THECOMPLETEHISTORYOFAVIATIONFROMBALLOONINGTOSUPERSONICFLIGHT

TRANSPORTATIONANDSOCIETY

THECOMPLETEHISTORYOFAVIATION

FROMBALLOONINGTOSUPERSONICFLIGHT

EDITEDBYROBERTCURLEY,MANAGER,SCIENCEANDTECHNOLOGY

Publishedin2012byBritannicaEducationalPublishing(atrademarkofEncyclopædiaBritannica,Inc.)inassociationwithRosenEducationalServices,LLC29East21stStreet,NewYork,NY10010.

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FirstEdition

BritannicaEducationalPublishingMichaelI.Levy:ExecutiveEditorJ.E.Luebering:SeniorManagerMarilynL.Barton:SeniorCoordinator,ProductionControlStevenBosco:Director,EditorialTechnologiesLisaS.Braucher:SeniorProducerandDataEditorYvetteCharboneau:SeniorCopyEditorKathyNakamura:Manager,MediaAcquisitionRobertCurley:Manager,ScienceandTechnology

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LibraryofCongressCataloging-in-PublicationData

Thecompletehistoryofaviation:fromballooningtosupersonicflight/editedbyRobertCurley.—1sted.p.cm.—(Transportationandsociety)“InassociationwithBritannicaEducationalPublishing,RosenEducationalServices.”Includesbibliographicalreferencesandindex.ISBN978-1-61530725-8(eBook)1.Aeronautics—Juvenileliterature.I.Curley,Robert,1955–TL547.C5752012629.13009—dc23

2011018093

Onthecover:Ajetfighterplanesoarsabovetheclouds.Jet-enginefighterplaneswereusedsparinglyduringWorldWarII,andwererefinedinthepost-waryears.Shutterstock.com

Onpageviii:HotairballoonstakeflightnearCanterbury,Eng.,aspartofamasscrossingoftheEnglishChannelonApril7,2011.OliScarff/GettyImages

Pages1,18,36,52,82,104,123,145,156,158,161Shutterstock.com

Introduction

Chapter1:BalloonFlightElementsofBalloonFlightThePioneersTheMontgolfierBrothers

TheGas-Hot-AirHybridBalloonSmokeandCoalGasMilitaryExperimentsandPetroleumFuelBalloonsReachtheStratospherePlasticBalloonsSuperpressureBalloonsModernHot-AirBalloons

Chapter2:FlightBalloonsandAirshipsHot-AirBallooningHot-AirBalloonComponentsEnvelopeDesignDeflationSystemsBurnersBaskets

High-AltitudeBallooning

Long-DistanceBallooningSteveFossettCirclestheGlobe

AirshipsTheHindenburgDisaster

Chapter3:TheInventionoftheAirplaneTheProblemofLiftTheProblemofPropulsion

TheWrightBrothersatKittyHawkTheProblemofControlOtherAviationPioneers

Chapter4:PistonsandPropellersTheHeadlinersLindberghCrossestheAtlantic

TheFirstAirlinesFromAirmailtoAirlinesintheUnitedStatesTheDC-3

TheAeronauticalInfrastructureWartimeLegaciesPostwarAirlinesGeneralAviation

Chapter5:TheJetAgeFirstExperimentsWorldWarIITechnicalAdvantagesandChallengesTheBlackBox

TheAirlinesRe-equipProgressinEnginesandAirframes

AirForceOne

Avionics,PassengerSupport,andSafetySupersonicFlightTheConcorde

Chapter6:Helicopters,HangGliders,andUltralightsTheHelicopterHistoryAutogirosPrinciplesofFlightandOperationControlFunctionsTheHangGlider

OttoLilienthalTheUltralight

Chapter7:Airports

ModernAirports

OperationalRequirementsRunwayConfigurationsRunwayPavementsNavigationalAids,Lighting,andMarking

AirTrafficControl

CargoFacilitiesEnvironmentalImpactAirportSecurity

Conclusion

AppendixNotableBalloonFlightsNotableBalloonAltitudeRecordsPioneerAircraftWorld’sBusiestAirportsbyTotalPassengerTraffic(Enplaningand

Deplaning)World’sBusiestAirportsbyTotalMovements(TakeoffsandLandings)

GlossaryBibliographyIndex

INTRODUCTION

Alittlemorethanacenturyago,WilburandOrvilleWrightachievedthefirstpowered,sustained,andcontrolledflightofanairplane,anexperimentthatchangedtheworld.However,theprinciplesofflightwereestablishedwellbeforethen,studiedandtestedbyexplorersandinventorsworldwide.FromtheancientGreekinventorArchimedestotheWrightbrothersandbeyond,humankindhassoughttounlockthesecretsofflight,findingawayforhumanstodefygravityandslipthebondsthatkeepusearthbound.TheHistoryofFlightexaminestheoriginsofthisquest,explainsthemechanismsbywhichflightis

possible,andtellsthestoryofhowaviationhasevolved.Theearliestforaysintohumanflightwereinballoons.Balloonflightis

possiblebecauseofbuoyancy,whichallowsaballoontocarryaweightthatislessthanorequaltothedifferencebetweentheweightoftheballoon(anditsenclosedgas)andthatoftheairthatitdisplaces.Aballoon’sbuoyancycanbecontrolledbychangingtheamountofgasintheenvelope(inthecaseofagasballoon)orbychangingthetemperatureoftheairwithintheenvelope(inthecaseofahot-airballoon),therebychangingitsweightrelativetotheamountofairitdisplaces.Inadditiontoanenvelopeandaheatsource,hot-airballoonsdesignedfortravelhaveabasket,orgondola,forthepassengersandinstruments,andanair-releasesystemforcontrolleddescentandlanding.

TheMontgolfierbrothersoflate18th-centuryFrancewerethefathersofhot-airballooning.Inasmallishballoonoftheirowncreation—withanenvelopeofclothandpaperenclosingairheatedbyburningstraw—theymadethefirstsuccessfulunmannedballoonflightinJuneof1783.InNovemberofthatyear,fellowFrenchmenJean-FrançoisPilâtredeRozierandFrançoisLaurent,marquisd’Arlandesachieveda10-milemannedflightoverParis,witnessedbyFrance’sKingLouisXVIandAmericaninventorandstatesmanBenjaminFranklin.

Overthenexttwocenturies,fuelsourcesforhot-airballoonsmovedfromtheMontgolfiers’originalburningstrawtoincludecoalgas,petroleum,andpropane.Envelopedesignevolvedaswell,movingfromclothandpapertoincludesilkandnylon,and,inthecaseofsuper-pressureballoons,polyester.Propaneburnersandnylonorpolyesterenvelopesremainpopularinhot-airballooningtoday.

Ballooninginthe20thcenturypushedtheboundariesofthecraft.Thedevelopmentofpressurizedsuitsandcabinsallowedforhigh-altitudeflight.High-altitudeballoonshavespecificpracticalapplications,forexample,aerialphotographyandcosmicrayresearch.Modern-dayadventurerspushedthelimitsofballooning,includingSteveFossett,whomadethefirstsoloballoonflightaroundtheworldin2002.Ballooningalsohasbecomeapopularleisureactivity.Commercialhot-airballoonscancarryasmanyas20passengers.

Flightviaairshipsenjoyedabriefpopularityinthefirstdecadesofthe20thcentury.Therearethreetypesofairships.Non-rigidairships,commonlycalled“blimps,”aremadeofmaterialsimilartothatusedfortheenvelopesofgasballoons.Ratherthanabasket,however,anairshipenvelopeisattachedtoacarthathasruddersandasetofpropellersdrivenbyengines.Semi-rigidairshipsalsoaresimilartoblimpsbuthaveametalkeelrunningthelengthofthe

alsoaresimilartoblimpsbuthaveametalkeelrunningthelengthoftheballoon’sbase.

Finally,rigidairshipsaremadeofafabricenvelopesupportedonaframeofmetal.Thistypeofaircraftsawsomesuccessasameansoftransportinthe1920sand’30s.Dirigiblesdesignedby(andnamedafter)FerdinandvonZeppelinwereusedformilitarypurposesduringWorldWarIbybothGermanyandtheAllies.ThefamousHindenburg—thelargestdirigibleeverconstructed—madeaseriesofcross-Atlanticpassengertripsinthe1930s,culminatinginaspectacularcrashonMay6,1937,inNewJersey.Theshipignitedandburneduponlanding,killing36ofits97occupants.

Dirigiblesbecameobsoletenotonlybecauseoftheirlimitationsandsafetyconcerns,butalsoduetotheadvancementsinheavier-than-aircraft,orairplanes.Atthedawnofthe20thcentury,threeobstaclestoairplaneflightremained—lift,propulsion,andcontrol.Thesolutiontothefirstproblem,lift,layinthedesignofwingsfortheaircraft.Theearliestaircraftwingdesignsmimickedtheflappingmotionofbirds.Intheearly1880s,EnglishmanGeorgeCayleydesignedanaircraftwingpatternedaftertheshape,ratherthanthemotion,ofabird’swing,whichledtothecreationofthefirstcambered,orarched,airplanewing.GermanmechanicalengineerOttoLilienthalcompileddataonCayley’sdesign,whichledhimtobuildandsuccessfullyflyanumberofgliders.TheWrightbrothersusedLilienthal’sdataintheirplanedesigns.

Thenextobstaclewaspropulsion.Untilthelate19thcentury,machineswithadequatepowertopropelanaircraftweretooheavy.Bytheendofthecentury,however,internal-combustionengineshadsolvedthisproblem.TheWrightflyerof1903,OrvilleandWilbur’sfirstplane,hadalightweight12-horsepower,four-cylinderenginedesignedbytheWrightbrothers’machinist,CharlesTaylor.

Regardingthematterofcontrol—thelastproblemtobesolved—asuccessfulflightsystemhadtotakeintoaccountfullcontroloverthebalanceandsteeringoftheairplaneinallthreedimensions:roll(thebankingoftheplane),pitch(thedirectionofthenoseupordown),andyaw(thedirectionofthenosetorightorleft).TheWrights’solutionincluded“wing-warping,”orchangingtheangleofthewingstocontroltheplane’sroll,anelevatortocontrolpitch,andaruddertocontrolyaw.In1903,havingsurmountedtheroadblockstoconstructionofacontrollableflyingmachine,theWrightbrothersdebutedtheirplaneatKillDevilHills,nearKittyHawkinNorthCarolina.Theageofairplanetravelhadbegun.

EuropeeagerlyembracedairplaneresearchanddevelopmentintheyearsleadinguptoWorldWarI.Duringthewar,investorsbegantoexplorethe

leadinguptoWorldWarI.Duringthewar,investorsbegantoexplorethenonmilitaryapplicationsofplanesasameansoftravel.Surplusmilitaryplaneswereemployedforpassengertravelandmaildeliveryinthepostwaryears.Competition,bothcommercialandpersonal,ledtolongerflights,acrosscontinentsandoceans,withEuropeanandAmericanaviatorstryingtobestdurationandspeedrecordsthroughthe1920sand’30s.Government-subsidizedairlineswerefoundedinBritainandFrance;operationsintheNetherlands,Germany,andtheSovietUnionweren’tfarbehind.

Meanwhile,intheUnitedStates,decommissionedmilitaryplaneswereatfirstusedprimarilyforairmailservice.TheUnitedStatesencouragedprivatedevelopmentofitsairplaneindustry,andthecompetitionamongprivateentrepreneursultimatelyimprovedthedesignandsafetyofplanes.BoeingandtheDouglasAircraftCompany,withitsDCline,weredominantplayersintheburgeoningU.S.airplaneindustry.

Withthearrivalofpassengerairtravelcametheneedforregulationandsafetystandards.IntheUnitedStates,anumberoforganizationswerecreatedtoinvestigateairplaneaccidentsanddeterminetheircauses.Inthe1920s,aprivateorganizationcalledtheDanielGuggenheimFundforthePromotionofAeronauticsconductedexperimentswithinstrumentationand“blindflight,”supportedadvancesinthemeteorologicalsciences,andestablisheduniversityprogramsinaeronauticalengineering.

WorldWarIItemporarilystalledtheprivateairindustry,asairplaneswereappropriatedformilitaryuse.TheUnitedStatesprovidednearlyalloftheplanesfortheAlliesduringthewar,duemainlytothereliabilityofplanessuchastheDC-3,aswellasthecountry’sabilitytomeetproductionquotas.TheU.S.ArmyAirForceAirTransportCommand(ATC)createdairfields,communicationcentres,andweatherforecastingstationsaroundtheworld.UsingtheATCasamodel,theInternationalCivilAviationOrganization(ICAO)wasfoundedafterthewar,in1947.AnarmoftheUnitedNations,theICAOstandardizedaviationterminology,safetyprocedures,andequipment,andestablishedEnglishastheuniversallanguageforglobalflights.

Airlinesflourishedafterthewar.Flyingbecamethepremieremodeoftravel,withairlinesbookingmorepassengersthanrailwaysandshipsbythe1950s.Duetoanuptickinbusiness,fareswereloweredandflightsbecameanaffordablemeansoftransportationfortheaveragecitizen.Theuseofaircraftforpersonal,business,and“utility”(surveying,cropdusting,etc.)purposesalsoincreased.Together,allmodesofairtransportationnotconnectedtomilitaryorscheduledairlineflightswerereferencedundertheterm“generalaviation.”

Aspistonenginesreachedthelimitsoftheirperformance,airplanedesignersturnedtojetengines,whichweresimplerindesign,longer-lasting,andmoreefficientathighaltitudes.Jetengineshadbeenaroundsincethelate1930’sbutcameintocommonusagebythe1950s.Theswitchtojetenginesnecessitatedchangestothedesignofairplanes.AirlinesrestockedtheirfleetswithjetplanessuchastheAmericanDC-8andtheFrenchCaravelle.Jettechnologyprovedexpensive,sobookingmorepassengerswasrequiredtomakeiteconomicallyfeasiblefortheairlinestomaketheswitch.Otheraviationchangesandimprovementsduringthe“jetage”includedtheadditionofthe“blackbox”datarecordersandsatellitenavigation.

Othermeansofairtravelweredevelopedorrefinedinthe20thcentury,includinghangglidersandultralightairplanes.Therealsowereaircraftthatoperatedusingverticallift.Thegyroplanewasfirstsuccessfullylaunchedin1907bytheBrequetbrothersinFrance.Itonlyrosetwofeetoffofthegroundandwastetheredduetoitslackofcontrol,butitwassuccessfulenoughtoserveassomethingofaprototype.Fromtheretwodistinctmachineswerecreated—theautogiroandthehelicopter.

Usingmotor-drivenhorizontalrotors,helicopterscouldtakeoffvertically,thuseliminatingtheneedforrunways.However,thesemachinesrequiredamoredevelopedstructureandfinelytunedcontrolthanaplane.By1941,thefirstmodernhelicopterhadappeared,completewithathree-blademainrotorforliftandasmallverticaltailrotortocounteracttorque.Thedevelopmentofcontrols—collectivepitch,throttle,antitorque,andcyclic-pitch—allowedforsmoothliftoffs,flights,andlandings.Modernhelicoptersalsofeatureretractablelandinggear,navigationalequipment,andinstrumentssimilartothoseinairplanes.

BeforeWorldWarII,planesonlyneededrunwaysofabout2,000feet—andthosewererarelypaved.Airportswerelocatednearcitycentresandfrequentlynearwateraswell,forseaplanelandings.Today’s100orsolargehubairportsaroundtheworldarevastoperations,withextensivespacededicatedtopavedrunwaysandoperationalfacilities.MorethanhalfoftheselargerairportsarelocatedintheUnitedStates.

Theoperationsofanairporthavetwobasicdivisions—theairsideandthelandside.Airsidefacilitiesincludetherunwaysandplanetaxiareas,airtrafficcontrolandnavigation,emergencyservices,andmaintenance.Landsidefacilitiesincludethepassengerterminal,cargoareas,andaccessroads.Airportsareoftenmanagedbyindependentagencieslicensedbythegovernment,althoughmanyoftheserviceswithinareprovidedbyotheragencies,publicandprivate.Whenselectingasiteforanewairport,locationandtheairport’seffectonsurrounding

selectingasiteforanewairport,locationandtheairport’seffectonsurroundingareasarecarefullyconsidered.Accessibility,noise,andterrainaresomeofthefactorsthatdetermineairportplacement.

Inresponsetoanumberofhijackingsandotherterroristthreatstocommercialaircraftduringthe1960sand’70s,theInternationalCivilAviationOrganizationissuedseveralrecommendationsaimedatairtravel.However,compliancewiththeICAOmeasuresvaried.Essentiallytheonlysolidstandardswerethatpassengerbelongingswerescreened,andthepublicwasdeniedaccesstocertainareas.SincetheattacksofSeptember11,2001,however,airportdesignandoperationhaveundergonemajorchanges.Scrutinyofpassengersandtheirbelongingshasintensified,creatingamassiveexpansionofsecuritypersonnelandequipment,andnecessitatingthatpassengersarrivewellaheadofscheduledflightstoallowenoughtimeforscreening.Additionalattentionhasbeenpaidtolocatingparkingandloadingareasoutsideoftheairport,toreducethedamagecausedbyvehicularexplosions.

Humanlifehasbeenirrevocablyalteredsincetheadventofflight.Beforeairplanetravelwascommon,anindividualwhomovedfarfromhomemightneverhavereturned.Mailsentlongdistancescouldtakeweekstoarrive.Nationsatwarcouldwaitaslongasamonthforsuppliesandtroopstoarrive.Airtravelhasmadeourworldmoreaccessible,andthusmoreinterdependent.TheHistoryofFlightdetailsthefascinatingjourneythathasbroughtthenationsandpeoplesoftheworldclosertogether.

CHAPTER1BALLOONFLIGHT

ThefirstuntetheredmannedballoonascenttookplaceonNov.21,1783,whentwoFrenchmenclimbedintoawickerbasketsuspendedfromthebaseofabeautifullydecorated,paper-linedcottonballoon.Theballoon,filledwithairheatedbyburningstraw,carriedthemenaloftforalittlemorethan20minutesoverParis.WitnessingthisascensionwereLouisXVI,membersoftheFrenchAcademyofSciences,andmultitudesofthepublic,includingtheAmericaninventorandstatesmanBenjaminFranklin.Thiseventleftaprofoundimpressionontheworldofthe18thcentury:Menhadactuallyflown!

Sincethattime,thefieldofflighthasbeentakenoverbyairships,gliders,airplanes,helicopters,andevenrocketsandspacecraft,butballoonscontinuetobeusedforrecreation,competitivesport,andscientificexploration.Hot-airballoonsmaybeusedforshortflightsatlowaltitudesortakenon“longjumps,”usingstrongerwinterwindstotravelhundredsofkilometresataltitudesofuptoabout3km(2miles).Gasballoonscanstayaloftforseveraldaysandtravelathousandkilometresormore.Indeed,combinationhot-airandgasballoonshavecrossedcontinentsandoceansandevencircledtheglobe.Forscientificresearch,specialgasballoonscanfloatinstableconditionsfordaysorevenmonthsatatime,carryinginstrumentpayloadsthroughtheupperreachesofthestratosphere.

ELEMENTSOFBALLOONFLIGHT

Technicallyspeaking,balloonflight(or“lighter-than-airflight”)isthepassage

Technicallyspeaking,balloonflight(or“lighter-than-airflight”)isthepassagethroughtheairofaballoonthatcontainsabuoyantgassuchasheliumorheatedair.ThethreebasicprinciplesofbuoyancywerediscoveredbytheancientGreekmathematicianandinventorArchimedes,the17th-centuryBritishnaturalphilosopherRobertBoyle,andthe18th-centuryFrenchphysicistJacques-Alexandre-CésarCharles:

1.Archimedes’principle(3rdcenturyBCE),whichstatesthatanybodycompletelyorpartiallysubmergedinafluid(gasorliquid)atrestisacteduponbyanupward,orbuoyant,forcethemagnitudeofwhichisequaltotheweightofthefluiddisplacedbythebody;

2.Boyle’slaw(1662),whichstatesthatthepressureofagivenquantityofgasvariesinverselyasitsvolumeatconstanttemperature;and

3.Charles’slaw(1787),whichstatesthatthevolumeoccupiedbyafixedamountofgasisdirectlyproportionaltoitsabsolutetemperature,ifthepressureremainsconstant.

Aballooncancarrythedifferencebetweenitsweight(includingitsenclosedgas)andtheweightoftheairthatitdisplaces.Ninecubicmetres(1,000cubicfeet)ofhydrogenweighsabout2.2kg(5pounds),thesamevolumeofheliumweighsabout4.5kg(10pounds),methane18kg(40pounds),andhotair,atnormalhot-airballoonoperatingtemperatures,22.5kg(50pounds).Thus,theliftingforceofachosengasatlowaltitudescanbeobtainedbysubtractingitsweightfromthetypicalweightofthesamevolumeofair(about34kg,or75pounds,inthisexample).

Becausetheatmosphereiscompressedbyitsownweight,itislessdenseathigheraltitudes.At3,600metres(about12,000feet)theatmosphereisapproximatelytwo-thirdsasdenseandsowillprovidetwo-thirdsthebuoyancy.Thiseffectcontinuesprogressively,sothatat15,000metres(50,000feet)itisonlyone-tenthasdense,at30,000metres(100,000feet)one-hundredth,andat45,000metres(150,000feet)one-thousandth.Inordertocarrythesameloadatanaltitudeof50km(30miles)asatsealevel,aballoonwouldhavetobe1,000timesasbigandyetweighthesame(thatis,keepingeverythingconstantexcepttheballoon’svolume).

Thebuoyancyofahot-airballooniscontrolledbyheatingtheairintheballoonorbychangingtheamountofballast(extraweight).Thebuoyancyofagasballooniscontrolledbychangingtheamountofgasintheballoonortheamountofballast.Tinychangesinoneofthesecomponentscanforcedramaticchangesinaballoon’sflight.Justaone-ortwo-degreechangeintemperaturein

changesinaballoon’sflight.Justaone-ortwo-degreechangeintemperatureinahot-airballoon,afewgramsofballastdropped,oratinyreleaseofgaswillmakeaballoonascendordescendaccordingly.Ontheotherhand,inviolentmaneuvers(suchasduringastorm),wholebagsofsandorgreatblastsofheatfromaballoon’sburnermayberequiredforapropercorrection.Tohelpinrapidatmosphericcooling,modernhot-airballoonsalsohaveverylargehot-airreleaseventsintheformofaparachutethatcansealandunsealanopeninginthetopoftheballoon.

Changingthealtitudeofaballoonwillpermitittofollowdifferentaircurrents.A20-or30-degreedifferenceinwinddirectionusuallyoccursinthefirstfewthousandmetresofaltitude,butafullcircleofwinddirections(“boxwinds”)canalsooccur.Albuquerque,N.M.,isfamousforitsboxwinds,whichcanbeusedtoclimbanddescendbacktotheoriginallaunchsite.Ifthereisonlyasimpleandstablewindpattern,noadditionalcontrolispossible.Withsuperiorweathermonitoring,useoftheglobalpositioningsystem(GPS),andradioorsatellitecommunication,remarkableflightcontrolisnowpossible.Thiselementofcontrol,orthelackofit,isthehallmarkofsportballooning.

TheFédérationAéronautiqueInternationalewasfoundedinFrancein1905.Thisnongovernmentalorganizationmaintainsrecordsformannedflightsfromballoonstospacecraft,aswellasrecordsforflightsofmodelaircraft,unmannedaerialvehicles,andsportingevents.Inaddition,variousnationalaeronauticsorganizations,suchastheBalloonFederationofAmericaandtheBritishBalloonandAirshipClub,maintainballooningrecords.AirworthinessandoperatingcriteriaarecontrolledintheUnitedStatesbytheFederalAviationAdministration(FAA).FAAregulationsforballooningaregenerallyusedbyallcountries,withonlyminorlocalvariations.

THEPIONEERS

Creditfortheinventionofballooninggoestoapairof18th-centurybrothers,Joseph-MichelandJacques-ÉtienneMontgolfierofAnnonay,asmalltownjustsouthofLyon,France.TheItalian-bornEnglishscientistTiberiusCavallohadrecentlydemonstratedthatArchimedes’principleisapplicabletoairborneobjectsbysuccessfullyfloatinghydrogen-filledsoapbubbles.Whenheattemptedtoduplicatethiswithanimalbladders,though,theyprovedtooheavytoascend.Fortunately,theprovincialMontgolfierswerenotconstrainedbylaboratorytechniquesandcreatedtheirhot-airballoononacruderandmuchlargerscale.Becausethearea(andthereforetheweight)ofaballoongoesupby

thesquareofitsdiameterandthevolume(andthereforethelift)increasesbythecubeofitsdiameter,theysucceededhandily.OnJune4,1783,theymadeapublicdemonstrationinAnnonaywitha10.5-metre(35-foot)diameterunmannedcloth-and-paperballoon,usingtheheatfromastrawfire.

THEMONTGOLFIERBROTHERS

Joseph-MichelMontgolfier(1740–1810)andJacques-ÉtienneMontgolfier(1745–99)were2of16childrenofPierreMontgolfier,whoseprosperouspaperfactoriesinthesmalltownofVidalon,nearAnnonay,insouthernFrance,ensuredthefinancialsupportofthetwobrothers’balloonexperiments.In1782theydiscoveredthatheatedair,whencollectedinsidealargelightweightpaperorfabricbag,causedthebagtoriseintotheair.(Accordingtoonestory,possiblyapocryphal,thebrotherstookinspirationfromwatchingJoseph’swife’sskirtsastheybillowedinthekitchenfromtheheatofacharcoalburnerbeingusedtodrylaundry.)TheMontgolfiersmadethefirstpublicdemonstrationofthisdiscoveryonJune4,1783,atthemarketplaceinAnnonay.Theyfilledtheirballoonwithheatedairbyburningstrawandwoolundertheopeningatthebottomofthebag.Theballoonroseintotheairabout1,000metres(3,000feet),remainedtheresome10minutes,andthensettledtothegroundmorethan2km(1.5mile)fromwhereitrose.

TheMontgolfierstraveledtoParisandthentoVersailles,wheretheyrepeatedtheexperimentwithalargerballoononSept.19,1783,sendingasheep,arooster,andaduckaloftaspassengers.Theballoonfloatedforabout8minutesandlandedsafelyabout3km(2miles)fromthelaunchsite.OnNov.21,1783,thefirstmanneduntetheredflighttookplaceinaMontgolfierballoonwithJean-FrançoisPilâtredeRozierandFrançoisLaurent,marquisd’Arlandes,aspassengers.TheballoonsailedoverParis,traveling9km(5.5miles)inabout25minutes.

ThetwobrotherswerehonouredbytheFrenchAcadémiedesSciencesfortheirinvention.Theypublishedbooksonaeronauticsandcontinuedtheirscientificcareers.Josephalsoinventedacalorimeterandthehydraulicram,andÉtiennedevelopedaprocessformanufacturingvellum.Inlateryears,modificationsandimprovementsoftheirbasicdesignforhot-airballoonswereincorporatedintheconstructionoflargerballoonsthatopenedthewaytoexplorationoftheupperatmosphere.ForthisreasontheMontgolfierbrothersareconsideredtobethefirstpioneersof

reasontheMontgolfierbrothersareconsideredtobethefirstpioneersofballoonflight.

WiththenewsfromAnnonay,FrenchinventorJacques-Alexandre-CésarCharles,whoknewthathydrogenwaslighterthanthehot-airsmokeusedbytheMontgolfiers,realizedthatallhehadtodotosucceedwastomakehisballoonexperimentonalargerscale.Thefirstspaceracewason.OnAug.27,1783,Charleslaunchedanunmannedvarnished-silkhydrogenballoonfromParis.ItwasattackedanddestroyedbylocalvillagerswhenitlandednearGonessesome15km(9miles)tothenortheast.TheMontgolfierscounteredbylaunchingahot-airballooncarryingasheep,aduck,andaroosterfromVersaillesonSeptember19todetermineiftheanimalscouldsurviveintheopenairathigheraltitudes.ThefirstpersonatthelandingsiteofthemenagerieballoonwasJean-FrançoisPilâtredeRozier,whowouldbecomethefirstballoonpilot.

FrenchaeronautsJacques-Alexandre-CésarCharlesandMarie-NoëlRobertmadethefirstmannedascentinagasballoon,Dec.1,1783.©Photos.com/Jupiterimages

WhileCharleswasdesigning—andhavingengineeringbrothersMarie-NoëlandAnne-JeanRobertbuild—alargerhydrogenballoonthatcouldcarryhimaloft,deRozierwasteachinghimselftoflyahot-airballoonbyfirstgoingupwitharestrainingrope.BeforeCharlescouldgethisgasballoonready,deRozierandFrançoisLaurent,marquisd’Arlandes,persuadedthekingtopermitthemtomakethefirstmannedfreeflight.OnNovember21theywentaloftoverParis.Alittlemorethan20minutesand16km(10miles)later,theysafelyreturnedtoEarth.TendayslaterCharlesmadethefirstmannedgasballoon

ascension,accompaniedbyMarie-NoëlRobert.OnlandingnearNesles,some36km(22miles)awayfromthelaunchinParis,RobertsteppedouttoletCharlesmakeasecondflight.TheballoonascendedataterrifyingratewithCharlesontheworld’sfirstsolofreeflight.Theballoonfinallyleveledoutatabout3,000metres(10,000feet),andhewasabletobringitdownsafely.

Jean-FrançoisPilâtredeRozierandFrançoisLaurent,marquisd’Arlandes,ascendinginaMontgolfierballoonattheChâteaudelaMuette,Paris,Nov.21,1783.©Photos.com/Jupiterimages

MostofthefeaturesoftheclassicfreeballoonwereincludedinCharles’sfirstmachine.Importantlateradditionsweretherippanel,firstusedonApril27,1839,bytheAmericanaeronautJohnWise,andthedragrope,inventedabout1830bytheEnglishaeronautCharlesGreen.Arippanelisanelongatedsectionoftheballoonthatislightlyfixedinplaceandcanbequicklyrippedorpulledopenatthemomentoflanding.Itaddsgreatlytothesafetyofballooningbymakingquickdeflationpossible.Thedragrope,orcompensator,servestwopurposes.Itisalong,heavyropethattrailstheballooninordertoslowdowntheballoon’sverticalandhorizontalspeedinlandingoperationsbeforethebaskettouchesdown.Ifalandingisaborted,theropeisautomaticallyrecoveredandcanbeusedagain.Inareaswithoutelectricalpowerlines,balloonscan“dragrope”formanykilometresatatimewithouthavingtodropsandorreleasegas.

THEGAS-HOT-AIRHYBRIDBALLOON

Withintwoyearsofhisepoch-makingfirstmannedfreeflight,deRozierbeganthinkingaboutflyingacrosstheEnglishChannel.Tocompensateforthe

shortcomingsofthetwotypesofballoons—hot-airandhydrogen—hecombinedahydrogenenvelopewithasmallhot-airenvelopebelowit.Hydrogenprovidedthebasiclift,whilethehot-airballoonsystemallowedhimtocontrolhisflightwithouthavingtoconstantlydropballastorreleasegas.Hisballoon,christenedTourdeCalais,wasbrilliantlydecoratedwithartworkandmetallicgilding.Accordingtomoderninvestigations,themetalliccoatingcausedastaticdischargethatignitedthevarnishedenvelopesome30minutesafteritslaunchfromBoulogneonJune15,1785.DeRozierandhispassenger,Pierre-JulesRomain,diedwithinminutesoftheensuingcrash,becomingthefirstballoonfatalities.Despitethistragicfailure,deRozier’sinventioneventuallysucceededintheultimatetransglobalballoonvoyagetwocenturieslater.

Thethreebasictypesofballoons(hotair,gas,andagas-hot-airhybrid)were,then,allinventedattheverybeginning.Afourthtype,thesuperpressureballoon,whichiskeptataconstantvolume,wasproposedbyFrenchGen.JeanMeusnieronDec.3,1783,butnotsuccessfullybuiltuntilstrongermaterialsbecameavailableinthe1950s.

SMOKEANDCOALGAS

Smokeballoons,withoutonboardfire,becamepopularforfairsandexhibitionsasparachuteswereperfected.Inparticular,thestandardgrandclimaxofmanycelebrationsattheturnofthe20thcenturywastohaveatrapezeartistascendforhundredsofmetresbelowaballoonbelchingblacksmokebeforejumpingfromthetrapezetoparachutebacktoEarth.

Thesmokewasnotjustfordramaticeffect;itwasessentialtoretainheat,asnofirewascarriedonboard.Cleanaircoolsrapidlyinanascendingballoon,notonlybyradiationbutalsobytheadiabaticprocessofexpansion.Theheatinthecarbonparticlesofsmoke,however,isnotaffectedbythechangeinatmosphericpressureduringanascent,sothesmokeactsasaheatsinkinadditiontofreshlysealingtheporousmuslinfabricthatwastypicallyusedinsuchballoons.

OnJuly19,1821,atthecoronationinLondonofGeorgeIV,CharlesGreenmadethefirstascentinaballooninflatedwithcoalgas.HealsomadeahistoricflightonNov.7,1836,fromLondontoWeilburg,DuchyofNassau(nowinGermany),adistanceofabout800km(500miles).OthergreatflightsoftheperiodincludedFrenchaeronautFrançoisArban’sSeptember1849flightacrosstheAlpsandJohnWise’s1,300-km(800-mile)flightfromSt.Louis,Mo.,toHenderson,N.Y.Wise’sflight,whichwaslaunchedonJuly1,1859,wasatest

oftheaircurrentsforaproposedtransatlanticattempt.

Illustrationshowingtypicalperformancesbyaerialballoonists.PrintsandPhotographsDivision/LibraryofCongress,Washington,D.C.(digital.id.cph3g10308)

MILITARYEXPERIMENTSANDPETROLEUMFUEL

Mannedballoonshavehadonlyminimalmilitaryuse,theSiegeofParis(Sept.19,1870–Jan.28,1871),duringtheFranco-PrussianWarbeinganotableexception.Mail,carrierpigeons,andimportantindividualsweretransportedinballoonsbuiltintheunusedParisrailwaystations,andthepigeonsbroughtmailback.

In1903theRev.JohnM.Baconinventedtheforerunnerofthemodernhot-airballooninEngland.Whilecoalgaswasplentifulandinexpensivelocally,

airballooninEngland.Whilecoalgaswasplentifulandinexpensivelocally,expeditionaryforceshadseverelogisticproblemswithproducinghydrogeninthefieldortransportingheavycompressed-gascylinders.Baconpromotedtheconceptofperformingmilitaryobservationswithahot-airballoonthatwouldburnpetroleum.Histrialsinthesummerof1903weresuccessful,buthedidnotpursueitfurtherandhisworkwentunnoticedintheballooningcommunity.

Duringthe1930s,attemptsweremadetoutilizepetroleumorpropanefuelsbyGermanandAustrianpioneers.Theireffortsweretechnicallypromising,buttheydidnotreplacethesportgasballoon.Thephilosophyofballooningentailedlongflightsatconsiderablealtitude.Hydrogenandcoalgaswereplentiful,inexpensive,andacceptedfearlessly.Heavycottonballoonswiththeircumbersomefuelsystemswerenotsuitedtotraditionalballooningroutines.EveninEngland,wherelong-durationgasflightswerenotpossibleforfearofthesea,therewasnointerest.

FrenchrepublicanpoliticianLéonGambetta(inhat,centre)abouttoescapebesiegedParisforToursbyballoon,October1870,duringtheFranco-PrussianWar.©Photos.com/Jupiterimages

BALLOONSREACHTHESTRATOSPHERE

Unmannedsoundingballoonsforhigh-altitudescientificinvestigationswereintroducedin1893,butmannedballooningwaslimitedtomoderatealtitudesuntilthe1930s.In1931SwissphysicistAugustePiccardinverteda1905conceptiondevisedbyhimandhistwinbrother,JeanPiccard,foradivingship(bathyscaphe).The1931inventionconsistedofasphericalaluminumpressurecabinanda14,000-cubic-metre(500,000-cubic-foot)lightweightrubberized-

cottonnetlesshydrogenballoon.Thiswouldmakepossiblethefirstsuccessfulstratosphereflight.ItcarriedAugusteandhisassistant,PaulKipfer,to15,781metres(51,775feet)onMay27,1931.JeanPiccardandhiswife,Jeannette,wentto17,550metres(57,579feet)onOct.23,1934,withaslightlylargerduplicatethatusedamagnesium-alloycabin.TheofficialprojectwascompletedearlierwhenU.S.NavyLieut.Comdr.ThomasG.W.Settleachievedaworld-recordflightof18,665metres(61,237feet)inthesameballoononNov.20,1933.

JeanandJeannettePiccard’sballoonhadseveralnoveladvances,themostsignificantbeingtheremote-controlpyrotechnicballastingsystem.Contrarytoconventionaldesigns,theyusedblastingcapsandtrinitrotoluene(TNT)tocutcordsoutsidethesealedcapsule.

ThePiccard17,550-metreflightwasfollowedbylong-timeNationalGeographicmagazinecontributorCapt.A.StevensandCapt.OrvilleAnderson,bothoftheU.S.ArmyAirCorps,goingto22,065metres(72,395feet)onNov.11,1935.TheflightwassponsoredbytheNationalGeographicSocietyandtheU.S.ArmyAirCorps.StevensandAndersonuseda100,000-cubic-metre(3,700,000-cubic-foot)rubberized-cottonballooncarryingalargemagnesium-alloycabin.Thatballoon,theExplorerII,wasseventimesthesizeofPiccard’s,butstillwithverysimilarfabric.Thestressintheskinofthegiantballoonwasformidable,resultinginrepeatedfailures.Ononeoccasionthecrew,thistimeincludingMaj.WilliamE.Kepner,barelyescapedbyparachute.

PLASTICBALLOONS

JeanPiccardrealizedthatthegiantsingle-cellballoonhadreachedtheendofitspracticaldevelopment.Largerballoonswouldrequireheavierfabricwithdiminishingreturns.Smalllatexballoonswereroutinelycarryinglightloadstomuchgreaterheights,andPiccardpostulatedthatwithaclusterofthesehecouldextendthelimitsofballooning.ThomasH.JohnsonoftheFranklinInstitutesuggestedusingfewerbutlargercellophaneballoons.Piccard,workingwithJohnson,designedanetlessfilmballoonthatsubstitutedaconicalskinsectionforthesuspensionsystem.Thepayloadwasattacheddirectlytothebaseofthecone.By1937PiccardandhisstudentsattheUniversityofMinnesota,includingRobertGilruth(laterheadofProjectMercury),hadflownoneoftheseunmannedballoonsabout1,000km(600miles),carryinganautomaticballast-releasingdeviceandradioinstrumentation.

Piccarddreamedofastratosphereflightwithaclusteroffilmballoons,but

therewasconcernthattheywouldbecometangled.Totesttheconcept,hemadeasuccessfulsoloflightinthePleiadeswithanensembleof92latexballoonsonJuly18,1937.

AfterWorldWarII,GeneralMills,Inc.,acceptedacontractfromtheU.S.OfficeofNavalResearchtoadvancethetheoryofballooning.TheDuPontCompany’snewpolyethylenefilmwaschosenfortheenvelope.Launchesofindividualtestballoonswerefinallysuccessful,buttherewaslittlefaiththatthecomplicatedtaskofrigging80oftheseatoncewouldwork,andtheprojectwasabandoned.However,theplasticballoonhadbeencreated,andtheyconstantlygrewlargerandmoreacceptableaspolyethylenefilmsimproved.

Theconversionoftheseamtapes—fromtheiroriginalsimplejoiningtasktobackupuseoverheat-weldedseamsand,finally,withreinforcingfilaments,totheprimarystructuralload-bearingfactor—enabledfurthersizeincreasesandadvancedreliability.Theirusealsoenabledtheabandonmentoftheloadringinthemouthoftheballoon.Thisfacilitatedthedevelopmentofthenaturalshape.

InDecember1955theU.S.AirForceestablishedProjectManHightoobtainscientificdataonthestratosphereandtotestequipmentforexploringaboveEarth’satmosphere.Threepilots,Capt.JosephW.Kittinger,Maj.DavidSimmons,andLieut.CliftonM.McClure,inManhighI(June2,1957),ManhighII(Aug.19,1957),andManhighIII(Oct.8,1958),respectively,eachascendedtoabout30km(19miles)aboardasingle-cellplasticballoon.Unmannedflights,generallycarryingscientificresearchpayloadsofmorethan2,250kg(5,000pounds),havereachedaltitudesabove42km(26miles)withballoonsasbigas1,000,000cubicmetres(some40,000,000cubicfeet).

SUPERPRESSUREBALLOONS

Polyesterfilmatatensilestrengthof1,400kgpersquarecm(20,000poundspersquareinch)—comparedwithpolyethyleneatatensilestrengthofabout40kgpersquarecm(600poundspersquareinch)—finallymadeitpossibletoproducesuperpressureballoons,whichdonotexpandorcontractastheenclosedgasheatsuporcoolsdown.

AseriesofcontractswereawardedtotheG.T.SchjeldahlCompanybytheU.S.AirForceinthelate1950stodeveloppolyesterballoons.Afterrepeatedfailures,DonaldPiccard(sonofJeanandJeannettePiccard)wasassignedtheproject.Hetheorizedthatthefailureswerecausedbytheself-destructivetendenciesofthestifffilm.BylaminatingtwolayersofverythinMylar,he

producedamoreflexiblefilmthatresultedinthefirstsuccessfulsuperpressureballoon.TheseballoonshavebeenusedbytheU.S.NationalCenterforAtmosphericResearchtocarryinstrumentationaloftformonthsatatime,continuallycircumnavigatingEarth.

AweatherballoonisreleasedataweatherstationattheSouthPole.NOAA

Mannedsuperpressureballoonshavehadsomesuccessbuthavenotyetbeenabletocarryonthroughdiurnalheatingcycles.

MODERNHOT-AIRBALLOONS

AsmallgroupofengineersunderWesBorgesonatGeneralMillsdevelopedapolyethylenehot-airballoonwithapropaneburnerthatwassuccessfullyflownbyTomOlsonandlaterbyPaul(“Ed”)Yostperhapsasearlyas1955.Yost,thenatRavenIndustries,madethefirstpublicizedflightofthemodernhot-airballoonin1961atBruning,Neb.Theballoon,developedfor“silententry”(military)use,wassoonfoundtobeunsuitedforcovertoperationsbecauseofthenoiseandlightfromtheburners,andtheclassifiedprojectwasapparentlyabandoned.Althoughtheseballoonsprovedunsuitableformilitaryuse,MarkSemichandDonaldPiccardpursuedtheirAmericanmanufactureforsportservice.

Yost’shot-airballoon,usingstronganddurablenylonfabricinsteadofgossamerpolyethylene,didnotuseloadtapes.Whileloadtapeshadbeenanimportantfactorinthesuccessoffilmballoons,theywereconsideredunnecessaryforfabricballoons.However,withthegrowthofsportballooning,alongerlifeandasaferdesignwererequired.In1964DonaldPiccardadoptedthe

longerlifeandasaferdesignwererequired.In1964DonaldPiccardadoptedthefull-lengthloadtapesfoundonplasticballoonsforfabricballoons.Coincidentally,thisaffordedtheopportunityforhisinventionofthebulbousgore,orpumpkin-shapedballoon.

AmericanaeronautTracyBarnesadaptedaventingsystemusedinparachutestomakethemostimportantadvanceinsafetyandcontrolofhot-airballoonssincetherippanel.Barnes’sparachutetophasalsobeenusedingasballoons.Hisnovelthree-cornerbasketandthree-pointsuspensiondistinguishhisballoonsfromthecommonplace.

CHAPTER2FLIGHTBALLOONSANDAIRSHIPS

Lighter-than-airflightisperformedmostoftenbyhot-airballoons,whichusegasburnerstoheattheairenclosedinafabricenvelope.Inaddition,gasballoonsareusedforhigh-altitudeballooning,usuallyforscientificresearchpurposes,andlong-distanceflightshavebeenachievedbyhot-airballoons,gasballoons,andcombinationhot-airandgasballoons.Airshipsareatypeoflighter-than-aircraftthatenjoyedabriefascendancyintheearly20thcenturyandareseentodayinonlysmallnumbers.

HOT-AIRBALLOONING

Hot-airballoonsarecommonlyusedforrecreationalpurposes.Inadditiontoquietmorningorafternoonflightsdriftingcross-countrytoenjoytheview,manyballoonistsenjoycompetitivesportingeventsandattemptingtosetnewrecords.Aballoonistmayflyaloneinthebasketorcarryseveralpassengers.Oftenseveralballoonsmeettolaunchtogetherwithoutanycompetitivegoals.Individualflightsgenerallylastfromonetothreehoursandmaygoseveralkilometres,thoughtheyoftenlandveryclosetothetakeoffpoint.

Balloonralliesmayconsistofjustafewballoonsforaone-dayoutingoruptoseveralhundredballoonsforaweeklongfestival.Competitiveeventsincludedistancewithinatimelimit,spotlanding,and“hareandhound”races.Hareandhoundracesareeasytoorganizeandjudgesincetheyrequireonlyone(hare)

balloontolaunchfirstandflyareasonabledistance.Thecompetitorsattempttolandascloseaspossibletothehare’slandingposition.Incrowdedconditions,markersareoftendroppedtosimulatethelandings,andtheballoonsflyontomoreopenlocations.

Commercialrideoperatorsareinbusinessalmosteverywhereintheworld.Somerideballoonscarry10to20passengersatatimeingiganticpartitionedbaskets.InCaliforniaandFrance,wine-countryflightsarepopulartouristattractions.Africansafariflights,atlowaltitudeovervastgamepreserves,areperhapsthepinnacleofrideballooning.

HOT-AIRBALLOONCOMPONENTS

Hot-airballoonsconsistoftheballoonenvelope,whichcontainstheheatedairthatgivesthecraftitsbuoyancy;thesystemofburnersthatheatstheaircontainedbytheenvelope;andsomesortofbasketorgondolatocarrypilots,passengers,andsupplies.

ENVELOPEDESIGN

Hot-airballoonsvaryconsiderablyindesignandmaterials.Lightweightcoatednylonandpolyesterfabricsarethemostcommonmaterialsforenvelopes.Cottonisveryserviceablebuthasacomparativelypoorweight-to-strengthratioandisonlyfavouredforcarnival“smoke”balloons.Speciallyshapedballoons,whichareliterallypneumaticsculptures,arepopularatpublicevents.Theyutilizespecialtailoringandmanyinternalbafflesandcordstoattainthedesireddesigns.

Basiccomponentsofahot-airballoon.EncyclopædiaBritannica,Inc.

Sportballoonstypicallyhaveasilhouettesimilartothenaturalshapeoffullyinflatedgasballoons.Theycanbeassembledwithmanyverticalgores(fabricsections,orpanels)orfewerhorizontalgores.Thegorematerialcanbecutstraight(withthefabric’snaturalgrain)oronthebias(diagonaltothefabric’snaturalgrain).Ifstraightgoresareused,excessmaterialcanbegatheredtocreateaflutedpatternthatprovidessomeflexibility.Goresmadeofbias-cutmaterialshavegreaterstretch,whichprovidesanaturalflexibility.Withhorizontalgores,theindividualpanelscanbegatheredtoprovideabulbousgore,whichgivesevengreaterflexibility.Becauseofthegreatlyreduced

effectiveradiusofcurvature,abulbousgoreballoonexperiencesmuchlessstressontheenvelopefabric.

Withbiasgores,loadtapesknownastensorsaregenerallysewnlooselyintoductsformedintheverticalseams,muchliketheshroudlinessewnintoaparachute’sradialseams.Withotherballoons,theloadiscarriedintapessewnorheat-sealeddirectlytotheverticalseams.Oneloadtapecanandshouldhavemorethanenoughstrengthtocarrythewholeloadwithoutanexcessiveweightpenalty.Thestressintheskinoftheballoonissolowthatnormalhandlingwillcausevisibledamageifthefabricisweakenedbywearorexposurelongbeforeitwouldfailinnormalflight.Theimportanceofloadtapesandadequateexcessstrengthintheminballoonconstructioncannotbeoveremphasized.Catastrophicfailureinaproperlydesignedballoonisextremelyrare.

DEFLATIONSYSTEMS

Landingabagwithsomefourtonsofairinitat30km(20miles)perhourwithoutwheels,steeringgear,orbrakespresentssomeproblems.PriortoJohnWise’sdiscoveryoftherippaneldeflationsysteminthemid-19thcentury,agasballooncouldbedraggedalongforseveralkilometresbeforecomingtoastop.Inparticular,balloonsonextendedflightsseemedtobedrawnintolowpressuresystems,whichoftenresultedinstormylandings.

Thebasichot-airballoonrippanelisasimplelargesleeveattheapexthatisdrawnintoabunchandtiedoffwithacord.Thecordistypicallycutremotelybyanelectricallyactuatedexplosivesquibcannonorreleasedwithapullcordmomentsbeforetouchdowninordertodeflatetheenveloperapidly.Thisconfigurationisknownasapoptop.Otherballoonmodelsuseacircularpanelheldinplacewithahook-and-loop(e.g.,Velcro)closurethatcanbeopenedandclosedprogressivelyforfineradjustmentsinbuoyancy.ThatsystemismoreoftenreplacedwithTracyBarnes’s“parachutetop,”whichisacombinationventinganddeflationpanel.Theparachutetopconsistsofasimpleholeattheapexoftheballoon,usuallyaboutone-quarteroftheballoon’sdiameter,pluggedwithaparachuteofslightlygreaterdiameter.Theparachuteispositionedbycordsradiatingoutafewmetresfromtheparachute’sedgetoanchorslocatedonthepuffygorecentres.Aventingcordleadsfromthejunctureoftheparachute’sshroudlinestothebasket.Sometimesamechanicaladvantageisgainedbyapulleysystem.Pullingthecorddrawstheparachutedownintotheballoon,therebylettinghotairescape.Releasingthecordsnapstheparachutebackintotheclosedpositionwiththeforceofthehotair.Iftheparachuteispulledfar

enoughintotheballoon,itwillcollapse,lettingtheballooncompletelydeflaterapidly.Thisisagreatadvantageinhigh-windlandings,whereitmightbedifficulttomaintaintensiononthecord.Someversionsuseseparateretractingcordstoforcetheopeningtoclose,redundantcinchcordstobunchtheparachuteforhands-offdeflation,andelasticcentringcordstoprovideautomaticrapidsettingandresettingoftheparachute.

BURNERS

Earlyhot-airballoonsburnedstrawandalcoholspiritsforfuel,thoughby1900thesefuelshadbeenreplacedwithpetroleum.Compressedliquefiedpropaneisusedalmostexclusivelytoday.Hot-airballoonburnersusevaporizingcoilstopreheatthefuelforefficientcombustion.Mostofthesecoilsaremadeofstainlesssteel,butcoppercoilsalsoworkadequately.Theburnersaremounted,oftenongimbals,onthesuspensionconcentrationringbetweenthebasketandthemouthoftheballoon.Asecondarysystemwithoutvaporizationandslowerairmixingcanprovidemuchquieteroperationandgiveredundancyforsafety.Manydesignsusemultipleduplicateburnersandfuelsuppliesbecausetherehasbeenahistoryofleakingsealsoncontrolvalvesandoccasionallycontaminatedfuel.

BASKETS

Passengerbaskets,orgondolas,varyasmuchindesignasenvelopes.Foreasytransportation,collapsibletubularframeswithstoutfabriccoverscanmeetminimumrequirements.Originally,wickerbasketshadmanilaropewovenintothebasketforsuspension,butbecauseofthepotentialforrot,thesewerereplacedwithsyntheticorsteelcables.Heavywickerworkframes,usingrattanuptoafewcentimetresindiameter,typicallyhavealsobeenreplacedwithmetalorplasticframing.

Wickerconstructionhasanadvantageovermetalskeletonsandhardfibreglassshellsinitsabsorptionofthekineticenergyofimpacts,however.Wickerisalsofavouredforitsnostalgicartisticappearance.Anybasketcanhaveclosed-cellfoampaddingontheinsideforpassengersafetyandcomfort.

Metalliccomponentspresenthazardsintheeventofcontactwithelectricalpowerlines.However,wickerworkbyitselfprovideslittleprotectiontothepassengersorfueltanksfromsuchcontact.Vacuum-formedmonocoqueplasticbasketsareslowlycomingintouse.Theyprovideadvancedimpactandelectricalcontactresistance.

contactresistance.

HIGH-ALTITUDEBALLOONING

Sincethe18thcentury,ballooninghascontinuallyachievedhigheraltitudes.FromCharles’s3,000-metre(10,000-foot)ascentin1783toU.S.ArmyAirCorpsCapt.HawthorneC.Gray’sfatalascentto12,950metres(42,470feet)in1927,themaximumaltitudewasonlylimitedbythepilot’sneedforoxygen.Lackingconfidenceintheabilitytosealanaircrafthermetically,AmericanaviationpioneerWileyPostandothersconcentratedonindividualpressuresuits.Evenaslateas1937,prominentaeronauticalengineerspubliclyderidedtheconceptofbuildingairplanepressurecabins.

ThePiccardinventionofthestratosphereballoonopenedupnewheightsforexploration.Thefirststratosphereflightsweremountedtostudycosmicrays,whichareabsorbedastheyenterEarth’satmosphere.Earlyhigh-altitudeworkwithplasticballoonscontinuedcosmicrayresearch,airsamplingfordetectingatomicexplosions,photographicflightsoverforeignterrain,astronomicalobservationsabovethedisturbancesofthetroposphere,andevenaerodynamictestingoffree-fallingpayloads.Aballoonistheonlystableplatformforanytypeofobservationabovetherangeofairplanesandbelowtherangeoforbitalspacecraft.Itisalsotheonlyaircraftthatdoesnotaffectitsenvironmentandtheonlydevicethatcansitrelativelymotionlessaboveheightsobtainablebyhelicopters.

Balloonsforhigh-altituderesearcharegenerallymadeofpolyethyleneorpolyesterfilm.Someofthesepolyethylenefilmsarelessthanatenthofamillimetrethick.Inordertocarryapayload,theseamsarereinforcedwithload-bearingtape.Whenascientificpayloadisattachedtothebottompointofamodernballoon,theenvelope,ifgivenoverallexcessmaterialcircumferentially,willformtheshapeofanacornsquash.Thisisaresultofthenaturalstressesonthe“skin”causedbythetensionfromthepayloadandthevaryinginternalforcesofthegas,whichdependontheelevationinsidetheballoon.Additionalexcessmaterialinthehorizontaldimensionwillonlyresultinloosewrinkles.Lesshorizontalfullnesswillcausetightspotsorevenindentations.Alargelightlyloadedballoonwillbevery“fat.”Thetopwillhavealargeflatorevenindentedarea,andthebottompointwillhaveanobtuseincludedangle.Iftheballoonenvelopeisonlyasmallpercentageofthetotalweight,theballoonwillhavemoreofaninvertedteardropshape,andthebottompointwillhaveanacuteincludedangle.Thisfamilyofcrosssectionsisknownasthe“naturalshape.”

High-altitudeplasticballoonsareonlypartiallyinflatedatlaunchtoallow

High-altitudeplasticballoonsareonlypartiallyinflatedatlaunchtoallowforgasexpansionastheballoonclimbs.Thisexpansionisroughlytenfoldforeach15,000metres(50,000feet)ofaltitude.Inflightthepayloadisgenerallysuspendedfromanopenextendedparachuteconnectedatitsapextothebaseoftheballoon.Theparachutecanbereleasedbyradiocontrol.Atthemomentofrelease,theelasticityoftheparachutesnapsitopenalmostinstantly.Aradio-controlledgasvalvecanbeusedatthetopoftheballoon.Excessgasisventedbyductshighonthesideoftheballoon,withtheiropeningsatthebaselevel.Iftheductisplacedhighenoughontheballoon,itisimpossibleforoutsideairtoentertheballoon.

Contaminationoftheliftinggasbyoutsideairwilllowerthepossibleceilingoftheballoonand,inthecaseofhydrogen,createafirehazard.Thedesignmustassurethatflowresistanceintheductdoesnotcreateadversebackpressure,whichwouldbursttheballoon.Thediameteroftheduct,itslength,andanypossiblekinksmustbeconsidered.Theweightoftheductitselfcanpullitdownenoughtoblocktheopeningintotheballooninsomecases.Withtheductdesign,anyentrainedairfrommishandlingduringinflationorminuteleaksintheballoonbelowthebaseoftheliftinggaswillpoolinthebaseoftheballoonandlowertheceilingaccordingly.

Ahigh-altituderesearchballoonpreparingfortakeoffatNASA’sGoddardSpaceFlightCenterinMaryland.Theinvertedteardropshapeoftheballoonindicatesthattheenvelopeaccountsforasmallpercentageofthetotalweightofthecraft.SSPLviaGettyImages

Thenaturalshapegivesaballoonverylowskinstressunderstaticconditions.Ataltitudetheballoonisverystableandnotgenerallysubjecttoturbulenceordynamicloads.Onthewayup,theballoonisonlypartiallyinflatedandhasgreatflexibilitytodistort,relievinganystress.

Thefirstmannedstratosphereballoonusedasphericalaluminumcabin.Followingonesusedmagnesiumalloysandspunaluminum.Currenthigh-altitudepressurecabinsaremadewithvariouscompositematerials.Internalpressureismaintainedbyonboardliquidoxygensuppliesandairscrubberstoremovecarbondioxide,moisture,andotherbodyproducts.

Severalflightshavebeenmadewithnocabinatall.Crewsinopengondolas

Severalflightshavebeenmadewithnocabinatall.Crewsinopengondolaswearspacesuitssimilartothosethatastronautswear.

LONG-DISTANCEBALLOONING

Flyingforevergreaterdistanceshasalwaysbeenagoalofballoonists.ThefirstsuccessfulaerialcrossingoftheEnglishChanneloccurredonJan.7,1785,inagasballoonpilotedbyFrenchballoonistJean-PierreBlanchardandAmericanballoonistJohnJeffries.Anotherearlylong-distanceflightwasbytheEnglishballoonistCharlesGreen,accompaniedbytheIrishmusicianThomas(“Monck”)Mason,aboardtheGreatBalloonofNassauinNovember1836.TakingofffromLondon,theytraveledabout750km(480miles)in18hourstolandintheDuchyofNassau(nowinGermany).Paul(“Ed”)YostandDonaldPiccardmadethefirsthot-airballooncrossingoftheEnglishChannelin1963.

TheNewYorkSunnewspaperreportedonApril13,1844,thatMonckMasonhadmadethefirsttransatlanticballooncrossing,butthereportturnedouttobeahoaxperpetratedbyEdgarAllanPoe.Theactualfirsttransatlanticballooncrossingoccurredin1978aboardtheDoubleEagleII,ahelium-filledballoonbuiltbyYost,withpilotingdutiessharedbythreeNewMexicobusinessmen,BenL.Abruzzo,MaxieAnderson,andLarryM.Newman.Thefirsttranspacificballoonflightwasmadein1981byAmericansAbruzzo,Newman,RonClark,andRockyAokiaboardthehelium-filledDoubleEagleV.

In1987BritishentrepreneurRichardBransonandSwedishaeronautPerLindstrand,aboardtheVirginAtlanticFlyer,madethefirsttransatlanticflightinahot-airballoon.Andin1991,aboardtheOtsukaFlyer,theymadethefirsttranspacificflightinahot-airballoon.In1984AmericanaviatorJosephW.Kittinger,aboardthehelium-filledRosieO’Grady’sBalloonofPeace,madethefirstsolotransatlanticballoonflight.In1995AmericanadventurerSteveFossett,aboardthehelium-filledSoloChallenger,madethefirstsolotranspacificballoonflight.

Severalaround-the-worldballoonflightswereattemptedwithvarioussystems,butsuccesswasfinallyachievedin1999bySwissballoonistBertrandPiccard(sonofJacquesPiccard,grandsonofAugustePiccard,andsecondcousinofDonaldPiccard)andBritishballoonistBrianJonesaboardacombinationhot-airandheliumballoon,theBreitlingOrbiterIII,withapressurizedcabin.Thefirstsoloaround-the-worldballoonflightwasmadebyFossettaboardacombinationheliumandhot-airballoon,theBudLightSpiritofFreedom,in2002.

ThesuccessoftheBreitlingandSpiritofFreedomdependedonseveralindependentfactors.Balloondesign,cabindesign,andmeteorologicaltechniquewerealluniqueandindividuallycritical.Whileitmaybepossibletouseothertechniques,allmannedmajorlong-distanceeffortshaveutilizedthejetstream.Thislimitsthealtitude,track,andseasonforasuccessfulattempttothewintermonthsinmid-latitudesatelevationsofabout6,000to10,000metres(about20,000to35,000feet).

RichardBranson(left,front)sittinginthecabinoftheVirginAtlanticFlyerpriortomakingthefirsttransatlanticflightinahot-airballoon.HultonArchive/GettyImages

Inordertonavigateaballoononalong-distanceflight,thepilotmusttakeadvantageofmeteorologicalconditions.Sensitiveattentiontoaltitude,rateofclimb,andglobalpositioninginstrumentationisessentialinordertofollowminute-by-minuteadvicefromground-basedweathercoaches.Information,includingcompleteweathermaps,canbecommunicatedbywirelessInternete-mailconnections.Foranintercontinentalflight,whichmaytakeseveraldays,reevaluationofcomputer-generatedweatherpredictionsisimportant;forglobalcircumnavigationitisessential.

Forasuccessfulglobalvoyageonlyageneralmeteorologicalconditioncanbechosen.Itisimpossibletocalculateweatherconditionstwoandthreeweeksinadvanceatlocationsaroundtheworld.Thegeneralconditionandtheimmediateforecastgovernthedecisiontolaunch.Oncetheballoonisairborneandonitsway,theweathermodelmustbeconstantlyupdatedandtheballoonnavigatedpreciselytotakeadvantageofvaryingconditions.Whiletheaeronautsofthe19thcenturyhadballoonsthatcouldtheoreticallycrosstheAtlantic,allattemptsfailedbecausetheylackedthemeteorologytomakeaccuratepredictionsandthemeanstocommunicatepredictionstotheballoonist.

predictionsandthemeanstocommunicatepredictionstotheballoonist.

STEVEFOSSETTCIRCLESTHEGLOBE

JamesStephenFossettwasbornonApril22,1944,inJackson,Tenn.HegrewupinCalifornia,wherehestudiedeconomicsandphilosophyatStanfordUniversity(B.A.,1966).AfterearninganM.B.A.(1968)atWashingtonUniversityinSt.Louis,Mo.,hebecameasuccessfulcommoditiesbroker,andin1980hefoundedthesecuritiescompanyLakotaTrading.

Fossettundertookanumberofchallenges,includingswimmingtheEnglishChannel(1985),beforegaininginternationalattentionwithhisballooningfeats.In1995heregisteredhisfirstrecordinthesportwithasolotranspacificflight.Thefollowingyearhebeganhishighlypublicizedefforttobecomethefirstpersontoballoonaroundtheworldalone.Theinitialattempt,however,endedafterthreedays,andaseriesofsubsequenteffortsalsofailed.In2002Fossettmadehissixthattemptattherecord,takingofffromNortham,WestAustralia,intheBudLightSpiritofFreedom.OnJuly2hemadehistoryashecrossedhisstartingpoint,eventuallylandingintheoutbackofQueensland.

In2005Fossettbecamethefirstpersontoflyanairplanearoundtheworldsolowithoutstoppingorrefueling.PilotingtheGlobalFlyer,aspecializedplanethatfeatured13fueltanksanda2-metre(7-foot)cockpit,hetookofffromSalinas,Kansas,onFebruary28andreturnedtheresome67hourslater,onMarch3.OnFeb.8,2006,heundertookthelongestnonstopairplaneflight,takingofffromCapeCanaveral,Florida,aboardtheGlobalFlyer.Some76hourslater,onFebruary11,hemadeanemergencylandinginBournemouth,England,havingcoveredarecord42,469.5km(26,389.3miles).

Fossettwasalsorenownedasaspeedsailor.In2001herecordedthequickesttransatlanticcrossing—4days17hours28minutes6seconds—andin2004hecircumnavigatedtheglobeinanunprecedentedtimeof58days9hours32minutes45seconds.Bytheearly21stcentury,hehadsetsome100recordsinsailingandaviation.Hisotherachievementsincludedthefastestflight(1,194.17km,or742.02miles,perhour)inanonsupersonicairplane(2001)aswellasanumberofglidingrecords.

OnSept.3,2007,Fossettwasreportedmissingafterhissingle-engine

planedisappearedduringascoutingmissioninwesternNevada.Subsequentsearcheffortswerehamperedbythearea’sremotenessandruggedterrain.OnFeb.15,2008,FossettwasdeclareddeadbyacourtinChicago.InOctoberthewreckageofhisplaneandhisremainswerefoundinInyoNationalForest,Nevada.

AIRSHIPS

Airshipsareself-propelled,lighter-than-aircraftthatarealsocalleddirigibles,fromtheFrenchdiriger,“tosteer.”Threemaintypesofairshipshavebeenbuilt:nonrigids(blimps),semirigids,andrigids.Allthreetypeshavefourprincipalparts:acigar-shapedbag,orballoon,thatisfilledwithalighter-than-airgas;acarorgondolathatisslungbeneaththeballoonandholdsthecrewandpassengers;enginesthatdrivepropellers;andhorizontalandverticalrudderstosteerthecraft.Nonrigidsaresimplyballoonswithcarsattachedbycables;ifthegasescapes,theballooncollapses.Semirigidslikewisedependontheinternalgastomaintaintheballoon’sshape,buttheyalsohaveastructuralmetalkeelthatextendslongitudinallyalongtheballoon’sbaseandsupportsthecar.Rigidsconsistofalightframeworkofaluminum-alloygirdersthatiscoveredwithfabricbutisnotairtight.Insidethisframeworkareanumberofgas-filledballoons,eachofwhichcanbefilledoremptiedseparately;rigidskeeptheirshapewhethertheyarefilledwithgasornot.

Theusualgasesusedforliftingairshipsarehydrogenandhelium.Hydrogenisthelightestknowngasandthushasgreatliftingcapacity,butitisalsohighlyflammableandhascausedmanyfatalairshipdisasters.Heliumisnotasbuoyantbutisfarsaferthanhydrogenbecauseitdoesnotburn.Thegas-containingenvelopesofearlyairshipsusedcottonfabricimpregnatedwithrubber,acombinationthatwaseventuallysupersededbysyntheticfabricssuchasneopreneandDacron.

ThefirstsuccessfulairshipwasconstructedbyHenriGiffardofFrancein1852.Giffardbuilta160-kg(350-pound)steamenginecapableofdeveloping3horsepower,sufficienttoturnalargepropellerat110revolutionsperminute.Tocarrytheengineweighthefilledabag44metres(144feet)longwithhydrogenand,ascendingfromtheParisHippodrome,flewataspeedof10km(6miles)perhourtocoveradistanceofabout30km(20miles).

In1872aGermanengineer,PaulHaenlein,firstusedaninternal-combustionengineforflightinanairshipthatusedliftinggasfromthebagasfuel.In1883

engineforflightinanairshipthatusedliftinggasfromthebagasfuel.In1883AlbertandGastonTissandierofFrancebecamethefirsttosuccessfullypoweranairshipusinganelectricmotor.AlbertoSantos-Dumont,aBrazilianlivinginParis,setanumberofrecordsinaseriesof14nonrigid,gasoline-poweredairshipsthathebuiltfrom1898to1905.

Thefirstrigidairship,withahullofaluminumsheeting,wasbuiltinGermanyin1897,butthemostsuccessfuloperatorofrigidairshipswasFerdinand,Count(Graf)vonZeppelin,aretiredGermanarmyofficer.Hisfirstcompletedairship,theLZ-1(forLuftschiffZeppelin1),madeitsinitialflightfromafloatinghangaronLakeConstance,nearFriedrichshafen,Ger.,onJuly2,1900.Thistechnicallysophisticatedcraft,128metres(420feet)longand11.6metres(38feet)indiameter,hadanaluminumframeof24longitudinalgirderssetwithin16transverserings.Beneaththecraftakeellikestructureconnectedtwoexternalcars,eachofwhichcontaineda16-horsepowerenginegearedtotwopropellers.Aslidingweightsecuredtothekeelaffordedverticalcontrolbyraisingorloweringthenose,whilerudderswereprovidedforhorizontalcontrol.Thecraftattainedspeedsapproaching32km(20miles)perhour.

TheairshipsHindenburgandGrafZeppelinovertheReichstag,Berlin,Germany,March28,1936.EncyclopædiaBritannica,Inc.

ZeppelincontinuedimprovinghisdesignsthroughWorldWarI,whenmanyofhisairships(calledzeppelins),whichcouldattainhigheraltitudesthantheairplanesthenavailable,wereusedtobombParisandLondon.AirshipswerealsousedbytheAlliesduringthewar,chieflyforantisubmarinepatrol.AnumberofzeppelinsweredistributedtotheAlliedcountriesasapartofpostwarreparationsbyGermany.

Inthe1920sand’30sairshipconstructioncontinuedinEuropeandtheUnitedStates.ABritishdirigible,theR-34,madearound-triptransatlanticcrossinginJuly1919.In1926anItaliansemirigidairshipwassuccessfullyusedbyRoaldAmundsen,LincolnEllsworth,andGeneralUmbertoNobiletoexploretheNorthPole.In1928theGrafZeppelinwascompletedbyZeppelin’ssuccessor,HugoEckener,inGermany.Beforeitwasdecommissionednineyearslaterithadmade590flights,including144oceancrossings.andhadflownmorethan1.6millionkm(1millionmiles).In1929thecraftcoveredabout34,600km(21,500miles)inaworldflightthatwascompletedinanelapsedtimeofapproximately21days.

In1936GermanyinauguratedaregulartransatlanticpassengerservicewiththeGrafZeppelinandthegiantdirigibleHindenburg.Despitetheseachievements,airshipswerevirtuallyabandonedinthelate1930sbecauseoftheircost,theirslowspeed,andtheirintrinsicvulnerabilitytostormyweather.Inaddition,asuccessionofdisasters—thebestknownbeingtheexplosionofthehydrogen-filledHindenburgin1937—coupledwithadvancesinheavier-than-aircraftinthe1930sand’40smadedirigiblescommerciallyobsoleteformostapplications.

THEHINDENBURGDISASTER

Thelargestrigidairshipeverconstructed,theHindenburgwaslaunchedatFriedrichshafen,Ger.,inMarch1936.A245-metre-(804-foot-)longconventionalzeppelindesign,itwaspoweredbyfour1,100-horsepowerdieselengines,givingitamaximumspeedof135km(84miles)perhourandacruisingspeedof126km(78miles)perhour.Thoughitwasdesignedtobefilledwithheliumgas,theairshipwasfilledwithhighlyflammablehydrogenowingtoexportrestrictionsonheliumimposedbytheUnitedStatesagainstNaziGermany.

In1936theHindenburginauguratedcommercialairserviceacrosstheNorthAtlanticbycarrying1,002passengerson10scheduledroundtrips

betweenGermanyandtheUnitedStates.OnMay6,1937,whilelandingatLakehurst,N.J.,onthefirstofitsscheduled1937transatlanticcrossings,theHindenburgburstintoflamesandwascompletelydestroyed.Thirty-sixofthe97personsaboardwerekilled.Thefirewasofficiallyattributedtoadischargeofatmosphericelectricityinthevicinityofahydrogengasleakfromtheairship,thoughatthetimeitwasspeculatedthatthedirigiblewasthevictimofananti-Naziactofsabotage.TheHindenburgdisastermarkedtheendoftheuseofrigidairshipsincommercialairtransportation.

TheZeppelinairshipworksweredestroyedbyAlliedbombingduringWorldWarII,andbuildingofthehugerigidairshipswasneverresumed.In1993,descendantcompaniesofLuftschiffbau-ZeppelinfoundedZeppelinLuftschifftechnikGmbH,whichbuilttheZeppelinNT(“NewTechnology”),asmaller(75-metre,or250-foot)helium-filledairshipthatin2001begantooffershortsightseeingtripsoverLakeConstanceandotherlocations.

CHAPTER3THEINVENTIONOFTHEAIRPLANE

OntheeveningofSept.18,1901,WilburWright,a33-year-oldbusinessmanfromDayton,Ohio,addressedadistinguishedgroupofChicagoengineersonthesubjectof“SomeAeronauticalExperiments”thathehadconductedwithhisbrotherOrvilleWrightovertheprevioustwoyears.“Thedifficultieswhichobstructthepathwaytosuccessinflyingmachineconstruction,”henoted,“areofthreegeneralclasses”:

1.Thoserelatingtotheconstructionofthesustainingwings.2.Thoserelatingtothegenerationandapplicationofthepowerrequired

todrivethemachinethroughtheair.3.Thoserelatingtothebalancingandsteeringofthemachineafteritis

actuallyinflight.Thisclearanalysis—theclearestpossiblestatementoftheproblemof

heavier-than-airflight—addressedthethreecentralproblemsthathadtobesolvedinordertobringabouttheinventionoftheairplane:thedynamicreactionofliftingsurfaces(orwings),thedesignofabsolutelyreliableenginestoproducesufficientpowertopropelanairframe,andthecontrollingofflightinthreedimensions.OncetheWrightbrothershaddemonstratedthatthebasictechnicalproblemshadbeenovercomeatthestartofthe20thcentury,militaryandcivilaviationdevelopedquickly.

THEPROBLEMOFLIFT

Thedreamofhumanflightmusthavebegunwithobservationofbirdssoaringthroughthesky.Formillennia,however,progresswasretardedbyattemptstodesignaircraftthatemulatedthebeatingofabird’swings.Thegenerationsofexperimentersanddreamerswhofocusedtheirattentiononornithopters—machinesinwhichflappingwingsgeneratedbothliftandpropulsion—contributednothingsubstantialtothefinalsolutionoftheproblemsblockingtheroutetomechanicalflight.

Thus,thestoryoftheinventionoftheairplanebeginsinthe16th,17th,and18thcenturies,withthefirstseriousresearchintoaerodynamics—thestudyoftheforcesoperatingonasolidbody(forinstance,awingwhenitisimmersedinastreamofair).LeonardodaVinciandGalileoGalileiinItaly,ChristiaanHuygensintheNetherlands,andIsaacNewtoninEnglandallcontributedtoanunderstandingoftherelationshipbetweenresistance(drag)andsuchfactorsasthesurfaceareaofanobjectexposedtothestreamandthedensityofafluid.SwissmathematiciansDanielBernoulliandLeonhardEulerandBritishengineerJohnSmeatonexplainedtherelationshipbetweenpressureandvelocityandprovidedinformationthatenabledalatergenerationofengineerstocalculateaerodynamicforces.

EnglishaeronauticpioneerGeorgeCayleyestablishedthemodernnotionofafixed-wingaircraftin1799,andhedesignedaglider(showninthedrawing)thatwassafelyflownbyhisreluctantservantin1853inthefirstrecordedsuccessfulmannedflight.LibraryofCongress,

Washington,D.C.(neg.no.LC-DIG-ppmsca-02521)

GeorgeCayley,anEnglishbaronet,bridgedthegapbetweenphysicaltheory,engineeringresearch,andtheage-olddreamofflight.Hegatheredcriticalaerodynamicdataofvalueinthedesignofwingedaircraft,usinginstrumentsdevelopedinthe18thcenturyforresearchintoballistics.Cayleywasalsoapioneerofaircraftdesign,explainingthatasuccessfulflyingmachinewouldhaveseparatesystemsforlift,propulsion,andcontrol.Whilehedidproducedesignsforornithopters,hewasthefirstexperimentertofocusonfixed-wingaircraft.

Cayleyfoundthesecretsofliftintheshapeofabird’swing,surmisingthatanarched,orcambered,wingwouldproducegreaterliftthanaflatwingbecauseoflowerpressureontopofthecurvedsurface.Hisobservationsofbirdsinflightledhimtorecognizethesuperiorityofrelativelylongandnarrow(inmodernterminology,high-aspect-ratio)wingsforsoaring.Asapracticalmatter,however,hedesignedbiplaneandmultiplanewings(thefirstoftheirkind)asameansofprovidingmaximumsurfaceareainastrongandeasilybracedstructure.

AddressingthefirstmeetingoftheAeronauticalSocietyofGreatBritainin1866,FrancisH.WenhamprovidedaconciseandforcefulrestatementofCayley’smostimportantideasregardingwings.Fiveyearslater,incooperationwithJohnBrowning,Wenhambuiltthefirstwindtunnel,adevicethatwouldhaveaprofoundeffectonthestudyofwingsandthedevelopmentofimprovedairfoils.HoratioPhillips,afellowmemberoftheAeronauticalSociety,developedanevenmoreeffectivewindtunneldesign,andhepatented(1884)atwo-surface,cambered-airfoildesignthatprovidedthefoundationformostsubsequentworkinthefield.

Beginninginthe1870s,OttoLilienthal,aGermanmechanicalengineer,undertookthemostimportantstudiesofwingdesignsincethetimeofCayley.Hisdetailedmeasurementsoftheforcesoperatingonacamberedwingatvariousanglesofattackprovidedprecisebitsofdataemployedbylaterexperimenters—including,intheUnitedStates,theengineerOctaveChanuteandtheWrightbrothers—tocalculatetheperformanceoftheirownwings.Havingpublishedtheresultsofhisresearch,Lilienthaldesigned,built,andflewaseriesofmonoplaneandbiplanegliders,completingasmanyas2,000flightsbetween1890andthetimeofhisfatalglidercrashinAugust1896.

Attheoutsetoftheirownaeronauticalexperiments,theWrightbrotherscarefullystudiedtheworkoftheirpredecessorsanddecidedthattherewaslittle

carefullystudiedtheworkoftheirpredecessorsanddecidedthattherewaslittleneedforthemtofocusonwingdesign.“Menalreadyknowhowtoconstructwings…,”Wilburexplainedin1901,“whichwhendriventhroughtheairatsufficientspeedwillnotonlysustainthemselvesbutalsothatoftheengine,andoftheengineeraswell.”

Twoyearsofexperimentingwithgliders,however,demonstratedtheneedtopayconsiderablymoreattentiontowingdesign.BeginninginNovember1901,theWrightbrothersusedawindtunneloftheirowndesigntogatherinformationthatenabledthemtocalculatethevaluesofliftanddragforanentireseriesofairfoilsatvariousanglesofattackandtomeasuretheperformanceofwingswithdifferingaspectratios,tipshapes,andotherdesignfeatures.ThatinformationculminatedintheWrightgliderof1902,abreakthroughmachinewhosewingdesignenabledtheWrightbrotherstotakethefinalstepstotheinventionoftheairplane.

THEPROBLEMOFPROPULSION

Atthebeginningofthe19thcentury,sustainedpoweredheavier-than-airflightremainedanimpossibilitybecauseofthelackofsuitablepowerplants.Theleveloftechnologythatwouldpermitevenlimitedpoweredflightlayoveracenturyinthefuture.Clockworkmechanismsandothersortsofspring-poweredsystemswereclearlyunsuitableforhumanflight.Whileelectricitypoweredseveralairshipsduringthelastquarterofthecentury,thepoorpower-to-weightratioofsuchsystemsmadeitdifficulttoimagineanelectricallypropelledairplane.

Theaeronauticalpotentialofpropulsionsystemsrangingfromhot-airenginestogunpowdertocompressedairandeventocarbonic-acidpowerplantswasdiscussedduringthecourseofthecentury.TheAustralianLawrenceHargrave,inparticular,experimentedwithcompressed-gaspropulsionsystems.Nevertheless,steamandinternal-combustionenginesquicklyemergedasthechoiceofmostseriousexperimenters.Asearlyas1829,F.D.Artingstallconstructedafull-scalesteam-poweredornithoptor,thewingsofwhichweresmashedinoperationjustbeforetheboilerexploded.AlightweightsteamenginedevelopedbytheEnglishpioneerFrederickStringfellowin1868topoweratriplanemodelaircraftsurvivesinthecollectionoftheSmithsonianInstitution,Washington,D.C.

Anartist’srenditionoftheflightofSamuelPierpontLangley’ssteam-poweredunmannedaerodromeNo.5onMay6,1896,asseenfromaboveandbelow.©Photos.com/Jupiterimages

RussianAlexandrMozhaysky(1884),EnglishmanHiramMaxim(1894),andFrenchmanClémentAder(1890)eachjumpedfull-scalesteam-poweredmachinesoffthegroundforshortdistances,althoughnoneofthesecraftwascapableofsustainedorcontrolledflight.IntheUnitedStates,SamuelPierpontLangleyachievedthefirstsustainedflightsin1896whenhelaunchedtwoofhisrelativelylargesteam-poweredmodelaircraftonaerialjourneysofuptothree-quartersofamile(1.2km)overthePotomacRiver.

Astheendofthe19thcenturyapproached,theinternal-combustionengineemergedasanevenmorepromisingaeronauticalpowerplant.Theprocesshadbegunin1860,whenÉtienneLenoirofBelgiumbuiltthefirstinternal-combustionengine,fueledwithilluminatinggas.InGermany,NikolausA.Ottotookthenextstepin1876,producingafour-strokeengineburningliquidfuel.GermanengineerGottliebDaimlerpioneeredthedevelopmentoflightweighthigh-speedgasolineengines,oneofwhichhemountedonabicyclein1885.GermanengineerKarlBenzproducedthefirsttrueautomobilethefollowing

GermanengineerKarlBenzproducedthefirsttrueautomobilethefollowingyear,asturdytricyclewithseatingfortheoperatorandapassenger.In1888DaimlerpersuadedKarlWoelfert,aLutheranministerwholongedtofly,toequipanexperimentalairshipwithasingle-cylindergasolineenginethatdevelopedallofeighthorsepower.Theinitialtestwasmarginallysuccessful,althoughtheopen-flameignitionsystempresentedanobviousdangertoahydrogen-filledairship.Infact,Woelfertperishedwhenaninternal-combustionenginefinallydidsetamuchlargerairshiponfirein1897.

Atthebeginningoftheircareerinaeronautics,theWrightbrothersrecognizedthatautomotiveenthusiastswereproducingeverlighterandmorepowerfulinternal-combustionengines.Thebrothersassumedthatiftheirglidingexperimentsprogressedtothepointwheretheyrequiredapowerplant,itwouldnotbedifficulttobuyorbuildagasolineenginefortheiraircraft.

Theywereessentiallycorrect.Havingflowntheirsuccessfulgliderof1902,theWrightbrotherswereconfidentthattheirwingswouldlifttheweightofapoweredflyingmachineandthattheycouldcontrolsuchacraftintheair.Moreover,threeyearsofexperiencewithgliders,andtheinformationgatheredwiththeirwindtunnel,enabledthemtocalculatethepreciseamountofpowerrequiredforsustainedflight.Unabletointerestanexperiencedmanufacturerinproducinganenginemeetingtheirrelativelynarrowpower-for-weightspecifications,thebrothersdesignedandbuilttheirownpowerplant.

CharlesTaylor,amachinistwhomthebrothersemployedintheirbicycleshop,producedafour-cylinderenginewithacastaluminumblockthatproducedroughly12.5horsepoweratatotalweightofsome90kg(200pounds),includingfuelandcoolant.Itwasbynomeansthemostadvancedorefficientaeronauticalpowerplantintheworld.Langley,whowasalsobuildingafull-scalepoweredflyingmachine,spentthousandsofdollarstoproduceafive-cylinderradialenginewithatotalweightequaltothatoftheWrightenginebutdeveloping52.4horsepower.LangleyproducedanenginefarsuperiortothatoftheWrightbrothers—andanairplane,theaerodromeNo.6,thatfailedtoflywhentestedin1903.TheWrightbrothers,ontheotherhand,developedanenginethatproducedexactlythepowerrequiredtopropeltheirflyerof1903—theworld’sfirstairplanetodemonstratesustainedflight.

OrvilleWrightbeginningthefirstsuccessfulcontrolledflightinhistory,atKillDevilHills,NorthCarolina,Dec.17,1903.CourtesyofNationalAirandSpaceMuseum,SmithsonianInstitution,Washington,D.C.

THEWRIGHTBROTHERSATKITTYHAWK

ThefirstpoweredairplanetodemonstratesustainedflightunderthefullcontrolofthepilotwastheWrightbrothers’flyerof1903.DesignedandbuiltbyWilburandOrvilleinDayton,Ohio,itwasassembledintheautumnof1903atacampatthebaseoftheKillDevilHills,nearKittyHawk,avillageontheOuterBanksofNorthCarolina.AfterafirstattemptfailedonDecember14,themachinewasflownfourtimesonDecember17,todistancesof120,175,200,and852feet(36.6,53.3,61,and260metres),respectively.ItisnowondisplayintheNationalAirandSpaceMuseumoftheSmithsonianInstitution,Washington,D.C.

The1903Wrightairplanewasanextremelystrongyetflexiblebracedbiplanestructure.Forwardofthewingswasatwin-surfacehorizontalelevator,andtotherearwasatwin-surfaceverticalrudder.Wingsparsandotherlong,straightsectionsofthecraftwereconstructedofspruce,whilethewingribsandotherbentorshapedpieceswerebuiltofash.Aerodynamicsurfaceswerecoveredwithafinelywovenmuslincloth.Theflyerwaspropelledbyafour-cylindergasolineengineoftheWrights’owndesignthatdevelopedsome12.5horsepowerafterthefirstfewsecondsofoperation.Theenginewaslinkedthroughachain-drivetransmissiontotwincontrarotatingpusherpropellers,whichitturnedatanaveragespeedof348rotationsperminute.

Thepilotlayonthelowerwingofthebiplanewithhishipspositioned

Thepilotlayonthelowerwingofthebiplanewithhishipspositionedinapaddedwoodencradle.Amovementofthehipstotherightorleftoperatedthe“wing-warping”system,whichincreasedtheangleofattackofthewingsononesideofthecraftanddecreaseditontheother,enablingthepilottoraiseorlowerthewingtipsoneithersideinordertomaintainbalanceortorollintoaturn.Asmallhandlevercontrolledtheforwardelevator,whichprovidedpitchcontrolandsomeextralift.Therearrudderwasdirectlylinkedtothewing-warpingsysteminordertocounteractproblemsofyawproducedbythewarpingofthewings.

TheWrightsknewthatitwouldbedifficulttooperateawheeledaircraftfromtheroughandsandysurfacewheretheyplannedtofly,sotheydecidedtolaunchtheirmachineintotheairwithasmoothrundowna60-foot(18-metre)-longmonorailtrack.Thelaunchrailconsistedoffour15-foot(4.5-metre)two-by-fours,thethinupperedgeofwhichwasprotectedbyametalcapstrip.Theairplanerandowntherailontwomodifiedbicyclewheelhubs.

Atthebeginningofeachflighttheairplanewaspositionedattheheadoftherail.Arestraininglineranfromaclipnearthepilot’spositionattheleadingedgeofthelowerwingtoastakedrivenintothegroundbehindthemachine.Theenginecouldnotbethrottled;ahandleveronlyallowedthepilottoopenorclosethefuelline.Inordertostarttheengine,acoilboxwasconnectedtothesparkplugs,andtwomenpulledthepropellersthroughtoturntheengineover.Whenthepilotwasready,hereleasedtherestrainingropewiththehandclip,andthemachinemoveddowntherail.

The1903machinewasneverflownafterDecember17.Whilesittingonthegroundafterthefourthflight,itwasflippedbyagustofwindandbadlydamaged.ShippedbacktoDayton,itwasreassembledandrepairedasneededfortemporaryexhibitionsbeforebeingputondisplayattheScienceMuseum,London,in1928.Thereitremainedfor20years,atthecentreofadisputebetweenOrvilleWrightandtheSmithsonianInstitutionoverclaimsthattheInstitution’sthirdsecretary,SamuelP.Langley,hadconstructedamachinecapableofflightpriortotheWrights’flightsofDecember1903.ThedisputeendedwithanapologyfromtheSmithsonianin1942,andtheflyerwastransferredpermanentlytotheInstitution’scollectionin1948,severalmonthsafterOrville’sdeath.

Thedesignofthepropellersforthe1903airplanerepresentedamuchmore

difficulttask,andamuchgreatertechnicalachievement,thanthedevelopmentoftheengine.Thepropellersnotonlyhadtobeefficientbuthadtoproduceacalculatedamountofthrustwhenoperatedataparticularspeedbytheengine.Itisimportanttorecognize,however,thatoncepoweredflighthadbeenachieved,thedevelopmentofmorepowerfulandefficientenginesbecameanessentialelementinthedrivetoimproveaircraftperformance.

THEPROBLEMOFCONTROL

Havingdecidedthatthedesignofwingsandthedevelopmentofapowerplantwerefairlywellinhand,theWrightbrothersfocusedontheelementofcontrol.Otherexperimentershadgivensomethoughttothesubject.Cayleywasthefirsttouseanelevatorforcontrolinpitch(directingthenoseupanddown).Throughoutthesecondhalfofthe19thcentury,airshipshadusedruddersforyawcontrol(directingthenosetotherightandleft).

Itwasfarmoredifficulttoconceiveofawaytocontrolanaircraftinroll(thatis,balancingthewingtipsorbankingtheaircraft).Moreover,mostexperimenterswereconvincedthattheoperatorofaflyingmachinewouldfinditdifficultorimpossibletoexercisefullcontroloveramachinethatwasfreetooperateinallthreeaxesofmotionatonce.Asaresult,farmorethoughthadbeengiventothemeansofachievingautomaticorinherentstabilitythantoactivecontrolsystems.

Cayley,forexample,suggesteddihedralwings(wingtipsangledupfromthemidpointofthewing)asameansofachievingameasureofstabilityinroll;healsorecommendedtheuseofapendulumtocontrolpitch.FrenchaviationpioneerAlphonsePenaudwasthefirsttoproduceaninherentlystableaircraft,thePlanophore(1871),whichfeaturedapusherpropellerpoweredbytwistedrubberstrands.Thehand-launchedmodelfeatureddihedralwingsforstabilityinrollandahorizontalsurfacesetataslightnegativeanglewithregardtothewingstoprovidestabilityinpitch.Withtheadditionofaverticalsurfaceforstabilityinyaw,thiswastheapproachtakenbyvirtuallyallexperimenterswithmodelaircraft,includingLangley.

Modelbuilderswereforcedtoemployautomaticstability,butthoseexperimenterswhobuiltandflewglidershadtodevelopactiveflightcontrols.Virtuallyallofthepre-Wrightbrothersgliderpilots,includingLilienthal,usedhang-glidingtechniques,inwhichthepilotshiftedhisweightinordertoalterthepositionofthecentreofgravityofthemachinewithregardtothecentreofpressure.Weightshiftingwasdangerousandlimiting,however.Ifsimple

pressure.Weightshiftingwasdangerousandlimiting,however.Ifsimplemovementsoftheoperator’sbodyweretohaveasignificantimpactonthemotionofthemachine,thewingareahadtobereasonablysmall.Thislimitedtheamountofliftthatcouldbegenerated.Moreover,itwasbynomeansdifficultforsuchanaircrafttoreachastallorsomeotheruncontrolledpositionfromwhichweightshiftingcouldnoteffectarecovery—asdemonstratedbythedeathsofLilienthal(1896)andtheEnglishexperimenterPercyPilcher(1899)inglidercrashes.

Determinedtoavoidthoseproblems,theWrightbrotherscreatedapositivecontrolsystemthatenabled(indeed,required)thepilottoexerciseabsolutecommandoverthemotionofhismachineineveryaxisandateverymoment.Othershadrejectedthatgoalbecausetheyfearedthatpilotswouldbeoverwhelmedbythedifficultyofcontrollingamachinemovinginthreedimensions.TheWrightbrothers,however,hadrecognizedhoweasilyandquicklyabicycleriderinternalizedthemotionsrequiredtomaintainbalanceandcontrol,andtheywerecertainthatitwouldbethesamewithanairplane.

OnJan.13,1908,FrenchaviatorHenriFarmanwontheGrandPrixd’Aviationforthefirstcircularflightofmorethan1km(0.6mile).LibraryofCongress,Washington,D.C.(neg.no.LC-DIG-ggbain-04183)

Recognizingthedangersinherentinattemptingtorelyoncontrolofthecentreofgravity,theWrightbrothersdevisedasystemtocontrolthemovementofthecentreofpressureonthewing.Theyachievedthisbyenablingthepilottoinduceatwistacrosstheupperandlowerwingsineitherdirection,thusincreasingtheliftononesideanddecreasingitontheother.Thistechnique,whichtheycalled“wingwarping,”solvedthecrucialproblemofroll.

whichtheycalled“wingwarping,”solvedthecrucialproblemofroll.Meanwhile,anelevator(ahorizontalsurfaceplacedatthefrontoftheaircraft)providedthemeansofpitchcontrol.WhentheWrightbrothersintroducedaruddertotheirdesignin1902,thisdevicewasusedtocompensateforincreaseddragonthepositivelywarpedsideoftheaircraft.In1905theydisconnectedtherudderfromthewingwarpingsystem,enablingthepilottoexerciseindependentcontrolinyawforthefirsttime.TheWrightflyerof1905isthereforeconsideredtobethefirstfullycontrollable,practicalairplane.

OTHERAVIATIONPIONEERS

TheworkoftheWrightbrothersinspiredanentiregenerationofflying-machineexperimentersinEuropeandtheAmericas.TheBrazilianexperimenterAlbertoSantos-Dumont,forinstance,madethefirstpublicflightinEuropein1906inhis14-bis.FrenchmanHenriFarmanmadehisfirstflightthefollowingyearintheFarmanIII,amachinebuiltbyGabrielVoisin.FarmanalsocompletedthefirstEuropeancircularflightofatleast1km(0.62mile)earlyin1908.OnJuly4,1908,theAmericanGlennHammondCurtiss,aleadingmemberoftheAerialExperimentAssociation(AEA),organizedbyAlexanderGrahamBell,wontheScientificAmericanTrophyforaflightof1kmintheAEAJuneBug.

TheSantos-Dumont,Voisin,andCurtissmachineswereallcanard(elevatoronthenose)biplaneswithpusherpropellersthatwereclearlyinspiredbywhatthedesignersknewoftheworkoftheWrightbrothers.

By1909radicalnewmonoplanedesignshadtakentotheair,builtandflownbymensuchastheFrenchpioneersRobertEsnault-PelterieandLouisBlériot,bothofwhomwereinvolvedinthedevelopmentofthe“stick-and-rudder”cockpitcontrolsystemthatwouldsoonbeadoptedbyotherbuilders.BlériotbroughttheearlyexperimentaleraofaviationtoanendonJuly25,1909,whenheflewhisTypeXImonoplaneacrosstheEnglishChannel.

AmericanaeronauticpioneerGlennHammondCurtisspilotedhisModelEflyingboatoverKeukaLake,nearHammondsport,N.Y.,in1912.LibraryofCongress,Washington,D.C.(neg.no.LC-DIG-ggbain-11555)

Thefollowingfiveyears,fromBlériot’sChannelflighttothebeginningofWorldWarI,wereaperiodofspectaculargrowthanddevelopmentinaviation.Concernedaboutthepotentialofmilitaryaviation,Europeanleadersinvestedheavilyinthenewtechnology,spendinglargesumsonresearchanddevelopmentandworkingtoestablishandsupporttheaircraftandengineindustriesintheirowncountries.Inadditiontopracticaldevelopmentsintheareasofpropulsionandaircraftstructuraldesign,thefoundationsofmodernaerodynamictheorywerelaidbyscientistsandacademicssuchasLudwigPrandtlofGermany.Withthepossibleexceptionofflyingboats,anareainwhichCurtisscontinuedtodominate,leadershipinvirtuallyeveryphaseofaeronauticshadpassedby1910fromtheUnitedStatestoEurope,whereitwouldremainthroughoutWorldWarI.

FrenchaviationpioneerRobertEsnault-Pelteriedesigned,built,andwasthefirsttoflytheR.E.P.No.2,in1908.LibraryofCongress,Washington,D.C.(neg.no.LC-DIG-ggbain-04136)

CHAPTER4PISTONSANDPROPELLERS

DuringWorldWarIseveralfarsightedEuropeanentrepreneurs,emboldenedbywartimeprogressinaviation,envisionedthepossibilitiesofpostwarairlinetravel.Formanymonthsafterthewar,normalrailtravelinEuroperemainedproblematicandirregularbecauseoftheshortageofpassengerequipmentandthedestructionoftracksandbridges.Inaddition,chaoticpoliticalconditionsincentralandeasternEuropeoftendisruptedschedules.Thesituationopenedmanypossibilitiesforlaunchingairlineroutes.

Althoughfewairfieldsexisted,aircraftofthepostwareracouldanddiduserelativelyshortsodrunwaysforyears,meaningthatlocatingsuitableairportsnearmostcitieswasnottheformidableengineeringchallengethatemergedinsubsequentdecades.Characteristically,organizersofthefirstpostwarairlinesreliedonstocksofinexpensivesurplusmilitaryplanes,especiallybombers,suchastheDeHavillandDH-4,thatcouldbemodifiedtoaccommodatepassengersandmail.Twobasictypesofpistonenginespoweredthetypicalfabric-coveredbiplanesoftheearlypostwarera.In-lineengines,withcylindersalignedonebehindtheotherorpositionedintwobanksinaV-typeinstallation,requiredaradiatorandthecirculationofaliquidcoolant.Radialengines,withcylindersarrangedinacirclearoundthecrankshaft,hadnumeroussmallfinsonthecylinderthatradiatedheattothepassingairstreaminordertokeeptheenginecool.Theserelativelystraightforwardpiston-enginedesignsmadelong-rangeflightspossibleandopenedaneweraofpassengertravel.

THEHEADLINERS

AlthoughairlinesrannewspaperadvertisementsafterWorldWarI,thebiggestaviationheadlinesbelongedtofliersinrelativelyprimitivepiston-engineaircraftthatchallengedtheAtlanticandtranscontinentaldistances.InMay1919aU.S.NavyCurtissNC-4(successortotheCurtissModelEflyingboat)madeitfromNewfoundlandtoPortugalbywayoftheAzoresIslandsbeforeflyingontoGreatBritain,compiling54hours31minutesintheairoverits23-daytrip.Thefollowingmonth,formerBritishRoyalAirForce(RAF)pilotsJohnAlcockandArthurBrownmadethefirstnonstopcrossingoftheAtlantic,requiring16hours28minutesforthejourneyfromNewfoundlandtoIrelandinaVickersVimybomber.

By1924theU.S.Armyhadcompletedplanstomakethefirstaerialcircumnavigationoftheworld,sendingaquartetofsingle-engineDouglas“WorldCruisers”westwardtowardAsia.Thesefabric-coveredbiplanesfeaturedinterchangeablelandinggear—replacingwheelswithfloatsforwaterlandings.OneplanecrashedinAlaska,forcingthetwo-mancrewtohikeoutofasnowboundwilderness.Neartheendoftheexpedition,asecondaircraft,enroutetoIceland,wentdownbetweentheOrkneyandFaroeislands.WithsupportfromtheU.S.Navy,U.S.StateDepartment,andoverseasAmericanofficialsduringanodysseyof37,622km(23,377miles)thatconsumed175days,theremainingpairofplanesarrivedbackinSeattle.AllthishappenedbeforeCharlesLindbergh,flyingasingle-engineRyanmonoplane,madehisnonstopsoloflightin33hours30minutesfromNewYorktoParisin1927.Lindbergh’sflight,inparticular,demonstratedtheessentialreliabilityofimprovedradialengines.

TheVickersVimyplaneusedbyJohnAlcockandArthurBrowninthefirstnonstoptransatlanticflight.

InBritain,overlandflightsconnectingcolonialinterestsdownthelengthofAfricadrewconsiderableattention.DepartingLondon,anotherpairofex-RAFpilotsbattledcapriciouswinds,suddenstorms,equatorialupdrafts,andassortedadventuresbeforearrivingatCapeTownafter45daysandthreeplanes.AlanCobhamrepeatedthefeatinasingle-enginecommercialplane,surveyingarouteforImperialAirways,Ltd.,from1925to1926.OtherBritishpilotsperseveredinreachingAustraliabywayofIndia(brothersRossandKeithSmith,1919)andacrossthePacific(CharlesKingsfordSmithandCharlesUlm,1928).Thechallengeofpolarflightsalsoengagedanumberofdaringfliers.PilotingaFokkertrimotor,RichardByrdmadeclaimtothefirstflightovertheNorthPolein1926,followedbyhispioneeringexpeditionwithaFordMotorCompanytrimotorovertheSouthPolein1929.

The1930sbroughtanewroundofrecordflightsbyAmericans.In1931,withnavigatorHaroldGatty,WileyPostpilotedaLockheedVega5Bmonoplane(namedWinnieMaeforPost’sdaughter)aroundtheworldinslightlylessthan8days16hours.Twoyearslater,withtheaidofanautopilot,Postbrokehisworldrecordduringasoloflightof7days19hours.In1932AmeliaEarhartbecamethefirstwomantocompleteasolotransatlanticflight.Fiveyearslater,duringaglobalattempt,shedisappearedsomewhereoverthePacific.AviatorandindustrialistHowardHughes,pilotingatwin-engineLockheedModel14(similartoEarhart’sLockheed5BVegaairplane)withafour-mancrew,completedaglobalflightin1938intherecordtimeofslightlymorethan3days19hours.Flightslikethesedemonstratedaviation’sabilitytoovercomegeographicbarriersandshrinktime-distancerelationships.

LINDBERGHCROSSESTHEATLANTIC

CharlesA.Lindbergh’searlyyearswerespentchieflyinLittleFalls,Minn.,andinWashington,D.C.,wherefor10yearshisfatherrepresentedthe6thdistrictofMinnesotainCongress.HisformaleducationendedduringhissecondyearattheUniversityofWisconsininMadison,whenhisgrowinginterestinaviationledtoenrollmentinaflyingschoolinLincoln,Neb.,andthepurchaseofaWorldWarICurtissJenny,withwhichhemadestunt-flyingtoursthroughSouthernandMidwesternstates.AfterayearatthearmyflyingschoolsinTexas(1924–25),hebecameanairmailpilot(1926),flyingtheroutefromSt.Louis,Mo.,toChicago.DuringthisperiodheobtainedfinancialbackingfromagroupofSt.Louisbusinessmentocompeteforthe$25,000prizeofferedforthefirstnonstop

flightbetweenNewYorkandParis.InthemonoplaneSpiritofSt.Louishemadethe3,610-mile(5,810-km)flightin33.5hoursonMay20–21,1927.OvernightLindberghbecameafolkheroonbothsidesoftheAtlantic,andpublicenthusiasmforflyingandaircraftexploded(aphenomenondubbedthe“Lindberghboom”).

Lindbergh’splanewasaRyanNYP(“NewYorktoParis”),modifiedfromtheRyanM2,asingle-engine,high-wingmonoplanedesignedformailandpassengerservicebyT.ClaudeRyanofRyanAirlines,SanDiego,Calif.Instandardconformationtheairplanewouldhaveseatedfivepeople;extrafueltanksintheSpiritofSt.Louisoccupiedmuchofwhathadbeencabinspace.Thewindshieldwasreplacedbyanextensionofthenosecowling,sothatLindberghhaddirectvisiononlyfromthesidewindows,relyingonaperiscopetoseestraightahead.Therewasnoradio.AWrightWhirlwindair-cooledradialenginedevelopedamaximumof237horsepower.Wingspanofthecraftwas46feet(14metres)andlength27feet8inches(8.4metres).Fuelcapacitywiththeextratankswas450gallons;topspeedatsealevel,whenloaded,was120miles(200km)perhour,andrangewas4,100miles(6,600km).

TheSpiritofSt.LouiswasreturnedfromEuropetotheUnitedStatesaboardship,andLindberghflewitextensivelythroughoutNorth,Central,andSouthAmericatopromoteinterestinaeronauticsbeforedonatingittotheSmithsonianInstitution.ItresidestodayintheNationalAirandSpaceMuseum,keepingcompanywiththeWrightbrothers’1903flyer.

Inadditiontolong-distancerecords,speedrecordscontinuedtorise.Forexample,theSchneiderTrophyraces,conductedinEuropebetween1913and1931,pittedsingle-engineracingplanesequippedwithfloatsagainsteachother.Withentrantscarryingthecoloursoftheirrespectivecountries,considerableinternationalprestigeandtechnologicalrecognitionwasattachedtotheoutcome.Designersfocusedonhigh-performanceenginesandstreamlinedfuselages.Bytheearly1930s,successfulBritishracersfromSupermarine,reachingabout340miles(550km)perhour,werecontributingtothedesignsthatledtothelegendarySpitfirefightersofWorldWarII.Behindtheheadlines,thecollectivetechnologyandoperationalknow-howoftherecord-seekerscontributedtomodernairlinetravel.

THEFIRSTAIRLINES

Oneoftheearliestairlineorganizations,aBritishgroupcalledAirTransportandTravel,Ltd.,acquiredseveralAircoD.H.4aVIIIsingle-engineplanes(designedbyGeoffreyDeHavilland),poweredby350-horsepowerEagleV-typeenginesfromRolls-Royce,Ltd.,andmodifiedthemtoincludeanenclosedcrampedspaceinthefuselagewithroomfortwoadventurouspassengers.Thepilot’scockpit,atopthefuselage,remainedopen.Thecompany’sinauguralflightoccurredonAug.25,1919,whentheplaneflewfromLondontoPariswithitssolepassenger,anenterprisingnewspaperreporter.

Theservicecaughtonandcompetitorssoonfollowed.HandleyPageTransport,Ltd.,madeuseofthemanufacturingcompany’swartimetwin-enginebombers,convertingthemtohaulupto14passengers,wholoungedincomfortablewickerchairs.Theseslowbutroomyaircraftestablishedatraditionofornatelyembellishedinteriorsandspacioussurroundings—atthesacrificeofaerodynamicefficiencyandhighspeeds—onearlyEuropeanairlines.Giventhelackofnavigationalaidsandtheprimitiveinstrumentationoftheera,accidentsinvariablyoccurred,andpassengersbecameusedtodelayscausedbythenotoriouslyfoulwinterweatherinEngland.Pilotshadtodependonluckandquickthinkingwhentheywerecaughtinunexpectedatmosphericconditions.ApproachingLondoninthefog,oneBritishpilotsuddenlyrealizedhehaddriftedtooclosetothegroundwhenachurchsteepleloomedoutofthemistathiseyelevel.Fortunately,henoticedthatexpresstrainsspeedingtowardLondonleftavisiblefurrowinthedensefogbank,andhegratefullyfollowedthisphenomenonintothecity,wherehefoundimprovedconditionsforlanding.By1924,withgovernmentsupport,independentairlinesinBritainhadconsolidatedintooneentity,ImperialAirways,Ltd.,asameanstocompetewiththeheavilysubsidizedFrenchairlinesinEurope.

TheBritishalsousedairlinestoknittogetherelementsoftheirfar-flungempire.Duringthe1920s,ImperialAirwaysmountedoperationsinAfricaandtheMiddleEast.Acrosstracklessstretchesofsparselyinhabiteddesert,creativesurveyorcrewsshrewdlydrovecarsandtruckstocreateavisibletrackforpilotstofollow;insomeareas,theyplowedfurrowsintheground.Intothelate1930s,standardequipmentontheserouteswasthestatelyHandleyPageH.P.42,abiplanehavingawingspanof40metres(130feet)andfour490-horsepowerBristolJupiterengines.Dependingonseatingarrangements,24to38passengerscruisedalongatabout160km(100miles)perhourovertheplane’s800-km(500-mile)range.Theairlinescheduledseveraldays(includingovernightstops)

totravelfromLondontotheCapeofSouthAfricabyair,comparedwithsomeweeksbysteamship.Theroute’sclientelecharacteristicallyincludedwell-placedcolonialofficialsandwealthybusinesstravelerswhoexpectedfirst-classservice.Consequently,theH.P.42’spassengercabinfeatureddimensionsnearlyequaltothesizeofaPullmanrailwaycar,andpatronsappreciatedplushwall-to-wallcarpetingandastand-upbar.Attentivestewardsservedseven-coursemeals.

ImperialAirways,Ltd.,employeesrefuelingaHandleyPageH.P.42airlineratSemakhontheSeaofGalilee,1931.LibraryofCongress,Washington,D.C.(neg.no.LC-M32-4239)

FrancealsohadterritorialpossessionsinAfricaaswellasimportantbusinessinterestsinLatinAmerica.Consequently,FrenchairlinesranalongtheMediterraneancoastofSpain,overtoMorocco,anddownthewesterncoastofAfricaasfarasDakar,Seneg.TheroutestookplanesandcrewsoversomeofthemostinhospitableareasofnorthwestAfrica,wherenativetribesmenmaintainedstrongprejudicesagainstEuropeans.Forceddowninthedesert,someFrenchairmenwerekilled,andotherswerecartedoffincagestobeheldashostagesforransom.AntoinedeSaint-Exupéry,thefamedaviatorandauthor,becamesuccessfulasafieldmanagerinAfrica,donningnativegarbandnegotiatingpeacewithlocaltribalchiefs.AbewilderingvarietyofplanesfromHenriFarman,Louis-CharlesBréguet,PierreLatécoère,andothersequippeddomesticandinternationalairlines.Bythe1930s,theFrenchhadalsoestablishedoperationsinSouthAmericaandbeguntoexperimentwithmaildeliveriesacrosstheSouthAtlantic.

In1919theNetherlandsorganizedanewairline,KLM,andbeganservicebetweenLondonandAmsterdamusingaircraftbuiltbyAnthonyFokker.(KLMnowproudlyclaimsthetitleoftheworld’soldestcontinuouslyoperating

nowproudlyclaimsthetitleoftheworld’soldestcontinuouslyoperatingairline.)By1930,KLMofferedweeklyservicetoBatavia(nowJakarta),thecolonialcapitaloftheDutchEastIndies,andcompetedwithImperialAirwaysintheFarEast.PioneeringairservicesalsosprangupinAfrica,Asia,andAustralia.

Germany,preventedbytheTreatyofVersaillesfromdevelopingmilitaryaircraft,pouredconsiderableeffortintociviliandesigns.TheGermangovernmentalsogaveitsblessingtotheexpansionistplansofDeutscheLuftHansa(nowDeutscheLufthansaAg),formedin1926.HugoJunkers’sfirmsuppliedasteadystreamoflowwingsingle-andthree-engineplanes,cladincorrugatedmetal,thatsurvivedfordecadesinobscurecornersoftheworld.Meanwhile,GermanairlinersbecameregularcallersthroughoutcentralandeasternEurope,withroutesthatextendedasfareastasMoscow.OthersegmentsofLufthansacoveredScandinaviaandtheBaltic;stillothersrantotheeasternMediterraneananddowntoBaghdad.Bythemid-1930s,GermanyoperatedthelargestcommercialairlinenetworkinEurope.

OutofthechaosofWorldWarI,imperialRussiaemergedastheUnionofSovietSocialistRepublics.Thecommunistregimesoonseizedonaviationasaniconofanewtechnicalworldtobeshapedbytheindustrialproletariat.Aeroflot,thestateairline,notonlyservedpropagandapurposesbutsubsequentlyemergedasanindispensablemediumforrapidtransportationandavisiblemeansofknittingtogetherthesprawling,divergentregionsoftheSovietUnion.AlthoughtheSovietregimeoccasionallypurchasedwesterntechnology,itscommissarsemphasizedtheuseofindigenousequipmentinordertobefreeofinvidiouscapitalisticinfluences.Consequently,Sovietengineandaircraftdesignbureaus,likethatrunbyOlegAntonov,turnedouthundredsofplanesforuseonAeroflot’svastinternalairwaysystem.

FROMAIRMAILTOAIRLINESINTHEUNITEDSTATES

AlthoughtheAmericanexperiencesometimesreflectedEuropeantrends,italsodemonstratedcleardifferences.UndertheauspicesoftheU.S.PostalService,anairmailoperationwaslaunchedin1918asawartimeefforttostimulateaircraftproductionandtogenerateapooloftrainedpilots.UsingCurtissJN-4H(“Jenny”)trainersconvertedtomailplanes,theearlyservicefloundered.Afterthewar,shrewdairmailbureaucratsobtainedlargerAmerican-builtDeHavillandDH-4biplaneswithliquid-cooledLibertyenginesfromsurplusmilitarystocks.Theirtopspeedof80miles(130km)perhoursurpassedthe75

miles(120km)perhouroftheJenny,allowingmailplanestobeatrailwaydeliverytimesoverlongdistances.By1924,coast-to-coastairmailservicehaddeveloped,usinglightbeaconstoguideopen-cockpitplanesatnight.CorrespondencefromNewYorknowarrivedontheWestCoastintwodaysinsteadoffivedaysbyrailway.Thissavingsintimehadadistinctimpactonexpeditingtheclearanceofchecks,interest-bearingsecurities,andotherbusinesspaperwithatime-sensitivevalueintransferbetweenbusinessesandfinancialinstitutions.

Havingestablishedaworkableairmailsystemandaconsiderableclientele,thePostalServiceyieldedtocongressionalpressuresand,withtheContractAirMailActof1925,turnedoverthemailservicetoprivatecontractors.Thefollowingyear,theAirCommerceActestablishedabureautoenforceproceduresforthelicensingofaircraft,engines,pilots,andotherpersonnel.Theformeractstimulateddesignandproductionofadvancedplanestocompetewithrivalcarriers;thelatterreassuredinsurancecompanies,privateinvestors,andbanksthatsafetystandardswouldbeenforced.Withtheseelementsinhand,Americanaviationrapidlyprogressed.Ironically,atthesametimethatEuropeancountriesorganizedsubsidizednationalflaglinesandfollowedpracticesthatoftendiscouragedinnovationinthedesignofairliners,theUnitedStatesturnedovercivilaviationtocommercialoperators,whereaggressivecompetitionacceleratedsignificantdevelopmentsinaviationtechnologyandaircraftperformance.

Foronething,manufacturersofairplanemotorsbeganasignificantperiodofdevelopmentinmodernpistonengines.Becauseliquid-cooledin-lineenginesofferedlessfrontalsurface,theywereoftenfavouredbymilitarydesigners.Withtheseengines,aircraftcouldbestreamlinedtoimprovespeedbutwithatrade-offincomplexityandweightbecauseoftherequisitecoolant,coolantlines,radiator,andassociatedpumps.Air-cooledradialdesigns,incontrast,achievedrelativesimplicity,reliability,andcomparativelylightweightatthecostofmoreairresistance(creatingdrag)becauseoftheirbluntshape.In1928,theNationalAdvisoryCommitteeforAeronautics(NACA)announceditsfamouscowlingforradialengines.Itnotonlysmoothedairflowaroundtheengine,substantiallyreducingdrag,butalsoenhancedthecoolingofthecylinders.Withtheirdependabilityandeaseofmaintenance,radialenginesbecamethetypemostfavouredbydesignersofAmericanairtransports.TheCurtiss-WrightCorporation(formedfromthemergerofCurtissAeroplaneandMotorCompanyandWrightAeronauticalin1929)producedaseriesofWhirlwindandCycloneradialengines;Pratt&WhitneyAircraftlauncheditsWaspdesigns.ManyoftheseAmericanradialenginespoweredairplanesbuiltoverseas.Bytheendof

theseAmericanradialenginespoweredairplanesbuiltoverseas.Bytheendofthe1930s,innovationssuchasvariable-pitchpropellers,superchargers(toenhancehigh-altitudeengineperformance),andhigh-octanefuelshadcontributedtodramaticallyimprovedperformanceinbothliquid-cooledandair-cooledradialengines.

Duringthelate1920sandearly1930s,theU.S.PostalServiceinstitutedpaymentformulasthatfavouredaircraftlargeenoughtocarrypassengersaswellasmail.ArisingvolumeofresearchreportsfromtheNACAfacilitatedmanyimprovedaircraftdesigns.TheresultwasaswiftincreaseinlargerplaneswithimprovedradialenginesandashiftfrombiplanestotrimotormonoplanetransportsmarketedbyasubsidiaryofFordandbytheEuropeanbuilder,AnthonyFokker,whohadsetupshopintheUnitedStates.

Largelyowingtoairlinerivalry,AmericantechnologyhadalreadytakenamajorstepforwardwiththeintroductionoftheBoeingCompanyModel247airliner,whichcruisedatabout180miles(290km)perhourandenteredservicewithUnitedAirlines,Inc.,in1933.Withitsall-metalstressed-skinconstruction(whichusedthemetalskincoveringitselftocarryaerodynamicloads),retractablegear,two550-horsepowerPratt&WhitneyWaspradialengines,andcowlingsinspiredbyNACAresearch,the10-passengerModel247seemedtobehead-and-shouldersabovecompetitiveaircraft.

Shortlybeforethe247beganflying,aFokkertrimotorofTranscontinental&WesternAir,Inc.(TWA),crashedinaKansasfarmfield.Everybodyaboarddied,includingtheUniversityofNotreDame’sreveredfootballcoachKnuteRockne.Subsequentinvestigationofthecrashraisedquestionsaboutstructuralweaknessintheplane’smainwooden-wingspar.Controversyabout“woodenairplanes”andcriticismoftheFokkerplanegenerallygavetrimotorairlinersabadimage.WhenTWAaskedmanufacturerstosubmitdesignsforareplacement,DouglasAircraftCompany(laterMcDonnellDouglasCorporation)respondedwithanall-metaltwin-engineairliner.TheDC-2,withanadvancedNACAcowling,refinedstreamlining,andotherimprovements,mountedWrightCycloneenginesandcarried14passengers,surpassingtheBoeing247ineveryway.Significantly,leadingEuropeanairlinessuchasKLMacquiredthenewDouglastransport,beginningatrendforEuropeanoperatorstobuyAmericanequipment.Asubsequentmodel,thelegendaryDC-3,enteringservicein1936,mounted1,000-horsepowerCycloneorWrightWaspradialengines,cruisedat185miles(300km)perhour,andcarried21passengers—doublethecapacityoftheBoeing247.By1939,withsuperiorseatcapacity,performance,andancillaryrefinements,DC-3transportsalreadywerecarrying90percentoftheworld’s

airlinetraffic.

THEDC-3

TheDouglasAircraftCompany’sDC-3wasalowwing,twin-enginemonoplanewithretractablelandinggearthatinvariousconformationscouldseat21or28passengersorcarry6,000pounds(2,725kg)ofcargo.Itscruisingrangewas1,500–2,100miles(2,400–3,350km).Fromitsfirstappearancein1935,itdominatedtheinfantairlinebusiness.Inthemid-1940sallbut25ofthe300airlineplanesoperatingintheUnitedStateswereDC-3s.Incivilianservice,theplanewasoperatedbyatwo-mancrew,usuallywithacabinattendant.

Pilots,bothmilitaryandcivilian,lovedtheDC-3.Ittookoffeasily,cruisedcomfortablyat185miles(300km)perhourat10,000feet(3,000metres),andhadalowstallingspeedof67miles(107km)perhour.Pilotssaiditlandeditself,anditcouldflyononlyoneengine.Withstressedaluminumsheathing,itwasastrongplane.WhenproductionoftheDC-3endedin1945,morethan13,000ofthemhadbeenbuilt.ItisfrequentlysaidthatflyingwasacuriositywhentheDC-3wasfirstbuiltbutwasstandardtransportationwhenitceasedproduction.TheDC-3’seaseofhandlingandmaintenance,itsfacilityattakingoffandlandingonshortrunways,anditsremarkablereliabilitycombinedtokeepitflyinginmanypartsoftheworldintothe21stcentury.

TheDC-3’sWorldWarIIversion,designatedtheC-47,wassimpleandeffective.Itwasusedtotransportpassengers(28),fullyarmedparatroopers(28),woundedtroops(18stretchersandamedicalcrewofthree),militarycargo(e.g.,twolighttrucks),andanythingelsethatcouldfitthroughitscargodoorsandweighednotmuchmorethanthreetons.Theairplanewasalsousedtotowglidersandwasevenconvertedtoanefficient,high-speedgliderbysimplyremovingitsengines(andfairingovertheiremptycowls)andothernonessentialweight.

WhiletheDouglastransportsdramaticallyimprovedairtravelwithintheUnitedStatesandalongEuropeanroutes,airlineentrepreneurskeptlookingforavehiclefortransoceanictravel.Manyinthe1930sstillbelievedthathugegas-filledairshipswouldbethekey.Germanybuiltdiesel-poweredhydrogen-filled

airships,ordirigibles,suchastheHindenburg,whichflewNorthAtlanticschedulesbetweenEuropeandtheUnitedStatesduringthesummermonths.AmericanAirlines,Inc.,publicizedspecialschedulesthatallowedDC-3passengerstomaketransatlanticconnectionswiththeHindenburg’sterminusinNewJersey.Thisshort-livedarrangementendedwiththeHindenburg’stragicandfierydestructionuponitsarrivalfromEuropetoopenthe1937travelseason.Plansforutilizingdirigiblesaspassengerlinersquicklyfaded.

Thatleftflyingboats.PanAmericanWorldAirways,Inc.(PanAm),purchasedanumberofdesignsfromtheRussian-bornAmericanengineerIgorSikorsky.PanAmoperatedthemonoverwaterroutesintheCaribbeanregion,oftensavingweeksoftraveltimewhencomparedwithsteamshipandrailwayconnections.Bythelate1930s,AmericanmanufacturerssuchastheMartinCompany(nowtheMartinMariettaCorporation),Sikorsky,andBoeingwereallproducingverylargefour-engineflyingboatsintendedforserviceovertheAtlanticandPacific.In1935,usingislandsstrungacrossthePacific,PanAmcompletedinstallationofstopoverpassengerfacilitiesanditsownradiocommunicationsandmeteorologicalnetwork.WithMartinflyingboats,mostflightscarriedmail,alongwithoccasionalgovernmentorbusinesspassengerswhocouldpaythehighfares.

Inauguraldeparturesoccasionedconsiderablefanfare.In1939EleanorRoosevelt,wifeofU.S.PresidentFranklinD.Roosevelt,smashedabottleofchampagneoverthebowofanimposingYankeeClipperflyingboattolaunchscheduledairmailandluxurypassengerserviceacrosstheAtlantictoEurope.Thesepromising,ifexpensive,travelinnovationsweresooncurtailedbywartimeconditionsinAsiaandEurope.Inanycase,progressinlong-rangeland-basedfour-engineairlinersrepresentedadvancedengineeringthatwouldhavesoondisplacedflyingboats.

EleanorRooseveltchristensthePanAmericanflyingboatYankeeClipperatAnacostaNavalStationin1939.ThomasD.McAvoy/Time&LifePictures/GettyImages

Fortuitously,thewidespreadboundariesoftheUnitedStatescontainedagrowingnumberofurbancomplexeswithinterveningdistancesthatmadeairlineserviceadesirableoption.Americantransportdesignstendedtofavourmorespeedfortime-consciouspassengers.Incomparison,airwayswithinthecloserboundariesofwesternEuropefavouredshort-haulservice,oftentradingspeedforluxury,evenonlongercolonialrouteswherestatesubsidiesdeflectedtechnologicalcompetition.

Boeing’sStratoliner,apathbreakingtransportthatfeaturedapressurizedcabin,enteredservicein1940.Pressurizationenabledairlinerstoflyaboveadverseweather,permittingtransportstomaintaindependableschedulesandgivingpassengersamorecomfortabletrip.Moreover,athigheraltitudes,

givingpassengersamorecomfortabletrip.Moreover,athigheraltitudes,airlinersactuallyexperiencedlessatmosphericfriction,ordrag,enhancingtheirperformanceandfuelefficiency.OnlyafewStratolinersenteredservicebeforeWorldWarIIledBoeingtofocusonbuildingbombers.

Meanwhile,DouglashadintroducedtheDC-4.Althoughitwasunpressurized,itpossessedacomparableperformancetotheStratolinerandcouldcarrymorepassengers.Also,theDC-4hadatricyclelandinggear(unliketheStratoliner’sconventionaltailwheel),whichfacilitatedboardingofpassengers,improvedthepilots’viewoftherunwayandsurroundingairportenvironment,andenhancedtheplane’stakeoffcharacteristics.TheDC-4achievedproductionstatus(astheC-54)duringthewarastheU.S.ArmyAirForces’principallong-rangetransport.Lateintheconflict,itwasjoinedbytheLockheedL-049Constellation(instantlyidentifiablebyitstripleverticalfins),originallydesignedin1939asacommercialairlinerthatblendedapressurizedfuselage,tricyclelandinggear,andotherstate-of-the-artfeatures.CharacteristicsofthesesophisticatedcivilianplanesgavetheUnitedStatesamajoradvantageinpostwarairlinercompetition.

THEAERONAUTICALINFRASTRUCTURE

Theimpressivedevelopmentofairlinesandscheduledairtravelrestedheavilyontheevolutionofanaeronauticalinfrastructure.Withrootsinthelate19thcentury,Europeanlaboratoriessetthepaceintheoreticalaeronauticalresearch,buttheNACA,establishedin1915,soonevolvedasoneoftheworld’sleadingaeronauticalcentres.Thecreationofspecializedorganizationstoinvestigateaccidents,determinetheprobablecause,andmakerecommendationstoavoidrepetitionplayedakeyroleintheimprovementofsafeairtravel.

IntheUnitedStates,theDanielGuggenheimFundforthePromotionofAeronautics,aprivateorganization,spearheadedamilestoneexperimentin1928inwhichthepilot’sresponsestoacombinationofelectronicsignalsandairplaneinstrumentspermittedthefirstsuccessful“blindflight.”Thistechniquerepresentedahugestepforwardforaviation.Itmeantthatairlinescouldsustainschedulesthatrequiredflyingatnight.Italsomeantthatplanescouldflyinmanyweatherconditionsthathadpreviouslyforcedpilotstostaygroundedormakeunscheduledlandings.Moreover,theGuggenheimFundacceleratedthescienceofmeteorologyforweatherforecasting,codificationofaeronauticallaw,andtheestablishmentofcollege-levelaeronauticalengineeringdepartments(aswellasuniversityresearchlaboratories)thateducatedessentialcadresof

aeronauticalengineersandscientists.Bytheendofthe1920s,mostmajorcitiesintheUnitedStateshad

establishedmunicipalairports.Duringthedepressiondecadethatfollowed,variousNewDealgovernmentconstructionprogramsimprovedandbuiltadditionalairfieldswithpavedall-weatherrunways.Underfederalguidance,majorairfieldsalsoacquiredcontroltowersandradioequipmentaspartofanairtrafficcontrolsystemmeanttoensuresafeaircraftmovementswithinanincreasinglybusyairspace.Withabureaucraticframeworkandessentialflighttechnologies,abasicaeronauticalinfrastructurehademerged.Thestagewassetfortheintroductionoftrulymodernairlinersandtheirindelibleimpactonpassengertravel.

WARTIMELEGACIES

In1937Japanbeganfull-scaleoffensivesagainstChina.Europeanhostilitiescommencedin1939,andtheUnitedStatesbecameinvolvedinWorldWarIIin1941.InEurope,neutralcountriessuchasSweden,Switzerland,Portugal,andSpainhostedinternationalroutesonalimitedbasis,butthevagariesofwarvirtuallyendedregularlyscheduledflightsuntiltheendoftheconflictin1945.TheUnitedStatessuppliedthemajorityofairtransportsforAlliedforces.Thereasonsforthiswerequitestraightforward:TheDC-3hadalreadydemonstrateditsvirtuosity,thesuperiorDC-4wasenteringservice,andthecountry’sprodigiousproductioncapabilitycouldsatisfymostrequirements.Draftedintomilitaryservice,theC-47(DC-3)andthefour-engineC-54(DC-4)becametheworkhorsesfortheU.S.,BritainanditsCommonwealth,andair-transportunitsofEuropeangovernments-in-exile.

Asaharbingerofthingstocome,thewartimeachievementsoftheU.S.ArmyAirForceAirTransportCommand(ATC)constitutedamajorstepforward.TheATCbecamelegendaryduringitstransportservicesacrossthetoweringHimalayanmountainranges(pilotscalledthesechallengingmissions“flyingthehump”),carryingcrucialsuppliestoChineseandAlliedforcesintheChina-Burma-Indiatheatre.Moreimportant,theATCoperatedaglobalnetwork,establishingairfields,communicationcentres,andweather-forecastingfacilitiesthatpioneeredasustainedsystemofairtransportationonanintercontinentalbasis.Thetimerequiredtoreachdestinationsaroundtheworldcontracteddramatically,fromajourneyofweekstoonlyafewdays,or,withinmostcombattheatres,toafewhours.Transoceanictravelbecameamatterofroutine;atitspeakofoperations,ATCplanescrossedtheAtlanticatanaveragerateofoneevery13minutes.

oneevery13minutes.Anticipatingtheimpactofpostwarairlines,manyknowledgeableauthorities

advocatedworldwideprotocolstonormalizeflyingproceduresandlegalissuessoastopromoteanorderlyimplementationofforeignandintercontinentalairroutes.In1944,duringahistoricmeetingconvenedinChicago,internationalrepresentativeseventuallyagreedonaprovisionaladministrativeentity.By1947,thefull-fledgedInternationalCivilAviationOrganization(ICAO)hadsettledinMontrealasanadjunctofthenewUnitedNationsorganization.TheICAOspecifiedEnglishastheuniversallanguageforpilotsandairtrafficcontrollersengagedininternationaloperations.Additionalprotocolsspecifiedstandardizedformatsforterminology,radiofrequencies,navigationalequipment,emergencyprocedures,runwaymarkings,andairportlighting.Withouttheseprotocols,globalairtravelwouldhaveexperiencedachaotic—andunacceptablydangerous—evolution.

POSTWARAIRLINES

Afterthewar,manyairlineslookedforanupdatedDC-3replacementtouseonshort-to-intermediateflights.TheBritishbuilt163copiesoftheportlytwin-engineVickersViking,anunpressurizedtransportwith24to27seats(latermodifiedtocarry34to38passengers)thatcruisedamiablyat320km(200miles)perhouroverEuropeanroutesandthoseofmanyCommonwealthcountries.However,neitherBritish,French,Italian,norotherEuropeanmanufacturersenjoyedmuchsuccessagainstAmericandesigns.Forexample,ConsolidatedVulteeAircraftCorporation,morecommonlyknownasConvair,builtthespeedytwin-engine240/340/440series,withtrendytricyclelandinggear,whichsoldmorethan1,000modelsbetween1947and1956,plusseveralhundredmilitaryversionsthatoftentrickledbackintocivilservice.Convairshadamaximumcruisingspeedof280miles(450km)perhour,andtheirpressurizedcabinsprovidedunaccustomedcomfortfor40to50passengers(dependingonthemodel)insmallerairlinemarketsaroundtheworld.Subsequentturbopropconversionskeptthetypeinserviceforseveraldecades.

Duringthisperiod,theSovietUnionconsideredbothpracticalityandpoliticsforitsextensiveAeroflotinternalnetwork.Inthelate1930s,thecountryhadacquiredastate-of-the-arttransportbysigningalicenseagreementtobuildtheDouglasDC-3,equippedwithSovietengines.Althoughnumerousexamplescontinuedtoserveinthepostwaryears,theywereeventuallysucceededbytheIlyushinIl-12,atrimunpressurizedtwin-enginetransportthatalsofeatured

retractabletricyclelandinggear.Alargermodel,theIl-14,wentintooperationduringthe1950s.Consideredslowandtechnologicallyunsophisticatedbymodernstandards,theseplanesplayedanideologicalroleintheColdWarbyparryingWesternimports.Productiontookplaceincommunist-bloccountries;theIl-12andIl-14seriesnumberedintothethousands,servingasmilitarytransportsaswellasthebackboneforAeroflotoperationsandcivildutiesineasternEurope.TheyoperatedinChinaandweresuppliedtogovernmentsinAfricaandAsia,wheretheSovietswishedtoexpandtheirinfluence.

TheIl-12andIl-14transportshadcruisingspeedsofabout320km(200miles)perhourandcouldcarry27to32passengersoverroutesofupto480km(300miles).AcrossthelengthandbreadthoftheSovietUnion,thisseeminglymodestperformanceservedquitewell.Everyregionofthecountryincludedcitiesandtownsthatoftenlackedbothrailservicesandthebenefitsofall-weatherroads.Riversoftenofferedagoodalternativetransportroute,butlongRussianwintersandgenerallychallengingconditionsusuallymeantthattheywerefrozensolidorcharacterizedbyseasonalfloodsandshiftingnavigationalchannels.Consequently,theschedulesofAeroflot—withitssubsidizedbargain-basementfares—constitutedtheonlyreasonablyreliabletransportandcommunicationlinksthroughouttheyear.Largelong-rangetransportsfulfilledtheimmediate—andcrucial—needfortimely,practicaltravelarrangementsthatboundthousandsoflargeandsmallpopulationcentrestoeachotherandtonationalpassengernetworks.ThesturdyIl-12andIl-14transportscouldstillbeseenatairportsthroughthe1980s.

After1945,DouglasintroduceditspressurizedDC-6tomatchtheLockheedConstellationondomesticandinternationalroutes.Astheyenergeticallycourtedsalestorivalforeignairlines,Americanmanufacturersconstantlyengagedinback-and-forthconteststoimprovetheirproducts.SincetheNorthAmericanmarketforairlinersgeneratedhigh-volumeproduction,unitcostsremainedlow,andtheybecamehighlycompetitivewhenpricedagainstEuropeantransports.Eventually,theperformance,quality,andvalueofpostwarAmericandesignsledtotheirdominatingpresenceintheairlinefleetsofmajorcarriersoverseas.Hopingtocapturemarketshare,BoeingutilizedmajorcomponentsfromtheB-29bomberandtheC-97cargo/tankeraircraftinbuildingtheStratocruiser,aplanethatofferedunmatchedluxuryforairtravelersinthelate1940sandearly’50s.Itsfamouslyspaciouscabinseated55passengers,anditsbar/lounge,enteredthroughaspiralstaircasetothelowerdeck,createdasensation.PanAmandBritishOverseasAirwaysCorporation(BOAC)quicklyintroducedStratocruisersonpremierroutesacrosstheNorthAtlantic.However,eventhe

Stratocruiserfadedagainstbetter,fasterpiston-engineairlinersfromDouglasandLockheed.

ButtranscontinentalschedulesintheUnitedStatesinvariablyincludedastopforfuelenroute;transatlanticflightsbetweenNewYorkandEuropeusuallyrequiredrefuelinginNewfoundland,Iceland,orIreland.Theseconstraintsbegantoevaporateinthe1950swiththeLockheedSuperConstellationandtheDouglasDC-7.Theultimateversionsappearedin1956–57astheDC-7C,knownasthe“SevenSeas,”whichwascapableofnonstoptransatlanticflightsineitherdirection,andtheLockheed1649AStarliner,whichcouldflynonstoponpolarroutesfromLosAngelestoEurope.TheStarlinercarried75passengersatspeedsof350to400miles(560to640km)perhour.EachofitsWrightturbocompoundradialenginesdeveloped3,400horsepower.Priortotheintroductionofjettransports,thesestalwartaircrafttransformedthedynamicsofairtravelandcontinuedinservicewithmajorairlinesintothelate1960s.

Travelremainedastylishexperience.Mendonnedcoatsandties,andladiesappearedinhatsanddresses.Airportsfeaturedfirst-classrestaurantswhileairlinecabinservicefeaturedcrystalstemwareandqualitychina.Untilthe1950s,airlinepatronscharacteristicallytraveledonafirst-classbasis,andfaresremainedrelativelyhighuntilincreasedpatronagepavedthewayfordecreasedprices.Asearlyas1953,domesticairlinesintheUnitedStatesreportedmorepassengermilesthanrailroadPullmantravel.Beforetheendoftheyear,statisticsrevealedthatairlineshadalsotakentheleadastheprimemoverforAmericantravelersmakingtripsofmorethat200miles(320km).By1958themajorityofU.S.passengersheadedforEuropechosetogobyplaneratherthanbyoceanliner.Cabin-classseatsproliferatedonairliners,andfaresdroppedaccordingly.

Evenbeforetheadventofjetairliners,piston-enginetransportshadusurpedtraditionalrailwayandsteamshiptechnologyastheprincipalmodeoftransportforlong-distancetrips.Domestically,convenientairlinetimetablesenabledprofessionalandcollegiatesportsteamstoplaytightlyscheduledgamesonanationwidebasis.AirlinebusinesstravelintheUnitedStatesandoverseasexploded.Piston-engineairlinersmadeweekendskitripsandforeignexcursionspossibleforthousandsofmiddle-incomeindividualswhocouldfinallyfita10-dayEuropeanholidayintothetimeframeandbudgetoftheirannualvacation.AssociologistMaxLernerobserved,postwarairwaysledtothedemocratizationofAmerican—andglobal—travel.

GENERALAVIATION

FollowingWorldWarI,anumberofadventurouspilotsbeganusingairplanesfor“utilityaviation”—commercialphotography,surveying,lawenforcement,agriculturalpurposessuchasseedingandcropdusting,andmyriadotheractivities.IntheUnitedStates,hugenumbersofwar-surplusenginesandtrainingaircraft,aswellaslargerplanessuchastheDH-4,offeredacheapandeasywaytoentertheflyingbusiness.Althoughbarnstormersandacrobaticfliersalltoooftentarnishedtheimageofaviationbyperformingfoolhardystuntsinworn-outmilitarycastoffs,thephenomenonofutilityaviationattractedincreasingnumbersofusers.Bythelate1920s,asthesupplyofwarsurplusaircraftandenginesdriedup,newcompaniesbegantoofferimprovedenginesandplanes,includingaircraftwithenclosedcabinsthatcouldseattwotofivepeople,bringinganendtoopencockpits,helmets,goggles,andconsiderableenginenoise.

Throughoutthe1930s,despitetheGreatDepression,improvementscontinued,andthepracticeofusingpersonalaircrafttoconductbusinessbecamearecognizedaspectofmoderncommerce,especiallyasAmericanindustrycontinueditspatternofgeographicdiversityandscattereddivisions.Inordertosavetimeandexpensivepersonnelcosts,businessaviationprovidedthemeanstodeliverkeypeopletolocationswhereairlinesdidnotflyandroadorrailtravelwasindirectandtime-consuming.Amongthemostpopularprivateaircraftmodelswerethetwo-seatPiperCub,poweredbya65-horsepowerenginethatenabledacruisingspeedofabout85miles(140km)perhour;thefour-seatCessnaAirmaster,poweredbya145–165-horsepowerenginethatenabledacruisingspeedofabout160miles(260km)perhour;andtheseventoninepassengerBeechcraftModel18,poweredbytwo450-horsepowerenginesthatenabledacruisingspeedofabout220miles(350km)perhour.CessnaandBeechcraftstillusedradial-pistonengines,butPiperreliedonahorizontallyopposedfour-cylinderenginethatallowedengineerstodesignamorestreamlinedenginenacelle.Thistypeofenginebecamethepreferredstyleformodernlight-planedesigns.

TheCessnaAircraftCompanyproducedsome180Airmastersbetween1934and1941.Theplaneswereespeciallypopularforuseinaerialphotographybecauseoftheirgreatstabilityinflight.EncyclopædiaBritannica,Inc.

OtherdevelopmentsincludedIgorSikorsky’sworkonpracticalpiston-enginehelicopters.Technologicalprecedentsinthe1930sincludedtheautogiro,whichusedanunpoweredrotorforliftandapistonenginewithpropellerforforwardflight,buttheycouldnotmatchthehelicopter’sabilityforverticalflightandhovering.Postwareffortstoflyhelicoptersasshort-haulpassengertransportsfoundered,althoughtheybecameinvaluableinspecializedmissions(medevac,policepatrol,trafficmonitoring)andinsundryutilityroles.However,comparedwithfixed-wingaircraft,theirnumbersremainedsmall.

AfterWorldWarII,theacceleratingdemandforpersonalandutilityaircraftgaverisetothetermgeneralaviationtodescribeallflyingthatdidnotfallintothecategoryofmilitaryorscheduledairtransport.ManufacturerssuchasPiper,Cessna,andBeechcraftrepresentedanexpanding“lightplaneindustry,”althoughthegeneralaviationsectorincludedahostofmodifiedaircraftthatrangedfromwarsurplustwin-engineDouglasA-26bombers(rebuiltwithluxurypassengercabinsasfast,corporatetransports)tofour-engineDC-4transports(reequippedwithbiginternalfuselagetankstodumpretardantsonforestfires).

Forthelightplanebuilders,enginemanufacturerssuchasLycoming,Continental,andothersperfectedefficienthorizontallyopposedpistonenginesthatproducedfrom65tomorethan200horsepower;massproductionmadethemdominantininternationalapplications;severalappearedasturbo-superchargeddesignsdeliveringmorethan300horsepower.

Variousenginespoweredabewilderingvarietyofpostwarlightplanes,althoughPiper,Cessna,andBeechcraftledthemarket.Throughthe1950s,PiperandCessnamarketedhigh-wingmonoplaneswithtwotofourseats,suitableforshort-rangepersonalbusinessflying.Beechcraftintroducedthestylishall-metalV-tailedBonanza,withretractablelandinggear,higherspeed,andaroomyfour-placecabin.Manufacturersinstalledanewgenerationofcompactlightweightradiocommunicationandnavigationalequipment(eventuallydubbedavionics)thatimprovedoptionstoflyduringbadweather.Eventually,allthreemanufacturersproducedtwin-engineaircraft,aimedatbusinesstravel,thatcouldcarryfourtosixpeopleinmorecomfortatfasterspeeds.Thesedesignseventuallyprogressedinto“cabin-class”corporatetransportswithsuperchargedengines,flownbyapilotandcopilot,luxuryaccommodationsforfourtoeightpassengersinapressurizedcabin,alavatory,andadoorwithabuilt-instairway.

AlthoughaircraftproducedintheUnitedStatesdominatedtheworldwidegeneralaviationfleet,designsfromothercountriesalsowonasignificantmarketandbecameessentialcogsintheeconomiesofnumerousglobalregions.Canada,withalonghistoryofaircraftusedinwildernessflying,producedaruggedexampleknownastheBeaver,builtbyDeHavilland’sCanadianfirm.Withabigradialengineof450horsepower(ormore),thehigh-wingBeavercouldcarrysixtosevenpeople(oftenmore),orabout770kg(1,700pounds)ofpayload(usuallymore).TheBeaver’smoderatesizeallowedpilotstomaneuvertheplaneinandoutofprimitiveabbreviatedairstrips.Fittedwitheitherfloatsorskis,dependingonthelocaleandseason,BeaverscouldreachvirtuallyanypointinCanada’swildernessofforests,lakes,andArcticterrain.DeHavillandbuilt1,692oftheseremarkablyadaptableaircraft,andtheyservedin63countries,rangingfromtropicalclimestopolarregions.

TheSovietUnionproducedanaircraftofsimilarversatility,theAntonovAN-2.Withits1,000-horsepowerradialengine,theAN-2possessedacapaciousbarrel-likefuselagethatcouldaccommodateadozenorsopassengersor1,800kg(4,000pounds)ofcargo.Introducedin1947,itfeaturedabiplaneconfiguration,anditslargewingareagaveitexcellentflyingcharacteristicsforlow-levelagriculturalapplications—itsprincipalintendedfunction.ButtheAN-2’sabilitytooperatefromtheisolatedandruggedairstripsthatdottedtheSovietUnionmadeitaclassicall-purposeairplane.Inmanyremoteareassuchas

Unionmadeitaclassicall-purposeairplane.InmanyremoteareassuchasSiberia,theAN-2flewAeroflot’scoloursasalocalandshort-haulpassengertransportaswellascargohaulerandairambulance.Withmorethan5,000producedinUkrainebythelate1950s,followedbyapproximately11,900inPolandduringthe1960s,theAN-2notonlyservedthroughouttheSovietblocbutalsoappearedinAfrica,LatinAmerica,andAsia.WithintheSovietbloc,Poland,Romania,andCzechoslovakiabuiltavarietyofothergeneralaviationtypes,includingagriculturalmodels.

InGreatBritain,BeagleAircraft,Ltd.,enjoyedsomesuccessinthe1960s.ThedistinctivenamerepresentedanacronymderivedfromBritishExecutiveandGeneralAviationLimited.Althoughseveraldozenairplanesenteredservice,theycouldnotcompetewiththeirwell-equippedcounterpartsfromAmericanmanufacturers,whoseproductswerebackedbyefficientinternationaldealernetworks.Othercompaniesthatproducedplanesforcorporateuseandsmall“feeder”airlinesfaredbetter.Thetwin-engineDeHavilland(later,HawkerSiddeley)Dovearrivedin1945asalowwingdesignwithretractablegearandacapacityforIIpassengers.Itremainedinproductionthroughthe1960s,with554Dovesbuilt,including200formilitaryoperators.ThesecondaircraftwastheBritten-NormanIslander,withheadquarterslocatedontheIsleofWight.Designedasanup-to-datereplacementforobsoletetypessuchastheDove,thetwin-engineIslanderdebutedinthemid-1960s.Alongwithmodernavionics,itfeaturedahighwingandfixedgear,anditsmetalconstructionfollowedsimple,easilyfabricatedlineswithseatsforninepassengers,keepingitscosttoaboutone-thirdthatoftheDoveandsimilarplanes.TheIslandersoldwell,althoughitsproductionsitestendedtohopscotcharoundtheworld,includingfabricationsitesinRomaniaaswellasthePhilippines.Furthermodificationstotheoriginaldesigninvolvedaremarkablestretchofthefuselagetoaccommodatethepilotandonepassengerontheflightdeckand16passengersinthemaincabinandaredesignedwingandtailassembly.Withitshighlydistinctivethirdpistonenginemountedatoptheverticaltailrudder,itbecametheTri-Islander.Stillflyinginthe21stcentury,thevariousIslandersservedeffectivelyinmanythinlypopulatedareashavinggeographicalconstraints,suchastheCaribbean,andcarriedthousandsofpassengersthereandelsewherearoundtheworld.

TheFrenchwerealsobusyproducinglightplanestocompetewithAmericanproducts.AsinBritain,dozensoftypescameandwentduringthepostwardecades.Amongthosewithstayingpower,factory-builtaircraftdesignedforsaleinkitformenjoyedlivelysales,althoughmanyofthemremainedpartiallycompletedandmolderingawayinbasements,garages,andbarns.In1966an

extensiverealignmentofFrenchmanufacturersledtotheformationofSociétédeConstructiond’AvionsdeTourismeetd’Affaires,orSocata.ThenewcompanycontinuedtobuildtheprovenRallye,atrimtwo-passengermonoplane,butachievednotablesuccesswithitsownrangeoflarger,morepowerfulsingle-enginebusinessplaneswithretractablegear.Bythe1990s,theperformanceandreliabilityoftheSocataTobagoandTrinidadserieshadmadethemseriouscompetitorsintheNorthAmericanmarket.

Throughthe1960s,piston-engineairlinersstillplayedamajorroleinairtravel,andtheirubiquitouscounterpartsingeneralaviationenlivenedtheaeronauticalscene.In1969commercialairlinescountedabout2,500transports;122,500aircraftrepresentedthegeneralaviationfleet.Thesubsequentimpactofgas-turbineenginestransformedbothcategories.Olderpiston-engineairlinersoftensoldieredonasfirefightingtankers,whilemanyothersshuttledpassengersandcargofromremoteairfieldstovariousdestinations.Myriadsofpiston-poweredlightplanescontinuetopopulatetheairwayseverywhere.Thegrandepochofpiston-engineaircraftmayhavewaned,buttheirstorycontinues.

CHAPTER5THEJETAGE

Fromtheveryinventionofflightatthebeginningofthe20thcentury,militaryaircraftandenginesgenerallyledtheway,andcommercialaviationfollowed.Atfirstthiswasalsothecaseinthejetage,whichbeganwiththeinventionofjetenginesundermilitarysponsorshipinthe1930sand’40s.Bythelate20thcentury,however,commercialjet-enginetechnologyhadcometorivalandsometimesevenleadmilitarytechnologyinseveralareasofenginedesign.And,althoughitwasnotimmediatelyevident,theinventionofthejetenginehadafarmoresignificantsocialeffectontheworldthroughcommercialaviationthanthroughitsmilitarycounterpart.Commercialjetaircrafthaverevolutionizedworldtravel,openingupeverycorneroftheworldnotjusttotheaffluentbuttotheordinarycitizensofmanycountries.

FIRSTEXPERIMENTS

JustasGeorgeCayleyandJohnStringfellowofEngland,LawrenceHargraveofAustralia,OttoLilienthalofGermany,andothershadconductedexperimentswithflightintheyearsprecedingWilburandOrvilleWright’ssuccessfulWrightflyerof1903,so,too,weretheremanypioneersinthefieldofturbineenginesbeforethealmostsimultaneousinventivesuccessesofFrankWhittleofEnglandandHansvonOhainofGermanyinthe1930sand’40s.

TheearlyexperimentersincludedtheinventorHeronofAlexandria(c.50

CE),withhissteam-poweredaeolipile.Inabout1500,LeonardodaVincicreatedasketchofachimneyjackthatusedhotgasesflowingupachimneytodrivefanlikebladesthatinturnrotatedaspit.Boththeaeolipileandthespitoperatedonprinciplesfirstexplainedin1687byIsaacNewton,whoselawsofmotionformedthebasisformodernpropulsiontheory.By1872GermanengineerFranzStolzehaddesignedthefirsttruegas-turbineengine.

IntheUnitedStates,SanfordA.Moss,anengineerwiththeGeneralElectricCo.,cameclosetoinventingajetenginein1918withhisturbosupercharger,whichusedhotgasesfromtheengineexhausttodriveaturbinethatinturndroveacentrifugalcompressortosuperchargetheengine.(TheinventionwasvitaltoAmericanairpowerduringWorldWarII.)Theprocesswascarriedastepfurtherin1920,whenAlanA.GriffithofEnglanddevelopedatheoryofturbinedesignbasedongasflowpastairfoilsratherthanthroughpassages.GriffithsubsequentlyworkedformanyyearsforRolls-Royce,Ltd.

WORLDWARII

Thejetenginewasunusualinthatitwasindependentlybroughttofruitionataboutthesametimeintwocountriesthatwouldsoonagainbeatwar.InGreatBritain,aRoyalAirForceofficer,FrankWhittle,inventedthegas-turbineenginethatwouldpowerthefirstBritishjet,theGlosterE.28/39,whichmadeitsfirstflightonMay15,1941.InGermany,HansJoachimPabstvonOhainworkedontheproblemofgas-turbineengineswithoutanyknowledgeofWhittle’sefforts.VonOhainfoundbackingfromtheaviationindustrialistErnstHeinkel,whosoughttohaveanengine-manufacturingcapabilitytocomplementhisaircraftcompany.Workproceededswiftly,andonAug.27,1939,vonOhain’sHeS.3BengineenabledErichWarsitztomaketheworld’sfirstsuccessfulturbojet-poweredflightinhistoryintheHeinkelHe178.

NotableAmericanexperimentersinjet-aviationtechnologyincludeNathanPriceofLockheedCorporation,whodesignedandbuilttheL-1000,andVladimirPavleckiandArtPhelanatNorthropAircraft,Inc.

Britain’sinitialsetbacksduringWorldWarIIspurredinterestindevelopingthejetengine,whileGermany’ssuccessesleditsleaderstoadecisiontodeferalltechnicaldevelopmentsinweaponrythatcouldnotberealizedwithinayear.Despitethis,theJunkersMotorenwerkeGmbHhadassignedAnselmFranztodevelopajetengine,beginningin1940.Junkersputhisengineintoproduction,anditpoweredthefirstoperationaljetfighterinhistory,theGermanMesserschmittMe262.

MesserschmittMe262.BritainandtheUnitedStatesalsointroducedjetfighters,withtheBritish

GlosterMeteormakingitsfirstflightonMarch5,1943.ThefirstAmericanjetfighter,theBellP-59A,lackedtheperformancenecessaryforcombat,sothefirstoperationalU.S.jetfighterwastheLockheedP-80A,whicharrivedtoolateforcombatinWorldWarII.ItwouldprovetobeinvaluableduringtheKoreanWarjustfiveyearslater,though.TheSovietUnionalsoconductedexperimentswithjetengines,includingtheinstallationoframjets,butthesewereonasmallscale.

TECHNICALADVANTAGESANDCHALLENGES

Whittle,vonOhain,andothersmetresistancetotheirideasbecauseconventionalthinkersbelievedthatthejetenginewouldproducetoolittlepowerandconsumetoomuchfueltobeeconomicallypractical.Itwasnotgenerallyrecognizedthatathigheraltitudesthejetwouldproducemorepowerwithacceptablefuelefficiency.Understandably,eventhemostdedicatedengineexpertsdidnotanticipatetherapidpaceatwhichjet-engineperformancewouldbeimproved.

Ithappenedthatthejetengineenteredthepropulsionsceneatatimewhenconventionalreciprocatingenginesandpropellerswerereachingtheirphysicallimits.Propellerswerealreadyencounteringsupersonictip-speedsthatdestroyedtheirefficiency,andengineshadgrownsocomplexthatadditionalhorsepowerinthe3,000–4,000rangedependedonalargenumberofcylindersandcomplexsuperchargingthatgeneratedproblemsinoperationandmaintenance.

Withtheircontinuousrotarymotion,jetenginesweremechanicallysimplerandsmootherthanreciprocatingpistonswiththeirroughpounding.Jetenginesdevelopedrapidlyandby1950hadreachedlevelsofpowerthatwereimpossiblewithpistonengines.Reciprocatingenginesforaircrafthadreachedapracticallimitwiththe3,500-horsepower,28-cylinderPratt&WhitneyR-4360engine,whilesomemodernjetengines,suchastheGeneralElectricGE90-115,canproduceasmuchas115,000poundsofthrust.TheR-4360enginespoweredthelastgenerationofpiston-poweredbombers—namely,theBoeingB-50,whichwasinfrontlineserviceforonlyafewyearsasabomberbeforebeingrelegatedtoa(jet-assisted)tankerrole.Incontrast,theBoeing777,whichusestheGE90-115engine,firstflewin2003andwilllikelyremaininservicefortwoormoredecades.Thrustandhorsepoweraredifficulttoequate,butonepoundofthrustisequivalenttoonehorsepowerat375miles(600km)perhour.

Itwasnotimmediatelyobviousthatthejetenginerequiredmajoradvances

Itwasnotimmediatelyobviousthatthejetenginerequiredmajoradvancesinairframedesignandsupportfacilities.First,airframesneededtobemuchlargertocarrytheadditionalpassengersrequiredtomakejetaircrafteconomicallysound.Theywouldalsohavetobemuchstrongertoaccommodatethepressurizedfuselageandthemanytransitionsbetweenlowaltitudesfortakeoffsandlandingsandhighaltitudesforcruising.Anotherstructuralchangewastosweepthewingsbacktoreducethedragincreaseassociatedwithapproachingsupersonicflight.ThiswasapossibilityfirstelucidatedbyGermanengineerAdolphBusemanin1935andafewyearslaterindependentlybyRobertT.JonesattheU.S.NationalAdvisoryCommitteeforAeronautics(NACA).Inaddition,aircraftandgroundinstrumentationbecamefarmoresophisticated.Groundhandlingequipmenttoservicetheaircraftalsowasvastlyimproved,aswasairportinfrastructureforrefueling,loading,andunloading.Navigationanden-routesurveillancewerealsomuchimprovedtohandletheinitialgrowthofjettrafficbutsubsequentlyhadtobeoverhauledagainwhenthenumberofflightsgrewtothepointofsaturatingairtrafficcontrolcapability.

THEBLACKBOX

Theblackbox,orflightrecorder,isaninstrumentthatrecordstheperformanceandconditionofanaircraftinflight.Governmentalregulatoryagenciesrequirethesedevicesoncommercialaircrafttomakepossibletheanalysisofcrashesorotherunusualoccurrences.Flightrecordersactuallyconsistoftwofunctionaldevices,theflightdatarecorder(FDR)andthecockpitvoicerecorder(CVR),thoughsometimesthesetwodevicesarepackagedtogetherinonecombinedunit.TheFDRrecordsmanyvariables,notonlybasicaircraftconditionssuchasairspeed,altitude,heading,verticalacceleration,andpitchbuthundredsofindividualinstrumentreadingsandinternalenvironmentalconditions.TheCVRrecordsverbalcommunicationbetweencrewmemberswithintheaircraft’scockpitaswellasvoicetransmissionsbyradio.Aircraftsoundsaudibleinthecockpitarealsocaughtontherecorder.Flightrecordersarecommonlycarriedinthetailoftheaircraft,whichisusuallythestructurethatissubjecttotheleastimpactintheeventofacrash.Inspiteofthepopularnameblackbox,flightrecordersarepaintedahighlyvisiblevermilioncolourknownas“internationalorange.”

Thevoiceandinstrumentdataprocessedbytheflightrecorderarestoredindigitalformatonsolid-statememoryboards.Uptotwohoursof

cockpitsoundand25hoursofflightdataarestored,newdatacontinuouslyreplacingtheold.Thememoryboardsarehousedwithinaboxorcylindercalledthecrash-survivablememoryunit.Thisistheonlytrulysurvivablecomponentoftheflightrecorder(theothercomponents,suchasthedataprocessor,arenotnecessaryforretrievalofdata).Consistingofaheavystainless-steelshellwrappedwithinlayersofinsulatingmaterialandcoveredbyanaluminumhousing,amemoryunitisexpectedtosurviveimpactsof3,400G’s,flametemperaturesashighas1,100°C(2,000°F),andpressuresencounteredat6,000metres(20,000feet)underwater.Intheeventofacrashatsea,flightrecordersareequippedwithasonardevicethatisdesignedtoemitanultrasoniclocatorsignalforatleast30days.

Flightrecordersofvaryinglevelsofsophisticationhavebeeninexistencealmostsincethebeginningofmannedflight.TheWrightbrothersaresaidtohaveinstalledadeviceontheirfirstflyerof1903thatloggedsuchparametersaspropellerrotationandairspeed,andCharlesLindbergh,inhisepoch-makingflightacrosstheAtlanticin1927,employedabarometricdevicethatsensedchangesinairpressure(andthereforealtitude)andrecordedthesechangesbytracinglinesonarotatingspool.

AscivilaviationdevelopedintheyearsbeforeWorldWarII,“crash-survivable”flightrecorderscametobeseenasavaluabletoolinanalyzingaviationdisastersandcontributingtothedesignofsaferaircraft.However,trulyserviceablerecordersthathadanychanceofsurvivingplanecrasheswerenotproduceduntilseveralyearsafterthewar.IntheUnitedStates,creditforthefirstsurvivableFDRisgiventoJamesJ.Ryan,anengineeremployedbyGeneralMillsintheearly1950s.Ryan’sVGAFlightRecordersensedchangesinvelocity(V),gravitationalforces(G),andaltitude(A)andinscribedthemeasurementsonaslowlymovingstripofaluminumfoil.Asreleasedin1953andsoldbyGeneralMillstotheLockheedAircraftCompany,theentireapparatuswasenclosedinayellow-paintedsphericalshell.Beginningin1958,largercivilianpassengeraircraftintheUnitedStateswererequiredtocarrysurvivableFDRs,andnumerousotherdeviceswereproducedemployingvariousrecordingmedia,frommetalstripsto,eventually,magnetictape.

Paralleldevelopmentsoccurredelsewhereintheworld.AseriesofdisastrouscrashesofDeHavillandCometjetlinersin1953–54spurredDavidWarren,ascientistatAustralia’sAeronauticalResearchLaboratory(ARL),todesignthefirstcombinedFDRandCVR.Therecording

mediumforWarren’sARLFlightMemoryUnitwassteelwireofthetypethenbeingusedinmagneticaudiorecorders.AfterademonstrationofthedeviceinBritainin1958,ajournalistissaidtohavegivenitthesobriquetblackbox(thecommonnameforallflightrecorderstothisday),thoughWarren’srecorder,asproducedcommerciallybyS.Davall&Sonbeginningin1960,washousedinanegg-shapedcasingthatwaspaintedred.Othertheoriesoftheoriginofthetermblackboxhavebeenoffered,includingthecharredappearanceofearlyflightrecordersretrievedfromafierycrash.

Duringthe1960s,crash-protectedFDRsandCVRsbecamemandatoryonairlinersaroundtheworld.Mostflightrecordersemployedmagnetictape,butduringthe1990sagreatadvancementcamewiththeadventofsolid-statememorydevices.Memoryboardsaremoresurvivablethanrecordingtape,andthedatastoredonthemcanberetrievedquicklybyacomputercarryingthepropersoftware.Acompletepicturecanbecreatedofconditionsontheaircraftduringtherecordedperiod,includingacomputer-animateddiagramoftheaircraft’spositionsandmovements.VerbalexchangesandcockpitsoundsretrievedfromCVRdataaretranscribedintodocumentsthataremadeavailabletoinvestigatorsalongwiththeactualrecordings.Thereleaseofthesematerialstothepublicisstrictlyregulated.

Itwasrecognizedalmostfromthestartthatthehigherconstructioncostofthejetairlinerwouldneedtobeamortizedthroughintensiveuse.Whatwasnotinitiallyknown,though,wasthegreaterlongevitythatjetairlinerswouldhavecomparedwiththeirpiston-enginepredecessors.Theimprovementinengineoperationhasbeenthemostspectacular,withjetenginesnowhavingintervalsbetweenoverhaulsthatrunintotensofthousandsofhoursandwithcorrosionandmoleculardecayratherthanwearbeingthebiggestmaintenanceproblem.

Whileadvancesinjetaviationhavebeenphenomenal,theindustryfacesgreaterrisksthaneverbefore.Thegrowthinperformancehasbeenmatchedbyagrowthincostandadiminutionofthenumberofaircraftrequiredbycivilandmilitarycustomers.Commercialairlinersaremorecosteffectivethaneverbeforeandlastlonger.Anddevelopmentofnewaircraftcostsbillionsofdollars,requiringacontinuedgrowthinpassengertraffictokeepproductionlevelssteadyorclimbing.

THEAIRLINESRE-EQUIP

InBritain,theproductionofadvancedcommercialaircrafthadbeenabandonedduringthewar,whilethegreatercapacityandefficiencyofAmericanindustryallowedthecreationofthelong-distancepiston-engineDouglasC-54(DC-4)andLockheedC-69Constellationaircraft.AcommitteeheadedbyaviationpioneerandformermemberofParliamentJohnMoore-Brabazonwasestablishedin1943todiscusspostwarprospectsofrevivingtheBritishair-transportindustry,andamongthesuggestionswasaspecificationforatransatlanticmailplane.DeHavillandbegandesignstudiesthatledtothefirstflightoftheD.H.106CometjetairlineronJuly27,1949.Britainhadstolenamarchontheworld,forthe36-seatCometcouldflyat800km(500miles)perhourforupto2,400km(1,500miles).

Boeing,Douglas,andLockheedwerestunned;thoughtheCometwasconsideredtoosmallandtooshort-rangedforAmericanairlineroutes,theycouldoffernojetcompetitor.Britain’sgreatleadwentdowninflames,however,whenseveralCometscrashed,whichledtoitswithdrawalfromservicein1954.Thelatercrasheswereultimatelyattributedtostructuralfailureofthepressurecabinbecauseofmetalfatigue.

BoeingmadeagreatadvancewithitsrevolutionaryB-47bomber,firstflownonDec.17,1947.Thesix-engine,swept-wingaircraftwaspurchasedinlargequantities(2,032)bytheU.S.AirForce.ThisgaveBoeingtheengineeringandfinancialbasistocreatetheModel367-80,aprototypeforboththelater707passengerplaneandtheKC-135tanker.AlthoughatremendousgambleforBoeing,whichformanyyearshadbeenalmostentirelyamilitarysupplier,the707wasacommercialsuccessafterenteringservicein1958.DouglasrespondedwithitssimilarlookingDC-8.Bothaircraftwerelarger(someconfigurationscouldcarrymorethan200passengers)andfaster(morethan600miles[1,000km]perhour)thanthemodifiedComet4thatbeganserviceontheNewYorktoLondonrouteonOct.4,1958.

BoeingandDouglasquicklydominatedthemarket,makingitdifficultforalaterentry,theCV-880,fromConsolidatedVulteeAircraftCorporation,morecommonlyknownasConvair,togainafoothold.Convairhadstressedspeedratherthanpassengercapacity,butthe880andtheimproved990thatfolloweditwerecommercialdisastersthatalmostforcedthecompanyoutofbusiness.

BritaintrieddesperatelytoregainitsfootingintheairlinermarketbutfoundthatitsCommonwealthroutestructuresrequiredspecializedaircraftdesignsthat

werenotcompetitivewiththeBoeingandDouglasproductsintheworldmarket.TheBritishhadtheirgreatestsuccesswithturbopropairliners,inwhichthepropulsivepowerofthejetengineswastransferredtoapropellerthroughagearbox.ThemostprominentofthesewastheVickersViscount,whichwasbuiltinlargernumbers(444)thananyotherBritishairliner.TheViscountcouldcarryfrom40to65passengersatacruisingspeedof570to590km(355to365miles)perhour,dependingonconfiguration.ItwasemployedmostextensivelybyBritishEuropeanAirways.OtherBritishjetairliners,suchastheBritishAircraftCorporation(BAC)One-Eleven,theVickersVC-10,andtheHawkerSiddeleyAviationTrident,wereproducedinrelativelysmallnumbersandwerenotoutstandingcommercialsuccessesbecauseofthesuperbproductionandmarketingofequivalentU.S.airliners.

Francesucceededwithitsfirsteffortatajetairliner,creatingtheSud-Est(laterAérospatiale)SE210Caravelle,amedium-rangeturbojetintendedprimarilyforthecontinentalEuropeanmarket.FirstflownonMay27,1955,theCaravelleachievedsalesof282aircraft,andaturbofan-poweredvariantwasusedfordomesticroutesbyairlinesintheunitedStates—amarketingcoupatthetime.TheCaravellewastheworld’sfirstairlinertohaverear-mountedengines,adesignfeaturethatwasadoptedforsomeusesbyallothermajormanufacturers.

JetairlinerswereagenuinerequirementfortheSovietUnionbecauseofitsvastexpanseofterritory,whichincluded10timezones.TheTupolevTu-104prototypemadeitsfirstflightonJune17,1955,only11monthsafterthefirstflightoftheBoeing367–80but30monthsbeforethefirstflightofaproduction707.TupolevhadleapedaheadbyusingthecomponentsoftheTu-16bomber,addingonlyanew55-seatpressurizedfuselage.TheTu-104servedwellandreliablyformanyyearsbutwouldnothavebeenconsideredforusebyWesternairlinesbecauseofitshighoperatingcosts.ItbeganadynastyofTupolevairlinersthatcontinuestothisday.

Tupolev’seffortswerecomplementedbythoseofIlyushin,whichhasproducedalongseriesofsuccessfulturbopropandjetairlinersthatinrecentyearshavebenefitedbyaccesstoWesternenginesandelectronicstechnology.AfterthecollapseoftheSovietUniononDec.25,1991,thegreatSovietairlineAeroflotwasbrokenup,andformersatellitecountriesbegantolooktotheWestforairlinersthatweremoreeconomicaltooperate.TheresultwasanimmensereductioninbothdevelopmentandproductionofRussianairlinersandanutterinabilitytocompetewithWesternairlinerbuilders.

PROGRESSINENGINESANDAIRFRAMES

Twostagesinthejetliner’sdevelopmentmarkedthe1960s.Thefirstwastheadoptionoftheturbofanengine.Theturbofangainseconomybyhavingmuchofitsthrustpassaroundtheenginecoreratherthanthroughit.Thesecondstagewasmarkedbytheintroductionofthewide-bodied,400-seatBoeing747in1969.Thislarge,swift,andlong-rangedaircraftcreatedatransportationrevolution.Whereasairtravelhadoncebeenconfinedtotheaffluent,itnowbecameamass-marketconveyanceasairlineticketpricesfellandairlinesbecamemoresophisticatedintheirpricingpractices.Asthetotalmarketgrew,smallerjetandturbopropairlinersweredevelopedforshorterroutes.

Boeinghadalreadydemonstrateditsmasteryofthetechniqueofcreatingaircrafttomeetnewdemandsbycreatingfirstthethree-engineT-tailed727in1963,followedbyasuccessionofaircraft(the737[1967],757[1982],767[1981],777[2003],and787[2007])thatweretailoredtotheneedsofspecificairlinesandroutes.(The737,withmorethan6,000sales,isthemostproducedjettransportinhistory.)Eachofthesemodelswasmodifiedandimprovedovertimetotakeadvantageoftechnicaldevelopments,and,asaresult,Boeinghadanexcellentportfolioofaircrafttoofferairlinecompanies.

Low-bypassturbofanwithafterburner.CopyrightEncyclopædiaBritannica,Inc.;renderingforthiseditionbyRosenEducationalServices

DuringtheperiodofBoeing’sexpansion,Douglasranintomanagementproblems,andwhileitsDC-9wasaspectacularsuccess,itcouldnotmatchBoeing’sproliferationofdesigns.DouglaswasacquiredbyMcDonnellAircraftCorporationin1967,formingMcDonnellDouglasCorporation,andtheMcDonnellDouglasDC-10wascreatedtomeetanestimatedmarketrequirementforabout750wide-bodiedaircraft.LockheedsoughttoenterthesamemarketwithitstechnologicallymoreadvancedL-1011TriStar.McDonnell

samemarketwithitstechnologicallymoreadvancedL-1011TriStar.McDonnellDouglassold446DC-10s,whileLockheedsold250TriStars,withbothcompanieslosingmassiveamountsofmoney.McDonnellDouglasbelatedlystruggledonwiththeMD-11,animprovedDC-10,whilecontinuingtheDC-9astheMD-80andMD-90series.WhenBoeingacquiredthefirmin1997,itappliedthedesignation717tooneversionofthetwin-enginejet.

Inspiteoftheintensenatureofthecompetitiontobuildjetairliners,anewentrantappearedintheearly1970sfollowingintenseindustrialandpoliticalnegotiations.AirbusIndustriewasco-ownedbyFrench,German,British,Spanish,Dutch,andBelgiumcompaniesandsubcontractedmanypartstostillothercountries.EstablishedinDecember1970tobuildtheAirbusA300wide-bodiedtwin,thecompanywasdiscountedatfirstashavinglittlechancetocompete.However,itsaircraftwerewidelyaccepted,andaseriesofdesignsfollowedthatestablishedafamilyofaircraftthatmatchedBoeing’sofferings—and,withtheintroductionoftheA380in2005,threatenedtoexceedthem.TheAirbusfamilymarchedsteadilyforwardinsize,number,andutilityuntilitconsistedofnofewerthan14differentseriesofaircraft.ComplaintsfromtheUnitedStatesthatAirbuswasbeingsubsidizedbythevariousEuropeangovernmentswascounteredbythechargethatAmericanmanufacturerswereineffectsubsidizedbytheirsaleofaircrafttotheU.S.militaryandbyNationalAeronauticsandSpaceAdministration(NASA)research.

Asthejetenginematured,itmovedsuccessivelytoothersegmentsoftheairlinemarketandthen,asturbo-shaftsandturboprops,respectively,intohelicoptersandbusinessaircraft.ThesuccessoftheViscountturbopropairlinerwasemulatedbyahostofothers.Relativelysmallairlines,usingtheseplanesforroutesconnectingsmallercities,becameassociatedwiththelargercarriersandoftenadoptedthesamename.Inthelate1990s,smallerjetswithroomfor50to90passengersbegantoreplacetheturboprops.Thistrendwaspartofadramaticmakeoverintheprofileandoperationsofairlines,especiallyinNorthAmerica.

Amongbusinessaircraft,smallerjetengines,withgoodfuel-consumptioncharacteristics,becameavailabletopowerexecutivejets.ThefirsttoappearincludedtheLockheedJetStarof1957,whichwassoonfollowedbytheNorthAmericanSabreliner.Theseaircraftwereeclipsedbytheappearancein1963oftheLearjet23.Thisfive-to-seven-passengerjethadatopspeedofabout560miles(900km)perhourandarangeof1,830miles(2,945km).Favouredbycelebrities,Learjetbecamealmostagenerictermforthemanyexecutivejetsthatfollowed.Poweredbyturbofans,theseincludedexcellentaircraftfromFrance

(Dassault),Israel(IAI),andtheUnitedKingdom(DeHavillandandHawkerSiddeley).

Executivejetshavebecomemorecommonsincethe1960s.EncyclopædiaBritannica,Inc.

Businesseshadusedaircraftsincetheearly1920s,andasubstantialfleetoftwinpiston-engineexecutiveaircraftexistedwhentheexecutivejetsarrived.Althoughcompanieswereloathtoadmitit,mostexecutivejetswereinitiallypurchasedasaperquisiteofthetopmanagement,usuallyforachiefexecutiveofficerwholikedtoflyandfoundtheexecutivejet’sperformancecomparabletothatofairliners.Intime,however,itwasrealizedthatexecutiveaircraftweretoolsinexactlythesamewaythatfactorymachinesorcomputersweretools,andtheyweresubsequentlypurchasedinfarlargernumbersonthatbasis.Thetopexecutivejets,includingtheBoeingBusinessJet(avariationofthe737),theBombardierGlobalExpress,theDassaultFalcon900,andtheGulfstream500/550,featuredintercontinentalrangeandhighsubsonicspeeds.

AIRFORCEONE

AnyaircraftoftheU.S.AirForcethatiscarryingthepresidentoftheUnitedStatesiscalledAirForceOne.Strictlyspeaking,AirForceOneistheradiocallsignadoptedbyanyAirForceplanewhilethepresidentisaboard.Incommonparlance,however,thecallsignhasbecomeidentifiedwithspecificaircraftreservedforusebythepresidentfortravelwithintheUnitedStatesorabroad.Since1991twosuchaircrafthavebeeninservice:identicalBoeing747-200Bjumbojetsbearingthetailnumbers28000and29000andtheAirForcedesignationVC-25A.

29000andtheAirForcedesignationVC-25A.EachofthecurrentAirForceOneaircraftisequippedwithclassified

securityanddefensesystems,includingmeasurestoprotectonboardelectronicsagainsttheelectromagneticpulseofanuclearexplosion.Atelecommunicationscentreislocatedintheupperlevel,andinthelowerlevelisacargoholdwithaself-containedbaggage-handlingsystem.Themiddlelevelcontainsaccommodationsforasmanyas70passengersinadditiontothecrewof26.Theseaccommodationsincludeseatingandworkareasformediarepresentatives,securitystaff,andotherpersonnel;acombinationconference-diningroom;anin-flightpharmacyandemergencymedicalequipment;andtwogalleysinwhichasmanyas100servingspermealcanbeprepared.Thepresidentialsuite,locatedinthequietforwardareaoftheplane,containsanoffice,abedroom,andalavatory.ThetwoAirForceOnejetshavearangeofalmost8,000miles(morethan12,000km)unrefueled,butwithin-flightrefuelingtheyarecapableofcirclingtheglobe.

AirForceOne,aBoeing747reservedforusebythepresidentoftheUnitedStates,flyingoverMountRushmore,SouthDakota.U.S.AirForce

ThefirstAmericanpresidenttoflywhileinofficewasFranklinD.Roosevelt,andallpresidentssinceRoosevelthavehadtheirownreservedaircraft.Atfirstthesewerepropeller-drivenplanes(usuallyadaptedfrommilitarytransports),butstartingwithPres.DwightD.Eisenhowerjetsenteredthepresidentialfleet.Accordingtopopularlore,thecallsignAirForceOnewasfirstinvokedbythepilotofoneofEisenhower’splanesduringaflighttoFlorida,whenhewasconcernedthatairtraffic

controllersmightconfusethepresidentialplane’scallsign,AirForce610,withasimilarcallsignofanearbycommercialairliner.In1962,duringtheadministrationofJohnF.Kennedy,thefirstjetspecificallybuiltforpresidentialusewasdelivered—aBoeing707,giventhetailnumber26000andtheofficialdesignationVC-137C.ThisjetwasdestinedtobecomeasymbolofthepowerandprestigeoftheU.S.presidencyandtocreateinthepublicimaginationtheveryideaofAirForceOne.IndustrialdesignerRaymondLoewycontributedadistinctiveblue-and-whitecolourschemetotheexterioraswellasalogothatfeaturedthetitle“UnitedStatesofAmerica”onthefuselage,theU.S.flagonthetail,andthepresidentialsealonbothsidesofthenose.ThisdesignhasbeencarriedovertoallsubsequentAirForceOneplanes.

InJune1963thenewjetcarriedKennedytoadividedBerlin,whereheissuedhisfamousdeclaration“IchbineinBerliner,”andinNovember1963ittransportedtheassassinatedpresidentbacktoWashingtonfromDallas.LyndonB.Johnsonwassworninaspresidentontheplane,anditcontinuedtoserveastheprimaryorbackupAirForceOneduringtheadministrationsofJohnson,RichardM.Nixon,GeraldR.Ford,JimmyCarter,RonaldReagan,andGeorgeH.W.Bush.In1972theplanewasjoinedbyasisteraircraft,giventhetailnumber27000;thiswastheplanethatflewNixonbacktoprivatelifeinCaliforniauponhissuddenresignationinAugust1974.BothplaneswentthroughseveralrefittingsbeforebeingreplacedfordutyasAirForceOnein1990–91bythecurrentpairof747s.Aircraft26000wasretiredfromthepresidentialfleetin1998atWright-PattersonAirForceBase,Dayton,Ohio,whereitisondisplayattheNationalMuseumoftheUnitedStatesAirForce,and27000wasretiredin2001andisnowondisplayattheRonaldW.ReaganPresidentialLibraryandMuseuminSimiValley,Calif.

ThecurrentAirForceOnejetsarebasedatAndrewsAirForceBaseinMaryland,nearWashington,D.C.,andareassignedtothe89thAirliftWingoftheAirForce’sAirMobilityCommand.Theyhaveservedpresidents,vicepresidents(atwhichtimetheyareknownasAirForceTwo),andotherdignitariesundertheadministrationsofGeorgeH.W.Bush,BillClinton,GeorgeW.Bush,andBarackObama.Thepairofjetsisslatedforreplacementbythreenewaircraftbetween2017and2021.

AVIONICS,PASSENGERSUPPORT,ANDSAFETY

Duringthejetage,avionics,acoinedtermmeaning“aviationelectronics,”hasseenarapidgrowthineveryaspect,includingnavigation,instrumentation,communication,safety,andlandingassistance.

Theadventofthecathode-rayoscilloscopeanditsapplicationtoaircraftspurredtheavionicsrevolution,whichhadbegunwithrelativelyprimitiveradios.Whiletheinitialusesofthecathode-raydisplaywereformilitarypurposes(detectingincomingenemyaircraft),itwassoonappliedtoin-flightnavigation,controllingaircraftinterminalareas,andlandingoperations.Theground-controlledapproach(GCA),inwhichagroundobservermonitorsthecourseanddescentangleofanaircraftviaradar,enablespilotstolandunderextremelyadverseweatherconditions.GCAwasusedextensivelybytheU.S.militaryduringthe1948BerlinblockadeandairliftandwasapprovedforU.S.civilairlineusein1949.Anotheravionicssystem,theinstrumentlandingsystem(ILS),usesonboardinstrumentstointerpretsignalssentfromgroundstations.AratherprimitiveILSwasintroducedin1929butbecametrulyusefulonlyafter1945.Asradarbecamemorepowerfulandavailableingreaterquantity,itbecameusefulformonitoringaircraftastheyprogressedalongtheirroutes.

Incommunications,radiosoperatinginveryhighfrequency(VHF)reappearedafterWorldWarIIandbecamestandardforcivilandcommercialaircraft,whilemilitaryaircraftadoptedultrahighfrequency(UHF).Theintroductionofsatellitecommunicationintheearly1960s,whileinitiallyexpensive,finallyofferedthepotentialtoachievereal-timesurveillanceofeveryairborneaircraftanywhereintheworld.Meanwhile,theuseofsatellitesfornavigationleapedforwardinthemid-1990s,inpartbecauseitsadoptionwaslessexpensivethansatellitecommunicationsandinpartbecauseofitspinpointaccuracy.Globalpositioningsystem(GPS)satellitescanbeexpectedtoeventuallybeusedforterminalcontrolandlandingapproaches.

Thecathode-raydisplayalsofounditswayintothecockpit,whereitreplacedstandardanaloginformationpresentationsandmadefarmoreinformationinstantlyavailabletopilots.Whenintegratedintoautomaticpilots,thesedisplaysmakecockpitresourcemanagementakeyelementofflyingsafety.Therewerealmost-continuousexperimentswiththecathode-raytubefromthemid-1970s,butitwassupplantedbythecomputer-basedelectronicdisplayinthe1980s.Thefirsttrue“glasscockpit”wasfoundintheBoeing767(1981).Sincethattime,electronicdisplayshaveprogressedthroughoutaviationandmaynowbefoundeveninlightaircraft.Thenextgenerationincockpit

managementistheMultifunctionElectronicDisplaySubsystem(MEDS),whichallowspilotstocallupdesiredinformationonaliquidcrystaldisplay(LCD).Besidesbeingmoreeasilyunderstoodbyacomputer-literategenerationofpilots,MEDSislessexpensivetomaintainandmoreeasilyupdatedthanconventionalinstrumentation.

Intheareaofpassengersupport,thejetageexcelledintheticketingprocessandinthecreationoflargeterminals,butintheviewofmanyexperiencedtravelersitregressedintheareaofonboardcomfort.Seatingbecamemorerestricted,andtherapidretrievalofbaggageseemedtoremainanunsolvableproblem.Tosomeextent,onboardelectronicscompensatedfortheseinconveniencesbyprovidingamenitiessuchastelephones,television,andtheInternet.Mosttravelers,however,wouldsettleforalittlemorehipandlegroom.Safetyisoneareainwhichtherehasbeencontinualprogress,withmilitaryandcommercialaviationhavingvastlyimprovedtheirsafetyrecordsbyanymeasure.

SUPERSONICFLIGHT

Supersonicflightispassagethroughtheairatspeedgreaterthanthelocalvelocityofsound.Thespeedofsound(Mach1)varieswithatmosphericpressureandtemperature:inairatatemperatureof15°C(59°F)andsea-levelpressure,soundtravelsatabout1,225km(760miles)perhour.Atspeedsbeyondaboutfivetimesthevelocityofsound(Mach5),thetermhypersonicflightisemployed.AnobjecttravelingthroughtheEarth’satmosphereatsupersonicspeedgeneratesasonicboom—i.e.,ashockwaveheardonthegroundasasoundlikealoudexplosion.

ThefirstaircrafttoflyatsupersonicspeedswasaBellXS-1rocket-poweredresearchplanepilotedbyMajorCharlesE.YeageroftheU.S.AirForceonOct.14,1947.AfterbeingdroppedfromthebellyofaBoeingB-29mothership,theXS-1brokethe(local)soundbarrierat1,066km(662miles)perhourandattainedatopspeedof1,126km(700miles)perhour,orMach1.06.Thereaftermanymilitaryaircraftcapableofsupersonicflightwerebuilt,thoughtheirspeedwasgenerallylimitedtoMach2.5becauseofproblemscausedbyfrictionalheatingoftheskinoftheplane.

Thefirstsupersonicpassenger-carryingcommercialairplane(orsupersonictransport,SST),theConcorde,wasbuiltjointlybyAérospatialeandBritishAerospace.TheConcordehadamaximumcruisingspeedof2,179km(1,354miles)perhour,orMach2.04.Thisbeautifulairliner,thefirstexampleofwhich

miles)perhour,orMach2.04.Thisbeautifulairliner,thefirstexampleofwhichflewonMarch2,1969,madeitsfirsttransatlanticcrossingonSept.26,1973,andenteredregularservicein1976.Theaircraftprovedatechnicalmiraclebutaneconomicdisaster,however.Neverfinanciallyprofitable,itwasretiredin2003.

TheonlyotherSSTtoseeservicewastheTupolevdesignbureau’sTu-144.TheprototypeofthisSovietSSTmadeitsfirstflightonDec.31,1968,andwassosimilarinappearanceandperformancetothemorehighlypublicizedAnglo-Frenchplanethatitwascalledthe“Concordski.”InitsproductionmodeltheTu-144was65.7metres(215.6feet)inlength,withawingspanof28.8metres(94.5feet).ItsnormalcruisingspeedwasuptoMach2.2,morethantwicethespeedofsound.Amongitsnotablefeatureswere“double-delta”swept-backwings,“moustache”foreplanesthatpivotedoutfromthefuselagejustaftoftheflightdecktoimproveflightcharacteristicsduringtakeoffandlanding,andanosesectionthatcouldbe“drooped”downwardtoimprovethecrew’slineofvisionduringtakeoffandlanding.TheaircrafthadaninauspiciousstartwhenthefirstproductionTu-144crashedatthe1973ParisAirShow.TheaircraftwasputintocommercialserviceontheMoscow–AlmaAtaroute,flyingmail(1975)andthenpassengers(1978),buttheplaneswerepulledfromservicefollowinganothercrashin1978.Latermodelscontinuedtoflyastestbedsforthetechnologyofsupersonicflight.

THECONCORDE

OnJan.21,1976,theAnglo-FrenchConcordeinauguratedtheworld’sfirstscheduledsupersonicpassengerservice.BritishAirwaysinitiallyflewtheaircraftfromLondontoBahrain,andAirFranceflewitfromParistoRiodeJaneiro.BothairlinesaddedregularservicetoWashington,D.C.,inMay1976andtoNewYorkCityinNovember1977.Otherrouteswereaddedtemporarilyorseasonally,andtheConcordewasflownoncharteredflightstodestinationsallovertheworld.

TheConcordewasthefirstmajorcooperativeventureofEuropeancountriestodesignandbuildanaircraft.OnNov.29,1962,BritainandFrancesignedatreatytosharecostsandrisksinproducinganSST.BritishAerospaceandtheFrenchfirmAérospatialewereresponsiblefortheairframe,whileBritain’sRolls-RoyceandFrance’sSNECMA(SociétéNationaled’ÉtudeetdeConstructiondeMoteursd’Aviation)developedthejetengines.TheresultwasatechnologicalmasterpiecethatmadeitsfirstflightonMarch2,1969.TheConcorde’smaximumcruisingspeed

firstflightonMarch2,1969.TheConcorde’smaximumcruisingspeedMach2.04(morethantwicethespeedofsound)allowedtheaircrafttoreducetheflighttimebetweenLondonandNewYorktoaboutthreehours.TheConcordeprovedthatEuropeangovernmentsandmanufacturerscouldcooperateincomplexventures,andithelpedtoensurethatEuropewouldremainatthetechnicalforefrontofaerospacedevelopment.

However,thedevelopmentcostsoftheConcordeweresogreatthattheycouldneverberecoveredfromoperations,so,forreasonsofnationalprestige,theyweresimplywrittenoff.Inaddition,theaircraft’snoiseandoperatingexpenselimiteditsservice.Financiallossesledbothairlinestocutroutes,eventuallyleavingNewYorkCityastheironlyregulardestination.ConcordeoperationswerefinallyceasedbyAirFranceinMay2003andbyBritishAirwaysinOctober2003.Only14oftheaircraftactuallywentintoservice.OneofthemisondisplayataspecialfacilityoftheNationalAirandSpaceMuseumatWashingtonDullesInternationalAirportinVirginia.

CHAPTER6HELICOPTERS,HANGGLIDERS,ANDULTRALIGHTS

Inadditiontofixed-wingaircraft,flightisachievedbyhelicopters,hanggliders,andultralights.Helicopterstaketotheairusingtheprinciplesofverticalflight.Hangglidersemploykite-likewingsforliftandarecontrolledbytheshiftingweightofthepilot’sbody.Ultralightsareadvancedcraftmadewithlightweightmaterialsandpoweredbysmallinternal-combustionengines,electricmotorsfueledbysolarcells,orhumanmusclealone.

THEHELICOPTER

Helicoptersareequippedwithoneormorepower-drivenhorizontalpropellersorrotorsthatenablethecrafttotakeoffandlandvertically,moveinanydirection,orremainstationaryintheair.

Theideaoftakingoffvertically,makingthetransitiontohorizontalflighttothedestination,andlandingverticallyhasbeenforcenturiesthedreamofinventors.Itisthemostlogicalformofflight,dispensingasitdoeswithlargelandingfieldslocatedfarfromcitycentresandtheinevitableinterveningmodesoftravel—automobile,subway,bus—thatflightinconventionalaircraftusuallyrequires.

Butverticalflightisalsothemostdemandingchallengeinflying,requiringmoresophisticationinstructure,power,andcontrolthanconventionalfixed-wingaircraft.Thesedifficulties,solvedovertimebydeterminedengineersand

inventors,madetheprogressofverticalflightseemslowcomparedtothatofconventionalflight.Thefirstusefulhelicoptersdidnotappearuntiltheearly1940s.

Componentsofahelicopter.EncyclopædiaBritannica,Inc.

HISTORY

Oneimportantcharacteristicofthehistoryofverticalflightisthepervasivehumaninterestinthesubject;inventorsinmanycountriestookupthechallengeovertheyears,achievingvaryingdegreesofsuccess.Thehistoryofverticalflightbeganatleastasearlyasabout400CE;therearehistoricalreferencestoaChinesekitethatusedarotarywingasasourceoflift.Toysusingtheprincipleofthehelicopter—arotarybladeturnedbythepullofastring—wereknownduringtheMiddleAges.Duringthelatterpartofthe15thcentury,LeonardodaVincimadedrawingsofahelicopterthatusedaspiralairscrewtoobtainlift.Atoyhelicopter,usingrotorsmadeoutofthefeathersofbirds,waspresentedtotheFrenchAcademyofSciencein1784bytwoartisans,LaunoyandBienvenu;thistoyforecastamoresuccessfulmodelcreatedin1870byAlphonsePénaudinFrance.

Thefirstscientificexpositionoftheprinciplesthatultimatelyledtothesuccessfulhelicoptercamein1843fromSirGeorgeCayley,whoisalsoregardedbymanyasthefatheroffixed-wingflight.Fromthatpointon,averitablegenepoolofhelicopterideaswasspawnedbynumerousinventors,almostentirelyinmodelorsketchform.Manyweretechnicaldeadends,butotherscontributedaportionoftheultimatesolution.In1907thereweretwosignificantstepsforward.OnSeptember29,theBreguetbrothers,LouisandJacques,undertheguidanceofthephysiologistandaviationpioneerCharles

Jacques,undertheguidanceofthephysiologistandaviationpioneerCharlesRichetmadeashortflightintheirGyroplaneNo.1,poweredbya45-horsepowerengine.TheGyroplanehadaspiderweblikeframeandfoursetsofrotors.Thepilotedaircraftliftedfromthegroundtoaheightofabouttwofeet,butitwastetheredandnotunderanycontrol.BreguetwentontobecomeafamousnameinFrenchaviation,andintimeLouisreturnedtosuccessfulworkinhelicopters.Later,inNovember,theircountrymanPaulCornu,whowasabicyclemakerliketheWrightbrothers,attainedafreeflightofabout20seconds’duration,reachingaheightofonefootinatwin-rotorcraftpoweredbya24-horsepowerengine.Anothermanwho,liketheBreguets,wouldflirtwiththehelicopter,goontomakehisnamewithfixed-wingaircraft,andthenlaterreturntothechallengeofverticalflight,wasIgorSikorsky,whomadesomeunsuccessfulexperimentsataboutthesametime.

Thenext25yearswerecharacterizedbytwomaintrendsinverticalflight.Onewasthewidespreadofminorsuccesseswithhelicopters;thesecondwastheappearanceandapparentsuccessoftheautogiro.

Thehelicoptersawincrementalsuccessinmanycountries,andthefollowingshortreviewwillhighlightonlythosewhosecontributionswereultimatelyfoundinsuccessfullydevelopedhelicopters.In1912theDanishinventorJacobEllehammermadeshorthopsinahelicopterthatfeaturedcontrarotatingrotorsandcyclicpitchcontrol,thelatteranimportantinsightintotheproblemofcontrol.OnDec.18,1922,acomplexhelicopterdesignedbyGeorgedeBothezatfortheU.S.ArmyAirForceliftedoffthegroundforslightlylessthantwominutes,underminimumcontrol.InFranceonMay4,1924,ÉtienneOehmichenestablishedadistancerecordforhelicoptersbyflyingacircleofakilometre’slength.

InSpaininthepreviousyear,onJan.9,1923,JuandelaCiervamadethefirstsuccessfulflightofanautogiro,aflyingmachinethatoperatesonadifferentprinciplethanahelicopter;itsrotorisnotpoweredbutobtainsliftbyitsmechanicalrotationastheautogiromovesforwardthroughtheair.Anautogirohastheadvantageofarelativelyshorttakeoffandanearverticaldescent.ThesubsequentsuccessofCierva’sautogirosandthoseofhiscompetitorsseemedtocastapallonthefutureofhelicopterdevelopment.Autogiroswererapidlyimprovedandweremanufacturedinseveralcountries,seemingtofillsuchausefulnichethattheytemporarilyovershadowedthehelicopter.Ironically,however,thetechnologyoftherotorheadandrotorbladedevelopedfortheautogirocontributedimportantlytothedevelopmentofthesuccessfulhelicopter,whichintimemadetheautogiroobsolete.

In1936GermanysteppedtotheforefrontofhelicopterdevelopmentwiththeFockeAchgelisFa61,whichhadtwothree-bladedrotorsmountedonoutriggersandpoweredbya160-horsepowerradialengine.TheFa61hadcontrollablecyclicpitchandsetnumerousrecords,including,in1938,analtitudeflightof3,418metres(11,243feet)andacross-countryflightof230km(143miles).In1938theGermanaviatorHannaReitschbecametheworld’sfirstfemalehelicopterpilotbyflyingtheFa61insidetheDeutschland-HalleinBerlin.Itwasbothatechnicalandapropagandatriumph.GermanycontinueditshelicopterdevelopmentduringWorldWarIIandwasthefirsttoplaceahelicopter,theFlettnerKolibri,intomassproduction.

AUTOGIROS

Theautogiro(alsospelledautogyro)wasformanyyearsintheearly20thcenturythemostreasonablealternativetothehelicopterasameansofverticalflight.Themachineemployedapropellerforforwardmotionandafreelyrotating,unmotorizedrotorforlift.Becausetherotorisnotpowered,theautogirodoesnothavetocontendwithtorque(thetendencyoftheaircrafttoturnintheoppositedirectionoftherotor)andthusavoidedmanyofthecontrolproblemsthatimpededthedevelopmentofthehelicopter.Theautogiro’srotorisdesignedsothatabladesetatalowpositiveangleofpitchwillrotateautomaticallyaslongasanairstreamiskeptflowingthroughtherotor(autorotation).Astheautogiroispropelledforwardthroughtheair,withastreamofairflowingupwardthroughitsrotor,liftisgenerated.Controliseffectedinpartthroughauniversaljointattherotorhead,whichtiltsthebladescreatingaforcethatpullstheautogirointhedirectionofthetilt.Anelevatorandrudderaremaintainedwithinthepropellerslipstreamforadditionalcontrol.

Autogirosbroughtaviatorsclosertothedreamoflandingvertically,buttheystillhadtotaxifortakeoff,andtheyrequiredaforwardairspeedinordertodrivetherotor.Bycontrast,thehelicopter,withitsengine-drivenrotor,wascapableofbothverticaltakeoffandlanding.ProspectsforcommercialdevelopmentoftheautogiroevaporatedwiththesuccessofthemoreefficienthelicopterafterWorldWarII.

IntheUnitedStates,aftermanysuccesseswithcommercialflyingboats,Igor

Sikorskyturnedhisattentiontohelicoptersonceagain,andafteralongperiodofdevelopmenthemadeasuccessfulseriesoftestflightsofhisVS-300in1939–41.Essentiallyatestaircraftdesignedforeasyandrapidmodification,theVS-300wassmall(weighingabout500kg,or1,100pounds)andwaspoweredbya65-horsepowerLycomingengine.Yetitpossessedthefeaturesthatcharacterizemostmodernhelicopters:asinglemainthree-bladedrotor,withcollectivepitch,andatailrotor.AssuccessfulastheVS-300was,however,italsoclearlyshowedthedifficultiesthatallsubsequenthelicopterswouldexperienceinthedevelopmentprocess.Formanyyears,comparedwithconventionalaircraft,helicopterswereunderpowered,difficulttocontrol,andsubjecttomuchhigherdynamicstressesthatcausedmaterialandequipmentfailures.YettheVS-300ledtoalonglineofSikorskyhelicopters,anditinfluencedtheirdevelopmentinanumberofcountries,includingFrance,England,Germany,andJapan.

AfterWorldWarIIthecommercialuseofhelicoptersdevelopedrapidlyinmanyroles,includingfirefighting,policework,agriculturalcropspraying,mosquitocontrol,medicalevacuation,andcarryingmailandpassengers.

Theexpandingmarketbroughtadditionalcompetitorsintothefield,eachwithdifferentapproachestotheproblemofverticalflight.TheBellAircraftCorporation,undertheleadershipofArthurYoung,beganitslong,distinguishedhistoryofvertical-flightaircraftwithaseriesofprototypesthatledtotheBellModel47,oneofthemostsignificanthelicoptersofalltime,incorporatinganarticulated,gyro-stabilized,two-bladerotor.FrankPiaseckicreatedthePiaseckiHelicopterCorporation;itsdesignsfeaturedatandem-rotorconcept.Theuseoftwintandemrotorsenabledhelicopterstogrowtoalmosttwicetheirprevioussizewithoutthedifficultyofcreatingverylargerotorblades.Inaddition,theplacementofthetwinrotorsprovidedalargecentreofgravityrange.Thecompetitionwasinternational,withrapidprogressmadeintheSovietUnion,theUnitedKingdom,France,Italy,andelsewhere.

Turboshaftenginedrivingahelicopterrotoraspropulsor.CopyrightEncyclopædiaBritannica,Inc.;renderingforthiseditionbyRosenEducationalServices

Toanevengreaterextentthanfixed-wingaircraft,thedevelopmentofthehelicopterhadbeenlimitedbyenginepower.Reciprocatingengineswereheavy,noisy,andlessefficientathighaltitude.Thefirstapplicationofjet-enginetechnologytothehelicopterwasaccomplishedin1951bytheKamanAircraftCorporation’sHTK-1,whichhadKaman’spatentedaerodynamicservo-controlledrotorsinthe“synchropter”configuration(i.e.,side-by-siderotorswithintermeshingpathsofbladetravel).

Inconventionalaircraftthepowerofthejetenginewasusedprimarilyforincreasedspeed.Inthehelicopterthethrustofthejetturbinehadtobecapturedbyagearboxthatwouldturntherotor.Thejetenginehadmanyadvantagesforthehelicopter—itwassmaller,weighedlessthanapistonengineofcomparablepower,hadfarlessvibration,andusedlessexpensivefuel.TheFrenchSNCA-S.E.3130AlouetteIImadeitsfirstflightonMarch12,1955,poweredbyaTurbomecaArtousteIIturbineengine.Itrapidlybecameoneofthemostinfluentialhelicoptersintheworldandstartedatrendtowardjet-poweredhelicopterseverywhere.

Therearenowavastnumberofhelicoptertypesavailableonthemarket,rangingfromsmalltwo-personprivatehelicoptersthroughlargepassenger-carryingtypestoworkvehiclescapableofcarryinghugeloadstoremoteplaces.Allofthemrespondtothebasicprinciplesofflight,but,becauseoftheuniquenatureofthehelicopter’srotorandcontrolsystems,thetechniquesforflyingthemdiffer.Thereareothertypesofvertical-liftaircraft,whosecontrolsandtechniquesareoftenablendoftheconventionalaircraftandthehelicopter.Theyformasmallpartofthetotalpictureofflightbutareofgrowingimportance.

PRINCIPLESOFFLIGHTANDOPERATION

Unlikefixed-wingaircraft,thehelicopter’smainairfoilistherotatingbladeassembly(rotor)mountedatopitsfuselageonahingedshaft(mast)connectedwiththevehicle’sengineandflightcontrols.Incomparisontoairplanes,thetailofahelicopterissomewhatelongatedandtheruddersmaller;thetailisfittedwithasmallantitorquerotor(tailrotor).Thelandinggearsometimesconsistsofapairofskidsratherthanwheelassemblies.

Thefactthatthehelicopterobtainsitsliftingpowerbymeansofarotating

airfoil(therotor)greatlycomplicatesthefactorsaffectingitsflight,fornotonlydoestherotorturnbutitalsomovesupanddowninaflappingmotionandisaffectedbythehorizontalorverticalmovementofthehelicopteritself.Unliketheusualaircraftairfoils,helicopterrotorairfoilsareusuallysymmetrical.Thechordlineofarotor,likethechordlineofawing,isanimaginarylinedrawnfromtheleadingedgetothetrailingedgeoftheairfoil.

Therelativewindisthedirectionofthewindinrelationtotheairfoil.Inanairplane,theflightpathofthewingisfixedinrelationtoitsforwardflight;inahelicopter,theflightpathoftherotoradvancesforward(tothehelicopter’snose)andthenrearward(tothehelicopter’stail)intheprocessofitscircularmovement.Relativewindisalwaysconsideredtobeinparallelandoppositedirectiontotheflightpath.Inconsideringhelicopterflight,therelativewindcanbeaffectedbytherotationoftheblades,thehorizontalmovementofthehelicopter,theflappingoftherotorblades,andwindspeedanddirection.Inflight,therelativewindisacombinationoftherotationoftherotorbladeandthemovementofthehelicopter.

Likeapropeller,therotorhasapitchangle,whichistheanglebetweenthehorizontalplaneofrotationoftherotordiscandthechordlineoftheairfoil.Thepilotusesthecollectiveandcyclicpitchcontrol(seebelow)tovarythispitchangle.Inafixed-wingaircraft,theangleofattack(theangleofthewinginrelationtotherelativewind)isimportantindetermininglift.Thesameistrueinahelicopter,wheretheangleofattackistheangleatwhichtherelativewindmeetsthechordlineoftherotorblade.

Angleofattackandpitchanglearetwodistinctconditions.Varyingthepitchangleofarotorbladechangesitsangleofattackandhenceitslift.Ahigherpitchangle(uptothepointofstall)willincreaselift;alowerpitchanglewilldecreaseit.Individualbladesofarotorhavetheirpitchanglesadjustedindividually.

Rotorspeedalsocontrolslift—thehighertherevolutionsperminute(RPM),thehigherthelift.However,thepilotwillgenerallyattempttomaintainaconstantrotorRPMandwillchangetheliftforcebyvaryingtheangleofattack.

Aswithfixed-wingaircraft,airdensity(theresultofairtemperature,humidity,andpressure)affectshelicopterperformance.Thehigherthedensity,themoreliftwillbegenerated;thelowerthedensity,thelessliftwillbegenerated.Justasinfixed-wingaircraft,achangeinliftalsoresultsinachangeindrag.Whenliftisincreasedbyenlargingtheangleofpitchandthustheangleofattack,dragwillincreaseandslowdowntherotorRPM.AdditionalpowerwillthenberequiredtosustainadesiredRPM.Thus,whileahelicopteris

willthenberequiredtosustainadesiredRPM.Thus,whileahelicopterisaffectedlikeaconventionalaircraftbytheforcesoflift,thrust,weight,anddrag,itsmodeofflightinducesadditionaleffects.

Inahelicopter,thetotalliftandthrustforcesgeneratedbytherotorareexertedperpendiculartoitsplaneofrotation.Whenahelicopterhoversinawindlesscondition,theplaneofrotationoftherotor(thetip-pathplane)isparalleltotheground,andthesumoftheweightanddragforcesareexactlybalancedbythesumofthethrustandliftforces.Inverticalflight,thecomponentsofweightanddragarecombinedinasinglevectorthatisdirectedstraightdown;thecomponentsofliftandthrustarecombinedinasinglevectorthatisdirectedstraightup.Toachieveforwardflightinahelicopter,theplaneofrotationoftherotoristippedforward.(Itshouldbeunderstoodthatthehelicopter’srotormastdoesnottipbutrathertheindividualrotorbladeswithintheplaneofrotationhavetheirpitchanglevaried.)Forsidewardflight,theplaneoftherotationoftherotoristiltedinthedirectiondesired.Forrearwardflight,theplaneoftherotationoftherotoristiltedrearward.

Becausetherotorispowered,thereisanequalandoppositetorquereaction,whichtendstorotatethefuselageinadirectionoppositetotherotor.Thistorqueisoffsetbythetailrotor(antitorquerotor)locatedattheendofthefuselage.Thepilotcontrolsthethrustofthetailrotorbymeansoffootpedals,neutralizingtorqueasrequired.

Thereareotherforcesactinguponahelicopternotfoundinaconventionalaircraft.Theseincludethegyroscopicprecessioneffectoftherotor—thatis,thedissymmetryofliftcreatedbytheforwardmovementofthehelicopter,resultingintheadvancingbladehavingmoreliftandtheretreatingbladeless.Thisoccursbecausetheadvancingbladehasacombinedspeedofthebladevelocityandthespeedofthehelicopterinforwardflight,whiletheretreatingbladehasthedifferencebetweenthebladevelocityandthespeedofthehelicopter.Thisdifferenceinspeedcausesadifferenceinlift—theadvancingbladeismovingfasterandhenceisgeneratingmorelift.Ifuncontrolled,thiswouldresultinthehelicopterrolling.However,thedifferenceinliftiscompensatedforbythebladeflappingandbycyclicfeathering(changingtheangleofpitch).Becausethebladesareattachedtoarotorhubbyhorizontalflappinghinges,whichpermittheirmovementinaverticalplane,theadvancingbladeflapsup,decreasingitsangleofattack,whiletheretreatingbladeflapsdown,increasingitsangleofattack.Thiscombinationofeffectsequalizesthelift.(Bladesalsoareattachedtothehubbyaverticalhinge,whichpermitseachbladetomovebackandforthintheplaneofrotation.Theverticalhingedampensoutvibrationandabsorbstheeffectofaccelerationordeceleration.)Inaddition,inforwardflight,theposition

effectofaccelerationordeceleration.)Inaddition,inforwardflight,thepositionofthecyclicpitchcontrolcausesasimilareffect,contributingtotheequalizationoflift.

Otherforcesactinguponhelicoptersincludeconing,theupwardbendingeffectonbladescausedbycentrifugalforce;Corioliseffect,theaccelerationordecelerationofthebladescausedbytheflappingmovementbringingthemcloserto(acceleration)orfartherawayfrom(deceleration)theaxisofrotation;anddrift,thetendencyofthetailrotorthrusttomovethehelicopterinhover.

CONTROLFUNCTIONS

Ahelicopterhasfourcontrols:collectivepitchcontrol,throttlecontrol,antitorquecontrol,andcyclicpitchcontrol.

Thecollectivepitchcontrolisusuallyfoundatthepilot’slefthand;itisaleverthatmovesupanddowntochangethepitchangleofthemainrotorblades.Raisingorloweringthepitchcontrolincreasesordecreasesthepitchangleonallbladesbythesameamount.Anincreaseinthepitchanglewillincreasetheangleofattack,causingbothliftanddragtoincreaseandcausingtheRPMoftherotorandtheenginetodecrease.Thereversehappenswithadecreaseinpitchangle.

BecauseitisnecessarytokeeprotorRPMasconstantaspossible,thecollectivepitchcontrolislinkedtothethrottletoautomaticallyincreasepowerwhenthepitchleverisraisedanddecreaseitwhenthepitchleverislowered.Thecollectivepitchcontrolthusactsastheprimarycontrolbothforaltitudeandforpower.

Thethrottlecontrolisusedinconjunctionwiththecollectivepitchcontrolandisanintegralpartofitsassembly.ThethrottlecontrolistwistedoutboardtoincreaserotorRPMandinboardtodecreaseRPM.

Theantitorquecontrolsarepedalslinkedtooperateapitchchangemechanisminthetailrotorgearbox.Achangeinpedalpositionchangesthepitchangleofthetailrotortooffsettorque.Astorquevarieswitheverychangeofflightcondition,thepilotisrequiredtochangepedalpositionaccordingly.Theantitorquecontroldoesnotcontrolthedirectionofflight.

Itwasstatedabovethatthelift/thrustforceisalwaysperpendiculartotheplaneofrotationoftherotor.Thecyclicpitchcontrol,astick-typecontrolfoundtothepilot’sright,controlsthedirectionofflightbytippingtheplaneofrotationinthedesireddirection.Thetermcyclicderivesfromthesequentialwayeachblade’spitchischangedsothatittakestheflightpathnecessarytoeffectthe

changeindirection.

THEHANGGLIDER

Hangglidersareaircraftofvariousconfigurationsinwhichthepilotissuspendedbeneaththe(usuallyfabric)wingtoprovidestabilityandcontrol.Theyarenormallylaunchedfromahighpoint.Hangglidersweredevelopedbythepioneersofpracticalflight.InGermany,startingin1891,OttoLilienthalmadeseveralthousandflightsbeforeafatalglidingaccidentin1896.Hepublishedplansofhisglidersandevensuppliedkits.IntheUnitedStatescollaborationbetweenAugustusHerringandOctaveChanuteresultedinsuccessfulflightsofabiplanehanggliderfromdunesinIndianaatthesouthernendofLakeMichiganin1896.Intheseearlydesignsthepilothungfromthearmpitsonparallelbarsbeneaththewings,swinginghipsandlegstocontrolrollandshiftingbackandforthtoinfluencepitch.

Inthehandsofanexperiencedpilot,hangglidersarecapableofsoaring(usingrisingaircolumnstoobtainupwardglidingmovement).Thiscapabilityhasgivenrisetothesportofhanggliding.Modernhangglidingemergedtowardtheendofthe1960s.Intheearly1960senthusiastsinCaliforniawereglidingdowncoastaldunesonhomebuiltdelta-shapedwingstheyhadadaptedfromkitedesignsdevelopedbyFrancisRogalloandhiswife,Gertrude.TheRogallos’kiteshadattractedattentionbecauseofNASA’sinterestinusingthemforspacecraftretrieval.Onthedunescheapmaterialssuchasbambooandplasticsheetingwereused,andtheparallel-barcontrolmethodremained.Aroundthesametime,water-skishowmeninAustraliawereflyingonflatkitestowedbehindspeedboats.Theywereabletocontrolthesenotoriouslyunstableflatkitesbyusingswingseatsthatallowedtheirentirebodyweighttoeffectpitchandroll—agreatimprovementontheparallel-barmethod.WhenaRogallowingwasfittedwithaswingseatbyJohnDickenson,inSydney,Australia,themodernhanggliderwasborn.

OTTOLILIENTHAL

(b.May23,1848,Anklam,Prussia[nowinGermany]–d.Aug.10,1896,Berlin)Trainedasamechanicalengineer,OttoLilienthalestablishedhisownmachineshopandflightfactoryfollowingserviceintheFranco-Prussian

War.Hebegantoconductstudiesoftheforcesoperatingonwingsinastreamofairinthelate1870s.Theresultsofthatresearchappearedin1889inabookentitledDerVogelflugalsGrundlagederFliegekunst(“BirdFlightastheBasisofAviation”)andinanimportantseriesofarticlesthatprovidedafoundationforthefinalefforttoachievemechanicalflight.AstransmittedbyOctaveChanute,Lilienthal’sfriendandAmericancorrespondent,thetablesofdataservedasthestartingpointfortheearliestaircraftdesignsoftheWrightbrothers.

Havingexploredthephysicalprinciplesgoverningwingedflight,Lilienthalbegantodesignandbuildhangglidersonthebasisoftheinformationhehadgathered.Between1891and1896,hecompletedsome2,000flightsinatleast16distinctglidertypes.Hiscareerasabuilderandpilotofgliderscoincidedwiththedevelopmentofhigh-speedandstroboscopicphotography.ImagesofLilienthalflyingthroughtheairaboardhisstandardgliderappearedaroundtheglobeinnewspapersandthegreatillustratedmagazinesoftheperiod.ThosepicturesconvincedmillionsofreadersinEuropeandtheUnitedStatesthattheageofflightwasathand.LilienthalbrokehisbackinaglidercrashonAug.9,1896,anddiedinaBerlinhospitalthenextday.TodayheisseenasoneofthemostsignificantaeronauticalpioneersintheyearsleadinguptotheWrightbrothers.

Bytheearly1970sthesporthadspreadthroughouttheUnitedStatesandintoEurope.Aircraft-qualitymaterialsbegantobeused,andglideperformanceincreasedsteadilythroughimprovementsinwingandharnessdesign.TheoriginalRogalloswithaseatedpilothadglideratiosofabout3:1.Thatis,foreverythreefeettraveledforward,theywoulddescendonefoot.By1999glideratioshadreached15:1.Inadditiontothenow-traditionaldelta-shapedflexiblewings,anewgenerationofrigid,taillesshangglidershasbecomepopular,inwhichcarbonfibreandothercompositematerialsprovidetherequiredblendoflightnessandstrength.Glideratiosinexcessof20:1arepossible,coupledwithtopspeedsofabout100km(60miles)perhour,yettheycanstilllaunchandlandatlittlemorethanwalkingpace.

Likeallotherenginelessaircraft,hangglidersusegravityasthesourceofpropulsion,sotheyarealwayssinkingdownward,justasaskiergoesdownhill.However,byseekingairthatismovingupwardfasterthantheaircraftissinking,

skilledpilotscanremainaloftforhours.Typicalsourcesforsuchliftoccurwherewindisdeflectedupwardbyahillormountainridgeorincolumnsofwarmaircalled“thermals,”whicharecausedbythesunheatingtheEarth’ssurfaceunevenly.Suchistheefficiencyofmodernhangglidersthattheworldstraightdistancerecord,setin2001,is700.6km(435.1miles).Hangglidersarehighlymaneuverable,andtheirsafetyrecordcompareswellwiththatofotheraviationsports.

Internationally,hangglidingisunderthecontroloftheFédérationAéronautiqueInternationale(FAI).Worldchampionshipshavebeenheld,usuallyinalternateyears,eversincethefirstinKössen,Austria,in1975.

THEULTRALIGHT

Ultralightswereoriginallyhangglidersadaptedforpowerbytheinstallationofsmallenginessimilartothoseusedinchainsaws.However,theyhavematuredintospeciallydesignedaircraftofverylowweightandpowerbutwithflyingqualitiessimilartoconventionallightaircraft.Theyareintendedprimarilyforpleasureflying,althoughadvancedmodelsarenowusedfortraining,policepatrol,andotherwork,includingaproposeduseincombat.Experimentalultralightshavebeendesignedtomakeuseofhumanandsolarpower.Theseareverylightweight,sophisticatedaircraft,designedwithheavyrelianceoncomputersandusingthemostmodernmaterials.

Whoopingcranesfollowinganultralightaircraft.InternationalCraneFoundation,Baraboo,WI

GeneralAtomicsMQ-1Predator,areconnaissanceunmannedaerialvehicleoftheU.S.AirForce,2006.DaveCibley—214thReconnaissanceGroup/U.S.AirForce

ThefirstgreatexponentofultralightaircraftwasPaulMacCready(1925–2007),anAmericanaerodynamicistwhostartedsailplaningin1947andwasU.S.soaringchampionin1948,1949,and1953,aswellasinternationalchampionin1956.Hewasheadofhisownfirm,AeroVironment,inPasadena,Calif.,workingontheimprovementofairquality,theconservationofenergy,andthederivationofpowerfromwindandwater.OnAug.23,1977,atShafterAirportnearBakersfield,Calif.,MacCready’sGossamerCondor,pedaledandpilotedby137-pound(62-kg)BryanAllen,abicyclistandhang-gliderenthusiast,completedthecourserequiredtowintheKremerPrizeof£50,000($95,000),clearinga10-foot-(3-metre-)highstart-and-finishlinewhilemakingafigure-eightflightaroundtwopylonssethalfamileapart.Thetotaldistanceflownwas1.15miles(1.85km)in6minutes27.05seconds,atatopspeedof11miles(18km)perhour.The70-pound(32-kg)planehada96-foot(29-metre)wingspan.

Asubsequent,morestreamlinedMacCreadyplane,theGossamerAlbatross,waspedaledandpilotedbyAllenfromnearFolkestone,Kent,Eng.,toCapeGris-Nez,France,adistanceof23miles(37km),in2hours49minutes,onJune12,1979.Thisflightwonthe£100,000KremerPrizeforthefirstman-propelledflightacrosstheEnglishChannel.Theplanehadawingspanof93feet10inches(28.6metres),weighed70pounds(32kg),andwasconstructedofMylar,polystyrene,andcarbon-fibrerods.

OnJuly7,1981,theSolarChallenger,asolar-poweredplanedesignedbyMacCready,flewfromthePointoiseCormeillesairport,nearParis,tothe

ManstonRoyalAirForceBase,inKent,Eng.,adistanceof160miles(258km),in5hours23minutesatanaveragespeedofabout30miles(48km)perhourandacruisingaltitudeof11,000feet(3,350metres).ThepilotwasStephenPtacek,weighing122pounds(55kg).Theplane,poweredby16,128solarcellsconnectedtotwoelectricmotors,weighed210pounds(95kg)andhadawingspanof47feet(14.3metres).

BertrandPiccard,1999.BreitlingSA

Macready’sworkhasbeencontinuedbyBertrandPiccard(1958–),aSwissaviatorwhoin1999,withBritishco-pilotBrianJones,completedthefirstnonstopcircumnavigationoftheglobebyballoon.In2003,Piccard—withSwissengineerandpilotAndréBorschberg—launchedSolarImpulse,aprojectthathadtheultimategoalofdevelopingandlaunchingasolar-poweredairplanecapableofcircumnavigatingtheglobe.AmajorsteptowardthatgoalwastakenwhenaSolarImpulseplanepilotedbyBorschbergcompleteda26-hourflightoverSwitzerlandonJuly7–8,2010,becomingthefirstsolar-poweredaircrafttoflythroughthenight.

flythroughthenight.

CHAPTER7AIRPORTS

Anairportisasiteandinstallationforthetakeoffandlandingofaircraft.Anairportusuallyhaspavedrunwaysandmaintenancefacilitiesandservesasaterminalforpassengersandcargo.

Therequirementsforairportshaveincreasedincomplexityandscalesincetheearliestdaysofflying.BeforeWorldWarIIthelandingandtakeoffdistanceofmostpassenger-transportaircraftwasatmost600metres(2,000feet).Additionalclearareaswereprovidedforblindlandingsorbad-weatherruns,butthetotalareainvolvedrarelyexceeded200hectares(500acres).

Itwasnotuntilthegeneralintroductionofheavymonoplanesfortransport,suchastheDouglasDC-3,duringthelate1930sthatextensivetakeoffandlandingdistanceswereneeded.Eventhen,theprewarairfieldsatNewYorkCity(LaGuardia),London(Croydon),Paris(LeBourget),andBerlin(Tempelhof)werelaidoutonsitesclosetothecitycentres.Becauseeventransportaircraftoftheperiodwererelativelylight,pavedrunwayswereararity.Croydon,Tempelhof,andLeBourget,forexample,alloperatedfromgrassstripsonly.Earlyairportswerealsomajorcentresofleisureactivity,oftenattractingmorevisitorsthanpassengers.In1939LaGuardiaAirportattractedalmost250,000visitorspermonth,reachingapeakof7,000inoneday,comparedwithamaximumdailythroughputofonly3,000passengers.In1929Berlin’sairportreported750,000visitorsandboastedarestaurantthatcouldseat3,000peopleontheroofofthepassengerterminal.Thestatusofprewarairportsasmajor

socialcentreswasreflectedintheirdesign,especiallywheretherequirementsofcatering,observationdecks,andparkingwereparamount.Indeed,therequirementsofaircraftandpassengerswerenotatalldominantatearlyairfields.

Muchlong-distanceairtransportwashandledbythelargeseaplanesknownasflyingboatsorclippers.Theseaircraft,thoughslowandoflimitedrange,offeredalevelofcomfortthatwasnecessaryforlong-distancetravel.Airterminalfacilitieswerenecessarilyconstructedclosetolargeopenstretchesofwater.LaGuardiaAirportandSantosDumontAirportinRiodeJaneiroareexamplesofairportsthatstilloperateonsitesoriginallychosenfortheirabilitytohandlelargeseaplanes.ThelargefacilitiesatSouthamptonWaterintheUnitedKingdomhavenowdisappeared,buttheartificiallakeatLinateAirportnearMilan,Italy,isstilltobefoundclosetothepresentadministrationfacilities.

Thevastmajorityofairfieldsthroughouttheworldarestillrelativelysimplefacilities.Evennow,manyhaveunpavedrunwaysoratmostlightlypavedrunwayswithtinyterminaloradministrationbuildings,arudimentarycontroltower,andcrudelandingaids.Suchfacilitiescandealonlywithlightaircraftandanegligibleflowofpassengersorfreight.Heavyairtraffic,ontheotherhand,isnowalmostentirelyhandledbysophisticatedairportfacilitiesthatcanaccommodatetheneedsofcrew,passengers,andfreightandthegreatrangeofaircrafttypesthathaveevolvedtomeettheneedsofmodernairtransportandgeneralaviation.

Morethan100airportsaroundtheworldnowhandleatleast10millionpassengerseachperyear;nearlyhalfoftheseareintheUnitedStates.Dozensofairportsregularlymovemorethan30millionpassengersonayearlybasis,andalmostadozen,rangingfromtheHartsfieldAtlantaInternationalAirportintheU.S.stateofGeorgiatoLondonHeathrowAirportintheUnitedKingdomtoBeijingCapitalInternationalAirportinChina,eachhandlemorethan50million.TheMemphis(Tennessee)InternationalAirport,thehomeairportoftheFedExCorporation’scargoservice,andtheHongKongInternationalAirportaretheworld’slargestcargoshippers,eachofwhichhandlednearlyfourmilliontonsin2007.

AerialviewofChicago’sO’HareInternationalAirport,showingrunwaysandterminalsplowedfreeofsnow.O’HareisoneofthebusiestairportsintheUnitedStates.©Comstock/Jupiterimages

Inordertomeettheincreasingdemandforairtravel,largetransportaircraftpoweredbymultiplejetandturbopropengineshavebeenbuilt.Suchaircraftrequireextensivegroundfacilities,runways,taxiways,fire-fightingandrescueservices,passenger-andcargo-handlingfacilities,accesstocarparkingandpublictransport,lighting,navigationalandapproachaids,andvarioussupportfacilitiessuchascatering,meteorology,andgovernmentalinspection.Inordertobeattractivelyconvenient,thecomplexofactivitiesandfacilitiesthatmakeupamodernairportmustbelocatedsufficientlyclosetothemaincentresofworldpopulation.Atthesametime,theymustbeadequatelydistant,sothattheenvironmentalproblemsassociatedwiththenoiseoflargeaircraftandtheactivitiesoflargenumbersofpassengers,workers,andvisitorsdonotbecomeintolerabletothecitiesthatareserved.

MODERNAIRPORTS

Thelargestairportsintheworldemploymorethan100,000workerseach.Theyareimmenselycomplexentitieswithregardtothephysicalfacilitiesthattheycomprise,theorganizationsthatareactivewithintheirboundaries,andtheservicesthatareprovidedinconjunctionwiththeiroperation.

Physicalfacilitiesincluderunways,taxiways,aprons,andstrips,whichareusedforthelandingandtakeoffofaircraft,forthemaneuveringandpositioningofaircraftontheground,andfortheparkingofaircraftinordertoloadanddischargepassengersandcargo.Forthesafelandingandtakeoffofaircraft,lightingandradionavigationalaidsareprovided.Thesearesupplementedby

lightingandradionavigationalaidsareprovided.Thesearesupplementedbyairfieldmarkings,signsandsignals,andairtrafficcontrolfacilities.Supportfacilitiesontheairsideofthefieldincludemeteorology,fireandrescue,powerandotherutilities,aircraftmaintenance,andairportmaintenance.Landsidefacilitiesarethepassengerandcargoterminalsandtheaccesssystem,whichincludesparking,roads,publictransportfacilities,andloadingandunloadingareas.

Manyorganizationsareinvolvedintheoperationofamodernairport.Overallmanagementisusuallyinthecontrolofanorganization,authority,orcompanythatholdsalicensetooperatethefacility.Thislicenseisgrantedsubjecttoajudgmentbythenationalcivilaviationauthoritiesthatthemanagingbodyisfitandcompetenttorunanairportwithinnationaland,ifapplicable,internationallawsgoverningsafetyandoperations.Whileoverallresponsibilityforefficient,safe,andlegaloperationlieswiththeairportmanagement,manyoftheindividualservicesatanairportareprovidedbyotherorganizations.Suchorganizationsincludeairlines;airtrafficcontrolauthorities;groundhandlingcompanies;fixed-baseoperators;concessionaires;securityorganizations;governmentalagenciesresponsibleforcustoms,immigration,healthcontrol,andpolice;supportcompaniesprovidingflightcatering,fueling,aircraftengineering,andmaintenance;aeroclubs;andflyingschools.Sincetheearly1980s,whenprivatizationbegantosweepthroughcivilaviation,terminal-operationcompanieshavealsobecomemorefrequent,suchasthosethatownterminalsinBirmingham,Eng.;Brussels;andToronto.

Airportservicesrelatedtotheaircraftarefrequentlyreferredtoasairside.Manyoftheseservicesareconcentratedontheapron,orramp,whichisthatpartoftheoperationalsurfaceadjacenttotheterminalswhereaircraftaremaneuveredorparked.Theyincludetheapronhandlingofaircraft,airsidepassengertransfertotheaircraft,thehandlingofbaggageandcargo,aircraftfueling,cateringandcabincleaning,enginestarting,deicing,groundpowerandair-conditioning,andminormaintenanceengineering.Otherairsideservicesarerunwayinspection,lightingandnavigationalaids,firefightingandrescue,airsidemaintenance,andairtrafficcontrol.Amongthelandsideservicesarethoserelatedtogroundpassengerhandling;theseincludecheck-in,security,customsandimmigration,baggagedelivery,information,catering,cleaningandmaintenance,shopsandconcessionaryfacilities,automobilerental,groundtransportation,porters,specialhelpfortheelderlyandhandicapped,automobileparking,andpublictransportation(includingtaxis).Inaddition,becauseairportsemploysuchalargenumberofworkers,extensiveprovisionmustbemadefor

theirdailyrequirements.

OPERATIONALREQUIREMENTS

Itisobviouseventothemostcasualobserverthatthereisalargevariationintheappearanceandlayoutofairportfacilities.Simpleairportsdesignedtoaccommodatelightaircraftareessentiallysimilar,but,asairportsbecomelargerandmorecomplex,thusaccommodatingmorepassengersandcargo,theirindividualrequirementsaffecttheirlayoutsandensurethateachbecomesrecognizablydifferent.

Theprincipaldeterminantsofairportlayoutarethenumberofrunwaysandtheirorientation,theshapeoftheavailablesite,andconstraintsatthesitebothonthegroundandintheair.Thelocationandorientationofrunwaysisgovernedinturnbytheneedtoavoidobstacles,particularlyduringlandingandtakeoffprocedures.Forthelargestairports,obstaclestoairnavigationmustbeconsidereduptoabout15km(10miles)fromtherunways.Runwayconfigurationsmustalsoensurethat,for95percentofthetime,aircraftcanapproachandtakeoffwithouteithercrosswindsortailwindsthatwouldinhibitoperations.Atthesmallestairports,lightaircraftareunabletooperateincrosswindsgreaterthan10knots;atallairports,operationintailwindsinexcessof10knotsisnotrecommendedbyaircraftmanufacturers(10knots,ornauticalmilesperhour,isequaltoabout12statutemilesperhouror19kmperhour).

RUNWAYCONFIGURATIONS

Theoperationalcapacityofanairport,whichisusuallydefinedasthemaximumpossiblenumberofaircraftlandingsandtakeoffs,isdeterminedbythenumberofrunwaysthatareavailableforuseatanyonetime.Thevastmajorityofairportsaroundtheworldhavethesimplestpossiblelayout,asinglerunway.Wherecrosswindswouldbehighforanunacceptableproportionofoperationaltime,atwo-runwayconfigurationisnecessary,usuallyintheformofamainrunwayandanauxiliarycrosswindrunway.Dependingontheshapeofthesiteandtheavailabilityofland,thecrosswindfacilitycantakeonacrossedconfigurationoranopenorclosedVlayout.Wherevisibilityisgoodandaircraftcanoperateundervisualflightrules(VFR),operationalcapacityincreasesfromthelowestlevel,crossedrunways,throughtheclosedVandopenVconfigurations.However,inpoorvisibilityorundercertainconditionsofveryheavyairtraffic,aircraftmustoperateunderthestrictinstructionsandrulesofairtrafficcontrolandinstrumentoperation;thesearecalledinstrumentflightrules(IFR).Undersuchconditions,crosswindrunwayscannotbeused

rules(IFR).Undersuchconditions,crosswindrunwayscannotbeusedsimultaneouslywithmainrunways,sothatthecapacitiesofthecrossedandVconfigurationsareequivalenttothatofasinglerunway.

Fourrunwayconfigurations.CopyrightEncyclopædiaBritannica,Inc.;renderingforthiseditionbyRosenEducationalServices

AnincreaseinoperationalcapacityunderVFRispossiblewiththeuseofacloseparallelrunwayconfiguration.MostverylargeairportsmustbeassuredofadequatecapacityevenunderIFRconditions,andthiscanbeachievedbyseparatingtheparallelrunwaysbyaminimumof1,035metres(3,400feet),whichwasthedistanceapprovedbytheInternationalCivilAviationOrganizationonNov.9,1995.Thisindependentparallelconfigurationpermitssimultaneousindependentlandingsandtakeoffsonbothrunways.MunichAirportexemplifiesthistypeofconfiguration.Evengreatercapacityispossibleusingafour-runwayconfigurationofindependentcloseparallels,asisthecaseatLosAngelesInternationalAirport.Withsuchaconfiguration,evenunderIFR,itispossiblefortwoaircrafttolandsimultaneouslywhiletwootheraircrafttakeoff.Anumberoftheworld’slargestairportshavemasterplansthatfeatureeightrunwaysintheformofindependentcloseparallelssupplementedbyothercloseparallelsthatarecapableofcrosswindoperation.However,withpassengeraircraftincreasinginsize,mostcannowoperateincrosswindsof20knotsandabove.Thisreducesthelikelihoodthatconfigurationswithfourcrosswindrunwayswilleverbeconstructed.

Fourparallelrunwayconfigurations.CopyrightEncyclopædiaBritannica,Inc.;renderingforthiseditionbyRosenEducationalServices

RUNWAYPAVEMENTS

Untiltheintroductionofheavymonoplaneaircraftinthelatterpartofthe1930s,civilair-transportaircraftwereabletooperatefromgrassrunwayswithtakeoffdistancesoflessthan600metres(2,000feet).TheadventofheavyaircraftsuchastheDC-3requiredtheprovisionofpavedrunways;atthesametime,takeoffdistancesincreasedtomorethan900metres(3,000feet).Thelengthrequirementsforrunwayscontinuedtoincreaseintothemid-1970s,whenlargecivilianaircraftsuchastheDouglasDC-8andsomemodelsoftheBoeing747requiredalmost3,600metres(12,000feet)ofrunwayatsealevel.(Evenlongerrunwayswerenecessaryathigherelevationsorwherehighambientairtemperaturesoccurredduringoperations.)Thetrendtowardincreasingrunwaylengthscausedmanyproblemsatexistingcivilianairports,whererunwayshadtobeextendedinordertoaccommodatethenewaircraft.Ultimately,pressurebyairportoperatorsandthedevelopmentofturbofanjetenginesarrestedandfinallyreversedthetrend.Sincethe1970s,runwaylengthrequirementshaveactuallydecreased,andthetakeoffandclimbperformanceofcivilianaircrafthasimprovedsubstantially.Thishasbroughtadualbenefitinreducingtheareaoflandrequiredbyanairportandalsoinreducingtheareaaroundtheairportthatisadverselyaffectedbynoiseontakeoff.

Atallbutthesmallestairports,pavementsarenowprovidedforrunways,

Atallbutthesmallestairports,pavementsarenowprovidedforrunways,taxiways,aprons,andanyotherareaswhereaircraftaremaneuvered.Pavementsmustbedesignedinsuchawaythattheycanbeartheloadsimposedbyaircraftwithoutfailure.Apavementmustbesmoothandstableunderconditionsofloadingduringitsexpectedoreconomiclife.Itshouldbefreefromdustandotherparticlesthatcouldbeblownupandingestedintoengines,anditmustbecapableofspreadingandtransmittinganaircraft’sweighttotheexistingsubsoil(orsubgrade)inamannerthatprecludessubsoilfailure.Anotherfunctionofthepavementistopreventweakeningofthesubsoilbymoistureintrusion,especiallyfromrainfallandfrost.

Airfieldpavementsareoftwotypes,rigidandflexible.Rigidpavementsareconstructedofportlandcementconcreteslabsrestingonapreparedsubbaseofgranularmaterialordirectlyonagranularsubgrade.Loadistransmittedthroughtheslabstotheunderlyingsubgradebyflexureoftheslabs.Flexiblepavementsareconstructedofseveralthicknessesofasphaltorbituminousconcretelayersoverlyingabaseofgranularmaterialonapreparedsubgrade.Theyspreadtheconcentratedaircraftwheelloadsthroughouttheirdepthuntiltheloadatthebaseofthepavementislessthanthestrengthoftheinsitusoil.Atalldepthsthestrengthofthepavementshouldbeatleastequaltotheloadsplaceduponitbyaircraftwheels.Thechoiceofpavementtypeisoftendeterminedbyeconomics.Insomepartsoftheworld,Portlandcementconcreteischeaperthanasphalt;inotherparts,theconverseistrue.Forcertainpartsoftheairfield,however,asphalticconcreteisanunsuitablematerialforpavementconstructionbecauseofitsvulnerabilitytodamagebyaviationfuel.Therefore,evenatairportswhereflexibleairfieldpavementsaregenerallyinuse,itisusualforconcretepavementstobeusedwhereaircraftstandontheapronsandatrunwayendswherefuelspillageisfrequent.

NAVIGATIONALAIDS,LIGHTING,ANDMARKING

Onlythesimplestairfieldsaredesignedforoperationsconductedundervisualmeteorologicalconditions(VMC).Thesefacilitiesoperateonlyindaylight,andtheonlyguidancetheyarerequiredtoofferisapaintedrunwaycentrelineandlargepaintednumbersindicatingthemagneticbearingoftherunway.Largercommercialairports,ontheotherhand,mustalsooperateinthehoursofdarknessandunderinstrumentmeteorologicalconditions(IMC),whenhorizontalvisibilityis600metres(2,000feet)orlessandthecloudbase(or“decisionheight”)is60metres(200feet)orlower.Inordertoassistaircraftinapproachesandtakeoffsandinmaneuveringontheground,suchairportsareequippedwithsophisticatedradionavigationalaids(navaids)andvisualaidsin

equippedwithsophisticatedradionavigationalaids(navaids)andvisualaidsintheformoflightingandmarking.NAVIGATIONALAIDSThemostcommonformofnavaidusedfortheapproachphaseofaircraftdescentistheinstrumentlandingsystem(ILS).Thisisaradiosignalthatisbeamedalongthecentrelineoftherunwayandatthecorrectangleofapproach(usually3°abovethehorizontal).Thebeamisinterceptedbyanapproachingaircraftupto24km(15miles)fromthethresholdoftherunway.Informationisgivenconcerningpositionaboveandbelowtheglideslopeanddeviationtotherightorleftofcentreline;consequently,thepilotisabletodeterminefromcockpitinstrumentsadeviationoftheaircraftfromtheproperapproach.

Additionalapproachinformationisgivenvisuallytothepilotintheformoflightingapproachaids.Twosystemsofapproachaidsareinuse:thevisualapproachslopeindicatorsystem(VASIS)andthemoremodernprecisionapproachpathindicator(PAPI).Bothworkontheprincipleofguidinglightsthatshowwhitewhenthepilotisabovetheproperglideslopeandredwhenbelow.

AIRFIELDLIGHTING

Visualguidancetoapproachingaircraftisalsoprovidedbyapproachlightingsystems,aconfigurationofhigh-intensitywhitelightsrunningalongthecentrelineoftherunwayandextendingupto600metres(2,000feet)beyondthethreshold.Atairfieldswhereaircraftoperateinverypoorvisibility,touchdown-zonelightingisprovidedoverthefirst900metres(3,000feet)fromtherunwaythreshold.Theselights,setinpatternsflushwiththerunwaypavement,provideguidanceuptothefinalmomentoftouchdown.

Therunwayitselfisstronglydelineatedbyavarietyofguidancelightsystems.Thethresholdisdesignatedbyalineofgreenlights,andtheedgesandcentrelinearedelineatedbywhitelightsthatshinetowardthemaneuveringaircraftatregularintervals.Thepilotiswarnedoftheapproachingrunwayendbyalineofredlightsattheendoftheusablepavement.Taxiwaysaredelineatedbyblueedgelightsandbygreencentrelinelightsthatalsoappearatregularintervals.

RUNWAYMARKINGS

Considerableadditionalvisualguidanceisgiventopilotsbypaintedmarkingsontherunway.Theformofmarkingindicatesataglancewhetherradio

instrumentguidanceisavailableatanyparticularairfield.Onprecisioninstrumentrunways,therunwayedgesareindicatedbypaintedlines,anddistancesalongtherunwayfromthethresholdareindicatedbypavementmarkings.Inaddition,touchdown-zonemarkingsarepaintedonthepavementimmediatelyafterthethreshold,providingvitalvisualguidanceduringthemomentsimmediatelybeforetouchdownwhenalllightingmaybeobscuredbyfog.

AIRTRAFFICCONTROL

Inthevicinityofairports—especiallylargeairports,whereinpeakconditionsasmanyasthreelandingortakeoffoperationsmayoccureveryminute—thecontrolofaircraftintheairisadifficultbutextremelyimportantoperation.Aircraftrequireverylargeamountsofairspace,butatthesametimetheriskofcollisionmustbesetatverylow,almostnegligible,levels.Becauseaircraftareconcentratedintheairspacearoundairports,acceptablelevelsofcollisionriskcanbeachievedonlybystrictadherencetoproceduresthataresetoutandmonitoredbyairtrafficcontrolauthorities.

Interiorviewofanairporttrafficcontroltoweratdusk.Theairporttrafficcontroltowermanagestakeoffsandallmovementwithintheairport’sterminalcontrolarea.©Comstock/Jupiterimages

Anaircraftinflightfollowsenrouteairtrafficcontrolinstructionsasitfliesthroughsuccessiveflightinformationregions(FIRs).Uponapproachinganairportatwhichalandingistobemade,theaircraftpassesintotheterminalcontrolarea(TCA).Withinthisarea,theremaybeagreatlyincreaseddensityofairtraffic,andthisiscloselymonitoredonradarbyTCAcontrollers,who

continuallyinstructpilotsonhowtonavigatewithinthearea.Theaircraftisthenbroughtintothefinalapproachpattern,atwhichpointcontrolpassestotheapproachcontroller,whomonitorstheaircrafttotherunwayitself.Onceontherunway,thepilotisgiveninstructionsongroundmaneuversbythegroundcontroller,whoseresponsibilityistoavoidconflictingmovementsofaircraftintheoperationalareaoftheairfield.Thegroundcontrollergivesthepilotinstructionsonreachingtheapronstandpositionviatheappropriateturnoffsandtaxiways.Finalpositioningmaybetheresponsibilityofanaproncontroller.Departingaircraftgothroughareverseprocedure,wherebycontrolispassedfromgroundcontroltodeparturecontroltoterminalcontrolareaand,finally,toenroutecontrol.

CARGOFACILITIES

Lessthan1percentofallfreighttonnageiscarriedbyair.Nonetheless,thisstatisticsignificantlyunderestimatestheimportanceofairfreightbecause,invalueofcargomoved,airtransportdominatesallothermodes.Forexample,althoughHeathrowAirporthandlesonlyaboutamilliontonsoffreightperyear,invalueofthroughputitranksasBritain’spremierport.

Asisthecasewithpassengerfacilities,freightterminalsvarygreatlyinthevolumesofmaterialhandled.Consequently,thescaleofthebuildingfacilitiesandthenatureofthehandlingmethodsalsovary.Becauseonly10percentofaircargoiscarriedlooseorinbulk,allmodernair-cargofacilitiesaredesignedtohandlecontainers.Incountrieswherelabourischeapandwherefreightthroughputsattheterminalarenothigh,freight-handlingsystemscanstillbeeconomicallydesignedaroundthemanhandlingconcept.Thisisnotfeasibleindevelopedcountries,wherelabourcostsarehigh.Evenatfacilitieswithsmallthroughputs,freightismovedbymobilemechanicalequipmentsuchasstackers,tugs,andforklifttrucks.Athigh-volumefacilities,amixtureofmobileequipmentandcomplexfixedstackingandmovementsystemsmustbeused.Thefixedsystems,whichrequirecomplexengineeringdesignandmaintenance,areknownastransfervehicles(TVs)andelevatingtransfervehicles(ETVs).

Inthedesignofair-cargofacilities,specialattentionmustbegiventothehandlingofveryheavyandoversizedfreight,perishables,urgentmaterialssuchasserumsandhumandonororgans,high-valuegoodssuchasdiamondsandgold,hazardousgoods,andlivestock.

Anareaofveryfastgrowthintheair-cargobusinessisspecializedmovementbyintegratedcarrierssuchastheU.S.-basedFedExCorporation,

whichoffersdoor-to-doordeliveryofsmallpackagesatpremiumrates.Initsearlyyears,thistypeoffreightgrewbymorethan17percentperannum.Cargoterminalsforthesmall-packagebusinessaredesignedandconstructedseparatelyfromconventionalair-cargoterminals.Theyoperateinadifferentmanner,withallpackagesbeingclearedonanovernightbasis.

ENVIRONMENTALIMPACT

Largeairportsareactuallyurbancomplexesinwhichhigh-populationactivitycentresarecloselyassociatedwithveryextensivepavedareas.Typicallyalargeairportcan,onadailybasis,handlemorethan100,000passengersandsupportaworkingpopulationofmorethan50,000employees.Thesewagesystemofsuchanairportmustcopewithlargedailyflowsofsanitarysewageeffluentand,inaddition,mustaccommodaterunofffromrainandsnowaccumulatingoverseveralhundredacresofimperviouspavement.Thescaleofthesewageproblematmanylargeairportsissuchthatsomefacilitieshavetheirownsewagetreatmentplants,especiallyforsanitarysewage.Becausemanyairportsaresituatedonlow-lyingground,whichismorelikelytoprovidetheflatlandnecessaryforairstrips,thesewagesystemmustoftenincludeextensivepumpingfacilities.

Growingconcernabouttheenvironmentcombinedwiththeincreasingscaleofactivityatmanyairportshasmeantthatrunoffwatercannolongerbedraineddirectlyintobodiesofsurfacewatersuchasriversandlakes.Inparticular,deicingchemicalsusedonaircraftandairfieldpavementsandcleaningchemicalsusedinaircraftmaintenanceareseriouscontaminantsofgroundwaterandsurfacewater.Consequently,someairportsarerequiredtoprovideatleastprimarytreatmentofallrunoffdischarges,andtherearelegalrestrictionsonthenatureofthechemicalsthatcanbeused.Inordertopreventgroundwaterpollution,MunichAirportwasdesignedtoaccommodateexistingflowsofsurfacewateracrosstheentiresiteandwasalsoprovidedwithextensivearrangementsfortherecyclingofdeicingchemicals.

Bytheearly1960s,aircraftnoiseinthevicinityofurbanairportshadbecomeamajorproblem.Thecauseoftheproblemwasarapidlyincreasingnumberofaircraftmovementsandtheintroductionofthefirstgenerationofturbojetaircraftwithlowclimbperformance,suchastheearlymodelsoftheBoeing707andtheDouglasDC-8.Subsequently,publicobjectionsarosetotheplannedexpansionofmosturbanairports.Theseobjectionsoftenheldupexpansionformanyyearsand,incitiessuchasLondonandMunich,ultimatelyseverelymodifiedthedevelopmentofnewairports.Inaddition,noisecurfews

severelymodifiedthedevelopmentofnewairports.Inaddition,noisecurfewswereintroducedatmanyexistingairports,suchasJohnF.KennedyinNewYork,London’sHeathrow,andKingsfordSmithAirportnearSydney.

Inresponsetonationalandinternationalregulationsaimedatcertifyingonlyquieteraircraft,majoreffortshavebeenmadebyaircraftmanufacturerstoreducenoiseatthesource.SuccessivegenerationsofaircrafthavebeenbannedastheyfailedtomeetincreasinglysevererequirementsintroducedbytheInternationalCivilAviationOrganizationandtheU.S.FederalAviationAdministration.Theintroductionofhigh-bypassturbofanenginesandaircraftwithhighclimbperformancehavehelpedconsiderablyinreducingnoise.

Airportscandiminishaircraftnoiseinanumberofways.Hoursofoperationcanbelimitedthroughtheuseofnightcurfews,nightnoisehavingbeenfoundmuchmoreobjectionabletothepublicthandaynoise.Noisyaircraftcanberestrictedorevenbanned.Runwayscanbeselectedtolimitorspreadnoisemoreevenlyoverthecommunity,andapproachanddepartureroutescanbedesignatedoverless-populatedareas.Airlinescanalsobeencouragedtomodifyapproachanddeparturegradientsandoperatingproceduresinordertoreduceenginethrustoverhighlypopulatedareas.Theperformanceoftheoperatorsismonitored,andoffendingoperatorshavefinancialpenaltiesimposeduponthem.Usingsuchmethods,manymajorairports—eventhosethatanticipatelong-termgrowthinpassengernumbersandaircraftmovements—cansignificantlyreducetheexposureofurbanpopulationstoaircraftnoise.

AIRPORTSECURITY

Untilthe1960s,airportsecuritywasrelativelysimple,requiringnothingmorethancivilianpolicetoprovideprotectionagainstconventionalcrimessuchastheft,pickpocketing,vandalism,andbreakingandentering.However,inthe1960scivilaviationbecamearecognizedtargetforpoliticallymotivatedcrimes.Thesecrimescametoincludegeneralactsofterrorism,suchasmassshootingsandbombingsand,especially,aircrafthijacking.

Althoughthefirstaircrafthijackingoccurredin1931inPeru,sucheventswererare,withnomorethanahandfuleachyear,andgenerallywithoutanypoliticalmotive.However,bythelate1960s,politicallymotivatedhijackingstoCubahadbecomecommon.In1969,forexample,therewere87hijackingsworldwide,ofwhich71wererelatedtoCuba,whichtypicallygrantedpoliticalasylumtothehijackers.

TheInternationalCivilAviationOrganization(ICAO),whichquickly

recognizedthatpassengerairlinershadbecomepoliticaltargets,respondedinthedecadesofthe1960sand’70swiththreemajorconventionscovering“unlawfulactsagainstcivilaviation.”Tocombatthecrimesofhijackingandterrorism,thefollowinginternationalconventionsestablishedminimumconditionsforappropriatesecuritycountermeasurestobeadoptedinaninternationalcontext:

•ConventiononOffencesandCertainOtherActsCommittedonBoardAircraft,commonlycalledtheTokyoConvention,wassignedonSept.14,1963,andwentintoforceonDec.4,1969—concernedwithcrimesonboardaircraft,particularlyanycrime

thatjeopardizesthesafetyoftheaircraftanditspassengers;

•ConventionfortheSuppressionofUnlawfulSeizureofAircraft,commonlycalledTheHagueConvention,wassignedonDec.16,1970,andwentintoforceonOct.14,1971—concernedspecificallywiththeoffenceofhijacking,witharecommendationthatitshouldbemadeanextraditableoffenceforallmembercountries;

•ConventionfortheSuppressionofUnlawfulActsAgainsttheSafetyofCivilAviation,commonlycalledthe

MontrealConvention,wassignedonSept.23,1971,andwentintoforceonJan.26,1973—broadenedthescopeofTheHagueConventiontoincludethecrimeofsabotage.

TheseconventionsresultedinmanyICAOrecommendationsfortheenforcementofgreatersecurityatairports.However,becausetheICAOhasnonationaljurisdiction,theorganization’srecommendationsneededtobetranslatedintoindividualnationallaws.FollowingtheTokyoConvention,theICAOmeasureswerewidelyadoptedbymostnationalcivilaviationauthorities,althoughtheefficiencyofthesecurityproceduresadoptedvariedgreatly

throughouttheworld.Countriesthathadnohistoryofdomesticcivilterrorismbecameoverconfidentintheirsecuritymeasures,believingthatonlyinternationalflightswererealtargetsforterroristattacks.However,asterroristactscontinuedtooccuragainstpassengerairliners,securitymeasuresgraduallybecamelesslaxinmostjurisdictions.

Initially,theprincipalobjectiveofsecuritymeasureswastoensurethatpassengerscouldnotboardaircraftwithweaponsorexplosives.Passengerswerescannedwithmagnetometersandsuspiciousindividualsselectedforbodysearches;carry-onbaggagewasroutinelypassedthroughX-raymachines.Publicaccesstotheapronsandoperationalareaswasdenied,exceptforauthorizedstaff,aswasunnecessaryaccesstothenonpublicareasoftheterminal.Ascontrolofpassengersandcarry-onbaggagetightened,hijackingswereincreasinglyreplacedbyactsofsabotagetoaircraft,carriedoutbyexplosivedevicessecretedinbaggagecarriedintheairplane’shold.Bythelate1990s,theICAOhadproducedrecommendationsthatallholdbaggageshouldbescreenedforexplosiveanddangerousdevices.Theoperationalareasofcivilairfieldswereenclosedbysecurityfences,withmannedaccessgatesandvisualsurveillanceofmuchoftheareasbyclosed-circuittelevision.

In2001,theSeptember11attacksproducedaseachangeinmuchofthethinkingsurroundingairportsecurity.Inaperiodoftwohours,asingleterroristorganizationwreakedanunprecedentedlevelofdestructionintheUnitedStatesbyusinghijackedairlinersasmissiles.Forthefirsttime,civiltransportaircraft,loadedwithpassengersand,mostsignificantly,withanearlyfullloadoffuel,hadbeenconvertedtodestructiveweapons.

Authoritiesrespondedtothesehijackingswithanintensificationofsecurityproceduresatairportsaroundtheworld.Passengerandbaggagesearchproceduresweremadesignificantlymorethorough,involvingmorecarefulscreeningforknownterrorists(includingthecreationofvariousno-flyandwatchlistsofriskyindividuals)andpotentiallyproblematiccarry-onitems.Passengerterminalsincreasedthelevelandsophisticationofsecurityequipment,thenumberofstaffemployedinsecurityprocedures,andthespaceprovidedforsecurityoperations.Asaresult,recommendedcheck-intimesfordepartinginternationalpassengersatmanyairportsbecameasmuchasthreehoursbeforescheduleddeparture.

HandbaggageandcheckedbaggagebothbecamesubjecttostrictscrutinyfollowingSept.11,2001.ManyadditionalairportsinstalledX-rayequipment,forspottingmetalitemsinbaggageorconcealedinclothing,andmassiveelectronicdetectionsystems(EDS),whichcandetecttracemoleculesreleased

electronicdetectionsystems(EDS),whichcandetecttracemoleculesreleasedbyexplosivematerials.ThemassiveweightofEDSequipmentfrequentlyrequiresstructuralmodificationstoexistingbuildings,andthesizeoftheequipmentoftenrequiresareallocationoffloorspace.Inmanyairports,installedsecurityequipmentnowmustbeapprovedandcertifiedbythenationalgovernment.

Anotherproblemforsecurityatairportsisthepossibilityofacarortruckbeingloadedwithexplosivesanddetonatednearpeopleorfacilities.Inparticular,thethreatfromsuch“carbombs”forcedgreatercautionwiththelocationandoperationofpassengerpick-upareasandairportparkingfacilities.Parkinggaragesthatwereintegratedintothedesignofthepassengerterminalposeaspecialdanger.Atthoseairportswhereparkingdesignresultsinathreattothesafetyoftheterminalbuildingfrompotentialcarbombs,operationalprocedureshavebeenreevaluatedandchanged.Inmanycases,parkingfacilitiesintegratedintotheterminalitselfhavebeenclosed.

Thethreatofterroristattackshasmeantthat,fortheforeseeablefutureandprobablypermanently,civilaviationcannotreturntoasituationofrelaxedsecurity.Eventually,accesstoairportterminalsmightrequirethatallpersonspassthroughsomeformofsecuritycheckpriortocheck-in,thatallpassengersandbaggagebethoroughlyscrutinizedforweaponsandexplosives,andthatpassengersundergoprofilinginterviewstoidentifypotentialproblemtravelers.

CONCLUSION

Thedreamofflighthasprogressedfarbeyondthedayswhenpeoplewouldwatchthepatternsofsmokerisingintotheairorthesoaringofbirdsonthewindandwonderifitwouldbepossibletoemulatetheiraction.Balloons,thoughsurpassedasameansofairtransportbyfixed-wingairplanes,continuetobeusedforsport,pleasure,andscientificresearch,owingtothesimplicityandreliabilityofthebasiclighter-than-airconcept.

Heavier-than-aircraft—bothfixed-wingairplanesandrotary-winghelicopters—havepassedintotheageofgasturbinepropulsion,advancedavionics,andlightweightcompositematerials.Theirprimacyasglobaltransportisuncontested,thoughitisaprimacythatisnotwithoutchallengesinaneraofrisingfuelprices,growingconcernsoverairpollution,andwastefullanduse.Perhapsmostimportantinthemindsoftravelersisagreaterneedforsecurityagainstmishapsandviolence.Despitethesechallenges,thedreamofflight,sinceitsrealizationintheearly20thcentury,continuestoinspirepeople’sseeminglyinnatedesiretodefyspace,time,andtheforceofgravityby

seeminglyinnatedesiretodefyspace,time,andtheforceofgravitybytransportingthemselvesthroughtheairtofar-offplaces.

APPENDIX

GLOSSARYactuateToputintomechanicalactionormotion.

adiabaticOccurringwithoutlossorgainofheat.

aeolipileAsteamturbinethatconsistedofaspherewithoneormoreprojectingbenttubes,outofwhichsteampassedandturnedthesphere.

aeronautOnewhopilotsortravelsinanairshiporballoon.

ballastAheavysubstanceplacedinsuchawayastoimprovestabilityandcontrolofamovingvehicleorvessel.

buoyancyTheabilityofabodytoriseinfluid,gas,orair.

calorimeterAnapparatusformeasuringquantitiesofabsorbedoremittedheat,orfordeterminingspecificheats.

camberedCurvingorarchingupwardinthemiddle.

canardAsmallairfoilorprojectionlocatedinfrontofanaircraft’swingthatcanincreasetheaircraft’sperformance.

coningTheupwardbendingoftherotorbladesofahelicopterasitlifts.

CorioliseffectAneffectthatcausesmaterialmovingonarotatingplanettoappeartobedeflectedtoeithertherightortheleft.

dirigibleAlighter-than-aircraftequippedwithsteeringcontrols,alsocalledsimplyan“airship.”

fuselageThecentralbodyportionofanaircraftdesignedtoaccommodatecrewandpassengersorcargo.

gimbalAdevicethatpermitsabodytoinclinefreelyinanydirectionorsuspendsitsothatitwillremainlevelwhenitssupportistipped.

gondolaAnoftenspherical,airtightenclosuresuspendedfromaballoonforcarryingpassengersorinstruments.

hermeticSealedinanairtightfashion.

liftAnaerodynamicforceperpendiculartotherelativewind,resultinginanupwardforcethatopposesthepullofgravity;necessaryforflight.

monocoqueAtypeoffuselageconstructioninwhichtheouterskincarriesallor

amajorpartofthestresses.

ornithopterAnaircraftdesignedtoderiveitschiefsupportandpropulsionfromflappingwings.

pneumaticMovedorworkedbyairpressure.

propulsionTheactorprocessofdrivingforwardoronwardbyorasifbymeansofaforcethatimpartsmotion.

stratosphereLayeroftheatmosphereabovethetroposphere.

tensilestrengthThegreatestlongitudinalstressasubstancecanbearwithouttearingapart.

trimotorAnairplanepoweredbythreeengines.

troposphereThelowestregionofEarth’satmosphere,wherenearlyallwatervapourexistsandessentiallyallweatheroccurs.

zeppelinArigidairshipconsistingofacylindricaltrussedandcoveredframesupportedbyinternalgascells.

BIBLIOGRAPHY

BALLOONFLIGHT

TomD.Crouch,LighterThanAir:AnIllustratedHistoryofBalloonsandAirships(2009),coversthedevelopmentoflighter-than-airflightfromArchimedestomodernsportballooning.HaroldG.DickandDouglasH.Robinson,GoldenAgeoftheGreatPassengerAirships(1985),focusesontheGrafZeppelinandtheHindenburg.BalloonFlyingHandbook,rev.ed.(2008),bytheU.S.FederalAviationAdministration,isforstudentpilotslearningtoflyballoonsaswellasforexperiencedpilotsseekingadvancedproficiency.

AIRPLANES

TomD.Crouch,ADreamofWings:AmericansandtheAirplane,1875–1905(1981,reissued2002),isastudyoftheriseofacommunityofAmericanengineersandscientistswholaidthefoundationfortheinventionoftheairplane.CharlesHarvardGibbs-Smith,TheRebirthofEuropeanAviation,1902–1908(1974),describestheimpactoftheWrightbrothersonEuropeanflightexperimenters.RichardP.Hallion,TakingFlight:InventingtheAerialAgefromAntiquitytotheFirstWorldWar(2003),providesagoodsurveyoftheearlyhistoryofflight.RobertWohl,APassionforWings:AviationandtheWesternImagination,1908–1918(1994,reissued1996),isabeautifullyillustratedstudyofthesocialandculturalimpactofearlyflight.

R.E.G.Davies,TheWorld’sAirlines(1964;alsopublishedasAHistoryoftheWorld’sAirlines,1964,reprinted1983),isanindispensableencyclopaedicreference.RogerE.Bilstein,FlightinAmerica:FromtheWrightstotheAstronauts,3rded.(2001),includessocialandculturalcommentaryonairlinetrendsaswellasdevelopmentsingeneralaviation.OliverE.Allenetal.,TheAirlineBuilders(1981),isasuperblyillustratedbookandacolourfulnarrativeaboutinternationalactivitiesduringthe1920sand’30s.TerryGwynn-Jones,FartherandFaster:Aviation’sAdventuringYears,1909–1939(1991),isanengrossingchronicleofrecordflightsandpersonalities.

WalterJ.BoyneandDonaldS.Lopez(eds.),TheJetAge:FortyYearsofJetAviation(1979),containsexcellentarticlesbytheprincipalengineersofthe

time.BillGunston,WorldEncyclopediaofAeroEngines,5thed.(2006),isanindispensablereferencethatchartstheprogressofallthemainenginecompanies.WalterJ.Boyne,ClashofWings(1994),isacomprehensiveoverviewofWorldWarIIaerialoperationsthatincludestheintroductionofjetaircraft.JohnD.Anderson,Jr.,AHistoryofAerodynamicsandItsImpactonFlyingMachines(1997),isacomprehensive,ifdemanding,historyofaerodynamics.BillGunston,Avionics(1990),containsanin-depthhistoryofthedevelopmentsofmodernavionics.DonaldM.Patillo,PushingtheEnvelope(1998),isanexcellentreviewoftheAmericanaircraftindustry,withinsightfulstatistics.

HELICOPTERS

BasicHelicopterHandbook,rev.ed.(1978),preparedbytheU.S.FederalAviationAdministration,isawell-illustratedprimerontheprinciplesofhelicopterflightandstructure.WalterJ.BoyneandDonaldS.Lopez(eds.),VerticalFlight:TheAgeoftheHelicopter(1984),surveysthehistoryandtechnologyofhelicoptersandotheraircraftdesignedforverticalflight.MikeRogers,VTOLMilitaryResearchAircraft(1989),describesbasictypesofresearchandproductionvertical-takeoffaircraft.

AIRPORTS

NormanAshfordandPaulH.Wright,AirportEngineering,3rded.(1992),comprehensivelysetsforththeplanning,layout,anddesignofpassengerandfreightairports,includingheliportsandshorttakeoffandlanding(STOL)facilities.RobertHoronjeffandFrancisX.McKelvey,PlanningandDesignofAirports,4thed.(1993),isacomprehensivecivilengineeringtextontheplanning,layout,anddesignofairportswithstrongemphasisonaspectssuchasaircraftpavementsanddrainage.ChristopherR.Blow,AirportTerminals,2nded.(1995),providesanarchitecturalviewofthefunctioningofairportpassengerterminalswithextensivecoverageofdesigncasestudies.

NormanAshford,H.P.MartinStanton,andCliftonA.Moore,AirportOperations,2nded.(1996),extensivelydiscussesmanyaspectsofairportoperationandmanagement,includingadministrativestructure,security,safety,environmentalimpact,performanceindices,andpassengerandaircrafthandling.NormanAshfordandCliftonA.Moore,AirportFinance,2nded.(1999),discussestherevenueandexpenditurepatternsofairportauthorities,methodsof

financing,businessplanning,andprojectappraisal.

INDEX

A

Abruzzo,BenL.,28Ader,Clément,41–42Aeroflot,71–72,79,92aeronauticalinfrastructure,68–69Airbus,94AirForceOne,96–98airlines,61–62,63–64thefirst,56–60postwar,71–74reequipmentof,89–92

airmail,60–61,62airplanesaviationpioneers,36,38–51famousearlyflights,53–56improvementsintechnology,61–69inventionof,36–51jetplanes,82–103problemofcontroland,36,46–48problemofliftand,36,37–40problemofpropulsionand,36,40–46WorldWarIIand,56,64,67,68,69–71

airports,69,123–144airfieldlighting,134airportsecurity,140–144

airtrafficcontrol,135–136cargofacilities,136–138environmentalimpact,138–140navigationalaids,133–134operationalrequirements,128runwayconfigurations,129–131runwaymarkings,134–135runwaypavements,131–133

airships,31–35,65typesof,31–32

airtrafficcontrol,135–136Alcock,John,53Allen,Bryan,120,121Amundsen,Roald,34Anderson,Maxie,28Anderson,Orville,13AntonovAN-2,79Aoki,Rocky,28Arban,Françoise,11Archimedes’principle,2,4Artingstall,F.D.,40autogiros,76–77,107,108avionics,98–100

B

Bacon,JohnM.,11balloonflight,1–17,18–31abouthot-airballoons,16–17,18–23

elementsof,2–4thefirst,1

gas-hot-airhybridballoons,1,8–9high-altitude/stratosphereballooning,1,12–13,14,18,23–27long-distance,27–31militaryexperiments/useand,11,16–17petroleumfueland,11–12pioneersof,4–8plasticballoons,13–15smokeandcoalgas,9–11superpressureballoons,9,15–16Barnes,Tracy,17,22Beaver,78–79Beechcraft,75,77,78Benz,Karl,42blackbox,the,86–88Blanchard,Jean-Pierre,27Blériot,Louis,49–50Boeing,63,64,65,67,73,85,89,90,91,92–93,94,96,97,98,100,131,139Borschberg,André,122Bothezat,Georgede,107Boyle’slaw,2Branson,Richard,28Breguet,LouisandJacques,106Brown,Arthur,53Browning,John,39Buseman,Adolph,88Byrd,Richard,54

C

Cavallo,Tiberius,4Cayley,George,38–39,46–47,82,106Cessna,75,77,78Chanute,Octave,39,116,117Charles,Jacques-Alexandre-César,2,6,7–8,23–24Charles’slaw,2Cierva,Juandela,107Clark,Ron,28Cobham,Alan,54cockpitvoicerecorder(CVR),86,87–88Comet,87,89–90Concorde,the,101,102Convair,71,90Cornu,Paul,106Curtiss,GlennHammond,49,51

D

Daimler,Gottlieb,42DanielGuggenheimFundforthePromotionofAeronautics,68–69DC-3,64–65,69,71,123,131DC-4,t21467–68,69DeHavilland,52,57,61,78,79–80,87,89–90,95DeHavilland,Geoffrey,57Douglas,63,65,67–68,71,72,73,77,89,90,93,123,131,139

E

Earhart,Amelia,56

Eckener,Hugo,34Ellehammer,Jacob,107Ellsworth,Lincoln,34Esnault-Pelterie,Robert,49–50

F

Farman,Henri,48–49,24159flightdatarecorder(FDR),86,87–88Fokker,Anthony,63Fossett,Steve,28,30–31Franz,Anselm,84

G

Gatty,Harold,54generalaviation,74–81Giffard,Henri,32GlobalPositioningSystem(GPS),4,99GrafZeppelin,34Green,Charles,9–11,27

H

Haenlein,Paul,32hanggliders,104,116–119Hargrave,Lawrence,40,82Heinkel,Ernst,83–84helicopters,76–77,94,104–116controlfunctions,115–116historyof,105–111

principlesofflightandoperation,111–115

Herring,Augustus,116Hindenburg,34,65disasterof,34,35,65

hot-airballoons,18–23baskets,23burners,22–23componentsof,19–23deflationsystems,21–22envelopedesign,19–21modern,16–17

Hughes,Howard,56

I

instrumentflightrule(IFR),129–130,131instrumentlandingsystem(ILS),133instrumentmeteorologicalconditions(IMC),133internal-combustionengine,32,40,42,104InternationalCivilAviationOrganization(ICAO),70,140–141,142

J

Jeffries,John,27jetage,82–103avionics,98–99firstexperiments,82–83passengersupportand,100progressinenginesandairframes,92–98

reequipmentofairlines,89–92safetyand,98–100technicaladvantagesandchallenges,84–89WorldWarIIand,83–84

Johnson,ThomasH.,14Jones,Brian,28,122Jones,RobertT.,88

K

Kittinger,JosephW.,28

L

Langley,SamuelPierpont,42,45Laurent,Françoise,5,7Lenoir,Étienne,42LeonardodaVinci,38,83,105–106Lilienthal,Otto,39,47,82,116,117Lindbergh,Charles,53–54,55,86–87Lindstrand,Per,28Lockheed,56,68,72,73,84,89,93,95

M

MacCready,Paul,120–122Mason,Thomas“Monck,”27Maxim,Hiram,41–42McDonnellDouglas,63,93Montgolfier,Jacques-Étienne,4–7Montgolfier,Joseph-Michel,4–7

Mozhaysky,Alexandr,41–42

N

NationalAdvisoryCommitteeforAeronautics(NACA),62–63,68,88Newman,LarryM.,20528Nobile,Umberto,34

O

Oehmichen,Étienne,107Ohain,HansJoachimPabstvon,82,83,84Otto,Nikolaus,42

P

passengersupportandthejetage,100Pavlecki,Vladimir,84Pénaud,Alphonse,47,106Phillips,Horatio,39Piasecki,Frank,109Piccard,Auguste,12–13,24,28Piccard,Bertrand,28,122Piccard,Donald,15,17,27,28Piccard,Jean,12,13–14,15,24PilâtredeRozier,Jean-Françoise,5,7,8–9Pilcher,Percy,47Piper,75,77,78Post,Wiley,54–56Prandtl,Ludwig,50Price,Nathan,84

Ptacek,Stephen,121

R

Reitsch,Hanna,108Richet,Charles,106Robert,Anne-Jean,7Robert,Marie-Noël,7–8Rogallo,FrancisandGertrude,117Ryan,JamesJ.,87

S

Santos-Dumont,Alberto,32,48,49security,airport,140–144Sikorsky,Igor,65,76,106,109SpiritofSt.Louis,55Stevens,Capt.A.,13Stringfellow,Frederick,40Stringfellow,John,82supersonicflight,100–103

T

Taylor,Charles,43terroristattacksandairplanes,141–144Tissandier,AlbertandGaston,32Tupolev,91,101–103turbofanengine,92

U

ultralights,104,119–122U.S.ArmyAirForceAirTransportCommand(ATC),70utilityaviation,74–75,77

V

visualflightrules(VFR),129,130visualmeteorologicalconditions(VMC),133Voisin,Gabriel,48,49

W

Warren,David,87Warsitz,Erich,84Wenham,FrancisH.,38–39Whittle,Frank,82,83,84Wise,John,11,21Woelfert,Karl,42WorldWarI,andairplanes,50,52,53,60,61WorldWarIIairplanesand,56,64,67,68,69–71,83airshipsand,35ballooningafter,14jetageand,83–84

Wright,Orville,36,39–40,42–46,47,48,49,55,82,86,106,117Wright,Wilbur,36,39–40,42–46,47,48,49,55,82,86,106,117

Y

Yeager,CharlesE.,101Yost,Paul“Ed,”16,17,27,28

Young,Arthur,109

Z

Zeppelin,Ferdinand,Countvon,32–34,35zeppelins,32–34,35