The Radar Game - Air Force Association · 2010. 9. 30. · On September 12, 1918 at St. Mihiel in France, Col. Wil-liam Mitchell became the first person ever to command a major force

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A MITCHELL INSTITUTE STUDY

The Radar GameUnderstanding Stealth and Aircraft Survivability

By Rebecca Grant September 2010

A mitchell inStitute Study

On September 12, 1918 at St. Mihiel in France, Col. Wil-liam Mitchell became the first person ever to command a major force of allied aircraft in a combined-arms opera-tion. This battle was the debut of the US Army fighting under a single American commander on European soil. Under Mitchell’s control, more than 1,100 allied aircraft worked in unison with ground forces in a broad offen-sive—one encompassing not only the advance of ground troops but also direct air attacks on enemy strategic tar-gets, aircraft, communications, logistics, and forces beyond the front lines.

Mitchell was promoted to Brigadier General by order of Gen. John J. Pershing, commander of the American Expeditionary Force, in recognition of his com-mand accomplishments during the St. Mihiel offensive and the subsequent Meuse-Argonne offensive.

After World War I, General Mitchell served in Washington and then became Commander, First Provisional Air Brigade, in 1921. That summer, he led joint Army and Navy demonstration attacks as bombs delivered from aircraft sank several captured German vessels, including the SS Ostfriesland.

His determination to speak the truth about airpower and its importance to America led to a court-martial trial in 1925. Mitchell was convicted, and re-signed from the service in February 1926.

Mitchell, through personal example and through his writing, inspired and en-couraged a cadre of younger airmen. These included future General of the Air Force Henry H. Arnold, who led the two million-man Army Air Forces in World War II; Gen. Ira Eaker, who commanded the first bomber forces in Europe in 1942; and Gen. Carl Spaatz, who became the first Chief of Staff of the United States Air Force upon its charter of independence in 1947.

Mitchell died in 1936. One of the pallbearers at his funeral in Wisconsin was George Catlett Marshall, who was the chief ground-force planner for the St. Mihiel offensive.

ABOUT THE MITCHELL INSTITUTE FOR AIRPOWER STUDIES: The Mitchell Institute for Airpower Studies, founded by the Air Force Association, seeks to honor the leadership of Brig. Gen. William Mitchell through timely and high-quality re-search and writing on airpower and its role in the security of this nation.

Brig. Gen. Billy Mitchell

Published by Mitchell Institute Press© 2010 Air Force AssociationDesign by Darcy Harris

ABOUT THE AUTHOR: Dr. Rebecca Grant is an airpower analyst with 20 years of experience in Washington, D.C. She is President of IRIS Independent Research and serves as director, Mitchell Institute, for the Air Force Association. She has written extensively on airpower and among her most recent publications are several Mitchell reports, including The Vanishing Arsenal of Airpower (2009), The Tanker Imperative (2009), and Airpower in Afghanistan (2009).


By Rebecca Grant

September 2010A mitchell inStitute Study


FOREWORD 6

INTRODUCTION 8

SURVIVABILITYBEFORERADAR 10

THERADARGAMEBEGINS 15

THEPOSTWARRADARGAME 23

WINNINGTHERADARGAME 29

SIGNATUREREDUCTIONANDMISSIONPLANNING 36

LOWOBSERVABLESINTHEOPERATIONALENVIRONMENT 44

CONCLUSION:THEFUTUREOFSTEALTH 53

ENDNOTES 56

THE RADAR GAME: Understanding Stealth and Aircraft Survivability

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Radio aids to detection and ranging ... radar—as it’scommonly called—transformed air warfare in 1940. Ithasheldagriponwould-beattackersanddefenderseversince.

ThisspecialreportfromtheMitchellInstituteforAirpowerStudies isarepublicationofa longessay Iwrote in1998togetatwhystealthwassuchanimportantbreakthroughforairpower.Then,asnow,therewerequestionsaboutthefutureofstealth.

Consider the times. The dazzling combat success of theF-117intheGulfWarof1991hadbeenfollowedbythecan-cellationof theB-2 stealthbomberprogram in1992.Cuts totheF-22stealthfighterprogramhadalreadybeenmade.Ex-periencedairmenwere strongly in favorof stealth. Someof-ficials,likeformerSecretaryofDefenseWilliamPerryandthen-UndersecretaryofDefenseforAcquisitionPaulKaminski,werethoroughlysteepedintheworkingsofstealthanditsbenefits.But for many, intricate stealth programs seemed a question-able investmentgiven thedecliningdefensebudgetsof thelate1990s.Stealthwaswrappedupinthevalueofairpowerasawholeandinthere-evaluationofAmericansecuritypolicies.

Still,adozenyearsagotherewasastrongcommitmenttostealth.TheAirForce,Navy,andMarineCorpsalongwithBritainhadcommittedtotheJointStrikeFighter.TeamsledbyLockheedMartinandBoeingwereworkingondesigns.Per-hapsmostimportant,thelong-rangeAirForcebudgethadaplantofieldanall-stealthfighterforceofmorethan2,200fighters.Thefutureofstealthseemedassured.

Combat experience quickly revalidated its importanceduringthe1999NATOairwarwithSerbia.B-2sflewmissionsintoheavilydefendedairspaceanddideverythingfromtak-ingouttheNoviSadbridgetoattackinganddestroyinganSA-3surface-to-airmissilebattery.F-117sflewcrucialmissions.(OneF-117wasshotdown.)TheintensiveairwarwithIraqinearly2003againsawtheuseofbothF-117sandB-2sagainstavarietyoftargetsinandaroundBaghdad.

Sincethen,stealthhascomeunderassault.The reasonshave much to do with strategy, politics, and budgets, andlittletodowiththecapabilityassessmentsthatdrovethede-cisionstodevelopandbuystealthaircraftinthefirstplace.

Theradargameitself is justascriticalas itwasadozenyearsago.Radarremainstheleaderintechnologiesforde-tectingaircraftandmissileattack.Asthestudynotes:“Whywereaircraftsovulnerabletoradardetection?Inshort,forallthereasonsthatincreasedtheiraerodynamicqualitiesandperformance.Metalskins,largeverticalcontrolsurfaces,bigpowerfulengines”andsoon.

Thestudydetailshowthefirstroundsoftheradargamewere all about electronic countermeasures. RAF BomberCommandfamouslyheldbackthefirstuseofchaffforoverayear,fearingthattheGermanswouldimplementcounter-measures,too.DuringtheColdWar,electroniccountermea-suresandelectroniccounter-countermeasuresbecameoneof theblackestartsofairpowerandoneof itsmost impor-tant.Stealthwasinpartawaytobreakthetug-of-war.

That was why stealth was so attractive. Attackers mustundotheadversary’sadvantageeitherbylow-levelingress,high-altitude operations, speed, electronic countermea-sures,orstealth.Ofthese,theabilitytodiminishtheeffectsofradarreturnisoneofthemostchallengingandoneofthemostrewarding.Alowobservableaircraftgainsadvantagesin how close it can come to air defense systems. Low ob-servableaircraftdonotgetafreepassinthebattlespace.Lowobservabilityhastobefine-tunedtodefeatadversarysystemsastheyestablishandhand-offtracksandzeroinonfirecontrolsolutions.Notmuchwillpreventthebigbumpoflong-range, low frequency radarsused for initialdetection.But,ittakesmuchmorethanablipona“TallKing”radartounravelawell-plannedmission.

Over thepastdecades, it’sneverbeeneasytoconveywhatlowobservabletechnologiesactuallydo.Understand-ingthemrequiressomegraspofphysics,ofradarphenom-

Foreword

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enology,ofaircraftdesign,ofhowmissionsareplannedandexecuted. One hears so often that stealth is not invisibility.The inversecorollary is thata single radardetectionofanaircraftatapointintimeandspacedoesnotequalanim-penetrablebattlespace.TheBritishnickname“ChainHome”fortheircross-Channelradarsuitehaditaboutright.Ittakesa chain of detections, interpretations, and correct actionsbydefenderstointerceptanaircraft.Stealthbreaksupthechain by removing, reducing, or obfuscating a significantpercentageofthosedetectionopportunities.

MuchofThe Radar Game isdevotedtoabasicdiscus-sionofhowstealthworksandwhyitiseffectiveinreducingthe number of shots taken by defensive systems. Treat thislittleprimerasa steppingoffpoint fordiscoveringmoreofthecomplexitiesoflowobservability.

Ofcourse,thereisawiderelectromagneticspectrumtoconsider.Whileradar isthefocushere,truesurvivabilityde-pends on taking measures to reduce visual, acoustic, andinfraredsignaturesaswellasminimizingtelltalecommunica-tionsandtargetingemissions.

Thedarlingofpassivetechnologiesisinfraredsearchandtrack.Thoseincombatignoretheinfraredspectrumattheirperil.Although it is not as often in the headlines, designersofall-aspectstealthaircrafthaveworkedsincethe1970stominimizeinfraredhotspotsonaircraft.

Finally,electroniccountermeasuresstillhavetheirroletoplay.Asbefore,itwilltakeacombinationofsurvivabilitymea-surestoassuremissionaccomplishment.

The Radar Gameshouldalsoshedlightonwhycomplextechnologies like stealth cost money to field. The quest forstealth is ongoing and the price of excellence is nothingnew.Take,forexample,theP-61BlackWidow,whichwasthepremier US night fighter of lateWorldWar II. This all-black,two-engine fighter was crewed by a pilot in front and adedicated radar operator in the back seat. Its power andperformance were terrific advances.“All this performance

OriginalCopyright1998RebeccaGrant

Acknowledgements from 1998 version: The author would liketo thankDr. ScottBowden forhisassistancewithhistorical re-search.Also,theauthorwouldliketoextendspecialthankstoTomMcMahon,PhilSoucy,KenMcKenzie,andCharlesMasseyofModernTechnologySolutionsInternational,ofAlexandria,VA,forconductingthesimulationsofsignatureshapesinanairde-fenseenvironmenttoillustratethetacticalbenefitsofstealth.

camewithahighpricetag,”notedStevenL.McFarlandinhis1997AirForcehistoryConquering the Night.“WithNorthrop’sassemblylineinfullgear,acompletelyequippedP-61cost$180,000in1943dollars,threetimesthecostofaP-38fighterandtwicethepriceofaC-47transport.”

Winning the radar game still carries a substantial pricetag—but stealth aircraft pay back the investment in theircombatvalue.

Stealthremainsattheforefrontofdesign.Oneofthebestsignals about the ongoing value of stealth lies in new ap-plications.Leadingunmannedaerialvehiclesforhigh-threatoperations incorporate stealth. Navy ships have adoptedsome of its shaping techniques. Of course, the F-35 JointStrikeFighter remains thenation’s singlebiggestbeton fu-tureairpower.

Success in the radar game will continue to govern thevalue of airpower as a tool of national security. Many ofAmerica’suniquepolicyoptionsdependuponit.WhenandiftheSA-20joinsIran’sairdefensenetwork,itwillmakethatnationaconsiderablytougherenvironmentforairattack,forexample.Alreadythereareregionsoftheworldwhereonlystealth aircraft can operate with a good chance of com-pletingthemission.

Infact,stealthaircraftwillhavetoworkharderthanever.Themajordifferencefrom1998to2010isthatdefenseplansnolongerenvisionanall-stealthfleet.TheAirForceandjointpartnerswilloperateamixtureoflegacy,conventionalfight-ersandbombersalongsidestealthaircraftevenastheF-35sarriveingreaternumbers.Theradargameof2020and2030willfeaturealotofassistsandthetacticsthatgoalongwiththat.

Rebecca Grant, DirectorMitchell Institute for Airpower Studies

September 2010


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Precision weapons and rapid targeting informationmean little if aircraft are unable to survive engagementswithenemyairdefenses.Inadditiontocostingthelivesofpi-lots,highlevelsofattritioncanultimatelyaffecttheoutcomeofthetheatercampaign.Oneofthemostcriticalfactorsindeterminingthesuccessofanairoperationissurvivability.Inthelastseveraldecades,thetermsurvivabilityhasbeenas-sociatedwithanalysisofhowlowobservablesandelectron-iccountermeasurescanhelpaircraftcarryouttheirmissionsin hostile airspace. Discussions of survivability immediatelybringtomindstealthaircraft, radar jamminganddebatesaboutthelatestSA-10threats.YetthequestforsurvivabilityisnotafadoftheColdWarorthehigh-technology1990s.Itsroots,anditsimportancetocombinedarmsoperations,gobacktothefirstuseofmilitaryaircraftinWorldWarI. Since the earliest days of military aviation, pilots andplannershavetakenadvantageofwhatever theiraircraftcanoffertoincreasetheoddsofsurvivability.Aircraftsurviv-abilitydependsonacomplexmixofdesign features,per-formance,missionplanning,andtactics.Theefforttomakeaircrafthardertoshootdownhasconsumedalargeshareofthebrainsandresourcesdedicatedtomilitaryaircraftde-signinthe20thcentury. Since the 1970s, the Department of Defense has fo-cusedspecialeffortonresearch,development,testing,andproductionofstealthaircraftthataredesignedtomake itharderforairdefensestoshootthemdown.Lowobservable(LO) technologyminimizesaircraft signature in radar, infra-red, visual, and acoustic portions of the electromagneticspectrum,creatingstealth.FutureplansfortheAirForceF-22andthetri-serviceJointStrikeFightercall for thenationtocontinuetoprocureadvanced,LOaircraftforthemilitaryofthe21stcentury. Thisessaytellsthestoryofhowthebalancebetweentheairattackerandairdefenderhasshiftedovertime,andhowtheradargamechangedthenatureofaircraftsurvivability.

Examining the evolution of this balance provides a betterunderstandingof thechoices facingmilitarycommandersanddefenseplannersastheyconsiderwhatformsofsurviv-abilitytechnologyareneededtopreservethedominanceofAmericanairpower. To begin with, the financial and strategic investmentin stealth aircraft is one that not everyone understands.Stealth technology was developed and tested in secret.F-117 stealth fighter squadrons were practicing night mis-sionsintheNevadadesertseveralyearsbeforetheAirForcepubliclyacknowledged theaircraft’sexistence.Evenafterthe F-117’s impressive performance in the 1991 Gulf War,an element of mystery and misunderstanding sometimessurrounds the operations of stealth aircraft. The F-117 andthe B-2 stealth bomber have the ability to complete andsurvivemissionsthatotheraircraftcannot.Still,forthemostpart, thegovernmenthasgivenonly themostcondensedandsuperficialexplanationsofwhattheselowobservableaircraftcandoandwhytheirmissionissoimportanttojointoperations.Inaddition,themechanicsofradarcrosssection(RCS)reductionandtheeffectoflowersignaturesintacticalscenariosareseldomdiscussed. This essay will reveal no technical secrets or surprises.Whatitwilldo,however,isexplainhowtheradargamebe-came a major factor in air combat; how LO technologygained the upper hand in the radar game; and how theoperational flexibility provided by low observable aircrafthasbecomepivotaltoeffectivejointairoperations.

The Origins of Aircraft Survivability Survivability—defined as the ability of the aircraft andaircrewtoaccomplishthemissionandreturnhome—hasal-waysbeenanimportantfactorindeterminingtheeffective-nessofairoperations.EarlyinWorldWarI,theuseofaviationforces incombat revealedthatsurvivabilityconsiderationswould influence mission effectiveness. Efforts to improve

INTRODUCTION

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survivability quickly began to influence aircraft design asspecializedaircrafttypesemergedby1915.ThewholeideaoftheSpadXIIIfighterplane,forexample,wastocombinemaximum speed and maneuverability to dominate aerialengagements.BomberssuchastheGermanGothaortheBritish Handley Page had a different mission and accord-inglydrewondifferentsurvivabilitymeasures.Theyreliedonself-defense guns and armor plating for survivability sincetheirextrarangeandpayloadprecludedmakingthemostofspeedandmaneuver. As aircraft survivability started to contribute to aircraftdesign,aircraftwerebecomingmoreimportantcontributorstocombinedoperationswithgroundforces.Aircrafthadtobeabletooperateoverenemylinestoreconnoiter,correctartilleryfire,andwardoffenemyairplanestryingtodothesame.By1918,aircraftwereanimportantelementofcom-bined arms operations because of their ability to extendthebattledeepbehindenemylines.“Theattackofgroundobjectivesinthezoneasfarbackoftheenemy’sfrontlinesas his divisional posts of command often yields importantresults,”notedaGeneralStaffreportin1919.“Thegreatmo-bilityandspeedofairplanesmakeitpossibletoutilizedaybombardmenttacticallytoinfluenceanactioninprogress,”continuedthereport.1

ThelastcampaignsofWorldWarIhintedthatairsuperi-oritywouldbenecessaryforthemosteffectivegroundop-erations,butWorldWarIImadeitanironlaw.However,theinventionofradarontheeveofWorldWarIIchangedtheaircraft survivabilityproblemcompletely. InWorldWar I, vi-sualdetection incleardaylightdidnotexceed rangesof10-15milesatbest.Eveninthelate1930s,defendersexpect-edtolistenandwatchforattackingaircraft. By 1940, radar could spot incoming aircraft 100 milesaway. Early detection gave defenders much more timeto organize their air defenses and to intercept attackingplanes. Radar height-finding assisted antiaircraft gunnersontheground.Primitiveairborneradarsetswereinstalledinnightfighters inthelateryearsofthewar.Theradargamehadbegun.Gainingairsuperiorityandthefreedomtoat-tacksurfacetargetswhileprotectingfriendlyarmiesrestedonsurmountingtheadvantagesthatradargavetoairde-fenses. The stakes of the radar game also affected com-binedarmsoperationsinalltheatersofthewar.Hitlercan-celedtheinvasionofBritainwhentheLuftwaffefailedtowinlocalair superiorityover theEnglishChannelcoast inSep-tember1940.TheAllieshingedtheirplansfortheNormandylandingsongainingcontroloftheairoverEuropeandex-ploitingitwitheffectiveairinterdiction.Therateatwhichair-powercouldaccomplishitsobjectivesthereforedependeddirectlyonsurvival ratesof thebombersattackingaircraftfactoriesandindustrialtargetsinFortressEurope.OncetheAllieswereashore,theyplannedforairpowertohelpoffsetthenumericalsuperiorityofGermangroundforces.

TheColdWarmadeaircraftsurvivabilityevenmorecom-plicated.AfterWWII,radartechnologyleaptaheadandair-craftdesignsstruggledtomaintainasurvivabilityedge.Bythe 1960s, radar dominated the air defense engagement.Longerrangedetectionradarsprovidedampleearlywarn-ing.Radar-controlledsurface-to-airmissiles(SAMs)improvedthespeedandaccuracyofattacksagainstaircraft. Intheair, more advanced radars and guided air-to-air missileschangedthenatureofaerialcombat.Conventionalperfor-manceimprovementsinspeed,altitudeceiling,maneuver-ability,andotherparameterspushedaheadbutcouldnotkeeppacewiththemostsophisticatedairdefenses.Ifradarmadeaircrafteasy to shootdown, theeffectivenessofairoperationswouldplummet. Asaresult,combataircrafthadtoincorporateaddition-alsurvivabilitymeasurestostayahead intheradargame.Electronic countermeasures (ECM) to radar were first em-ployedinWorldWarII.Researchinthe1950sand1960sledtomuchmoreadvancedcountermeasures thatdisruptedradar tracking by masking or distorting the radar return.Whenaircraftgotclosertotheairdefenses,however,theirradar reflections grew large enough to burn through theelectronicsmokescreenputinplacebyECM.

Winning the Modern Radar Game In this context, the prospect of designing combat air-craftthatdidnotreflectasmuchradarreturnwasanentic-ing possibility. British researchers in the 1940s hypothesizedabout foiling radardetection. Lowobservable technologythatreducedradarreturnwouldmakeitharderfordefend-ers to track and engage attacking aircraft because theywould not have as big an aircraft signature to follow. Lessradar return meant less time in jeopardy, or time in whichaircraftcouldbetrackedandfireduponbyotheraircraftorbyground-baseddefenses. However, coming up with an aircraft design that mini-mized radar returndependedonmany factors. Itwasnotuntiltheearly1970sthatthephysicalprinciplesofcontrollingradar returnwereunderstoodwellenough toapply themto aircraft design. Low observable technology was basedfirstonasophisticatedabilitytounderstandandpredictthebehaviorofradarwavesincontactwithanaircraft. Researchintospecialshapesandmaterialsmadebuild-inga lowobservableaircrafta reality.Theaimwasnot tomakeaircraftinvisible,buttoquantifyandminimizekeyar-easoftheaircraft’sradarreturn.Incorporatinglowobserv-ablesrequiredtrade-offsthatoftenappearedtogoagainstestablishedprinciplesofaerodynamicdesign.Theprimarymethodforreducingradarcrosssectionwastoshapetheaircraft’ssurfacesothatitdeflectedradarreturninpredict-ableways. Variationsintheanglefromwhichaircraftapproachedtheradar,andthefrequencyoftheradarsusedbythede-


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fenders,alsoaffectedtheradarreturnandrequiredchoicesabouthowtooptimizedesignsforthemostdangerouspartsof the cycle of detection, tracking, and engagement. AsRCS diminished, other factors became important corollar-ies,suchasreducingtheinfraredsignatureaswellasvisual,acoustic,andotherelectronicevidenceoftheaircraft’sap-proach. LO design offered immediate tactical benefits by cut-ting radardetection rangesanddegrading theefficiencyofsearchradars.Signaturereductionnowposedsubstantialproblemsforintegratedairdefenses(IADS)becauseitcoulddelayearlywarningdetectionanddiminishtheabilityoffirecontrolradarstoacquireandfireSAMsagainsttheattack-ingaircraft.

Aircraft Survivability and its Operational Impact Thepayoff for lowobservablescame fromdevelopinganaircraftthatcouldtackleeachstageoftheradargame.Lowobservablesofferedaway to regainsomeof thesur-priseelementofairattackandimprovetheoddsineachin-dividualengagement.Overall,LOaircraftwouldspendlesstimeinjeopardyfromairdefensesandstandamuchbetterchanceofcompletingthemissionandreturninghome. The tactical benefits of increased aircraft survivabilityopened up a wide range of options for air commanders.Most important, spending less time in jeopardy could re-duceattritionratesbyloweringtheprobabilityofaircraftbe-ingdetected, tracked,andengagedduring theirmissions.

Highly survivableaircraftcouldbe tasked toattackheav-ilydefendedtargetswithmuchlessrisk.Asaresult,desiredeffects—suchasdegradingenemyairdefenses—couldbeachieved in a shorter period of time. Critical targets thatmight have taken repeated raids from large packages ofconventionalaircraftcouldbedestroyedinasinglestrikebyamuchsmallernumberofF-117sabletopenetratecloseenoughtouselaser-guidedbombs(LGBs). The final section of this essay quantifies the effects ofsignature reduction in the tactical environment. Graphsshow how reduced signatures lower the time in jeopardy,andhowstealthdegradesdetectionbyearlywarningradarandsubsequent trackingandengagementbyfirecontrolradars.Threehypotheticalscenariosdisplaytheresultsoftheanalysis inhighand lowthreatenvironments.Variations foraltitudeandattackprofileareincluded.Ashortsectionalsodiscusses in general terms the potential synergy betweenlowobservablesandelectroniccountermeasures. SinceWorldWar II, the radargamebetweenattackersanddefendershasdeterminedwhowillcontroltheskies.Thewinneroftheradargamewillbeabletobringthemaneu-verandfirepowerofair forces tobearagainst theenemy.Forthe21stcentury,highlysurvivableaircraftwillcontributedirectlytoachievingjointforceobjectives.Theywilldothisbyshapingandcontrollingthebattlespacewherejointairandsurfaceforcesoperate.Theabilitytoprojectpowerwithefficientandeffectiveairoperationswilldependonwinningtheradargame.

The best way to understand the impact of radar isto lookbackat thefirstairwar.WorldWar Iduels in theairdefinedwhatittooktoprevailinaircombatandwhysurvivabilityratesintheaircomponentwereimportanttocombinedarmsoperations. Survivabilityinthemostbasicsensereferstotheabil-ityofanaircraftand itscrewtocarryout itsmissionandavoidbeingshotdown.Beforethedevelopmentofradar,controloftheaircenteredonaduellimitedtothefieldofviewofthehumaneye.AircombatinWorldWarIbeganwhenenemypilotsorgunnersonthegroundspottedat-tacking aircraft. To control the skies, the biplanes had tosurvivetheduel.Carryingoutmissionsandassistingforcesonthegrounddependedonensuringthatenoughaircraftandcrewswouldsurvivetofightinstrength,dayafterday. SurvivabilitywasasimportanttoairoperationsinWorldWarIas it istoday.Thetechnologyandtacticsweredif-ferent,butthebasicfeaturesoftheduelforcontroloftheskiesweremuchthesame.Theessentialelementsofthe

air-to-airengagementandtheproblemofground-basedairdefensetookclearshapebetween1914and1918.

Elements of the Duel AircombatinWorldWarIwasaduelbetweenattackersanddefendersforcontroloftheair.Toperformtheirmissions,aircraft had to survive encounters with hostile aircraft andwithenemygroundfire.Theirchanceofsurvivaldependedonthetechnicalabilitiesoftheaircraftandonthetacticalskillwithwhichtheywereemployed. Itmayseemstrangetospeakofthe“survivability”ofbi-planes with fabric wings and wooden two-bladed propel-lers.WorldWarIaircraftwereextremelyvulnerabletoclose-inattack.France,Germany,Britain,andotherwarringnationsconsumedaircraftatstaggeringrates,runningthroughsup-pliesoftensofthousandsofmachines inthecourseofthewar.Accidents,poormaintenance,dirt runways,andevenexposuretotherainandwindclaimedaheavytoll.Pilotin-experiencealsocontributedtolossrates.

SURVIVABILITY BEFORE RADAR

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However,WorldWarI’sairwarsketchedoutelementsoftheduelforsurvivabilitythatwouldreappearinaircombatinWorldWarII,Korea,Vietnam,andDesertStorm.Byfocus-ingonhowthesurvivabilityduelemergedinWorldWarI,itispossibletosetabaselineforunderstandinghowevolutionintechnologyhaschangedthesurvivabilitydueltoday. EncountersbetweenattackersanddefendersinWorldWarIoutlinedthreepartstotheirduel:detection,engage-ment,andprobabilityofkill.Detection refers to the taskofspotting and tracking enemy aircraft. Engagement repre-sents a defending fighter attempting to close in during adogfight,orground-basedairdefensestrackingandaimingat incomingaircraft.Probabilityofkill involvesanumberoffactors. In its simplest form, itassumes theaircraft ishit,butthechanceofdestroyingtheaircraftdependsonthenatureandextentofthedamagesustained. Thedefenderattemptstocompleteeachstage.With-outdetection,noengagementispossible.Withoutengage-ment, there isnoprobabilityof kill.On theotherhand, theattacker’staskistothwartthedefenderateachstage.Ide-ally, theattackerwouldenjoycompletesurpriseandarriveoverthetargetareaundetected.Ifdetected,pilotsevadeorprepareforengagement.Ifengaged,theyseektodestroyoravoidenemyaircraftandtododgeenemysurfacefire.Iftheaircraftishit,probabilityofkillwoulddependonthenatureandextentofthedamage. Thedistinctionsbetweenthethreephasesareartificialfromtheaircrew’sperspectivebecauseeachstageblends

into the next. However, analyzingeachstagehelpstoillustratethepro-cessofachievingsurvivability.

Detection Thefirst task in theduelwas tofindthe enemy, and inWorldWar I, therewas little that technology could dotoassist in theprocess.Detectionde-pendedalmostexclusivelyonthehu-maneye.Defendersintheairoronthegroundhadtoseetheairplane,hearit,orperhapsbeshotatbyit,inorderto know itwas there. In thedaysbe-fore radar,noothermeansexisted todetect and track enemy aircraft. TheWorldWarIaviatordidnotevenhaveacockpit radio to report locationsofenemyaircraft. Defenders constantly struggled togain early warning of air attack. Air-planes could often be heard beforetheywereseen.Pheasants,thoughttohave acute hearing, were placed atFrench listening posts to warn of ap-proaching aircraft. In England, audio

detectionformedpartoftheairdefensescreenaroundLon-don. Bothsidesmountedfrequentpatrolstoseekoutandde-stroyenemyaircraft.Whentroopsonthelinespottedaircraft,reports were relayed by telephone to the airfields. Airfieldcommandersmightlaunchplanesintimetointercepttheat-tackers.ThefirsttwoAmericankillsofthewarcamefrompilotsscrambledtointerceptGermanaircraftpatrollingoverfriendlylines. Oncetheaviatorcouldseehisopponent,bothwerevul-nerabletotheformidableshort-rangetrackingcapabilitiesofthehumaneye.Theshortrangeofvisualdetectionplacedapremiumontheelementofsurprise.“Thedecidingelementinaerialcombatisusuallysurprise,”explainedanairserviceman-ualin1919,sothe“enemywillemployallmeansathisdisposaltoconcealhisapproach.”2Inaircombat,aircraftmighthavetoclosetowithin50yardsforagoodshotattheopponent.

Deceiving the Eye A fewmeansexisted to thwartopticaldetection.Hid-inginclouds,attackingoutofthesun,and,mostofall,ap-proachingfromaboveandbehindtheaircraftdelayedop-tical detection. Camouflage paint schemes blended wingsurfacesintothecolorsoftheterrainbelow. However,thesinglemosteffectivemeasureagainsttheenemy’sability todetectand interceptwastoflyatnight.WorldWarIaircraftcouldoperatealmostatwillundercover


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ofdarkness.Onabrightmoonlitnightenemyaircraftcouldbeseenatjust500-600yards;instarlight,theirdarkshadowsmaterializedat200yardsorless.Asonescholarsummarized:

“There were several ways to meet the threat posed by the fighter: One was to increase the bomber’s capability to defend itself; another was formation flying, which allowed planes to put up a collective defense; and a third was to have the bombers escorted by fighting craft of one’s own. But the most effective response for planes with long‑distance missions was simply to carry out those missions at night. The enemy fighter, so formidable by day, did not even attempt night interceptions until the end of the war.”3

Bothsidestookadvantageofthecloakofdarknesstoreach deeper into enemy territory in search of iron works,concentrationpoints,supplydepots, railroadsandother lu-crativetargets.Basesandtownsalongthefrontblackedouttheirlights.Onnightswithbrightmoonlight,Germanbombersroutinely attacked French border towns such as Nancy. Bylate1917,mostofthecitywasevacuatedand“caveshadbeenbuiltalongthestreetsinwhichpassers-bycouldtakerefuge in case the airplanes came,” Billy Mitchell noted.4

Searchlights and anti-aircraft guns did little to stop the at-tacks.Ononemoonlitnight,GermanGothabombersscoredtwodirecthitsonanammunitionfactoryinNancy,knockingit out of production for the remainder of the war. Describ-inganothernightraidnearhishotel,Mitchellwrotethat“theanti-aircraftgunswerefiringatthesoundoftheairplanesasmuchasanythingelse.”5

Thelackoflongrangedetectionlinkedtoanintegratedcommandandcontrolsystemmeantthatforthemostpart,airoperationsinWorldWarIdidnotencounterwell-or-ganized antiaircraft gun defenses.Enemyantiaircraftdefensescouldhesevere at times and non-existent atother times. For the attacker, the sur-vivability duel with ground defenseswas one over which pilots felt theywerethemasters. “No,wehadlittlerespectfortheantiaircraftgun—unlessitwasprotect-ing a balloon,” wrote Eddie Ricken-backer.Pointdefensesaroundknowntargets like balloon emplacementscould be lethal because they ben-efited from many of the advantagesthatwouldbe featured in integratedair defenses decades later. Balloondefense crews knew their“sausages”were high value targets that wouldattract air attacks. Because balloons

operated at fixed altitudes as well as fixed locations, gun-nersprotectingthemcouldaimatexpectedattackroutes.Theycouldalsopredictthealtitudeoftheattackandsetthefusesoftheantiaircraftartilleryaccordingly.AsRickenbackerdescribedit:

“If the balloon was two thousand feet up, then any aircraft attacking it must also be at or near the same altitude. When we came in to attack a balloon, therefore, we flew through a curtain of shells exploding at our precise altitude. We had to fly at that altitude for several seconds, for it took a long burst to ignite the gas. ... After the attack it was necessary to fly out through the wall of Archie on the other side.”

Finally,Rickenbackeradded,“Balloonswereofsuchmili-taryimportancethat,frequently,flightsofFokkerswouldbehoveringabovethem,hidingupthereinthesun.”6

Pilotreportsfromairoperationsin1918documentedev-erything from heavy but inaccurate antiaircraft fire all thewaytothetarget,toverylightornon-existentfire.Still,Rick-enbacker’sdescriptionforeshadowedthelethalairdefenseenvironmentofWorldWarIIandbeyond,whenthelimitsofoptical detection would be overcome and aircraft wouldlosemuchoftheiredgeinsurpriseattack.

The Engagement: Designing Aircraft to Survive With advance warning and detection limited to therangeofthehumaneye,thekeytosurvivabilityinWorldWarIwastoprevailintheengagementphase.Structuraldesignfeatureswereparamount. The warring nations entered the conflict with general

13


purposeaircraftintendedmainlyforreconnaissance.Buttheairwarquicklyplacedapremiumonaircraftdesigned forspecializedmissions.Inadogfight,speed,rateofclimb,andmaneuverability could significantly influence the outcome.Asoneaviatorlaterwrote:

“The war has shown that there is no universal or multiple pur‑pose plane, which can be used for pursuit, reconnaissance and bombing work. Each particular work calls for a different type of plane, specializing either in speed, maneuverability, climbing ability, carrying capacity, or long distance range. In order to embody one of these characteristics in a plane, others must be sacrificed.”7

By1915,thenewaircraftdesignsreflecteddistinctmis-sion requirements. Survivability features were tailored toeachtype. Forexample,thewholeideaofapursuitaircraft—afight-er,intoday’sterms—wastoseekoutandengageenemyair-craft,andshootthemdown.Speedandperformancegaveaskilledpilotanadvantageoverhisopponents.TheBritishcheeredthearrivaloftheirfastandagileSopwithCamelsin1917.TheGermanFokkerDVIIwasoneofthebestmachinesofthewarbecauseofitsincreasedspeed,maneuverability,andperformance.In1918,aFrenchpilotwrote:“Daysofhighspirits!WehavereceivedSpads!Nowwe’refinallygoingtoshowtheFritzesaboutspeedandmaneuverability.”8Ameri-canace-to-beEddieRickenbackermadeaspecial trip toParisthatsummertopickuphisnewFrench-builtSpadXIII. Where mission requirements diversified, so did surviv-ability features. Some pursuit aircraft, such as Britain’s Sop-withSalamander,werebuiltasarmoredtrench-fighters.Ma-chinegunspointedthroughthefloorofthecockpitand640poundsofarmorplatingprotectedthefuselagefromriflefireataltitudesaslowas150feet.9

Inanentirelydifferentclass,observationaircraftcarriedtwo pilots and more guns because they could not rely onrawspeedintheirdangerousmissionsoverthelines.Experi-encedFrenchobservationpilotscounseledAmericantrain-eesaboutthedangersfromthefasterenemyaircraftpursu-ingthem:“Yourplaneswillbeslower,lessmaneuverable.Donothesitatetorun.”10Additionalself-defensefeaturessuitedtheirmissionofcrisscrossingandlingeringoverenemylinesatloweraltitudes.Therearobserverwasarmedwithamachinegun.DedicateddesignssuchastheSalmsonincorporatedamoreruggedairframeandarmorplating. Self-defense firepower was also the prime ingredientin survivability for thebiggerandslowerbombardmentair-craft.Asonepilotputit,“Inasmuchasnobombingplanecanhopetorunawayfrompursuitplanes,itsdefensivepowerliesinthestrengthoftheformation.”11

AHandleyPagebomberclocked95mph.ThiswasnomatchforaSpadXIII,stapleofthelateryearsofthewar,which

couldreach120mph.Pursuittacticsofthedayfrownedonescortingthebombers.Instead,pursuitgroupsmetbombersovertheirtargetstoengageenemyaircraft,andagainwhenthebomberformationcrossedovertofriendlylines.Bombersspentmostoftheirmissionsinjeopardywithonlyamachinegunnerseatedbehindthepilottoputupanarcofdefen-sivefire.“Agoodformationofbi-placemachinescanfightoffdoublethenumberofpursuitplanes,”contendedabomberpilotafterthewar.12

Probability of Kill Thefinalphaseofthesurvivabilityduelconsistedofthelikelihoodorprobabilitythatshotsfiredduringtheengage-mentwoulddisableanddown theaircraft.Analystswouldlatertermthis“probabilityofkill.”Dependingonthesystemsinvolved,theprobabilityofkilldependedonanynumberofcomplexvariables. Aircrews sought to control these variables where pos-siblejustastheydidinallphasesoftheduel.Throughtacticsandpersonalpreferences,WorldWarIpilotsstrovetoprotectthemselveswhileensuringthatshotsfiredwouldbelikelytohittheirmark.Someaviatorshadtheirmechanicshand-loadammunition belts to help prevent the guns from jammingduringadogfight. Once hit, structural factors could determine whetheror not the aircraft survived to return to base. Bullets mighthitoil lines. Steepdivesmight tear fabricoffwings.On theother hand, armor plating could protect the pilot and thestructural integrity of the aircraft. Near-misses became thematerial for legendsof thefirstairwar.At thesametime, iftheaircraftwasdetected,engaged,andfiredupon,designfactorsmightstillsaveit. Eachstageoftheduelforsurvivabilitycontaineditsowncomplexvariables.Solvingthemandmaintainingtheopera-tionalstrengthoftheairarmwasanimportanttaskbecauseofthegrowingroleofairincombinedarmsoperations.

Survivability and the Air Campaign AircraftsurvivabilitybecameimportantinWorldWarInotbecauseofthelegendaryexploitsitproduced,butbecauseeffectiveairattacksbecameavaluableassettocombinedarmsoperations.By1918,controloftheairhadbecomeoneofthedesiredprerequisitesforgroundoffensives.Establishingtemporarycontroloftheairenabledaviationunitstodriveoffenemyaircraftanddenytheminformationabouttheof-fensiveasitdeveloped.Controloftheairalsoallowedpursuitaircraftandbomberstoconductgroundattacksinsupportof army offensives attempting to attack and maneuver tobreakthedeadlystalemateofthewar.TheairwarofWorldWarImarkedthebeginningofatrendinwhichtheaircom-ponentswouldgrowtohaveashapinginfluenceoverthe-aterplansandoperations. The air component’s ability to play an effective role


14

hingedonsurvivability.Lossratesdeterminedhowmanyair-craftandcrewswouldbeavailableforsustainedoperations.Thelossofevenafewaircraftperdaycoulddebilitatetheairarmquickly.Thechartbelowplotsthemathematicalrateofattritionofaforcethatbeginswith1,000aircraft,eachflyingtwosortiesperday. Losing two percent of the force per day would resultin the lossofalmost 70percentof the1,000aircraft in just30days.Withoutreplacements,thenumberofsortiesflownwoulddropbyalmost50percent,greatly reducing theef-fectivenessofairoperations.EvenatWorldWarIproductionrates, no commander could afford sustained attrition andhopetoremainaneffectiveforce. Air tactics and operational employment conceptssoughttomaximizesurvivabilityinordertokeepupeffective-ness.Survivabilityconsiderationsdirectlyinfluencedemploy-mentconceptssuchasflyinginformations.“Theemploymentofa largenumberofpursuitairplanes inattackinggroundobjectivesincreasesthesafetyoftheoperationsbymultiply-ing the targetsatwhich theenemymust shoot,” reasonedMitchell.Asapostwarmanualinstructed,“Bombingandma-chine gunning of ground targets can only be carried outwhenair supremacy isattained.”Air supremacyhadtobe“temporaryat least”ortheloss inmachineswouldexceedthedamagedonetotheenemy.Anexperiencedpilotaloneoverenemylinesmightsurvive.However,thelimitednatureofwhattheloneaircraftcouldaccomplishmeantthatitwasnotworththeriskofthepilot’slife.13

Dailyattritionmatteredespeciallyasseniorcommand-

ersbegantodependonairoperationsasaroutinepartofcombined arms operations. Under the right conditions, airattackscouldbe surprisinglyeffectiveatdisruptingenemyforcesbehindthelines.Idealtargetsforairattackwereforc-es in concentration, either retreating from or marching uptothefrontlines,preferablyintheearlieststagesofamajoroffensive.

“When an offensive is under way large bodies of troops, cav‑alry and transport are being brought up to the line. These targets are large enough to spot from some distance in the air. Fire can be directed on the group and a great amount of material damage as well as moral damage to the enemy can be done.”14

Every major offensive in 1918 used aviation both toharassandstrikeattheenemy’sreservesandsupplies.TheGermans used airpower to sharpen their offensive in thespringof 1918,andby that fall, theAllieswereemployingmass airpower in conjunction with their own efforts to rollbacktheexhaustedGermanlines.Inthefallof1918,atSt.Mihiel,PershinginstructedMitchelltoassembleacoalitionforce to keep German aircraft back from the ground of-fensive and to assist by attacking German forces as theyattemptedtoretreat.Aslongasconditionsforsurvivabilitycouldbemet, theairarmcouldmakevaluablecontribu-tionstocombinedoperations.

The Interwar Years AircraftinWorldWarIusuallycouldnotbedetect-ed in time to organize and integrate air defenses.Thatmeantthatthesurvivabilitydueldependedonspeed, maneuverability, armament, and other ad-vantages in the engagement between aircraft orwithground-baseddefenses. Aviation design in 1920s and 1930s still sought tomaster the duel between attackers and defendersbydevelopingfaster,moreruggedaircraftasbettertechnology emerged. For a long time, defense sys-temsoffered fewadvancesoverWorldWar I in theproblemofdetectingandtrackingaircraft.BoththeGermansandtheBritishdevelopedlisteningdevicestohearincomingbombersatlongrange. Air tactics and doctrine between the wars con-tinued to assume that aircraft would be detectedonlybytheenemy’seyesandears.Surprisecouldstillbe achieved. Cities and armies alike would remainhighlyvulnerabletosurpriseairattack,especiallybylong-rangebombers. In the 1930s, aviation technology started to yieldsignificant advances that appeared to decreasethe vulnerability of aircraft to detection. With theirlong range, speedy mono-wing designs and guns,

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InWorldWar II as never before, the fortunes of airpowerwouldplayanimportantroleinthetheatermilitarystrategyforeachbelligerent.WorldWarIIaviatorsflewinanairdefenseen-vironmentmorelethalandconsistentthananythingthatWorldWarIaviatorshadfoundontheWesternfront.Thebattleforairsuperioritydominatedoperational-levelplansboth forairandforcombinedarmsoperationsacrosstheEuropeantheaterofwar.Controloftheairwasbecomingaprerequisiteforsuccessinmajorgroundoperations. Forthefirsttime,thesurvivabilityandeffectivenessoftheair component was a major weight in the balance of com-bined-armsoperations.Butneithertheaircraftnorthedoctrineoftheinterwaryearswerereadyforthenextphaseofthesurviv-abilityduel. Inthesummerof1938,theGermancorporationTelefunken

wastestingareliableradardevice.Telefunken’sheadofdevel-opment,Prof.Dr.WilhelmRunge,wasreadytodemonstrateitfortheLuftwaffe.Gen.ErnstUdet,aWorldWarIace,wasthenserv-ingasQuartermasterGeneraloftheLuftwaffe,andcameouttoseethetest.Rungerecalled:

“When I explained that it could be used to cover a 50 km area, and that in spite of fog, or at night, it would locate an aircraft easily within that range, his reaction was astonishing. ‘Good God! If you introduce that thing you’ll take all the fun out of flying!’ “16

Udetcorrectlysensedthatradarearlywarningwouldstripattackingaircraftoftheelementofsurpriseandset inmotiona grueling duel between attackers and defenders. The radar

thebomberswereexpectedtobehighlysurvivable.Theycould attack with speed and surprise. Many new pursuitaircraft designs clung to biplane structures for extra ma-neuverability. But the drag from the wing spars of the bi-plane fighters slowed them down. Bombers of the 1920sandearly1930scouldoftenoutrunpursuitaircraft.AsBritishPrimeMinisterStanleyBaldwinsaidin1932:

“I think it is well for the man in the street to realize there is no power on earth that can protect him from bombing. ... The bomber will always get through … .”

Suchthinkingreflectedtherealitythatamassformationcouldneitherbeheardnorseensoonenoughforfightersandantiaircraftgunstodestroymuchofit.Amoreexpertwitness,CarlSpaatz,hadwrittentoacolleaguein1931thatbombersflyingbelow15,000feetwouldneedpursuitaircraftprotection.

However,“ataltitudesabove15,000feetobservationfromthegroundbecomesdifficult,” Spaatznoted,“andabove20,000feet bombardment airplanes can make deep penetrationswithoutpursuitprotection.”15TheanalysisbySpaatzwasbasedonrealisticassumptionsforthetime. Toanobserver in themid- to late-1930s, the survivabilityduelcontainedmuchthesameelementsithadin1918.Detec-tionwasdifficult,givingtheattackertheadvantageofsurprise.Toshootdownanattackingaircraft,otheraircraftorguncrewshadtoprevailintheengagementandassureaprobabilityofkill,allinarelativelyshortspaceoftime. But the survivability duel was about to change beyondrecognition.InBritain,by1937,scientistshaddevelopedade-vicetodetectaircraftatrangesfarbeyondthatofthehumaneye.Theeffectonairtacticsandoperational-levelplanswouldshapemostofthedecisivecampaignsofWorldWarIIandthedynamicsofaircombatfortheremainderofthecentury.

THE RADAR GAME BEGINS


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gameforeverchangedaircombattactics,anditseffectonsur-vivabilityratesrapidlycametodominateoperationalplansforairwarfare. Radartookairmenbysurprise.Whilethebasicprinci-plesbehindradarwaveshadbeenunderstoodbyatleastafewscientistsforyears,itwasnotuntilthemid-1930sthatintensiveresearchsolvedseveralimportanttechnicalchal-lenges. In1904, justoneyearafter thefirst flightatKittyHawk,aGermanengineernamedChristianHulsmeyerinventedthefirsttelemobiloscope.Thedevicegeneratedradiowavestodetectshipsatrangesofafewmiles.Hulsmeyerobtainedapatentforhisinventionbutfailedtofindcustomersforhisdevice,andthepatentslapsed.But30yearslater,in1934,researchersinAmer-ica, Britain, France, Italy, Germany, and the Soviet Union wereatworkonradardetectionprojects.TheLeningradElectrophys-icsInstitutehadadevicetodetectaircrafttwomilesaway.TheFrench luxury linerNormandieboastedamicrowaveobstacledetector. The British brought together a research team that hadthefirstsuccessinusingradiowavestofindtherange,azimuth,andheightofanaircraft.Inthesummerof1935,RobertWatson-Watt’sexperimentsatOrfordnessdetectedandtrackedaircraftatarangeof40milesandmeasuredheighttowithin1,000feet.RadioDirectionAndRanging,betterknownbyitsnicknamera-dar,hadbeenborn.

How Radar Works Why were aircraft so vulnerable to radar detection? Inshort,forallthereasonsthatincreasedtheiraerodynamicquali-tiesandperformance.Metalskins,largeverticalcontrolsurfac-es,bigpowerfulengineswithmassivepropellerblades:All thefeaturesthatmadetheGermanMe-109MesserschmittandtheAmericanBoeingB-17bomberfasterandmorereli-ablealsomadethemexcellentradarreflectors. Radar detects scattered radiation from ob-jects,and isparticularlygoodatdetectinghighlyreflectivemetallicobjectsagainsta less reflectivebackgroundsuchastheseaorthesky.Wavesaregeneratedandtransmittedintheradio-frequencypartof theelectro-magnetic spectrum.The radarreceiverthencapturesthereflectionofthewavesastheyareencounteredandaretransmittedbackfrom objects of interest. Since the speed of radiowavepropagationfromtheradarisaknowncon-stant, radar systems can determine the position,velocity,andothercharacteristicsofanobjectbyanalysisofveryhighfrequencyradiowavesreflect-edfromitssurfaces. Hulsmeyer was readily able to develop andpatentaradardetectiondevicein1904becausetheprinciplesofelectromagneticwaveshadbeenthoroughlyresearchedinthelatterpartofthe19th

century. An electromagnetic wave consists of two parts: anelectricfieldandamagneticfield.Thesefieldsrapidlyfluctuateinstrength, risingtoapeak, fallingawaytozero, thenrisingtoapeakagain.Thisprocess repeats itselfoverandoveras thewavetravels(propagates) inadirectionatrightanglestotheelectricandmagneticfields.Wavesaremeasured in termsoffrequencyandwavelength. The frequency of a wave equals the number of crestsortroughsthatpassagivenfixedpointperunitoftime.Wavefrequenciesaremeasured in termsofkilohertz (onethousandcyclespersecond),megahertz(onemillioncyclespersecond),andgigahertz(onebillioncyclespersecond).Wavelength,thedistancebetweentwosuccessivepeaksofthewave,isdirectlyrelatedtothephysicalsizeoftheantenna. Increasingthefre-quencyofawavedecreasesthewavelength. British experiments with the first operational detection ofaircraftessentially sought to swapanairplane fora radioan-tennatotransmitbackasignal.Tograspthisprocess,itisimpor-tant tounderstand that radarenergy strikinganaircraftdoesnotsimplybounceoffthetargetinthewaythataballbounceswhen itstrikesawall.Whenaradarwavemeetsanelectricalconductor,suchasawire,itcreateswithinthatelectricalcon-ductorelectromagneticcurrentsatthesamefrequencyasthewave.Theelectricandmagneticfieldsthatformthewavearepolarizedandretransmitted.Thisretransmissionisthesamethingthatoccurswhenlistenerstuneintoradiosignalsusingaradioreceiverandantenna. Panel1showshowelectromagneticwavesfromadistanttransmitterattheradiostationinduceasmallcurrentwithintheantennaoftheradio.Theradioreceiveramplifies itandtrans-mitsitthroughthespeakers. Panel2showsthatwhenaradarwavehitsanaircraft,itinduceswithintheaircraftelectricandmagneticcurrents.

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Thesecurrentsthencreatenewelectro-magnetic waves, depicted in Panel 3,thatareemittedfromtheaircraftinvari-ousdirectionsand,dependingonwheretheystriketheaircraft,areseenbythera-darreceiverasreflectedechoes.Theseechoesaresignificantlyweakerthantheoriginal electromagnetic waves trans-mittedbytheradar. Thefirst testofBritish radar—theDa-ventry Experiment—was conducted onFeb.26,1935.Inessence,theDaventryex-periment treated the aircraft like a flyingantenna that could transmit waves backto the receiver on the ground for detec-tion. Watson-Watt’s team carefully cali-brated the wavelength of the transmit-tedsignalsothattheaircraftwingwouldgenerate a strong return. British scientistsknew from their work on radio antennaethat a wire whose length correspondedtohalfthewavelengthoftheradiosignalwouldre-radiatestrongly.Assumingthatthewingofanaircraftwouldbehaveinthesamemanner,theengineerssettledonafrequencywhosewavelengthwouldbetwicethatofthetypi-calGermanbomber,orabout25meters(80feet).Thustheen-gineerschose49-meterwavelengthsignalsat6MHz. ABBCradiostationservedasacrudetransmitterissuingaconstantbeamatawavelengthof49meters.AHeyfordbomb-er,flyingat100mphand10,000feet,eightmilesdistant,crossedthe continuous beam and briefly transmitted reflected radiowavesbacktothereceiver. One initial problem withWatson-Watt’s Daventry contin-uous-wave radar system was that outgoing signals interferedwithincomingsignals.ByJune1935,theBritishhaddevelopedapulsedtransmitter,whichsentoutpulsesofelectromagneticenergy so that the receiver could distinguish among echoes.Pulseradar,nowstandard,usesasingleantennafortransmissionandreception.Pulse radarsendsahigh-powerburstof radia-tionthenwaitsforthereturnsignal.Theintervalbetweenpulsesmatchesthetimeforawavetoreachatargetatagivendis-tance.Thisprocesstakesplacethousandsoftimespersecondinatypicalpulseradar. Uponseeingtheblipappearonacathoderaytube,Wat-son-Watt reportedlycommentedthatBritainhadbecomeanislandoncemore.Theprospectofdetectingaircraftenroutetoattackopenedupprofoundpossibilitiesforairdefenders.Britainrushedtocapitalizeonthem. ByApril1937,experimentalstationshaddetectedplanesatarangeof100miles,andbyAugust,BritainhadactivateditsfirstthreeChainHomeradarstationsatBawdsey,Canewdown,andDover.

Radar Early Warning: The Battle of Britain TheairplanesrollingofffactoryassemblylinesontheeveofWorldWarIIwerepoorlypreparedtocopewithradaranditsconsequences.Planesflewfaster,higher,andfarther,withgreat-ersafetyandreliability,thantheyhadinWorldWarI.Theyhadsturdymetalskinsandbigenginesthatgeneratedthousandsofhorsepower.However,intheradargame,aerodynamicadvan-tages also contributed to the prospect of being detected, inadvance,byradar.Theradargamestrippedawaytheelementofsurprisethatdatedfromthedaysofvisualandacousticde-tection.Itaddedanewandcomplexrealmofvulnerabilityandopportunitytotheaerialduelandmadethedetectionstageoftheduelcriticallyimportant. Britishairdefenseswerethefirsttoscorebigbenefitsfromtheradargame.TheChainHomeradarsystemnowringedtheairapproachestotheisland. DuringtheBattleofBritainin1940,radarearlywarningal-lowedtheRAFtodirecttheirscarcefighterstoattackincomingGerman formations instead of patrolling assigned air defensesectors.InearlyAugust1940theLuftwaffestillbelievedthatRAFfighters were“controlled from the ground” and“tied to theirrespectivegroundstationsandaretherebyrestrictedinmobil-ity....Consequently,theassemblyofstrongfighterforcesatde-terminedpointsandat shortnotice isnot toheexpected.” 17

TheLuftwaffejudgedthattheRAFwasalreadyweakenedandcouldbedefeatedindaylightoperationsbypiercingthinsec-tordefenseswithstrongerformationsastheRAFattemptedtopatroleverysectorofthesoutheastcoast. Instead, the RAF found that radar early warning madefighters effective in a way that had not been imagined. The


18

ChainHomeradarearlywarningsystemdetectedapproachingaircraftouttoabout100miles.Radarinterceptspassedtosec-toroperationscentersalertedtheRAFgroundcontrollerswhentheGermanstookofffromtheairfieldsacrosstheChannelandformedupforattack.EarlywarninggavetheRAFamuchbet-terestimateof theheadingandnumbersofGermanaircraft.Updatedestimatesof thebearingof the incomingformationscluedintheRAFastotheobjectivesoftheattack.Missiondi-rectorsonthegroundcouldthenalertfighterstoscramble,orevenbetter,vectorfightersalreadyonpatrolandataltitudetointercepttheGermanformations. Admittedly, theLuftwaffe’sstrategycountedonbring-ing the RAF up to fight. But the RAF’s advantage in beingabletomassfortheencountersrobbedtheGermansofsur-priseanditsadvantages,suchasselectionofthetimeandlocationforaerialengagement.Radarhelpedcompensatefor inferiority in numbers in a way that would never havebeenpossiblehadtheRAFtriedthekindofsectordefensetheGermansanticipated. TheBattleofBritainshowedthatearlywarninggavede-fendingfightersthetimeandflexibilitytomassforintercepts.FortheRAF,theflexibilityprovidedbyradarstoletheadvantagesofmassfromtheLuftwaffe.Bymid-September1940,theGermansdidnotbelievetheyhadestablishedevenlocalairsuperiorityover the southeast of England and the Channel coast. With-outairsuperiorityintheseareas,theamphibiousinvasionplancode-namedOperationSealioncouldnotbemounted.Inthe

end,thefailuretogainairsuperioritycompelledtheGermanstopostponetheinvasionofBritainindefinitely.

Survivability and Air Operations Thesurvivabilityduelnowdependedmuchmoreonmak-inguseofearlywarninganddetection. JustasearlywarningradargavetheBritishanedgeintheBattleofBritain,itgavetheGermansanadvantagewhentheAlliesbegandeeppenetra-tionattacksontargetsinNazi-heldEurope. Bombersurvivabilitybecamethefirstkeytooffensiveac-tionintheairandtothedesignoftheEuropeantheatercam-paign. What is seldom realized is that the Eighth Air Force’smost legendary—and most costly—missions in 1943 focusedonwinningcontroloftheair.EighthAirForce’sobjectiveswerenotbasedprimarilyonastrategiccampaignthatdisregardedcombinedarmsstrategyintheEuropeanTheaterofOperations(ETO.) Instead, theyhadasingleoverridingaim: tochoke theLuftwaffe.Allotherprioritiesweresubordinate. In June 1943, the Combined Chiefs of Staff ordered thebombing campaign to concentrate on the German aircraftindustry. InthePointblankdirective,theycalledontheairarmto“checkthegrowthandreducethestrengthofthedayandnightfighterforces.”The“firstpriorityoftheBritishandAmericanbombersbasedintheUnitedKingdomistobeaccordedtotheattackofGermanfighterforcesandtheindustryonwhichtheydepend.”AsanArmyAirForcesreportlaterputit,“thesuccessoffuturestrategiccampaignsandinvasionofthecontinentde-

pendedoneliminatingtheLuftwaffe.”18

GermanearlywarningradarsliketheFreyaringedthecoastofNazi-occupiedEu-rope. Radar tracking allowed the Germanstoorganizeanairdefensethatwoulddirectfightersatforwardbasestoengagebomberformations.Thedeeper thebombershad toflytoreachtheirtargets,themoretimeGer-man fighters would have to engage them.This greatly increased what can be termedthe time in jeopardy for attacking bomberformations.Timeinjeopardyisdefinedinthisstudyas theperiodduringwhichdefenderscould track and engage attacking aircraft.Instead of being intercepted only over thetarget area, bombers might be repeatedlydetectedandengagedontheirroutetothetargetandback. The Allies rapidly discovered thatattacks on cities deep in Europe exposedthe formations to repeated engagementsstagedoutofthemanyLuftwaffebasesfromtheFrenchandDutchcoasts to the interior.Radartrackingmadethispossiblebyalertingfightersandleadingthemtothegeneral lo-cationofthebomberformations.

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ThePointblankdirectivepresentedAlliedbomberswithsignificantsurvivabilityproblemsbecause German air defenses were muchmoreeffectivewith theuseof radar.TheonlywaytostrikeattheLuftwaffewastohititsfight-erproduction.Germanfighterproductionwasconcentratedatafewmainindustrialcenters. EighthAirForcedecidedtopairaraidonRegensburg, which produced 500 of the esti-mated650Me-109sthatrolledofftheassemblylineseachmonth,withastrikeonSchweinfurt’sball-bearingsindustry. The Regensburg force left the coast ofEnglandat0935onAug.17,1943.Germanearlywarning radars firstdetected thebomber for-mationsastheyclimbedtoaltitudeandformedupoverEngland.At17,000feet,theformationwasalreadywithinrangeoftheGermanradarscreenwithits150-milerange.GermanairfieldsfromParistoDenmarkalertedfighterstointer-ceptthebomberstreams. Enroutetothetarget,thebombersspentnearly all of the next three hours in jeopardyfrom fighter intercepts along their radar-tracked flight path.Ground controllers passed the location and bearing of thebomber formations to the fighters. German fighters acquiredthebombersvisuallyandusedelectricgunsightstotrackandattack them.As theB-17sapproached the target,antiaircraftguns,alsocuedandvectoredbyradar,putupadensecurtainof88mmflak.LeadformationsbombedRegensburgat1143.TheSchweinfurt force,delayedby fog,departedEnglandat1314andspentthenextfourhoursinjeopardy,bombingat1457. FortheB-17,theengagementphaseofthedueldepend-edontheformation’sdefensivefirepowerandlater,onescortfighterstodefendthebombersagainstengagementbyenemyfighters.Whentheformationreachedthetargetarea,morede-fensesawaited. Bombers had to fly directly over their targets to releasetheir bomb loads. Some targets, like the oil refinery at Leuna,wereringedwithover700antiaircraftartillery(AAA)batteries.

Ground-basedflakbatteriesmadeuseofradarfortargettrackingandheightfinding.From1941,Germanunitsintroducedgunlaying radar. Ground-based fire control radars aided theGerman antiaircraft guns in determining height and bearing.Withaccurateheightestimates,fusesonartilleryshellscouldbesettoexplodenearerthebomberformations.Overthecourseof the war, German air defenses also experimented with ra-dar-guidedflakrockets. The Regensburg force flew on to land at bases in NorthAfrica.TheroutewaspickedtoavoidAAAandfightersonthereturn route.TheSchweinfurt force returned toEnglandalongthe same route, spendinganother threehours in jeopardy.Alltold, Eighth Air Force lost 16 percent of the dispatched forcethatday. In thefinalanalysis, the ruggeddesignof theB-17oftenhelpedthebomberanditscrewsurviveattackbydecreasingthe probability of kill. The chart below diagrams a typical en-


20

gagementagainstunescortedbombers.Ondeepraids,bomb-erformationswithstoodnumerousassaultsfromfighters.Withtheadvantage tilting toward the fighters, EighthAir Force had todeviseadditionaltacticstowinairsuperiority. An integrated air defense that employed radar for earlywarning and tracking could inflict losses on the attackers thatcompoundedovertime.Asustainedlossratecomparabletotherateof16percentontheSchweinfurtandRegensburgraidswouldhaverippedthebomberforceinhalfafterfivedays.Intwoweeksofcontinuousoperations,theforcewouldhavebeendrainedtolessthan20percentof itsstartingstrength.Thelossofmachinespalednexttotheloss,injury,andcaptureoftrainedaircrews.Aver-agelossesin1943puttheArmyAirForcesontracktoconsumeitsentireforceatarateoftwo-and-a-halftimesperyear. With radar providing highly controlled intercepts, thebomberformationswerespendingtoomuchtimeinjeopardy,subjecttoorganizedandpersistentattackinsteadofsporadicencounters—conditionsthataircraftdesignersofthemid-1930shad not anticipated. Since the tactics of formation flying didnotcompensateadequately,theadditionalmeasureoffighterescortswithlongerrangemadeupthegap,ensuringthatthebombersspentlesstimeinjeopardyoneachmission. Whatthefightersneededtodotohelpthebomberssur-vivewastoextendtheirrangeandtotaketheoffensive.Lugerdroptanksmetthefirstgoalin1944.Bysweepingaheadofthebomberformations,fightersregainedtheadvantagesofinitia-tiveandposition.JimmyDoolittle,whotookcommandofEighthAirForceinlate1943,laterrelatedthatontakingcommandhespottedasignsayingthemissionofthefighterswastobringthebombersbacksafely.Doolittleordereditchangedtoread:“Thefirst duty of the EighthAir Force fighters is to destroy Germanfighters.”19

Luftwaffe fighter ace and commander Gen. Adolf Gal-landwroteafterthewarthatthedaytheEighthAirForcefight-ers went on the offensive was the day the Germans lost thewar.Theduelbetweenbombers,escorts,andLuftwaffefightersturned inpartonwhodevised thequickest remedies forair-craftsurvivability,andinpartonproductionofaircraft.FortheAllies, escort tactics curtailed losses and destroyed Germanaircraft,bringingattritionratestolevelsthatcouldbemetbywartimeproduction.FortheGermans,thecrucialsurvivability

factorsultimatelycamedowntothelossoftheirtrainedandexperiencedpilots.

Deception Techniques Another clear example of radar’s impact was the Ger-man development of night intercept operations.After the fallof France inMay1940, theRAFhadbegunnightbomberat-tacksonGermanmilitaryandindustrytargets intheRuhrandelsewhere.Germanearlywarning radarcouldstillpickup for-mations on their approach but the problem of visual acquisi-tionandtrackingwasmuchmoredifficulttoperformatnight.However,findinggroundtargetsatnightwasalsomuchmoredifficult. A 1941 report found that only one in five RAF sortiesdroppedbombswithinfivemilesofthetarget.BritishPrimeMin-isterWinstonChurchillorderedhighprioritydevelopmentofra-daraidsfornavigationtoimproveaccuracy.Byearly1942,radarnavigational devices were being installed in heavy bombers.ThehighperformanceH2Ssystemwasavailableonanumberofaircraftbymid-1943,andonJuly24,H2Spathfindersleda740aircraftattackonHamburg. TheGermanscounteredthesefarmoredevastatingnightraidsbyperfectingasystemofground-controllednightfighterinterception thatalsocapitalizedon radar.TheGermannightinterceptoperations linkedradarearlywarningtoasystemofground control and led also to the use of airborne radar forfighterintercepts. Asshowninthefourpanelsofthechartabove,earlywarn-ingfirstcuednightfighterstotakeoffandclimbto20,000feet,wheretheytookupstationonaradiobeacon,awaitinginstruc-tions. When bombers entered the radar range of a groundstation,Germancontrollersvectorednightfighters toan inter-ceptcourse.Onceoncourse,pilots reliedonvisualdetectionandeventhebuffetingofwaketurbulencetofindthebomb-er streams. Night fighter pilots radioed back the position andheadingofthebomberstreams,thenwereclearedtoengage. Duringtheengagement,nightfightersusedspecialmodifi-cationssuchasupward-pointinggunsandshort-rangeairborneradar.Theyalsoemployedairborneradarwitharangeofaboutfourmilestodetectthebomberstream. On the night of March 30, 1944, German night fighters

21


broughtdown107Britishheavybombers intheirraidonNurn-berg.Attheirpeak,Germannightfighterspracticed“themostcomplextypeofmodernaerialcombat,”inthewordsofanof-ficialAmericanAAFaccount.TheairborneradarsofWorldWarIIhadnotyetevolvedtothepointwheretheycouldprovidepre-cisefirecontroltoguideactualweaponstotheirtargets.How-ever,theincreasingexactnessofradar-controlledinterceptwasdeadly enough to spur development of measures to preventradardetection.

Early ECM Radarbegatcountermeasuresalmostimmediately.Asra-dar began to give air defenders a clear picture of the loca-tion,direction,andaltitudeofincomingattackers,theattackerssoughtwaystodenythisinformationtotheenemy.Earlycoun-termeasuresprimarilyaffectedthevariablesofdetectionandengagementinthesurvivabilityequation. Manipulatingtheelectromagneticspectrumthroughcre-ating deceptive returns took three forms: generating clutter,jamming transmissions, and making objects appear larger toconfusecontrollers.Allwerepioneered in some form inWorldWarII. Generating false signals sought to neutralize the earlywarningradarthatformedthebackboneoftheGermannightfighterinterceptsystem.InaFebruary1942commandoraidatBruneval,theBritishseizedaWurzburgradarsetwhichaidedinthedevelopmentofcountermeasures.Theproductwas“Win-dow,” the codename for strips of metallic foil dropped frombomberstosaturateenemyradarscopes. Chaffcomplicated thegroundcontroller’s jobbycreat-

ingnumerous flashesand falseblipsandcloudson the radarscreen. Although countermeasures were developed swiftly, theRAFwaitednearly18monthstousetheminbattle.Seniorplan-ners feared that if the RAF employed countermeasures, theGermanswoulddothesame.20IntheJuly1943Hamburgraids,theRAFused92millionstripsofWindow,whichbroughtGermanradarscopesalivewithfalseechoes.TheRAFlostonly12aircraftratherthanwhatwouldhavestatisticallybeenaround50with-outtheaidofWindow.21

GermanairdefenseswerethrownintodisarraybytheRAFtactics.AccordingtotheLuftwaffe’sGalland:

“Not one radar instrument of our defense had worked. The Brit‑ish employed for the first time the so‑called Laminetta method [Window]. It was as primitive as it was effective. The bomber units and all accompanying aircraft dropped bundles of tin foil in large quantities, of a length and width attuned to our radar wave length. Drifting in the wind, they dropped slowly to the ground, forming a wall which could not be penetrated by the radar rays. Instead of being reflected by the enemy’s aircraft they were now reflected by this sort of fog bank, and the radar screen was simply blocked by their quantity. The air situation was veiled as in a fog. The system of fighter direction based on ra‑dar was out of action. Even the radar sets of our fighters were blinded. The flak could obtain no picture of the air situation. The radar target‑finders were out of action. At one blow the night was again as impregnable as it had been before the radar eye was invented.”22

German counter-counter-measures followed rapidly. Skill-ful operators learned to sort outfalse signals and maintain theabilitytoprovidevectors.TheLuft-waffe engaged 4,000 engineersonprojectssuchastheWurzlauswhich detected the slight differ-encebetweenslow-movingstripsof foilandthebombersflyingat200mph. Other devices tried topinpoint the faint radarmodula-tionpresentonechoes fromair-craft propellers. A set of specialreceiving stationswasequippedto detect transmission from theBritishH2Snavigationradarsets. In the air, German nightfighters switched to three-meterwavelength (90 MHz) radar thatwas unaffected by the Windowstrips that had been cut for 50centimeterradar.23SomeGerman


22

fighters could also detect emissions from the British H2S systemon the pathfinders and a later tail-warning radar. The FuG 227Flensburgradarreceiverwastunedtomatchthefrequencyofthe“Monica”tail-warningradarsetsusedbyRAFbombers.TheFuG350NaxosperformedthesamerolebutwastunedtotheH2Sradarset.TheBritishlearnedoftheseGermandevicesinearly1944whenaJu-88GnightfightermistakenlylandedinEssex. Within10daysoffindingthisaircraft,theBritishdevelopedlonger forms of Window (code-named“Rope”), removed tailwarningradarsetsfrombombers,andorderedbombercrewstouseH2Sonlywhenabsolutelynecessary. AsecondmajorECMdeviceusedinthewar,codenamed“Carpet,” electronically jammed German radar. In October1943,theAlliesfirstusedCarpetasbothabroadband(multiplefrequencies)andspotjammer(singlefrequency).Theideabe-hindjammingwastotransmitsignalsonthesamefrequencyastheradarreceiversothattheoperatorcouldnotsortoutthera-darreturntheysoughtfromsignalssentbythejammingaircraft.TheAlliesusedCarpet,Dina,Rug,Lighthouse,andotherjammersthat were effective in the frequency ranges of most Germanradarsystems.24“Mandrel”jammingaircraftaccompaniedRAFbombers todisruptFreyaradarsets,“Piperack”counteredtheLichtenstein radar, and“Perfectos” triggered German fightersidentificationfriendorfoe(IFF)setstorevealtheirposition. Finally, theBritishexperimentedwithways toblanket thesky with large radar returns that would mimic a large attackforcewherenonewaspresent.“Moonshine”transpondersemit-tedsignalsthatmadeasingledecoyaircraftappearonradarasalargeformationofbombers.Toobtainthenecessaryradioand radar frequencies for these devices, the British sent“fer-ret”aircraftofthesecret192and214RadioCounterMeasuresSquadronalongsidebombingmissionstousesophisticatedre-ceiverstodetectenemytransmissions.25

TwoelectronicarmadaswerepartofthecastfortheNor-mandylandingsonJune6,1944.Asmanyas600radarandjam-ming systems guarded the coastline. Just before the invasion,Allied bombers destroyed key German jamming sites and hitradar installations, leavingasitenearLeHavredamagedbutfunctionalaspartoftheruse.ThentheAlliesprojectedtwofalseinvasionforces,knownasTaxableandGlimmer,byemployingamenagerieofforcestoformlargeradarreflectors. TaxableconsistedofaformationofeightLancasterbomb-ers flying in a pattern dispensing chaff to make the GermansthinkalargeinvasionforcewasheadedtowardCapd’Antifer.TheLancasterswereequippedwith“Moonshine”transpondersthatpickedupGermanradarimpulsesandamplifiedthemtodepictalargerforce.Belowtheaircraft,aflotillaofboatstowednavalbarrageballoonsequippedwithradarreflectorsdesignedtomakethemlooklikelargewarshipsandtrooptransports.TheGlimmerforcemademockrunsagainstDunkirkandBoulogneandusedjammingtoconcealthetruesizeoftheforce.ShipsintheGlimmergroupbroadcastnoisesimulatinganchordrops,and smoke screens concealed operations. Meanwhile, RAF

bombersdroppedhugeamountsofWindowfartothewestoftheinvasionsite.26

Radarcountermeasureshelpedpreservetacticalsurprisefor the invasion force. In theend,onlyoneGerman radar sitepicked up the actual invasion force, and that station’s reportwaslostinthechaosoffalsereportsgeneratedbydetectionsofTaxableandGlimmer.27

The Radar Game and the Theater Campaign Theaircomponentdirectlyaffected the timetableofplanningfortheater leveloperationsthroughoutWorldWarII.Attheoperationallevel,controloftheairwasaprerequi-siteforsuccessfulgroundoperations.InWorldWarIIasneverbefore, the air components set the parameters of theatermilitarystrategyforeachbelligerent.Onehistorianwroteoftheimportanceoftheairoperations intheBattleofBritainand how they were intended to precede a cross-channelinvasion:

“In previous campaigns, the aerial onslaught against the enemy air forces had taken place simultaneously with the army’s advance across the border: for Operation Sealion, it was to be a precondition to military action.”28

SurvivabilityandtheroleoftheaircomponentwasnolessimportantastheAlliestooktheoffensive. Seen in the light of operational planning, survivabilityhadtobeachievedeveninthefaceofaradargamethattookawaytheattacker’selementof surprise.TheRAFandAAFwoncontroloftheskiesoverEurope,albeitatgreatcost.Thepayoff,aslongexpected,wasthefreedomtoconductattackstoshapeandsupporttheNormandylandings.

Survivability and the Theater Campaign: Operation Overlord LandingforcesonthecoastofFrancewasastraightfor-wardbutambitioustask:“Pourmenandequipmentashoreat one or more points so fast that they could overwhelmtheenemydefensesthere,thendiginfirmlytoavoidbeingthrownbackintotheseabythefirstenemycounterattack.”JustastheGermansneededlocalairsuperioritytoattemptSealion, the Allies had to eliminate the Luftwaffe from thebattleareabeforetheinvasion. Thereasonwasfirmlyrootedintheoperationaldoctrinethat had guided plans for the invasion all along. Germanforces in the Normandy region numbered nearly one mil-lion.TheAllieswouldputashorealmost325,000troopswithindaysafterD-Day.However, thenumericalsuperiorityof theGermans had to be offset by denying Field Marshall ErwinRommeltheabilitytoreinforceandmaneuvertodefeattheinvasionforce’stoeholdonthecontinent. Whenaircraftwereassuredofareasonablelevelofsur-vivability,theycouldbecountedontoexecutemissionswith

23


“[I]n an all‑weather Air Force, radar must be the universally used tool for bombing, gunfire, naviga‑tion, landing, and control. … The development and perfection of radar and the techniques for using it effectively are as important as the development of the jet‑propelled plane.”—Theodor von Kármán, August 1945

Developments inguidedmissile technology,combinedwith additional improvements to radar detection, wouldmake the postwar radar game even more deadly. By the1960s,radar’sabilitytoguideeachphaseofthesurvivabilityduelwouldthreatentocurtailtheabilityofaircrafttocontroltheskiesoverthebattlespace. Research on guided missiles had begun during World

directimpactonenemygroundforces.AirsuperioritygaveGen.DwightD.EisenhowertheabilitytoeventhebalanceofgroundforcesintheNormandyregion.Alliedairguardedfriendly forces fromattack,whilegoingon theoffensive toshapethebattlebehindthefrontlines.Airattacksonbridges,roads,andrail transportationpreventedtheGermansfrommovinginreinforcements.Alliedairpowerkepttheroadandrailtransportsystemunderconstantattack.Motortransportmovedonlybynightandeventhenunderbombardment.“Railtransportisimpossiblebecausethetrainsareobservedandattacked in shortorder,” recordedGen. FriedrichDoll-manoftheSeventhArmyHighCommandonJune11,1944.Dollmanwentontoreport:

“Troop movements and all supply traffic by rail to the army sector must be considered as completely cut off. The fact that traffic on the front and in rear areas is under constant attack from Allied air power has led to delays and unavoid‑able losses in vehicles, which in turn have led to a restriction in the mobility of the numerous Panzer units due to the lack of fuel and the unreliability of the ammunition supply.”29

Theeffectsaccumulated,forroadtransportwaslessef-ficientthanrailtransport,androadtransportitselfwasmorecostly because of strategic shortages of rubber tires andpetrol.30

Airinterdictionrestrictedtheenemy’sabilitytoresupply,reinforceandmassforamajorcounterattack,therebyassist-ingtheAlliesastheypressedonwiththeliberationofEurope.The lackofaconcertedchallenge from the Luftwaffeen-abledfreedomofoperationintheskiesoverNormandythat

allowedthetacticalairforcestocontroltheflowofenemyforcesbehindthefrontlines.

In Summary The course of the air war over Europe indicated thatsurvivabilitywasafleetingbalanceofelementsandthatitscomponents could change as different tactics, technolo-gies,andobjectiveswererolledintotheequation.Hadanyof the belligerents introduced their advanced aircraft de-signsinsignificantnumbers,andattherighttime,theymighthavetippedthebalanceoftheairwarbyagainalteringtheequationofaircraftsurvivability.TheMe-262“easilyflewcir-clesaroundourbestfighters,”admittedDoolittle,whoafterthewarremarked,“Ishuddertothinkoftheconsequenceshad the Luftwaffe possessed this aircraft in large numbersandemployeditproperly.” TheradargameofWorldWarIIopenedaneweraofaircombat.Forthefirsttime,aircraftsurvivabilitywasama-jorvariableintheateroperationalplans.Theduelforsurviv-abilitywasnowdominatedbyradarinthedetectionphase.Thesetwochangescameatatimewhencombinedarmsoperationsstartedtodependontheaircomponenttosettheconditions formajorgroundactionand toensure thatattacking forceson thegroundcouldcountonnotbeingstoppedbyenemyair. WorldWarIIalsomarkedcleartrendsthatwouldcon-tinue to alter the duel between attackers and defenders.Experiments with airborne radar in fighters, and with ra-dar-controlledflakandmissiles,indicatedthattheengage-mentphaseandprobabilityofkillwouldsoonbecomepartofradargame,too.

THE POSTWAR RADAR GAMEWarII.TheGermanEnziansurface-to-airmissilewasjustoneofseveralexperiments. Postwarresearch,especiallyintheUnitedStatesandtheSovietUnion,concentratedonguidingmissiles throughon-boardradarorinfraredseekerstoimproveaccuracy.NATOintelligencefirstdiscoveredtheexistenceoftheSovietSA-2in1953.31ThefirstAmericansurface-to-airmissilebecameop-erationalinthesameyear. BoththeUSandtheSovietUnionenvisionedaneedforair defenses to guard their territory from attacking bomb-ers carrying nuclear weapons. An early US missile namedBomarcreliedonaground-controlledradartoturnthemis-sile into attack position. A second radar guidance systemwouldallowtheMach2.7Bomarctolockontoitstargetinflight.32Vast quantities of these radar-guided SAMs with at


24

for“parasite”fighterstobelaunchedfromandrecoveredbybombersthemselveshadproved impractical.Thebomberswould have to approach their targets in the USSR withoutescort.AttackinginnumberswouldalsocomplicatetheSo-vietdefenseproblem.BythetimetheB-52wentintoproduc-tion in 1952, Gen. Curtis LeMay knew that the big bomberwould be conspicuous on radar, but reasoned that its sizewouldeventuallypermitittocarrymoreelectronicgearforradar-jamming.35Besides,SACwasnotnecessarilyposturingfor a sustained offensive. Talk of one-way missions and theknock-out blow of the atomic bomber offensive eclipsedthe calculation of long-term bomber attrition. Still, the factremainedthattheSovietUnionwasdevelopinglongrangeearlywarningradarsandradar-controlledSAMstoengagehostileaircraft. The severity of this threat stood out clearly in a state-mentbyGen.ThomasD.White. Insummer1957, justbeforebecomingUSAFChiefofStaff,Whitestatedthatamixofbal-listicmissilesandbombersinthenuclearfleetwould“permitgreaterversatilityforourforcesbyrelievingmannedbomb-ersofthoseheavilydefendedtargetswherethecostofat-tackingwithbomberswouldbetoohighandwherepreciseaccuracyisnotmandatory.”36Itwasaroundthistime,though,thatspeculationblossomedthatcontinueddevelopmentofradar-guidedmissileswouldusher in“thecomingdeathoftheflyingairforce.37

On the Verge: The U‑2 and SR‑71 Meeting the challenge of integrated radar-controlledairdefensesequippedwithradar-guidedSAMsbecamethechiefpreoccupationofstrategicairwarplannersinthelate1950sand1960s.Aircraftdesignwaspushingthelimitsofhighspeedandhighaltitudeflight,andforatime,thesetwoar-easbecamethenaturalresourcesfornewsurvivabilitytech-niques. Newreconnaissanceaircraftstroveformaximumsurviv-abilitybecausetheirmissionwastooverflytheSovietUnion.Onlyextremecombinationsofperformanceattributescouldkeepaircraftoutof jeopardy.Onetacticwastoflyathigh

leasta25-milerangewouldberequiredtodefendcontinen-talUSairspace.Thegrowingthreatfromradar-controlledmis-sileswasputtingaircraftsurvivabilityintosomedoubt.Radarand infraredseekerscouldguidemissilesmostorallof thewaytothetarget.Radarnowplayedaroleineachstageoftheduel:detection,engagement,andprobabilityofkill. USplannerswerealsowellawarethattheSovietUnionwasbeginningtopresentmoreheavilydefendedtargetstoSAC’sbombers. In1947,discussionsonrequirementsfortheXB-52staredthesedilemmasintheface.Togainmorepay-load,anatomicbomber“mightevenhavetodispensewithguns and armor in order to attain the speed and altitudenecessary to assure its survival.”33 The lack of intelligenceabout threats to be faced over the Soviet Union createdmore complications. An air weapons development boardraisedquestions:

“Would it be possible for them to fly fast enough and high enough to evade the interceptors? Or would they still need to bristle with guns? If the latter were true, development be‑came more complex. Bulky turrets had to be eliminated for aerodynamic reasons, while fire control systems had to cope with high speeds.”

To cap off the dilemma, if enemy fighters had flexibleguns,speedwouldnotyieldadequateprotection.34

The options for countering radar-guided missiles andantiaircraft fire started with traditional improvements, incategories like speed and performance. Mastering jet en-ginesandmakingtheearly jetaircraftsaferandmorereli-ableconsumedtheattentionofaircraftdesigners.Jetfight-erswerejudgedonthesamegeneralperformancecriteriaas were the Spads ofWorldWar I: speed, maneuverability,power,andoverallperformance.Aircraftofthejetagehadgreatly improved performance, but their conventional de-signsremainedjustaseasyforradartospot. Thebombersthatenteredtheforce inthe1950sreliedonaltitude,speed,andatailgunner’sposition.TheB-47,forexample,hadatopspeedofmorethan500knots.Concepts

25


altitude.Builtin1955,theU-2aimedtoflyabovethealtitudeceilingofSovietfighter-interceptors.TheSovietsknewaboutthe U-2 flights from the start. As one of the early pilots re-called:

“I knew from being briefed by the two other guys who flew these missions ahead of me to expect a lot of Soviet air ac‑tivity. Those bastards tracked me from the minute I took off, which was an unpleasant surprise. We thought we would be invisible to their radar at such heights. No dice.”38

Then on May 1, 1960, a barrage of 14 SA-2s broughtdowntheU-2pilotedbyGaryFrancisPowers.ItwasthefirstUSaircraftlosttoaradar-guidedSAM.AnotherU-2wasshotdown in 1962.With the altitude sanctuary pierced, aircraftdesignwouldhavetopresstonewextremestoprevailintheradargame. Tocopewiththeseairdefenses,theSR-71combinedanoperationalceilingof80,000feetormorewithatopspeedof Mach 3+ to enhance survivability on deep penetratingreconnaissancemissions. TheSR-71wasequippedwithECMtojammissileseekers,and itsdesignprobedat thepossibilityofminimizing radarcross section. However, its chief survivability characteristicswerealtitudeandspeed.SAMsfiredat theSR-71oftenex-plodedseveralmilesbehindthestreakingaircraft.“Weknewwe’dprobablygetshotat,butitwasn’tabigworrybecauseatourheightanSA-2missilesimplydidn’thavetheaerody-namic capability to maneuver,” one SR-71 crew memberreasoned.39TheattempttobuildabomberintheleagueoftheSR-71 failedwith theB-70.Lt.Gen.OttoJ.Glasser,chiefofstaffforresearchanddevelopmentin1971,recalled,“TheB-70wascapableonlyofoperatingveryhigh,veryfast,andwhentheSAMmissilescameintooperationaluse,theB-70found it could not operate in its designregimen,andithadlittleresidualcapabil-itytooperateinotherregimes.”40

For aircraft without the SR’sone-of-a-kind performance, survivabil-ity would increasingly rely on means ofdeceiving and thwarting the enemy’sability to detect, track, and engage air-craft.WorldWar II-eraattemptstomountelectroniccountermeasures to radarde-tection had paid off. When Allied ECMjammed German AAA fire control andground-controlled intercept (GCI) radar,visualtargetingofthe88mmairdefenseguns proved much less effective againstbombers flying at 25,000 to 29,000 feet.The addition of ECM was estimated tohave reducedtheAlliedattrition ratebyasmuchas25percent.”41Nowthatradar

controlledeachstageoftheduel,evadingordeceivingfirecontrolradarsandmissileseekersbecameanessentialpartofthesurvivabilityduel.

Operational Challenges: SAMs in Vietnam Five years after the U-2 incident, a North VietnameseSA-2shotdownanAmericanF-4ConJuly24,1965.Theprob-lems of survivability were multiplied for the military aircraftthatoperatedinVietnam.AircraftliketheF-4,F-105,andtheF-111 were designed with features like speed, range, andbomb-carrying capacity in mind. Like their old World WarII-era cousins, the aerodynamic features of these aircraftmadethemlargeradarreflectors.Theircrewsmighttake itforgrantedthatenemyradarwoulddetectthematsomepoint.However,thespeed,maneuverability,andtacticsthatpilots reliedon for survivabilitycouldnotcompletely shieldthemand theirwarplanes from the threatof radar-guidedmissilesclosingatMach2orfaster. By the time the Rolling Thunder operations of 1965-68were in full swing, survivability consisted of multiple duelsbetweenattackingaircraftandthefighters,SAMs,andan-tiaircraft defenses they might encounter. Early warning ra-darcuedfighterinterceptors.SAMbatteriesusedtheirownacquisitionradarstodirectthefirecontrolradar.Antiaircraftgunswithradardirectionfindingoperatedautonomouslytoacquireandshootataircraft. Thedeploymentofradar-guidedSAMbatteriescreatedanewduelbetweenattackersanddefenders.Radarguid-anceforcedthedevelopmentofnewandaggressivetac-tics for survival in theendgame. Forexample, thefirst SA-2missilesreactedslowlyonceinflight.Aircrewsrapidlydevel-opedtactics toevadethemissilebycarryingoutextrememaneuvers that would cause the missile to overshoot andmisstheaircraft.Thechartonp.25diagramsonetacticde-


26

velopedtopitthemaneuverabilityoftheaircraft and the skill of the pilot againstthe missile’s radar guidance and perfor-manceparameters. TheriskofSAMengagementaffectedairoperationsbynarrowingtheoptionsfortactical employment. If aircraft flew in atmedium or high altitude, they would bedetected, tracked, and potentially fireduponby SAMs. If they flew in low, theair-craftwouldgainprotectionfromthenapof the Earth and be able to stay belowtheSAM’sminimumengagementaltitude.Low-altitude attacks, however, plungedaircraft intoaregionofdenseantiaircraftgunfire.Thechartattoprightshowshowmulti-layered defenses increased surviv-abilitythreatsatallnormaloperatingalti-tudes. Here, the survivability duel increasedinintensity,asabarrageofthreatsposedsignificant risks to aircraft at all altitudes.Asoneauthorputit,by1968,the“enemy’suse of the electromagnetic spectrum totrackandshootdownfriendlyaircraftwasa serious problem, and the requirementto neutralize it spurred vigorous activityinboththetraditionaltechnicalECareasand the pragmatic world of fighter tac-tics.”42

Attheheartoftheproblemofcoun-tering SAMs was the system used to de-tect,track,andfireataircraft.Radarassist-edinallphases.InWorldWarII,chaffandcountermeasuresprimarilysoughttoblindthe defenders’ long-range detection fora period of time. By the late 1960s, ECMhadtocounteranddefeatweaponsen-gagementaswellastoshroudattackersfromearlywarningandtracking.Thechartaboveillustrateshowtenuousearlywarn-inglinkstooperationscentersattemptedtohandletargetacquisitionandpassinformationontofirecontrolradarstolaunchSAMs. More integratedairdefensesstrungeachstageofthedueltogether.Successfuldetectionandtrackingledtoen-gagementandenhancedprobabilityofkill.Radarlinkedthestagesof the survivabilityduel together intoan integratedairdefensesystemthathadthepotentialtobemuchmoreeffectiveandlethal. Electronic countermeasures brought back an elementof tactical surpriseandgaveaircrewsabetter survivabilityadvantage by making it more difficult to complete each

stage of radar tracking and engage the aircraft. Electron-iccountermeasuresthrewinabandofclutterthatcuttheeffective range of acquisition and fire control radars. ECMoptimizedfordifferentwavelengthfrequenciesandengage-mentscouldjamawarheadseekerorjamtheradardirect-ingit.Thetacticaleffectwastoreducethetimefortheen-emymissilebatteriestoengage,asdepictedinthetopchartonp.27. Stand-off jamming was not unlike what the British andAmericansaccomplishedinWorldWar II. Itmaskedaircraftfromearlywarningradarstowithinacertaindistanceofthetarget.Morepowerfulsystemsindedicatedaircraftsuchas

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theEB-66raisedthenoiselevelandcouldreducetheeffec-tivetrackingrangeofearlywarningandfirecontrolradar.Bycreatingabeltofjamming,ECMlimitedthetimetheaircraftwasvulnerabletodetectionandtracking,therebyshorten-ingtheenemy’sresponsetime. Successful jamming depended on achieving an ad-equate“jamming-to-signal” ratio.TheJ/S is themeasureofthestrengthofthenormalradarreturnfromanaircraftandthesignalwhichthehostileradarreceivesfromthejammingaircraft.Itvarieswiththesquareofthedistancefromthejam-mer to the receiver being jammed, and thus at great dis-tances,jammingsystemsarelesseffective. Because of its size, the EB-66 could carry larger, morepowerful radar jammers to extend protection to many air-craft.Still,gettingthemosteffectiveresultsfromjammingre-quiredacombinationoftechniques.Inaddition,anaircraftcouldproduceonlya limitedamountofpowerto jamen-emyradarreceivers. New methods of suppressing air defenses focused ondestroyingradarsandSAMbatteriesoutright.Lethalsuppres-sionofenemyairdefenses (SEAD)developedasawaytobreaktheeffectivenessofindividualbatteriesandoftheen-emyairdefensesystemasawhole.WildWeaseltactics,forexample,combinedanextremelysophisticatedradar-seek-ingsensorwithanti-radiationmissilesthathomedinonradaremissions. The various electronic countermeasures (non-lethalSEAD)andlethalSEADtacticsforsuppressingenemyairde-fenses ledplanners toscheduleaveritablearmadaofair-crafttoescortthebomb-droppers.Strikepackagesliketheonedepicted inthechartbelowsoughttocounterall thepotential engagements that the air defense system couldmountagainstalargenumberofaircraftbeingtrackedbyradar.FightersdefendedagainstMiGs.Chaffand jammingmaskedthepackage’sapproachandshielded it toade-greefromSAMs.TheIronHandcomponentssoughtoutnestsofmissile sitesand radar-directedantiaircraftgunsandat-temptedtodestroythem. By combining both lethal and non-lethal SEAD, andfighterescort,thetypicalVietnamstrikepackagelayeredmultiple techniques for survivingdetection, tracking,andattacksbyenemySAMs,AAA,andfighters. AnoperationattheendoftheVietnamWarillustratedhowtheelementsofthestrikepackagesworkedtogethertoenhancesurvivabilityforbombers.“ThestrikepackagewasperhapsthesignificantkeytothesuccessofOpera-tionLinebacker,”concludedanofficialUSAFhistory.43

Linebacker II, the lastmajorairoperationoftheViet-namconflict,wasan11-daybombingcampaignagainsthigh-valuetar

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The Radar Game - Air Force Association · 2010. 9. 30. · On September 12, 1918 at St. Mihiel in France, Col. Wil-liam Mitchell became the first person ever to command a major force