APPROVED FOR PUBLIC RELEASE -—--—-— hJ!!Llqs-4i6 C3akta. . The. energyrekased during. the. exploeimoould shooknave %Telosity mwuwment beo?mse ofthe difficultyof. under-mtiter

‘$-?

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UNCLASSIFIED

This cbwmmt QOtlt4Y.189 P.M p. **.

W* Iktxnekr



ABOUT THIS REPORT

This official electronic version was created by scanning the best available paper or microfiche copy of the original report at a 300 dpi resolution. Original color illustrations appear as black and white images. For additional information or comments, contact: Library Without Walls Project Los Alamos National Laboratory Research Library Los Alamos, NM 87544 Phone: (505)667-4448 E-mail: [email protected]

CROSSROADS TXWUCAL Ii$ST@ZJ?MTATZOMRiWWi2

TEYM A & B

15 October 1946

Projmtrk.: Ix-1

●Subjects Fa6taxPhoto~p~

Preparedby: Bqr. Briaaw

Ho (3.Hollow “

JMsm!H

No photo~aphic record of tlm nuclear

for test A becaueeof the delswin startin$tha

A satbfactoX’y phdo~apkc record of

exploeionwas obtained

aanw’aa● ~

test B was obtainedfx%m

Camras

Jet md

at the Erqyutower station, The space-tti rela’t~ona for the water

cloud fomatlon were obtainedfrcmthem fil.me~

/JlkL&#4,@

.

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1.

n.

31L

3V.

‘V*

n.

SUBJECF

Ultmduatlm

n?mx

MO”-ao-.mmm--.-.-. ----m-” -----.

PA(%

1.3 Test Able1.2 Test Mcer

Ihctruncxrtsand Equipnent

2bl C&nerae2,2 Ccatrol Equi~ent

b8tit6 ------------------.----------.-..—

S.1 !test4bLe%2 Test kkez

%2.13.2.2S.2.3

C(%mhlui(ms

WaterWatercloud

JetLevel CkmlChamber Effeot

----. -0”---- .--.”-- .-.-. ----” -------

4.1 Test Able4.2 Test Baker

Roocmmendaticmu

Group Mrsonnel

.

n.-.. n9.n-mu-.m ---*----m----

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4

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-.--. -...” .”-----

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--0-- 0--.. ””. -.---0

.9--.”-. — .------

Camera Specifioaticms for Test Able.

camera Specifieaticms for Test Baker

Water

Wit er

cloud

Cloud

ikter

hater

?Jater

hater

Jet Profile

Level Cloud Profile

%amber Effoot--l%arlyStage

Ckamoer lifft3ck--LateStage

Jet Spa6e=-Timo Gre@

Jet VelocitA Graph

Leml Cloud Space-Time Graplh

Level Cloud ifekOity &a@

CsmeraTower

Camera In8taUat ion

Relay Raok for Czxmma Coulxol

T5ming Signal Recei%ers

Storage Battery Fotir Supply

.



.

T-0 Introductions

1.I Test Able. The amount of energy released by”tie Atomio Bomb

explosicm -S to be detemined. The velooity of *he shmk mm provides

● neasure of”this eaergy. A photogr+io record obtaimd ta’”omhi@ 6peed

mbt~oa ptoture earaerse

providesthe nooatmary

1G2 Test Bak+.

not be determined by a

operat3ngat 1000 framea per tmecnd or ftkstor

akta. .

The energyrekased duringthe exploeimoould

shooknave %Telosity mwuwment beo?mse of the

difficulty of under-mtiter photography. A photographic ?eoord m to be

obtainedof the prk of’the explosim vlaible above th~ mater 6urfaee~ ..

IL Inslxmmentaand Eqpl~ent x

2.1 A @Wp” Of )?astax16mm

ln6ta~ed

explostuz

and Enyu 3slands. See

each of the oamerasU?ML KodakCixteE U3mmeamerm mre also

at the Enyu station to obtain a %o hour reeordof the ●

and subsequent oloud. The possibility of a Iergo err~” in

dropping the bunb for Tmt Able led to &he instillation of a wide anglo

OSMO= tith m*~ fik. This OSUNMWmu3d remrd the explosttm U it

oooured as muoh as 1-1/2 miIes &an the target oonter and had a time

resolution betterthan l/iOnlllfuooondo A LiitohellS&mm eawem mae

also $nstalled in emh of the towerso

Faot- -d mide engle, eonttiuousmoving film oamerae were also

inetulled and operated in AM? photo planes by Army peremnel.

T?onnalspeed 16 and 35mn oammas were installed cm board the AV.17

to obtain a piotorial reoord of both escplosims.



●● ✎ ● ●m-

::: ●*e :., 9 *.**amlliii.0. :O.

● * .** .:. ● .*● :,.:* ●

● *9 ~b

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2.2 Power forall cmneras and oontr;~”e~;i~ont at the tower

● ’ sta+ims was obtained frcm storage batteries sinoe gasoline powe??od

generators were fmad to be mreliable. A reltiyraok at oaoh s+saticm

emtrolled tho operationof tho oameras. The osmora control relays

&igL%1 rooe$vfigbox and were openedby switeheawhioh wereectwabd

The oamezas XWM for ~rious periodtc of time fkm 1.S see *O fifty

minutes depending on running speed and film oapaoity. %sWl?Ls XwrQ

startedat .6 em, -2 ma, or 4).7 seedapendingon the total rv.tmfxtg

time.

All cameras operated proporly but the %iming si@uQei were suoh

as to startall the rmotely controlled oameras about 16 aeoond.sc&w

‘thestart of the nuolear @xplosia. The developed filns from the high

speed oameras sho~d no traoe of’an @ago sinoetie expormrowas mut

reeord for the period of 16 see to 1-3/4 hours● Tho 6auI@rIM3cm th

of the explom%an.As far as knownnom of the hi~ speed OSWYIM!

3.2 TeB~ Bakert—.

All esmwas at the IiMyustatioaoperated properly but,w+m%”operated..0 . * ●*

a ‘C::;’;[ii::.



t’d available fOX’KlIi6 t9St.

by 100al interfere.nee at the

fi.xould haw left +he r01a3~

+ould not start the oarerae~

The photogra@ic reeord

@loud cover above 600 meters

If the reoyoleconnectionhod been op?wkd

tim the -2 minutesignalwas reesi.ved

pnol inoperative,and

obtained *s yirtiallyobaourd by the noswd

altltude~ The irragular water <et sad

cloudfs’dm made aeouratemeawretientdiih”ioult● In everycasithe

-rmximwsvelooitywas measured. The data is presgntedin the formof

5*2.1 Wter Jets

The nrogr63s of the

dearly shown in Fig. 2. Thk

camera tilt or perspeet5W

velooitiyplats wore dtained

water jet for the first 1.6 seconds is

jet assumes a cone shapein its laterstsgos.

The lateraleqansia of the apex of t!@a ooneat the -ter Level is

relativeXy small, The vertiesl measurement were sade near the verti~l

throtighthe exploskr. oenter but in ~very oaee the h5 g$e~t point-s

selected. Neasurtwmts were also made at an an~le of about28 ogrees

I

trcm the vertioal as ther~ ws an ap;$x+mntparticle inotiauin t is direotiea.

Tinevery irregular ocmtours bad to conctderabl? unoextainty bu a reason-

ably ranoathourve iu obtained. See Ng. 6. Later etagesof th expansloa

of this water ,jetare obsoured by the fog formd by the oloud o* mbcr

e sil’ect. A velooit;ycu=ve, I?i:?.74*:=~:.L~j=ti?d:f=O~:the S1O-M f the8* ●●✚ ✚ ●✚✚✚ ✚

● ●o: ●:* ● 9* ● *9

● eoe ● **●’e ● ● ● ●m*● - 8

● ‘:0: : ● .-.’

●0:,●

::9*.



Wm!?!marms Of Fig.60 Direct %#&&& ~c~e or$gimd film glvsa value

● ::of about M)O meters/seoon~ 2n$x#t yO~~~I$@O:hdnous front when it first

●

appears above tho ~ter eurflms. The lminous frmt persisted for about

0.1S seoond. The ~t is dme shap~ up to about 1/2 mocmd and gradually

changesto whatappearsto be a flat ring shape ti about 2 seoonds.

3.2.2 Water Level Cluuda

A large e~roular O1OWIof mist or sprayspreadsout overMe

wktermrfioe frauthe explosicm oenter. The ebud remains cm the mtes

surfme for neveralm3xnatesand then liftsto the prevailinguloudlevel,

the bottcmbe$ngat about 600metersaltitude. Ilhen the ~ter $et spray

fills back to the lagoon it undoubtedly marries along with It a large

mass of air ● This mass of air probably oarrles the finely divided inter

parthles in a nuspeneim and spreadsoverthe inter su~oe rad5Mly

fran the explosion cater to form a oiroular oloudabout four miles

k diameter. As the @loud 3Mt8 it is seen that a heavy rah prwaile

render$t and this persistsfor an hour or more as the olouddrif% to tha

northwith the prewaili.ngwinde. Figure 3 shows successive profiles of

this oloud fomaticm. Pluts of growth and velooity of growth are shorn

in Figures 8 and 9. The oause of the kre@er velocities of the mrth-

8Mt OhUd fralt i6 not a~t.

3.2.3 Cloud (Mmber Effeuts

About 0.76 se-d after the start of the 8xpk)8i= a rbg 8~p8d

fog Oloudis seen

S&lmeters. This

veloo~ty of about

to developaround the uater @ at an altitudeof about

fog oloudoo&Snues to grow at a fkirlyoomstant

3W meters per seoond (soundvelooityti air) uutil

it has formeda oloudof aboutfourmiles d$emeterin elwen seoonds.

Duringthe initialstagesthis oloudis hemispher$oalb shapewith its

baseabout 200metersabovethe Iagg$aeoqu-r .+t1.2 Seoondsfog● **.** .*.● 8 ● *●0.: : ●:**

!● 9

● ●o: ●:0 900 ●:0 ● .●

-o~oq : ●.e .0. .0: ..:

● ** ● ●

-:; ‘“:



● e ●***.*= ●

:~ ‘MdllikBMarta to f’om stiultanwus&y#u8j.a?afqAhy.~%er ewfaoe and $ustbelmr

● ::.::.::

m

the hcu@phere baseand th&%&Mly .fiX!a4kb spacebeneath+&e exist~

oloudand mergeswith it so as to W fnd~stti=-ls-ble afier S seoond6-

A8 the fog aloud grows zadtilly 5% ap~rs to lift trcm the water 8WAWJS

probablyby evaporatha of the f’og~to u alt$tude of aboua4)0 iueter8.

‘MM madman aititude for tog fo-tion ta not Ws t- 800 ~tere but ia

diff:oult to amertein bmwe of the obsowiag olouu~ Profiles Of *M

NO &format San was obtained for determinatka

expans~cm of the ball of tire.

4,2 Test Bakerz

of the rate of the

A goodphatogm~ia reowd of the explosirmwas obtaiued fraa the

@ En~ Islandstatims The 5nitialw@Aoa% velocityof tho water jet SS

1%X3~100 m.p.f3. The jet is Iwninas and resemblesa shookwave frcmt

tit first but &ter the hminow sua?faoe38 wxy &potty ae it d=W6 aud

rern=bleo *he bunAnc of W?Mmdle IMX*QFtiU RI*PS *M $r~ ~ the

LSX 60 was the souroe of this flame. t?he~ beocmes bu3boue and qppeara .

to vat% at %*6 *W emter. ‘lhiseauees it to assume a oon-l~ke @ppear$MMo

WithinS0 seeondsthe upperporticaof th~e conehas expendedto form a

cloud2000meters in diwmter and ha$ roa&ed a heightof wor MOO mMw@.

A portionot We ~ter desowls to fom a surfatm raloud,4- 5 miles h

dhmter, fiioh Aarts to rise in 8-4 minutesand giwea

MXnwe ~tietonn.

The shoskwawe In air gives rtseto a cloud chamber

●of’ the fog fomaticn velooity gives values apprattig

●* ●m*●:0 ● ●0.m. ● ● :00● 090 ● e::-? %1: : ““ : Q.

●** ●9* ●D* be

● *** ●ee●** ● ● ● ●m. ● ●e:

~i’

rise to an

fog. M3asurmemt

Qti soundVO~OOi%y



NwR!iimet 811 points● ●* ●:0● **9:.:- ●*e

●● ● ●00:.::

● .:● : ●

8

.*

●: ● ● O* :e. ● *

v. Reoemmc@ati~e for Fu;ure Tests c..—

It is olearthatthe tight soheduleand mmmquent hasty prepara-

tion for Operati~ Crossroadsled %o many of the diffhikties

emovntered. In a futuro test adeqwzte notiae should be Riven so that

pkns em be oarefullyexeeuted. A speeifietine,not lessthan two

reeksbefore the test, shodd be set after whichno more ohangesin the

ir@ta31atIons would be made. ThereafterQ series of tests should be

startedto determine reliabilityof ope~tia of ogtipen” and tM

shouldbe allowed to make ftial adjustments of equlpsent~ St would be

desizableto have four osmera stationsspaoedat about SW degrees around

the target so that a better oheok oouldbe obtahed botwoenthe wwioue .

filmrecords.

m VI. Group FWsulnel;

The followiagpeoplespentpart or all of theirttie a the lWstax

13MJtogqhy I?rogralu.

‘Jaoki% ht)y &rlyn Brkner J. Oarltm Eoogterp

A3bert A. Bartlett Ralph L. Conrad (iillmiWaite

FelixE. (le$ges

.

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FXG. 10 .- Generml view of FastestEhoto~@y towerand sand oover~qucmwt storagerocmand work shop. ‘i’hetarpwlin justbelowthe towareab proteotsstoragebattesiesand ohsrgezThe OUXW= post ie in the Opp-%te &%& of oeb.

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Tb MltahellMO fep.saownorais fshomcu the right. CumOXMfk60the olosedport of tho uab~



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FIG. 12 -- Relay rwk for controlof al~ oamrmzsis sh~ at lei%.T$mSngMght pulsegeneratorsare h wood oabinetat rig$tbaekgroand.I&asterpowsr controlswitohand distrib?zticmbox are cm rigti.

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Documents

APPROVED FOR PUBLIC RELEASE -—--—-— hJ!!Llqs-4i6 C3akta. . The. energyrekased during. the. exploeimoould shooknave %Telosity mwuwment beo?mse ofthe difficultyof. under-mtiter