the aeroplane speaks-第21部分

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LUBRICATION。Keep　all　moving　parts；　such　as　pulleys；　control　levers；　and　hinges　of　controlling　surfaces；　well　greased。


SPECIAL　INSPECTION。Apart　from　constantly　examining　the　aeroplane　with　reference　to　the　above　points　I　have　made；　I　think　that；　in　the　case　of　an　aeroplane　in　constant　use　it　is　an　excellent　thing　to　make　a　special　inspection　of　every　part；　say　once　a　week。　This　will　take　from　two　to　three　hours；　according　to　the　type　of　aeroplane。　In　order　to　carry　it　out　methodically；　the　rigger　should　have　a　list　of　every　part　down　to　the　smallest　split…pin。　He　can　then　check　the　parts　as　he　examines　them；　and　nothing　will　be　passed　over。　This；　I　know　from　experience；　greatly　increases　the　confidence　of　the　pilot；　and　tends　to　produce　good　work　in　the　air。


WINDY　WEATHER。The　aeroplane；　when　on　the　ground；　should　face　the　wind；　and　it　is　advisable　to　lash　the　control　lever　fast；　so　that　the　controlling　surfaces　may　not　be　blown　about　and　possibly　damaged。


‘‘VETTING''　BY　EYE。This　should　be　practiced　at　every　opportunity；　and；　if　persevered　in；　it　is　possible　to　become　quite　expert　in　diagnosing　by　eye　faults　in　flight　efficiency；　stability　and　control。

The　aeroplane　should　be　standing　upon　level　ground；　or；　better　than　that；　packed　up　into　its　‘‘flying　position。''

Now　stand　in　front　of　it　and　line　up　the　leading　edge　with　the　main　spar；　rear　spar；　and　trailing　edge。　Their　shadows　can　usually　be　seen　through　the　fabric。　Allowance　must；　of　course；　be　made　for　wash…in　and　wash…out；　otherwise；　the　parts　I　have　specified　should　be　parallel　with　each　other。

Now　line　up　the　centre　part　of　the　main…plane　with　the　tail…plane。　The　latter　should　be　horizontal。

Next；　sight　each　interplane　front　strut　with　its　rear　strut。　They　should　be　parallel。

Then；　standing　on　one　side　of　the　aeroplane；　sight　all　the　front　struts。　The　one　nearest　to　you　should　cover　all　the　others。　This　applies　to　the　rear　struts　also。

Look　for　distortion　of　leading　edges；　main　and　rear　spars；　trailing　edges；　tail…plane　and　controlling　surfaces。

This　sort　of　thing；　if　practiced　constantly；　will　not　only　develop　an　expert　eye　for　diagnosis　of　faults；　but　will　also　greatly　assist　in　impressing　upon　the　memory　the　characteristics　and　possible　troubles　of　the　various　types　of　aeroplanes。


MISHANDLING　OF　THE　GROUND。This　is　the　cause　of　a　lot　of　unnecessary　damage。　The　golden　rule　to　observe　is：　PRODUCE　NO　BENDING　STRESSES。

Nearly　all　the　wood　in　an　aeroplane　is　designed　to　take　merely　the　stress　of　direct　compression；　and　it　cannot　be　bent　safely。　Therefore；　in　packing　an　aeroplane　up　from　the　ground；　or　in　pulling　or　pushing　it　about；　be　careful　to　stress　it　in　such　a　way　as　to　produce；　as　far　as　possible；　only　direct　compression　stresses。　For　instance；　if　it　is　necessary　to　support　the　lifting　surface；　then　the　packing　should　be　arranged　to　come　directly　under　the　struts　so　that　they　may　take　the　stress　in　the　form　of　compression　for　which　they　are　designed。　Such　supports　should　be　covered　with　soft　packing　in　order　to　prevent　the　fabric　from　becoming　damaged。

When　pulling　an　aeroplane　along；　if　possible；　pull　from　the　top　of　the　undercarriage　struts。　If　necessary　to　pull　from　elsewhere；　then　do　so　by　grasping　the　interplane　struts　as　low　down　as　possible。

Never　lay　fabric…covered　parts　upon　a　concrete　floor。　Any　slight　movement　will　cause　the　fabric　to　scrape　over　the　floor　with　resultant　damage。

Struts；　spars；　etc。；　should　never　be　left　about　the　floor；　as　in　such　position　they　are　likely　to　become　scored。　I　have　already　explained　the　importance　of　protecting　the　outside　fibres　of　the　wood。　Remember　also　that　wood　becomes　distorted　easily。　This　particularly　applies　to　interplane　struts。　If　there　are　no　proper　racks　to　stand　them　in；　then　the　best　plan　is　to　lean　them　up　against　the　wall　in　as　near　a　vertical　position　as　possible。


TIME。Learn　to　know　the　time　necessary　to　complete　any　of　the　various　rigging　jobs。　This　is　really　important。　Ignorance　of　this　will　lead　to　bitter　disappointments　in　civil　life；　and；　where　Service　flying　is　concerned；　it　will；　to　say　the　least　of　it；　earn　unpopularity　with　senior　officers；　and　fail　to　develop　respect　and　good　work　where　men　are　concerned。


THE　AEROPLANE　SHED。This　should　be　kept　as　clean　and　orderly　as　possible。　A　clean；　smart　shed　produces　briskness；　energy；　and　pride　of　work。　A　dirty；　disorderly　shed　nearly　always　produces　slackness　and　poor　quality　of　work；　lost　tools　and　mislaid　material。


GLOSSARY

AeronauticsThe　science　of　aerial　navigation。

AerofoilA　rigid　structure；　of　large　superficial　area　relative　to　its　thickness；　designed　to　obtain；　when　driven　through　the　air　at　an　angle　inclined　to　the　direction　of　motion；　a　reaction　from　the　air　approximately　at　right　angles　to　its　surface。　Always　cambered　when　intended　to　secure　a　reaction　in　one　direction　only。　As　the　term　‘‘aerofoil''　is　hardly　ever　used　in　practical　aeronautics；　I　have；　throughout　this　book；　used　the　term　SURFACE；　which；　while　academically　incorrect；　since　it　does　not　indicate　thickness；　is　a　term　usually　used　to　describe　the　cambered　lifting　surfaces；　i。e。；　the　‘‘planes''　or　‘‘wings；''　and　the　stabilizers　and　the　controlling　aerofoils。

AerodromeThe　name　usually　applied　to　a　ground　used　for　the　practice　of　aviation。　It　really　means　‘‘flying　machine；''　but　is　never　used　in　that　sense　nowadays。

AeroplaneA　power…driven　aerofoil　with　stabilizing　and　controlling　surfaces。

AccelerationThe　rate　of　change　of　velocity。

Angle　of　IncidenceThe　angle　at　which　the　‘‘neutral　lift　line''　of　a　surface　attacks　the　air。

Angle　of　Incidence；　Rigger'sThe　angle　the　chord　of　a　surface　makes　with　a　line　parallel　to　the　axis　of　the　propeller。

Angle　of　Incidence；　MaximumThe　greatest　angle　of　incidence　at　which；　for　a　given　power；　surface　（including　detrimental　surface）；　and　weight；　horizontal　flight　can　be　maintained。

Angle　of　Incidence；　MinimumThe　smallest　angle　of　incidence　at　which；　for　a　given　power；　surface　（including　detrimental　surface）；　and　weight；　horizontal　flight　can　be　maintained。

Angle　of　Incidence；　Best　ClimbingThat　angle　of　incidence　at　which　an　aeroplane　ascends　quickest。　An　angle　approximately　halfway　between　the　maximum　and　optimum　angles。

Angle　of　Incidence；　OptimumThe　angle　of　incidence　at　which　the　lift…drift　ratio　is　the　highest。


Angle；　GlidingThe　angle　between　the　horizontal　and　the　path　along　which　an　aeroplane　at　normal　flying　speed；　but　not　under　engine　power；　descends　in　still　air。

Angle；　DihedralThe　angle　between　two　planes。

Angle；　Lateral　DihedralThe　lifting　surface　of　an　aeroplane　is　said　to　be　at　a　lateral　dihedral　angle　when　it　is　inclined　upward　towards　its　wing…tips。

Angle；　Longitudinal　DihedralThe　main　surface　and　tail　surface　are　said　to　be　at　a　longitudinal　dihedral　angle　when　the　projections　of　their　neutral　lift　lines　meet　and　produce　an　angle　above　them。

Angle；　Rigger's　Longitudinal　DihedralDitto；　but　substituting　‘‘chords''　for　‘‘neutral　life　lines。''

Angle；　PitchThe　angle　at　any　given　point　of　a　propeller；　at　which　the　blade　is　inclined　to　the　direction　of　motion　when　the　propeller　is　revolving　but　the　aeroplane　stationary。

AltimeterAn　instrument　used　for　measuring　height。

Air…Speed　IndicatorAn　instrument　used　for　measuring　air　pressures　or　velocities。　It　consequently　indicates　whether　the　surface　is　securing　the　requisite　reaction　for　flight。　Usually　calibrated　in　miles　per　hour；　in　which　case　it　indicates　the　correct　number　of　miles　per　hour　at　only　one　altitude。　This　is　owing　to　the　density　of　the　air　decreasing　with　increase　of　altitude　and　necessitating　a　greater　speed　through　space　to　secure　the　same　air　pressure　as　would　be　secured　by　less　speed　at　a　lower　altitude。　It　would　be　more　correct　to　calibrate　it　in　units　of　air　pressure。

Air　PocketA　local　movement　or　condition　of　the　air　causing　an　aeroplane　to　drop　or　lose　its　correct　attitude。

Aspect…RatioThe　proportion　of　span　to　chord　of　a　surface。

Air…Screw　（Propeller）A　surface　so　shaped　that　its　rotation　about　an　axis　produces　a　force　（thrust）　in　the　direction　of　its　axis。

AileronA　controlling　surface；　usually　situated　at　the　wing…tip；　the　operation　of　which　turns　an　aeroplane　about　its　longitudinal　axis；　causes　an　aeroplane　to　tilt　sideways。


AviationThe　art　of　driving　an　aeroplane。

AviatorThe　driver　of　an　aeroplane。

BarographA　recording　barometer；　the　charts　of　which　can　be　calibrated　for　showing　air　density　or　height。

BarometerAn　instrument　used　for　indicating　the　density　of　air。

Bank；　toTo　turn　an　aeroplane　about　its　longitudinal　axis　（to　tilt　sideways）　when　turning　to　left　or　right。

BiplaneAn　aeroplane　of　which　the　main　lifting　surface　consists　of　a　surface　or　pair　of　wings　mounted　above　another　surface　or　pair　of　wings。

BayThe　space　enclosed　by　two　struts　and　whatever　they　are　fixed　to。

BoomA　term　usually　applied　to　the　long　spars　joining　the　tail　of　a　‘‘pusher''　aeroplane　to　its　main　lifting　surface。

BracingA　system　of　struts　and　tie　wires　to　transfer　a　force　from　one　point　to　another。

CanardLiterally　‘‘duck。''　The　name　which　was　given　to　a　type　of　aeroplane　of　which　the　longitudinal　stabilizing　surface　（empennage）　was　mounted　in　front　of　the　main　lifting　surface。　Sometimes　termed　‘‘tail…first''　aeroplanes；　but　such　term　is　erroneous；　as　in　such　a　design　the　main　lifting　surface　acts　as；　and　is；　the　empennage。

CabreTo　fly　or　glide　at　an　excessive　angle　of　incidence；　tail　down。

CamberCurvature。

ChordUsually　taken　to　be　a　straight　line　between　the　trailing　and　leading　edges　of　a　surface。

CellThe　whole　of　the　lower　surface；　that　part　of　the　upper　surface　directly　over　it；　together　with　the　struts　and　wires　holding　them　together。

Centre　（Line）　of　PressureA　line　running　from　wing…tip　to　wing…tip；　and　through　which　all　the　air　forces　acting　upon　the　surface　may　be　said　to　act；　or　about　which　they　may　be　said　to　balance。

Centre　（Line）　of　Pressure；　ResultantA　line　transverse　to　the　longitudinal　axis；　and　the　position　of　which　is　the　resultant　of　the　centres　of　pressure　of　two　or　more　surfaces。

Centre　of　GravityThe　centre　of　weight。

CabaneA　combination　of　two　pylons；　situated　over　the　fuselage；　and　from　which　anti…li