aeroplanes and dirigibles of war-第26章

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that；　relatively　speaking；　the　〃Archibald〃　offers　a　better　target

to　the　airman　than　the　aeroplane　offers　to　the　man　behind　the

anti…aircraft　gun　on　the　motor　below。　　A　few　well…placed　bombs

are　sufficient　to　induce　the　pursuers　to　cease　their　activities。　

Even　if　the　missiles　fail　to　strike　the　motor…car　itself　they　can

wreak　disaster　in　directly　by　rendering　the　road　impassable　or

dangerous　to　negotiate　at　high　speed。　　On　the　whole　therefore；

the　〃Archibald〃　is　a　greatly　exaggerated　weapon　of　offence

against　aircraft；　and；　so　far　as　is　known；　has　failed　to　fulfil

expectations。　　In　fact；　the　Germans　have　practically　abandoned

the　idea　of　using　it　in　the　manner　of　a　pursuing　arm；　they　work

the　weapon　as　a　fixture；　depending　upon　the　car　merely　as　a　means

of　moving　it　from　point　to　point。　　Thus；　in　reality；　it　has　been

converted　into　a　light　field…piece；　and　may　almost　be　included　in

the　category　of　fixed　weapons　for　combating　aerial　operations。







CHAPTER　XV

ANTI…AIRCRAFT　GUNS。　　IMMOBILE　WEAPONS



The　immobile　anti…aircraft　gun；　as　distinct　from　that　attached　to

a　travelling　carriage　such　as　a　motor…car；　may　be　subdivided　into

two　classes。　　The　one　is　the　fixed　arm　which　cannot　be　moved

readily；　mounted　upon　a　permanent　emplacement；　the　other　is　the

field…piece　which；　while　fired　from　a　stationary　position；　may　be

moved　from　point　to　point　upon　a　suitable　carriage。　　The

distinction　has　its　parallel　in　ordinary　artillery；　the

first…named　weapon　coinciding　with　the　heavy　siege　gun；　which　is

built　into　and　forms　part　and　parcel　of　the　defensive　or

offensive　scheme；　while　the　second　is　analogous　to　the　field

artillery；　which　may　be　wheeled　from　position　to　position。



In　this　phase　of　artillery　the　Germans　led　the　way；　for　the

simple　reason　that　they　recognised　the　military　value　of　aerial

navigation　years　in　advance　of　their　contemporaries。　　Again；　in

this　field　the　Krupp　Organisation　has　played　a　prominent　part。

It　embarked　upon　actual　construction　of　weapons　while　its　rivals

in　other　countries　were　content　to　prepare　their　drawings；　which

were　filed　against　〃The　Day。〃　　But　it　must　not　be　thought　that

because　the　German　manufacturers　of　armaments　were　ahead　of

their　contemporaries　they　dominated　the　situation。　　Far　from　it。　

Their　competitors　in　the　market　of　destruction　were　every　whit　as

keen；　as　ingenious；　and　as　enterprising。　　Kruppism　saw　a

commercial　opportunity　to　profit　from　advertisement　and　seized

it：　its　rivals　were　content　to　work　in　secret　upon　paper；　to　keep

pace　with　the　trend　of　thought；　and　to　perfect　their

organisations　so　as　to　be　ready　for　the　crisis　when　it　developed。



The　first　Krupp　anti…aircraft　field…piece　was　a　6。5　centimetre　（2


9/16　inch）　arm。　　It　possessed　many　interesting　features；　the　most

salient　of　which　was　the　design　of　the　axle　of　the　carriage。　　The

rigid　axle　for　the　two　wheels　was　replaced　by　an　axle　made　in　two

sections；　and　joined　together　in　the　form　of　a　universal

coupling；　so　that　each　wheel　virtually　possessed　its　own　axle；　or

rather　half…axle。　　This　was　connected　with　the　cradle　of　the　gun

in　such　a　manner　that　the　wheels　were　laterally　pivoted　thereon。



The　result　is　that　each　axle　can　be　turned　forward　together　with

its　wheel；　and　thus　the　wheels　have　their　rims　brought　into　line

to　form　an　arc　of　a　circle；　of　which　the　rear　end　of　the　spade　of

the　gun　carriage　constitutes　the　centre。　　This　acts　as　a　pivot；

about　which　the　gun　can　be　turned；　the　pair　of　wheels　forming　the

runners　for　the　achievement　of　this　movement。　　The　setting　of　the

weapon　in　the　firing　position　or　its　reversion　to　the　travelling

position　can　be　easily　and　speedily　effected　merely　by　the

rotation　of　a　handwheel　and　gearing。



With　this　gun　a　maximum　elevation　of　60　degrees　is　possible；

owing　to　the　trunnions　being　carried　well　behind　the　breech　in

combination　with　the　system　of　long　steady　recoil。　　The　balancing

spring　which　encloses　the　elevating　screw　is　contained　in　a

protected　box。　　The　recoil　brake；　together　with　the　spring

recuperator；　follows　the　usual　Krupp　practice　in　connection　with

ordinary　field　pieces；　as　does　also　the　automatic　breech…closing

and　firing　mechanism。　　In　fact　there　is　no　pronounced　deviation

from　theprevailing　Krupp　system；　and　only　such　modifications　as

are　necessary　to　adapt　the　arm　to　its　special　duty。　　When　the　gun

is　elevated　to　high　angles　the　shell；　after　insertioin　the

breech；　is　prevented　from　slipping　out　by　means　of　a　special

device；　so　that　the　proper　and　automatic　closing　of　the　breech　is

not　impaired　in　any　way。



In　such　an　arm　as　this；　which　is　designed　essentially　for

high…angle　firing；　the　sighting　and　training　facilities　require

to　be　carried　out　upon　special　lines；　inasmuch　as　the　objective

is　necessarily　at　a　considerable　altitude　above　the　horizon　of

the　gun。　　In　other　words；　in　firing　at　a　high　inclination；

distance　between　the　gun　and　the　target　cannot　be　utilised

directly　for　the　back　sight。　　On　the　other　hand；　it　is　essential

that　in　proportion　as　the　angle　from　the　horizontal　increases；

the　back　sight　should　be　lowered　progressively　in　a　manner

corresponding　to　the　distance。



To　assist　the　range…finder　in　his　task　of　sighting　it　is

necessary　that　he　should　be　provided　with　firing　tables　set　out

in　a　convenient　form；　which；　in　conjunction　with　the　telemeter；

serve　to　facilitate　training　for　each　successive　round。　　In　this

way　it　is　possible　to　pick　up　the　range　quickly　and　to　keep　the

objective　in　the　line　of　fire　until　it　either　has　been　put　hors

de　combat；　or　has　succeeded　in　retiring　beyond　the　range　of　the

gun。



The　sighting　arrangements　of　these　Krupp　anti…aircraft　guns　are

carried　out　upon　these　lines。　　Beneath　the　barrel　of　the

back…sight　is　an　observing　glass　with　an　eye…piece　for　the

artillerist；　while　above　and　behind　the　observing　glass　is

another　eye…piece；　to　be　used　in　conjunction　with　the

manipulation　of　the　back…sight。　　The　eye…piece　of　the　observation

glass　is　so　made　that　it　can　be　turned　through　a　vertical　plane

in　proportion　as　the　angle　of　fire　increases　in　relation　to　the

horizontal。　　The　determination　of　the　distance　from　the　objective

and　from　the　corresponding　back…sight　as　well　as　the　observation

of　the　altitude　is　carried　out　with　the　aid　of　the　telemeter。　

This　again　carries　an　observation　glass　fitted　with　an　eye…piece

which　can　be　turned　in　the　vertical　plane　in　the　same　manner　as

that　of　the　fore…sight。　　By　means　of　this　ingenious　sighting

device　it　is　possible　to　ascertain　the　range　and　angle　of　fire

very　easily　and　speedily。



The　weight　of　the　special　Krupp　anti…aircraft　field…piece；

exclusive　of　the　protecting　shield；　is　approximately　identical

with　that　of　the　ordinary　light　artillery　field…piece。　　It　throws

a　shell　weighing　8。8　pounds　with　an　initial　velocity　of　about

2；066　feet　per　second。



Although　the　German　armament　manufacturers　were　among　the　first

to　enter　the　field　with　an　anti…aircraft　gun　of　this　character

they　were　speedily　followed　by　the　French；　who　devised　a　superior

weapon。　　In　fact；　the　latter　represented　such　a　decisive　advance

that　the　German　artillerists　did　　not　hesitate　to　appropriate

their　improvements　in　sundry　essential　details；　and　to

incorporate　them　with　their　own　weapons。　　This　applies　especially

to　the　differential　recoil　system　which　is　utilised　in　the　small

anti…aircraft　guns　now　mounted　upon　the　roofs　of　high　buildings

of　cities　throughout　Germany　for　the　express　purpose　of　repelling

aerial　attack。



The　French　system　is　admitted　by　the　leading　artillery

technicians　of　the　world　to　be　the　finest　which　has　ever　been

designed；　its　remarkable　success　being　due　to　the　fact　that　it

takes　advantage　of　the　laws　of　Nature。　　In　this　system　the　gun　is

drawn　back　upon　its　cradle　preparatory　to　firing。　　In　some

instances　the　barrel　is　compressed　against　a　spring；　but　in　the

more　modern　guns　it　is　forced　to　rest　against　a　cushion　of

compressed　air　contained　within　a　cylinder。　　When　first　bringing

the　gun　into　action；　the　barrel　is　brought　into　the　preliminary

position　by　manually　compressing　the　air　or　spring　by　means　of　a

lever。　　Thereafter　the　gun　works　automatically。　　When　the　gun　is

fired　the　barrel　is　released　and　it　flies　forward。　　At　a　critical

point　in　its　forward　travel　the　charge　is　fired　and　the

projectile　speeds　on　its　way。　　The　kick　or　recoil　serves　to

arrest　the　forward　movement　of　the　barrel　and　finally　drives　it

back　again　against　the　strong　spring　or　cushion　of　compressed　air

within　the　cylinder　to　its　normal　position；　when　it　is　ready　for

the　introduction　of　the　next　shell。



The　outstanding　feature　of　this　system　is　that　the　projectile　is

given　a　higher　initial　velocity　than　is　possible　with　the　barrel

held　rigid　at　the　moment　of　discharge；　because　the　shell　is

already　travelling　at　the　moment　of　firing。



The　fixed　anti…aircraft　guns　such　as　are　stationed　upon　eminences

and　buildings　are　of　the　quick　firing　type；　the　object　being　to

hurl　a　steady；　con　tinuous　stream　of　missiles　upon　the　swiftly

moving　aeroplane。　　Some　of　the　weapons　throw　a　one…pound　shell

and　are　closely　similar　to　the　pom…pom　which　proved　so　effective

during　the　South　African　war。　　Machine　guns　also　have　been

extensively　adopted　for　this　duty　by　all　the　combatants；　their

range　of　approximately　2；000　yards　and　rapidity　of　fire　being

distinctly　valuable　when　hostile　aircraft　descend　to　an　altitude

which　brings　them　within　the　range　of　the　weapon。



The　greatest　difficulty　in　connection　with　this　phase　of

artillery；　however；　is　not　so　much　the　evolution　of　a　serviceable

and　efficient　type　of　gun；　as　the　determination　of　the　type　of

projectile　which　is　likely　to　be　most　effective。　　While　shrapnel

is　employed　somewhat　extensively　it　has　not　proved　completely

satisfactory。　　It　is　difficult　to　set　the　timing　fuse　even　after

the　range　has　been　found　approximately；　which　in　itself　is　no

easy　matter　when　the　aircraft　is　moving　rapidly　and　irregularly；

but　reliance　is　placed　thereon　in　the　hope　that　the　machine　may

happen　to　be　within　the　cone　of　dispersion　when　the　shell　bursts；

and　that　one　or　more　of　the　pieces　of　projectile　and　bullets　may

chance　to　penetrate　either　the　body　of　the　airman　or　a　vital　part

of　the　mechanism。



It　is　this　uncertainty　which　has　led　to　a　preference　for　a　direct

missile　such　as　the　bullet　discharged　from　a　machine　gun。　　A

stream　of　missiles；　even　of　rifle　calibre；　maintained　at　the　rate

of　some　400　shots　per　minute　is　certain　to　be　more　effective；

provided　range　and　aim　are　correct；　than　shrapnel。　　But　the

ordinary　rifle…bullet；　unless　the　objective　is　within　very　close

range；　is　not　likely　to　cause　much　harm；　at　least　not　to　the

mechanism　of　the　aerial　vessel。



It　is　for　this　reason　that　greater　attention　is　being　devoted；

especially　by　the　F