flying machines-第12章

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capacity。



In　the　Wright　machine；　in　which　there　is　a　lifting

capacity　of　approximately　2　1/4　pounds　to　the　square　foot

of　surface　area；　an　engine　of　only　25　horsepower　is　used。

In　the　Curtiss；　which　has　a　lifting　capacity　of　2　1/2

pounds　per　square　foot；　the　engine　is　of　50　horsepower。

This　is　another　of　the　peculiarities　of　aerial　construction

and　navigation。　Here　we　have　a　gain　of　1/4　pound　in

weight…lifting　capacity　with　an　expenditure　of　double

the　horsepower。　It　is　this　feature　which　enables　Curtiss

to　get　along　with　a　smaller　surface　area　of　supporting

planes　at　the　expense　of　a　big　increase　in　engine　power。

Proper　Weight　of　Machine。



As　a　general　proposition　the　most　satisfactory　machine

for　amateur　purposes　will　be　found　to　be　one　with

a　total　weight…sustaining　power　of　about　1；200　pounds。

Deducting　170　pounds　as　the　weight　of　the　operator；

this　will　leave　1；030　pounds　for　the　complete　motor…

equipped　machine；　and　it　should　be　easy　to　construct　one

within　this　limit。　This　implies；　of　course；　that　due　care

will　be　taken　to　eliminate　all　superfluous　weight　by　using

the　lightest　material　compatible　with　strength　and　safety。



This　plan　will　admit　of　686　pounds　weight　in　the

frame　work；　coverings；　etc。；　and　344　for　the　motor；

propeller；　etc。；　which　will　be　ample。　Just　how　to　distribute

the　weight　of　the　planes　is　a　matter　which　must

be　left　to　the　ingenuity　of　the　builder。



Comparison　of　Bird　Power。



There　is　an　interesting　study　in　the　accompanying

illustration。　Note　that　the　surface　area　of　the　albatross

is　much　smaller　than　that　of　the　vulture；　although　the

wing　spread　is　about　the　same。　Despite　this　the　albatross

accomplishes　fully　as　much　in　the　way　of　flight

and　soaring　as　the　vulture。　Why？　Because　the　albaboss　is　quicker

and　more　powerful　in　action。　It　is

the　application　of　this　same　principle　in　flying　machines

which　enables　those　of　great　speed　and　power　to　get

along　with　less　supporting　surface　than　those　of　slower

movement。



Measurements　of　Curtiss　Machine。



Some　idea　of　framework　proportion　may　be　had　from

the　following　description　of　the　Curtiss　machine。　The

main　planes　have　a　spread　（width）　of　29　feet；　and　are

4　1/2　feet　deep。　The　front　double　surface　horizontal　rudder

is　6x2　feet；　with　an　area　of　24　square　feet。　To　the

rear　of　the　main　planes　is　a　single　surface　horizontal

plane　6x2　feet；　with　an　area　of　12　square　feet。　In　connection

with　this　is　a　vertical　rudder　2　1/2　feet　square。

Two　movable　ailerons；　or　balancing　planes；　are　placed

at　the　extreme　ends　of　the　upper　planes。　These　are　6x2

feet；　and　have　a　combined　area　of　24　square　feet。　There

is　also　a　triangular　shaped　vertical　steadying　surface　in

connection　with　the　front　rudder。



Thus　we　have　a　total　of　195　square　feet；　but　as　the

official　figures　are　258；　and　the　size　of　the　triangular…

shaped　steadying　surface　is　unknown；　we　must　take　it

for　granted　that　this　makes　up　the　difference。　In　the

matter　of　proportion　the　horizontal　double…plane　rudder

is　about　one…tenth　the　size　of　the　main　plane；　counting

the　surface　area　of　only　one　plane；　the　vertical　rudder

one…fortieth；　and　the　ailerons　one…twentieth。







CHAPTER　XI。



PLANE　AND　RUDDER　CONTROL。



Having　constructed　and　equipped　your　machine；　the

next　thing　is　to　decide　upon　the　method　of　controlling

the　various　rudders　and　auxiliary　planes　by　which　the

direction　and　equilibrium　and　ascending　and　descending

of　the　machine　are　governed。



The　operator　must　be　in　position　to　shift　instantaneously　the

position　of　rudders　and　planes；　and　also　to　control

the　action　of　the　motor。　This　latter　is　supposed　to

work　automatically　and　as　a　general　thing　does　so　with

entire　satisfaction；　but　there　are　times　when　the　supply

of　gasolene　must　be　regulated；　and　similar　things　done。

Airship　navigation　calls　for　quick　action；　and　for　this

reason　the　matter　of　control　is　an　important　oneit　is

more　than　important；　it　is　vital。



Several　Methods　of　Control。



Some　aviators　use　a　steering　wheel　somewhat　after

the　style　of　that　used　in　automobiles；　and　by　this　not

only　manipulate　the　rudder　planes；　but　also　the　flow　of

gasolene。　Others　employ　foot　levers；　and　still　others；

like　the　Wrights；　depend　upon　hand　levers。



Curtiss　steers　his　aeroplane　by　means　of　a　wheel；　but

secures　the　desired　stabilizing　effect　with　an　ingenious

jointed　chair…back。　This　is　so　arranged　that　by　leaning

toward　the　high　point　of　his　wing　planes　the　aeroplane

is　restored　to　an　even　keel。　The　steering　post　of　the

wheel　is　movable　backward　and　forward；　and　by　this

motion　elevation　is　obtained。



The　Wrights　for　some　time　used　two　hand　levers；　one

to　steer　by　and　warp　the　flexible　tips　of　the　planes；　the

other　to　secure　elevation。　They　have　now　consolidated

all　the　functions　in　one　lever。　Bleriot　also　uses　the

single　lever　control。



Farman　employs　a　lever　to　actuate　the　rudders；　but

manipulates　the　balancing　planes　by　foot　levers。



Santos…Dumont　uses　two　hand　levers　with　which　to

steer　and　elevate；　but　manipulates　the　planes　by　means

of　an　attachment　to　the　back　of　his　outer　coat。



Connection　With　the　Levers。



No　matter　which　particular　method　is　employed；　the

connection　between　the　levers　and　the　object　to　be　manipulated

is　almost　invariably　by　wire。　For　instance；　from

the　steering　levers　（or　lever）　two　wires　connect　with　opposite

sides　of　the　rudder。　As　a　lever　is　moved　so　as　to

draw　in　the　right…hand　wire　the　rudder　is　drawn　to　the

right　and　vice　versa。　The　operation　is　exactly　the　same

as　in　steering　a　boat。　It　is　the　same　way　in　changing

the　position　of　the　balancing　planes。　A　movement　of

the　hands　or　feet　and　the　machine　has　changed　its

course；　or；　if　the　equilibrium　is　threatened；　is　back　on

an　even　keel。



Simple　as　this　seems　it　calls　for　a　cool　head；　quick

eye；　and　steady　hand。　The　least　hesitation　or　a　false

movement；　and　both　aviator　and　craft　are　in　danger。



Which　Method　is　Best？



It　would　be　a　bold　man　who　would　attempt　to　pick

out　any　one　of　these　methods　of　control　and　say　it　was

better　than　the　others。　As　in　other　sections　of　aeroplane

mechanism　each　method　has　its　advocates　who　dwell

learnedly　upon　its　advantages；　but　the　fact　remains　that

all　the　various　plans　work　well　and　give　satisfaction。



What　the　novice　is　interested　in　knowing　is　how　the

control　is　effected；　and　whether　he　has　become　proficient

enough　in　his　manipulation　of　it　to　be　absolutely　dependable

in　time　of　emergency。　No　amateur　should　attempt

a　flight　alone；　until　he　has　thoroughly　mastered

the　steering　and　plane　control。　If　the　services　and　advice　of　an

experienced　aviator　are　not　to　be　had　the

novice　should　mount　his　machine　on　some　suitable　supports

so　it　will　be　well　clear　of　the　ground；　and；　getting

into　the　operator's　seat；　proceed　to　make　himself　well

acquainted　with　the　operation　of　the　steering　wheel　and

levers。



Some　Things　to　Be　Learned。



He　will　soon　learn　that　certain　movements　of　the

steering　gear　produce　certain　effects　on　the　rudders。　If；

for　instance；　his　machine　is　equipped　with　a　steering

wheel；　he　will　find　that　turning　the　wheel　to　the　right

turns　the　aeroplane　in　the　same　direction；　because　the

tiller　is　brought　around　to　the　left。　In　the　same　way

he　will　learn　that　a　given　movement　of　the　lever　throws

the　forward　edge　of　the　main　plane　upward；　and　that　the

machine；　getting　the　impetus　of　the　wind　under　the　concave

surfaces　of　the　planes；　will　ascend。　In　the　same

way　it　will　quickly　become　apparent　to　him　that　an　opposite

movement　of　the　lever　will　produce　an　opposite

effectthe　forward　edges　of　the　planes　will　be　lowered；

the　air　will　be　〃spilled〃　out　to　the　rear；　and　the　machine

will　descend。



The　time　expended　in　these　preliminary　lessons　will

be　well　spent。　It　would　be　an　act　of　folly　to　attempt　to

actually　sail　the　craft　without　them。







CHAPTER　XII。



HOW　TO　USE　THE　MACHINE。



It　is　a　mistaken　idea　that　flying　machines　must　be

operated　at　extreme　altitudes。　True；　under　the　impetus

of　handsome　prizes；　and　the　incentive　to　advance　scientific

knowledge；　professional　aviators　have　ascended　to

considerable　heights；　flights　at　from　500　to　1；500　feet　being

now　common　with　such　experts　as　Farman；　Bleriot；

Latham；　Paulhan；　Wright　and　Curtiss。　The　altitude

record　at　this　time　is　about　4；165　feet；　held　by　Paulhan。



One　of　the　instructions　given　by　experienced　aviators

to　pupils；　and　for　which　they　insist　upon　implicit　obeyance；　is：

〃If　your　machine　gets　more　than　30　feet　high；

or　comes　closer　to　the　ground　than　6　feet；　descend　at

once。〃　Such　men　as　Wright　and　Curtiss　will　not　tolerate

a　violation　of　this　rule。　If　their　instructions　are

not　strictly　complied　with　they　decline　to　give　the　offender

further　lessons。



Why　This　Rule　Prevails。



There　is　good　reason　for　this　precaution。　The　higher

the　altitude　the　more　rarefied　（thinner）　becomes　the　air；

and　the　less　sustaining　power　it　has。　Consequently　the

more　difficult　it　becomes　to　keep　in　suspension　a　given

weight。　When　sailing　within　30　feet　of　the　ground　sustentation

is　comparatively　easy　and；　should　a　fall　occur；

the　results　are　not　likely　to　be　serious。　On　the　other

hand；　sailing　too　near　the　ground　is　almost　as　objectionable

in　many　ways　as　getting　up　too　high。　If　the　craft

is　navigated　too　close　to　the　ground　trees；　shrubs；　fences

and　other　obstructions　are　liable　to　be　encountered。

There　is　also　the　handicap　of　contrary　air　currents

diverted　by　the　obstructions　referred　to；　and　which　will

be　explained　more　fully　further　on。



How　to　Make　a　Start。



Taking　it　for　granted　that　the　beginner　has　familiarized

himself　with　the　manipulation　of　the　machine；　and　especially

the　control　mechanism；　the　next　thing　in　order

is　an　actual　flight。　It　is　probable　that　his　machine　will

be　equipped　with　a　wheeled　alighting　gear；　as　the　skids

used　by　the　Wrights　necessitate　the　use　of　a　special

starting　track。　In　this　respect　the　wheeled　machine　is

much　easier　to　handle　so　far　as　novices　are　concerned

as　it　may　be　easily　rolled　to　the　trial　grounds。　This；

as　in　the　case　of　the　initial　experiments；　should　be　a

clear；　reasonably　level　place；　free　from　trees；　fences；

rocks　and　similar　obstructions　with　which　there　may　be

danger　of　colliding。



The　beginner　will　need　the　assistance　of　three　men。

One　of　these　should　take　his　position　in　the　rear　of　the

machine；　and　one　at　each　end。　On　reaching　the　trial

ground　the　aviator　takes　his　seat　in　the　machine　and；

while　the　men　at　the　ends　hold　it　steady　the　one　in　the　rear

assists　in　retaining　it　until　the　operator　is　ready。　In　the

meantime　the　aviator　has　started　his　motor。　Like　the

glider　the　flying　machine；　in　order　to　accomplish　the

desired　results；　should　be　headed　into　the