorelikelythatDUwasnotthoughttohavepotentialforimprovementasamaterial.TheUSgovernmentdocumentcomparingDUandtungstenpenetratorssaysthattungstenprobablyoffersmoreareasforadvancementorrefinementinmechanicalproperties.11Assuch,itseemslikelythatDU'sadvantagesasamaterialwillbematchedatsomestagebynewcompounds.A2009reviewofalternativematerialsbytheUSArmyResearchLaboratoryidentifiednanocrystallinetungstenandbulkmetallicglasses(BMG)asshowingpromiseinkeyareas,includingexhibitingadiabaticsheer,althoughaprocessforproducingpenetratorsorsimilarlysizedobjectsfromthesematerialswassaidtobestillsomewayoff.12OthervariablesdeterminingtheeffectivenessofkineticenergyroundsItisimportanttonote,however,thatthismaterialtomaterialcomparisonisfarfrombeingthe

5DEFE11/919NewWeaponTechnology,n.d.UKNationalArchives.

6Thiswouldappeartorefertothefurthestdistanceatwhichtheroundwillstillpenetratethetargetinquestion.

7Davitt,RichardP.AComparisonoftheAdvantagesandDisadvantagesofDepletedUraniumandTungstenAlloyasPenetratorMaterials.TankAmmoSectionReport.

USArmyArmyArmamentResearchandDevelopmentCommand,June1980.fhp.osd.mil/du/pdfs/1999279_0000010.pdf.

8Earlieralloys,usedinthePhalanxCloseInWeaponsSystemandtheDaveyCrocketSpottingroundweresupersededbythisalloywhichwasfirstdevelopedfor

ammunitionfortheUSA10gunship.SeePeterKJohnson.TungstenVersusDepletedUraniumforArmourPiercingPenetrators.InternationalJournalofRefractory

Metals&HardMaterials(December1983):179182andDavitt,op.cit.

9Trueman,E,S.Black,andD.Read.CharacterisationofDepletedUranium(DU)fromanUnfiredCHARM3Penetrator.ScienceofTheTotalEnvironment327,no.1

3(July2004):337340,p337ValrieChazel,PascaleHoupert,andFranoisPaquet.DepletedUraniumUsedinWeaponsandtheFrenchNuclearIndustry.InDepleted

Uranium:Properties,Uses,andHealthConsequences,editedbyAlexandraCMiller,2153.BocaRaton,FL:CRCPress,2007,p25.

10SeeRJMills.AnnualAssignmentReportArmouredFightingVehicles(LightAndHeavy)RO5A120mmStretchProgram,April26,1995.TankMuseum

Archive,Bovington.p65,whereitisstatedthatthepenetratormaterialcomponentoftheprogrammehasaparticularfocusontungstenalloys,butnomentionismadeof

DU.

11Davitt,op.cit.,p8

12Dowdinget.al,op.cit,.p135138


soledeterminantofthemilitaryutilityofDUweapons.Penetratormaterialisonlyoneamongmanyvariableswhichdeterminetheeffectivenessofakineticenergyround.AlthoughDUappearstobethemosteffectivematerial,itisquitepossibletoachievesimilarimprovementsinperformancebyothermeans.Othersignificantvariablesthatcanbeadjustedtoincreasetheeffectivenessofarmourpiercingroundsincludethedimensionsandshapeoftheroundparticularlyincreasingtheratioofthelengthtothediameter.Reducingtheweightorotherperformanceimprovingchangestothesabot(thepartoftheroundwhichallowsthethinsubcalibrepenetratortositwithinthelargerbarrel)canincreasevelocity,ascanmodificationstothebarrelorimprovementstotheexplosivecharge.13Forexample,thepenetrationabilityoftheUSM829roundhasbeenimprovedbyincreasingitslength,andalsobyusinglightermaterialsforthesabot.Similarly,ammunitionfortheGermanLeopard2tankhasbeenimprovedbymodificationstothepenetrator,sabotandpropellant,whichhaveincreasedthepenetratorweightbuthavealsomeantthattheroundleavesthebarrelwithincreasedkineticenergy.14LaterversionsoftheLeopard2arealsofittedwithalongergunbarrel.Thismeansthattheexplosiveforceofthechargehaslongertoactonthepenetratorasittravelsupthebarrel,increasingthevelocityoftheround.15Thissuggeststhatmodificationstotheround,gunorotherfactors,whichareunconnectedtothechoiceofpenetratormaterial,willoftengivemoresignificantimprovementstoperformancethanchangingpenetratormaterial.ThisisclearlyshowningovernmentdocumentsfromDUuserstateswhich,whendiscussingotherchangestoammunition,statethatthesechangeswillgivegreaterimprovementsinperformancethanthedifferencebetweenDUandalternativematerials.Forexample,UKgovernmentpapersdatingfrom1978whenthedecisionwasmadetodevelopafinstabilised120mmAPFSDSround,insteadofthethentraditionalAPDSround,16statethataDUAPDSroundwouldnotbeequaltotheprojectedadvancesinSovietarmour,andthereforeatungstenAPFSDSroundshouldbedevelopedinstead.17Similarly,whendiscussingthepossibilitythatpoliticalobjectionstoDUweaponscouldpreventthembeingdeployedtoNATOforcesinEurope,a1980USdocumentpredictsthatthecapabilitiesoftheDUXM774roundcouldbeexceededbyatungstenversionoftheXM833round,itssuccessor.18WiderdeterminantsoftankwarfareeffectivenessTheantiarmourcapabilityoftanks19isdependentonnumerousvariablesbesidesthebasic

13R.M.Orgorkiewicz.TransformingtheTank.JanesInternationalDefenceReview(October1997):3039.

14Ness,LelandS,andAnthonyGWilliams.JanesAmmunitionHandbook20102011.Coulsdon:IHSJanes,2010.pp404405418421.

15RupertPengelley.120mmSmoothboreDevelopersVieforLeadershipinLightWeightandLethality.JanesInternationalDefenceReview(May1,2004).

16Priortotheadventof120mmguns,mosttankgunswererifledtogivetheroundsspinastheyflew.Thespinoftheroundgivesitstabilityinflighttherebyincreasing

theaccuracyoftheshot.RifledgunsfiredArmourPiercingDiscardingSabot(APDS)rounds.ArmourPiercingFinStabilisedDiscardingSabot(APFSDS)roundsare

equippedwithfinswhichgivethemspininsteadandcanbefiredfromsmoothboreguns,whichallowsforagreatermaximummuzzlevelocity.

17R.A.R.D.ETechnicalProjectDocument22/78(Tk.Wpns)M.V.E.E.FVT35/563AnImprovedKineticEnergyRoundforChieftain.MinistryofDefence,April

1978.22/78p8

18Davitt,op.cit.,p20.

19Althoughthishashistoricallybeenthetypeofencounterthattankshaveprimarilybeendesignedfor,itisamatterofsomedebatewhetheritisasrelevantto

contemporarytankwarfare.However,asDUroundsareantiarmourroundsdesignedwiththistypeofencounterinmind,itistheappropriatecontextforjudgingtheir

effectiveness.


engineeringcharacteristicsoftheammunitionandgun.20Theaccuracyofashot,thespeedatwhichitcanbefiredinresponsetosightinganenemyandtherateoffirecanallplayacriticalroleintankontankconfrontations.21Significantfactorsthen,gobeyondeventechnologicalimprovementssuchastargetingsystemsandengines.Theyalsoincludefactorssuchascrewtraining,doctrineandergonomics,22allofwhichmustbeincorporatedintodecisionmakingatthedesignandprocurementstage.Assuch,itisamistaketofixateononeparticularvariable,inthiscasepenetratormaterial,andoveremphasiseitsimportancetotheexclusionofallothers.Whilemanyofthesemetricsmaybeimprovedwithoutcompromisingontheothers;anditmightbesupposedthatdesignerswillstrivetomaximiseperformanceoneachconceivablecriterion,inrealityattentionandresearchfundingcanonlybediverteddownalimitednumberofavenues.Few,ifany,ofthecriteriawhichcontributetotheantiarmourcapabilityoftanksaresosignificantthatanycomparativedisadvantagesinthatfieldcannotbeoffsetbygainsinanother.Certainlythisisnotthecasewhenselectingpenetratormaterial.

Thebestmaterialforthejob?AhistoricalcasestudyofthedevelopmentoftheBritishCHARMroundsandChallenger1tankWhileasimpleconceptionofammunitiondevelopmentmightstatethatthemosteffectivematerialshouldalwaysbechosen,inreality,procurementanddevelopmentdecisionsaremorecomplicated.ThisisbestillustratedusingacasestudyoftheBritishChallenger1tankandtheDUroundsdevelopedforit,andthecontextwhichinformedthesedevelopmentchoices.Ratherthanaimingforanabstractmaximumeffectiveness,antiarmourtankammunitionisdesignedtodefeatspecificarmourconfigurations.Itisjudgedagainstitsabilitytodefeatarangeofarmourfieldedbypotentialenemiesandonpredictionsoffutureenemyarmourdevelopments.AtthetimewhentheChallengeranditsammunitionwerebeingdeveloped,thisspecificallymeantSoviettankarmour.Inthe1970s,atrilateralagreementexistedbetweentheUK,USandWestGermanytoequiptheirtankswithacommongun,sothattheirseparatetankshadinterchangeableammunition.23Duringtrilateraltrialsin1975,theUKfieldeda110mmrifledgunwithAPDSammunition.24ThiswasoutperformedbytwoAPFSDSroundsaGermanroundfiredfroma120mmsmoothboregunandthenewUSDUXM774round,firedfromanolderBritishgunbarrel,theL7.25Uptothistime,theUKhadbeenaleadingnationintankdevelopmentandhadbeentheoriginofanumberof

20These are much more numerous than the few key factors already discussed, and include barrelwear, gun alignment, barrel bend, barrelweight, barrel stiffness,

expansion of the barrel, temperature and barrel wear (See AFV TechnologyAide Memoire.Armour School RAC Centre, March 1979. Tank MuseumArchive,

BovingtonHDWarwick.AThirdSupplementtoMVEEReport82019AGuideToTheDesignofMainArmamentGunMountingsForArmouredFightingVehicles

(U).ProcurementExecutiveMinistryofDefence,1987.TankMuseumArchive,Bovington.)

21ReasonsfortheDevelopmentofa120mmHighPerformance,SmoothBoreGunwithFinstabilizedAmmunition,n.d.TankMuseumArchive,Bovington.p5

22ThirdsupplementtotheMVEEreport,op.cit.pD

23R.M.Orgorkiewicz.ArmouredFightingVehicles.InColdWar,HotScience:AppliedResearchinBritainsDefenceLaboratories,19451990,editedbyRobertBud

andPhilipGummett.London[England]:NMSITradingLtd.:ScienceMuseum,2002.p124125

24ThedifferencesbetweenAPDSandAPFSDSareoutlinedinfootnote5,above.

25RupertPengelley.BritishTankGunDevelopment.DefenceAttach,no.1(1981),p18


successfulinnovations,includingAPDSrounds,thenthestandardtypeofarmourpiercingammunition.Atthetime,therewerestillquestionsovertheaccuracyofAPFSDSroundsbutthedecisiontofieldanAPDSroundwasprobablyalsodueinparttoaninstitutionalunwillingnesstoacceptthatthisBritishinventionhadbeensupplanted.26AlthoughtheUKsubsequentlydevelopedaprototype120mmAPFSDSroundforsubsequenttrials,boththeUSandWestGermanyadoptedacommonsystem,the120mmsmoothboreL44gun.27MeanwhiletheUKplannedtodevelopanewtankonitsownwithadifferent120mmrifledgun.28Thiswaspartlyjustifiedasbeingnecessarytoretaincompatibilitywithexistingammunition,includinganotherBritishinvention,theHESHround.29However,subsequentdecisionswereprimarilytheresultofexternalcircumstances.Firstly,projectionsforfutureimprovementsinSovietarmourwererevisedupwards,leadingtothedevelopmentofatungstenAPFSDSround(asmentionedaboveaDUAPDSroundwasnotdeemedsufficient).30ThenanilladvisedplannedsaleoftankstotheShahofIrandidnotgoaheadduetohisoverthrowintheIslamicRevolution.ThelossofthissalethreatenedthefutureoftheRoyalOrdnancefactoryinLeedswhichhadbeenduetoproducethem.31Thirdly,projectionsofthetypeofarmourexpectedinthesuccessortotheSovietT80tankindicatedthattheplannedtungstenAPFSDSroundwouldnotbeabletofullypenetrateit.32Asthecostsoftheprogrammeforthenewtankwerealsoincreasing,itwasdecidedthattheUKwouldtakeuptheshortfallfromthefailedIraniansale.33ThetankinquestionwasactuallyaderivativeoftheChieftaintankalreadyfieldedbytheUK,butwastobeknownasChallenger1.AstheChallengerwasequippedwiththesame120mmrifledgunastheChieftain,anewhighpressure34gunwouldbedesigned,whichcouldberetrofittedtoboththeChallengerandChieftain.ADUroundwouldbedevelopedforthisgun(knownastheL30),butitwouldbebackwardscompatiblewiththeChieftainammunitiontheninservice.35ItisquiteclearfrominternaldocumentsfromthistimethatdevelopmentwasspecificallyfocuseduponovercomingSovietarmourcapabilities.36TherewereformalagreementsbetweentheNATOcountriestodeviseaccuratesimulationsofarmourarraysfordifferenttypesofSovietvehiclestousefortesting.37ThedetailinUKammunitionprocurementdocumentsshowsthatthesecriteria

26OrgorkiewiczArmouredFightingVehicles,op.cit.,p125

27Pengelley.120mmSmoothboreDevelopersVieforLeadership,op.cit.

28ThiswasknownastheMBT80,presumablyareferenceto1980,thensometimeinthefuture.Priortothat,theUKhadbeenplanningtojointlydevelopatankwith

WestGermany,butthatprojectappearstohavesouredduringthetimeofthetrilateraltrials,presumablyasaresultofthefailuretoagreeonacommonbarrelforthethree

nations.ThetanktheGermansthendevelopedalonebecamethehighlysuccessfulLeopard2

29HighExplosiveSquashHead(HESH).ThistypeofroundwasnotwidelyadoptedbynationsotherthantheUK,andwasnotdesignedwithfins,andsorequiredthe

rifledbarreltogiveitspin.However,asOrgorkiewicz(ArmouredFightingVehicles,op.cit.,p125)pointsout,itwouldnothavebeendifficulttoaddfinstotheround

30DSABoyd.GSR(OE)3758DraftReportforPreliminaryAcceptance.ProcurementExecutiveMinistryofDefence,February8,1983.TankMuseumArchive,

BovingtonR.A.R.D.ETechnicalProjectDocument22/78,op.cit.,p8


32SeeGSR3851120mmUniversalDepletedUraniumAPFSDSRound.MinistryofDefence,October1,1980.TankMuseumArchive,Bovington.Incidentally,the

additionofalongerbarreltotheGermanLeopard2tankwasintendedtocounterthearmourinanupgradetotheT80:theT80U,seePengelley.120mmSmoothbore

DevelopersVieforLeadership,op.cit.


34i.e.abletowithstandfiringswithamorepowerfulexplosivechargeandthereforetofiremorepowerfulammunition

35GSR3851,op.cit.

36GSR(OE)3758,op.cit.GSR3851,op.cit.

37Package03BHeavyandLightArmouredVehiclesQuarterlyReviewDocumentReportforthePeriodAprJun94.DefenceResearchAgency.TankMuseum

Archive,Bovington


werebasedonprojecteddevelopmentsinSovietarmour.DuringcivilservicediscussionspriortothedevelopmentprogramforaUKDUround,itisspecificallystatedinreferencetotheneedforammunitiontocounterSovietarmourthat:DUappearstoofferthebestprospectsofsuchanimprovementfortheChieftainsmainarmamentinashorttimescale.38Inotherwords,UKDUammunitionwasdevelopedbecauseitwasdeemednecessaryfordefeatingaparticulartypeofarmourandcircumstanceshadlimitedthepossibilitiesforadjustingothercharacteristicsoftheweaponssystemwithoutaconsiderableinvestmentoftimeandmoney.39ConsequencesforpresentdayUKtankammunitionThedeploymentofthenewgunwasdelayedduetoproblemswiththeChallenger1tank,whichnecessitatedamorefundamentalupgradetothewholeUKtankfleet.Theupdatedtank,whichfeaturedthenewgun,wasknownastheChallenger2andenteredservicein1993.DUammunitioncompatiblewiththeearliergunwasproducedfortheChallenger1justbeforethestartoftheGulfWarin1991.AhighpressureDUround,knownasCHARM3,finallybecameavailablein1999,andremainstheUKsmainantiarmourtankammunition.Ratherthanthebrandnewtankenvisagedbymilitaryplannersintheearly70s,in2012theUKisfieldingatankwithagunthatistheresultofevolutionaryadaptationsfromtheChieftain,wherebackwardscompatibility40hasbeenaconsiderationateachstage.41Asaresult,designoftheCHARM3roundisdeterminedinpartbydecisionstakenforatankwhichfirstcameintoservicein1965.Theseincludearifledgunbarrel,whichmakesUKammunitionincompatiblewithotherNATOcountries,andammunitionthatiscomprisedofaseparatechargeandprojectile.ThismeansthatthereisnophysicalspaceintheroundtoaccommodatealongerpenetratorthanthatfoundinCHARM3,meaningthatthesimplestammunitionredesignoptionisnotapossibility.42AsneitherChallengermodelhasbeensuccessfulontheexportmarket,43therehasbeenlittledemandfortheammunition,resultingintheclosureofthefacilitiesusedtomanufactureCHARM3.Whencombinedwiththediminishingimportanceoftankwarfareinmilitarypriorities,thesedevelopmentshavepreventedanyfurtherdevelopmentofUKarmourpiercingammunition.Meanwhile,theGermanL44smoothboregun,adoptedbyboththeUSandGermanyafterthe1975trilateraltrialshasbecomethedefactoNATOstandard,andisusedworldwide.44

38DEFE19/267DepletedUranium:UseinConventionalArmamentResearchFirings,n.d.UKNationalArchives.Itshouldbenotedthatotherconsiderationsdoplaya

roleinthesediscussions,suchastheimplicationsforarmssalesifothernationsoffertosellDUammunitionandtheUKdoesnot,andthecostofthematerials.However

theseclearlyplayasecondaryroletotherequirementforammunitionthatcanpenetrateacertainamountofarmour(SeealsoDEFE11/919NewWeaponTechnology,op.

cit.andDEFE19/266DepletedUranium:UseinConventionalMunitionsResearchFirings,n.d.UKNationalArchives)

39Inasimilarvein,thefirstUSDUround,theXM774,grewoutofa1973projecttoimprovethelethalityoftheexistingM68gun,soextendingitslife(SeeOfficeofthe

SpecialAssistanttotheSecretaryofDefenseforGulfWarIllnesses.1991DUUseGulflinkTABEDevelopmentofDUMunitions,

n.d.http://www.gulflink.osd.mil/du_ii/du_ii_tabe.htm.)

40i.e.compatiblewithearlierversions.Inthiscasegunshavebeendesignedtobecompatiblewitholderammunitionandammunitionhasbeendesignedtobecompatible

witholderguns


42Thiswouldlikelynothavebeenconsideredaproblemin1965,notleastbecauseAPDSroundshaveanupperlimittotheirlength/diameterratio.SeeDOSWhitley.

120mmTankGuns.DefenceSales.TankMuseumArchive,Bovington.pA1

43OnlyOmanhasbroughtnewChallenger2tanks.TheUKsChallenger1fleetwastransferredtoJordanwhentheUKupgradedtoChallenger2

44Pengelley.120mmSmoothboreDevelopersVieforLeadership,op.cit.


LessonsfromtheCHARMcasestudyAlthoughthisexamplemaywellincludeparticularlyunfortunateprocurementdecisionsanddelays,therearecharacteristicswhichwillbecommontoallammunitiondesignandprocurementprocesses.Ratherthanstartingwithablankslateandchoosingthebestmaterialforthejob,decisionsaretakenwithinawiderpoliticalandeconomiccontext,whichmaybeconsiderablymoreimportantindeterminingroundcharacteristicsthanpureengineeringconsiderations.Thelegacyofpreviousdecisionsandissuesaroundcompatibility45standoutasbeingamongstthemostsignificantfactors,thoughitshouldbenotedthatdecisionmakingonallthesemattersiscolouredbygroupthinkandinstitutionalpreferences.ThisisbynomeansrestrictedtoBritishprocurement.AnotherexamplewouldbetherejectionofChobhamcompositearmourbytheUSMilitaryonthebasisofearlytests.46Pursuingincrementaldevelopmentsofexistingsystems,ratherthandesigningsomethingentirelynew,clearlyconveysbenefitsintermsofcost,timerequired,andreliability.Presumablythepreferredpositionforplannersintermsofammunitiondevelopmentistohaveaselectionofrelativelylowcostchangeswhichcanbefairlyquicklyimplementedinexistingammunitionaccordingtorequirements.Thesechangescanbeimplementedagainstabackdropoflongerterm,moreinvestigativeresearchintomorefundamentalchanges.Theaimofthisstanceistoensurethatwhenincrementalchangesarenolongersufficientorpractical,thecostsandbenefitsofdifferentdevelopmentoptionsarewellunderstood,andthetimescaleandcostofdevelopingprototypesintoservicecanbeestimatedwithsufficientaccuracy.TowardstheendoftheColdWar,severalsignificantstepchangesintankgunsystemswereenvisaged,withanunderstandingthatacommon140mmNATOgunwouldbedeveloped.Thiswasthenlikelytobereplacedwithagunusingelectromagneticpropulsion.47Intheevent,neitherofthesedevelopmentshasbeendeemednecessary,duetotheendoftheColdWarandtheconsiderableslowingofRussiantankdevelopment.48Instead,NATOtankammunitiondevelopmenthasrestricteditselftoimproving120mmammunition.Sincearound2002,UKplannershaverecognisedthatforreasonsofcostandcompatibility,futureBritishtankammunitionwouldhavetobesmoothboreammunitionofthetypeusedbyotherNATOcountries.49Tothisend,theChallenger2tankhasundergonetestingwithaGermanmadesmoothboregunandnonDUammunition,whichhasapparentlyproventobemoreeffectivethanCHARM3ammunition.50However,duetoreasonsofcost,thisupgradehasnotbeenimplemented.

45ThoughitshouldbenotedthatthisexampleisunusualinhavingtwoconflictingcompatibilityimperativescompatibilitywithNATOallies,andbackwards

compatibilitywiththeChieftaintank

46ItseemsthattheUSsawanearlyprototypeofthiskindofarmour,anddismisseditspotential,possiblybecauseearlyversionswerelesseffectiveagainstkineticenergy

rounds.ItwassubsequentlyadoptedasthearmourfortheAbrams,butonlyduetothevociferouscampaigningonthepartofafewindividualsagainstthesettled

institutionalopinion.Forafulldescriptionofthisturnofevents,seeKelly,Orr.KingoftheKillingZone.NewYork:W.W.Norton,1989

47M.J.Wright,ProjectsDirector.MemorandumFutureGunSystems.RoyalOrdnance,August16,1988.TankMuseumArchive,Bovington.p12

48Thisisaptlyillustratedbythe2010cancellationoftheRussianT95tank,whichwastohavebeenarevolutionarynewdesign(seeJamesMWarford.TheSovietFST2

andtheRussianT95:TheNewRussianTankGenerationComingintoFocus.AfricanArmedForcesJournal(September2010):1821),butwhichbecameobsoleteduring

twodecadesofdevelopment(seeRussianTankFallsVictimtoIntriguesRusBizNews.com,n.d.http://www.rusbiznews.com/news/n795.html).Asaresult,itcouldbe

arguedthatfrontlineRussiantankshavenotundergoneanymajorchangessincethegenerationofvehiclesthattheUKsoriginalCHARMammunitionwasdesignedfor

49Thefactthatthisinevitabledevelopmentwasonlyinternallyadmittedatsuchalatestage,followingthedecisionbyGreecenottoadopttheChallenger2tank,

illustratestheroleinstitutionalintransigenceplayedinthiscase(seeRupertPengelley.TransitionofChallenger2toSmoothboreArmamentReachesSignificant

Landmark.InternationalDefenceReview(March1,2006))

50ThiswasfirstreportedbythewellconnecteddefencejournalJanesInternationalDefenceReview,followingtrailsinFebruary2006,Ibid.Althoughtheresultsofthe

trialswereofficiallyclassified,JaneswasinformedofftherecordthatthetestconfigurationoutperformedaCHARM3roundfiredfromtheexistinggun.


ItissomewhatironicthatBritishgovernmentministersoftendefendtheircurrentDUammunitionasbeingthebestmaterialforthejob,havingfailedtobringinamoreeffectivenonDUalternative.Theclearimplicationisthat,whileonastrictmaterialtomaterialcomparisonDUmaybemoreeffectiveatpiercingarmourthancurrentalternatives,thiseffectivenessdoesnotequatetoanabsolutemilitaryadvantage.Thesameeffectivenesscanbeachievedthroughothermeans.TheUKsswitchtoDUammunitionallowedthemaoneoffincreaseinpenetration,meaningthatotherprocurementdecisionscouldbetakenforreasonsofbackwardscompatibilityandtosupporttheBritishdefenceindustry,ratherthanmaximisingeffectiveness.However,inthelongrun,thishasnotpreventedtheroundfrombecominglesseffectivethanthenonDUsystemusedbyGermany.

ConclusionAsthecasestudyshows,thefactorsaffectingammunitiondesign,andpenetratormaterialchoice,arefarremovedfromasimplecaseofchoosingtheammunitionwiththegreatestpossiblemilitaryutility.Althoughstraightforwardengineeringprincipleswillinformthedecision,widerconsiderationsmaybemuchmoresignificant.ItistechnicallypossibletodesignweaponsystemsthatareequallyaseffectiveasDUusingalternativematerials.ThisisparticularlytrueinthepostColdWarerawhenthearmsracebetweendifferentarmoursandpenetratorshaslargelyceased,oratleastconsiderablysloweddown.AllthatisrequiredisthepoliticalwillforchangewithinuserstatestodiscontinueusingDUand,iftheywishtodeveloptheirownbespokerangeofammunitionsystems,tospendthenecessarysumsondevelopment.AlthoughDUmay,onconsiderationofpenetratormaterialalone,bebetteratpenetratingarmour,thisadvantageisnotsogreatthatotheradaptationscannotbesubstituted.Furthermore,whenconsideredinlightofthenumerousdisadvantagesofusingDUthepotentialhealthandpsychologicalimpactonciviliansandmilitarypersonnel,theenvironmentalcontamination,handlingissues,thecostofdecontamination(i.e.cleaningupdomesticrangesandproductionfacilities),potentialliabilitiesfordecontaminationoverseasandthepoliticalunacceptabilityinmanyquarters,ICBUWbelievesthecostswelloutweightheperceivedbenefits.TherearesomeindicationsthatthispointofviewisspreadingfromthemanycountriesthathaveneversoughttouseDUweapons,tosomeofthestateswhichwerepreviouslythemostenthusiastic.TheUnitedStateshastakenalongtermdecisiontodiscontinueusingDUinmediumcalibrerounds.Strikingly,whentenderingthecontractfortheammunitionfortheF35JointStrikeFighter,theUSlistedthepresenceoftoxicmaterialssuchasCobalt,Nickel,BerylliumordepletedUraniumasbeingnondesirablecriteriaforpotentialbidders.51TheylaterpurchasedatungstenbasedroundfromtheGermanmanufacturerRheinmetall,astheyweretheonlysuppliertosatisfyalltherequirements.AlthoughtheycurrentlyretaintheA10gunshipinservice,whichfiresa30mmDUround,during2011sOperationUnifiedProtectorinLibyaitappearsthatadecisionwastakennottousetheDUammunition,presumablybecauseofitspoliticalunacceptability.52

51U.S.AirForceAirArmamentCenter.DualPurposeAmmunitionfortheF35AircraftGunSystem(GAU22A)FinalRequirementsList,April24,2008.Federal

BusinessOpportunitiesSolicitationNumberAAC685ARSS080424.https://www.fbo.gov/utils/view?id=f934399b74944eb51de1ec687f89bba8

52USdeniesdepleteduraniumuseinLibya,butrefusestoruleoutfutureuse:http://www.bandepleteduranium.org/en/a/402.html


RecentreportssuggestingthattheUSisalsoplanningtodevelopanonDUsuccessortoitscurrent120mmDUroundappeartoconfirmthispicture.53WhileDUmayatpresentbethemosteffectivepenetratormaterialinastrictmaterialtomaterialcomparison,thisdoesnotmeanthatDUammunitionissomilitarilyusefulthatalternativescannotbefound,givensufficientresourcesandpoliticalwill.GiventhenumerousproblemsregardingDUasamaterial,thecaseforuserstatestoabandontheseweaponsisunanswerable.

53NATOTanksAimatWiderTargetSetwithSmoothboreAmmunition.InternationalDefenceReview(January19,2012)

Documents

An Analysis of the Utility of Depleted Uranium in Kinetic Energy Penetrators 187