flying machines-第29章

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aerodromics　seems；　then；　to　be；　that　while　it　is　not　likely

that　the　perfected　aerodrome　will　ever　be　able　to　dispense

altogether　with　the　ability　to　rely　at　intervals　on

some　internal　source　of　power；　it　will　not　be　indispensable

that　this　aerodrome　of　the　future　shall；　in　order　to

go　any　distanceeven　to　circumnavigate　the　globe　without

alightingneed　to　carry　a　weight　of　fuel　which

would　enable　it　to　perform　this　journey　under　conditions

analogous　to　those　of　a　steamship；　but　that　the　fuel　and

weight　need　only　be　such　as　to　enable　it　to　take　care　of

itself　in　exceptional　moments　of　calm。〃



Now　that　dynamic　flying　machines　have　been　evolved

and　are　being　brought　under　control；　it　seems　to　be

worth　while　to　make　these　computations　and　the　succeeding

explanations　known；　so　that　some　bold　man　will

attempt　the　feat　of　soaring　like　a　bird。　The　theory

underlying　the　performance　in　a　rising　wind　is　not　new；

it　has　been　suggested　by　Penaud　and　others；　but　it　has

attracted　little　attention　because　the　exact　data　and　the

maneuvers　required　were　not　known　and　the　feat　had

not　yet　been　performed　by　a　man。　The　puzzle　has　always

been　to　account　for　the　observed　act　in　very　light

winds；　and　it　is　hoped　that　by　the　present　selection　of

the　most　difficult　case　to　explaini。　e。；　the　soaring　in　a

dead　horizontal　calmsomebody　will　attempt　the　exploit。



Requisites　for　Soaring　Flights。



The　following　are　deemed　to　be　the　requisites　and

maneuvers　to　master　the　secrets　of　soaring　flight：



1stDevelop　a　dynamic　flying　machine　weighing

about　one　pound　per　square　foot　of　area；　with　stable

equilibrium　and　under　perfect　control；　capable　of　gliding

by　gravity　at　angles　of　one　in　ten　（5　3/4　degrees）　in　still　air。



2nd。Select　locations　where　soaring　birds　abound　and

occasions　where　rising　trends　of　gentle　winds　are　frequent

and　to　be　relied　on。



3rd。Obtain　an　initial　velocity　of　at　least　25　feet　per

second　before　attempting　to　soar。



4th。So　locate　the　center　of　gravity　that　the　apparatus

shall　assume　a　negative　angle；　fore　and　aft；　of　about　3　degrees。



Calculations　show；　however；　that　sufficient　propelling

force　may　still　exist　at　0　degrees；　but　disappears　entirely　at

＋4　degrees。



5th。Circle　like　the　bird。　Simultaneously　with　the

steering；　incline　the　apparatus　to　the　side　toward　which

it　is　desired　to　turn；　so　that　the　centrifugal　force　shall

be　balanced　by　the　centripetal　force。　The　amount　of　the

required　inclination　depends　upon　the　speed　and　on　the

radius　of　the　circle　swept　over。



6th。Rise　spirally　like　the　bird。　Steer　with　the

horizontal　rudder；　so　as　to　descend　slightly　when　going

with　the　wind　and　to　ascend　when　going　against　the

wind。　The　bird　circles　over　one　spot　because　the　rising

trends　of　wind　are　generally　confined　to　small　areas　or

local　chimneys；　as　pointed　out　by　Sir　H。　Maxim　and

others。



7th。Once　altitude　is　gained；　progress　may　be　made

in　any　direction　by　gliding　downward　by　gravity。



The　bird's　flying　apparatus　and　skill　are　as　yet　infinitely

superior　to　those　of　man；　but　there　are　indications　that

within　a　few　years　the　latter　may　evolve　more　accurately

proportioned　apparatus　and　obtain　absolute　control　over

it。



It　is　hoped；　therefore；　that　if　there　be　found　no　radical

error　in　the　above　computations；　they　will　carry　the　conviction

that　soaring　flight　is　not　inaccessible　to　man；　as

it　promises　great　economies　of　motive　power　in　favorable

localities　of　rising　winds。



The　writer　will　be　grateful　to　experts　who　may　point

out　any　mistake　committed　in　data　or　calculations；　and

will　furnish　additional　information　to　any　aviator　who

may　wish　to　attempt　the　feat　of　soaring。







CHAPTER　XXI。



FLYING　MACHINES　VS。　BALLOONS。



While　wonderful　success　has　attended　the　development

of　the　dirigible　（steerable）　balloon　the　most　ardent

advocates　of　this　form　of　aerial　navigation　admit　that　it

has　serious　drawbacks。　Some　of　these　may　be　described

as　follows：



Expense　and　Other　Items。



Great　Initial　Expense。The　modern　dirigible　balloon

costs　a　fortune。　The　Zeppelin；　for　instance；　costs　more

than　100；000　（these　are　official　figures）。



Expense　of　Inflation。Gas　evaporates　rapidly；　and　a

balloon　must　be　re…inflated；　or　partially　re…inflated；　every

time　it　is　used。　The　Zeppelin　holds　460；000　cubic　feet

of　gas　which；　even　at　1　per　thousand；　would　cost　460。



Difficulty　of　Obtaining　Gas。If　a　balloon　suddenly

becomes　deflated；　by　accident　or　atmospheric　conditions；

far　from　a　source　of　gas　supply；　it　is　practically　worthless。

Gas　must　be　piped　to　it；　or　the　balloon　carted　to

the　gas　housean　expensive　proceeding　in　either　event。



Lack　of　Speed　and　Control。



Lack　of　Speed。Under　the　most　favorable　conditions

the　maximum　speed　of　a　balloon　is　30　miles　an　hour。

Its　great　bulk　makes　the　high　speed　attained　by　flying

machines　impossible。



Difficulty　of　Control。While　the　modern　dirigible　balloon　is

readily　handled　in　calm　or　light　winds；　its　bulk

makes　it　difficult　to　control　in　heavy　winds。



The　Element　of　Danger。Numerous　balloons　have

been　destroyed　by　lightning　and　similar　causes。　One　of

the　largest　of　the　Zeppelins　was　thus　lost　at　Stuttgart

in　1908。



Some　Balloon　Performances。



It　is　only　a　matter　of　fairness　to　state　that；　under

favorable　conditions；　some　very　creditable　records　have

been　made　with　modern　balloons；　viz：



November　23d；　1907；　the　French　dirigible　Patrie；　travelled

187　miles　in　6　hours　and　45　minutes　against　a

light　wind。　This　was　a　little　over　28　miles　an　hour。



The　Clement…Bayard；　another　French　machine；　sold

to　the　Russian　government；　made　a　trip　of　125　miles　at

a　rate　of　27　miles　an　hour。



Zeppelin　No。　3；　carrying　eight　passengers；　and　having

a　total　lifting　capacity　of　5；500　pounds　of　ballast　in

addition　to　passengers；　weight　of　equipment；　etc。；　was

tested　in　October；　1906；　and　made　67　miles　in　2　hours

and　17　minutes；　about　30　miles　an　hour。



These　are　the　best　balloon　trips　on　record；　and　show

forcefully　the　limitations　of　speed；　the　greatest　being　not

over　30　miles　an　hour。



Speed　of　Flying　Machines。



Opposed　to　the　balloon　performances　we　have　flying

machine　trips　（of　authentic　records）　as　follows：



Bleriotmonoplanein　190852　miles　an　hour。



DelagrangeJune　22；　190810　1/2　miles　in　16　minutes；

approximately　42　miles　an　hour。



WrightsOctober；　1905the　machine　was　then　in　its

infancy24　miles　in　38　minutes；　approximately　44　miles

an　hour。　On　December　31；　1908；　the　Wrights　made　77

miles　in　2　hours　and　20　minutes。



Lambert；　a　pupil　of　the　Wrights；　and　using　a　Wright

biplane；　on　October　18；　1909；　covered　29。82　miles　in　49

minutes　and　39　seconds；　being　at　the　rate　of　36　miles

an　hour。　This　flight　was　made　at　a　height　of　1；312　feet。



LathamOctober　21；　1909made　a　short　flight；　about

11　minutes；　in　the　teeth　of　a　40　mile　gale；　at　Blackpool；

Eng。　He　used　an　Antoniette　monoplane；　and　the　official

report　says：　〃This　exhibition　of　nerve；　daring　and　ability

is　unparalled　in　the　history　of　aviation。〃



FarmanOctober　20；　1909was　in　the　air　for　1　hour；

32　min。；　16　seconds；　travelling　47　miles；　1；184　yards；　a

duration　record　for　England。



PaulhanJanuary　18；　190147　1/2　miles　at　the　rate　of

45　miles　an　hour；　maintaining　an　altitude　of　from　1；000

to　2；000　feet。



Expense　of　Producing　Gas。



Gas　is　indispensable　in　the　operation　of　dirigible　balloons；

and　gas　is　expensive。　Besides　this　it　is　not　always

possible　to　obtain　it　in　sufficient　quantities　even　in　large

cities；　as　the　supply　on　hand　is　generally　needed　for

regular　customers。　Such　as　can　be　had　is　either　water

or　coal　gas；　neither　of　which　is　as　efficient　in　lifting

power　as　hydrogen。



Hydrogen　is　the　lightest　and　consequently　the　most

buoyant　of　all　known　gases。　It　is　secured　commercially

by　treating　zinc　or　iron　with　dilute　sulp