aeroplanes and dirigibles of war-第40章

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days　of　December。



While　the　exact　mechanism　of　this　missile　is　a　secret；　the

governing　principles　of　its　design　and　operation　are　known　to　a

select　few　technicians　in　this　country。　　Strange　to　say；　the

projectile　was　designed　in　the　first　instance　in　the　interests　of

peace　and　humanty；　but　while　engaged　upon　his　experiments　the

inventor　suddenly　concluded　that　it　would　be　a　more　profitable

asset　if　devoted　to　the　grim　game　of　war。　　At　the　time　the

military　significance　of　the　airship　and　the　aeroplane　were

becoming　apparent；　hence　the　sudden　diversion　of　the　idea　into　a

destructive　channel。



This　aerial　torpedo　is　a　small　missile　carrying　a　charge　of　high

explosive；　such　as　trinitrotoluene；　and　depends　for　its

detonation　upon　impact　or　a　time　fuse。　　It　is　launched　into　the

air　from　a　cradle　in　the　manner　of　the　ordinary　torpedo；　but　the

initial　velocity　is　low。　　The　torpedo　is　fitted　with　its　own

motive　power；　which　comes　automatically　into　action　as　the

missile　climbs　into　the　air。　　This　self…contained　energy　is　so

devised　that　the　maximum　power　is　attained　before　the　missile　has

lost　the　velocity　imparted　in　the　first　instance；　the　result

being　that　it　is　able　to　continue　its　flight　in　a　horizontal

direction　from　the　moment　it　attains　the　highest　point　in　its

trajectory；　which　is　naturally　varied　according　to　requirements。　

But　there　is　no　secret　about　the　means　of　propulsion。　　The　body

is　charged　with　a　slow…burning　combustible；　in　the　manner　of　the

ordinary　rocket；　whereby　it　is　given　a　rapid　rotary　motion。



Furthermore　it　is　stated　to　be　fitted　with　a　small　gyroscope　in

the　manner　of　the　torpedo　used　in　the　seas；　for　the　purpose　of

maintaining　direction　during　flight；　but　upon　this　point　there　is

considerable　divergence　of　opinion　among　technicians；　the　general

idea　being　that　the　torpedo　depends　upon　an　application　of　the

principle　of　the　ordinary　rocket　rather　than　upon　a　small　engine

such　as　is　fitted　to　the　ordinary　torpedo。　　The　employment　of　a

slow　combustible　ensures　the　maintenance　of　the　missile　in　the

air　for　a　period　exceeding　that　of　the　ordinary　shell。　　It　is

claimed　by　the　Germans　that　this　projectile　will　keep　aloft　for

half…an…hour　or　more；　but　this　is　a　phantasy。　　Its　maintenance　of

flight　is　merely　a　matter　of　minutes。



The　belated　appearance　of　this　much…lauded　projectile　and　its

restricted　use　suggest　that　it　is　unreliable；　and　perhaps　no　more

effective　than　the　aerial　torpedo　which　appeared　in　the　United

States　during　the　Spanish…American　War；　and　proved　a　complete

failure。　　An　effective　and　reliable　means　of　combating　or

frustrating　a　dirigible　attack；　other　than　by　gun…fire　or　resort

to　the　drastic　remedy　of　ramming　the　enemy；　has　yet　to　be

devised。







CHAPTER　XVII

WIRELESS　IN　AVIATION



In　a　previous　chapter　the　various　methods　of　signalling　between

the　ground　and　the　airman　aloft　have　been　described。　　Seeing　that

wireless　telegraphy　has　made　such　enormous　strides　and　has

advanced　to　such　a　degree　of　perfection；　one　naturally　would

conclude　that　it　constitutes　an　ideal　system　of　communication

under　such　conditions　in　military　operations。



But　this　is　not　the　case。　　Wireless　is　utilised　only　to　a　very

limited　extent。　　This　is　due　to　two　causes。　　The　one　is　of　a

technical；　the　other　of　a　strategical　character。



The　uninitiated；　bearing　in　mind　the　comparative　ease　with　which

wireless　installations　may　be　established　at　a　relatively　small

expense；　would　not　unreasonably　think　that　no　serious

difficulties　of　a　technical　character　could　arise：　at　least　none

which　would　defy　solution。　　But　these　difficulties　exist　in　two

or　three　different　fields；　each　of　which　is　peculiarly　complex

and　demands　individual　treatment。



In　the　first　place；　there　is　the　weight　of　the　necessary

installation。　　In　the　case　of　the　dirigible　this　may　be　a

secondary　consideration；　but　with　the　aeroplane　it　is　a　matter　of

primary　and　vital　importance。　　Again；　under　present　conditions；

the　noise　of　the　motor　is　apt　to　render　the　intelligent

deciphering　of　messages　while　aloft　a　matter　of　extreme

difficulty；　especially　as　these　are　communicated　in　code。　　The

engine　noise　might　be　effectively　overcome　by　the　use　of　a

muffler　such　as；　is　used　with　automobiles；　but　then　there　is　the

further　difficulty　of　vibration。



This　problem　is　being　attacked　in　an　ingenious　manner。　　It　is

proposed　to　substitute　for　audible　signals　visual

interpretations；　by　the　aid　of　an　electric　lamp；　the　fluctuations

in　which　would　correspond　to　the　dots　and　dashes　of　the　Morse

code。　　Thus　the　airman　would　read　his　messages　by　sight　instead

of　by　sound。



This　method；　however；　is　quite　in　its　infancy；　and　although

attractive　in　theory　and　fascinating　as　a　laboratory　experiment

or　when　conducted　under　experimental　conditions；　it　has　not

proved　reliable　or　effective　in　aeronautical　operations。　　But　at

the　same　time　it　indicates　a　promising　line　of　research　and

development。



Then　there　are　the　problems　of　weight　and　the　aerial。　　So　far　as

present　knowledge　goes；　the　most　satisfactory　form　of　aerial　yet

exploited　is　that　known　as　the　trailing　wire。　　From　300　to　700

feet　of　wire　are　coiled　upon　a　reel；　and　when　aloft　this　wire　is

paid　out　so　that　it　hangs　below　the　aeroplane。　　As　a　matter　of

fact；when　the　machine　is　travelling　at　high　speed　it　trails

horizontally　astern；　but　this　is　immaterial。　　One　investigator；

who　strongly　disapproves　of　the　trailing　aerial；　has　carried　out

experiments　with　a　network　of　wires　laid　upon　and　attached　to　the

surface　of　the　aeroplane's　wings。　　But　the　trailing　wire　is

generally　preferred；　and　certainly　up　to　the　present　has　proved

more　satisfactory。



The　greatest　obstacle；　however；　is　the　necessary　apparatus。　　The

average　aeroplane　designed　for　military　duty　is　already　loaded　to

the　maximum。　　As　a　rule　it　carries　the　pilot　and　an　observer；　and

invariably　includes　a　light　arm　for　defence　against　an　aerial

enemy；　together　with　an　adequate　supply　of　ammunition；　while

unless　short　sharp　flights　are　to　be　made；　the　fuel　supply

represents　an　appreciable　load。　　Under　these　circumstances　the

item　of　weight　is　a　vital　consideration。　　It　must　be　kept　within

a　limit　of　100　pounds；　and　the　less　the　equipment　weighs　the　more

satisfactory　it　is　likely　to　prove；　other　things　being　equal。



The　two　most　successful　systems　yet　exploited　are　the　Dubilier

and　the　Rouget。　　The　former　is　an　American　invention；　the　latter

is　of　French　origin。　　Both　have　been　tested　by　the　British

Military　Aeronautical　Department；　and　the　French　authorities

have　subjected　the　French　system　to　rigorous　trials。　　Both

systems；　within　their　limitations；　have　proved　satisfactory。



The　outstanding　feature　of　the　Dubilier　system　is　the　production

of　sine　waves　of　musical　frequency　from　continuous　current；　thus

dispensing　with　the　rotary　converter。　　The　operating　principle　is

the　obtaining　of　a　series　of　unidirectional　impulses　by　a

condenser　discharge；　the　pulsating　currents　following　one　another

at　regular　intervals　at　a　frequency　of　500　impulses　per　second；

which　may　be　augmented　up　to　1；000　impulses　per　second。　　The

complete　weight　of　such　an　apparatus　is　40　pounds；　the　electric

generator；　which　is　no　larger　than　the　motor　used　for　driving　the

ordinary　table　ventilating　fan；　accounts　for　16　pounds　of　this

total。　　Under　test　at　sea；　upon　the　deck　of　a　ship；　a　range　of

250　miles　has　been　obtained。　　The　British　Government　carried　out

a　series　of　experiments　with　this　system；　using　a　small　plant

weighing　about　30　pounds；　with　which　communication　was　maintained

up　to　about　20　miles。



In　the　French　system　the　Reuget　transmitter　is　employed。　　The

apparatus；　including　the　dynamo；　which　is　extremely　small；　weighs

in　all　70　pounds。　　A　small　alternator　of　200　watts　and　100　volts

is　coupled　direct　to　the　aeroplane　motor；　a　new　clutch　coupler

being　employ