flying machines-第28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！



as　the　engine；　but　for　half　an　hour's　flight　its　weight

would　be　unimportant。



Best　Means　of　Propulsion。



The　best　method　of　propulsion　was　by　the　screw；

which　acting　in　air　was　subject　to　much　the　same　conditions

as　obtained　in　marine　work。　Its　efficiency　depended

on　its　diameter　and　pitch　and　on　its　position；

whether　in　front　of　or　behind　the　body　propelled。　From

this　theory　of　dynamic　support；　Mr。　Lanchester　proceeded；

the　efficiency　of　each　element　of　a　screw　propeller

could　be　represented　by　curves　such　as　were　given

in　his　first　lecture　before　the　society；　and　from　these

curves　the　over…all　efficiency　of　any　proposed　propeller

could　be　computed；　by　mere　inspection；　with　a　fair　degree

of　accuracy。　These　curves　showed　that　the　tips　of

long…bladed　propellers　were　inefficient；　as　was　also　the

portion　of　the　blade　near　the　root。　In　actual　marine

practice　the　blade　from　boss　to　tip　was　commonly　of

such　a　length　that　the　over…all　efficiency　was　95　per　cent

of　that　of　the　most　efficient　element　of　it。



Advocates　Propellers　in　Rear。



From　these　curves　the　diameter　and　appropriate　pitch

of　a　screw　could　be　calculated；　and　the　number　of

revolutions　was　then　fixed。　Thus；　for　a　speed　of　80　feet

per　second　the　pitch　might　come　out　as　8　feet；　in　which

case　the　revolutions　would　be　600　per　minute；　which

might；　however；　be　too　low　for　the　motor。　It　was　then

necessary　either　to　gear　down　the　propeller；　as　was　done

in　the　Wright　machine；　or；　if　it　was　decided　to　drive　it

direct；　to　sacrifice　some　of　the　efficiency　of　the　propeller。

An　analogous　case　arose　in　the　application　of　the　steam

turbine　to　the　propulsion　of　cargo　boats；　a　problem　as

yet　unsolved。　The　propeller　should　always　be　aft；　so

that　it　could　abstract　energy　from　the　wake　current；　and

also　so　that　its　wash　was　clear　of　the　body　propelled。

The　best　possible　efficiency　was　about　70　per　cent；　and

it　was　safe　to　rely　upon　66　per　cent。



Benefits　of　Soaring　Flight。



There　was；　Mr。　Lanchester　proceeded；　some　possibility

of　the　aeronaut　reducing　the　power　needed　for　transport

by　his　adopting　the　principle　of　soaring　flight；　as

exemplified　by　some　birds。　There　were；　he　continued；　two

different　modes　of　soaring　flight。　In　the　one　the　bird

made　use　of　the　upward　current　of　air　often　to　be　found

in　the　neighborhood　of　steep　vertical　cliffs。　These　cliffs

deflected　the　air　upward　long　before　it　actually　reached

the　cliff；　a　whole　region　below　being　thus　the　seat　of

an　upward　current。　Darwin　has　noted　that　the　condor

was　only　to　be　found　in　the　neighborhood　of　such　cliffs。

Along　the　south　coast　also　the　gulls　made　frequent　use

of　the　up　currents　due　to　the　nearly　perpendicular　chalk

cliffs　along　the　shore。



In　the　tropics　up　currents　were　also　caused　by

temperature　differences。　Cumulus　clouds；　moreover；　were

nearly　always　the　terminations　of　such　up　currents　of

heated　air；　which；　on　cooling　by　expansion　in　the　upper

regions；　deposited　their　moisture　as　fog。　These　clouds

might；　perhaps；　prove　useful　in　the　future　in　showing

the　aeronaut　where　up　currents　were　to　he　found。　An…

other　mode　of　soaring　flight　was　that　adopted　by　the

albatross；　which　took　advantage　of　the　fact　that　the　air

moved　in　pulsations；　into　which　the　bird　fitted　itself；

being　thus　able　to　extract　energy　from　the　wind。

Whether　it　would　be　possible　for　the　aeronaut　to　employ

a　similar　method　must　be　left　to　the　future　to　decide。



Main　Difficulties　in　Aviation。



In　practical　flight　difficulties　arose　in　starting　and　in

alighting。　There　was　a　lower　limit　to　the　speed　at

which　the　machine　was　stable；　and　it　was　inadvisable　to

leave　the　ground　till　this　limit　was　attained。　Similarly；

in　alighting　it　was　inexpedient　to　reduce　the　speed　below

the　limit　of　stability。　This　fact　constituted　a　difficulty

in　the　adoption　of　high　speeds；　since　the　length　of　run

needed　increased　in　proportion　to　the　square　of　the

velocity。　This　drawback　could；　however；　be　surmounted

by　forming　starting　and　alighting　grounds　of　ample　size。

He　thought　it　quite　likely　in　the　future　that　such　grounds

would　be　considered　as　essential　to　the　flying　machine

as　a　seaport　was　to　an　ocean…going　steamer　or　as　a　road

was　to　the　automobile。



Requisites　of　Flying　Machine。



Flying　machines　were　commonly　divided　into　monoplanes

and　biplanes；　according　as　they　had　one　or　two

supporting　surfaces。　The　distinction　was　not；　however；

fundamental。　To　get　the　requisite　strength　some　form

of　girder　framework　was　necessary；　and　it　was　a　mere

question　of　convenience　whether　the　supporting　surface

was　arranged　along　both　the　top　and　the　bottom　of　this

girder；　or　along　the　bottom　only。　The　framework　adopted

universally　was　of　wood　braced　by　ties　of　pianoforte

wire；　an　arrangement　giving　the　stiffness　desired　with

the　least　possible　weight。　Some　kind　of　chassis　was　also

necessary。







CHAPTER　XXIII。



AMATEURS　MAY　USE　WRIGHT　PATENTS。



Owing　to　the　fact　that　the　Wright　brothers　have　enjoined

a　number　of　professional　aviators　from　using

their　system　of　control；　amateurs　have　been　slow　to

adopt　it。　They　recognize　its　merits；　and　would　like　to

use　the　system；　but　have　been　apprehensive　that　it

might　involve　them　in　litigation。　There　is　no　danger

of　this；　as　will　be　seen　by　the　following　statement　made

by　the　Wrights：



What　Wright　Brothers　Say。



〃Any　amateur；　any　professional　who　is　not　exhibiting

for　money；　is　at　liberty　to　use　our　patented　devices。

We　shall　be　glad　to　have　them　do　so；　and　there　will　be

no　interference　on　our　part；　by　legal　action；　or　otherwise。

The　only　men　we　proceed　against　are　those　who；　without

our　permission；　without　even　asking　our　consent；

coolly　appropriate　the　results　of　our　labors　and　use　them

for　the　purpose　of　making　money。　Curtiss；　Delagrange；

Voisin；　and　all　the　rest　of　them　who　have　used　our

devices　have　done　so　in　money…making　exhibitions。　So

long　as　there　is　any　money　to　be　made　by　the　use　of　the

products　of　our　brains；　we　propose　to　have　it　ourselves。

It　is　the　only　way　in　which　we　can　get　any　return　for

the　years　of　patient　work　we　have　given　to　the　problem

of　aviation。　On　the　other　hand；　any　man　who　wants

to　use　these　devices　for　the　purpose　of　pleasure；　or　the

advancement　of　science；　is　welcome　to　do　so；　without

money　and　without　price。　This　is　fair　enough；　is　it　not？〃



Basis　of　the　Wright　Patents。



In　a　flying　machine　a　normally　flat　aeroplane　having

lateral　marginal　portions　capable　of　movement　to　different

positions　above　or　below　the　normal　plane　of　the

body　of　the　aeroplane；　such　movement　being　about　an

axis　transverse　to　the　line　of　flight；　whereby　said　lateral

marginal　portions　may　be　moved　to　different　angles　relatively

to　the　normal　plane　of　the　body　of　the　aeroplane；

so　as　to　present　to　the　atmosphere　different　angles

of　incidence；　and　means　for　so　moving　said　lateral　marginal

portions；　substantially　as　described。



Application　of　vertical　struts　near　the　ends　having

flexible　joints。



Means　for　simultaneously　imparting　such　movement

to　said　lateral　portions　to　different　angles　relatively　to

each　other。



Refers　to　the　movement　of　the　lateral　portions　on　the

same　side　to　the　same　angle。



Means　for　simultaneously　moving　vertical　rudder　so

as　to　present　to　the　wind　that　side　thereof　nearest　the

side　of　the　aeroplane　having　the　smallest　angle　of　incidence。



Lateral　stability　is　obtained　by　warping　the　end　wings

by　moving　the　lever　at　the　right　hand　of　the　operator；

connection　being　made　by　wires　from　the　lever　to　the

wing　tips。　The　rudder　may　also　be　curved　or　warped　in

similar　manner　by　lever　action。



Wrights　Obtain　an　Injunction。



In　January；　1910；　Judge　Hazel；　of　the　United　States

Circuit　Court；　granted　a　preliminary　injunction　restraining

the　Herring…Curtiss　Co。；　and　Glenn　H。　Curtiss；　from

manufacturing；　selling；　or　using　for　exhibition　purposes

the　machine　known　as　the　Curtiss　aeroplane。　The　injunction

was　obtained　on　the　ground　that　the　Curtiss

machine　is　an　infringement　upon　the　Wright　patents　in

the　matter　of　wing　warping　and　rudder　control。



It　is　not　the　purpose　of　the　authors　to　discuss　the

subject　pro　or　con。　Such　discussion　would　have　no　proper

place　in　a　volume　of　this　kind。　It　is　enough　to　say　that

Curtiss　stoutly　insists　that　his　machine　is　not　an

infringement　of　the　Wright　patents；　although　Judge　Hazel

evidently　thinks　differently。



What　the　Judge　Said。



In　granting　the　preliminary　injunction　the　judge　said：



〃Defendants　claim　generally　that　the　difference　in

construction　of　their　apparatus　causes　the　equilibrium　or

lateral　balance　to　be　maintained　and　its　aerial　movement

secured　upon　an　entirely　different　principle　from　that

of　complainant；　the　defendants'　aeroplanes　are　curved；

firmly　attached　to　the　stanchions　and　hence　are　incapable

of　twisti