flying machines-第15节

按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！



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　wind。



When　the　Machine　Rises。



Under　the　impulse　of　the　pushing　movement；　and　assisted

by　the　motor　action；　the　machine　will　gradually

rise　from　the　groundprovided　it　has　been　properly

proportioned　and　put　together；　and　everything　is　in　working

order。　This　is　the　time　when　the　aviator　requires

a　cool　head；　At　a　modest　distance　from　the　ground　use

the　control　lever　to　bring　the　machine　on　a　horizontal

level　and　overcome　the　tendency　to　rise。　The　exact

manipulation　of　this　lever　depends　upon　the　method　of

control　adopted；　and　with　this　the　aviator　is　supposed

to　have　thoroughly　familiarized　himself　as　previously

advised　in　Chapter　XI。



It　is　at　this　juncture　that　the　operator　must　act

promptly；　but　with　the　perfect　composure　begotten　of

confidence。　One　of　the　great　drawbacks　in　aviation　by

novices　is　the　tendency　to　become　rattled；　and　this　is

much　more　prevalent　than　one　might　suppose；　even

among　men　who；　under　other　conditions；　are　cool　and

confident　in　their　actions。



There　is　something　in　the　sensation　of　being　suddenly

lifted　from　the　ground；　and　suspended　in　the　air　that　is

disconcerting　at　the　start；　but　this　will　soon　wear　off　if

the　experimenter　will　keep　cool。　A　few　successful　flights

no　matter　how　short　they　may　be；　will　put　a　lot　of

confidence　into　him。



Make　Your　Flights　Short。



Be　modest　in　your　initial　flights。　Don't　attempt　to

match　the　records　of　experienced　men　who　have　devoted

years　to　mastering　the　details　of　aviation。　Paulhan；

Farman；　Bleriot；　Wright；　Curtiss；　and　all　the　rest　of

them　began；　and　practiced　for　years；　in　the　manner　here

described；　being　content　to　make　just　a　little　advancement

at　each　attempt。　A　flight　of　150　feet；　cleanly　and

safely　made；　is　better　as　a　beginning　than　one　of　400

yards　full　of　bungling　mishaps。



And　yet　these　latter　have　their　uses；　provided　the

operator　is　of　a　discerning　mind　and　can　take　advantage

of　them　as　object　lessons。　But；　it　is　not　well　to　invite

them。　They　will　occur　frequently　enough　under　the

most　favorable　conditions；　and　it　is　best　to　have　them

come　later　when　the　feeling　of　trepidation　and　uncertainty

as　to　what　to　do　has　worn　off。



Above　all；　don't　attempt　to　fly　too　high。　Keep　within

a　reasonable　distance　from　the　groundabout　25　or　30

feet。　This　advice　is　not　given　solely　to　lessen　the　risk

of　serious　accident　in　case　of　collapse；　but　mainly　because

it　will　assist　to　instill　confidence　in　the　operator。



It　is　comparatively　easy　to　learn　to　swim　in　shallow

water；　but　the　knowledge　that　one　is　tempting　death　in

deep　water　begets　timidity。



Preserving　the　Equilibrium。



After　learning　how　to　start　and　stop；　to　ascend　and

descend；　the　next　thing　to　master　is　the　art　of　preserving

equilibrium；　the　knack　of　keeping　the　machine　perfectly

level　in　the　airon　an　〃even　keel；〃　as　a　sailor　would

say。　This　simile　is　particularly　appropriate　as