the aeroplane speaks-第1部分

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The　Aeroplane　Speaks

by　H。　Barber
Captain；　Royal　Flying　Corps


DEDICATED　TO　THE　SUBALTERN　FLYING　OFFICER



MOTIVE

The　reasons　impelling　me　to　write　this　book；　the　maiden　effort　of　my　pen；　are；　firstly；　a　strong　desire　to　help　the　ordinary　man　to　understand　the　Aeroplane　and　the　joys　and　troubles　of　its　Pilot；　and；　secondly；　to　produce　something　of　PRACTICAL　assistance　to　the　Pilot　and　his　invaluable　assistant　the　Rigger。　Having　had　some　eight　years'　experience　in　designing；　building；　and　flying　aeroplanes；　I　have　hopes　that　the　practical　knowledge　I　have　gained　may　offset　the　disadvantage　of　a　hand　more　used　to　managing　the　‘‘joy…　stick''　than　the　dreadful　haltings；　the　many　side…slips；　the　irregular　speed；　and；　in　short；　the　altogether　disconcerting　ways　of　a　pen。

The　matter　contained　in　the　Prologue　appeared　in　the　Field　of　May　6th；　13th；　20th；　and　27th；　1916；　and　is　now　reprinted　by　the　kind　permission　of　the　editor；　Sir　Theodore　Cook。

I　have　much　pleasure　in　also　acknowledging　the　kindness　of　Mr。　C。　G。　Grey；　editor　of　the　Aeroplane；　to　whom　I　am　indebted　for　the　valuable　illustrations　reproduced　at　the　end　of　this　book。



CONTENTS

PROLOGUE

PART　I。　　　THE　ELEMENTARY　PRINCIPLES　AIR　THEIR　GRIEVANCES　II。　　THE　PRINCIPLES；　HAVING　SETTLED　THEIR　DIFFERENCES；　FINISH　THE　JOB　III。　THE　GREAT　TEST　IV。　　CROSS　COUNTRY　



CHAPTER　I。　　　FLIGHT　II。　　STABILITY　AND　CONTROL　III。　RIGGING　IV。　　PROPELLERS　　V。　　　MAINTENANCE



TYPES　OF　AEROPLANES

GLOSSARY




THE　AEROPLANE　SPEAKS

PROLOGUE

PART　I

THE　ELEMENTARY　PRINCIPLES　AIR　THEIR　GRIEVANCES

The　Lecture　Hall　at　the　Royal　Flying　Corps　School　for　Officers　was　deserted。　The　pupils　had　dispersed；　and　the　Officer　Instructor；　more　fagged　than　any　pupil；　was　out　on　the　aerodrome　watching　the　test　of　a　new　machine。

Deserted；　did　I　say？　But　not　so。　The　lecture　that　day　had　been　upon　the　Elementary　Principles　of　Flight；　and　they　lingered　yet。　Upon　the　Blackboard　was　the　illustration　you　see　in　the　frontispiece。

‘‘I　am　the　side　view　of　a　Surface；''　it　said；　mimicking　the　tones　of　the　lecturer。　‘‘Flight　is　secured　by　driving　me　through　the　air　at　an　angle　inclined　to　the　direction　of　motion。''

‘‘Quite　right；''　said　the　Angle。　‘‘That's　me；　and　I'm　the　famous　Angle　of　Incidence。''

‘‘And；''　continued　the　Surface；　‘‘my　action　is　to　deflect　the　air　downwards；　and　also；　by　fleeing　from　the　air　behind；　to　create　a　semi…vacuum　or　rarefied　area　over　most　of　the　top　of　my　surface。''

‘‘This　is　where　I　come　in；''　a　thick；　gruff　voice　was　heard；　and　went　on：　‘‘I'm　the　Reaction。　You　can't　have　action　without　me。　I'm　a　very　considerable　force；　and　my　direction　is　at　right…angles　to　you；''　and　he　looked　heavily　at　the　Surface。　‘‘Like　this；''　said　he；　picking　up　the　chalk　with　his　Lift；　and　drifting　to　the　Blackboard。

‘‘I　act　in　the　direction　of　the　arrow　R；　that　is；　more　or　less；　for　the　direction　varies　somewhat　with　the　Angle　of　Incidence　and　the　curvature　of　the　Surface；　and；　strange　but　true；　I'm　stronger　on　the　top　of　the　Surface　than　at　the　bottom　of　it。　The　Wind　Tunnel　has　proved　that　by　exhaustive　researchand　don't　forget　how　quickly　I　can　grow！　As　the　speed　through　the　air　increases　my　strength　increases　more　rapidly　than　you　might　thinkapproximately；　as　the　Square　of　the　Speed；　so　you　see　that　if　the　Speed　of　the　Surface　through　the　air　is；　for　instance；　doubled；　then　I　am　a　good　deal　more　than　doubled。　That's　because　I　am　the　result　of　not　only　the　mass　of　air　displaced；　but　also　the　result　of　the　Speed　with　which　the　Surface　engages　the　Air。　I　am　a　product　of　those　two　factors；　and　at　the　speeds　at　which　Aeroplanes　fly　to…day；　and　at　the　altitudes　and　consequent　density　of　air　they　at　present　experience；　I　increase　at　about　the　Square　of　the　Speed。

‘‘Oh；　I'm　a　most　complex　and　interesting　personality；　I　assure　youin　fact；　a　dual　personality；　a　sort　of　aeronautical　Dr。　Jekyll　and　Mr。　Hyde。　There's　Lift；　my　vertical　part　or　COMPONENT；　as　those　who　prefer　long　words　would　say；　he　always　acts　vertically　upwards；　and　hates　Gravity　like　poison。　He's　the　useful　and　admirable　part　of　me。　Then　there's　Drift；　my　horizontal　component；　sometimes；　though　rather　erroneously；　called　Head　Resistance；　he's　a　villain　of　the　deepest　dye；　and　must　be　overcome　before　flight　can　be　secured。''

‘‘And　I；''　said　the　Propeller；　‘‘I　screw　through　the　air　and　produce　the　Thrust。　I　thrust　the　Aeroplane　through　the　air　and　overcome　the　Drift；　and　the　Lift　increases　with　the　Speed　and　when　it　equals　the　Gravity　of　Weight；　thenthere　you　areFlight！　And　nothing　mysterious　about　it　at　all。''

‘‘I　hope　you'll　excuse　me　interrupting；''　said　a　very　beautiful　young　lady；　‘‘my　name　is　Efficiency；　and；　while　no　doubt；　all　you　have　said　is　quite　true；　and　that；　as　my　young　man　the　Designer　says；　‘You　can　make　a　tea…tray　fly　if　you　slap　on　Power　enough；'　I　can　assure　you　that　I'm　not　to　be　won　quite　so　easily。''

‘‘Well；''　eagerly　replied　the　Lift　and　the　Thrust；　‘‘let's　be　friends。　Do　tell　us　what　we　can　do　to　help　you　to　overcome　Gravity　and　Drift　with　the　least　possible　Power。　That　obviously　seems　the　game　to　play；　for　more　Power　means　heavier　engines；　and　that　in　a　way　plays　into　the　hands　of　our　enemy；　Gravity；　besides　necessitating　a　larger　Surface　or　Angle　to　lift　the　Weight；　and　that　increases　the　Drift。''

‘‘Very　well；''　from　Efficiency；　‘‘I'll　do　my　best；　though　I'm　so　shy；　and　I've　just　had　such　a　bad　time　at　the　Factory；　and　I'm　terribly　afraid　you'll　find　it　awefully　dry。''

‘‘Buck　up；　old　dear！''　This　from　several　new…comers；　who　had　just　appeared。　‘‘We'll　help　you；''　and　one　of　them；　so　lean　and　long　that　he　took　up　the　whole　height　of　the　lecture　room；　introduced　himself。

‘‘I'm　the　High　Aspect　Ratio；''　he　said；　‘‘and　what　we　have　got　to　do　to　help　this　young　lady　is　to　improve　the　proportion　of　Lift　to　Drift。　The　more　Lift　we　can　get　for　a　certain　area　of　Surface；　the　greater　the　Weight　the　latter　can　carry；　and　the　less　the　Drift；　then　the　less　Thrust　and　Power　required　to　overcome　it。　Now　it　is　a　fact　that；　if　the　Surface　is　shaped　to　have　the　greatest　possible　span；　i。e。；　distance　from　wing…tip　to　wing…tip；　it　then　engages　more　air　and　produces　both　a　maximum　Reaction　and　a　better　proportion　of　Lift　to　Drift。

‘‘That　being　so；　we　can　then　well　afford　to　lose　a　little　Reaction　by　reducing　the　Angle　of　Incidence　to　a　degree　giving　a　still　better　proportion　of　Lift　to　Drift　than　would　otherwise　be　the　case；　for　you　must　understand　that　the　Lift…Drift　Ratio　depends　very　much　upon　the　size　of　the　Angle　of　Incidence；　which　should　be　as　small　as　possible　within　certain　limits。　So　what　I　say　is；　make　the　surface　of　Infinite　Span　with　no　width　or　chord；　as　they　call　it。　That's　all　I　require；　I　assure　you；　to　make　me　quite　perfect　and　of　infinite　service　to　Miss　Efficiency。''

‘‘That's　not　practical　politics；''　said　the　Surface。　‘‘The　way　you　talk　one　would　think　you　were　drawing　L400　a　year　at　Westminster；　and　working　up　a　reputation　as　an　Aeronautical　Expert。　I　must　have　some　depth　and　chord　to　take　my　Spars　and　Ribs；　and　again；　I　must　have　a　certain　chord　to　make　it　possible　for　my　Camber　（that's　curvature）　to　be　just　right　for　the　Angle　of　Incidence。　If　that's　not　right　the　air　won't　get　a　nice　uniform　compression　and　downward　acceleration　from　my　underside；　and　the　rarefied　‘suction'　area　over　the　top　of　me　will　not　be　as　even　and　clean　in　effect　as　it　might　be。　That　would　spoil　the　Lift…Drift　Ratio　more　than　you　can　help　it。　Just　thrust　that　chalk　along；　will　you？　and　the　Blackboard　will　show　you　what　I　mean。''

‘‘Well；''　said　the　Aspect　Ratio；　‘‘have　it　your　own　way；　though　I'm　sorry　to　see　a　pretty　young　lady　like　Efficiency　compromised　so　early　in　the　game。''

‘‘Look　here；''　exclaimed　a　number　of　Struts；　‘‘we　have　got　a　brilliant　idea　for　improving　the　Aspect　Ratio；''　and　with　that　they　hopped　up　on　to　the　Spars。　‘‘Now；''　excitedly；　‘‘place　another　Surface　on　top　of　us。　Now　do　you　see？　There　is　double　the　Surface；　and　that　being　so；　the　proportion　of　Weight　to　Surface　area　is　halved。　That's　less　burden　of　work　for　the　Surface；　and　so　the　Spars　need　not　be　so　strong　and　so　deep；　which　results　in　not　so　thick　a　Surface。　That　means　the　Chord　can　be　proportionately　decreased　without　adversely　affecting　the　Camber。　With　the　Chord　decreased；　the　Span　becomes　relatively　greater；　and　so　produces　a　splendid　Aspect　Ratio；　and　an　excellent　proportion　of　Lift　to　Drift。''

‘‘I　don't　deny　that　they　have　rather　got　me　there；''　said　the　Drift；　‘‘but　all　the　same；　don't　forget　my　increase　due　to　the　drift　of　the　Struts　and　their　bracing　wires。''

‘‘Yes；　I　dare　say；''　replied　the　Surface；　‘‘but　remember　that　my　Spars　are　less　deep　than　before；　and　consequently　I　am　not　so　thick　now；　and　shall　for　that　reason　also　be　able　to　go　through　the　air　with　a　less　proportion　of　Drift　to　Lift。''

‘‘Remember　me　also；　please；''　croaked　the　Angle　of　Incidence。　‘‘Since　the　Surface　has　now　less　weight　to　carry　for　its　area；　I　may　be　set　at　a　still　lesser　and　finer　Angle。　That　means　less　Drift　again。　We　are　certainly　getting　on　splendidly！　Show　us　how　it　looks　now；　Blackboard。''　And　the　Blackboard　obligingly　showed　them　as　follows：

‘‘Well；　what　do　you　think　of　that？''　they　all　cried　to　the　Drift。

‘‘You　think　you　are　very　clever；''　sneered　the　Drift。　‘‘But　you　are　not　helping　Efficiency　as　much　as　you　think。　The　suction　effect　on　the　top　of　the　lower　Surface　will　give　a　downward　motion　to　the　air　above　it　and　the　result　will　be　that　the　bottom　of　the　top　Surface　will　not　secure　as　good　a　Reaction　from　the　air　as　would　otherwise　be　the　case；　and　that　means　loss　of　Lift；　and　you　can't　help　matters　by　increasing　the　gap　between　the　surfaces　because　that　means　longer　Struts　and　Wires；　and　that　in　itself　would　help　me；　not　to　speak　of　increasing　the　Weight。　You　see　it's　not　quite　so　easy　as　you　thought。''

At　this　moment　a　hiccough　was　heard；　and　a　rather　fast　and　rakish…looking　chap；　named　Stagger；　spoke　up。　‘‘How　d'ye　do；　miss；''　he　said　politely　to　Efficiency；　with　a　side　glance　out　of　his　wicked　old　eye。　‘‘I'm　a　bit　of　a　knut；　and　without　the　slightest　trouble　I　can　easily　minimize　the　disadvantage　that　old　reprobate　Drift　has　been　frightening　you　with。　I　just　stagger　the