USSBS Report 35, Underground Production of Japanese Aircraft

8/3/2019 USSBS Report 35, Underground Production of Japanese Aircraft

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THE UNITED STATESSTRATEGIC BOMBING SURVEY

UNDERGROUND PRODUCTIONOF

JAP~ESE AJRCRJUr.r"0 T 0

RHODE fSL NSJ ST~ COL GLtHHAR'


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THE ITED STATESTRATEGIC BOMBING SURVEY

UNDERGROUND PRODUCTIONOF

JAPANESE AIRCRAFT

REPORT NO. XX

Aircraft Divi ionDates of urvey:

230ctober-25 ovember 1945Date of Publi arion:

March 1947


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FOREWORD'Flte nited tat ij tl'l \tegic Bombi ng urveyW(, estabf hed by tit \!creltll' or War on 3

~ovembor 19, pursuant to IIdirect ive from tbelate Jlr ldent ne e velt, It mission w ns to CODduct au impru-tial lind exp I't tudy of Ute elI ctor our aei-inl aUack on Gel'many, to be used incouuee tion with ail, attn ik on ,Tapan and toIlllJlish a ba i-Col' valuarlng the impor tance

and potentialities or (til' POWOI'a' au iustrumentor mi li ta ry st .r at .c !; ) fo r p lann lng the future de,velopmeut of the nit d tate' armed for' andIor determining Iuture economic policies with1 pe l to UIC national derense. ununary re-(l(l l't lind om 200 upporting I'CPOl't ontainiugur e findiug of the urvey ill Gel'nulny have beenpllbli hed,U15Au

Fr:mklin 1)' Iier, OIw.i"lIIcr'I,Paul H . .. 'it? s Hem,)- ,L\lexnnde,', Vice

hairlll611,Hany L, Bowmnn,,1 , Kenneth allll'aifh,He n i r"il:'o,'I,Fl'lIUk ,~rc~aJllee, ,h"Fred carl, Jl'":\onl'oe K pnght,DI'. L w i R. ThompsonThoodol P. \ I'ight, Di,-cC'OI',~_"altel' Wilds, tcret(Il'!/.

Tbe urvey' complement provided for 300civilian , 3;;0 officers, and 500 enli t.cd men. 'fhemilitnry segment o( the organ izat ion was drawnfl'om the A . J my t o the extem or 60 P I' ' e n l , andfrom Ihe Nal. to t he e x te n t of 40 perc en t . Doththe rmy aud Ibe Na\'Y gave tIle 'urveyall po i-ble a istance in Iurni hing men upptles, trans-port, and information, Til ur'vey operatedfl'Om headquarters tabli hed in Tokyo early ineptcmber 19,m, with ubheadquaete in agoya'aka Hiro hima and ~agasaki, and with mobile

team operating in other pal' of Japnn, theiRhtnd' of (he] aciuc, and th e .d iat ie mainland,ItWIIi! P ~ ibl to reconstruct much o( wart im.Japane 'C lIIilit-ary planning and xecution, en-gagement by cngngem(:nl and campaign by cam-paigll aud to 'UI'(! I -ouably n icurate ,tnti'tion Japan' economv and W81' producti ou, plant byplant, and Industry by industry, In additiontudi wei' conduc ted on Japan" over-all t u n -t eg i . p lan and (he background of bel' entry i ntorhe war- tlae internal di cu ions and negotiationleading to It >1' a 'cepUtI)cc of uncondttional ur-render. til 011 -'Cor heal It and morale among theivitian population the effecli en ' or the .Iapa-n civilian defen e organization and the frectof th e atomi bombs, eparat I' ports will beissu d eovering each phn e of the rudy,The urvey interrogated 1II01'C than 700 Japa-

nese DliJi tnl'Y, government and indu ti-ial o m ials.] t nlso re 'O\' >l'ed and tran ' In t e f l 1 1 I: 1 11Yo . u r n e n tswhich not onl~' have been useful LO the UI'V y,bu l al 0 will furnish data vnluable COl ' olh rstud! , Arrangcmcnt hav been made to turnO\'Cr the urvey' fll to tile eutral Tntelli r e n e eI'OUP, tbrou II which they will be available fol'

( In -the r examina tion and di t ribu tion .

T T l


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INTRODUCTIONBecause f be di PCI ul or :lil't"ll fL ulld 'u riue mauurucumng plan to UII'

dergueund Iocar ions 1)1'0\'(:


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PART 1TS OF NAKAJIMA AIRCRAFT CO.

OVAwith tone qllorrlCli that pl'o\'ided large und~~.lind nrea already dug, The tone wa rer.:111lOft and wOllld thel1!Core I 'ondlly lend fttlol f1 f tile e> let ing eaves .t ell gCII 01' ClIpnU8 on 0o an IIIf the I It ll izaf il lD of two I lA!pnl 'l ltePlan el l ec ord -all and three IIlII'face areas forI t,nd rgl 'OlI lI nre Jth mannfac tu re of one engine t ype, t he. a~an

l'1li d fgnated Ha 4i1, llod I 12 (179;, hp],Thl engine wa the type UROOn the FI'.ank Al'mytighter (.Topallesc Ki ) which was belllg a . 11).bled at nearby Ftl! 1 0 [cel below ground.area Mtacka, however, had an advers effect011 produc t i on . For one week after the area at-1,,,,1.: on 1'1, unomiyn ('it). worker arteudnnc ({'IIoff about ~) p r cent. 'I'her w " " no" ..ion powerintel'l'UPI io n I'Cl ulling trow area u tr ac k s ,Plant o m ials Mid that diOlcult'y in obtainingparts, cluc to at tacks on other plant and to poortI"lu"1~rtllt ion, caused II slowing-down of 111 '0 duction schedules.

Operati nat Difficulties'l'he plant manager complaiued of "ery serious01 l11i ionnl diOlcnlli tbat bad not been over-vome: und nrrouud area' II' re old and damp,~111I " iu g e x r r emo tliscom(ol'l to the employees :th ntmor phere wa foggy from the dampncmaking vi ibili1y "cry poor; all lI)achiuelj wascon tautly ubiect to corro ion unl ' the greate tJl 1 'nutiolJt< agains t it were token, ne diffiCultythat w ar not eueonnter (I during th Will' waseave-ins. although th re have been ' eve ra1 sincethe war ended.

3


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4 5


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Phoco e, 1. Crankc:a.e hop, TomuN pion, ~, 0)-. Work,.G

Plsoeo l O. J.CvUndor head hop. Tomu,," plan! a! Oya Work,.

)

I'llmo '0. 4. C 'Und er a. tnblv ,h7


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9


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troducrionI In eecmber 19-14, Ih .. 'nklljirull .\il'cl'nft 0,, ant rl to dispel' the Ilil'fl'nme produc ion ffl''ilitil'l


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Photo o .13. beet -me Ip r~ (Otomey:u" p l.nl l, h irop"", .

13


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14 15


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~ ~1;.- "-< , ~e . . . .t0Iii:: I '0. .r.> [. .ena : . . .., "0 en-< ~r.>~

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ENGINE WORKS

NO . ARE"'SO"; T. PL"C DESGRIPllOll100 "'1.000 ~1.","1I". I~"d.;j,.",.,101M ~ _ T O I ' : ! ! ! . & ~ ~ " ' ~ ~~~~"bon~~~~~0311 I~ISO - ~ ' " " . . ;n ,0 ~OOO - ..".~Ioo"o s - a re ._...,-,._ ....... '10. ae s e T O < h , t J n . . . . - . _f07 &7.200 ~]~~ ~~~~ll.wttt


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Y -o'/,o ~o ~o

-. . . . .. . . . .~'/100o. . . : .


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C ')o~z


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21


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YO HIMATOn e M 110('1I1Cl~1 nclnlllccel plant '('('II ill ,)"))811

w as rhr l C) "h il 11 al ~U e n l( il lt 1 ,1 11 11 1o r ~ n kl 1j im l lIcwllIc>t1 IICIII' )lnt~lI~'lllIlI' : ! : ? m il 1I0I'lh\\(",1 of!]'ok,vo, 'rhi plant. ",hif'!1 \\'IIK IIi )1('1"'l'rl Iror u th emijn 'YOl'k~,was 0 I>I'l'ntlllilly I I t '< 'OUJI ' 11111111 " ;1111) ' independent.

l ie "(II'ke(1 I or - : !I l )'ellr;: I ll ! I he p rll je ,t I Il Id had2 11I1"j:C 1'0UlII" , 1 ssunll room, 1I1lmCI'Oll eorridnrs,1111(1 tht, !. lId, ra'tolY rece ived

orders to go 1l1ll1'1'!lI'OIlUd IIl1d excavntion W;1started short I~' t ll t' I' t' ,. rt el ', , \, ' sptlton s rIll< '

11IUII('1 ; II'Ms were "OJllpICICtI. nll l tunnels. 'l:whilll'S were set in rhe 11IIInel.ill ~illglc rows,l 'Ol' l'o . . ion o( t ' l lui ) l l l1Put IX' au ie a problem

,111110'1 nt onc e , To comhal Ihi eondi ion it wamude I10( ' l'esllOn"ibilit~' or e nc h workman 10 keephi ' muchiue 1'0111cu"tin!l, To p '\ lit eorro, ion,t1ni .h l '< I 1)III'ls we r e 1,'110 , d I ro in the t un n e l s im-1Ill'flillll'Iy upon Iheil courplerion.

I 'lnn ~ ( ',dlpd /0 1' I h' mnnutn 11m! of a o o 'ogiO(";llel' uronth in the underground plant. with finl\l:I,'>'l!lIIbl,' III "i"pI'I'sed huildin!!' ill aud neat~Inl "U"I1I1I1t, .\t'tlllli fll'odll('tioll, however, con,"i~lt'{l (IIII~ of I1II1"t l' l r c is , , '\ 'l hl d( ,I ' h l' ad~. cyl indeehun,;J . . , ' l Ilt l 'l'nllk~hl1ft ('011111"1lllllll. ", Between:W o


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aeell IlllywlWI't' I In d l lr g l~ ) lI l 1r l w e l ! e illplace hert'.S. power lib tatiun of 1111'00 :?;;O,h,_a

transformers was buil t CO l ' el l b o r the fh'~completed area .Tunnel4:I'o s ec tions \'lIl'iel1 to \IiI t he I IC lO O ,

Tb e e n tran ce s to crlon 1 Iln d G \I I 'C i n 'hcc~c l i f F s at le a t w te e t h igh . 'I 'h \\'ho l< > 'atabli h. ~JDe n t '88 ,,'ell eoneealed e xce pt fO l' a built uprea. of G urCaoo bu ild in g " w ar hOI l~ ',Om $.,etc.) n e al' t be e u&n l l l c ( 'S to ~lIl1lbe l ' 4 '"~II,08hlma II "'88 in IMlt"tc


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(In . .. . llaclon. Yo blau ..u.

2 7


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Ph",o e. 3~. M chino 1001. I.ndln~ In water, l.ondslide had ("r",ed. clam near entrance,

Ph.o e, 35. Th""c ZS().kv..:.......nsr"rmcn!. Y""bltnlltau.2 9


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YAB T KAThe Y"iJulsul-. t uil 'h 'l ll ll l' plant. 10':Ited 6 Ulile .~

1I0r l l rw e st o f ora. G umm a l lr c' fe (' I1 Il 'C . \\ 01 II d j",1 ) cI ' e d Ioontlon of III


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. . . .r.. .

()00 P"fj


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KUKURI

tb.e tuDnels were e at e n -10 tba the machine tooliUialelclil.lre4~J'Jnto a.eh tunnel. After_.I1ftre Inplace itw I n tended to clOlle

and conceal tile entrauce to all but three tunnels,,'III h wouM then become the only ntrances.One hundred tty, foul ' o f II planned 00 maoehlne tool were inNlnl led underground. ' ])hese

machines were Iiued along both ide or the tun-nel lea\'ing an ni le about (0111' r I wide in thonter.TbiBll lant was upposed to mnnuta 1111' engineS

but no actual preduction WI'I' a hieved.These tunnel wet'e among the better on seen

In Japan, They wel'c \'CI'Y dry, well laid out,bad mooth 8001'8, and seemed eoomt t than mnnyothe1'l!(Photograph 3i-40).Kukul'i wa iu JIClcH!(l on 3 ~o\ 'embet ' 19~5 ,

~!II%0.. s i l~~ I ..~

,~ ,IIJ , ( I l l ';:). . .

35


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7. Ma hin h p at Kukuri.


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uce:;;asoC".

Photo o . 39. Kukur l p lant. Two I nl


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'''IN~tocIilulderilP'OlladpWlt 01the tnbl8hltua~ in the h iUa 8e c I a fa qaao prelec.ee la a rea were

~11lC1t1oD goal an oatput of 150KIfa coDjnnetioD ,l'ith a ncarb~p,jmd. plant. 110 ever DO production

NIKODAwas realized and no machine tools were in tailed.tthe war' end the underground plant W8" 4(1per cent complet e, the power in taliatiou wel'e 20per cent complete. and the semiunde rground plan ta ",U per cent complete, with 3 . ' 3 building

erected,The hedule called for total completion of theunderground plant in ptember 194.:',At the time of Inspecnen the tunnels were we . .

and damp, When a ked what precautlon 'l~ain Iworker IUness and machine corro Io n had be '11taken, the plant manager replied tha t there \\':1'no time to IUdy any problem other than that o rgetting the machines underground,Transportation of materlal to and trom the

plant wa e peeted to be by truck only.The interview and inspecnon were conductedon 12 ,:ovcmber 1945,

MATSUMOTOrlrame Work had a

and eemiundergronndvera! miles 80utheaat"'agoya 10 lIat umoto and lofer, to tl1lOSI)()I 't ma-t eri al to the unde rg l'ound $ite, Tran, port to thenndergl' ound plani Irom lI,\1 umoto wa ' by truck,ove r nar row and poorly maintained reads.The schedule called for 50 peecent completion

and the beginning of prodnetlon i n June 1941) a ndlor total completion in Augu1. Due to the difficultlee alrendy enumerated, only ;10 percent 'om,ple tlon was l -eached in Augus t,The Camiliar comment wa again stated here:

the great haste of dl persal left only time to 'Oil'Idol' the basic problem of getting the rnuchincoola underground and out 01 reach of Ih AIlICI'Iean bombers.p ro tect ion of machinol 'Y uga in t orrosion. veuti!alion, and worker hea lth wer e 1)0 tponed , 1 0 : " ntu-ally, l li ts ub ish l hoped to I IOl\ 'c Ihes problems byh eat an d ventilation,Parts labrication 101' Ki- , , Ki-6i, H PJlII, ,1IId'!raqo W'88 to take place underground. II'in~1

,jllrlEtmI)y was to be accomplished in the 150 semi--:uadlaqroIJDd buil di ngs In th surroundiuj; hill~,~ 1V88to be done in miulI(I(ll' , r ound hnil lllap a Dearb u ral niJ'lleld,The date of m.pection of ~Ju.t umoto Wll- )0o e mb er 1946 .

Th OgnlJl i uudergr ouud plan t of )(i ts ub ish j 0,11 Airfl'nUle Works was located 10 miles south ofTllkoka ill ~'oyama pl'cfl . .cture, A miunder-gr ound plan t a t IIannya ll ll lra wa s operated inclo (I conjunction with Ogan.This pl ant was till under construction by thegov emmen t and had not )'ct b e e n taken e v e r by"fir, ubi hi, The excavation IVIIg 30 percent com-

OGAMIpi te but prog toward Q tuul production waonly 10 percent advanced,Tunnel CI'OSS ectlon mea urred 18 (eet by 10teet BCte r shoriJlg bad been erected, The maxi,

mum tunnel length wa 1,150 f ee t . No ma 'binetools had b e e n in hilled.Ogami wns inspec ted on 1 . 'ovcmbel' 194",

NUKATA IFurthermore, Ihe probleur of trnn portation ofboth workmen and product J)r ent d even moreser icus problem t han those which alread~' badcaused {P' at difficulty in other more d~irable10 ation ,Despit e these considemrlons, the plant wa con-

stmcted to hou,' one or their more impor-tantwork' to produ exhaust turbin and fuel injec-tion pump Beginlling 10 .July 1945, mllcbinctools wea laboriou ly pulled up the mountainI'ond b~'hand and roller means and by (he nd ofthe w ar 14 G mil 'hine too l, w e r e in p lace , Inaddition, 2 ;; 3 1 00 1 were, tOl'OI'Iat the base of thehill in shrines nnd choolyards, Almost al l o t themu ' bine too l were o t American make, becauseor the bigh d~reo of a 'curacy required in making[h .e parts..\l'tllal produ lion had not yet begun hut wasautlcipated WIthin a hort time.The cavern and tunnel. were verv dry and in

U11111. plac (.'011(;1 t c floors wer e I l t i d . I~ was notneee II')' to ,1101' "11 the .nvem as natural pil-hn- and the t rength of th 1"0 k it eli were>lIIOleiclI! support.Located on many level hroughout the moun-

tain, the tunnel I'ang d in I vation frolll 6;;0 to800 [eel above sea level. Til' av rage cavern was2() fe t wide whil the height varied Irom 12 to 2()r ee t (Fig. 11),During the CllIl 'lysummer of 19015the - Iapanes

:i:uvy made IICl'ial I' connals ance of the area andreported that the n w road reveal < l th 10 ationof lhe! plant..I\katnni was visited on 19. vembei- 1913,

41

'Phe _'ukallllli underground plant of ~li tsub i hi.I: o. 12- gil r i ne WOI'k , Io iu - m il u th of KlUJQMWJ.l. \\IIS one or thc 010 t UUlI. nal plants to bevislted.'I'he n !(!s$ity fOl' pel'forming II C i-tain amount

or mountaiu climbing to an altitude o( 75 0 feetlent II sunn 'e a ir to Ihe ::oi'ukatani undergroundplaut, '1'he plant \1'0 1I' :e, iblc only on foot upa 1I111'I'0W, recently con tru teel I l id which \\'0wa 'hecl out in many places Ill' he heavy Octobermin,An(liellt caverns, Irom which the people of a

past age extracted III brick, were IIt first intendedby Ihe .Iupan e Nn,'Y to be used II a "avalIII - lin I. r~al' ly in L\JlI 'jl 1945. the :1I\'y started\I'(lrk on making thc tunnels and caverns II, ablebUI lnt in the SIIW month abandoned the projectIIl1d t m-ned it over to , \l itsubi hi Co r lIil'craft-clIgiue productlon.

lIit 'ubi 'hi subcontru 'Ied the COil tmctlon ofthe plant, and the )QUIlll ln), wa to be reimbursed1,ltCI' bS til govemment. Because of the inacee .. ibilil~' of the ' it , it be ame n Ces~!II')' 10 initiatea lul'l-(e ch il road bui ld ing projec i to II I plant, IIresident ;'\1 builclill" PI'I) ! l'om, and II bl' idge con,strucl ion pl'o~I'am to, pan the tcep chn ms to thepluut.Mit 'ub i. h i d id not approve of ukatani but was

lind I .onstant pl'C. sure It-om I he gevernment t obuild II plnut at hi Iocntlon. 'l'he company'sobjection WM bas e l Oil the know 1 dge that, inadd it iou to bei llg inacl 'f!: ;.~ibl , tit plant alsowould pl'obably be out ot produ tion for tourIlion h8 CI\d) ~' ar beeau C o r the hell\.' snow innm-thwe t Honshu (1111' il lg I he winter month,


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c..o::jI'. . . . . .


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0

(5 a r.." mCJ.:) tTl urn ,i ~ N000s

c(/): :J:G>~l>(/)dz",oCl>::0:0- c. . ;n c. . ~- . . . . . (t) .00:: ~ >: . . . , ~ ~ : : . - < ;) . . . . ~_ . . . .

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::I l-:l c -e - g ": : : r ::r ~ s;:l ~ z '0 ::Itil U1 0~ :tJ = ci-;. $ -:::r '"0 - :: s l:) ~ : : . - 'n;' tD ~ ;i ~ =.." . . . . :: s. . . . :: s o 0..;.. l:) to - ~ ~D t:I . . . . . '"b :: s :: . c. .;; zi: ;:, . . . . . - 0- l:) B U1 00 e, ~ . . . c . . a ~ . - , : . . . . *~ c'= tilt:I '" ..-; ~ = - ~ :: s s til0- 8 !::) =l) ';:l . . . . . ::;:.t< t:l0Q '0:; ~ ::: * z M-el til . . . . ~UJ tl) -~ (JQ ~ 0-: f1 Co -e = .-: 4 : : . - '"0 a ': ~ ~ ~ - Il) Q"--: ~0 . . . . l > - : ! ? ~ ('Ii- - t:I c = ::I 0 l -e l. VI Q" . . . . . 5' ('Ii ~ fA. . . . e-e- .-t- . . . :;1 tl) J -3~ = . ", 9!:I I : : : r !:I tD ::r- ~ 0 . . . til lC 0 tD < : : > ": -e> a.. "0 . .. 7;" > r. > 8 -.; 8 - 0- . . . .l ~ 5' ~ Ill) :: s1 cr l :: s O 'Q c;' I'D$ - ~ . . . . . ;:" '< ::r_ 3. ::r n ..;. _,.S : ; : : = 0 > ;;; cr:" 6 c. . ;;; " " 0- til ~. . , tD c : : r Q. e . I~ . . . . . tD 'd - . UJ. Cl g - C ::I P: ~JQ a 0 ~ 1 -3 tD 0- 0C c : : r ;l =:r ~ . . . . . !i;' = . ~ 1: 1 a- n> .-t-> 1: 1 (p


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4 9


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50 51


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PART IIIMI OR AIRCRAFT COMPA IES

,ide\\'all: adjoin in ' lhl' hllildin~, Thi work lind11( 'C1ic'nrl'i(;d ou t at night 0:1 10 con cal thewhole 0P~ I' I\ tion . 'rhl' h eavie r- a na 'I l il le ' were intil(' rllil'd bas 1 0 I II an el the l ighter one ' in the~ t O ll d bn 'ClllCIl1.

11 1 great coutmsr to th tu nn el p lo ll" . ruesbn ('UWnt oIT(l1 d no 111111 ,n l e .p 1't11;01l1l1 pl'ob.I(>III~, WCI" c le a n , I ll :h l, (h'y. nllel (!m('j 'Ill. ].lIrtber.I II IJ I' (: no ext mal ( :\ 'i denC!l \\'0 \'i$ible to the photoil l lcl 'I )J 'CIt 't of I he aetunl work taking plnee here.TIIi' plan t w as v] it don 31) tollel'194;;,

S O G O DEPARTME T TORE PLA T OF THE UMITOMO COMPA[ YI II O S II I. :u . t hl ' "(!(()JId an d tlill'd hu sem e n ts of

!be go ('0. Depm-t men I , 101'( >\ \'el'(> 1I~( 'dh~'heunlitOlllo o, (01' tlu' machining of j ll 'Op(, lIel'

part,Not 'tri ' fiX un lIIl(]C'I'gnlUlld JlIIIIII III ' 4 0 ' "lie,Dl en ! were ill'! lcd( >d to eomplet the Jli(' tm '( ' ofthe \'IIti!)1I lypc, of underground i n t al ll ll iO I l"A total of J(j7 rnneuine tools OIX? I'H I I I h I 'C fOl '

IlIJeI'iO(1 of 3 mouths ill what nplll!m' d to hc fillorde rlY an d w ell-m an nge d prodllct ion l i ne .The machine tools I llul been lowered imo Ih

b llse me nts IIIJ'o IlS h h ole ' th at had Iw ell cu t in Ih.

The Ilundu underground plant of the IIIl1itOOlOCo. W8 I I 1>81t of I he 11( '1\ \'01'1: (I f nnd('I'~I'I)1II1t1plallll< sourhwos t of '1 '11t11l1of )1 i t . . .uhishi whit'h IIdjo in ed it. 1'hct un n e l \V I'C cnlm'sed ou r of tu n n e ls w hich hadb o o n dug ))1 ' \ ' 1 0 1 1 > 1 1 ) ' to I u r u i s h l i n d Io r '111I"I"i\e.~,Freqllcnt sho l' il lg , cement "PI'II)' 011 the wall . ..drip gll!lI'(l;; 0\'01' the machines. eoncrete floors,

Mlopillg I ev e l . . , Illltl (II n illllj.:(! !!"llN'S we r e char-n e te r il lt iC II o f t hi ' plunt, I'nllll>int: \\,11" ne e "ar.\'

HA DA011 o ~" a~ io ll 1 0 " 1 II 0\ 'e th \\ ';111'1'. (Photogrnph,1 ;)1.)'l'here were 110 mil eommuuicaueu 111111101. "

at Hisai and the machine were moved iu byhnud,

1~1I1J1I'~ill!! ( If tunnels I I gall in )[;\1'111111u:1I.500 employ ':lnd (;10 muehine tools..:!:; omployees and 271 mnt-hines wer I II work.

Handa \\11. 10 1111)(111(( III 'olwllel ' purts, Th,plnnt W;J, i ll ope rn ti ou b ill on ly 11 rC\\ ))1l11 hadIw~n Ilni~hed.

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~ ":r0(5z Z?" " " " " "'P ?>" ' . . . .:l ::l. . ., ~I) .,:l o .,~~ :z :z : III~ :: JQ"" !I I


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in ... . d mines near T.u City.

TAl


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K AW A SA CK I D IS PE RS AL P OIN T

L.-JI-- IDEi~~rrL___jL_jLII II

NOTES:FACTORY AREA FACTORY NO.1. 100,000 SQ.FT.FACTORY AREA FACTORY N02.200,OOO SO.FT.AVERAGE TUNNEL WIDTH. 18 FT .AVERAGE TUNNEL HElGHT-14 FT .COHSTRUCTION-CYPRESS LOaS REINFORCED IN DANGEROUSSPOTS WITH CONCRETE. SOME TUNNELS COMPLETELYCONCRETE. APPROXIMATELY 100 FT. BETWEENTUNNELS 1,2,5-

SCALE: 113000o 200 400

(00 300FEET- ---


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:g "'tI., :r08 0Z Z? ?Vt Vt~ !'ltn Q'~ 0:0 s . . . . .8'" " "C n:r. . . . .0 :: I. . . . . Il>:r t1":. : 0'C~ " "n . . .Il> (J)? Il>?


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6061


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Phoco No. S8. .n plant. (Noc~ e len Ive horina.)

6263


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HlRO PLANT OF 11TH NAVAL AIR DEPOT CO CLU 10

UNDERGROUND PLANTS

PIaD8 for uaderpoUDd 'productioa were made.111 pm 19. Col l8 traetioa aad coaf8 l1 li oa of'the t 1ume Ia we r e begua ID ovember 19U. Theam IDOftlDeat 01 equipment to the uadergrouadtmme1 ua .JaauIll'11946. Th e priaelpal uader-pouad tael lJt iea 11'81'8 eoaverted from a largeuadupouad haapr which had been built ID1940,aad aa adjolalDg road tuaDet ctoal productioa. .. .. . b eg ua fa tHIe ta ua eJa at the end of Jaaulll'1~. It ..... plauaecl to move all the 8IIUll ler m a o

I ehlaea to theee tuaDeI8. Oa.halI of the remalalag)up maehlaea we r e to ata11D the 81Irfaee buUdIDp at BIro hi1e the other half were to be

~enceCheck

moved to Takiha l' a. Th is movement wa s to becompleted by June 1946. At the time of th airraid on Biro on 5 leay 1945, over 90 pel' eot 01the amall and mediumsiv.ed machin had alreadybeen moved underground. At the end of tIle Wiltabout 99 percent of the machine' had he n in.tailed in the underground plant .In June 1945, t he Hiro _ al'Y Yard comEnted its

lacll lUea for making marinc eugtnes to t he manu.facture of aircraf t parts. Its machin ' were in.eluded in the underground d ispersal. Plana Corthe&'e underground pl ant ailed COl' p roductionof 400 engines a montf by API'il 1945.

Japanelie underground in tallat iOI1 wereto o late lor th em to be able to ave the pro -of aircraft. In any event, til ii' xi tenec

not have overcome othel' problems uch as01 "ita) raw mnterinl . and Iuel,

methods do not rCI'CflI anythingi new or tbat is not all'ead)' kno vn to theengineering profession. Only the proru ion

CO\'eIi, and mine i impressive.3:41lker'llPt dampn wreaked havoc with preci-

ma:cbiinell 'l 'and with the health moral lindof workers. Airconditioning and wlIterwere necessary lOI' any long period ofif machinery wa to be protectedand C01'1'0 ion il>ndtiLL be in lie.worker need to be fortified with an

diet. WOl'kel'$ al 0 need plenty of lightun Jamp would probably ho\'e beenthe workers.l J " I I " . " " , , , , n " production probably uffel'ed Irom

ftee and imple tran port uch as is~GIi !l ab labl len a compaer, wel l-p lanned urf ace rae-

uadergrouud tunnel through air photo iuterpre-tation, Postwar photogl 'apby and interpl 'l llat ion,even when based on infol'Dlation upplied byUS B ,W88 unable to find mo t of the enunnat the location that had been tudied b. t: B,And it W88 impofl8ible to slate how extensive anunderground plant migh t, be or what activity wabeing conducted i n it.The principal way of learning about under

grouads ,,'ould seem to be by ) : 'OW intecrogat iou,augmented by alr photograph .

Interdiction of higbways an( l l 'I lih'(Ulds IClldln~10 1111 l ind I 'g round J 'e tar dcd product ion bv ob.tructtug the receipt er mater ials and rll dciil'CI'1'of ftni!;h d 'ood, D truction of electrle P()WCI'SO\lI'Cesm i h have had the same ffc t.. j'he P~'illcipal ad\lant ages or an uncler{,'1'oundIn tallatlon ar that it is hard to f ind, rnnk IIvery poor t .a l' ge t and would Pl 'oh llbl . 11 Me (I'oman y weapon u ed in th e e co nd W O)'lcl Wnl'. lIeal,'ga' would make an und rgt'ound IInlcunble bntcould be COnntCl'ed by air pll1'ificaliou dc\'icc .J a . te rl a would be e ff ec tive nga in t worke whoso\' ital ity and resistance bad been lowered hv work.Ing nndcrground, l lowc\ 'e l' , i n p it e or the d i ' adv llotage~, it wouldC1l1 Ild\'tmtagcou (01' any nation to I)Ul SOme of

its more vi tal pl'oduction fa iliti .into ad '


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GENERAL ARRANGE NT OF ASAKAWA (UNDERGROUND) PLANTCorrec ted 10 13 JULY 1945


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IW O R k S

L AYOU T O F Y ABUT SU KA P LA NT

U .s . S TR AT EG IC ~ smvEyUIlDERGROUND PLANT

YA8UTSUKA"..,J100".... ..& 1,)


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5 C o I L E IN

l N E R G R o l N : > PLANTOF

N A K M \ 1 A C O .L~I(lGK\'VAltfS_ 5%n.1O-"~ Sl) l( l' lDUIS411HA~. tlllD ft: 1OQI.$ H S V o I J " I P J

~l


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IPu i

SETO_._-PUNT OF _ _"

USSBS Report 35, Underground Production of Japanese Aircraft

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Transcript of USSBS Report 35, Underground Production of Japanese Aircraft