\"FactsforMotorists，\"etc.etc.
AND
THOS.H.RUSSELL，A.M.，M.E.，CharterMemberoftheAeroClubofIllinois，Authorof\"HistoryoftheAutomobile，\"\"MotorBoats：ConstructionandOperation，\"etc.etc.
WITHINTRODUCTORYCHAPTERBY
OCTAVECHANUTE，C.E.，PresidentAeroClubofIllinois1912
PREFACE.
Thisbookiswrittenfortheguidanceofthenoviceinaviation——themanwhoseekspracticalinformationastothetheory，constructionandoperationofthemodernflyingmachine.Withthisobjectinviewthewordingisintentionallyplainandnon—technical.Itcontainssomepropositionswhich，sofarassatisfyingtheexpertsisconcerned，mightdoubtlessbebetterstatedintechnicalterms，butthiswoulddefeatthemainpurposeofitspreparation.
Consequently，whilefullyawareofitsshortcomingsinthisrespect，theauthorshavenoapologiestomake.
Inthestatingofatechnicalpropositionsoitmaybeclearlyunderstoodbypeoplenotversedintechnicalmattersitbecomesabsolutelynecessarytouselanguagemuchdifferentfromthatwhichanexpertwouldemploy，andthishasbeendoneinthisvolume.
Nomanofordinaryintelligencecanreadthisbookwithoutobtainingaclear，comprehensiveknowledgeofflyingmachineconstructionandoperation.Hewilllearn，notonlyhowtobuild，equip，andmanipulateanaeroplaneinactualflight，butwillalsogainathoroughunderstandingoftheprincipleuponwhichthesuspensionintheairofanobjectmuchheavierthantheairismadepossible.
Thislatterfeatureshouldmakethebookofinteresteventothosewhohavenointentionofconstructingoroperatingaflyingmachine.ItwillenablethemtobetterunderstandandappreciatetheperformancesofthedaringmenliketheWrightbrothers，Curtiss，Bleriot，Farman，Paulhan，Latham，andothers，whoseboldexperimentshavemadeaviationanactuality.
Forthosewhowishtoengageinthefascinatingpastimeofconstructionandoperationitisintendedasareliable，practicalguide.
Itmaybewelltoexplainthatthesub—headingsinthearticlesbyMr.Chanutewereinsertedbytheauthorswithouthisknowledge.Thepurposeofthiswasmerelytopreserveuniformityinthetypographyofthebook.
ThisexplanationismadeinjusticetoMr.Chanute.
THEAUTHORS.
INMEMORIAM.
OctaveChanute，\"thefatherofthemodernflyingmachine，\"
diedathishomeinChicagoonNovember23，1910，attheageof72years.Hislastworkintheinterestofaviationwastofurnishtheintroductorychaptertothefirsteditionofthisvolume，andtorendervaluableassistanceinthehandlingofthevarioussubjects.Heevenmadethetripfromhishometotheofficeofthepublishersoneinclementdaylastspring，tolookovertheproofsofthebookand，athissuggestion，severalimportantchangesweremade.Allthiswas\"alaboroflove\"onMr.Chanute’spart.Hegaveofhistimeandtalentsfreelybecausehewasenthusiasticinthecauseofaviation，andbecauseheknewtheauthorsofthisbookanddesiredtogivethemmaterialaidinthepreparationofthework——afavorthatwasmostsincerelyappreciated.
Theauthorsdesiretomakeacknowledgmentofmanycourtesiesinthewayofvaluableadvice，information，etc.，extendedbyMr.
OctaveChanute，C.E.，Mr.E.L.Jones，EditorofAeronautics，andthepublishersof，theNewEnglandAutomobileJournalandFly.
CONTENTS
ChapterI.EvolutionoftheTwo—SurfaceFlyingMachineIntroductoryChapterbyOctaveChanute，C.E.
II.TheoryDevelopmentandUseOriginoftheAeroplane——DevelopmentsbyChanuteandtheWrights——PracticalUsesandLimits.
III.MechanicalBirdActionWhattheMotorDoes——PuzzleinBirdSoaring.
IV.VariousFormsofFlyingMachinesHelicopters，OrnithoptersandAeroplanes——
Monoplanes，BiplanesandTriplanes.
V.ConstructingaGlidingMachinePlansandMaterialsRequired——EstimateofCost——
SizesandPreparationofVariousParts——PuttingthePartsTogetherVI.LearningtoFlyHowtoUsetheGlider——EffectofBodyMovements——RulesforBeginners——SafestPlacetoGlide.
VII.PuttingOntheRudderItsConstruction，ApplicationandUse.
VIII.TheRealFlyingMachineSurfaceAreaRequired——ProperSizeofFrameandAuxiliaries——InstallationofMotor——CostofConstructingMachine.
IX.SelectionoftheMotorEssentialFeatures——MultiplicityofCylinders——PowerRequired——KindandActionofPropellers——PlacingoftheMotorX.ProperDimensionsofMachinesFiguringOuttheDetails——HowtoEstimateLoadCapacity——DistributionoftheWeight——MeasurementsofLeadingMachines.
XI.PlaneandRudderControlVariousMethodsinUse——WheelsandHandandFootLeversXII.HowtoUsetheMachineRulesofLeadingAviators——RisingfromtheGround——ReasonableAltitude——PreservingEquilibrium——
LearningtoSteer.
XIII.PeculiaritiesofAeroplanePowerPressureoftheWind——HowtoDetermineUponPower——WhySpeedIsRequired——BirdfindFlyingMachineAreas.
XIV.AboutWindCurrents，Etc.
UncertaintyofDirectForce——TroubleWithGustyCurrents——WhyBirdActionIsImitated.
XV.TheElementofDangerRiskSmallUnderProperConditions——TwoFieldsofSafety——LessonsinRecentAccidents.
XVI.RadicalChangesBeingMadeResultsofRecentExperiments——NewDimensions——IncreasedSpeed——TheOneGoverningRule.
XVII.SomeoftheNewDesigns？AutomaticControlofPlaneStability——InventorHerring’sDevices——NovelIdeasofStudents.
XVIII.DemandforFlyingMachinesWonderfulResultsinaYear——FactoriesOver—
crowdedwithOrders.
XIX.LawoftheAirshipRightsofPropertyOwners——SomeLegalPeculiarities——DangerofTrespass.
XX.SoaringFlightXXI.FlyingMachinesvs.BalloonsXXII.ProblemsofAerialFlighXXIII.AmateursMayUseWrightPatentsXXIV.HintsonPropellerConstructionXXV.NewMotorsandDevicesXXVI.Monoplanes，Triplanes，MultiplanesXXVII.RecordsofVariousKindsFLYINGMACHINES：CONSTRUCTIONandOPERATION
CHAPTERI.
EVOLUTIONOFTWO—SURFACEFLYINGMACHINE.
ByOctaveChanute.
Iamaskedtosetforththedevelopmentofthe\"two—
surface\"typeofflyingmachinewhichisnowusedwithmodificationsbyWrightBrothers，Farman，[1]Delagrange，Herringandothers.
[1]Nowdead.
ThistypeoriginatedwithMr.F.H.Wenham，whopatenteditinEnglandin1866（No.1571），takingoutprovisionalpapersonly.IntheabridgmentofBritishpatentAeronauticalSpecifications（1893）itisdescribedasfollows：
\"Twoormoreaeroplanesarearrangedoneabovetheother，andsupportaframeworkorcarcontainingthemotivepower.Theaeroplanesaremadeofsilkorcanvasstretchedonaframebywoodenrodsorsteelribs.
Whenmanualpowerisemployedthebodyisplacedhorizontally，andoarsorpropellersareactuatedbythearmsorlegs.
\"Astartmaybeobtainedbyloweringthelegsandrunningdownhillorthemachinemaybestartedfromamovingcarriage.Oneormorescrewpropellersmaybeappliedforpropellingwhensteampowerisemployed.
OnJune27，1866，Mr.Wenhamreadbeforethe\"AeronauticalSocietyofGreatBritain，\"thenrecentlyorganized，theablestpapereverpresentedtothatsociety，andtherebybreathedintoitaspiritwhichhascontinuedtothisday.Inthispaperhedescribedhisobservationsofbirds，discussedthelawsgoverningflightastothesurfacesandpowerrequiredbothwithwingsandscrews，andhethengaveanaccountofhisownexperimentswithmodelsandwithaeroplanesofsufficientsizetocarrytheweightofaman.
SecondWenhamAeroplane.
Hissecondaeroplanewassixteenfeetfromtiptotip.
Atrussedsparatthebottomcarriedsixsuperposedbandsofthinhollandfabricfifteenincheswide，connectedwithverticalwebsofhollandtwofeetapart，thusvirtuallygivingalengthofwingofninety—sixfeetandonehundredandtwentysquarefeetofsupportingsurface.
Themanwasplacedhorizontallyonabaseboardbeneaththespar.Thisapparatuswhentriedinthewindwasfoundtobeunmanageablebyreasonoftheflutteringmotionsofthefabric，whichwasinsufficientlystiffenedwithcrinolinesteel，butMr.Wenhampointedoutthatthisinnowayinvalidatedtheprincipleoftheapparatus，whichwastoobtainlargesupportingsurfaceswithoutincreasingundulytheleverageandconsequentweightofsparrequired，bysimplysuperposingthesurfaces.
Thisprincipleisentirelysoundanditissurprisingthatitis，tothisday，notrealizedbythoseaviatorswhoarehankeringformonoplanes.
ExperimentsbyStringfellow.
ThenextmantotestanapparatuswithsuperposedsurfaceswasMr.Stringfellow，who，becomingmuchimpressedwithMr.Wenham’sproposal，producedalargishmodelattheexhibitionoftheAeronauticalSocietyin1868.Itconsistedofthreesuperposedsurfacesaggregating28
squarefeetandatailof8squarefeetmore.
Theweightwasunder12poundsanditwasdrivenbyacentralpropelleractuatedbyasteamengineoverestimatedatone—thirdofahorsepower.Itransuspendedtoawireonitstrialsbutfailedoffreeflight，inconsequenceofdefectiveequilibrium.ThisapparatushassincebeenrebuiltandisnowintheNationalMuseumoftheSmithsonianInstitutionatWashington.
Linfield’sUnsuccessfulEfforts.
In1878Mr.LinfieldtestedanapparatusinEnglandconsistingofacigar—shapedcar，towhichwasattachedoneachsideframesfivefeetsquare，containingeachtwenty—fivesuperposedplanesofstretchedandvarnishedlineneighteenincheswide，andonlytwoinchesapart，thusremindingoneofaSpanishdonkeywithpanniers.
Thewholeweighedtwohundredandfortypounds.Thiswastestedbybeingmountedonaflatcarbehindalocomotivegoing40milesanhour.Whentowedbyalinefifteenfeetlongtheapparatusroseonlyalittlefromthecarandexhibitedsuchunstableequilibriumthattheexperimentwasnotrenewed.Theliftwasonlyaboutone—
thirdofwhatitwouldhavebeenhadtheplanesbeenproperlyspaced，saytheirfullwidthapart，insteadofone—ninthaserroneouslydevised.
Renard’s\"DirigibleParachute.\"
In1889CommandantRenard，theeminentsuperintendentoftheFrenchAeronauticalDepartment，exhibitedattheParisExpositionofthatyear，anapparatusexperimentedwithsomeyearsbefore，whichhetermeda\"dirigibleparachute.\"Itconsistedofanoviformbodytowhichwerepivotedtwouprightslatscarryingabovethebodyninelongsuperposedflatbladesspacedaboutone—thirdoftheirwidthapart.Whenthisapparatuswasproperlysetatanangletothelongitudinalaxisofthebodyanddroppedfromaballoon，ittravelledbackagainstthewindforaconsiderabledistancebeforealighting.Thecoursecouldbevariedbyarudder.NopracticalapplicationseemstohavebeenmadeofthisdevicebytheFrenchWarDepartment，butMr.J.P.
Holland，theinventorofthesubmarineboatwhichbearshisname，proposedin1893anarrangementofpivotedframeworkattachedtothebodyofaflyingmachinewhichcombinestheprincipleofCommandantRenardwiththecurvedbladesexperimentedwithbyMr.Phillips，nowtobenoticed，withtheadditionofliftingscrewsinsertedamongtheblades.
PhillipsFailsonStabilityProblem.
In1893Mr.HoratioPhillips，ofEngland，aftersomeveryinterestingexperimentswithvariouswingsections，fromwhichhededucedconclusionsastotheshapeofmaximumlift，testedanapparatusresemblingaVenetianblindwhichconsistedoffiftywoodenslatsofpeculiarshape，22feetlong，oneandahalfincheswide，andtwoinchesapart，setintenverticaluprightboards.
Allthiswascarrieduponabodyprovidedwiththreewheels.Itweighed420poundsandwasdrivenat40
milesanhouronawoodensidewalkbyasteamengineofninehorsepowerwhichactuatedatwo—bladedscrew.
Theliftwassatisfactory，beingperhaps70poundsperhorsepower，buttheequilibriumwasquitebadandtheexperimentswerediscontinued.Theyweretakenupagainin1904withasimilarapparatuslargeenoughtocarryapassenger，butthelongitudinalequilibriumwasfoundtobedefective.Thenin1907anewmachinewastested，inwhichfoursetsofframes，carryingsimilarsetsofslat\"sustainers\"wereinserted，andwiththisarrangementthelongitudinalstabilitywasfoundtobeverysatisfactory.Thewholeapparatus，withtheoperator，weighed650pounds.Itflewabout200yardswhendrivenbyamotorof20to22h.p.at30milesanhour，thusexhibitingaliftofabout32poundsperh.p.，whileitwillberememberedthattheaeroplaneofWrightBrothersexhibitsaliftingcapacityof50poundstotheh.p.
Hargrave’sKiteExperiments.
Afterexperimentingwithverymanymodelsandbuildingnolessthaneighteenmonoplaneflyingmodelmachines，actuatedbyrubber，bycompressedairandbysteam，Mr.LawrenceHargrave，ofSydney，NewSouthWales，inventedthecellularkitewhichbearshisnameandmadeitknowninapapercontributedtotheChicagoConferenceonAerialNavigationin1893，describingseveralvarieties.Themodernconstructioniswellknown，andconsistsoftwocells，eachofsuperposedsurfaceswithverticalsidefins，placedonebehindtheotherandconnectedbyarodorframe.Thisflieswithgreatsteadinesswithoutatail.Mr.Hargrave’sideawastouseateamofthesekites，belowwhichheproposedtosuspendamotorandpropellerfromwhichalinewouldbecarriedtoananchorintheground.Thenbyactuatingthepropellerthewholeapparatuswouldmoveforward，pickuptheanchorandflyaway.Hesaid：
\"Thenextstepisclearenough，namely，thataflyingmachinewithacresofsurfacecanbesafelygotunderwayoranchoredandhauledtothegroundbymeansofthestringofkites.\"
Thefirsttentativeexperimentsdidnotresultwellandemphasizedthenecessityforalightmotor，sothatMr.
Hargravehassincebeenengagedindevelopingone，nothavingconvenientaccesstothosewhichhavebeenproducedbytheautomobiledesignersandbuilders.
ExperimentsWithGliderModel.
Andhereacuriousreminiscencemaybeindulgedin.
In1888thepresentwriterexperimentedwithatwo—cellglidingmodel，preciselysimilartoaHargravekite，aswillbeconfirmedbyMr.Herring.Itwasfrequentlytestedbylaunchingfromthetopofathree—storyhouseandglideddownwardverysteadilyinallsortsofbreezes，buttheangleofdescentwasmuchsteeperthanthatofbirds，andtheweightsustainedpersquarefootwaslessthanwithsinglecells，inconsequenceofthelessersupportaffordedbytherearcell，whichoperateduponairalreadysetinmotiondownwardbythefrontcell，sonothingmorewasdonewithit，foritneveroccurredtothewritertotryitasakiteandhethusmissedthedistinctionwhichattachestoHargrave’sname.
SirHiramMaximalsointroducedforeandaftsuperposedsurfacesinhiswondrousflyingmachineof1893，buthereliedchieflyfortheliftuponhismainlargesurfaceandthisnecessitatedsomanyguys，topreventdistortion，asgreatlytoincreasetheheadresistanceandthis，togetherwiththeunstableequilibrium，madeitevidentthatthedesignofthemachinewouldhavetobechanged.
HowLilienthalWasKilled.
In1895，OttoLilienthal，thefatherofmodernaviation，themantowhosemethodofexperimentingalmostallpresentsuccessesaredue，aftermakingsomethingliketwothousandglideswithmonoplanes，addedasuperposedsurfacetohisapparatusandfoundthecontrolofitmuchimproved.Thetwosurfaceswerekeptapartbytwostrutsorverticalpostswithafewguywires，buttheconnectingjointswereweakandtherewasnothingliketrussing.Thiseventuallycosthismostusefullife.
Twoweeksbeforethatdistressinglosstoscience，HerrWilhelmKress，thedistinguishedandveteranaviatorofVienna，witnessedanumberofglidesbyLilienthalwithhisdouble—deckedapparatus.Henoticedthatitwasmuchwrackedandwobblyandwrotetomeaftertheaccident：\"Theconnectionofthewingsandthesteeringarrangementwereverybadandunreliable.I
warnedHerrLilienthalveryseriously.Hepromisedmethathewouldsoonputitinorder，butIfearthathedidnotattendtoitimmediately.\"
Inpointoffact，Lilienthalhadbuiltanewmachine，uponadifferentprinciple，fromwhichheexpectedgreatresults，andintendedtomakebutveryfewmoreflightswiththeoldapparatus.Heunwiselymadeonetoomanyand，likePilcher，wasthevictimofadistortedapparatus.Probablyoneofthejointsofthestrutsgaveway，theuppersurfaceblewbackandLilienthal，whowaswellforwardonthelowersurface，waspitchedheadlongtodestruction.
ExperimentsbytheWriter.
In1896，assistedbyMr.HerringandMr.Avery，I
experimentedwithseveralfullsizedglidingmachines，carryingaman.ThefirstwasaLilienthalmonoplanewhichwasdeemedsocrankythatitwasdiscardedaftermakingaboutonehundredglides，sixweeksbeforeLilienthal’saccident.Thesecondwasknownasthemultiplewingedmachineandfinallydevelopedintofivepairsofpivotedwings，trussedtogetheratthefrontandonepairintherear.Itglidedatanglesofdescentof10or11degreesorofoneinfive，andthiswasdeemedtoosteep.ThenMr.Herringandmyselfmadecomputationstoanalyzetheresistances.Weattributedmuchofthemtothefivefrontsparsofthewingsandonasheetofcross—barredpaperIatoncedrewthedesignforanewthree—deckedmachinetobebuiltbyMr.Herring.
Beingabuilderofbridges，Itrussedthesesurfacestogether，inordertoobtainstrengthandstiffness.Whentestedinglidingflightthelowersurfacewasfoundtooneartheground.Itwastakenoffandtheremainingapparatusnowconsistedoftwosurfacesconnectedtogetherbyagirdercomposedofverticalpostsanddiagonalties，specificallyknownasa\"Pratttruss.\"ThenMr.HerringandMr.Averytogetherdevisedandputonanelasticattachmenttothetail.Thismachineprovedasuccess，itbeingsafeandmanageable.Over700glidesweremadewithitatanglesofdescentof8
to10degrees，oroneinsixtooneinseven.
FirstProposedbyWenham.
Theelastictailattachmentandthetrussingoftheconnectingframeofthesuperposedwingsweretheonlynoveltiesinthismachine，forthesuperposingofthesurfaceshadfirstbeenproposedbyWenham，butinaccordancewiththepopularperception，whichbestowsallthecredituponthemanwhoaddsthelasttouchmakingforsuccesstothelaborsofhispredecessors，themachinehassincebeenknownbymanypersonsasthe\"Chanutetype\"ofgliders，muchtomypersonalgratification.
Ithassincebeenimprovedinmanyways.WrightBrothers，disregardingthefashionwhichprevailsamongbirds，haveplacedthetailinfrontoftheirapparatusandcalleditafrontrudder，besidesplacingtheoperatorinhorizontalpositioninsteadofupright，asIdid;andalsoprovidingamethodofwarpingthewingstopreserveequilibrium.FarmanandDelagrange，undertheveryableguidanceandconstructiveworkofVoisinbrothers，thensubstitutedmanydetails，includingaboxtailforthedart—liketailwhichIused.Thismayhaveincreasedtheresistance，butitaddstothesteadiness.NowthetendencyinFranceseemstobetogobacktothemonoplane.
MonoplaneIdeaWrong.
Theadvocatesofthesinglesupportingsurfaceareprobablymistaken.Itistruethatasinglesurfaceshowsagreaterliftpersquarefootthansuperposedsurfacesforagivenspeed，buttheincreasedweightduetoleveragemorethancounterbalancesthisadvantagebyrequiringheavysparsandsomeguys.Ibelievethatthefutureaeroplanedynamicflierwillconsistofsuperposedsurfaces，and，nowthatithasbeenfoundthatbyimbeddingsuitablyshapedsparsinthecloththeheadresistancemaybemuchdiminished，Iseefewobjectionstosuperposingthree，fourorevenfivesurfacesproperlytrussed，andthusobtainingacompact，handy，manageableandcomparativelylightapparatus.[2]
[2]Aeronautics.
CHAPTERII.
THEORY，DEVELOPMENT，ANDUSE.
Whileeverycraftthatnavigatestheairisanairship，allairshipsarenotflyingmachines.Theballoon，forinstance，isanairship，butitisnotwhatisknownamongaviatorsasaflyingmachine.Thislattertermisproperlyusedonlyinreferringtoheavier—than—airmachineswhichhavenogas—bagliftingdevices，andaremadetoreallyflybytheapplicationofenginepropulsion.
MechanicalBirds.
Allsuccessfulflyingmachines——andthereareanumberofthem——arebasedonbirdaction.Thevariousdesignershavestudiedbirdflightandsoaring，mastereditstechniqueasdevisedbyNature，andthemodernflyingmachineistheresult.Onanexaggerated，enlargedscalethemachineswhicharenownavigatingtheairarenothingmorenorlessthanmechanicalbirds.
OriginoftheAeroplane.
OctaveChanute，ofChicago，maywellbecalled\"thedeveloperoftheflyingmachine.\"Leavingballoonsandvariousformsofgas—bagsoutofconsideration，otherexperimenters，notablyLangleyandLilienthal，antedatedhiminattemptingthenavigationoftheaironaeroplanes，orflyingmachines，butnoneofthemwerewhollysuccessful，anditremainedforChanutetodemonstratethepracticabilityofwhatwasthencalledtheglidingmachine.Thistermwasadoptedbecausetheapparatuswas，asthenameimplies，simplyaglidingmachine，beingwithoutmotorpropulsion，andintendedsolelytosolvetheproblemofthebestformofconstruction.Thebiplane，usedbyChanutein1896，isstillthebasisofmostsuccessfulflyingmachines，theonlyradicaldifferencebeingthatmotors，rudders，etc.，havebeenadded.
CharacterofChanute’sExperiments.
ItwastheprivilegeoftheauthorofthisbooktobeMr.Chanute’sguestatMillers，Indiana，in1896，when，incollaborationwithMessrs.HerringandAvery，hewasconductingtheseriesofexperimentswhichhavesincemadepossibletheconstructionofthemodernflyingmachinewhichsuchsuccessfulaviatorsastheWrightbrothersandothersarenowusing.Itwasawildcountry，muchfrequentedbyeagles，hawks，andsimilarbirds.Theenthusiastictrio，Chanute，HerringandAvery，wouldwatchforhourstheevolutionsofsomebigbirdintheair，agreeingintheendontheverdict，\"Whenwemastertheprincipleofthatbird’ssoaringwithoutwingaction，wewillhavecomeclosetosolvingtheproblemoftheflyingmachine.\"
AeroplanesofvariousformswereconstructedbyMr.
ChanutewiththeassistanceofMessrs.HerringandAveryuntil，atthetimeofthewriter’svisit，theyhadsettleduponthebiplane，ortwo—surfacemachine.Mr.
Herringlaterequippedthiswitharudder，andmadeotheradditions，butthegeneralideaisstillthebasisoftheWright，Curtiss，andothermachinesinwhich，bytheaidofgasolenemotors，longflightshavebeenmade.
DevelopmentsbytheWrights.
In1900theWrightbrothers，WilliamandOrville，whoweretheninthebicyclebusinessinDayton，Ohio，becameinterestedinChanute’sexperimentsandcommunicatedwithhim.TheresultwasthattheWrightstookupChanute’sideasanddevelopedthemfurther，makingmanyadditionsoftheirown，oneofwhichwastheplacingofarudderinfront，andthelocationoftheoperatorhorizontallyonthemachine，thusdiminishingbyfour—fifthsthewindresistanceoftheman’sbody.
ForthreeyearstheWrightsexperimentedwiththegliderbeforeventuringtoaddamotor，whichwasnotdoneuntiltheyhadthoroughlymasteredthecontroloftheirmovementsintheair.
LimitsoftheFlyingMachine.
Intheopinionofcompetentexpertsitisidletolookforacommercialfuturefortheflyingmachine.Thereis，andalwayswillbe，alimittoitscarryingcapacitywhichwillprohibititsemploymentforpassengerorfreightpurposesinawholesaleorgeneralway.Therearesome，ofcourse，whowillarguethatbecauseamachinewillcarrytwopeopleanothermaybeconstructedthatwillcarryadozen，butthosewhomakethiscontentiondonotunderstandthetheoryofweightsustentationintheair;orthatthegreatertheloadthegreatermustbetheliftingpower（motorsandplanesurface），andthatthereisalimittothese——aswillbeexplainedlateron——beyondwhichtheaviatorcannotgo.
SomePracticalUses.
Atthesametimetherearefieldsinwhichtheflyingmachinemaybeusedtogreatadvantage.Theseare：
Sports——Flyingmachineracesorflightswillalwaysbepopularbyreasonoftheelementofdanger.Itisastrange，butneverthelessatrueproposition，thatitisthiselementwhichaddszesttoallsportingevents.
Scientific——Forexplorationofotherwiseinaccessibleregionssuchasdeserts，mountaintops，etc.
Reconnoitering——Intimeofwarflyingmachinesmaybeusedtoadvantagetospyoutanenemy’sencampment，ascertainitsdefenses，etc.
CHAPTERIII.
MECHANICALBIRDACTION
Inordertounderstandthetheoryofthemodernflyingmachineonemustalsounderstandbirdactionandwindaction.Inthisconnectionthefollowingsimpleexperimentwillbeofinterest：
Takeacircular—shapedbitofcardboard，likethelidofahatbox，andremovethebent—overportionsoastohaveaperfectlyflatsurfacewithaclean，sharpedge.
Holdingthecardboardatarm’slength，withdrawyourhand，leavingthecardboardwithoutsupport.Whatistheresult？Thecardboard，beingheavierthanair，andhavingnothingtosustainit，willfalltotheground.
Pickitupandthrowit，withconsiderableforce，againstthewindedgewise.Whathappens？Insteadoffallingtotheground，thecardboardsailsalongonthewind，remainingafloatsolongasitisinmotion.Itseekstheground，bygravity，onlyasthemotionceases，andthenbyeasystages，insteadofdroppingabruptlyasinthefirstinstance.
Herewehaveahomely，butaccurateillustrationoftheactionoftheflyingmachine.Themotordoesforthelatterwhattheforceofyourarmdoesforthecardboard——
impartsamotionwhichkeepsitafloat.Theonlyrealdifferenceisthatthemotiongivenbythemotoriscontinuousandmuchmorepowerfulthanthatgivenbyyourarm.Theactionofthelatterislimitedandtheendofitspropulsiveforceisreachedwithinasecondortwoafteritisexerted，whiletheactionofthemotorisprolonged.
AnotherSimpleIllustration.
Anothersimplemeansofillustratingtheprincipleofflyingmachineoperation，sofarassustentationandtheelevationanddepressionoftheplanesisconcerned，isexplainedintheaccompanyingdiagram.
Aisapieceofcardboardabout2by3inchesinsize.
BisapieceofpaperofthesamesizepastedtooneedgeofA.Ifyoubendthepapertoacurve，withconvexsideupandblowacrossitasshowninFigureC，thepaperwillriseinsteadofbeingdepressed.Thedottedlinesshowthattheairispassingoverthetopofthecurvedpaperandyet，nomatterhowhardyoumayblow，theeffectwillbetoelevatethepaper，despitethefactthattheairispassingover，insteadofunderthecurvedsurface.
InFigureDwehaveanoppositeeffect.HerethepaperisinacurveexactlythereverseofthatshowninFigureC，bringingtheconcavesideup.Nowifyouwillagainblowacrossthesurfaceofthecardtheactionofthepaperwillbedownward——itwillbeimpossibletomakeitrise.Theharderyoublowthegreaterwillbethedownwardmovement.
PrincipleInGeneralUse.
Thisprincipleistakenadvantageofintheconstructionofallsuccessfulflyingmachines.Makersofmonoplanesandbiplanesalikeadheretocurvedbodies，withtheconcavesurfacefacingdownward.Straightplanesweretriedforatime，butfoundgreatlylackinginthepowerofsustentation.Bycurvingtheplanes，andplacingtheconcavesurfacedownward，asortofinvertedbowlisformedinwhichtheairgathersandexertsabuoyanteffect.Justwhattheratioofthecurveshouldbeisamatterofcontention.Insomeinstancesoneinchtothefootisfoundtobesatisfactory;inothersthisisdoubled，andthereareafewcasesinwhichacurveofasmuchas3inchestothefoothasbeenused.
Righthereitmightbewelltoexplainthattheword\"plane\"appliedtoflyingmachinesofmodernconstructionisinrealityamisnomer.Planeindicatesaflat，levelsurface.Asmostsuccessfulflyingmachineshavecurvedsupportingsurfacesitisclearlywrongtospeakof\"planes，\"or\"aeroplanes.\"Usage，however，hasmadethetermsconvenientand，astheyaregenerallyacceptedandunderstoodbythepublic，theyareusedinlikemannerinthisvolume.
GettingUnderHeadway.
Abird，onfirstrisingfromtheground，orbeginningitsflightfromatree，willflapitswingstogetunderheadway.Hereagainwehaveanotherillustrationofthemannerinwhichaflyingmachinegetsunderheadway——
themotorimpartstheforcenecessarytoputthemachineintotheair，butrightherethesimilarityceases.
Ifthemachineistobekeptafloatthemotormustbekeptmoving.Aflyingmachinewillnotsustainitself;
itwillnotremainsuspendedintheairunlessitisunderheadway.Thisisbecauseitisheavierthanair，andgravitydrawsittotheground.
PuzzleinBirdSoaring.
Butabird，whichisalsoheavierthanair，willremainsuspended，inacalm，willevensoarandmoveinacircle，withoutapparentmovementofitswings.Thisisexplainedonthetheorythattherearegenerallyverticalcolumnsofairincirculationstrongenoughtosustainabird，butmuchtooweaktoexertanyliftingpoweronaflyingmachine，Itiseasytounderstandhowabirdcanremainsuspendedwhenthewindisinaction，butitssuspensioninaseemingdeadcalmwasapuzzletoscientistsuntilMr.Chanuteadvancedthepropositionofverticalcolumnsofair.
ModeledCloselyAfterBirds.
Sofaraspossible，buildersofflyingmachineshavetakenwhatmaybecalled\"thearchitecture\"ofbirdsasamodel.Thisisreadilynoticeableintheformofconstruction.Whenabirdisinmotionitswings（exceptwhenflapping）areextendedinastraightlineatrightanglestoitsbody.Thisbringsasharp，thinedgeagainsttheair，offeringtheleastpossiblesurfaceforresistance，whileatthesametimeabroadsurfaceforsupportisaffordedbytheflat，undersideofthewings.
Identicallythesamethingisdoneintheconstructionoftheflyingmachine.
Note，forinstance，themarkedsimilarityinformasshownintheillustrationinChapterII.HereAisthebird，andBthegeneraloutlineofthemachine.Thethinedgeoftheplaneinthelatterisalmostaduplicateofthatformedbytheoutstretchedwingsofthebird，whiletherudderplaneintherearservesthesamepurposeasthebird’stail.
CHAPTERIV.
VARIOUSFORMSOFFLYINGMACHINES.
Therearethreedistinctandradicallydifferentformsofflyingmachines.Theseare：
Aeroplanes，helicoptersandornithopers.
Ofthesetheaeroplanetakesprecedenceandisusedalmostexclusivelybysuccessfulaviators，thehelicoptersandornithopershavingbeentriedandfoundlackinginsomevitalfeatures，whileatthesametimeinsomerespectsthehelicopterhasadvantagesnotfoundintheaeroplane.
WhattheHelicopterIs.
Thehelicoptergetsitsnamefrombeingfittedwithverticalpropellersorhelices（seeillustration）bytheactionofwhichthemachineisraiseddirectlyfromthegroundintotheair.Thisdoesawaywiththenecessityforgettingthemachineunderaglidingheadwaybeforeitfloats，asisthecasewiththeaeroplane，andconsequentlythehelicoptercanbehandledinamuchsmallerspacethanisrequiredforanaeroplane.This，inmanyinstances，isanimportantadvantage，butitistheonlyonethehelicopterpossesses，andismorethanovercomebyitsdrawbacks.Themostseriousoftheseisthatthehelicopterisdeficientinsustainingcapacity，andrequirestoomuchmotivepower.
FormoftheOrnithopter.
Theornithopterhashingedplaneswhichworklikethewingsofabird.Atfirstthoughtthiswouldseemtobethecorrectprinciple，andmostoftheearlyexperimentersconductedtheiroperationsonthisline.Itisnowgenerallyunderstood，however，thatthebirdinsoaringisinrealityanaeroplane，itsextendedwingsservingtosustain，aswellaspropel，thebody.Atanyratetheornithoperhasnotbeensuccessfulinaviation，andhasbeeninterestingmainlyasaningenioustoy.
Attemptstoconstructitonascalethatwouldpermitofitsusebymaninactualaerialflightshavebeenfarfromencouraging.
ThreeKindsofAeroplanes.
Therearethreeformsofaeroplanes，withallofwhichmoreorlesssuccesshasbeenattained.Theseare：
Themonoplane，aone—surfacedplane，likethatusedbyBleriot.
Thebiplane，atwo—surfacedplane，nowusedbytheWrights，Curtiss，Farman，andothers.
Thetriplane，athree—surfacedplaneThisformisbutlittleused，itsonlyprominentadvocateatpresentbeingElleLavimer，aDanishexperimenter，whohasnotthusfaraccomplishedmuch.
Whateverofrealsuccesshasbeenaccomplishedinaviationmaybecreditedtothemonoplaneandbiplane，withthebalanceinfavorofthelatter.Themonoplaneisthemoresimpleinconstructionand，whereweight—
sustainingcapacityisnotaprimerequisite，mayprobablybefoundthemostconvenient.Thisopinionisbasedonthefactthatthesmallerthesurfaceoftheplanethelesswillbetheresistanceofferedtotheair，andthegreaterwillbethespeedatwhichthemachinemaybemoved.Ontheotherhand，thebiplanehasamuchgreaterplanesurface（doublethatofamonoplaneofthesamesize）andconsequentlymuchgreaterweight—
carryingcapacity.
DifferencesinBiplanes.
Whileallbiplanesareofthesamegeneralconstructionsofarasthemainplanesareconcerned，eachaviatorhashisownideasastothe\"rigging.\"
Wright，forinstance，placesadoublehorizontalrudderinfront，withaverticalrudderintherear.Therearenopartitionsbetweenthemainplanes，andthebicyclewheelsusedonotherformsarereplacedbyskids.
Voisin，onthecontrary，dividesthemainplaneswithverticalpartitionstoincreasestabilityinturning;usesasingle—planehorizontalrudderinfront，andabigbox—
tailwithverticalrudderattherear;alsothebicyclewheels.
Curtissattacheshorizontalstabilizingsurfacestotheupperplane;hasadoublehorizontalrudderinfront，withaverticalrudderandhorizontalstabilizingsurfacesinrear.Alsothebicyclewheelalightinggear.
CHAPTERV.
CONSTRUCTINGAGLIDINGMACHINE.
Firstdecideuponthekindofamachineyouwant——
monoplane，biplane，ortriplane.Foranovicethebiplanewill，asarule，befoundthemostsatisfactoryasitismorecompactandthereforethemoreeasilyhandled.
Thiswillbeeasilyunderstoodwhenwerealizethatthesurfaceofaflyingmachineshouldbelaidoutinproportiontotheamountofweightitwillhavetosustain.
Thegenerallyacceptedruleisthat152squarefeetofsurfacewillsustaintheweightofanaverage—sizedman，say170pounds.Nowitfollowsthatifthese152squarefeetofsurfaceareusedinoneplane，asinthemonoplane，thelengthandwidthofthisplanemustbegreaterthanifthesameamountofsurfaceissecuredbyusingtwoplanes——thebiplane.Thisresultsinthebiplanebeingmorecompactandthereforemorereadilymanipulatedthanthemonoplane，whichisanimportantitemforanovice.
GlidertheBasisofSuccess.
Flyingmachineswithoutmotorsarecalledgliders.Inmakingaflyingmachineyoufirstconstructtheglider.
Ifyouuseitinthisformitremainsaglider.Ifyouinstallamotoritbecomesaflyingmachine.Youmusthaveagoodgliderasthebasisofasuccessfulflyingmachine.
Itwillbewellforthenovice，themanwhohasneverhadanyexperienceasanaviator，tobeginwithagliderandmasteritsconstructionandoperationbeforeheessaysthemorepretentioustaskofhandlingafully—
equippedflyingmachine.Infact，itisessentialthatheshoulddoso.
PlansforHandyGlider.
Agliderwithaspread（advancingedge）of20feet，andabreadthordepthof4feet，willbeaboutrighttobeginwith.Twoplanesofthissizewillgivethe152squareyardsofsurfacenecessarytosustainaman’sweight.
Rememberthatinreferringtoflyingmachinemeasurements\"spread\"takestheplaceofwhatwouldordinarilybecalled\"length，\"andinvariablyappliestothelongoradvancingedgeofthemachinewhichcutsintotheair.
Thus，agliderisspokenofasbeing20feetspread，and4feetindepth.Sofarasmasteringthecontrolofthemachineisconcerned，learningtobalanceone’sselfintheair，guidingthemachineinanydesireddirectionbychangingthepositionofthebody，etc.，allthismaybelearnedjustasreadily，andperhapsmoreso，witha20—
footgliderthanwithalargerapparatus.
KindofMaterialRequired.
Therearethreeall—importantfeaturesinflyingmachineconstruction，viz.：lightness，strengthandextremerigidity.Spruceisthewoodgenerallyusedforgliderframes.Oak，ashandhickoryareallstronger，buttheyarealsoconsiderablyheavier，andwherethesavingofweightisessential，thedifferenceislargelyinfavorofspruce.Thiswillbeseeninthefollowingtable：
WeightTensileCompressivepercubicft.StrengthStrengthWoodinlbs.lbs.persq.in.lbs.persqin.
Hickory5312，0008，500
Oak5012，0009，000
Ash3812，0006，000
Walnut388，0006，000
Spruce258，0005，000
Pine255，0004，500
Consideringthemarkedsavinginweightsprucehasagreaterpercentageoftensilestrengththananyoftheotherwoods.Itisalsoeasiertofindinlong，straight—
grainedpiecesfreefromknots，anditisthiskindonlythatshouldbeusedinflyingmachineconstruction.
YouwillnextneedsomespoolsorhanksofNo.6
linenshoethread，metalsockets，asupplyofstrongpianowire，aquantityofclosely—wovensilkorcottoncloth，glue，turnbuckles，varnish，etc.
NamesoftheVariousParts.
Thelongstrips，fourinnumber，whichformthefrontandrearedgesoftheupperandlowerframes，arecalledthehorizontalbeams.Theseareeach20feetinlength.
Thesehorizontalbeamsareconnectedbyuprightstrips，4feetlong，calledstanchions.Thereareusually12ofthese，sixonthefrontedge，andsixontherear.Theyservetoholdtheupperplaneawayfromthelowerone.
Nextcomestheribs.Theseare4feetinlength（projectingforafootovertherearbeam），andwhileintendedprincipallyasasupporttotheclothcoveringoftheplanes，alsotendtoholdtheframetogetherinahorizontalpositionjustasthestanchionsdointhevertical.
Thereareforty—oneoftheseribs，twenty—oneontheupperandtwentyonthelowerplane.Thencomethestruts，themainpieceswhichjointhehorizontalbeams.Allofthesepartsareshownintheillustrations，referencetowhichwillmakethemeaningofthevariousnamesclear.
QuantityandCostofMaterial.
Forthehorizontalbeamsfourpiecesofspruce，20feetlong，11/2incheswideand3/4inchthickarenecessary.
Thesepiecesmustbestraight—grain，andabsolutelyfreefromknots.Ifitisimpossibletoobtainclearpiecesofthislength，shorteronesmaybespliced，butthisisnotadvisedasitaddsmateriallytotheweight.Thetwelvestanchionsshouldbe4feetlongand7/8inchindiameterandroundedinformsoastoofferaslittleresistanceaspossibletothewind.Thestruts，therearetwelveofthem，are3feetlongby11/4x1/2inch.Fora20—footbiplaneabout20yardsofstoutsilkorunbleachedmuslin，ofstandardoneyardwidth，willbeneeded.Theforty—oneribsareeach4feetlong，and1/2inchsquare.ArollofNo.12pianowire，twenty—foursockets，apackageofsmallcoppertacks，apotofglue，andsimilaraccessorieswillberequired.Theentirecostofthismaterialshouldnotexceed$20.Thewoodandclothwillbethetwolargestitems，andtheseshouldnotcostmorethan$10.Thisleaves$10forthevarnish，wire，tacks，glue，andotherincidentals.Thisestimateismadeforcostofmaterialsonly，itbeingtakenforgrantedthattheexperimenterwillconstructhisownglider.Shouldtheservicesofacarpenterberequiredthetotalcostwillprobablyapproximate$60or$70.
ApplicationoftheRudders.
Thefiguresgivenalsoincludetheexpenseofrudders，butthedetailsofthesehavenotbeenincludedasthegliderisreallycompletewithoutthem.SomeofthebestflightsthewritereversawweremadebyMr.A.M.Herringinagliderwithoutarudder，andyettherecanbenodoubtthatarudder，properlyproportionedandplaced，especiallyarearrudder，isofgreatvaluetotheaviatorasitkeepsthemachinewithitsheadtothewind，whichistheonlysafepositionforanovice.Forinitialeducationalpurposes，however，arudderisnotessentialastheglideswill，orshould，bemadeonlevelground，inmoderate，steadywindcurrents，andatamodestelevation.Theadditionofarudder，therefore，maywellbeleftuntiltheaviatorhasbecomereasonablyexpertinthemanagementofhismachine.
PuttingtheMachineTogether.
Havingobtainedthenecessarymaterial，thefirstmoveistohavetheribpiecessteamedandcurved.Thiscurvemaybeslight，about2inchesforthe4feet.Whilethisisbeingdonetheotherpartsshouldbecarefullyroundedsothesquareedgeswillbetakenoff.Thismaybedonewithsandpaper.Nextapplyacoatofshellac，andwhendryrubitdownthoroughlywithfinesandpaper.Whentheribsarecurvedtreattheminthesameway.
Laytwoofthelonghorizontalframepiecesonthefloor3feetapart.Betweentheseplacesixofthestrutpieces.Putoneateachend，andeach41/2feetputanother，leavinga2—footspaceinthecenter.Thiswillgiveyoufourstruts41/2feetapart，andtwointhecenter2feetapart，asshownintheillustration.Thismakesfiverectangles.Besurethatthepointsofcontactareperfect，andthatthestrutsareexactlyatrightangleswiththehorizontalframes.Thisisamostimportantfeaturebecauseifyourframe\"skews\"ortwistsyoucannotkeepitstraightintheair.Nowgluetheendsofthestrutstotheframepieces，usingplentyofglue，andnailonstripsthatwillholdtheframeinplacewhiletheglueisdrying.Thenextdaylashthejointstogetherfirmlywiththeshoethread，windingitasyouwouldtomendabrokengunstock，andovereachlayerputacoatingofglue.Thisdone，theotherframepiecesandstrutsmaybetreatedinthesameway，andyouwillthusgetthefoundationsforthetwoplanes.
AnotherWayofPlacingStruts.
Inthemachinesbuiltforprofessionaluseastrongerandmorecertainformofconstructionisdesired.Thisissecuredbytheplacingthestrutsforthelowerplaneundertheframepiece，andthosefortheupperplaneoverit，allowingthemineachinstancetocomeoutflushwiththeouteredgesoftheframepieces.Theyarethensecurelyfastenedwithatieplateorclampwhichpassesovertheendofthestrutandisboundfirmlyagainstthesurfaceoftheframepiecebytheeyeboltsofthestanchionsockets.
PlacingtheRibPieces.
Takeoneoftheframesandplaceonittheribs，withthearchedsideup，lettingoneendoftheribscomeflushwiththefrontedgeoftheforwardframe，andtheotherendprojectingaboutafootbeyondtherearframe.
Themanneroffasteningtheribstotheframepiecesisoptional.Insomecasestheyarelashedwithshoethread，andinothersclampedwithametalclampfastenedwith1/2—inchwoodscrews.Whereclampsandscrewsareusedcareshouldbetakentomakeslightholesinthewoodwithanawlbeforestartingthescrewssoastolessenanytendencytosplitthewood.Onthetopframe，twenty—oneribsplacedonefootapartwillberequired.Onthelowerframe，becauseoftheopeningleftfortheoperator’sbody，youwillneedonlytwenty.
JoiningtheTwoFrames.
Thetwoframesmustnowbejoinedtogether.Forthisyouwillneedtwenty—fouraluminumorironsocketswhichmaybepurchasedatafoundryorhardwareshop.
Thesesockets，asthenameimplies，provideareceptacleinwhichtheendofastanchionisfirmlyheld，andhaveflangeswithholesforeye—boltswhichholdthemfirmlytotheframepieces，andalsoservetoholdtheguywires.
Inadditiontotheseeye—boltholestherearetwoothersthroughwhichscrewsarefastenedintotheframepieces.
Onthefrontframepieceofthebottomplaneplacesixsockets，beginningattheendoftheframe，andlocatingthemexactlyoppositethestruts.Screwthesocketsintopositionwithwoodscrews，andthenputtheeye—boltsinplace.Repeattheoperationontherearframe.Nextputthesocketsfortheupperplaneframeinplace.
Youarenowreadytobringthetwoplanestogether.
Beginbyinsertingthestanchionsinthesocketsinthelowerplane.Theendsmayneedalittlerubbingwithsandpapertogetthemintothesockets，butcaremustbetakentohavethemfitsnugly.Whenallthestanchionsareinplaceonthelowerplane，lifttheupperplaneintoposition，andfitthesocketsovertheupperendsofthestanchions.
TrussingwithGuyWires.
Thenextmoveisto\"tie\"theframetogetherrigidlybytheaidofguywires.ThisiswheretheNo.12pianowirecomesin.Eachrectangleformedbythestrutsandstanchionswiththeexceptionofthesmallcenterone，istobewiredseparatelyasshownintheillustration.
Ateachoftheeightcornersformingtherectangletheringofoneoftheeye—boltswillbefound.Therearetwowaysofdoingthis\"tieing，\"ortrussing.Oneistorunthewiresdiagonallyfromeye—bolttoeye—bolt，dependinguponmainstrengthtopullthemtautenough，andthentwisttheendssoastohold.Theotheristofirstmakealoopofwireateacheye—bolt，andconnecttheseloopstothemainwireswithturn—buckles.Thislattermethodisthebest，asitadmitsofthetensionbeingregulatedbysimplyturningthebucklesoastodrawtheendsofthewireclosertogether.Aglanceattheillustrationwillmakethisplain，andalsoshowhowthewiresaretobeplaced.Theproperdegreeoftensionmaybedeterminedinthefollowingmanner：
Aftertheframeiswiredplaceeachendonasaw—horsesoastolifttheentireframeclearofthework—shopfloor.Getunderit，inthecenterrectangleand，graspingthecenterstruts，oneineachhand，putyourentireweightonthestructure.Ifitisproperlyputtogetheritwillremainrigidandunyielding.Shoulditsageversoslightlythetensionofthewiresmustbeincreaseduntilanytendencytosag，nomatterhowslightitmaybe，isovercome.