Report on the firing test to determine the limits of accuracy life of 4.7 A.A. gun T2

36 Pages·6.471 MB·English

by  Altshuler В.

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TROPRER EPORT .ONNO. 254
EHTENIMRETEDOTTSETGNIRIFEHTNOTROPRER EPORT ON THE FIR IN G TEST TO DETERM IN E THE STIMILL I MI TS O FO F
YCARUCCAA CCURACY EFLIL IFE .A.A"7.O4FO F 4.7" A.A. ZGTNUG UN T2
s.
by PROPERTY t)'F U. A].Ua.
STINFO BRAN~ 2~OOi
BEL. APG. •
B .B . reluhstAlA ltshuler
GOUNTEDIN
S rebmetpeS eptember 11941 941
si!hThiS tnemu?cod o~um~nt sa~h as nebeb een devorpapa pproved roffor cilbpup ublic esaerlerelease dnaa nd gelsas ale}
sitits noitubirtsidd Istribution sIiS .detimilunu njilllited.
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I i .Su.U .s. YMRAA RMY NEEDREBAA BERDEEN HCRAESERR ESEARCH DNAA ND TNEMPOLEVDED EVELOPMENT RETNCEC ENTER
CITSBILLAB ALLISTIC R HCRAESER ESEARCH SEIROTALROBAL ABORATORIES
NEEDREBAA BERDEEN GNIVOPRP ROVING ,DNUGORG ROUND, DNALYRAMM ARYLAND
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citsillaBBallistic hcraeseRResearch
yrota.robaLLaboratory tropeRReport .oNNo. 452254
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i .-- needrebAAberdeen gnivorPProving ,dnuorGGround, ,.dMMd., .
- .' .-,-----.--~"""'~--. --.- " . . i.: T . , -;. ..': __* " _ rebmetpeSSeptember ,011 .10.491 , 1941.
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TROPERREPORT EHTON ON THE GNIRIFFIRING TSETTEST OTTO ENIMRETEDDETERlUNE EHTTHE STIMILLIMITS FOOF YCARUCCAACCUHACY
EFILLIFE FOOF "7.44.7" .A.AA.A. GUN GUN 2TT2 _.
I, .
dn22nd tropeRReport noon ecnandrOOrdnance margorPProgram .oNNo. 00555500
setaDDates foof :tseTTest: lirpAApril 6226 otto tsuguAAugust ,99, .l1491 941.
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TCARTSBAABSTRACT I
eThT he eeffect ffect oof f etht he ffiring iring ono n vvarious arious estnemele lements oof f ehtt he cetelpmoc omplete dnuorr ound
-! dana nugnd gun eara re .detonn oted. -/$
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gnirDuD uring etht he llife ife oof, f etht he ,ngug un, ehtt he m elzzum uzzle vvelocity elocity sesaercded ecreases dana nd ehtt he
noisredpsid ispersion oof f m elzzum uzzle vvelocity elocity ,sesaeircni ncreases, aaffecting ffecting ehtt he ytilibaborpp robability oof f
,gnittihh itting. gnimuAssA ssuming etht he gnitatror otating dnabb and seunitcnoc ontinues t ot o ffunction, unction, ehtt he -uacca ccu
ycrar acy llife ife iis s e detamitse stimated tot o ebb e dnoyebb eyond 1L!+OO 400 .sdnuorr ounds. IIt t iis s thguohtt hought tatht hat
etht he gnitatror otating dnabb and oof f etht he elitcejporp rojectile dluoww ould ebb e depspirts tripped erofebb efore ehtt he -erpp re
ddetcid icted ycaruacca ccuracy llife ife dluoww ould ebb e dehcaerr eached ,adna nd, ,eroferteht herefore, tatht hat ehtt he sgnippirts tripping ,
oof f etht he gnitatror otating dnabb and dluoww ould enidmreted etermine ehtt he laautca ctual llife ife oof f ehtt he .ngug un.
ytiroAhtuA uthority f rof or T :tseT est: 0 00 0 605/19.4174 71.91/506 YTPREPORP ROPERTY n FD F U .S.U .S. A Y'NA RYl
S OFNITS TINFO BBRAWH RANCR
A GPA PG 231/51.4274 72.15/132
1 .%3 3RL. A ,GPA PG, ,,m. MD. .120012 100S
"
O TCEJBO BJECT O FO F T TSET EST
T ehT he otcejbo bject o fo f t eht he t tset est i si s t ot o g teg e eht t the e tceffe ffect o fo f t eht he
f gnirif iring o no n t eht he gnifnoitcnuf unctioning o fo f t eht he mlairetam aterial a dna nd t ot o p tciderp redict
E a ta t w tahw hat ptniop oint i ni n t eht he l efil ife o fo f t eht he g nug un i ti t w lli~: ill b eb e m tsom ost a -da d
v suoegatnav antageous t ot o wwardhtiw ithdraw t eht he g nug un f morf rom sservice. ervice.
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D NOITPIRCSED ESCRIPTION O FO F M LAIRETAM ATERIAL
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:a
hcnI-xiS nuG ,0091M .oN ,64 htiw a "7.4 reniL 2T no a
Six-Inch Gun M1900, No. 46, with a 4.7" Liner T2 on a
6 "6 " leehW M tnuoM ount 1 .7191 917. T ehT he l renil iner i si s s ytxis ixty c srebilac alibers i ni n l htgnel ength
~lheel
gnidulcni( )rebmahc dna sah owt-ytrof sdnal dna sevoorg vJith
(including chamber) and has forty-two lands and grooves with
a a t tsiwt wist o fo f o eno ne t nrut urn i ni n t evif-ytnewt wenty-five c .srebilac alibers. T sihT his g nug dahun had
ii n ton ot b neeb een p ylsuoiverp reviously f .derif ired. ._ , /- .--
noitinummA :stnenonmoC
Ammunition Components:
P elitcejorP rojectile - 4 "7.4 .7" A .A.A .A. S llehS hell T .5T 5. "
C esaC ase - 4 "7.4 .7" T lT l f rof or 4 "7.4 .7" T 2T 2 G .nuG un.
F ezuF uze - 3 03 0 S sdnoceS econds M lacinahceM echanical T emiT ime F ezuF uze T .2E13T 3lE2.
P redwoP owder - - D sttnopuD upont's N HN H S sselekomS mokeless P ,redwoP owder, L toL ot X S-4863-X -3684-S
fo 1391 rof 116 nuG .80-lM-7981M tI saw
of 1931 for 6" Gun M1897-MI-08. It Vlas
u desu sed b htob oth l esool oose a dna nd b.deggab agged. " nehW lhen bdeggab agged
t eht he c egrahc harge w saw as a delbmessa ssembled i ifi n a a s klis ilk b gab ag
w htiw ith a a l decal aced c egrahc harge o fo f 8 8 o .zo z. o fo f b kcalb lack
p.redwop owder. T ehT he retingi w saw as p decalp laced i ni n t eht he
ignit~r
esab fo eht egdirtrac ;esac neht eht gab
base of the cartridge case; then the bag
o fo f repdwop owder ptup ut i otni nto t eht he c esac ase a dna nd detlojjolted
,nwod dna eht esac desolc htiw a kroc
down, and the case closed with a cork
gulpp lug T.lT I. eThT he egrcahc harge ,desuu sed, 282 8 l .sbl bs. 8 8 ,o.zo z.,
si tuoba eht mumixam taht nac eb delbmessa
is about the maximum that can be assembled
ni eht .esac
in the case.
remirP - 003 .rG lA82M desu htiw redwop dedaol ni
Primer - 300 Gr. M28Al used with powder loaded in
esoolloose .egrahccharge.
0220 .rGGr. lA32MM23AI desuused htiwwith redwoppowder dedaolloaded niin gabbag
< .segrahc
charges.
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.* ATAD .'
ruoF derdnuh dna eerht-ytxis sdnuor erew derif morf eht
Four hundred and sixty-three rounds were fired from the
gun.
,yticoleVVelOCity, ,erusserppressure, dnaand htgnellength foof liocerrecoil erewwere nekattaken noon
lla .sdnuor A rebmun fo sdnuor erew derif rof yrevocer dna
all rounds. A number of rounds were fired for recovery and
ehtthe sllehsshells .denimaxeexamined. egdirtraCCartridge sesaccases ereFwere denimaxeexamined roffor
gnitulf dna .noitarutbo
fluting and obturation. -
ratS eguaG sgnidaer dna ecnavda fo gnicrof enoc dna
star Gauge readings and advance of forcing cone and
gnitaes erew nekat gnirud eht esruoc fo .gnirif
seating were taken during the course of firing.
E
segnaR erew devresbo fo esoht sdnuor derif rof yrevocer
Ranges were observed of those rounds fired for recovery
tub erew ton desu ni siht .troper
. but were not used in this report.
-2-
-2-
Over Over owttwo derdnuhhundred sdnuorrounds erewwere deriffired otto tegget semittimes foof ,thgilfflight,
tsommost foof hcihwwhich erewwere htiwwith aa five five dnocessecond ezuffuze .gnittessetting.
ehTThe tsallast ruof-ytrihtthirty-four sdnuorrounds erewwere deriffired htiwwith ehtthe pillip foof
gnitatorrotating dnabband tuccut .ffooff.
sdnuoRRounds 231132 otto l/l141 erewwere deriffired otto tegg ehtet the ytilibatsstability rotcaffactor
foof ehtthe .llehsshell. i .P" ,-
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GNINOITCNUFFUNCTIONING FOOF LAIRETAMMATERIAL ' 1 ,'
d
.II. nuGGun dnaand :epairraCCarriage:
ehTThe nugg dnaun and egairraccarriage denoitcnuffunctioned ylirotcafsitassatisfactorily ,dnaand,
onno ytluciffiddifficulty sawwas decneirepxeexperienced niin .gniriffiring. ,revewoHHowever, ehtthe tnuommount
sawwas very very elbatsnuunstable yllaicepseespecially taat wollow .snoitaveleelevations.
nIIn llaall ehtthe sdnuorrounds ehtthe nuggun deriffired htinwith aa egrallarge wolleyyellow
hsalff lash dnaa and a llasms mall tnuomaamount foof elzzummuzzle .ekomss moke.
.IIII. gnilleporPPropelling :egrahCCharge:
tAAt ehtthe gninnigebbeginning foof ehtthe gnfriff iring ehtthe redwoppowder sawwas dekcappacked
eslool oose ini n etht he c .esac ase. AtA t dnuRoR ound 464 6 htwiw ith a a tnalleporpo ropellant egrahccharge foof
232 3 I.sbl bs. g 8 ,o.zo z., etht he egaareva verage elzzmum uzzle yticvolev elOCity w saw as 19303 091 fs/f /s dnaand
elbaborpp robable erorre rror i ni n elzzmum uzzle yticvolev elocity swaw as 1 61 6 f .s/f /s. eThT he noisrepsiddispersion
htwiw ith a a eslool oose egcrahc harge gniebb eing s os o g ,taerg reat, a a egncahc hange a ta t ehtthe noitsegguss uggestion
o fo f M .rM r. saw,namleAdA delman, was edmam ade tot o deggabb agged c segrahc harges hciwhw hich tuccut nwoddown ehtthe
nodisrepsid ispersion ylbarecdisnoc onsiderably t ot o ,L 4 f .s/f /s. I nI n vview iew o fo f t siht his noitcudrer eduction
i ni n ,nodisrepsid ispersion, a tsomla lmost a lla ll tnesuqesbus ubsequent f sgnirif irings w erew ere edmam ade htwis ith
t eht he degbgab agged c .segrahc harges.
O fO f,t eht he 4 364 63 srdnuor ounds f ,derif ired, t eht he v yticolev elocity dana nd erusseprp ressure
d atad ata o fo f 1 191 91 r sdnuor ounds w erew ere u desu sed i ni n ggnitteg etting t eht he ccurves urves o fo f t siht his
r .troper eport. T eseffT trese 1 191 91 r sdnuor ounds w erew ere f derif ired w htiw ith dbeggab a.gged c segrahc harges a dna nd
e snoitavele levations o fo f 4 f51O4 °15' oor r l .ssel ess. T ehT he l wol ow e snoitavele levations a wolla llow t eht he
u esu se o fo f l gnol ong s neercs creen d ecnatsid istance a dna nd eht v yticolev elocity d atad ata denoiatbo btained
t~e
w htiw ith t eht he grnitluser esulting l regnol onger t emit ime i slavretni ntervals a era re c deredisnoc onsidered m erom ore
r elbailer eliable t naht h atad an data o deniatbo btained w htiw ith h hgih igh a elgna ngle f .erif ire.
T ehT he i laitini nitial v yticolev elocity o fo f t siht his T 2T 2 G nuG un w htiw ith a a p -orp ro
p tnallep ellant c egrahc harge o fo f 2 32 3 l .sbl bs. 8 8 o .zo z. w saw as 3 5213 125 f s/f ls a sa s c derapmoc ompared w htiw ith IlJ' ;
t eht he 3 4223 224 f s/f ls w htim ith a a tnpalleporp ropellant c egrahc harge o fo f 2 7.42 4.7 I .sbl bs. t taht hat w saw as
r dednemmocer ecommended f rof or a a 4 "7.4 .7" A .A.A .A. G nuG un i ni n B citsillaB allistic R hcraeseR esearch L -arobaL abora
t yrot ory R tropeR eport N .oN o. 1 ,521 25, " A" A C nosirapmoC omparison o fo f A tfarcriaitnA ntiaircraft G snuG uns o fo f
V suoiraV arious C .nsrebilaC alibers". -
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erugiF 1 swohs tahw saw gnineppah gnirud eht esruoc
Figure 1 shows what was happening during the course
fo .gnirif tI sniatnoc shparg fo ,yticolev ,erussero yticolev
\, - of firing. It contains graphs of velocity, pressure, velocity
noisrepsid , erusserp ,noisrepsid ecnavda fo gnicrof ,enoc -da
dispersion, pressure dispersion, advance of forcing cone, ad
vance fo gnitaes dna noisore dettolp tsniaga eht rebmun fo
vance of seating and erosion plotted against the number of
sdnuor derif morf eht .nug ehT shparg fo ,yticolev ,erusserp
rounds fired from the gun. The graphs of velocity, pressure,
yticolev ,noisrepsid dna erusserp noisrepsid versus sdnuor
velocity dispersion, and pressure dispersion versus rounds
derif erew edam morf a lacitsitats tniopweiv ot wohs eht -ed
fired were made from a statistical viewpoint to show the de
eerg fo *lortnoc htiw hcihw eht atad saw .nekat
gree of control* with which the data was taken •
..
erugiF 2 dna erugiF 3 wohs curves fo egareva elzzum
Figure 2 and Figure 3 show curves of average muzzle
yticolev dna noisrepsid fo elzzum ,yticolev ,ylevitcepser
velocity and dispersion of muzzle velocity, respectively,
dettolp tsniaga rebmun fo sdnuor derif ni eht lanoitnevnoc
plotted against number of roupds fired in the conventional
.rennam f\
manner.
\r
s ratS t-ar egGuaG auge ccurves urves aera re .dehcaatta ttached. 0
.IIII II. egdirCtraC artridge C :esaC ase:
nI eht ytirojam fo sesac ,desu gnitulf saw deton no
In the majority of cases used, fluting was noted on
eht kcen fo eht esac deinapmocca yb llams stnuoma fo demusnocnu
the neck of the case accompanied by small amounts of unconsumed
.kroc nI eht ,niam gnitulf saw ylno thgils hguohtla ti deirav
cork. In the main, fluting was only slight although it varied
morf thgils ot peed dna yllausu eht tnuoma fo demusnocnu kroc
from slight to deep and usually the amount of unconsumed cork
deirav .ylgnidrocca
varied accordingly.
tuohguorhT eht gnirif eht lT egdirtraC esaC dewohs
Throughout the firing the Tl Cartridge Case showed
roop .noitarutbo
poor obturation.
GPA .otohP 44654:oN swohs gnitulf ni egdirtrac
APG Photo. No. 45644 shows fluting in cartridge
sesac retfa .gnirif
cases after firing.
tI si thguoht taht eseht stcefed ni eht egdirtrac
It is thought that these defects in the cartridge
- sesac era desuac yb oot hcum ecnaraelc neewteb eht kcen fo
cases are caused by too much clearance between the neck of
esac dna nug dna taht ti dluoc eb detcerroc yb gnisaerced
case and gun and that it could be corrected by qecreasing
eht tnuoma fo eht .ecnaraelc
the amount of the clearance.
.VI Qo?P :elitce
IV. P+ojectile:
A .A . ydBoB ody o fo f lSlehS hell
gnivargnE saw deton woleb gnitator dnab over
Engraving was noted below rotating band over
trap fo eht '.ecnerefmucric nI eht ylrae segats fo ,gnirif
part of the circumference. In the early stages of firing,
etht he gniveargne ngraving w saw as peded hguoneeep enough tot o tnarrwaw arrant .noitagitsevnii nvestigation. .feR(( Ref.
A GPA PG .otoPhP hoto. .oNNo. .)34.475~ 5743). lenoCloC olonel ginrZoZ ornig dnuoff ound tii t tc to ebbe desuaccaused
yb cirtnecce .gnidaol nopU erom luferac gnidaol htiw muirab
by eccentric loading. Upon more careful loading with barium
etahplus daetsni fo der dael dna eniffarap GPA( .otohP
sulphate instead of red lead and paraffine (APG Photo.
.oN 8136.4 dna .oN ,)9136& eht gnivargne saw ylbaredisnoc -er
No. 46318 and No. 46319), the engraving was considerably re
decud GPA( .otohP .oN .)68661
duced (APG Photo. No. 46686).
*
* SSimon, imon, L .L . EE. . " nA" An slreenEignE ngineer's lauMnaM anual oof'Statistica1 f Statistical ,&sdohteMMethodsJ,
nhJoJ ohn WWiley iley dana nd S ,snoS ons, 1 .l491 941. .
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thgilS gnivargne no telerruob saw deton no
Slight engraving on bourrelet was noted on
. . suoirav sllehs over trap ro etelpmoc .ecnerefmucric
various shells over part or complete cir 7 cumference.
,
nI emos ,sesac eht retemaid fo eht llehs retfa
In some cases, the diameter of the shell after
gnieb derevocer saw sa hcum sa ~~lO. retaerg naht erofeb .gnirif
being recovered was as much as .01" greater than before firing.
3 H ,revewoH owever, t ereht here i si s tineiciffusni nsufficient e ecnedive vidence t ot o d ward raw a yna ny ncoisulcnoc onclusion
sa ot eht esuac fo siht .gnittespu
as to the cause of this upsetting.
'0,, .--
.-
. B .B . gRnitatoR otating B dnaB and
.- / :
llA sllehs derif rof yrevocer deraeppa ot eb
All shells fir-ed for recovery appeared to be
ylirotcafsitas devargne ot evig lluf .nips ,revewoH etaredom
satisfactorily engraved to give full spin. However, moderate
dna thgils gniraehs fo gnitator sdnab saw .deton A rojam
and slight shearing of rotating bands was noted. A major
trap fo eht gniraehs si osla deredisnoc ot eb na tceffe fo
part of the shearing is also considered to be an effect of
e cirtnecce ccentric .lgnidaol oading. F erugiF igure 4 *4 * i si s a a d margaid iagram gniitartsulli llustrating h woh ow
ti si thguoht taht eht lagufirtnec ecrof no a llehs esohw
it is thought that the centrifugal force on a shell whose
c retnec enter o fo f g ytivarg ravity i si s o ffo ff t eht he aaxis xis o fo f t eht he s llehs hell d eud ue tot o
cirtnecce gnidaol sesuac eht gnilfir ot "etib" otni eht
eccentric loading causes the rifling to "bite" into the
gnitator dnab no eno edis dna ylno yllaitrap evargne eht
rotating band on one side and only partially engrave the
rehto .edis
other side.
.otAohP GPA PG Photo. N .oN o. 847464 6478 s swohs hows i secnatsni nstances o fo f dogog ood
e gnivargne ngraving t ot o emtaredom oderate sgniraehs hearing oof f r gnitator otating .bdnab and. AGPA PG .otPohP hoto.
N .oN o. 874764 6778 s swohs hows t eht he noictidnoc ondition o fo f gnitrator otating dbnab and a retfa fter 0424 20
sdnuor erew .derif
rounds were fired.
oNN o s gnippirts tripping oof f etht he gnitrator otating dnabb and sawwas -boob
sserved. erved. erTehT here w saw as aosla lso onn o .gnignfirf ringing.
erugiF 5 si a tolp fo elzzum yticolev versus
Figure 5 is a plot of muzzl~ velocity versus
,gnitaes rof gnirif taht saw enod htiw eht pil cf eht gnitator
seating, for firing that was done with the lip of the rotating
dnab tuc ffo dna eht elitcejorp detaes yb gnimmar htiw thgie
band cut off and the projectile seated by ramming with eight
.nmem en. sdn(uoR( Rounds .)364-9434 39-463). TehT he p tolp lot isetacidni ndicates a a ecnednepded ependence oof f --
noisrepsid fo elzzum yticolev nopu ,gnitaes ,.e.i eht elzzum
dispersion of muzzle velocity upon seating, i.e., the muzzle
seitvicolev elocities f rof or etht he selitcejorpp rojectiles hcihww hich ereww ere destaes eated drahhard puup in in
eht nug dah hcum ssel noisrepsid naht eht elzzum seiticolev
the gun had much less dispersion than the muzzle velocities
roff or selitcejorpprojectiles hcihwwhich erewwere detaess eated sselless ffirmly.= irmly.**
ehT elbaborp rorre fo eht elzzum yticolev rof
The probable error of the muzzle velocity for
ehtthe selitcejorpprojectiles htiwwith sgnitases eatings foof '79449" otto "8/j-9/49-3/8" sawwas detaluclaccalculated
ot eb 6 .s/f gnirapmoC eht 6 s/f elbaborp rorre ta 054 sdnuor
to be 6 f/s. Comparing the 6 f/s probable error at 450 rounds
htiw pil fo gnitator dnab tuc ffo htiw eht 71 s/f elbaborp
with lip of rotating band cut off with the 17 f/s probable
rorre ni yticolev ta 004 sdnuor htiw pil ,no ti si thguoht
error in velocity at 400 rounds vdth lip on, it is thought
tahtthat ehtthe major major trappart oof f ehtthe esaercniincrease in in noisrepsiddispersion of of elzzummuzzle
yticolevvelocity erugiF(( Figure )33) naccan ebbe detubirttaa ttributed otto ehtthe "fiartificial~~ artificial"
gnitaesseating desuaccaused ybby ehtthe .pillip.
E -.
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detsegguSSuggested ybby fi=fmes igures deraperpprepared ybby lenoloCColonel .ginroZZornig.
**** ehTThe ytilibaborpprobability tahtthat ehtthe velocitives elocities deniatboobtained htiwwith sgnitaesseatings retaerggreater nahtthan "2/l-#48-1/2"
degnolebbelonged otto aa universe universe different different fromf rom tahtthat of of ehtthe velocitives elocities deniatboobtained htiwwith :
sgnitaesseatings sselless nahtthan 112/l-3@48-1/2" sawwas detaluclaccalculated otto e3be retaerggreater nahtthan "999.00.999" gnisuusing
s'rehsiFFisher's Xg -- tsettest saas given given noon segappages 444-434434-444 in in eluYYule dnaand ,s'lladneKKendall's, nA“"An -ortnIIntro
noitcudduction otto ehtthe yroehTTheory of of 3tatisticsS". tatistics".
-5--5-
cc. . B esaB ase C ,revoC over .
........ .
O nO n a lla ll s sllehs hells f ,derif ired, t eht he b esab ase ccovers overs r deniamer emained
i tcatnI ntact a dna nd s .thgiarts traight.
; D wD . .. ' ytilibatSStabili ty
T ehT he s ytilibats tability o fo f t eht he s llehs hell w saw as idetagitsevni nvestigated
. b yb y H .H . P .P . H kcochctiH 1tchcock i ni n B citsillaB allistic R hcraeseR esearch yroLtarobaL aboratory R tropeR eport
N .oN o. 2 ,732 37, y"t.ilibatSn stability o fo f 4 "7.4 .7" S llehS hell T ."5T 5". T ehT he s ytilibats tability f rotcaf actor
a ta t a a melzzum uzzle v yticolev elocity o fo f 3 0403 040 s/ffls w saw as f dnuof ound t ot o b eb e 2 48.2 .8L a dna nd
i ti t w saw as derdnemmocer ecommended t taht hat t eht he t tsiwt wist o fo f rgnilfir ifling b eb e cdegnahc hanged f morf rom
1 52/l /25 t ot o 1 43/l /34 ( gnikam( making t eht he s ytilibats tability f rotcaf actor 1 )05.1 .50) etsaercni-ot o ,increase .I
t eht he l efil ife o fo f t eht he g .nug un.
E .E . F mroF orm F rotcaF actor
T ehT he f mrof orm f rotcaf actor w saw as dfnuof ound t ot o b eb e 0 09.0 .90 w hcihw hich
i si s t eht he s emas ame a sa s ttaht hat u desu sed f rof or t eht he 4n7.4 .7" A .A.A .A. G nuG un i ni n cBitsillaB allistic
R hcraeseR esearch yrotarLobaL aboratory tRropeR eport N .oN o. 1 ,521 25, " A" A noCsirapmoC omparison o fo f A-itnA nti
a tfarcria ircraft G snuG uns o fo f sVuoiraV arious .ns.CrebilaC alibers".
Vv. . O rehtO ther :stnCenopmoC omponents:
A .A . P remirP rimer
htBoB oth ehtt he lA8M2M 28Al remirpp rimer d(esu( used htwiw ith ehtt he eslool oose
)secgrahc harges) dana nd ehtt he lA3M2M 23Al remirpp rimer d(esu( used htwiw ith ehtt he deggabb agged )secgrahc harges)
deraepapa ppeared tot o g evig ive yrotcsafsitas atisfactory .noitinigi gnition. gninesoLoL oosening o fo f ehtt he
remirpp rimer ini n ehtt he c esac ase o ro r gnidnebb ending ini n ehtt he remirpp rimer ydobb ody w saw as tonn ot
.detonn oted.
B .B . ezuFF uze
O tuO ut o fo f ehtt he l2/2 41 sdnuror ounds defrif ired tot o tgeg et emtit ime o fo f
,thgilf ereht erew eerht seruliaf ot noitcnuf dna eno -erp
flight, there were three failures to function and one pre
.erutammature.
ezuFFuze gnittSeS etting .oNNo. foof sdnuoRRounds . .oNNo. foof seruliaFFailures
55 1081 80 0o
10 41 1
::30 02- 1420 ' 2 12
ehTThe erutamerppremature taa t .dRRd. 924429 derruccooccurred htiwwith ehtthe pillip foof ehtthe gnitatorrotating
dnabband tuccut ,ffooff, aa relliffiller foof muirabbarium ,etahplussulphate, ,eniffarapparaffine, dnaa and a
211 2 .zooz. egrahccharge foof kcalbblack redwoppowder roffor ,gnittopsspotting, dnaand ehtthe llehsshell
demmarrammed htiwwith esaccase hcihwwhich diddid tonnot ,taesseat ehtthe elitcejorpprojectile noon ehtthe
gnicrofforcing .enoccone.
ehT elbaborp rorre fo emit fo ta,thgilf
The probable error of time of flight at
03 sdnoces ezuf gnittes saw 32. .sdnoces
30 seconds fuze setting was .23 seconds.
6-
-6-
I
, I
. 1
i , J ! :\‘
I; , (‘):, I . ,\, \: !: . ,, / \\\ \ ;. ., -‘ __-
I ,I! !,
’. i I . I
!.’ _
. .
\‘\
\\ \ <- ’:
I , I I : 8 ' ’ \‘\ i : .\i . \\I , \ ' '. , .K.~ ,,K“ YCARUCACA - ..--C-....C , URACY EFILL IFE s -< ~-. -:- .e . _' ..'' rIi i -_ ',
1 \ ,
nI siht troper eht ycaruka efil fo a nug si denifed
\ In this report the accuracy life of a gun is defined
a sk s ehtt he rebmnun umber - fo of sdnuror ounds defrif ired f morf rom ehtt he ngug un f rof or hciwhw hich ehtt he
egaareva verage c tsoc ost reup er ++thih it* i si s a a .mumimnim inimum. egarAevA verage c tsoc ost repp er tihh it
: 2
s$ ehtt he c tsoc ost o fo f ehtt he etelcpmoc omplete sdnuror ounds o fo f noitinuamma mmunition sulpp lus a a
~s
wenn ew ebutt ube degaareva veraged f morf rom f tsrif irst dnuorr ound tot o l tsal ast dnuorr ound .derediscnoc onsidered.
*
rOehtO ther aircetirc riteria ymam ay ebb e s tes et puu p f rof or ehtt he ycaarucca ccuracy elfil ife o fo f
ehtt he ,ngug un, s hcus u sa ch as ehtt he tniopp oint erehww here ehtt he gnitatorr otating dnabb and i si s dersaehs heared
o ro r ,depspirts tripped, o ro r erewhw here ehtt he elzzumm uzzle yticvolev elocity shah as deppodrd ropped tot o s hcus uch
. a a evulav alue tatht hat ehtt he ngug un toncnac annot hsilapmocca ccomplish i sti ts .esoprupp urpose. ,tBuB ut,
,yllatnemadfnuf undamentally, yehtt hey aera re alla ll ono nan an cimeonoce conomic .sisabb asis. rFoF or ,elpemaxe xample,
ehtt he gnippsirts tripping o fo f gnitatorr otating ,dnabb and, hciwhw hich ymam ay tonn ot o rucco ccur erofebb efore
ycaarucca ccuracy elfil ife a sa s a evoba bove denifded efined i si s ,dehcaerr eached, thgmim ight ebb e desuu sed tot o
enimredted etermine ehtt he ycaarucca ccuracy ;elfil ife; o ro r ehtt he gnippsirts tripping ymam ay c emoc ome reatfa fter
ehtt he ycaarucca ccuracy elfil ife i si s ,dehcarer eached, ini n hciwhw hich c esac ase i ti t i si s tonn ot ylono nly
elbatiforpnuu nprofit.able tot o ferif ire ehtt he ngug un tubb ut aosla lso vvery ery yldedidced ecidedly -icarpmi mprac
elbactit icable tot o dod o s .os o.
AAs s ehtt he ngug un i si s ,def.rif ired, ehtt he egaareva verage elzzumm uzzle yticvolev elocity d-ed e
c sesaerc reases dana nd ehtt he noisredpsid ispersion o fo f elzzumm uzzle yticvolev elocity .sesaiercni ncreases.
esehT srotcaf tceffa eht ycarucca efil fo eht nug ni os
These factors affect the accuracy life of the gun in so
raf sa yeht tceffa eht rebmun fo sdnuor yrassecen ot erocs
far as they affect the number of rounds necessary to score
a tih lacorpicer( fo ytilibaborp fo a .)tih
a hit (reciprocal of probability of a hit).
nI eht gniwollof snoitaluclac ot tciderp ycarucca ,efil
In the following calculations to predict accuracy life,
ti si ylticilpmi demussa taht eht gnitator sdnab era -sitas
it is assumed that the rotating bands are satis-
im~licitly
yliroftcaf actorily devaergne ngraved tot o g evig ive lfluf ull s nips pin ott o ehtt he .selitcejorpp rojectiles.
r
ItI t i si s aosla lso tnatroipmi mportant tot o etonn ote tahtt hat m tsom ost o fo f ehtt he atdad ata erwew ere o-bo b-
deniatt ained ybb y gnitaloparetxe xtrapolating f morf rom ehtt he detilmil imited atdad ata elbalaiava vailable f morf rom
ehtt he .gnfirif iring.
11
ehT lacitcat noitautis detaert si taht fo eht nug gnirif
The tactical situation treated is that of the gun firing
ta na enalpria gniylf level ta 003 selim rep ruoh ta na -itla
at an airplane flying level at 300 miles per hour at an alti
edut fo 000,01 sdray dna a tnals egnar fo tuoba 000,51 .sdray
tude of 10,000 yards and a slant range of about 15,000 yards.
tceffE fo esaerceD ni egarevA elzzuN :yticoleV
Effect of Decrease in Average Muzzle Velocity:
erugiF 2 gives eht curve fo eht noitaler fo egareva
Figure 2 gives the curve of the relation of average
elzzum yticolev ot eht rebmun fo sdnuor derif morf eht nug
muzzle velocity to the number of rounds fired from the gun
dana nd ybb y ,noitaloparetxe xtrapolation, ana n etameitse stimate o fo f ehtt he egaareva verage elzzumm uzzle
seiticolev dnoyeb ruof derdnuh sdnuor saw .deniatbo
velocities beyond four hundred rounds was obtained.
' ** This noitinifed si eellac cimonoce efil yb niatpaC rehyeW in sih
This definition is calle~ economic life by Captain Weyber in his
,troprer eport, " tsriF" First tropReR eport ono n gnirFiF iring T stseT ests t ot o enimretDeD etermine stLimiL imits ofo f ycaruAccA ccuracy efLiL ife
o fo f 1 M.M551 55MM ,GnuG un, ".FG.P.G .P.F." - - O.0 . P .P . .oNN o. '25145 412'
-,
- -7- 7-
,,'
IV
,.I ..... \
. :
\
•
AAs s etht he egaareva verage elzzmum uzzle yticvolev .e:. locity ,sesaderced ecreases, etht he emittime foof
thgfilf light o fo f etht he elitcejorpp rojectile .sesaiercni ncreases. eThT he ytilibaborpp robability foof
gnitthih itting vvaries aries yleisrevni nversely a sa s etht he ersauqs quare o fo f etht he etmit ime foof
*.thfgilf light.*
eThT he etmit ime o fo f sthfgilf lights erwew ere deniatobo btained f morf rom a a detalucclac alculated
ccurve urve o fo f etmit ime o fo f thgfilf light vversus ersus elzzmum uzzle yticvolev elocity a ta t aa "5445°
stnals lant egnarr ange o fo f 6146,51 5,646 .sdryay ards. eThT he rebmnun umber o fo f sdnuror ounds -noccon
dersedis idered erwew ere detilmil imited tot o 1 00.U 400 sdnuror ounds s ecnis ince rehftruf urther gniriff iring
dluwow ould etatissecnen ecessitate a a etmit ime o fo f thgfilf light retagerg reater natht han 0330 ,sdnocses econds,
hciwhw hich i si s etht he m mumixam aximum efzuf uze .gnsittes etting.
.P
gniredisCnoC onsidering etht he rebmnun umber o fo f sdnuror ounds repp er thih it a sa s ytinuunity nehwwhen _
etht he ngug un i si s ,wnen ew, etht he evitarler elative rebmnun umber o fo f sdnuror ounds repp er tihhit taa t
v suoirav arious s segats tages ini n etht he elfil ife o fo f etht he ngug un w saw as detalucclac alculated dnaand
etht he stlurser esults aera re snwohs hown yllacihpgarg raphically i ni n erugFiF igure 6 .6 .
tcEeffE ffect o fo f esaerIcnI ncrease ini n noisreuDsiD isuersion o fo f elzzMuM uzzle :yticolVeV elocity: ’
erug'iF‘ Figure 3 3 s swohs hows etht he ccurve urve o fo f pihsnoitalrer elationship o fo f elbaborpprobable
erorre rror ini n elzzmum uzzle yticvolev elocity tot o rebmnun umber o fo f sdnuror ounds dferif ired morffrom ehtthe
ngug dnaun and ybb y ,noitaloparetxe xtrapolation, ana n etaemitse stimate o fo f etht he elbaborpp robable rorree rror
dnoyebb eyond etht he rfuof our derdnuhh undred sdnuror ounds aera re .deniaotbo btained.
eThT he melborpp roblem i si s S ralimis imilar tot o taht fothat of ,gnibmobb ombing, detaerttreated niin
citsiBllaB allistic hcraReseR esearch yrotarobLaL aboratory tropReR eport NMO. o. ,l2/2 41, m"umitpOft Optimum 1
gnSicapS pacing o fo f BsbmoB ombs o ro r S stohS hots ini n etht he ecnesPerP resence o fo f ciStametsyS ystematic
"EsrorrE rrors" ybb y L.L . S .S . ,kcireDdeD ederick, R .R .H. H. ,tnKeK ent, dana nd A.A . O .0 . ,htiSmS mith,
htwiw ith ana n xidneappa ppendix ybb y JJ. . vvon on .nnamueNN eumann. erTehT here i si s ana n yltcefrepmiimperfectly
detalcol ocated tegrtat arget edud ue tot o erorre rror ini n etht he ferif ire lorctnoc ontrol ,stnemurtsniinstruments, ,‘
scitametsys ystematic ,erorre rror, dana nd eretht here i si s a a noisredpsid ispersion o fo f etht he stsrubbursts
o fo f etht he s sllehs hells tuaoba bout etht he gniamia iming ,tnio’pp oint, latnedaicca ccidental ,rorree rror, euddue
tot o noisredpsid ispersion o fo f yticvolev elocity dana nd etmit ime tot o tsrbub urst o fo f .efzuf uze. ehTThe
lapicnirpp rincipal e srorre rrors i ni n alla ll o fo f etht he a evoba bove eertht hree - -- - noitalcol ocation foof
,tegrtat arget, elzzmum uzzle yticvolev elocity dana nd gnimtit iming o fo f efzuf uze - -- - leil ie gnolaalong
etht he stnals lant egnarr ange ,adna nd, ,eroferetht herefore, etht he melborpp roblem i si s deifislpmis implified
f morf rom etht he eertht hree snoisndemid imensions o fo f s ecaps pace tot o etht he eono ne noisnedmid imension
gnoala long etht he s tnals lant .egnrar ange. -
eThT he noitaeuqe quation f rof or etht he ytilibaborpp robability o fo f gnitthih itting
r
n ' tn- nl wWr
p P = = I l(-y1-( _l)r-l
1 1 - r-l
\j
trI)(r-n( n-r)lrt 2w( 2 ++ )etE ~+I!= )2 w2 + e2 + r e2
(\V ex s
*
R .R .H. H. ,KtneK ent, BBallistic allistic hcraesReR esearch yrotarobLaL aboratory tropReR eport .oNN o. 1 ,721 27, ehT"" The
P ytilibaborP robability oof f HHitting itting ana n enalpAriA irplane a s,a s tnednepDeD ependent nopuu pon sroErrE rrors in in ehtthe
thgHieH eight reFdniF inder dana nd etht he D .'lrotceriD irector". '
: R .R .H. H. ,KtneK ent, BBallistic allistic hcraesReR esearch yrotarobLaL aboratory tropReR eport .oNN o. 1 ,231 32, ehT"" The
P ytilibaborP robability oof f HHitting itting suoiVraV arious sPtraP arts oof f ana n enalpAriA irplane a sa s tnednepeDDependent noon
etht he noitatnemFgarF ragmentation scitsirCetcarahC haracteristics oof f a a PProjectilef'. rojectile".
-8-
-8-
------------- _-. - - . - _- - -- - . _ ”._ ._ .-_. “.
n == rebmun fo stohs derif
· n number of shots fired
.I .
b2W == htdiw fo, tegrat
"'2w width-of t .‘arget
12
£Ecc cx == v-, 2 tsemit imes dradsnats tandard noitadived eviation o fo f latnediccaaccidental rorree rror
V
I 3 £ se s == 2 tsemit imes dradsnats tandard noitadived eviation o fo f cit&metssys ystematic rorree rror
--Yv-
, si devired ni eht xidneppA desab yltcerid no eht xidneppa ot
1s derived in the Appendix based directly on the appendix to
citsillaB hcraeseR yrotarobaL tropeR .oN 142 yb J. von .nnamueN
Ballistic Research Laboratory Report No. 241 by J. von Neumann.
tI yam eb nwohs morf siht noitauqe taht ereht si na mumitpo
It may be from this equation that there is an optimum
sho\~
noisrepsid fo eht stsrub dnuora eht gnimia .tniop
dispersion of the bursts around the aiming pOint.
. .
ehT elbaborp rorre fo emit fo ezuf ta eht gnittes fo .03
The probable error of time of fuze at the setting of 30
s,sdnoces econds, . 32. 23 ,sdnoces econd, c sesuac auses a a elbaborpp robable nireorre rror in s tnals lant egnarrange
fo ythgie .sdray ehT rorre ni tnals egnar eud ot noisrepsid
of eighty yards. The error in slant range due to disgersion
ni elzzum yticolev saw deniatbo morf a detaluclac hparg fo
in velocity was obtained from a calculated graph of
~uzzle
tnals egn.ar versus elzzum .yticolev ehT latnedicca rorre si
sl2nt range versus muzzle velocity. The accidental error is
thevsum fo eht serauqs fo eht evoba owt .srorre
the~sum of the squares of the above two errors.
eThT he elbaborpp robable erorre rror gnoala long stnals lant ezr.rar aLle ini n gnitalcol ocating ehtthe -rattar
teg (rs) saw nekat ot eb 058 sdray htC eht esu fo tneserp
get (rs) was taken to be 850 yards with the use of present
thgiehh eight srefdnif inders. . ( eeS( See citsilBlaB allistic hcraReseR esearch yrotarobLaL aboratory tropeRReport
.oNN o. 1 ,721 27, eh"TfI The ytilibaboPrP robability o fo f gnittHiH itting ana n enalprAiA irplane saas tnednepeDDe;)endent
nopu srorrE ni eht thgieH redniF dna eht ,”rotceriD egap .)8
upon Errors in the Height Finder and the Director", page 8).
eThT he rebmnun umber o fo f s stohs hots etht he ngug un dferif ired a ta t a a enalpp lane gnimoccoming niin
ot bmob saw demussa ot eb seven dna eht htdiw fo eht tegrat
to bomb was assumed to be seven and the width of the target
demussa ot eb ytfif .sdray
assumed to be fifty yards.
erugiF ,7 evitaleR rebmuN fo sdnuoR re3 tiH susreV rebmuN
7, Relative Number of Rounds Per Hit Versus Number
Figur~
fo sdnuoR deriF morf eht ,nuG saw detaluclac gnisu eht evoba
of Rounds Fired from the Gun, was calculated using the above
.noitauqe
. equation.
ehT wen oidar rotacol lliw ecuder eht citametsys ,rorre
The new radio locator will reduce the systematic error,
dna os eht snoitaluclac erew osla deirrac tuo gnimussa a
and so the calculations were also carried out assuming a
elbaborp rorre ni gnitacol eht tegrat gnola tnals egnar fo
probable error in locating the target along slant range of
052 sdray dna eht stluser era nwohs ni erugiF .8
250 yards and the results are shovm in Figure 8.
erugiF 7 swohs taht htiw eht tneserp ,srotcerid eht -sid
Figure 7 shows that with the present directors, the dis
noisrep fo eht stsrub fo eht sllehs dah ton dehcaer sti -itpo
persion of the bursts of the shells had not reached its opti
mum eulav ta 0041 .sdnuor
mum value at 1400 rounds.
erugiF 8 swohs taht fi eht elbaborp rorre ni gnitacol a
Figure 8 shows that if the probable error in locating a
tegrat gnola eht tnals egnar si decuder yb -eno’yletamixorppa
target along the slant range is reduced by approximately one
driht ot 052 ,sdray eht mumitpo noisrepsid fo stsrub fo eht
third to 250 yards, the optimum dispersion of bursts of the
sllehs si dehcaer 00+!,’dnuora .sdnuor
shells is reached around' 400 rounds.
4
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