aeroplanes-第14部分

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frame　operated　by　the　driver；　so　that　the　body

in　swinging　laterally　will　change　the　two　wings

at　the　same　time；　but　with　angles　in　different

directions。



THE　FARMAN　AILERONS。Farman's　disposition

is　somewhat　different；　as　shown　in　sketch　3。　The

wings　are　hinged　to　the　upper　planes　at　their　rear

edges；　and　near　the　extremities　of　the　planes。

Operating　wires　lead　to　a　lever　within　reach　of　the

aviator；　and；　by　this　means；　the　wings　are　held　at

any　desired　angle；　or　changed　at　will。



The　difficulty　of　using　any　particular　model；　is

true；　also；　of　the　arrangement　of　the　fore　and　aft

control；　as　well　as　the　means　for　laterally　stabilizing

it。　In　view　of　this　we　shall　submit　a　general

form；　which　may　be　departed　from　at　will。



FEATURES　WELL　DEVELOPED。Certain　features

are　fairly　well　developed；　however。　One　is　the

angle　of　the　supporting　plane；　with　reference　to

the　frame　itself；　and　the　other　is　the　height　at

which　the　tail　and　rudder　should　be　placed　above

the　surface　of　the　ground　when　the　machine　is　at

rest。



DEPRESSING　THE　REAR　END。This　latter　is　a

matter　which　must　be　taken　into　consideration；

because　in　initiating　flight　the　rear　end　of　the

frame　is　depressed　in　order　to　give　a　sufficient

angle　to　the　supporting　planes　so　as　to　be　able　to

inaugurate　flight。



In　order　to　commence　building　we　should　have

some　definite　idea　with　respect　to　the　power；　as

this　will；　in　a　measure；　determine　the　area　of　the

supporting　surfaces；　as　a　whole；　and　from　this

the　sizes　of　the　different　planes　may　be　determined。



DETERMINING　THE　SIZE。Suppose　we　decide　on

300　square　feet　of　sustaining　surface。　This　may

require　a　30；　a　40　or　a　50　horse　power　motor；

dependent　on　the　speed　required；　and　much　higher

power　has　been　used　on　that　area。



However；　let　us　assume　that　a　forty　horse　power

motor　is　available；　our　300　square　feet　of　surface

may　be　put　into　two　planes；　each　having　150　square

feet　of　surface；　which　would　make　each　5'　by　30'

in　size；　or；　it　may　be　decided　to　make　the　planes

narrower；　and　proportionally　longer。　This　is　immaterial。

The　shorter　the　planes　transversely；

the　greater　will　be　the　stability；　and　the　wider　the

planes　the　less　will　be　the　lift；　comparatively。



RULE　FOR　PLACING　THE　PLANES。The　rule　for

placing　the　planes　is　to　place　them　apart　a　distance

equal　to　the　width　of　the　planes　themselves；

so　that　if　we　decide　on　making　them　five　feet　wide；

they　should　be　placed　at　least　five　feet　apart。

This　rule；　while　it　is　an　admirable　one　for　slow

movements　or　when　starting　flight；　is　not　of　any

advantage　while　in　rapid　flight。



If　the　machine　is　made　with　front　and　rear

horizontally…disposed　rudders；　or　elevators；　they

also　serve　as　sustaining　surfaces；　which；　for　the

present　will　be　disregarded。



Lay　off　a　square　A；　Fig。　49a；　in　which　the　vertical

lines　B；　B；　and　the　horizontal　lines　C；　C；　are

5'　long；　and　draw　a　cross　D　within　this；　the　lines

running　diagonally　from　the　corners。



Now　step　off　from　the　center　cross　line　D；　three

spaces；　each　five　feet　long；　to　a　point　E；　and　join

this　point　by　means　of　upper　and　lower　bars　F；

G；　with　the　upper　and　lower　planes；　so　as　to　form

the　tail　frame。



_Fig。　49a。　Rule　for　spacing　Planes。_



As　shown　in　Fig。　50；　the　planes　should　now　be

indicated；　and　placed　at　an　angle　of　about　8　degrees

angle；　which　are　illustrated；　H　being　the

upper　and　I　the　lower　plane。　Midway　between　the

forward　edges　of　the　two　planes；　is　a　horizontal

line　J；　extending　forwardly；　and　by　stepping　off

the　width　of　two　planes；　a　point　K　is　made；　which

forms　the　apex　of　a　frame　L；　the　rear　ends　of　the

bars　being　attached　to　the　respective　planes　H；　I；

at　their　forward　edges。



_Fig。　50。　Frame　of　Control　Planes。_



_Fig。　51。　and　Fig。　52。_



ELEVATING　PLANES。We　must　now　have　the　general

side　elevation　of　the　frame；　the　planes；　their

angles；　the　tail　and　the　rudder　support；　and　the

frame　for　the　forward　elevator。



To　this　may　be　added　the　forward　elevating

plane　L；　the　rear　elevator；　or　tail　M；　and　the　vertical

steering　rudder　N。



The　frame　which　supports　the　structure　thus

described；　may　be　made　in　a　variety　of　ways；　the

object　being　to　provide　a　resilient　connection　for

the　rear　wheel　O。



Fig。　52　shows　a　frame　which　is　simple　in　construction

and　easily　attached。　The　lower　fore

and　aft　side　bars　P　have　the　single　front　wheel

axle　at　the　forward　end；　and　the　aft　double　wheels

at　the　rear　end；　a　flexible　bar　Q；　running　from　the

rear　wheel　axle　to　the　forward　end　of　the　lower

plane。



A　compression　spring　R　is　also　mounted　between

the　bar　and　rear　end　of　the　lower　plane　to

take　the　shock　of　landing。　The　forward　end　of

the　bar　P　has　a　brace　S　extending　up　to　the　front

edge　of　the　lower　plane；　and　another　brace　T　connects

the　bars　P；　S；　with　the　end　of　the　forwardly…

projecting　frame。



_Fig。　53。　Plan　view。_



The　full　page　view；　Fig。　53；　represents　a　plan

view；　with　one　of　the　wings　cut　away；　showing　the

general　arrangement　of　the　frame；　and　the　three

wheels　required　for　support；　together　with　the

brace　bars　referred　to。



The　necessity　of　the　rear　end　elevation　will

now　be　referred　to。　The　tail　need　not；　necessarily；

be　located　at　a　point　on　a　horizontal　line

between　the　planes。　It　may　be　higher；　or　lower

than　the　planes；　but　it　should　not　be　in　a　position

to　touch　the　ground　when　the　machine　is　about

to　ascend。



_Fig。　54。　Alighting。_



The　angle　of　ascension　in　the　planes　need　not

exceed　25　degrees　so　the　frame　does　not　require

an　angle　of　more　than　17　degrees。　This　is　shown

in　Fig。　54；　where　the　machine　is　in　a　position

ready　to　take　the　air　at　that　angle；　leaving　ample

room　for　the　steering　rudder。



ACTION　IN　ALIGHTING。Also；　in　alighting；　the

machine　is　banked；　practically　in　the　same

position　thus　shown；　so　that　it　alights　on　the　rear

wheels　O。



The　motor　U　is　usually　mounted　so　its　shaft　is

midway　between　the　planes；　the　propeller　V　being

connected　directly　with　the　shaft；　and　being　behind

the　planes；　is　on　a　medial　line　with　the

machine。



The　control　planes　L；　M；　N；　are　all　connected　up

by　means　of　flexible　wires　with　the　aviator　at　the

set　W；　the　attachments　being　of　such　a　character

that　their　arrangement　will　readily　suggest　themselves

to　the　novice。



THE　MONOPLANE。From　a　spectacular　standpoint

a　monoplane　is　the　ideal　flying　machine。　It

is　graceful　in　outline；　and　from　the　fact　that　it

closely　approaches　the　form　of　the　natural　flyer；

seems　to　be　best　adapted　as　a　type；　compared　with

the　biplane。



THE　COMMON　FLY。So　many　birds　have　been

cited　in　support　of　the　various　flying　theories　that

the　house　fly；　as　an　example　has　been　disregarded。

We　are　prone　to　overlook　the　small　insect；　but　it

is；　nevertheless；　a　sample　which　is　just　as　potent

to　show　the　efficiency　of　wing　surface　as　the　condor

or　the　vulture。



The　fly　has　greater　mobility　than　any　other　flying

creature。　By　the　combined　action　of　its　legs

and　wings　it　can　spring　eighteen　inches　in　the

tenth　of　a　second；　and　when　in　flight　can　change

its　course　instantaneously。



If　a　sparrow　had　the　same　dexterity；　proportionally；

it　could　make　a　flight　of　800　feet　in　the

same　time。　The　posterior　legs　of　the　fly　are　the

same　length　as　its　body；　which　enable　it　to　spring

from　its　perch　with　amazing　facility。



_Fig。　55。　Common　Fly。　Outstretched　Wings。_



The　wing　surface；　proportioned　to　its　body　and

weight；　is　no　less　a　matter　for　wonder　and　consideration。



In　Fig。　55　is　shown　the　outlines　of　the　fly　with

outstretched　wings。　Fig。　56　represents　it　with

the　wing　folded；　and　Fig。　57　is　a　view　of　a　wing

with　the　relative　size　of　the　top　of　the　body　shown

in　dotted　lines。



_Fig。　56。　Common　Fly。　Folded　Wings。_



The　first　thing　that　must　attract　attention；　after

a　careful　study　is　the　relative　size　of　the　body

and　wing　surface。　Each　wing　is　slightly　smaller

than　the　upper　surface　of　the　body；　and　the　thickness

of　the　body　is　equal　to　each　wing　spread。



_Fig。　57。　Relative　size　of　wing　and　body。_



The　weight；　compared　with　sustaining　surface；

if　expressed　in　understandable　terms；　would　be

equal　to　sixty　pounds　for　every　square　foot　of　surface。



STREAM　LINES。The　next　observation　is；　that

what　are　called　stream　lines　do　not　exist　in　the　fly。

Its　head　is　as　large　in　cross　section　as　its　body；

with　the　slightest　suggestion　only；　of　a　pointed

end。　Its　wings　are　perfectly　flat；　forming　a　true

plane；　not　dished；　or　provided　with　a　cambre；　even；

that　upward　curve；　or　bulge　on　the　top　of　the　aeroplane

surface；　which　seems　to　possess　such　a　fascination

for　many　bird　flight　advocates。



It　will　also　be　observed　that　the　wing　connection

with　the　body　is　forward　of　the　line　A；　which

represents　the　point　at　which　the　body　will　balance

itself；　and　this　line　passes　through　the　wings

so　that　there　is　an　equal　amount　of　supporting

surface　fore　and　aft　of　the　line。



Again；　the　wing　attachment　is　at　the　upper　side

of　the　body；　and　the　vertical　dimension　of　the

body；　or　its　thickness；　is　equal　to　four…fifths　of　the

length　of　he　wing。



The　wing　socket　permits　a　motion　similar　to　a

universal　joint；　Fig。　55　showing　how　the　inner

end　of　the　wing　has　a　downward　bend　where　it

joins　the　back；　as　at　B。



THE　MONOPLANE　FORM。For　the　purpose　of

making　comparisons　the　illustrations　of　the　monoplane

show　a　machine　of　300　square　feet　of　surface；

which　necessitates　a　wing　spread　of　forty

feet　from　tip　to　tip；　so　that　the　general　dimensions

of　each　should　be　18　1/2　feet　by　8　1/2　feet　at　its

widest　point。



First　draw　a　square　forty　feet　each　way；　as　in

Fig。　58；　and　through　this　make　a　horizontal　line

1；　and　four　intermediate　vertical　lines　are　then

drawn；　as　2；　3；　4；　5；　thus　providing　five