Whileat12milesthesustainingpowerisfiguredat230pounds，at24milesitisfourtimesasgreat，or920
pounds.
SupportingAreaofBirds.
Oneofthethingswhichallproducingaviatorsseektocopyisthemotivepowerofbirds，particularlyintheirrelationtotheareaofsupport.Closeinvestigationhasestablishedthefactthatthelargerthebirdthelessistherelativeareaofsupportrequiredtosecureagivenresult.Thisisshowninthefollowingtable：
SupportingWeightSurfaceHorseareaBirdinlbs.insq.feetpowerperlb.
Pigeon1.000.70.0120.7
WildGoose9.002.650.0260.2833
Buzzard5.005.030.0151.06
Condor17.009.850.0430.57
Sofarasknownthecondoristhelargestofmodernbirds.Ithasawingstretchof10feetfromtiptotip，asupportingareaofabout10squarefeet，andweighs17
pounds.It.iscapableofexertingperhaps1—30horsepower.
（Thesefiguresare，ofcourse，approximate.）
Comparingthecondorwiththebuzzardwithawingstretchof6feet，supportingareaof5squarefeet，andalittleover1—100horsepower，itmaybeseenthat，broadlyspeaking，thelargerthebirdthelesssurfacearea（relatively）
isneededforitssupportintheair.
ComparisonWithAeroplanes.
Ifwecomparethebirdfigureswiththosemadepossiblebythedevelopmentoftheaeroplaneitwillbereadilyseenthatmanhasmadeawonderfuladvanceinimitatingtheresultsproducedbynature.Herearethefigures：
SupportingWeightSurfaceHorseareaMachineinlbs.insq.feetpowerperlb.
Santos—Dumont350110.00300.314
Bleriot700150.00250.214
Antoinette1，200538.00500.448
Curtiss700258.00600.368
Wright[4]1，100538.00250.489
Farman1，200430.00500.358
Voisin1，200538.00500.448
[4]TheWrights’newmachineweighsonly900pounds.
Whiletheaveragesupportingsurfaceisinfavoroftheaeroplane，thisismorethanoverbalancedbythegreateramountofhorsepowerrequiredfortheweightlifted.Theaveragesupportingsurfaceinbirdsisaboutthree—quartersofasquarefootperpound.Intheaverageaeroplaneitisaboutone—halfsquarefootperpound.
Ontheotherhandtheaverageaeroplanehasaliftingcapacityof24poundsperhorsepower，whilethebuzzard，forinstance，lifts5poundswith15—100ofahorsepower.
IftheWrightmachine——whichhasaliftingpowerof50
poundsperhorsepower——shouldbealoneconsideredtheshowingwouldbemuchmorefavorabletotheaeroplane，butitwouldnotbeafaircomparison.
MoreSurface，LessPower.
Broadlyspeaking，thelargerthesupportingareathelesswillbethepowerrequired.Wright，bytheuseof538squarefeetofsupportingsurface，getsalongwithanengineof25horsepower.Curtiss，whousesonly258
squarefeetofsurface，findsanengineof50horsepowerisneeded.Otherthings，suchasframe，etc.，beingequal，itstandstoreasonthatareductionintheareaofsupportingsurfacewillcorrespondinglyreducetheweightofthemachine.ThuswehavetheCurtissmachinewithits258squarefeetofsurface，weighingonly600pounds（withoutoperator），butrequiringdoublethehorsepoweroftheWrightmachinewith538squarefeetofsurfaceandweighing1，100pounds.Thisdemonstratesinaforcefulwaythepropositionthatthelargerthesurfacethelesspowerwillbeneeded.
Butthereisalimit，onaccountofitsbulkandawkwardnessinhandling，beyondwhichthesurfaceareacannotbeenlarged.Otherwiseitmightbepossibletoequipandoperateaeroplanessatisfactorilywithenginesof15horsepower，orevenless.
TheFuelConsumptionProblem.
Fuelconsumptionisaprimefactorintheproductionofenginepower.Theveriestmechanicaltyroknowsinageneralwaythatthemorepowerissecuredthemorefuelmustbeconsumed，allowingthatthereisnodifferenceinthepower—producingqualitiesofthematerialused.Butfewofusunderstandjustwhattheratioofincreaseis，orhowitiscaused.Thispropositionisoneofkeeninterestinconnectionwithaviation.
Letusciteaproblemwhichwillillustratethepointquoted：Allowingthatittakesagivenamountofgasolenetopropelaflyingmachineagivendistance，halfthewaywiththewind，andhalfagainstit，thewindblowingatone—halfthespeedofthemachine，whatwillbetheincreaseinfuelconsumption？
IncreaseofThirtyPerCent.
Onthefaceofittherewouldseemtobenocallforanincreaseastheresistancemetwhengoingagainstthewindisapparentlyoffsetbythepropulsiveforceofthewindwhenthemachineistravellingwithit.This，however，iscalledfaultyreasoning.Theincreaseinfuelconsumption，asfiguredbyMr.F.W.Lanchester，oftheRoyalSocietyofArts，willbefully30percentovertheamountrequiredforasimilaroperationofthemachineinstillair.Ifthejourneyshouldbemadeatrightanglestothewindunderthesameconditionstheincreasewouldbe15percent.
InotherwordsMr.Lanchestermaintainsthattheworkdonebythemotorinmakingheadwayagainstthewindforacertaindistancecallsformoreengineenergy，andconsequentlymorefuelby30percent，thanissavedbythehelpingforceofthewindonthereturnjourney.
CHAPTERXIV.
ABOUTWINDCURRENTS，ETC.
Oneofthefirstdifficultieswhichthenovicewillencounteristheuncertaintyofthewindcurrents.Withalowvelocitythewind，somedistanceawayfromtheground，isordinarilysteady.Asthevelocityincreases，however，thewindgenerallybecomesgustyandfitfulinitsaction.This，itshouldberemembered，doesnotrefertothevelocityofthemachine，buttothatoftheairitself.
InthisconnectionMr.ArthurT.Atherholt，presidentoftheAeroClubofPennsylvania，inaddressingtheBostonSocietyofScientificResearch，said：
\"ProbablythewhirlpoolsofNiagaracontainnomoreerraticcurrentsthanthestrataofairwhichisnowimmediatelyaboveus，afacthardtorealizeonaccountofitsinvisibility.\"
ChangesInWindCurrents.
WhileMr.Atherholt’sexperiencehasbeenmainlywithballoonsitisallthemorevaluableonthisaccount，astheballoonswereatthemercyofthewindandtheirvaryingdirectionsaffordedanindisputableguideastothechangingcourseoftheaircurrents.Inspeakingofthishesaid：
\"Inthemanytripstaken，varyingindistancetraversedfromtwenty—fiveto900miles，itwasneverpossibleexceptinoneinstancetomaintainastraightcourse.
TheseuncertaincurrentsweremostnoticeableintheGordon—BennettracefromSt.Louisin1907.Ofthenineaerostatscompetinginthatevent，eightcoveredamoreorlessdirectcoursedueeastandsoutheast，whereasthewriter，withMajorHenryB.Hersey，firststartednorthwest，thennorth，northeast，east，eastbysouth，andwhenoverthecenterofLakeEriewereagainblownnorthwestnotwithstandingthatmorefavorablewindsweresoughtforataltitudesvaryingfrom100to3，000
meters，necessitatingafinishinCanadanearlynortheastofthestartingpoint.
\"Thesenineballoons，makinglandingsextendingfromLakeOntario，Canada，toVirginia，allstartedfromonepointwithinthesamehour.
\"ThesingleexceptiontotheserovingcurrentsoccurredonOctober21st，oflastyear（1909）when，startingfromPhiladelphia，thewindshiftedmorethaneightdegrees，thegreatestvariationbeingatthelowestaltitudes，yetatnotimewasaheightofoveramilereached.
\"Throughouttheentiredaytheskywasovercast，withathermometervaryingfromfifty—sevendegreesat300
feettoforty—fourdegrees，Fahrenheitat5，000feet，atwhichaltitudethewindhadavelocityof43milesanhour，incloudsofacirro—cumulusnature，alandingfinallybeingmadenearTannersville，NewYork，intheCatskillmountains，afteravoyageoffiveandone—halfhours.
\"Ihavenoknowledgeofarecordedtripofthisdistanceandduration，maintainedinpracticallyastraightlinefromstarttofinish.\"
Thiswinddisturbanceismorenoticeableandmoredifficulttocontendwithinaballoonthaninaflyingmachine，owingtothebulkandunwieldycharacteroftheformer.Atthesametimeitisnotconducivetopleasant，safeorsatisfactorysky—sailinginanaeroplane.
Thisisnotstatedwiththepurposeofdiscouragingaviation，butmerelythattheoperatormayknowwhattoexpectandbepreparedtomeetit.
Notonlydoesthewindchangeitshorizontalcourseabruptlyandwithoutnotice，butitalsoshiftsinaverticaldirection，onesecondblowingup，andanotherdown.Nomanhasasyetfathomedthewhyandwhereforeofthiserraticaction;itisonlyknownthatitexists.
Themoststablecurrentswillbefoundfrom50to100
feetfromtheearth，providedthewindisnotdivertedbysuchobjectsastrees，rocks，etc.Thatthereareequallystablecurrentshigherupistrue，buttheyaregenerallytobefoundatexcessivealtitudes.
HowaBirdMeetsCurrents.
Observeabirdinactiononawindydayandyouwillfinditcontinuallychangingthepositionofitswings.
Thisisdonetomeetthevaryinggustsandeddiesoftheairsothatsustentationmaybemaintainedandheadwaymade.Onesecondthebirdisbendingitswings，alteringtheangleofincidence;thenextitisliftingordepressingonewingatatime.Stillagainitwillextendonewingtipinadvanceoftheother，orbespreadingorfolding，loweringorraisingitstail.
Allthesemotionshaveameaning，apurpose.Theyassistthebirdinpreservingitsequilibrium.Withoutthemthebirdwouldbejustashelplessintheairasahumanbeingandcouldnotremainafloat.
Whenthewindisstill，orcomparativelyso，abird，havingsecuredthedesiredaltitudebyflightatanangle，maysailorsoarwithnowingactionbeyondanoccasionalstrokewhenitdesirestoadvance.But，inagusty，uncertainwinditmustuseitswingsoralightsomewhere.
TryingtoImitatetheBird.
Writingin_Fly_，Mr.WilliamE.Whitesays：
\"Thebird’sflightsuggestsanumberofwaysinwhichtheequilibriumofamechanicalbirdmaybecontrolled.
Eachofthesemethodsofcontrolmaybeeffectedbyseveraldifferentformsofmechanism.
\"Placingthetwowingsofanaeroplaneatanangleofthreetofivedegreestoeachotherisperhapstheoldestwayofsecuringlateralbalance.Thiswayreadilyoccurstoanyonewhowatchesaseagullsoaring.Thetheoryofthedihedralangleisthatwhenonewingisliftedbyagustofwind，theairisspilledfromunderit;
whiletheotherwing，beingcorrespondinglydepressed，presentsagreaterresistancetothegustandisliftedrestoringthebalance.Afixedangleofthreetofivedegrees，however，willonlybesufficientforverylightpuffsofwindandtomountthewingssothatthewholewingmaybemovedtochangethedihedralanglepresentsmechanicaldifficultieswhichwouldbebetteravoided.
\"Theobjectionofmechanicalimpracticabilityappliestoanyplantopreservethebalancebyshiftingweightorballast.Thecenterofgravityshouldbelowerthanthecenterofthesupportingsurfaces，butcannotbemademuchlower.Itisacommonmistaketoassumethatcompletestabilitywillbesecuredbyhangingthecenterofgravityverylowontheprincipleoftheparachute.Anaeroplanedependsuponrapidhorizontalmotionforitssupport，andifthecenterofgravitybefarbelowthecenterofsupport，everychangeofspeedorwindpressurewillcausethemachinetoturnaboutitscenterofgravity，pitchingforwardandbackwarddangerously.
PreservingLongitudinalBalance.
\"Thebirdsmaintainlongitudinal，orforeandaftbalance，byelevatingordepressingtheirtails.Whetherthisactionissecuredinanaeroplanebymeansofahorizontalrudderplacedintherear，orbydeflectingplanesplacedinfrontofthemainplanes，theprincipleisevidentlythesame.AhorizontalrudderplacedwelltotherearasintheAntoinette，BleriotorSantos—Dumontmonoplanes，willbeverymuchsaferandsteadierthanthedeflectingplanesinfront，asintheWrightorCurtissbiplanes，butnotsosensitiveorpromptinaction.
\"Thenaturalforeandaftstabilityisverymuchstrengthenedbyplacingtheloadwellforward.Thecenterofgravitynearthefrontandatailorrudderstreamingtotherearsecuresstabilityasanarrowisbalancedbytheheadandfeathering.Theadoptionofthisprinciplemakesitalmostimpossiblefortheaeroplanetoturnover.
TheMatterofLateralBalance.
\"Allsuccessfulaeroplanesthusfarhavemaintainedlateralbalancebytheprincipleofchangingtheangleofincidenceofthewings.
\"Otherwaysofmaintainingthelateralbalance，suggestedbyobservationoftheflightofbirdsare——extendingthewingtipsandspillingtheairthroughthepinions;
or，whatisthesamething，varyingtheareaofthewingsattheirextremities.
\"Extendingthewingtipsseemstobeasimpleandeffectivesolutionoftheproblem.Thetipsmaybemadetoswingoutwarduponaverticalaxisplacedatthefrontedgeofthemainplanes;ortheymaybehingedtotheendsofthemainplanesoastobeelevatedordepressedthroughsuitableconnectionsbytheaviator;ortheymaybesupportedfromahorizontalaxisparallelwiththeendsofthemainplanessothattheymayswingoutward，theaviatorcontrollingbothtipsthroughoneleversothatasonetipisextendedtheotherisretracted.
\"Theelasticwingpinionsofabirdbendeasilybeforethewind，permittingtheguststoglanceoff，butpresentingalwaysanevenandefficientcurvaturetothesteadycurrentsoftheair.\"
HighWindsThreatenStability.
Toensureperfectstability，withoutcontrol，eitherhumanorautomatic，itisassertedthattheaeroplanemustmovefasterthanthewindisblowing.Solongasthewindisblowingattherateof30milesanhour，andthemachineistraveling40ormore，therewillbelittletroubleasregardsequilibriumsofaraswinddisturbancegoes，providedthewindblowsevenlyanddoesnotcomeingustsoreddyingcurrents.Butwhenconditionsarereversed——whenthemachinetravelsonly30milesanhourandthewindblowsattherateof50，lookoutforlossofequilibrium.
Oneofthemainreasonsforthisisthathighwindsarerarelysteady;theyseldomblowforanylengthoftimeatthesamespeed.Theyareusually\"gusty，\"thegustsbeingamomentarymovementatahigherspeed.
Tornadicgustsarealsoformedbythemeetingoftwoopposingcurrents，causingawhirlingmotion，whichmakesstabilityuncertain.Besides，itisnotunusualforwindofhighspeedtosuddenlychangeitsdirectionwithoutwarning.
TroubleWithVerticalColumns.
Verticalcurrents——columnsofascendingair——arefrequentlyencounteredinunexpectedplacesandhavemoreorlesstendency，accordingtotheirstrength，tomakeitdifficulttokeepthemachinewithinareasonabledistancefromtheground.
Theseverticalcurrentsaremostgenerallynoticeableinthevicinityofsteepcliffs，ordeepravines.Insuchinstancestheyareusuallyofconsiderablestrength，beingcausedbythedeflectionofstrongwindsblowingagainstthefaceofthecliffs.Thisdeflectionexertsabackpressurewhichisfeltquiteadistanceawayfromthepointoforigin，sothattheverticalcurrentexertsaninfluenceinforcingthemachineupwardlongbeforethecliffisreached.
CHAPTERXV.
THEELEMENTOFDANGER.
Thatthereisanelementofdangerinaviationisundeniable，butitisnowheresogreatasthepublicimagines.Menarekilledandinjuredintheoperationofflyingmachinesjustastheyarekilledandinjuredintheoperationofrailways.Consideringthecharacterofaviationthepercentageofcasualtiesissurprisinglysmall.
Thisisbecausetheresultsfollowingacollapseintheairareverymuchdifferentfromwhatmightbeimagined.
Insteadofdroppingtothegroundlikeabulletanaeroplane，underordinaryconditionswill，whenanythinggoeswrong，sailgentlydownwardlikeaparachute，particularlyiftheoperatoriscool—headedandnervyenoughtosomanipulatetheapparatusastopreserveitsequilibriumandkeepthemachineonanevenkeel.
TwoFieldsofSafety.
Atleastoneprominentaviatorhasdeclaredthattherearetwofieldsofsafety——oneclosetotheground，andtheotherwellupintheair.Inthefirst—namedthefallwillbeaslightonewithlittlechanceoftheoperatorbeingseriouslyhurt.Fromthefieldofhighaltitudethethedescentwillbegradual，asarule，theplanesofthemachineservingtobreaktheforceofthefall.Withacool—headedoperatorincontroltheaeroplanemaybeevenguidedatanangle（about1to8）initsdescentsoastotouchthegroundwithaglidingmotionandwithaminimumofimpact.
Suchanexperience，ofcourse，isfarfrompleasant，butitisbynomeanssodangerousasmightappear.
Thereismorerealdangerinfallingfromanelevationof75or100feetthanthereisfrom1，000feet，asintheformercasethereisnochanceforthemachinetoserveasaparachute——itscontactwiththegroundcomestooquickly.
LessoninRecentAccidents.
AmongthemorerecentfatalitiesinaviationarethedeathsofAntonioFernandezandLeonDelagrange.Theformerwasthrowntothegroundbyasuddenstoppageofhismotor，theentiremachineseemingtocollapse.
Itisevidenttherewereradicaldefects，notonlyinthemotor，butintheaeroplaneframeworkaswell.AtthetimeofthestoppageitisestimatedthatFernandezwasupabout1，500feet，butthemachinegotnoopportunitytoexertaparachuteeffect，asitbrokeupimmediately.
Thiswouldindicateafatalweaknessinthestructurewhich，underpropertesting，couldprobablyhavebeendetectedbeforeitwasusedinflight.
Itishardtosayit，butDelagrangeappearstohavebeenculpabletogreatdegreeinoverloadinghismachinewithamotorequipmentmuchheavierthanitwasdesignedtosustain.Hewas65feetupintheairwhenthecollapseoccurred，resultinginhisdeath.AsinthecaseofFernandezcommon—senseprecautionwoulddoubtlesshavepreventedthefatality.
AviationNotExtraHazardous.
Alltoldtherehavebeen，uptothetimeofthiswriting（April，1910），justfivefatalitiesinthehistoryofpower—
drivenaviation.Thisissurprisinglylowwhenthenatureoftheexperiments，andthefactthatmostoftheoperatorswerefarfromhavingextendedexperience，istakenintoconsideration.MenliketheWrights，Curtiss，Bleriot，Farman，Paulhanandothers，arenowexperts，buttherewasatime，anditwasnotlongago，whentheywereunskilled.Thatthey，withnumerousotherslesswidelyknown，shouldhavecomesafelythroughtheirmanyexperimentswouldseemtodisprovetheprevailingideathataviationisanextrahazardouspursuit.
Inthehandsofcareful，quick—witted，nervymenthesailingofanairshipshouldbenomorehazardousthanthesailingofayacht.Avesselcaptainwithcommonsensewillnotgotoseainastorm，ornavigateaweak，unseaworthycraft.Neithershouldanaviatorattempttosailwhenthewindishighandgusty，norwithamachinewhichhasnotbeenthoroughlytestedandfoundtobestrongandsafe.
SaferThanRailroading.
Statisticsshowthatsome12，000peoplearekilledand72，000injuredeveryyearontherailroadsoftheUnitedStates.Cometothinkitoveritissmallwonderthatthelistoffatalitiesissolarge.Trainsarerunathighspeeds，dashingovercrossingsatwhichcollisionsareliabletooccur，andoverbridgeswhichoftencollapseoraresweptawaybyfloods.Still，whilethenumberofcasualtiesislarge，theactualpercentageissmallconsideringtheimmensenumberofpeopleinvolved.
Itissoinaviation.Thenumberofcasualtiesisremarkablysmallincomparisonwiththenumberofflightsmade.Inthehandsofcompetentmenthesailingofanairshipshouldbe，andis，freerfromriskofaccidentthantherunningofarailwaytrain.Therearenorailstospreadorbreak，nobridgestocollapse，nocrossingsatwhichcollisionsmayoccur，nochanceforsomesleepyoroverworkedemployeetomisunderstandthedispatcher’sordersandcauseawreck.
TwoMainCausesofTrouble.
Thetwomaincausesoftroubleinanairshipleadingtodisastermaybeattributedtothestoppageofthemotor，andtheaviatorbecomingrattledsothathelosescontrolofhismachine.Moderningenuityisfastdevelopingmotorsthatalmostdailybecomemoreandmorereliable，andexperienceismakingaviatorsmoreandmoreself—confidentintheirabilitytoactwiselyandpromptlyincasesofemergency.Besidesthisasatisfactorysystemofautomaticcontrolisinafairwayofbeingperfected.
Occasionallyeventhemostexperiencedandcompetentofmeninallcallingsbecomecarelessandbyfoolishactioninvitedisaster.Thisistrueofaviatorsthesameasitisofrailroaders，menwhoworkindynamitemills，etc.Butinnearlyeveryinstancetheresponsibilityrestswiththeindividual;notwiththesystem.Therearesomemenunfittedbynatureforaviation，justasthereareothersunfittedtoberailwayengineers.
CHAPTERXVI.
RADICALCHANGESBEINGMADE.
Changes，manyofthemextremelyradicalintheirnature，arecontinuallybeingmadebyprominentaviators，andparticularlythosewhohavewonthegreatestamountofsuccess.Wonderfulastheresultshavebeenfewoftheaviatorsarereallysatisfied.Theirsuccesseshavemerelyspurredthemontonewendeavors，theultimateendbeingthedevelopmentofanabsolutelyperfectaircraft.
AmongthemenwhohavebeenthusexperimentingaretheWrightBrothers，wholastyear（1909）broughtoutacrafttotallydifferentasregardsproportionsandweightfromtheoneusedtheprecedingyear.Onemarkedresultwasagainofabout31/2milesanhourinspeed.
Dimensionsof1908Machine.
The1908modelaeroplanewas40by29feetoverall.
Thecarryingsurfaces，thatis，thetwoaerocurves，were40by6feet，havingaparabolicalcurveofoneintwelve.
Withabout70squarefeetofsurfaceintherudders，thetotalsurfacegivenwasabout550squarefeet.Theengine，whichistheinventionoftheWrightbrothers，weighed，approximately，200pounds，andgaveabout25
horsepowerat1，400revolutionsperminute.Thetotalweightoftheaeroplane，exclusiveofpassenger，butinclusiveofengine，wasabout1，150pounds.Thisresultshowedaliftofafractionover21/4poundstothesquarefootofcarryingsurface.Thespeeddesiredwas40
milesanhour，butthemachinewasfoundtomakeonlyascant39milesanhour.Theuprightstrutswereabout7/8—inchthick，theskids，21/2by11/4inchesthick.
Dimensionsof1909Machine.
The1909aeroplanewasbuiltprimarilyforgreaterspeed，andrelativelyheavier;tobelessatthemercyofthewind.Thisresultwasobtainedasfollows：Theaerocurves，orcarryingsurfaces，werereducedindimensionsfrom40by6feetto36by51/2feet，thecurveremainingthesame，oneintwelve.Theuprightstrutswerecutfromseven—eighthsinchtofive—eighthsinch，andtheskidsfromtwoandone—halfbyoneandone—quartertotwoandone—quarterbyoneandthree—eighthsinches.
Thisresultshowsthatthereweresome81squarefeetofcarryingsurfacemissingoverthatoflastyear’smodel.andsome25poundslossofweight.Relatively，though，the1909modelaeroplane，whileactually25
poundslighter，isreallysome150poundsheavierintheairthanthe1908model，owingtothelessersquarefeetofcarryingsurface.
SomeoftheResultsObtained.
Reducingthecarryingsurfacesfrom6to51/2feetgavetworesults——first，lesscarryingcapacity;and，second，lesshead—onresistance，owingtothefactthattheextentoftheparaboliccurveinthecarryingsurfaceswasshortened.The\"head—on\"resistanceistheretardancetheaeroplanemeetsinpassingthroughtheair，andiscountedinsquarefeet.Inthe1908modelthecurvebeingoneintwelveand6feetdeep，gave6inchesofhead—onresistance.Theplanebeing40feetspread，gave6inchesby40feet，or20squarefeetofhead—onresistance.Increasingthisfigurebyalikeamountforeachplane，andaddingapproximately10squarefeetforstruts，skidsandwiring，wehaveatotalofapproximately，50squarefeetofsurfacefor\"head—on\"resistance.
Inthe1909aeroplane，shorteningthecurve6inchesattheparabolicendofthecurvetookoff1inchofhead—onresistance.Shorteningthespreadoftheplanestookoffbetween3and4squarefeetofhead—onresistance.
Addtothisthetotalof7squarefeet，lesscurvesurfaceandabout1squarefoot，lesswireandwoodworkresistance，andwehaveagrandtotalof，approximately，12squarefeetofless\"head—on\"resistanceoverthe1908model.
ChangesinEngineAction.
Theengineusedin1909wasthesameoneusedin1908，thoughsomeminorchangesweremadeasimprovements;forinstance，amakeandbreaksparkwasused，andanine—tooth，insteadofaten—toothmagnetogear—wheelwasused.Thisincreasedtheenginerevolutionsperminutefrom1，200to1，400，andthepropellerrevolutionsperminutefrom350to371，givingapropellerthrustof，approximately，170footpoundsinsteadof153，aswashadlastyear.
MoreSpeedandSameCapacity.
Oneunsatisfactoryfeatureofthe1909modeloverthatof1908，apparently，wasthelackofinherentlateralstability.Thiswascausedbythelessersurfaceandlesserextentofcurvaturesattheportionsoftheaeroplanewhichwerewarped.ThisdefectdidnotshowsoplainlyafterMr.OrvilleWrighthadbecomefullyproficientinthehandlingofthenewmachine，andwithskillfulmanagement，the1909modelaeroplanewillbejustassafeandsecureastheotherthoughitwilltakealittlemorepracticetogetthatsamedegreeofskill.
Tosumup：Theaeroplaneusedin1909was25
poundslighter，butreallyabout150poundsheavierintheair，hadlesshead—onresistance，andgreaterpropellerthrust.Thespeedwasincreasedfromabout39
milesperhourto421/2milesperhour.Theliftingcapacityremainedaboutthesame，about450poundscapacitypassenger—weight，withthe1908machine.Inthisrespect，thelossofcarryingsurfacewascompensatedforbytheincreasedspeed.
Duringthefirstfewflightsitwasplainlydemonstratedthatitwouldneedthehighestskilltoproperlyhandletheaeroplane，asfirstoneendandthentheotherwoulddipandstriketheground，andeithertearthecanvasorslewtheaeroplanearoundandbreakaskid.
WrightsAdoptWheeledGears.
InstillanotherimportantrespecttheWrights，sofarastheoutputofoneoftheircompaniesgoes，havemadearadicalchange.AlltheaeroplanesturnedoutbytheDeutschWrightGesellschaft，accordingtotheGermanpublication，_Automobil—Welt_，willhereafterbeequippedwithwheeledrunninggearsandtails.Theplanofthisnewmachineisshownintheillustrationonpage145.
Thewheelsarethreeinnumber，andareattachedonetoeachofthetwoskids，justunderthefrontedgeoftheplanes，andoneforwardofthese，attachedtoacross—
member.Itisassertedthatwiththesewheelstheteachingofpurchaserstooperatethemachinesismuchsimplified，asthebeginnerscanmakeshortflightsontheirownaccountwithoutusingthestartingderrick.
ThisisabigconcessionfortheWrightstomake，astheyhavehithertoadheredstoutlytotheskidgear.
WhileitistruetheydonotcontroltheGermancompanyproducingtheiraeroplanes，yetthenatureoftheirconnectionwiththeenterpriseissuchthatitmaybetakenforgrantednoradicalchangesinconstructionwouldbemadewithouttheirapprovalandconsent.
OnlyThreeDangerousRivals.
Officialtrialswiththe1909modelsmashedmanyrecordsandleavetheWrightbrotherswithonlythreedangerousrivalsinthefield，andwithbasicpatentswhichcoverthecurve，warpandwing—tipdevicesfoundonalltheothermakesofaeroplanes.ThesethreerivalsaretheCurtissandVoisinbiplanetypeandtheBleriotmonoplanepattern.
TheBleriotmonoplaneisprobablythemostdangerousrival，asthismakeofmachinehasarecordof54
milesperhour，hascrossedtheEnglishchannel，andhasliftedtwopassengersbesidestheoperator.Thelatesttypeofthismachineonlyweighs771.61poundscomplete，withoutpassengers，andwillliftatotalpassengerweightof462.97pounds，whichisaliftof5.21poundstothesquarefoot.ThisisabetterresultthanthosepublishedbytheWrightbrothers，thebestnotedbeing4.25poundspersquarefoot.
OtherAviatorsatWork.
TheWrights，however，arenotaloneintheireffortstopromotetheefficiencyoftheflyingmachine.Othercompetentinventiveaviators，notablyCurtiss，Voisin，BleriotandFarman，arecloseafterthem.TheWrights，asstated，haveamarkedadvantageinthepossessionofpatentscoveringsurfaceplanedeviceswhichhavethusfarbeenfoundindispensableinflyingmachineconstruction.
Numerouslawsuitsgrowingoutofallegedinfringementsofthesepatentshavebeenstarted，andothersarethreatened.Whateffecttheseactionswillhaveindeterringaviatorsingeneralfromproceedingwiththeirexperimentsremainstobeseen.
Inthemeantimethefourmennamed——Curtiss，Voisin，BleriotandFarman——aregoingaheadregardlessofconsequences，andtheinventivegeniusofeachissostrongthatitisreasonabletoexpectsomeremarkabledevelopmentsinthenearfuture.
SmallestofFlyingMachines.
ToSantosDumontmustbegiventhecreditofproducingthesmallestpracticalflyingmachineyetconstructed.
True，hehasdonenothingremarkablewithitinthelineofspeed，buthehasdemonstratedthefactthatalargesupportingsurfaceisnotanessentialfeature.
Thismachineisnamed\"LaDemoiselle.\"Itisamonoplaneofthedihedraltype，withamainplaneoneachsideofthecenter.Thesemainplanesareof18footspread，andnearly61/2feetindepth，givingapproximately115feetofsurfacearea.Thetotalweightis242pounds，whichis358poundslessthananyothermachinewhichhasbeensuccessfullyused.Thetotaldepthfromfronttorearis26feet.
Theframeworkisofbamboo，strengthenedandheldtautwithwireguys.
HaveOneRuleinMind.
Inthisstruggleformasteryinflyingmachineefficiencyallthecontestantskeeponeruleinmind，andthisis：
\"Thecarryingcapacityofanaeroplaneisgovernedbytheperipheralcurveofitscarryingsurfaces，plusthespeed;andthespeedisgovernedbythethrustofthepropellers，lessthe’head—on’resistance.\"
Theirideasastothepropermeansofapproachingthepropositionmay，andundoubtedlyare，atvariance，buttheoneruleinsolvingtheproblemofobtainingthegreatestcarryingcapacitycombinedwiththegreatestspeed，obtainsinallinstances.
CHAPTERXVII.
SOMEOFTHENEWDESIGNS.
Spurredonbythesuccessattainedbythemoreexperiencedandbetterknownaviatorsnumerousinventorsoflesserfamearealmostdailyproducingpracticalflyingmachinesvaryingradicallyinconstructionfromthosenowingeneraluse.
OneofthesecomparativelynewdesignsistheVanAndenbiplane，madebyFrankVanAndenofIslip，LongIsland，amemberoftheNewYorkAeronauticSociety.Whilehismachineiswhollyexperimental，manysuccessfulshortflightsweremadewithitlastfall（1909）.Oneflight，madeOctober19th，1909，isofparticularinterestasshowingthepracticabilityofanautomaticstabilizingdeviceinstalledbytheinventor.Themachinewascaughtinasuddenseveregustofwindandkeeledover，butalmostimmediatelyrighteditself，thusdemonstratinginamostsatisfactorymannerthevalueofonenewattachment.
FeaturesofVanAndenModel.
Insizethesurfacesofthemainbiplaneare26feetinspread，and4feetindepthfromfronttorear.Theupperandlowerplanesare4feetapart.Silkolenecoatedwithvarnishisusedforthecoverings.Ribs（spruce）arecurvedoneinchtothefoot，thedeepestpartofthecurve（4inches）beingonefootbackfromthefrontedgeofthehorizontalbeam.Struts（alsoofspruce，asisalltheframework）areellipticalinshape.
Themainbeamsareinthreesections，nearlyhalfroundinform，andjoinedbymetalsleeves.
Thereisatwo—surfacehorizontalrudder，2x2x4feet，infront.Thisispivotedatitslateralcenter8feetfromthefrontedgeofthemainplanes.Intherearisanothertwo—surfacehorizontalrudder2x2x21/2feet，pivotedinthesamemannerasthefrontone，15feetfromtherearedgesofthemainplanes.
Hingedtotherearcentralstrutoftherearrudderisaverticalrudder2feethighby3feetinlength.
TheMethodofControl.
Intheoperationoftheserudders——bothfrontandrear——andtheelevationanddepressionofthemainplanes，theCurtisssystemisemployed.Pushingthesteering—
wheelpostoutwarddepressesthefrontedgesoftheplanes，andbringsthemachinedownward;pullingthesteering—wheelpostinwardelevatesthefrontedgesoftheplanesandcausesthemachinetoascend.
Turningthesteeringwheelitselftotherightswingsthetailruddertotheleft，andthemachine，obeyingthislikeaboat，turnsinthesamedirectionasthewheelisturned.Bylikecauseturningthewheeltotheleftturnsthemachinetotheleft.
AutomaticControlofWings.
Therearetwowingtips，eachof6feetspread（length）
and2feetfromfronttorear.Thesearehingedhalfwaybetweenthemainsurfacestothetwooutermostrearstruts.Cablesrunfromthesetoanautomaticdeviceworkingwithpowerfromtheengine，whichautomaticallyoperatesthetipswiththetiltingofthemachine.Normallythewingtipsareheldhorizontalbystiffspringsintroducedinthecablesoutsideofthedevice.
ItwasthesuccessfulworkingofthisdevicewhichrightedtheVanAndencraftwhenitwasoverturnedinthesquallofOctober19th，1909.PrevioustothatoccurrenceMr.VanAndenhadlookeduponthedeviceaspurelyexperimental，andhadadmittedthathehadgraveuncertaintyastohowitwouldoperateintimeofemergency.Heisnowquotedasbeingthoroughlysatisfiedwithitspracticability.ItisthisautomaticdevicewhichgivestheVanAndenmachineatleastonedistinctivelynewfeature.
WhileonthissubjectitwillnotbeamisstoaddthatMr.Curtissdoesnotlookkindlyonautomaticcontrol.
\"Iwouldrathertrusttomyownactionthanthatofamachine，\"hesays.ThisisundoubtedlygoodlogicsofarasMr.Curtissisconcerned，butallaviatorsarenotsocool—headedandresourceful.
MotivePowerofVanAnden.
A50—horsepower\"H—F\"watercooledmotordrivesalaminatedwoodpropeller6feetindiameter，witha17
degreepitchattheextremities，increasingtowardthehub.Therearendofthemotorisabout6inchesbackfromthereartransversebeamandtheengineshaftisinadirectlinewiththeaxesofthetwohorizontalrudders.
AnR.I.V.ballbearingcarriestheshaftatthispoint.Flying，themotorturnsatabout800revolutionsperminute，delivering180poundspull.Atestofthemotorrunningat1，200showedapullof250poundsonthescales.
StillAnotherNewAeroplane.
AnothernewaeroplaneisthatproducedbyA.M.
Herring（anold—timer）andW.S.Burgess，underthenameoftheHerring—Burgess.Thisisalsoequippedwithanautomaticstabilitydeviceformaintainingthebalancetransversely.Thecurvatureoftheplanesisalsolaidoutonnewlines.Thatthisnewplaniseffectiveisevidencedbythefactthatthemachinehasbeenelevatedtoanaltitudeof40feetbyusingone—halfthepowerofthe30—horsepowermotor.
Thesystemofrudderandelevationcontrolisverysimple.Theaviatorsitsinfrontofthelowerplane，andextendinghisarms，graspstwosupportswhichextenddowndiagonallyinfront.Ontheundersideofthesesupportsjustbeneathhisfingersarethecontrolswhichoperatetheverticalrudder，intherear.Thus，ifhewishestoturntotheright，hepressesthecontrolunderthefingersofhisrighthand;iftotheleft，thatunderthefingersofhislefthand.Theelevatingrudderisoperatedbytheaviator’srightfoot，thecontrolbeingplacedonafoot—rest.
MotorIsExtremelyLight.
Nottheleastnotablefeatureofthecraftisitsmotor.
Althoughdeveloping，underload，30—horsepower，orthatofanordinaryautomobile，itweighs，complete，hardly100pounds.Havingoccasiontomoveitalittledistanceforinspection，Mr.Burgesspickeditupandwalkedoffwithit——cylinders，pistons，crankcaseandall，eventhemagneto，beingattached.Therearenotmany30—
horsepowerengineswhichcanbesohandled.Everythingaboutitisreducedtoitslowesttermsofsimplicity，andhence，ofweight.Asinglecamshaftoperatesnotonlyalloftheinletandexhaustvalves，butthemagnetoandgearwaterpump，aswell.Themotorisplaceddirectlybehindtheoperator，andthepropellerisdirectlymountedonthecrankshaft.
Thisweightoflessthan100pounds，itmustberemembered，isnotforthemotoralone;itincludestheentirepowerplantequipment.
The\"thrust\"ofthepropellerisalsoextraordinary，beingbetween250and260pounds.Theforceofthewinddisplacementisstrongenoughtoknockdownagood—sizedboyasoneyoungsterascertainedwhenhegotbehindthepropellerasitwasbeingtested.Hewasnotonlyknockeddownbutdrivenforsomedistanceawayfromthemachine.Thepropellerhasfourbladeswhicharebutlittlewiderthanalath.
MachineBuiltbyStudents.
StudentsattheUniversityofPennsylvania，headedbyLaurenceJ.Lesh，aprotegeofOctaveChanute，haveconstructedapracticalaeroplaneofordinarymaximumsize，inwhichisincorporatedmanynewideas.Themostuniqueoftheseistobefoundinthesteeringgear，andtheprovisionmadefortheaccommodationofapupilwhiletakinglessonsunderanexperiencedaviator.
Immediatelybackoftheaviatorisanextraseatandanextrasteeringwheelwhichworksintandemstylewiththefrontwheel.Bythisarrangementabeginnermaybeeasilyandquicklytaughttohaveperfectcontrolofthemachine.Thesetandemwheelsarealsohandyforpassengerswhomaywishtooperatethecarindependentlyofoneanother，itbeingunderstood，ofcourse，thattherewillbenoconflictofaction.
FrameSizeandEnginePower.
Theframehas36feetspreadandmeasures35feetfromthefrontedgetotheendofthetailintherear.ItisequippedwithtworearpropellersoperatedbyaRamsey8—cylindermotorof50horsepower，placedhorizontallyacrossthelowerplane，withthecrankshaftrunningclearthroughtheengine.
The\"PennsylvaniaI\"isthefirsttwo—propellerbiplanechainlesscar，thisschemehavingbeenadoptedinordertoavoidthecrossingofchains.ThelateralcontrolisbyanewinventionbyOctaveChanuteandLaurenceJ.
Lesh，forwhichLeshisnowapplyingforapatent.ThedevicewasworkedoutbeforetheWrightbrothers’suitwasbegun，andissaidtobesuperiortotheWrightwarpingortheCurtissailerons.Thelandingdeviceisalsonewindesign.Thisaeroplanewillweighabout1，500pounds，andwillcarryfuelforaflightof150miles，anditisexpectedtoattainaspeedofatleast45milesanhour.
Thereareothers，lotsofthem，toonumerousinfacttoadmitofmentioninabookofthissize.
CHAPTERXVIII.
DEMANDFORFLYINGMACHINES.
Asacommercialpropositionthemanufactureandsaleofmotor—equippedaeroplanesismakingmuchmorerapidadvancethanatfirstobtainedinthesimilarhandlingoftheautomobile.Great，andevenphenomenal，aswasthecommercialdevelopmentofthemotorcar，thatoftheflyingmachineisevengreater.Thisisastartlingstatement，butitisfullywarrantedbythefacts.
Itisbarelymorethanayearago（1909）thatattentionwasseriouslyattractedtothemotor—equippedaeroplaneasavehiclepossibleofmanipulationbyothersthanprofessionalaviators.Uptothattimesuchactualflightsasweremadewerealmostexclusivelywiththesolepurposeofdemonstratingthepracticabilityofthemachine，andthemeritsoftheideasastoshape，enginepower，etc.，ofthevariousproducers.
ResultsofBleriot’sDaring.
ItwasnotuntilBleriotflewacrossthestraitsofDoveronJuly25th，1909，thatthegeneralpublicawoketoafullrealizationofthefactthatitwaspossibleforothersthanprofessionalaviatorstoindulgeinaviation.
Bleriot’sfeatwasacceptedasproofthatatlastanabsolutelynewmeansofsport，pleasureandresearch，hadbeenpracticallydeveloped，andwaswithinthereachofallwhohadtheinclination，nerveandfinancialmeanstoadoptit.
Fromthiseventmaybedatedthebirthofthemodernflyingmachineintotheworldofbusiness.Theautomobilewastakenupbythegeneralpublicfromtheverystartbecauseitwasapropositioncomparativelyeasyofdemonstration.Therewasnothingmysteriousoruncannyinthefactthatawheeledvehiclecouldbepropelledonsolid，substantialroadsbymeansofenginepower.Andyetittook（comparativelyspeaking）alongtimetoreallypopularizethemotorcar.
WonderfulResultsinaYear.
Menoflargefinancialmeansengagedinthemanufactureofautomobiles，andexpendedfortunesinattractingpublicattentiontothemthroughthemediumofadvertisements，speedandroadcontests，etc.Bythesemeansamammothbusinesshasbeenbuiltup，butbringingthisbusinesstoitspresentproportionsrequiredyearsofpatientindustryandindomitablepluck.
Atthiswriting，lessthanayearfromthedaywhenBleriotcrossedthechannel，theactualsalesofflyingmachinesoutnumbertheactualsalesofautomobilesinthefirstyearoftheircommercialdevelopment.Thismayappearincredible，butitisafactasstatisticswillshow.
Inthisconnectionweshouldtakeintoconsiderationthefactthatuptoayearagotherewasnoseriousintentionofputtingflyingmachinesonthemarket;nopreparationshadbeenmadetoproducethemonacommercialscale;nomoneyhadbeenexpendedinadvertisementswithaviewtosellingthem.
SomeoftheActualResults.
Todayflyingmachinesarebeingproducedonacommercialbasis，andthereisabigdemandforthem.Thepeoplemakingthemareovercrowdedwithorders.Someoftheproducersarealreadymakingarrangementstoenlargetheirplantsandadvertisetheirproductforsalethesameasisbeingdonewithautomobiles，whileanumberofflyingmachinemotormakersarealreadypromotingthesaleoftheirwaresinthisway.
HereareafewactualfiguresofflyingmachinesalesmadebythemoreprominentproducerssinceJuly25th，1909.
SantosDumont，90machines;Bleriot，200;Farman，130;Clemenceau—Wright，80;Voisin，100;Antoinette，100.Manyoftheseordershavebeenfilledbydeliveryofthemachines，andinotherstheconstructionworkisunderway.
Theforegoingareallofforeignmake.InthiscountryCurtissandtheWrightsareengagedinsimilarwork，butnoactualfiguresoftheiroutputareobtainable.
LargerPlantsAreNecessary.
Andthissituationexistsdespitethefactthatnoneoftheproducersarereallyequippedwithadequateplantsforturningouttheirmachinesonamodern，business—
likebasis.Thedemandwassosuddenandunexpectedthatitfoundthempoorlypreparedtomeetit.This，however，isnowbeingremediedbytheerectionofspecialplants，theenlargementofothers，andtheintroductionofnewmachineryandotherlabor—savingconveniences.
Companies，withlargecapitalization，toengageintheexclusiveproductionofairshipsarebeingorganizedinmanypartsoftheworld.Onenotableinstanceofthisnatureisworthquotingasillustrativeofthemannerinwhichtheproductionofflyingmachinesisbeingcommercialized.ThisistheformationatFrankfort，Germany，oftheFlugmaschineWright，G.m.b.H.，withacapitalof$119，000，theKrupps，ofEssen，beinginterested.
PricesatWhichMachinesSell.
Thiswonderfuldemandfromthepublichascomenotwithstandingthefactthatthemachines，owingtolackoffacilitiesforwholesaleproduction，arefarfrombeingcheap.Suchdefinitequotationsasaremadeareonthefollowingbasis：
SantosDumont——Listprice$1，000，butowingtotherushofordersagentsarereadilygettingfrom$1，300to$1，500.Thisisthesmallestmachinemade.
Bleriot——Listprice$2，500.Thisisforthecross—
channeltype，withAnzanimotor.
Antoinette——Listpricefrom$4，000to$5，000，accordingtosize.
Wright——Listprice$5，600.
Curtiss——Listprice$5，000.
Thereis，however，nostabilityinpricesaspurchasersarealmostinvariablyreadytopayaconsiderablepremiumtofacilitatedelivery.
Themotoristhemostexpensivepartoftheflyingmachine.Motorpricesrangefrom$500to$2，000，thislatteramountbeingaskedfortheCurtissengine.
SystematicInstructionofAmateurs.
Inadditiontotheproductionofflyingmachinesmanyoftheexperiencedaviatorsaremakingabusinessoftheinstructionofamateurs.CurtissandtheWrightsinthiscountryhaveanumberofpupils，ashavealsotheprominentforeigners.Schoolsofinstructionarebeingopenedinvariouspartsoftheworld，notaloneasprivatemoney—makingventures，butinconnectionwithpubliceducationalinstitutions.OneoftheselatteristobefoundattheUniversityofBarcelona，Spain.
Theflyingmachineagent，themanwhohandlesthemachinesonacommission，hasalsobecomeaknownquantity，andwillsoonbeasnumerousashisbrotheroftheautomobile.Thesign\"JohnBird，agentforSkimmer’sFlyingMachine，\"isnolongeracuriosity.