aeroplanes and dirigibles of war-第33节

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inasmuch　as　even　should　the　bag　be　riddled　by　the　flying

fragments；　little　effective　damage　would　be　wroughtthe　craft

would　be　able　to　regain　its　haven。　　Accordingly　efforts　were

concentrated　upon　the　perfection　of　two　new　types　of　projectiles；

both　of　which　were　directed　more　particularly　against　the

dirigible。　　The　one　is　the　incendiary　shellobus　fumigenewhile

the　other　is　a　shell；　the　contents　of　which；　upon　coming　into

contact　with　the　gas　contained　within　the　gas…bag；　set　up　certain

chemical　reactions　which　precipitate　an　explosion　and　fire。



The　incendiary　shells　are　charged　with　a　certain　compound　which

is　ignited　by　means　of　a　fuse　during　its　flight。　　This　fuse

arrangement　coincides　very　closely　with　that　attached　to　ordinary

shrapnel；　inasmuch　as　the　timing　may　be　set　to　induce　ignition

at　different　periods；　such　as　either　at　the　moment　it　leaves　the

gun；　before；　or　when　it　strikes　the　envelope　of　the　dirigible。　

The　shell　is　fitted　with　a　〃tracer；〃　that　is　to　say；　upon

becoming　ignited　it　leaves　a　trail　of　smoke；　corresponding　with

the　trail　of　a　rocket；　so　that　its　passage　through　the　air　may　be

followed　with　facility。　　This　shell；　however；　was　designed　to

fulfil　a　dual。　　Not　only　will　it　fire　the　gaseous　contents　out　of

the　dirigible；　but　it　has　an　explosive　effect　upon　striking　an

incombustible　portion　of　the　aircraft；　such　as　the　machinery；

propellers　or　car；　when　it　will　cause　sufficient　damage　to　throw

the　craft　out　of　action。



The　elaborate　trials　which　were　carried　out　with　the　obus

fumigene　certainly　were　spectacular　so　as　they　went。　　Two　small

spherical　balloons；　10　feet　in　diameter；　and　attached　to　1；000

feet　of　cable；　were　sent　aloft。　　The　anti…aircraft　guns

themselves　were　placed　about　5；1OO　feet　distant。　　Owing　to　the

inclement　weather　the　balloons　were　unable　to　attain　a　height　of

more　than　200　feet　in　a　direct　vertical　line　above　the　ground。　

The　guns　were　trained　and　fired；　but　the　one　balloon　was　not　hit

until　the　second　round；　while　the　third　escaped　injury　until　the

fifth　round。　　When　struck　they　collapsed　instantly。　　Though　the

test　was　not　particularly　conclusive；　and　afforded　no　reliable

data；　one　point　was　ascertainedthe　trail　of　smoke　emitted　by

the　shell　enabled　its　trajectory　to　be　followed　with　ease。　　Upon

the　conclusion　of　these　trials；　which　were　the　most　successful

recorded；　quick…firing　tests　in　the　horizontal　plane　were　carried

out。　　The　best　performance　in　this　instance　was　the　discharge　of

five　rounds　in　eight　seconds。　　In　this　instance　the　paths　of　the

projectiles　were　simple　and　easy　to　follow；　the　flight　of　the

shell　being　observed　until　it　fell　some　18；670　feet　away。　　But

the　Krupp　firmhave　found　that　trials　upon　the　testing　ground　with

a　captive　balloon　differ　very　materially　from　sterntests　in　the

field　of　actual　warfare。　　Practically　nothing　has　been　heard　of

the　two　projectiles　during　this　war；　as　they　have　proved　an

absolute　failure。



Some　months　ago　the　world　was　startled　by　the　announcement　that

the　leading　German　armament　firm　had　acquired　the　whole　of　the

interest　in　an　aerial　torpedo　which　had　been　evolved　by　the

Swedish　artillerist；　Gustave　Unge；　and　it　was　predicted　that　in

the　next　war　widespread　havoc　would　be　wrought　therewith。　　

Remarkable　claims　were　advanced　for　this　projectile；　the　foremost

being　that　it　would　travel　for　a　considerable　distance　through

the　air　and　alight　upon　the　objective　with　infallible　accuracy。　　

The　torpedo　in　question　was　subjected　to　exacting　tests　in　Great

Britain；　which　failed　to　substantiate　all　the　claims　which　were

advanced；　and　it　is　significant　to　observe　that　little　has　been

heard　of　it　during　the　present　conflict。　　It　is　urged　in　certain

technical　quarters；　however；　that　the　aerial　torpedo　will　prove

to　be　the　most　successful　projectile　that　can　be　used　against

aircraft。　　I　shall　deal　with　this　question　in　a　later　chapter。



During　the　early　days　of　the　war　anti…aircraft　artillery　appeared

to　be　a　much　overrated　arm。　　The　successes　placed　to　its　credit

were　insignificant。　　This　was　due　to　the　artillerymen　being

unfamiliar　with　the　new　arm；　and　the　conditions　which　prevail

when　firing　into　space。　　Since　actual　practice　became　possible

great　advances　in　marksmanship　have　been　recorded；　and　the

accuracy　of　such　fire　to…day　is　striking。　　Fortunately　the　airman

possesses　the　advantage。　　He　can　manoeuvre　beyond　the　range　of

the　hostile　weapons。　　At　the　moment　10；000　feet　represents　the

extreme　altitude　to　which　projectiles　can　be　hurled　from　the　arms

of　this　character　which　are　now　in　use；　and　they　lack

destructiveness　at　that　range；　for　their　velocity　is　virtually

expended。



Picking　up　the　range　is　still　as　difficult　as　ever。　　The　practice

followed　by　the　Germans　serves　to　indicate　the　Teuton

thoroughness　of　method　in　attacking　such　problems　even　if　success

does　not　ensue。　　The　favourite　German　principle　of　disposing　

anti…aircraft　artillery　is　to　divide　the　territory　to　be

protected　into　equilateral　triangles；　the　sides　of　which　have　a

length　of　about　six　miles　or　less；　according　to　the　maximum

effective　range　of　the　pieces　at　an　elevation　of　23　1/2　degrees。



The　guns　are　disposed　at　the　corners　of　the　triangles　as

indicated　in　Figs。　13…14。　　Taking　the　one　triangle　as　an　example；

the　method　of　picking　up　the　range　may　be　explained　as　follows。　　

The　several　guns　at　the　comers　of　the　triangle；　each　of　which　can

be　trained　through　the　360　degrees　in　the　horizontal　plane；　are

in　telephonic　touch　with　an　observer　O　stationed　some　distance

away。　　The　airman　A　enters　the　area　of　the　triangle。　　The

observer　takes　the　range　and　communicates　with　the　gunner　B；　who

fires　his　weapon。　　The　shell　bursts　at　1　emitting　a　red　flame　and

smoke。　　The　observer　notes　the　altitude　and　relative　position　of

the　explosion　in　regard　to　the　aircraft；　while　gunner　B　himself

observes　whether　the　shell　has　burst　to　the　right　or　to　the　left

of　the　objective　and　corrects　accordingly。　　The　observer　commands

C　to　fire；　and　another　shell　is　launched　which　emits　a　yellow

flame　and　smoke。　　It　bursts　at　2　according　to　the　observer；　while

gunner　C　also　notes　whether　it　is　to　the　right　or　to　the　left　of

the　target　and　corrects　accordingly。　　Now　gunner　D　receives　the

command　to　fire　and　the　shell　which　explodes　at　3　throws　off　a

white　flame　and　smoke。　　Gunner　D　likewise　observes　whether　there

is　any　deviation　to　right　or　left　of　the　target　and　corrects　in　a

similar　manner。　　From　the　sum　of　the　three　rounds　the　observer

corrects　the　altitude；　completes　his　calculations；　and

communicates　his　instructions　for　correction　to　the　three

gunners；　who　now　merely　train　their　weapons　for　altitude。　　The

objective　is　to　induce　the　shells　hurled　from　the　three　corners

of　the　triangle　to　burst　at　a　common　point　4；　which　is　considered

to　be　the　most　critical　spot　for　the　aviator。　　The　fire　is　then

practically　concentrated　from　the　three　weapons　upon　the　apex　of

a　triangular　cone　which　is　held　to　bring　the　machine　within　the

danger　zone。



This　method　of　finding　the　range　is　carried　out　quicklytwo　or

three　seconds　being　occupied　in　the　task。　　In　the　early　days　of

the　war　the　German　anti…aircraft　artillerymen　proved　sadly

deficient　in　this　work；　but　practice　improved　their　fire　to　a

marvellous　degree；　with　the　result　that　at　the　moment　it　is

dangerous　for　an　aviator　to　essay　his　task　within　an　altitude　of

6；000　feet；　which　is　the　range　of　the　average　anti…aircraft　gun。



The　country　occupied　by　a　belligerent　is　divided　up　in　this

manner　into　a　series　of　triangles。　　For　instance；　a　machine

entering　hostile　territory　from　the　east；　enters　the　triangle

A…B…C；　and　consequently　comes　within　the　range　of　the　guns　posted

at　the　comers　of　the　triangle。　　Directly　he　crosses　the　line　B…C

and　enters　the　adjacent　triangle　he　passes　beyond　the　range　of

gun　A　but　comes　within　the　range　of　the　gun　posted　at　D；　and

while　within　the　triangular　area　is　under　fire　from　the　guns

B…C…D。　　He　turns　and　crosses　the　line　A…C；　but　in　so　doing　enters

another　triangle　A…C…E；　and　comes　range　of　the　gun　posted　at　E。



The　accompanying　diagram　represents　an　area　of　country　divided　up

into　such　triangle　and　the　position　of　the　guns；　while　the　circle

round　the　latter　indicate　the　training　arc　of　the　weapons；　each

of　which　is　a　complete　circle；　in　the　horizontal　plane。　　The

dotted　line　represents　the　aviator's　line　of　flight；　and　it　will

be　seen　that　no　matter　how　he　twists　and　turns　he　is　always

within　the　danger　zone　while　flying　over　hostile　territory。　　The

moment　he　outdistances　one　gun　he　comes　within　range　of　another。



The　safety　of　the　aviator　under　these　circumstances　depends　upon

his　maintaining　an　altitude　exceeding　the　range　of　the　guns

below；　the　most　powerful　of　which　have　a　range　of　8；000　to　10；000

feet；　or　on　speed　combined　with　rapid　twisting　and　turning；　or

erratic　undul