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Given  By 
U.  S.  SUPT.  OF  DOCU^fENTS 


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THE  UNITED  STATES 
STRATEGIC   BOMBING   SURVEY 


Underground  Production 

OF 

Japanese  Aircraft 


REPORT  NO.  XX 


Aircraft  Division 
March  1947 


p^f 


THE  UNITED  STATES 
STRATEGIC   BOMBING   SURVEY 


Underground  Production 

OF 

Japanese  Aircraft 


REPORT   NO.  XX 


Aircraft  Division 

Dates  of  Survey: 

2  3  October-25  November  1945 

Date  of  Publication: 

March  1947 


M(a3 


A 


0.  S.  SUHtKlWIENUtNf  Of  UUUUMtNCt 

JUL  19  1947 


This  report  was  Avritteii  priinavily  for  the  use  of  the  United  States  Strategic 
Bombing  Survey  in  the  prepaiation  of  further  reports  of  a  more  comprehen- 
sive nature.  Any  conclusions  or  opinions  expressed  in  this  report  must  be 
considered  as  limited  to  the  specific  material  covered  and  as  subject  to 
further  interpretation  in  tlie  light  of  furllier  studies  conducted  by  the  Survey. 


II 


FOREWORD 


The  United  States  Strategic  Bombing  Survey 
;as  established  by  the  Secretary  of  War  ou  3 
lovember  1044,  pursuant  to  a  directive  from  the 
ite  President  Koosevelt.  Its  mission  was  to  con- 
uct  an  impartial  and  expert  study  of  the  effects 
f  our  aerial  attack  on  Germany,  to  be  used  in 
ounection  with  air  attacks  on  Japan  and  to 
stahlish  a  basis  for  evaluating  the  importance 
nd  potentialities  of  air  power  as  an  instrument 
f  military  strategy  for  planning  the  future  de- 
elopment  of  the  United  States  armed  forces  and 
or  determining  future  economic  policies  with 
espect  to  the  national  defense.  A  summary  re- 
lovt  and  some  200  supporting  reports  containing 
lie  findings  of  the  Survey  in  Germany  have  been 
ublished. 

On  15  August  1945,  President  Truman  requested 
hat  the  Survey  conduct  a  similar  study  of  the 
ffects  of  all  types  of  air  attack  in  the  war  against 
'apan,  submitting  reports  in  duplicate  to  the 
Secretary  of  War  and  to  the  Secretary  of  the 
Javy.  The  officers  of  the  Survey  during  its 
apanese  phase  were: 

Franklin  D'Olier,  Chairman. 

Paul  H.  Nitze,  Henry  C.  Alexander,  Vice 

Chairmen. 
Harry  L.  Bowman, 
J.  Kenneth  Galbraith, 
Eensis  Likert, 
Frank  A.  McNamee,  Jr., 
Fred  Searls,  Jr., 
Monroe  E.  Spaght, 
Dr.  Lewis  R.  Thompson, 
Theodore  P.  Wright,  Direrfom. 
Walter  Wilds,  Secretary. 


The  Survey's  complement  provided  for  ;JOU 
civilians,  350  officers,  and  500  enlisted  men.  The 
military  segment  of  the  organization  was  drawn 
from  the  Army  to  the  extent  of  00  percent,  and 
from  the  Navy  to  the  extent  of  40  percent.  Botli 
the  Army  and  the  Navy  gave  the  Survey  all  possi- 
ble assistance  in  furnishing  men,  supplies,  trans- 
port, and  information.  The  Survey  operated 
from  headquarters  established  in  Tokyo  early  in 
September  1945,  with  subheadquarters  in  Nagoya, 
Osaka,  Hiroshima,  and  Nagasaki,  and  with  mobile 
teams  operating  in  other  parts  of  Japan,  the 
islands  of  the  I'acilic,  and  the  Asiatic  mainland. 

It  was  possible  to  reconstruct  much  of  wartime 
Japanese  military  planning  and  execution,  en- 
gagement by  engagement,  and  campaign  by  cam- 
paign, and  to  secure  reasonably  accurate  statistics 
on  Japan's  economy  and  war  production,  plant  by 
plant,  and  industry  by  industry.  In  addition, 
studies  were  conducted  on  Japan's  over -all  stra- 
tegic plans  and  the  background  of  her  entry  into 
the  war,  the  internal  discussions  and  negotiations 
leading  to  her  acceptance  of  unconditional  sur- 
render, the  course  of  healtli  and  morale  among  the 
civilian  jjopulatiou,  the  effectiveness  of  tiie  Japa- 
nese civilian  defense  organization,  and  the  effects 
of  the  atomic  bombs.  Separate  reports  will  be 
issued  covering  each  phase  of  the  study. 

The  Survey  interrogated  more  than  700  Japa- 
nese military,  government,  and  industrial  officials. 
It  also  recovered  and  translated  many  documents 
Avhicli  not  only  have  been  useful  to  the  Survey, 
but  also  will  furnish  data  valuable  for  other 
studies.  Arrangements  have  been  made  to  turn 
over  the  Survey's  files  to  the  Central  Intelligence 
Group,  through  which  they  will  be  available  for 
further  examination  and  distribution. 


Ill 


TABLE  OF  CONTENTS 

Page 

Inlroductioii  1 

Paut  I         UndergioniKl  Pl.iiils  of  Xak;ijim;i  Aiicraft  Company 2 

Part  1 1       l^iulei-yidiiiid  J'laiits  of  JMitsubislii  Aiici-aft  Company 33 

Part  111     Minor   Aiiciaft   Companies      53 


IV 


INTRODUCTION 

Because  the  disspeisal  ol'  airi  rail  and  engine  manufactuiiiig'  plants  to  uu- 
(lei-gi'onnil  locations  proved  to  he  fai-  nioi-e  extensive  tlian  had  been  suspected, 
a  special  sttidy  of  undergiouml  phints  was  undertaken  by  the  Aircraft  Divi- 
sion. Lt.  Col.  J.  W.  Fredricks  was  assigned  to  the  task.  He  made  extensive 
preliminary  investigations  of  Munitions  Jlinisfry,  Army  and  Navy,  and  in- 
dustrial records,  followed  up  by  tiehl  in\estigations  at  many  underground 
sites  throughout  Japan.  A  summary  of  his  findings  ajiiiears  in  Section  II  of 
the  Aircraft  Division's  rejioit  on  "The  .laijauese  Aircraft  Industry".  The  fol- 
low pages  comprise  a  series  of  "thumb  nail"  reports  on  several  sites  which  he 
visited. 


714387—47—2 


PART  I 


UNDERGROUND  PLANTS  OF  NAKAJIMA  AIRCRAFT  CO, 

OYA 


AVlien  Allied  ;iir  attacks  toward  the  end  of  1944 
made  it  evident  to  the  Nakajima  Aircraft  Co. 
that  their  plants  were  vulnerable,  plans  were 
drawn  to  disperse  them  and,  insofar  as  possible, 
place  them  underground.  Oya  and  Shiroyama  in 
TawancliiGun,  Tochigi  prefecture,  four  miles 
northwest  of  Utsunomiya  were  selected  for  the 
dispersal  of  part  of  the  airplane  engine  manufac 
turing  facilities  of  the  Nusashi  plant  near  Tokyo, 
and  later  for  the  dispersal  of  most  of  the  air- 
frame manufacturing  and  assembling  facilities  at 
Utsunomiya.  This  works,  both  engine  and  air- 
frame, was  the  best  developed  and  most  extensive 
of  all  the  Japanese  underground  plants. 

The  area  was  selected  largely  because  many  of 
the  surrounding  hills  were  already  honeycombed 


with  stone  quarries  that  provided  large  unde 
ground  areas  already  dug.  The  stone  was  rel 
tively  soft  and  would  therefore  readily  lend  itse 
to  changes  or  expansion  of  the  existing  caves. 
Plans  called  for  the  utilization  of  two  separa 
underground  areas  and  three  surface  areas  f 
the  manufacture  of  one  engine  type,  the  Japane 
Army  designated  Ha  45,  Model  12  (1795  hp 
This  engine  was  the  type  used  in  the  Prank  Am 
fighter  (Japanese  Ki  84)  which  was  being  assa 
bled  at  nearby  rtsnnoiniya,  and  later  was  to 
assembled  in  other  underground  works  in  t 
Oya  area.  The  following  table  gives  details 
the  engine  works,  and  compares  plan  Avith  acco: 
plishment : 


Location 

Utilization 

Area  in  square  feet 

Equipment'                          ■ 

Planned 

Completed 

Planned 

Installed 

Toraiiro  Moiiotain  (undernroiind)  .  .  . 
Renteu  Mountain  (underground! .... 

Machine  shop  and  heat  treatment 

Machine  shop  and  assembly  sliop 

177.000 

212.000 

:i .  5  10 

16.500 

21,200 

1U,000 

118.000 

2.120 

1,580 

21,200 

991  MT  and  11  Fur 
446  MT  and  .1  Fur 
36  Fur 
14  MT 
3MT 

347  MT  and  4  Fu 
238  MT  and  3  Fu 
7  Fur 
4MT 
1  MT 

Tage  Mountain  (suri'ace) 

\ssenibly  s()op 

Total 

430,240 

313,900 

1,454  MT  and  50  Fur 

590  MT  and  U  F 

'MT  Machine  tool     Fur  furnace 

In  addition,  there  were  five  surface  buildings 
with  a  total  floor  area  of  24,200  square  feet  in- 
tended for  use  as  warehouses  and  offices,  and 
seven  separate  groups  of  buildings  with  a  total 
floor  area  of  342,000  square  feet  intended  for  use 
as  dormitories,  dining  rooms,  etc.  The  Kanunui 
factory  was  an  old  rope  factory  about  4  miles 
away  from  the  other  sites. 

Excavation  was  begun  in  January  1945  to 
adapt  the  quarries  to  their  new  use,  and  in  March 
1945  some  of  tiie  maciiinery  was  put  in  operation. 
Tlie  first  engine  was  completed  in  June  1945,  but 
the  over-all  plans  were  not  completed.  Before 
the  war  ended  approximately  one  third  of  the 
planned  area  was  in  production. 

Five  shafts  had  been  sunk  for  quarrying.  Cov- 
erings were  put  over  them  to  keep  out  the  rain, 
and  also  to  camouflage  the  position.  One  slant- 
ing tunnel  was  excavated  for  communication  be- 


tween the  various  levels.  Labor  for  digging  w 
l>iovided  by  a  naval  maintenance  unit  which 
rather  unusual  because,  in  general,  there  appea 
to  have  been  a  lack  of  cooperation  between  t 
Army  and  the  Navy,  and  this  plant  was  intendi 
to  produce  only  Army  engines. 

Organization  and  Operation 

The  factory  was  under  the  general  nianag 
ment  of  Y.  Nagasawa. 

TJie  Toiimio  jilaiit  was  intended  to  niachii 
<\vlinders,  cylindei-  heads  and  barrels,  ciankshafl 
ci'ankcases,  propeller  shafts,  reduction  gear  co 
ers,  and  to  do  heat  treatment.  Figure  1  is  a  la 
out  sheet  showing  space  utilization  and  numb 
of  machines  i)laiined  and  installed.  Photograp 
1-6  on  the  following  pages  present  various  vie'? 
of  the  machinery  and  interior.  The  jiositions  fro 


wlch  the  photographs  were  taken  are  indicated 
01  the  drawing. 

he  Benton  ])lant  was  inlciidcd  lo  iJi'oducc  ar 
iilating  rods,  master  rods,  gears,  jigs,  and  mis- 
:  I  neons  small  parts.   Fignre  2  is  the  space  and 
liz^ition  Inyont  of  the  Itcnten  jilitiit,  Jilso  show 
II I  lie  number  of  machines  planned  and  installed. 
'iliigra])lis   7-10   on   the  following   pages   show 
or  of  the  machinery.    The  photographer's  po- 
iii  in  each  case  is  shown  on  the  drawing. 
lu'  Knnnnia  plant,  above  ground,  was  the  site 
I  ill  assembly,  although  it  had  originally  been 
il  lued   that   assembly    would    be    done    under- 
mid.     The  Yuba  and   Tage   works   were  rela- 
]-]y  small  and  only  a  few  pieces  of  equipment 
1'  installed. 

total  of  1075  machine  tools  were  acquired 

1  the    various    works — 76.5    from    Musashi,    7G 

■  I   Omiya,   88  from   Yokkaichi,   and   146  from 

•iiibine  known  as  Nippon  Nainenki.    Of  these, 

jD,  604  were  installed. 

ilans  called  for  14  test  cells,  but  only  2  were 
coipleted.  They  were  above  ground,  .so  ventila- 
lai)n  was  not  a  problem. 

imployment  reached  a  maximum  early  in 
iijust,  1945.  The  total  for  all  the  works  was  as 
fo  iws : 


Direct  E 
Regular 
Soldier 
Student 

mployees : 
employees : 

2,497 

,     876 

300 

3.673 

Indirect 
Regular 

Soldier 

1,642 

Student 

387 

2,029 

Total 

.      5.702 

and  Omiya  plants,  were  crankshafts,  crankcases, 
reduction  gear  housings,  and  volute  casings. 

I'rodnction  of  other  parts  was  ])lanned  but  not 
accomplislied. 

The  plans  also  called  for  jn-oducf  ion  of  300 
engines  ])('!•  niontli.  Actually,  liolli  new  antl  re- 
jiaired  engines  turned  out  in  194.")  wore  as  fol- 
lows : 


June 

July 

August 

Total 

New  engines     

] 
18 

4 
25 

5 
12 

11 

Kepaired  enginea 

55 

66 

Repairs  were  made  on  engines  that  had  been 
improperly  assembled  by  unskilled  workers  at 
other  plants,  and  on  engines  that  had  been  dam- 
aged in  bombing  attacks  at  other  places. 

No  research  or  experimentation  was  carried  on 
at  this  plant. 

Effect  of  Attack 

There  were  no  direct  attacks  on  the  subject 
plant,  and  officials  felt  no  concern  over  the  pos- 
sibility of  raids.  That  part  of  the  underground 
works  with  the  shallowest  protection  from  above 
was  180  feet  below  ground. 

Area  attacks,  however,  had  an  adverse  effect 
on  production.  For  one  week  after  the  area  at- 
tack on  Utsunomiya  City,  worker  attendance  fell 
off  about  20  per  cent.  There  was  no  serious  ])ower 
interruption  resulting  fioin  area  attacks. 

Plant  officials  said  that  difficulty  in  obtaining 
parts,  due  to  attacks  on  other  plants  and  to  poor 
transportation,  caused  a  slowing-down  of  pro- 
duction schedules. 


liirteen  per  cent  of  the  regular  and   soldier 

saloyees  woi-ked   on   two   shifts   of  ten   hours 

1 1   and  the  remainder  worked  on  one  ten  hour 


'I  t. 


Pi'duction 

nly  part  of  the  engine  components  were  pro 
i«!d  at  this  plant.  These  included  crankshafts, 
CTfkcases,  reduction  gear  housings,  certain  rods 
an  gears,  cylinders,  cylinder  barrels  and  heads, 
vo^te  casings,  etc.  The  parts  produced  by  this 
Phit  for  other  plants,  including  the  Hamamatsu 


Operational  Difficulties 

The  plant  manager  complained  of  very  serious 
operational  difficulties  that  had  not  been  over- 
come: underground  areas  were  cold  and  damp, 
causing  extreme  discomfort  to  the  employees; 
the  atmosphere  was  foggy  from  the  dampness, 
making  visibility  very  poor;  all  machinery  was 
constantly  subject  to  corrosion  unless  the  greatest 
precautions  against  it  were  taken.  One  difficulty 
that  was  not  encountered  during  the  war  was 
cave  ins,  although  there  have  been  several  since 
the  war  ended. 


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3 

i 


Photo  No.  1.  Crankcase  shops,  Tomiira  plant  at  Oya  Works. 


Photo  No.  2.  Crankcase  shop,  Toniura  plant  at  Oya  Works. 

6 


Photo  No.  3.  Cylinder  head  shop,  Tomiira  plant  at  Oya  Works. 


Photo  No.  4.  Cylinder  assembly  shop,  Tomura  plant  at  Oya  Works. 

7 


Photo  No.  5.  Cylinder  barrel  shop,  Tomura  plant  at  Oya  Works. 


Photo  No.  6.  Heat  treatment  shop,  Tomura  plant  at  Oya  Works. 


Photo  No.  7.  Articulating  rod  shop,  Benten  plant  at  Oya  Works. 


Photo  No.  8.  Gear  shop,  Benten  plant  at  Oya  Works. 
9 


Photo  No.  9.  Entrance  to  Benten  plant  at  Oya  Works. 


Photo  No.  10.  Jin  and  tool  shop,  Benten  plant  at  Oya  Works. 

10 


3  troduction 


SHIROYAMA 


[u  December  1044,  tlie  Nakajima  Aiicraft  Co. 
nted  to  dispei-se  the  airframe  production  fa- 
ijities  of  its  Utsunomiya  plant,  but  the  Munitions 
[iiistry  refused  permission,  saying  it  was  not 
it  necessary.  Finally,  in  March  1945,  permis- 
sn  was  granted  and  dispersal  to  underground 
rerns  at  Sliiroyaimi  bei;an.  Tliis  plant  was  op 
ited  in  conjunction  with  the  Oya  plant,  pre- 
iisly  discussed. 

Planned  production  at  Shiroyama  was  three 
iij;  assemblies  and  three  fuselages  per  day  but 
the  end  of  the  war  only  four  of  each  had  been 
npleted.  Manufacturing  began  late  in  April 
I.").  The  machine  shop  started  first,  then  com- 
lent  manufacture,  and  in  July,  wing  and  fuse- 
I  e  assembly  began. 

S'early  all  assembly  facilities  were  to  be  dis- 
sed  from  Utsunomiya  to  Shiroyama,  but  some 
re  to  be  retained  at  Utsunomiya  because  the 
I  ice  at  Shiroyama  was  inadequate. 

ganization 

)f  a  planned  nineteen  units  in  the  works,  with 
(total  floor   area    of   ()4!),7()0   square   feet,   only 

ht  units  with  333,000  square  feet  of  floor  area 
me  completed.     Four  of  these    (38,900  square 

t)   were  used   as   warehouses  for  tubing,  ex- 

ded  parts,  duralumin  bais,  oil,  and  paints. 

fhe  largest  of  the  other  four  units  that  actually 
^  into  production  was  the  Otomeyama  plant 
(•4,500  square  feet)  where  sheet  metal  parts 
•Me  produced.     Photographs  11-14  show  the  en- 

nces  and  some  of  the  presses. 

jfhe  next  largest  was  the  Watanabeyama  plant 
(v500  square  feet)  housing  the  wing  and  fuse- 
ie  assembly  and   jigs   for  tail  parts.     Photo- 


graplis  1.")  l(i  show  jigs  and  some  of  Ihe  main  air- 
frame parts. 

Tlie  Kaneiriyama  plant  (86,000  square  feet) 
contained  machine  tools  and  electric  heat  treat- 
ment furnaces.  Some  space  was  used  as  a  ware- 
house.   See  photographs  17-20. 

The  Tochigiyama  unit,  devoted  to  wing  spar 
manufacture,  contained  only  14,100  square  feet, 
and  all  machinery  had  been  removed  at  the  time 
the  inspection  was  made. 

An  ovei'-all  layout  of  all  parts  of  the  Shiro- 
yama installations  is  shown  in  Figure  3.  The  po- 
sition of  the  photographer  in  taking  each  of  the 
photographs  on  the  preceding  pages  is  indicated 
on  the  drawing  l)y  numbers  t-orrcspondini;  with 
numbers  on  the  photographs. 

In  July  1945,  when  dispersal  was  still  going 
on  from  Utsunomiya  to  Shiroyama,  the  combined 
number  of  employees  was  21,117.  This  figure  in- 
cludes both  direct  and  indirect  employees;  no 
further  break-down  was  available. 

Production 

The  only  airplane  type  intended  for  production 
at  Shiroyama  was  the  Army  fighter  Frank  (Jap- 
anese Ki-84).  Nearly  all  sheet-metal  parts  and 
some  machined  parts  were  to  be  made  here.  Other 
machined  parts  came  from  the  Tochig  and  Ot- 
awara  plants  of  Xakajima  but  subcontractors 
suj^plied  50  percent  of  all  parts  other  than  sheet- 
metal  pai'ts. 

Actual  airframe  production  amounted  to  only 
four  wing  assemblies  and  four  fuselages  before 
the  end  of  the  war,  but  inasmuch  as  production 
was  just  getting  under  way,  those  figures  can 
scarcely  be  used  as  any  measure  of  capacity  for 
the  Oya  plant.  Three  wing  assemblies  and  three 
fuselages  per  day  was  the  goal  that  had  been 
planned. 


11 


Photo  No.  11.  Tunnel  entrances  (Otomeyama  plant),  Shiroyama. 


Photo  No.  12.  Tunnel  entrances  (Otomeyama  plant),  Shiroyama. 

12 


Photo  No.  13.  Sheet-metal  press  (Otomeyama  plant),  Shiroyama. 


Photo  No.  14.  Part  of  20-ton  press  (Otomeyama  plant),  Shiroyama. 

13 


Photo  No.  1'?.  Fuselage  assembly  shop  (Watanabe  plant),  Shiroyama. 


Photo  No.  16.  Horizontal  stabilizer  jigs  (Watanabe  plant),  Shiroyama. 

14 


Photo  No.  17.  Machine  tools  awaiting  installation  underground,  Kaiieiriyama  Works  at  Shiroyac 


Photo  No.  18.  Warehouse  and  stockroom,  Kaneiriyama  Works  at  Shiroyama. 

15 


Photo  No.  19.  Machine  shops  for  airframe  parts,  Kaneiriyama  plant  in  Shiroyama. 


Photo  No.  20.    Electric  heat  treatment  furnaces,  Kaneiriyama  plant  at  Shiroyama. 

16 


OYA     ENGINE    WORKS 


NO 

AREA-SQ.FT 

PLACE 

DESCRIPTION 

100 

102,000 

Otomeyama 

Sheet  metal  pai^i* 

103A 

4.600 

Tochiglyama 

Warahouae- Tubing  and  entruded  ^larla 

103B 

14.  ISO 

-oil  and  paint 

lO-V 

6.000 

-duralumin  bar 

105B 

I9.B00 

Not  complete-Sub-assemblj 

106 

€^850 

Tochiglyama 

107 

87.200 

Kane  Ir)  yam  a 

Maohine  shop  and  h«st  Ireattnant 

108 

20.200 

Tochigiyama 

Not  tompl«te-hMt  tr«atm«fit 

110 

ae.500 

Waranabeyama 

Sub-assombly -rtnng  and  fus«lage 

112 

21,200 

Maru3hoyafn« 

Not  complete -sub-asiftmbly-  cowlinj 

113 

99,000 



It4-A 

21.200 

tnarlyama 

■■        -ShMt  matal  parts.  vyarchou^« 

IK-B 

n.TOO 

115 -A 

28.300 

115-B 

Z6,fiOO             1 

118 

14.200 

Maruhachiyama 

Warehouse -oil 

119 

17.700 

Tochigijama 

5ub-assernbly-v<ing5p»r 

120 

30.100 

Tanjayam* 

Not  complete-aub^ksemblyviin^ 

123 

23,400             ' 

Total 

649.700 

U.S. STRATEGIC    BOMBING  SURyEY_ 

UNDERGROUND  PLANTS 
NAKAJIMA    AIRCRAFT     CO. 

FIGURE      i 

)um  o  .  41  irua  p.  le) 


ASAKAWA 


This  plant  was  a  dispersed  location  of  the 
(isaslii  Works  of  the  Makajiina  Aiiciaft  ("o.  and 
IS  located  in  Die  steep  hills  on  the  west  edye  of 
akawa  villafie  which  is  two  miles  west  of 
ichioji  in  Tokyo  prefecture. 

It  was  jilanned  that  tiiis  plant  would  liave 
3,000  square  feet  of  floor  space  and  l,l!0()  nia 
ine  tools  for  the  production  of  300  engines  per 
)ntli  and  tJiat  it  would  be  in  production  by  July 
15.  However,  at  the  end  of  the  war  in  August, 
ly  G  out  of  31  tunnels  were  completed,  with  an 
?a  of  IT)", 000  square  feet  excavated.  Thi-ee  hun 
i(i  tiiiity  machine  tools  were  in  place  and  liad 
m  producing  engine  parts  since  July.  Xinety- 
e  otiier  machine  tools  had  been  delivered  to  tlie 
e  but  not  installed. 

The  tunnels  were  laid  out  in  tliree  sections  in  a 
id  network  (Figure  4).  No  previous  tunnels  or 
nes  had  been  in  existence  here  so  that  the  entire 
eavation  was  new.  External  evidence  of  this 
mt  could  be  seen  in  the  piles  of  spoil  and  in  the 
w  uncamouflaged  surface  buildings  which  were 
?d  as  offices  and  storehouses. 
The  tunnels  were  approximately  15  feet  wide 
d  12  feet  high  and  varied  in  length  from  100 
■t  to  1,200  feet.  Because  the  rains  caused  tJie 
ifs  of  tlie  tunnels  to  collapse  in  at  least  six 
ices,  extensive  timber  shoring  had  l>een  set. 
The  Nakajima  Co.  expected  to  manufacture 
^ine  parts  in  tlie  underground  woiks,  with  final 
ienibly  to  be  carried  out  in  dispersed  surface 
ildings  farther  up  in  the  hills.  By  1.1  August 
t5  about  10  engines  liad  been  completed.  In 
dition  there  were  about  300  crankcase  castings 
)red  in  Tunnel  1,  great  stores  of  cylinder  heads 
Tunnel  3,  and  many  other  stocks  of  engine  parts 
machining.  There  were  IS  engines  in  process 
assembly  in  two  dispersed  small  hangar-type 
Hidings. 

For  the  conveyance  of  parts  inside  the  tunnels, 
'o  of  the  tunnels  had  narrow-gage  tracks  while 


^ 


a  third  had  a  roller  conveyoi-  the  length  of  the 
tunnel.  Only  h.ind  methods  were  available  in  the 
rest  of  the  plant. 

Most  of  tlie  usual  types  of  machine  tools  were 
installed;  engine  latiies,  turret  lathes,  drill 
presses,  shajiers,  phniers,  giinders,  etc.  Eighty 
percent  of  the  330  installed  machine  tools  were 
American  made,  with  such  familiar  company 
names  as  Brown  and  Shariie,  (Mnciunati,  Warner 
and  Swazey,  American  Machine  Tool,  Bullard, 
and  others  in  evidence. 

The  six  tunnels  in  o]ieration  were  used  for  ma- 
ciiining  the  following: 

Xo.  1.  Cylinder  heads. 

No.  2.  Cylinder  barrels. 

No.  3.  Crankshafts. 

No.  4.  Propeller  shafts. 

No.  5.  Proi)eller  shafts. 

No.  G.  Engine  accessories. 

The  chief  problems  of  operating  this  plant  were 
caused  by  wet  floors  and  moist  atmosphere.  The 
floors  in  all  tunnels  examined  (Nos.  1  through  6) 
were  wet  and  in  several  places  were  under  several 
inches  of  water.  This  caused  much  illness  among 
the  workers  and  serious  corrosion  of  tiie  machines. 
At  the  time  of  inspection  the  machines  weVe 
covered  with  a  layer  of  grease  and  waxed  paper  in 
an  effort  to  preserve  them.  Even  so,  many  of  them 
were  seriously  corroded.  Photographs  21-25  show 
machine  tools  and  parts  in  the  plant. 

The  manager  of  the  jilant  reported  that  a  short- 
age of  new  cylinders  made  it  necessary  to  employ 
used  cylinders  in  the  manufacture  of  engines.  This 
was  veritled  in  the  assembly  shop  where  the  stock 
of  used  cylinders  slightly  outnumbered  the  new 
cylinders. 

Asakawa  was  inspected  on  24  October  1945. 


714387—47—3 


17 


GENERAL  ARRANGEMENT  OF  ASAKAWA    (UNDERGROUND)  PLANT 


Corrected   to  13  JULY  645 


JfflSHU    HIGHWAY 


AREA   CHART 

COM^mON 
10  tiin  a«« 

^yssstr 

TOTAL 

A 

131,116 

57,178 

188.294 

80X 

B 

80,429 

29,837 

110,288 

eox 

C 

90.408 

10,483 

40.871 

6S« 

TOTAL 

241,953 

97.478 

339.431 

78X 

T<^'' 


Sf^ 


UNDERGROUND  FACTORY 


1^^;^  CONTOUR 
llllllllllllll  SURFACE  BUILDING 


LEGEND             1 

PARTS  MACHNED 

SHAFT  GEARS 

REPRODUCTION  GEAR 

PUMTIMrrOEAR 

CAM  BOSS 

SUPERCHARGER  6EAR 

2S 


^® 


NOTE:Sli*e1®of2  figure    4 


UNOERGROUNO  PLANT 

ASAKAWA 

aENERAL  AfOUNSEHENT 


UNDERGROUND  FACTORY 

CONTOUR 

SURFACE  BUILONG 

NOTE-.ShMt®of  2     RGURE  4 


us.  STRATEGIC  BOWBWC  SOHVFT 


UNDERGROUND    PLANT 

ASAKAWA 

GEICRAL  ARRANOEMENT 

IltSIT  O-  4t(rm«^  1*>M 


GOKAN 


The  (ioknii  ])lant  of  the  Nakajiiua  Aircraft  Co. 
■;ir  Nuuiata  in  (inimiia  jjrefectiire  was  inspected 
('ai)tain  Kicliarilson,  the  intelligeuce  officer 
tlic  oSTtli  Infantry  Regiment,  97th  Division. 
II'  lollowini;  data  were  obtained  from  liim: 
jSi.xteen  tnnnels,  each  about  600  feet  long,  had 
en  excavated  by  5G5  Cliinese  prisonei's  of  war 
10  were  housed  nearby  in  a  labor  camp.  Some 
0  machine  tools  had  been  installed  in  the  tun- 
Is  while  many  other  tools  were  stored  outside. 


awaiting  the  completion  of  new  areas.  In  parts 
of  the  plant,  there  were  double  rows  of  machine 
tools. 

The  floors  at  Gokan,  as  at  Asakawa,  were  gen- 
erally wet  and,  while  .some  of  the  machinery  was 
protected  with  grease  and  tarpaulins,  many  other 
machines  were  severely  rusted. 

A  .semiunderground  plant  was  l)eing  built  near- 
liy  to  assemble  the  airframe  parts  which  were  to 
be  machined  in  the  nndergi-ound  section. 


19 


Photo  No.  21.  Asakawa  underground  plant. 


20 


Photo  No.  22.  Asakawa  plant  cylinder  heads  awaiting  machining.    Note  roller 


conveyor. 


Photo  No.  23.  Asakawa  plant.   Cross-tunnel  used  for  storage  of  engine  parts. 

21 


nil 


*=;=* 


1^ 


^.  -■\ 


-C^V* 


pa 

1    '■'-r-r 

— '    ■    ■" 

% 

Bi 

1 

B  '^  v^ 

TWKl 

^ 

-.-*l 


Photo  No.  24.  Asakawa  underground  plant. 


Photo  No.  25.  Asakawa  underground  plant. 
11 


YOSHIMATSU 


One  III'  Ilic  iiKisI  ;iii\  Mined  |il;ni1s  seen  in  Japan 
ivas  till'  Voshinialsn  ent;iii('  (ilant  of  Nakajima 
ociitcd  iH'ar  .Malsiiyaiiia,  '■'<-  miles  noitlnvest  of 
Tokyo.  Tliis  jilant.  wliicii  was  (lis]KMsc(l  fi-om  the 
Omija  Works,  ^vas  SO  peicent  coniplele  and  -was 
in  ])rodii((ioii  from  lo  .huie  until  the  end  of  the 
win.  Altlionj^li  it  was  planned  to  make  eomplete 
iigines  a1  this  plant,  only  the  nnicliininy  of  parts 
ivas  actnally  earried  ont. 

The  Japanese  aircraft  indnstry  was  not  tlie  first 
irganization  to  i^o  nndeij^ronnd  at  ^Matsnyama. 
riiat  distinction  jioes  to  a  jironp  of  cave  dwellers 
)f  abont  1, .")()()  years  ajio.  More  than  100  caves 
pockmark  tlie  face  of  the  cliff  in  which  the  air- 
raft  tnunels  aie  located.  Each  of  these  caves  has 
in  entrance  aliont  4  to  5  feet  square  which  opens 
into  a  heniisjdierical  room  abont  8  to  10  feet  in 
iiameter  ( l'lioto};iaphs  20  and  27).  These  caves 
ivere  the  dwellintis  of  some  ancient  tribe. 

Farther  alony  tlie  clitT  is  anotlier  cnriosity — the 
Madman's  Hotel,  which  is  an  underground  house 
tarted  by  Ninekichi  Takaliashi  in  Nishi-Yoshimi- 
inura.  Tlie  house  was  begun  in  the  thirty-seventli 
rear  of  the  reign  of  Meiji  (1904)  as  a  financial 
reuture.  He  expected  that  it  would  take  three 
enerations  to  complete  but  by  that  time  it  would 
36  such  a  curiosity  that  visitors  would  pay  to  see 
<uch  a  place  and  the  Takaliashi  family  would 
'ventnally  become  financially  independent. 

He  worked  for  I'O  years  on  the  project  and  had 
2  large  rooms,  1  small  room,  numerous  corridors, 
ind  the  staircase  to  the  second  floor  already 
ai'ved.  The  entrance  was  flanked  by  2  Grecian 
olnmiis  carved  into  the  cliff  si<le  and  led  into  the 
lobby,  a  room  about  10  feet  by  20  feet  with  the 
staircase  in  the  rear  center.  The  living  room, 
i  by  12  feet  had  stone  tables,  chairs,  and  fixtures. 
The  dreams  of  Takahashi  were  not  realized  as  his 
5on  abandoned  what  he  considered  to  lie  a  mad- 
man's project  when  the  father  died. 

Both  of  these  projects  served  a  useful  purpose 
for  the  Japanese  in  104.").  as  they  inspired  the 
onstruction  of  an  underground  aircraft  plant  in 
this  hill  of  sedimentary  volcanic  ash. 

On  15  January  ]()4.">,  this  factory  received 
orders  to  go  underground  and  excavation  was 
started   shortlv    thereafter.      As    sections    of   the 


tunnel  areas  were  comiileled,  maciiine  tools  were 
installed  and  the  machining  of  aircraft  engine 
parts  was  begun.  The  first  actual  work  was  done 
on  1.")  June  and  continued  nnfil  the  end  of  the 
war. 

Tlie  total  planned  area  of  this  plant  was  353,000 
square  feet,  to  be  spread  over  six  areas  (Figure 
5 1 .  The  first  five  areas  were  completely  excavated 
and  tliree  tunnels  of  the  sixth  area  were  com- 
pleted, making  a  total  excavated  area  of  about 
320,000  square  feet.  The  total  length  of  tunnel 
amounted  1o  approximately  33,000  feet. 

Each  tunnel  was  13  feet  wide  and  varied  in 
height  from  11  feet  to  13  feet  to  accommodate  the 
use  to  which  the  tunnel  was  put.  (Photographs 
28-36). 

The  tunnels  were  fairly  dry  due  to  the  peculiar 
desiccating  quality  of  the  volcanic-type  rock 
through  which  they-  were  carved.  The  tempera- 
ture remained  fairly  constant  underground 
throughout  tlie  year.  Area  No.  5  was  shored  up 
by  timbers  but  most  of  the  remainder  needed  no 
siqiport.  In  many  places  concrete  floors  had  been 
laid. 

Four  hundred  fifty  machine  tools  had  been 
brought  to  the  site  but  only  300  had  been  installed 
in  the  tunnels.  Machines  were  set  in  the  tunnels 
ill  single  rows. 

Corrosion  of  equijunent  became  a  problem 
almost  at  once.  To  combat  this  condition  it  was 
made  the  responsibility  of  each  workman  to  keep 
his  machine  from  rusting.  To  prevent  corrosion, 
finished  parts  were  removed  from  the  tunnels  im- 
mediately upon  their  completion. 

Plans  called  for  the  manufacture  of  300  engines 
per  month  in  the  underground  plant,  with  final 
assembly  in  dispersed  buildings  in  and  near 
Matsuyania.  Actual  production,  however,  con- 
sisted only  of  master  rods,  cylinder  heads,  cylinder 
barrels,  and  crankshaft  counteilialances.  Between 
200  and  300  of  each  of  the  above  parts  were  com- 
pleted by  15  August. 

Evidence  of  this  work  was  seen  in  the  piles  of 
master  rods,  counterbalances,  and  cylinders  that 
were  stacked  lieside  the  machine  tools  and  in  stor- 
age tunnels. 


23 


Eventnjtl  employnieiil  lieie  would  have  been 
J;,000.  Uowever.  ouly  -"iOd  weie  iKtiially  at  work 
undei-ground  in  Aiijiiist.  K.  Hiruta  was  plant 
manager. 

Transportation  of  parts  to  and  from  the  plant 
was  by  truck. 

Several  tnnisiial  featines  were  noted  in  this 
plant : 

1.  In  area  No.  i.  nine  heat  treatment  pits  were 
being  dug  in  the  tunnel  floor.  Each  pit 
measured  S  feet  wide,  t!  feet  deep,  and  lo 
feet  long. 

2.  Tall  machines  Avere  coiiiUersunk  into  the 
floor  of  the  tunnel  so  tliat   the  largest  ma- 


chines seen  anywhere  underground  were  i 

place  here. 
.">.    A    power    substation    of    three    2o0-kv.=  i. 

transformers  was  built  for  each  of  the    e 

completed  areas. 
4.    Tunnel  cross  sections  varied  to  suit  the  m\ 

The  entrances  to  Sections  1  and  6  were  iu  sh  i 
cliffs  at  least  75  feet  high.    The  whole  establ 
ment   was   well   concealed   except  for  a   built 
area  of  5  surface  buildings    (warehouses,  offn 
etc.)  near  the  entrances  to  Number  4  area. 

Yoshiinntsu  was  inspected  on  13  and  15  Novi 
ber  1!)45. 


I 


24 


I 


^-  ^K^^'^-.Ji-^ti. 


m^ 


^5^-^ 


Photo  No.  26.  Ancient  caves  at  Yoshimatsu. 


Photo  No.  27-  Close-up  of  ancient  caves  at  Yoshimatsu. 

25 


Photo  No.  28.  Entrance  to  Nakajinia  tunnels  at  base  of  cliff,  Yoshimatsu. 


I'hoto  No.  29.  Entrances  to  tunnels,  Yoshimatsu. 


26 


Photo  No.  iO.  Machine  tool  in  process  of  installation,  Yoshimatsu. 


Photo  No.  31.  Tunnels  at  Yoshimatsu. 

27 


Photo  No.  32.  Machine  tool  in  process  of  installation,  Yoshitnatsu. 


Photo  No.  33.  Machine  tools  in  position,  Yoshitnatsu. 


28 


w^ 

Mj 

HHHH 

w    ^ 

^3 

"1 

••  f  ^^H 

■ 

«l 

^^^^^9 

I 

^^^^H|^jp^[^^e7<%.s^  ■>"■'— -~ 

Photo  No.  34.  Machine  tools  standing  in  water.  Landslide  had  formed  a  dam  near  entrance^ 


Photo  No.  35.  Three  250-kv.-a.  transformers,  Yoshimatsu. 
*'  29 


Photo  No.  36.  Heat  treatment  pits  under  construction,  Yoshimatsu. 


30 


YABUTSUKA 


The  Yabiilsuka  aiifiiuue  plant,  located  6  miles 
(ulliwest  of  Ota,  Gumma  prefecture,  was  a  ilis- 
ersed  location  of  the  Ota  "Works  of  the  Nakajima 
ircraft  Co. 

Tt  was  not  possible  to  inspect  the  tunnels  of 
lis  ]ilant  on  the  date  of  visit,  13  November  1945, 
pcause  all  entrances  had  caved  in.  The  local 
'i|ianese  attributed  the  collapse  to  the  torrential 
( lober  lains  and  denied  that  any  explosion  had 
;ilcd  them.    At  several  entrances  it  was  possible 

liiok  over  the  landslide  into  the  tunnels  where 

rcmld  be  seen  that  water  was  standinj;  from  1 
feet  deep. 


Thirty  tunnels,  each  13  feet  wide  and  11  feet 
hifih,  were  completely  excavated  and  shored  up 
with  timbers.  This  represented  one-half  of  the 
|)rojected  ai'ea. 

Excavation  was  started  in  January  1945  by 
1,500  men  working  on  a  10-hour  shift.  Planned 
lay-out  is  shown  in  Figure  6. 

No  machine  tools  were  installed  or  even  brought 
to  the  site. 

This  plant  was  almost  inaccessible.  Only  one 
very  narrow  road  which  would  barely  permit  pas- 
sage of  a  jeep  led  to  the  site  of  the  plant. 


YUSENJI 


\  usenji,  1  miles  west  of  Komatsu  in  Ishikewa 
efecture  on  the  northwest  coast  of  Japan,  was 
dispersed  airframe  plant  of  the  Handa  Works 
the  Nakajima  Aircraft  Co. 

The  underground  areas  of  tliis  plant  were  the 
riad  and  irregular  caverns  of  ancient  firebrick 
id  modern  stone  quarries.  In  prewar  years  many 
the  modern  buildings  of  Tokyo  and  Osaka  had 
in  constructed  fi'om  building  stone  dug  out  of 
site. 

>f  a  planned  area  of  211,000  square  feet,  about 
"000  scjuare  feet  were  ready  for  use,  while  100 
400  machine  tools  planned  were  in  operation. 
The  jilant  was  designed  to  produce  small  air- 
Ibme  parts,  metal  fittings,  and  similar  items  for 
e  C-6  scouting  plane.  Production  on  a  small 
ale  began  late  in  June  1945  but  only  a  few  parts 
?re  completed  by  the  end  of  hostilities.  The  con- 
rsion  of  the  caverns  for  aircraft  production  be- 
iin  in  February  1945  under  Navy  supervision  and 
jnipletion  was  set  for  the  end  of  September,  but 
ily  30  percent  progress  had  been  made  by  15 
iigust. 


An  extensive  network  of  tunnels  and  quarries  is 
hidden  under  the  hills  witii  only  a  few  entrances 
and  some  new  spoil  to  reveal  their  existence  to  the 
photo  interpreter.  Small  entrance  tunnels  about 
9  feet  wide  and  6  feet  high  with  extensive  and 
heavy  shoring  led  into  the  main  galleries  which 
were  of  irregular  shape  (Fig.  7). 

Concrete  bases  had  been  laid  on  which  to  mount 
the  machine  tools  and  the  cavern  floors  were  dry. 

Yusenji  was  easily  accessible  by  highway  and 
electric  raili'oad  from  Komatsu.  The  actual  tun- 
nel level  is  only  a  few  feet  above  sea  level.     . 

Of  all  the  underground  factories  seen,  this  one 
seemed  among  the  best  from  the  standpoint  of 
transportation,  concealment,  and  working  condi- 
tions. 

One  half  mile  north  of  the  Nakajima  site  was 
another  hill  with  a  similar  network  of  caverns, 
which  housed  great  stores  of  munitions  that  were 
being  removed  by  United  States  troops  on  20 
November  1945,  the  date  of  inspection. 


31 


LAYOUT  OF  YABUTSUKA  PLANT 


U.S.  STRATEGIC  BOMBING  SURVEY 


UNDERGROUND  PLANT 
YABUTSUKA 

FlCjUfiE     6 


THin  O  -  41  IFiCB  (I   IJI  ^ 


o 


.^.U 


5   ENTRANCE 


YUSENJI   UNDERGROUND  PLANT 

OF 

NAKAJIMA  CO. 


HEIGHT  VARIES  FROM    5i  FT   TO  16  FT 

[  SLANTED  LI^CSAfiE•4  TUNNEL  GROUP 
MACMNE  TOOLS  KSTALLEDJ 


i^*3  ENTRANCE 


USSTRATEGC  BOMBING  SURVEY 


YUSENJ  UNDETfGROU\D  PLANT 

(OSPEHSED  FROM  HANQA  VKJfilS  OF 
NAKAJIMA-)  F)&-r 


T10*T  O  -  «T  iru>  K   HI  Ho.    1 


PART  II 

UNDERGROUND  PLANTS  OF 
MITSUBISHI  AIRCRAFT  CO. 

KATSURA 


The  Katsuia  plant  of  Mitsubishi  No.  8  Engine 
Woiks  was  located  at  Mameda,  one-quarter  mile 
north  of  Katsuia  station,  southwest  of  the  city  of 
Kyoto.  Not  strictly  an  underground  plant,  it  was 
au  interesting  use  of  a  lailroad  viaduct  lo  con- 
ceal and  protect  a  shop. 

The  space  under  the  viaduct  where  it  crossed  a 
liighway  was  enclosed  by  the  erection  of  mud  walls 
along  the  steel  and  concrete  trestles.  The  area 
thus  enclosed  amounted  to  25,000  square  feet. 


Seventy  two  machine  tools  had  been  installed 
and  were  in  operation  from  June  194.1.  The  entire 
plant  was  used  for  the  machining  of  all  master 
rods  for  Kasei  25  engines. 

It  was  evident  that  the  plant  had  been  an  effi- 
cient one.  It  was  clean,  well-lighted,  and  dry, 
with   an  orderly  arrangement   of   machine   tools.' 

In  external  appearance  there  was  no  evidence 
to  reveal  the  location  of  this  plant  to  the  photo 
interpreter. 

The  jilant  was  inspected  on  :'.()  October  194.1. 


OTANI 


The  Otani  plant  was  a  dispersal  location  of  the 
Mitsubishi  No.  S  and  No.  14  Engine  Works  and 
wa.s  situated  at  Otani,  1  mile  southwest  of  Otsu, 
a  city  6  miles  east  of  Kyoto. 

Two  abandoned  railroad  tunnels,  2,1(50  and 
2,1'OU  feet  long  respectively,  were  used  as  gear- 
tutting  and  grinding  shops  for  the  aforementioned 
Iilants.  Thirty-six  different  kinds  of  gears  were 
machined  here  on  2S6  machine  tools  belonging  to 
^'o.  8  Works  and  2.5  tools  belonging  to  No  14 
Works. 

Installation  of  machine  tools  began  16  JIarch 
1945  and  was  completed  in  April.  Full  produc 
tion  was  carried  out  for  about  2i/o  months. 

A  total  of  700  persons   was   employed    in   the 


plant.  Many  of  the  employees  were  girl  students 
who  "worked  very  hard  but  not  too  well.".  More 
than  half  of  the  machine  shop  employees  were 
students. 

The  tunnels  were  reasonably  dry  but  the  man- 
:iger  leported  that  there  was  always  trouble  with 
moisture,  which  caused  worker  illness  and  cor- 
rosion of  machines  and  tools. 

Six  wooden  buildings  were  erected  in  the  valley 
at  the  southwest  end  of  the  tunnels.  The.se  build- 
ings were  to  be  used  for  heat  treatment,  carboni- 
zation, and  copper  plating  but  were  not  completed 
by  the  war's  end.  They  were  not  camouflaged  nor 
was  it  intended  to  do  so. 

The  plant  was  inspected  on  31  October  1945. 


KIYOTAKI 


Kiyotaki  was  a  dispersal  of  Mitsubi-shi  No.  14 
lMij,'ine  \'\'(irks  and  was  located  in  two  abandoned 
**'ieetcar  tunnels  5  miles  west  of  Kyoto. 

The  plant  was  very  similar  to  Otani  and  came 
into  production  in  May  1945,  just  ten  days  after 

714387—47—4 


Otani.      The   tunnels    were    1,970    feet    long    and 
housed  120  machine  tools. 

Machining  of  exhaust  valves  was  the  only  opera- 
tion to  take  place  here. 


33 


KUKURI 


The  Kukuri  plant  of  the  Mitsubishi  No.  4 
Engine  Works  was  located  in  the  hills  three  miles 
southeast  of  lliromi,  about  20  miles  northeast  of 
Nagoya  (Fig.  8). 

An  elaborate  netwoi-k  of  38  tunnels  totaling 
23.000  feet  in  length  was  excavated  in  a  ridge  of 
sedimentary-type  rock.  The  total  planned  area 
was  360,000  square  feet,  of  which  270.000  square 
feet  were  completed.  In  cross  section  the  tunnels 
measured  16  feet  wide  and  11.5  feet  high  (Figs. 
9  and  10). 

During  construction  the  tunnels  were  cut  en- 
tirely through  the  hill  so  that  the  machine  tools 
could  be  handled  directly  into  each  tunnel.  After 
the  machines  were  in  place  it  was  intended  to  close 


and  conceal  the  entrances  to  all  but  three  tunnels 
wliich  would  then  become  the  only  entrances. 

One  hundred  sixty-four  of  a  planned  800  ma 
chine  tools  were  installed  underground.  Thesi 
machines  were  lined  along  both  sides  of  the  tun 
nels,  leaving  an  aisle  about  four  feet  wide  in  th' 
center. 

This  plant  was  supposed  to  manufacture  engine 
liut  no  actual  production  was  achieved. 

These  tunnels  were  among  the  better  ones  see 
in  Japan.  They  were  very  dry,  well  laid  ou' 
had  smooth  floors,  and  seemed  roomier  than  mam 
others  (Photographs  37-40). 

Kukuri  was  inspected  on  3  November  1945. 


I 


34 


> 

=  OT 

> 

^  ^ 

3 

S?i     - 

e 

<  9     ^ 

X  Q     O 

^ 

Z     b. 

o 

_  o 

(T  cr 

3  UJ 

i 

^  o 

f 

3  2 

n 

>e  3 

7 

35 


UNDERGROUND    PLAI 

li...«|   PILOT    TUNNELS 

^^    ENLARGING   UNDER   CONSTRUCTION' 

^^    ENLARGING    FINISHED 

IQO 200 MO 


U.S.  STRATEGIC  BOMBlNG  SURVEY 


KUKURI  UNDERGROUND  WORKS 
AUG.  IS,  IMS 


Turn  0-  «T(rK»p.  Ml* 


TltSRT  O  -  41  (Pi»  p.  SB)  No.  1 


\ 


3 
3 


0 
JS 

01 

u 

a 

X 

<j 

a 


6 
Z 
o 
o 

j3 


37 


"fli 

I 
1 

l^^gj 

:  f 

k 

-,• 

fe 

^ 

'^•- 


-em 


,r«-fc 


c 


in'         '^ 


^ 


■  i   .' 


a 

75 


3 

6 
Z 


o 


a 


38 


Photo  No.  39.  Kukuri  plant.  Two  long  rows  of  machine  tools 


Photo  No.  40.  Kukuri  plant.   Machine  tools  being  installed. 

39 


NIKODA 


The  Xikoda  undergroimd  plant  of  the  Mitsubishi 
No.  ")  Airframe  Works  was  situated  in  the  hills  6 
miles  west  of  the  city  of  Ueda  in  Nagano  prefec- 
ture. 

Orders  for  dispersal  into  the  Ueda  area  were 
received  by  Mitsubishi  from  the  Army  in  April 
1945.  The  actual  excavation  of  the  underground 
plant  was  supervised  by  the  Army.  The  techni- 
cians in  charge  came  to  Nikoda  after  completion 
of  the  Central  Army  Underground  Headquarters 
at  Matsushiro.  between  Nagano  and  Ueda.  Three 
areas  were  planned  with  17,  6,  and  15  tunnels, 
)-espectively.  Each  tunnel  was  to  be  13  feet  wide 
and  10  feet  high  and  shored  witli  timber  to  prevent 
roof  collapse. 

Tlie  production  goal  was  an  output  of  50  Ki-83 
aircraft  per  month  in  conjunction  with  a  nearby 
semiunderground  plant.    However,  no  production 


was  realized  and  no  machine  tools  were  install 
At  the  war's  end  the  underground  plant  wa.s 
per  cent  complete,  the  power  installations  were 
per  cent  complete,  and  the  semiunderground  pli 
was  45  per  cent  complete,  with  33  buildii 
erected. 

The  schedule  called  for  total  completion  of 
underground  plant  in  September  1945. 

At  the  time  of  inspection  the  tunnels  were  ■> 
and  damp.  When  asked  what  precautions  agai 
worker  illness  and  machine  corrosion  had  b 
taken,  the  plant  manager  replied  that  there  \ 
no  time  to  study  any  problem  other  than  that 
getting  the  machines  underground. 

Transportation   of  material   to   and   from 
plant  was  expected  to  be  by  truck  only. 

Tlie  inteiviews  and  inspection  were  conduc 
on  IL'  November  1945. 


MATSUMOTO 


The  -Mitsubishi  No.  1  Airframe  Works  had  a 
combined  underground  and  semiunderground 
I)lant  under  construction  several  miles  southeast 
of  Matsumoto  in  Nagano  prefecture. 

This  plant  was  designed  to  produce  20  experi- 
mental aircraft  per  month.  The  planned  area  was 
25:i,000  square  feet,  all  of  which  was  excavated, 
but  only  40  percent  of  it  was  ready  to  receive  ma- 
chine tools.  No  machine  tools  had  been  installed, 
however,  and  there  was  no  production. 

Plans  were  made  in  February  1945  to  go  under- 
ground at  this  location  and  work  liegan  on  the 
tunnels  in  April  under  the  supervision  of  the 
Army.  Although  the  original  survey  conducted 
by  the  Army  concluded  that  no  shoring  would  be 
needed,  the  rock  proved  unsafe  and  extensive  shor- 
ing with  timber  became  necessary.  It  was  planned 
to  use  concrete  to  support  the  weak  spots  in  the 
tunnels  but  a  shortage  of  cement  prevented  this. 
In  fact,  timber  also  became  scarce  very  soon,  when 
three  times  as  much  timber  as  calculated  was 
needed. 

An  insufficient  number  of  mining  engineers 
added  to  construction  problems. 

Transportation,  however,  proved  to  be  the  chief 
problem  in  going  underground,  first,  in  the  move- 
ment   of    machine    tools    and    equipment    from 


Nagoya  to  Matsumoto  and  later,  to  transport : 
terials  to  the  underground  site.    Transport  to 
underground  plant  from  Matsumoto  was  by  tri 
over  narrow  and  poorly  maintained  roads. 

The  schedule  called  for  50  percent  complet 
and  the  beginning  of  production  in  June  1945  i 
for  total  completion  in  August.  Due  to  the  d 
culties  already  enumerated,  only  40  percent  o 
pletion  was  reached  in  August. 

The  familiar  comment  was  again  stated  he 
the  great  haste  of  dispersal  left  only  time  to  c 
sider  tlie  basic  problem  of  getting  the  mach 
tools  underground  and  out  of  reach  of  the  An 
ican  bombers.  Such  serious  considerations 
protection  of  machinery  against  corrosion,  vei 
lation,  and  worker  health  were  postponed.  Even 
ally,  Mitsubishi  hoped  to  solve  these  problems 
lieat  and  ventilation. 

I'arts  fabrication  for  Ki-83,  Ki-67,  Keppn,  a 
Taiyo  was  to  take  place  underground.  Fii 
assembly  was  to  be  accomplished  in  the  150  sei 
underground  buildings  in  the  surrounding  hi 
Testing  was  to  be  done  in  semiunderground  bui 
ings  at  nearby  Murai  airfield. 

The  date  of  inspection  of  Matsumoto  was 
November  1945. 


IfD 


11( 


40 


OGAMI 


Jhe  Ogami  imdergiound  plaut  of  Mitsubishi  No. 
Airframe  Works  was  located  10  miles  south  of 
ibka  in  Toyama  prefecture.  A  semiunder- 
luud  plant  at  Haiinyamura  was  operated  in 
se  conjunction  with  Ogami. 

I'his  plant  was  still  under  construction  by  the 
ernment  and  had  not  yet  been  taken  over  by 
subishi.    The  excavation  was  30  percent  com- 


plete Init  progress  toward  actual  production  was 
only  10  percent  advanced. 

Tunnel  cross  sections  measured  13  feet  by  10 
feet  after  shoring  had  been  erected.  The  maxi- 
mum tunnel  length  was  1,150  feet.  No  machine 
tools  liad  been  installed. 

Ogami  was  inspected  on  18  November  1945. 


NUKATANI 


'lie  Nukatani  underground  plant  of  Mitsubishi 
12  Engine  Works,  four  miles  south  of  Kana- 
•a,  was  one  of  the  most  unusual  plants  to  be 
ted. 

"he  necessity  for  performing  a  certain  amount 
mountain  climbing  to  an  altitude  of  750  feet 
t  a  strange  air  to  the  Nukatani  underground 
ut.  The  plant  was  accessible  only  on  foot  up 
larrow,  recently  constructed  road  which  was 
ihed  out  in  many  places  by  the  heavy  October 

IS. 

Lucient  caverns,  from  which  the  people  of  a 
t  age  extracted  tire  brick,  were  at  first  intended 
the  Japanese  Navy  to  be  used  as  a  Naval 
anal.  Early  in  April  1945,  the  Navy  started 
■k  on  making  the  tunnels  and  caverns  usable 
late  in  the  same  mouth  abandoned  the  project 
turned  it  over  to  Mitsubishi  for  aircraft- 
ine  production. 

litsubishi  subcontracted  the  construction  of 
plant  and  the  company  was  to  be  reimbursed 
r  by  the  government.  Because  of  the  inacces- 
lity  of  the  site,  it  became  necessary  to  initiate 
rge  civil  road  building  project  to  the  plant,  a 
dential  building  program,  and  a  bridge  con- 
ctiou  program  to  span  the  steep  chasms  to  the 
t. 

itsubishi  did  not  approve  of  Nukatani  but  was 
er  constant  pressure  from  the  government  to 
d  a  plant  at  this  location.  The  company's 
obction  was  based  ou  the  knowledge  that,  in 
K  itioii  to  being  inaccessible,  the  plant  also 
*''ild  probably  be  out  of  production  for  four 
Ti'itlis  each  year  because  of  the  heavy  snows  in 
liwest    Honshu    duiing    the    winter    months. 


Furtheimore,  the  problem  of  transportation  of 
both  workmen  and  products  presented  even  more 
serious  problems  than  those  which  already  had 
caused  great  difficulty  in  other  more  desirable 
locations. 

Despite  these  considerations,  the  plant  was  con- 
structed to  house  one  of  their  more  important 
works  to  produce  exhaust  turbines  and  fuel  injec- 
tion pumps.  Beginning  10  July  1945,  machine 
tools  were  laboriously  pulled  up  the  mountain 
road  by  hand  and  roller  means  and  by  the  end  of 
the  war  146  machine  tools  were  in  place.  In 
addition,  253  tools  were  stored  at  the  base  of  the 
hill  in  shrines  and  schoolyards.  Almost  all  of  the 
machine  tools  were  of  American  make,  because 
of  the  high  degree  of  accuracy  required  in  making 
these  parts. 

Actual  production  had  not  yet  begun  but  was 
anticipated  within  a  short  time. 

The  caverns  and  tunnels  were  very  dry  and  in 
many  places  concrete  floors  were  laid.  It  was  not 
necessary  to  shore  up  the  caverns  as  natural  pil- 
lars and  the  strength  of  the  rock  itself  were 
sufficient  support. 

Located  on  many  levels  throughout  the  moiin- 
tain,  the  tunnels  ranged  in  elevation  from  650  to 
800  feet  above  sea  level.  The  average  cavern  was 
20  feet  wide  while  the  height  varied  from  12  to  20 
feet   (Fig.  11). 

During  the  early  summer  of  1945  the  Japanese 
Navy  made  aerial  reconnaissance  of  the  area  and 
reported  that  the  new  road  revealed  the  location 
of  the  jjlant. 

Nukatani  was  visited  on  19  November  1945. 


41 


SHAKUTANI 


Shakiitiiiii,  located  one  mile  west  of  Fukui  city 
ill  Fnkiii  prefecture,  was  an  underground  disper- 
sal of  Mitsubishi  No.  IS  Engine  Works. 

This  plant  was  an  elaborate  arrangement  of 
caverns  and  tunnels  consisting  of  four  completed 
underground  areas  as  well  as  a  semiundergrouud 
plant  (Fig.  12).  So  skillfully  were  the  semiunder- 
grouud plants  built  into  the  hillside  that  one 
building  was  almost  passed  during  an  inspection 
trip  before  it  was  noticed. 

Caverns  from  which  Shakutani  stone — a  famous 
Japanese  building  stone — had  been  removed,  fur- 
nished the  s])acc  for  this  plant.  Work  was  started 
in  February  Iflio  to  ready  the  caverns  for  use  by 
the  Mitsubishi  Co.  and  the  movement  of  machinery 
into  the  plant  began  in  April. 

The  machine  tools,  of  which  !'!)(!  had  been  in- 
stalled, were  only  in  the  process  of  alignment  and 
testing,  and  it  was  claimed  liy  the  company  that 
no  production  was  achieved. 


This  plant  was  well  advanced   (considered 
percent  complete  by  the  Mitsubishi  Co.)   by  t 
average  standard  of  underground  plants.    In  adi 
tion,  it  was  near  the  local  ground  level  and  w 
easily  accessible  by  highway. 

The  caverns  and  tunnels  were  very  dry,  nev; 
theless,  most  of  the  machine  tools  were  corrodt 
The  caverns  followed  the  seam  of  building  sto 
and  were  therefore  of  varied  size,  on  many  diff( 
ent  levels,  and  of  generally  high  ceilings  (12  to 
feet).  Only  one  landslide  occurred  during  t 
October  rains. 

The  machine  tools  for  one  area  were  lower 
into  the  tunnels  through  a  vertical  shaft  60  fi 
long. 

This  jjlant  was  to  produce  gears  and  light  mei 
parts  for  engines. 

The  date  of  inspection  was  21  November  19 


SABAE 


Stone  ((uariies  :?()()  feet  above  ground  level  pro- 
vided the  setting  for  the  Shinyokoe  plant  of  the 
.Mitsubishi  No.  18  Engine  Works  at  Sabae  in 
Fukui   iirefeclure. 

This  plant  consisted  of  two  sections,  the  first 
being  in  the  stone  (juarries  well  up  into  the  hill, 
the  second  ((insisting  of  a  grid  of  newly  excavated 
tunnels  at  ground  level  at  the  base  of  the  hill. 

The  (piarry  section  was  a  series  of  caverns  with 
large  rooms  and  lofty  ceilings.  One  room  was 
fully  7.">  feet  long.  2.")  feet  wide,  and  IS  feet  high. 
Concrete  floors  had  been  laid  in  many  places  and 
throughout  the  tunnels  it  was  exceptionally  dry. 

As  may  be  seen  from  the  attached  drawings, 
(Figs.  13A  and  13Bj  the  caverns  are  not  syste- 
matic but  wind  about  in  eccentric  patterns  and 
are  on  many  levels.  At  one  place  a  broad  flight  of 
stone  stairs  elicited  the  comment  "It's  just  like  a 
cathedi'al  underground." 

This  upjier  section  of  tlie  jjlant  had  been  wired 
for  electric  jiower.  Two  200-kv=a.  transformers 
and  a  switchboard  had  been  installed. 

Twenty  six  machine  tools  were  in  position  in 
lireparation  for  the  jiroduction  of  cylinder  heads. 
A  large  stock  of  iiimiachined  cylinder  heads  was 
on  hand  Imi   it   was  maintained  liy  company  offi- 


cials that  no  productive  work  had  emanated  frc 
this  plant  by  15  August  1945. 

The  newly  excavated  tunnels  near  the  base 
the  hill  were  among  the  best  of  this  type  that  we 
seen  (Fig.  14).  The  rock  was  dry  and  solid  ai 
no  supporting  timbers  were  needed  to  reinfoi 
the  roof.  Some  extremely  roomy  tunnels  ( 
undergiound  standards)  were  inspected.  Sever 
tunnels  were  20  feet  by  10  feet  in  cross  sectic 
dimensions.  A  total  of  13  tunnels,  each  about  3 
feet  long,  had  been  completed  but  no  machine  too 
were  installed. 

The  entire  lay-out  of  this  plant  was  excellent 
concealed  from  the  standpoint  of  aerial  reconnai 
sauce.  Only  a  very  small  amount  of  spoil  wi 
visible  and  the  roads  were  almost  completely  coi 
cealed  by  trees.  The  plant  was  accessible  t 
Sal)ae  by  an  existing  road. 

The  impression  gained  was  that  this  plai 
would  have  become  a  good  ]iroducer  of  engin 
parts  within  two  months  and  that  it  would  hav 
been  comparatively  safe  from  direct  bombin 
attack. 

The  Sabae  area  was  inspected  on  21  Novembe 
1945. 


42 


UNDERGROUND     FACTORY    MITSUBISHI    CO. 


[:;:|:;:j  COMPLETED 

I       jiN  pfiocess 

PLANNED 


NOTE     9  HOLES- TOTAL   FLOOR    AREA"   IC^eOOSO.FT 
(NO  20  TO  29    HOLES-   146  MACHINE    TOOLS) 
TOTAL    AREA  -  395^00  SO.  FT 
ELEVATION      IN    FEET 


US.  STRATEGIC    BOMB   SURVEY 


UNDERGROUND    PLANTS 
NUKATANI 


LAYOUT     OF     SHAKUTANI      PLANT 


UNDERGROUND 


NO  Of  HOLE 

AREA 

OOfMACWC  IDOLS, 

1 

34^32 

31 

2 

34^62 

35 

3 

wee 

IS 

4 

4M20 

217 

TOTAL 

I23k094 

296 

SEMI-UNDERGROUND 


NO 

WIOTH- LENGTH 

AREA 

USED  FOR 

Wi 

2297    X  6560 

1506.83 

OFFICE 

V* 

4694    X   32.80 

1506.83 

offk;e 

»4 

45-94   X  65,60 

3013  66 

WAREHOUSE 

w. 

32.80  X  45,94 

1506  83 

- 

w. 

2297  X  65,60 

1506.83 

■ 

V* 

32.60   X   4594 

1506.83 

OMNG  HALL 

*7 

45,94    X   65,60 

300  66 

WAREHOUSE 

*? 

4594    X   65,60 

30S.66 

■ 

•* 

4594    X  65,60 

30(366 

• 

*« 

4594    X  6560 

3013.66 

" 

Wii 

4594    X   65,60 

300.66 

■ 

*,2 

4534    X  65,60 

30O.66 

■ 

TOTAL 

28,629.77 

1000 

0                             £000                      4000 

SCALE   IN    FEET 


J  S.  STRATEGIC  BC*tBING  SURVEY 

UNDERGROUND      PLANTS 

SHAKUTANI 

FWUHE  12   I 


r 


USHIGAYA  STONE  QUARRY 


LEGEND 


ELEVATION  ABOVE 
SEA  LEVEL 


ROOF   HEIGHT 


Ua  STRATEGIC   BOMBINo   SURVEY 
UPPER  LEVELS  OF  PLANT  AT 

SAKAE 

Fie.  13 


43 


44 


il 


45 


UNDERGROUND  FACTORY  LAYOUT 
(machine    shop) 


•OALi  m  ntr 


.o. 


:o! 


r<^ 


I  1     MACHWE  TOOL    (oM  pits  of  clMning  sond  uMd 

in  plodng  of  nMcMn*  tool) 

^^g    POWER  HOUSE  EQUIPMENT    («wfteti  bott  ttc.) 
PASSAGE 


HIGHER  FLOOR  {viry   dongtrout  in  this  or«o 

a  bilow  bocous*  of  lonMidM) 


us  inMt&it  Muem  ajBVEV  ■ 


N(SAI  UNOERGROUNO  WORKS 
OF  MITSUBISHI 


1l»t^   O  .  4T  (PI»  t    Ml 


HISAl 


The  Hisai  plant  (Fig.  15)  was<  ouly  one  of  a 
series  of  iin(lei<ii()nn(l  plants  in  tunnels  which  had 
been  dng  j)revi(iusly  to  obtain  sand  for  abrasives. 
Tk  Navy,  Aichi  Aircraft  Co.,  and  the  Sumitomo 
Co.,  in  addition  to  Jritsnbishi,  had  nn<lerground 
plants  here,  all  of  which  were  to  work  in  conjunc- 
tion with  the  Tsu  Naval  Arsenal  in  producing  air- 
craft and  engines. 

The  Hisai  underground  plant,  located  in  the 
low  hills  southwest  of  Nagoya,  was  a  part  of  the 
.Mitsubishi  No.  3  Airframes  Works. 

At  Hisai,  entrances  led  down  to  a  working  level 
some  40  feet  deep.  The  tunnels  had  been  hol- 
lowed out  of  the  sandy  rock  and  very  little  shor- 
ing was  necessary   (Photographs  41-47). 


Concrete  had  been  laid  as  machine  beds  but 
theie  was  no  otiier  paving.  The  machines  were 
crowded  and  working  sjiace  was  restricted.  The 
conunnnicatioiis  tunnels  wei'e  served  l)y  rail  and 
cable  c"ir. 

The  iiiant  was  very  damp.  Working  conditions 
were  poor,  the  machines  were  rusting,  and  pump- 
ing was  necessary  after  a  rain. 

The  estimated  capacity  of  the  plant  when  tin- 
islied  was  1,.")()0  workers  and  .540  machine  tools, 
actually,  300  tools  were  installed,  beginning  in 
■lune  194.5. 

This  plant  was  dangerous  in  several  areas  be- 
cause the  tunnels  were  on  two  levels  and  the 
collapse  of  sections  was  imminent. 


47 


Photo  No.  41.  Machine  tools  en  route  to  Hisai. 


Photo  No.  42.  Entrance  at  Hisai. 
48 


it 

G 


a 
o 


o 

til 


o 

z 

o 
o 

X 


49 


"3 

O 

_2 

-f 

6 
Z 

0 
0 


50 


Photo  No.  45.  Interior  at  Hisai. 


Photo  No.  46.  Interior  at  Hisai. 
51 


52 


PART  III 
MINOR  AIRCRAFT  COMPANIES 


SOGO  DEPARTMENT  STORE  PLANT  OF  THE  SUMITOMO  COMPANY 


111  Osaka,  tlie  si'cond  and  lliird  haseiiieiits  of 
lie  Sojjo  Co.  l>ei(artnu'iit  Ston-  were  used  by  the 

uinitomo  Co.  for  the  maeliiiiing  of  propeller 
iirts. 

Xot  strictly  an  iiiidergroniid  jilaiit,  the.se  base- 
iciit.s  were  inspeeted  to  complete  the  picture  of 
ic  various  types  of  underground  installations. 

.V  total  of  167  machine  tools  operated  here  for 

period  of  3  months  in  wliat  appeared  to  be  an 
ii-derly  and  well-managed  production  line. 

The  machine  tools  had  been  lowered  into  tlie 
isements  througji  holes  that  had  been  cut  in  the 


sidew;ilk  adjoining  the  building.  This  work  had 
been  carried  out  at  night  so  as  to  conceal  tlie 
whole  operation.  The  heavier  machines  were  in 
the  third  basement  and  the  lighter  ones  in  the 
second  basement. 

In  great  contrast  to  the  tunnel  plants,  these 
basements  offered  no  unusual  ojienitional  prob- 
lems, were  clean,  light,  dry,  and  efficient.  Further- 
more no  external  evidence  was  visible  to  (he  photo 
interpreter  of  the  actual  work  taking  place  here. 

This  plant  was  visited  on  30  October  194;). 


HANDA 


The  Handa  underground  plant  of  the  Sumitomo 
II.  was  a  part  of  the  network  of  underground 
ants  southwest  of  Tsu  (40  miles" southwest  of 
agoya)  to  serve  the  Tsu  Naval  Arsenal  (Fig.  16). 
This  plant  was  similar,  but  superior  to,  the 
isai  plant  of  Mitsul>ishi  whicli  adjoined  it.  The 
iiinels  were  enlarged  out  of  tunnels  which  had 
■en  dug  previously  to  furnish  sand  for  abrasives. 
Frequent  shoring,  cement  spray  on  the  walls, 
■ip  guards  over  the  maciiines.  concrete  floors, 
joping  levels,  and  drainage  gutters  were  char- 
'teristics  of  this  plant.    Pumping  was  necessary 


on  occasion  to  lemove  tlie  water.  (Photographs 
48-51.) 

There  were  no  rail  communication  tunnels  as 
at  Hisai  and  the  machines  were  moved  in  by 
hand. 

Enlarging  of  tunnels  Iiegan  in  March  194")  and 
completion  was  planned  for  Septemhei-.  Of  a 
jilanned  4,500  employees  and  640  machine  tools, 
725  employees  and  271  machines  were  at  work. 

Handa  was  to  produce  ]iropeller  parts.  The 
plant  was  in  operation  but  only  a  few  parts  had 
been  finished. 


53 


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UNDERGROUND   PLANT  LAYOL 


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SCALE  IN  FE£T 


US    STRATEGIC  BOMBING  SURVEY 

suMrroMO  underground  plant 

AT 

HANDA.TSU  CITY 

FIGURE  16 


Photo  No.  48.  Interior  at  Handa. 


Photo  No.  49.  Entrance  at  Handa. 
55 


Photo  No.  50.  Handa  plant.  Tunnels  in  sand  mines  near  Tsu  City. 


Photo  No.  51.  Handa  plant.  (Note  production  tunnels  opening  into  communications  tunnel.) 

56 


TAKATSUKI 


The  Takatsiiki  nii(l('ij>i-oiiiHl  plant  of  the  Kawa- 
saki Aii-cralt  ("o.  was  located  near  Nai'iai  village 
(III  the  outskirts  of  Takatsuki,  which  is  midway 
between  Osaka  and  Kyoto. 

t)riginally  intended  for  use  as  a  central  Army 
warehouse,  these  tunnels  were  begun  in  November 
IWi  by  the  government.  Their  use  by  Kawasaki 
was  not  ordered  until  February  1945.  A  force  of 
3,500  Koreans  living  in  the  valley  was  engaged 
in  the  construction  of  this  plant. 

The  tunnels,  totaling  a  planned  300,000  square 
feet  of  floor  area,  were  laid  out  in  tw^o  adjoining 
iiills,  but  only  one  area  had  reached  any  appre- 
ciable stage  of  completion  (Fig.  17). 

Tlie  completed  tunnel  system  was  halfway  up 
a  roughly  circular  hill,  1,680  feet  in  height.  Laid 
out  in  a  grid  network  were  16  tunnels  with  100,000 
square  feet  of  floor  area  and  a  planned  machine 
tool  capacity  of  550.     However,  only  six  tunnels 


were  near  production.  Forty  machine  tools  and 
electric  power  had  been  installed  and  production 
was  to  get  under  way  on  or  about  UO  August  1945. 

Mute  evidence  of  the  cessation  of  the  war  could 
be  seen  in  the  abandonment  of  machine  tools 
poised  over  the  edge  of  a  cliff,  preparatory  to  be- 
ing hauled  into  the  tunnels.  Steel  plates  were 
used  as  a  base  for  sliding  the  tools  into  place  in 
the  tunnels. 

At  the  time  of  inspection,  30  October  1945,  the 
tunnels  were  fairly  wet  despite  the  fact  that  sev- 
eral of  them  were  faced  with  concrete.  Timber, 
expected  to  last  for  year  and  a  half,  was  used  in 
many  places  as  shoring. 

At  a  later  date  the  company  expected  to  install 
electric  heating  and  ventilating. 

This  plant  was  constructed  for  the  purpose  of 
making  parts  for  the  Ha-140  inline  engine  for 
Tony  II. 


SETO 


The  Aiclii  Aircraft  Co.  dispersed  a  part  of  its 
works  to  tlie  hills  north  of  Seto,  a  town  about  ten 
miles  east  of  Nagoya. 

A  planned  and  completed  floor  area  of  110,000 
s(|uare  feet  was  excavated  in  Ave  areas,  under  five 
adjoining  hills.  However,  only  45,000  square  feet 
were  in  use. 

The  tunnels  formed  an  irregular  pattern  (Fig. 
IS).  They  were  fairly  spacious  but,  in  the  usual 
fashion   of   underground    plants    were    wet    and 


damp.  Shoring  was  necessary  throughout.  (Photo- 
graphs 52-61.) 

This  plant  was  to  make  wings  for  Judy  at  first, 
and  later,  to  make  the  entire  airframe  except  for 
linal  assembly. 

It  was  planned  to  install  800  machine  tools,  of 
which  about  half  were  ready  for  use.  Production 
was  under  way  by  15  August  1945  but  only  a  few 
wing  spars  were  made. 


57 


58 


I 


Photo  No.  52.  Cave-in  of  machine  shop  at  Seto. 


Kff^^^^t^ 

^^^^9 

I  ■ 

^l^p^^i 

yy.%.»^v.j^3 

^^ 

-^^^'''*  wii 

/jjlj^l 

.-        f 

jj^_  ,          9g.^ 

"^gj^-.-^ay.      -.  •-•*!:•  ^: .-  r'    - 

Photo  No.  53.  Entrance  in  spur  of  hill  at  Seto. 

59 


Plioto  No.  54.  Camouflaged  entrance  at  Seto. 


Photo  No.  55.  Entrance  at  Seto. 
60 


■"i/v    '^^  •-,.■  S'.tN- 


Photo  No.  56.  Entrance  at  Seto. 


Photo  No.  57.  Surface  building  at  Seto. 
61 


Photo  No.  58.  Seto  plant.  (Note  extensive  shoring.) 


Photo  No.  59.  Seto  plant.  (The  tight  working  quarters  shown  here  were  not  uncommon.) 

62 


Photo  No.  60.  Interior  at  Seto. 


Photo  No.  61.  Interior  at  Seto. 

63 


HIRO  PLANT  OF  llTH  NAVAL  AIR  DEPOT 


Plans  for  underground  production  were  made 
in  April  1944.  Construction  and  conversion  of 
the  tunnels  were  begun  in  November  1944.  The 
first  movement  of  equipment  to  the  underground 
tunnel  was  in  January  1945.  The  principal  under- 
ground facilities  were  converted  from  a  large 
undei'ground  hangar  which  had  been  built  in  1940, 
and  an  adjoining  road  tunnel.  Actual  production 
was  begun  in  these  tunnels  at  the  end  of  January 
1945.  It  was  planned  to  move  all  the  smaller  ma- 
chines to  these  tunnels.  One-half  of  the  remaining 
large  machines  were  to  stay  in  the  surface  build- 
ings at  Hire,  while  the  other  half  were  to   be 


moved  to  Takihara.  This  movement  was  to 
completed  by  June  1946.  At  the  time  of  the  ; 
raid  on  Hiro  on  5  May  1945,  over  90  percent 
the  small  and  medium  sized  machines  had  alrea 
been  moved  underground.  At  the  end  of  the  v 
about  99  percent  of  the  machines  had  been 
stalled  in  the  underground  plants. 

In  June  1945,  the  Hiro  Navy  Yard  converted 
facilities  for  making  marine  engines  to  the  maj 
facture  of  aircraft  parts.     Its  machines  were 
eluded  in  the  underground  dispersal.     Plans 
these  underground  plants  called  for  product: 
of  400  engines  a  month  by  April  1945. 


UNDERGROUND  PLANTS 


Intelligence  Check 


Wiutime  knowledge  of  Japanese  underground 
installations  was  extremely  meager.  The  Allies 
knew  the  locations  of  only  three  installations  and 
nothing  more.  This  was  probably  due  to  the  fact 
that  the  underground  program  was  not  really 
begun  until  the  last  year  of  the  war  and  there  was 
not  enough  time  for  the  information  to  seep  out 
into  Allied  hands. 

Anotlier    cause    was    the    difficulty    of    finding 


underground  tunnels  through  air  photo  inter| 
tation.  Postwar  photography  and  interpretati 
even  when  based  on  information  supplied 
USSBS,  was  unable  to  find  most  of  the  entran 
at  the  locations  that  had  been  studied  by  USS 
And  it  was  impossible  to  state  how  extensive- 
underground  plant  might  be  or  what  activity  i 
being  conducted  in  it. 

The  principal  way  of  learning  about  un( 
grounds  would  seem  to  be  by  POW  interrogati 
augmented  by  air  photographs. 


64 


late 
irtl 
inal 


CONCLUSIONS 


"lie  .Tiijianese   underground  installatious  wei-e 

nil  too  late  for  them  to  be  able  to  save  the  pro- 

liiiii  of  aircraft.     In  any  event,  their  existence 

111  not  have  overcome  other  problems  such  as 

I  la.ues  of  vital  raw  materials  and  fuel. 

I  instruction   methods  do  not  reveal  anything 

t  is  new  or  that  is  not  already  known  to  the 

1  engineering  profession.     Only  the  profusion 

iiiinels,  caves,  and  mines  is  impressive. 

iiherent  dampness  wreaked  havoc  with  preci- 

luachinery  and  with  the  health,  morale  and 

iiy  of  workers.     Air-conditioning  and  water 

iuage  were  necessai-y  for  any  long  period  of 

.It ion,    if    machinery    was    to    be    protected 

I  list  rust  and  corrosion  and  still  be  in  use. 

iildition,  workers  need  to  be  fortified  with  an 

mate  diet.    Workers  also  need  plenty  of  light 

luk  by.    Sun  lamps  would  probably  have  been 

licial  to  the  workers. 

nderground  production  probably  suffered  from 
lack  of  free  and  simple  transport  such  as  is 
i  liable  in  a  compact,  well-planned  surface  fac- 


Interdiction  of  highways  and  raili-oads  leading 
to  an  underground  retarded  production  by  ob- 
structing the  receipt  of  materials  and  tiie  delivery 
of  finished  goods.  Destruction  of  electiic  power 
sources  might  have  had  the  same  effect. 

The  principal  advantages  of  an  underground 
in.stallation  are  that  it  is  hard  to  find,  makes  a 
very  poor  target  and  would  probably  l)e  safe  from 
any  weapon  used  in  the  second  World  War.  Heavy 
gases  would  make  an  underground  untenable  but 
could  be  countered  by  air  purification  devices. 
Bacteria  would  be  effective  against  workers  whose 
vitality  and  resistance  had  been  lowered  by  work- 
ing underground. 

However,  in  spite  of  the  disadvantages,  it  would 
seem  advantageous  for  any  nation  to  ]int  some  of 
its  more  vital  production  facilities  into  adequately 
prepared  underground  locations.  If  the  Japanese 
had  made  an  earlier  start  on  their  underground 
program  their  underground  and  dispersal  plants 
might  have  constituted  a  more  serious  problem 
for  the  Allies. 


65 


UNITED  STATES  STRATEGIC  BOMBING  SURVEY 
LIST  OF  REPORTS 


The  following  is  a  bibliography  of  reports  i-esulting 
from  the  Survey's  studies  of  the  European  and  Pacific 
wars.  Those  reports  marked  with  an  asterisk  (*)  may 
be  purchased  from  the  Superintendent  of  Documents  at 
the  Government  Printing  Office,  Washington,  D.  C. 

European  War 
OFFICE  OF  THE  CHAIRMAN 

•1  The  United  States  Strategic  Bombing  Survey  :  Sum- 
mary Report   (European  War) 

*2  The  United  States  Strategic  Bombing  Survey : 
Over-all  Report   (European  War) 

*3  The  Effects  of  Strategic  Bombing  on  the  German 
War  Economy 

AIRCRAFT  DIVISION 

(By  Division  and  Branch) 

*4     Aircraft  Division  Industry  Report 

5  Inspection    Visits    to    Various    Targets     (Siiecial 

Report ) 

Airframes  Branch 

6  Junkers  Aircraft  and  Aero  Engine  Works,  Dessau, 

Germany 

7  Erla  Maschinenwerke  GmbH,  Heiterblick,  Ger- 

many 
S    A  T  G  Maschinenbau,  G  ni  b  H,  Leipzig  (Mockau), 

Germany 
9     Gothaer  Waggonfabrik.  A  G,  Gotha,  Germany 
10     Focke  Wulf  Aircraft  Plant,  Bremen,  Germany 

Over-all  Roiwrt 


11     Messerschmitt  A  G, 

Augsburg,  Germany 


Part  A 
Part  B 
ApiK-ndices  I,  II,  III 

12  Dornier    Works,    Friedrichshafen    &    Munich,    Ger- 

many 

13  Gerhard  Fieseler  Werke  G  m  b  H,  Kassel,  Germany 

14  Wiener  Xeustaedter   Flugzeugwerke,   Wiener  Neu- 

stadt,  Austria 

Aero  Engines  Branch 

15  Bu.ssing  XAG  Flugmotorenwerke  G  m  b  H,  Bruns- 

wick, Germany 
1<>     Mittel-Deufsche  Molorenwerke  G  ni   li   II.  Taucha, 

Germany 
IT     Bavarian  Motor  Works  Inc.  Eisenach  &  Durrerhof, 

Geimany 

18  Bayerische   Molorenwerke   A    G    (BMW)    Munich, 

Germany 

19  Henschel  Flugmotorenwerke,  Kas.sel,  Germany 


Light  Metal  Branch 

20  Light  Metals  Industry    (Part  I,  Ahnninnm 

of  Germany  )Part  II,  Magnesium 

21  Vereinigte  Deutsche  Metallwerke,  Hildesheim,  Gi 

many 

22  Metallgussgesellschaft  G  m  b  H,  Leipzig,  Genua 

23  Aluminiumwerk  G  m  b  H,  Plant  No.  2.  Bitterfe 

Germany 

24  Gebrueilcr  (Jinlini   G   m   b   H,   Ludwigshafen,  6' 

many 

25  Lnftschitfbau.  Zeppelin  G  m  b  H,  Friedrichshaf 

on  Bodeusee,  Germany 

26  Wieland  Werke  A  G,  Ulm,  Germany 

27  Rudolph  Rautenbach  Leichmetallgiessereien,  Sol 

gen,  Gei-inany 

28  Lippewerke     Vereinigte     Aluminiumwerke     A 

Lnnen.  Germany 

29  Vereinigte    Deutsche    Metallwerke,     Heddernhei 

Germany 

30  Duerener  Metallwerke  A  G,  Duren  Wittenau-Be^ 

&  Waren.  Germany 

AREA  STUDIES  DIVISION 

*31     Area  Studies  Division  Report 

32  A  Detailed  Study  of  the  Effects  of  Area  Bomb> 

on  Hamburg 

33  A  Detailed  Study  of  the  Effects  of  Area  Bombi 

on  Wuppertal 

34  A  Detailed  Study  of  the  Effects  of  Area  Bomb 

on  Dusseldorf 

35  A  Detailed  Study  of  the  Effects  of  Area  Bomb: 

on  Solingen 

36  A  Detailed  Study  of  the  Effects  of  Area  Bomb) 

on  Remscheid 

37  A  Detailed  Study  of  the  Effects  of  Area  Bombi 

on  Darmstadt 

38  A  Detailed  Study  of  the  Effects  of  Area  Bombi 

on  Lulieck 

39  A  Brief  Study  of  the  Effects  of  Area  Bombing 

Berlin,  Augsburg,  Bochum,  Leipzig,  Hagen,  Do 
mund,  Oberhausen,  Schweinfurt,  and  Bremen  i 

CIVILIAN  DEFENSE  DIVISION 

*40  Civilian  Defen.se  Division — Final  Report 

41  Cologne  Field  Rejwrt 

42  Bona   Field   Report 

43  Hanover  Field  Report 

44  Hamburg     Field     Rei)ort— Vol     I,    Text;    Vol 

Exhibits 

45  Bad  Oldesloe  Field  Report 

46  Augsburg  Field  Report 

47  Keception  Area   in  Bavaria,  Germany 


66 


EQUIPMENT  DIVISION 

Electrical  Branch 

(icnuiiii  lOU'ctricMl  E(juipmoiit  Industry  Kcport 
Hrowii  Boveri  et  Cie,  Mannheim  Kafertal,  Germany 

Optical  and  Precision  Instrument  Branch 

iiptical  and  rrccisidii  Iiislnnnont  Industry  Report 

Abrasives  Branch 

The  Gornuin  Abrasive  Industry 

.Mayer  and  Schmidt,  Offenbach  on  Main,  Germany 

Anti-Friction  Branch 

riie  German  Anti-Friction  Bearings  Industry 

Machine  Tools  Branch 

Maelune  Tools  &  Machinery  as  Capital  Equipment 
.Machine  Tool  Industry  in  Germany 
I  [erman  Kolb  Co.,  Cologne,  Germany 
I'ollet  and  Engelhard,  Offenbach,  Germany 
Xaxos  Union,  Frankfort  on  Main,  Germany 

MILITARY  ANALYSIS  DIVISION 

I'lie  Defeat  of  the  German  Air  Force 

\   Weapons   (Crossbow)    Campaign 

Air  Force  Kate  of  Operation 

Weather  Factors  in  Combat  Bombardment  Opera- 
tions in  the  p]uroi)ean  Theatre 

I'.iinibing   Accuracy,    USAAF  Heavy   and    Medium 
Bombers  in  the  ETO 

I  icscription  of  RAF  Bombing 
.  The  Impact  of  the  Allied  Air  Effort  on  German  Lo- 
gistics 

MORALE  DIVISION 

iJ  I  he  Kft'ects  of  Strategic  Bombing  on  German 
Morale   (Vol  I  &  II) 

Medical  Branch 

I  i'lic  Effect  of  Bombing  on  Health  and  Medical  Care 
in  Germany 

MUNITIONS  DIVISION 

Heavy  Industry  Branch 

11  i'lie  Coking  Industry  Rejwrt  on  Germany 
i  Inking  Plant  Reixtrt  No.  1,  Sections  A,  B,  C,  &  D 
-  liiitehoffnung.shuette,  Oberhausen,  Germany 
«  Friedrich-Alfred  Huette,  Rheinhausen,  Germany 

0  Xeunkirchen   Eisenwerke  A   G,   Neunkirchen,   Ger- 

many 

1  Ivfichswerke   Hermann   Goering   A   G,   Hallendorf, 

<Jermany 

i  August  Thys.sen  Huette  A  G.  Ilamborn,  Germany 

'3  Friedrich  Krupp  A  G,  Borbeck  Plant,  Essen,  Ger- 
many 

I  iKiitmund  Hoerder  Huettenverein,  A  G,  Dortmund, 
•  ierniany 

•'  Hiiesch  A  G,  Dortmund,  Germany 

«|Bocliunier  Verein  fuer  Giisstahlfabrikation  A  G, 
Bochum,  Germany 


Motor  Vehicles  and  Tanks  Branch 

•77     German  Motor  Vehicles  Industry  Report 
*78     Tank  Industry  Report 

79  Daimler  Benz  A  (J,  Unterturkheim,  Germany 

80  Renault  Motor  Vehicles  Plant,  Billancourt,  Paris 

81  Adam  Opel,  Russelheim,  (iermany 

82  Daimler    Benz-Gaggenau    Works,    Gaggenau,    Gei'- 

ma  ny 

83  Maschinenfabrik      Angsburg-Nurnberg,      Nurnberg, 

Germany 

84  Auto  Union  A  G,  Chemnitz  and  Zwickau,  Germany 

85  Henschel  &  Sohn,  Kassel,  Germany 

86  Maybach  Motor  Works,  Friedrich.shafen,  Germany 

87  Voigtlander,    Ma.schinenfabrik   A   (J,   Plauen,   Ger- 

many 

88  Volkswagenwerke,   B''allersleben,   Germany 

89  Bussing  NAG.  Brunswick,  Germany 

90  Muehlenbau  Industrie  A  G  (Miag)  Brunswick,  Ger- 

many 

91  Friedrich    Krupp    Grusonwerke,    Magdeburg,    Ger- 

many 

Submarine  Branch 

92  German  Submarine  Industry  Report 

93  Maschinenfabrik    Augsburg-Nurnberg   A    G,   Augs- 

burg, Germany 

94  Blohm  and  Voss  Shipyards,  Hamburg,  Germany 

95  Deutschewerke  A  G,  Kiel,  Germany 

96  Deutsche  Schiff  und   Masehinenbau,   Bremen,  Ger- 

many 

97  Friedrich  Krupp  Germaniawerft,  Kiel,  Germany 

98  Howaldtswerke  A  G,  Hamburg,  Germany 

99  Submarine  Assembly  Shelter,  Farge,  Germany 
100     Bremer  Vulkan,  Vegesack,  Germany 

Ordnance  Branch 

*101     Ordnance  Industry  Report 

102  Friedrich    Krupp    Gruisonwerke    A    G    Magdeburg, 

Germany 

103  Bochumer   Verein   fuer   Gu.sstahlfabrikation   A   G, 

Bochum,  Germany 

104  Henschel  &  Sohn,  Kassel,  Germany 

105  Rheinmetall-Borsig,  Dusseldorf,  Germany 

106  Hermann   Goering   Werke,   Braunschweig,   Hallen- 

dorf, Germany 

107  Hannoverische  Masehinenbau,  Hanover,  Germany 

108  Gu.sstahlfabrik  Friedrich  Krupp,  Essen,  Germany 

OIL  DIVISION 

*109     Oil  Division,  Final  Report 

<110    Oil  Division,  Final  Report,  Appendix 

*111     Powder,  Explosives,  Special  Rockets  and  Jet  Pro- 

pellants.  War  Gases  and  Smoke  Acid  (Ministerial 

Report  #1) 

112  Unilerground  and  Dispersal  Plants  in  Greater  Ger- 

many 

113  The  German  Oil  Industry.  Ministerial  Report  Team 

78 

114  Ministerial  Report  on  Chemicals 

Oil  Branch 

115  Ammoniakwerke  Merseburg  G  ni  b  H,  Leuna,  Ger- 

numy — 2  Appendices 


67 


110  Iii:iniiki)hle  Benzin  A  G,  Zeitz  and  Boblen,  Ger- 
iiKiiiy,  Wintersliall  A  G,  Leiifzkendorf,  Germany 

117  Ludwigsliafen-Oiipini  Works  of  I  G  Farbenindustrio 
A  G,  Ludwig.shafen,  Germany 

lis  Ruhroel  Hydrogenation  Plant,  Bottroi»-r.oy,  Ger- 
many. Vol.  I,  Vol.  II 

119  Rhenanla    Ossag    Mincraloclwerke    A    G,    Ilarlmrg 

Refinery,  Hamburg.  Germany 

120  Rhenauia  Ossag  Mineraloelwerke  A  G,  Grasbrook 

Refinery,  Hamburg,  Germany 

121  Rhenania   Ossag  Mineraloelwerke  A  G,   Willielms- 

burg  Refinery.  Hamlinrg.  Germany 

122  Gewerkschaft    Victor,    Castrop-Rauxel,    Germany, 

Vol.  I  &  Vol.  II 

123  Europaeische  Tanklager  nnil  Transport  A  G,  Ham- 

burg, Germany 

124  Ebano    Asphalt    Werke    A    G,    Harburg    Refinery, 

Hamburg.  Germany 

125  Meerbeck  Rbeinpreussen  Synthetic  Oil  Plant — Vol. 

I  &  Vol.  II 

Rubber  Branch 

12G  Deutsche  Dunlop  Gummi  Co.,  Hanau  on  Main. 
Germany 

127  Continental  Gumniinerke.  Hanover,  Germany 

128  Huels  Synthetic  Rubber  Plant 

129  Ministerial  Report  on  German  Rubber  Industry 


Propellants  Branch 

Elcktrochemischewerke,  Munich,  Germany 

Scboenebeck  Explosive  Plant,  Lignose  SprengstofC 
Werke  GmbH,  Bad  Salzemen,  Germany 

Plants  of  Dynamit  A  G,  Vormal,  Alfred  Nobel  & 
Co,  Troisdorf,  Clausthal,  Drnmmel  and  Dune- 
berg,  German.v 

Deut.scbe  Sprcngcbemie  G  m  b  II,  Kraiburg,  Ger- 
many 

OVERALL  ECONOMIC  EFFECTS  DIVISION 

V.U     Over-all  Economic  Effects  Division  Report 


1.30 
131 

132 


133 


Gross  National  Product 
Kriegseilberichte        . 
Hermann  Goering  Works 
Food  and  Agriculture 


134a  Industrial   Sales  Output  and  Productivity 


Special  pai>ers 
which  together 
comprise  the 
above    report 


134b 

133 

136 

137 

138 

139 

140 

141 

142 

143 

144 

14.J 

140 


PHYSICAL  DAMAGE  DIVISION 

Physical   Damage  Division  Report   (ETO) 

Villaconlilay  Airdrome,  Paris.   France 

Railroad  Repair  Yards,  Malines.  Belgium 

Railroad  Repair  Yards,  Louvain,  Belgium 

Railroad   Ripair  Yards,   Hasselt,   Belgium 

Itailroad   Repair  Yards,  Namur,  Belgium 

Suliniarinc  Pens,  Brest,  France 

Powder  I'lant,  Angouleme.  France 

Powder  Plant,  Bergerac,  France 

Coking  Plants,   Montigny  &  Liege,   Belgium 

Fort  St.  Blaise  Verdun  Group,  Metz,  France 

Gnome  et  Rhone,  Limoges,  France 

MIchelin  Tire  Factory,  Clcrmont-Ferraiid,  Franc 


147  Gnome  et  Rhone  Aero  Engine  Factory,  Le  Ma 

France 

148  Kugelfischer   Bearing   Ball   Plant,    EbeLsbach,  G 

many 

149  Louis  Breguet  Aircraft  Plant,  Toulouse,  France 

150  S.  N.  C.  A.  S.  E.  Aircraft  Plant,  Toulouse,  Fran 
1.51     A.  I.  A.  Aircraft  Plant,  Toulouse,  France 

152  V  Weapons  in  London 

153  City  Area  of  Krefeld 

1.54  Public  Air  Raid  Shelters  in  Germany 

1.55  Goldenberg  Thermal  Electric  Power  Station,  Kb 

sack,  Germany 
1.5C     Brauweiler     Tran.sformer     &     Switching     Stat 
P.rauweiler,  Germany 

157  Storage  Depot,  Nahbollenbacli.  Germany 

158  Railway  and  Road  Bridge.  Bad  Mnnster,  Germ. 

159  Railway  Bridge,  Eller,  Germany 
IfiO    Gustloff-Werke  Weimar,  Germany 

Kil     Ilenschel  &  Sohn  G  ni  b  H.  Ka.s.sel.  Germany 

162  Area   Survey  at  Pirmasens,  Germany 

163  Hanomag,  Hanover,  Germany 

164  M  A  N  Werke  Augsburg.  Augsburg,  Germany 

165  Friedrich  Krupp  A  G,  Essen,  Germany 

1116     Erla  Mascliincnwerke.  (i  ni  b  H.  Heitcrblick,  ( 
many 

167  A  T  G  Maschinenbau  G  m  b  H,  Mockau,  Germ 

168  Erla  Maschinenwerke  G  m  h  H,  Mockau,  Germ 

169  Bayerische   Motorenwerke,    Durrerhof,   Germar 

170  Mittel-Deutsche  Motorenwerke  G  m  1)  H,  Taui 

Germany 

171  Submarine    Pens    Deut.sche-Werft,    Hamburg,  ( 

many 

172  Multi-Storied   Structures,    Hamburg,   Germany 

173  Continental  Gummiwerke,   Hanover,   Germany 

174  Kassel  Marshalling  Yards,  Kassel,  Germany 

175  Amnioniawerke,  Merseburg,  Leuna,  Germany 

176  Brown   Boveri   et   Cie,    Mannheim,    Kafertal,  ' 

m:iny 

177  Adam  Opel  A  G,  Rnsselsheim,  Germany 

178  Dainder-Benz  A.  G,  Interturkheim,  Germany 

179  ^'alentin  Submarine  Assendily,  Fargc,  German' 

180  Volkswaggonwerke,    Fallerslebeu,    Germany 

181  Railway  Viaduct  at  Bielefeld,  Germany 

182  Ship  Yards  Howaldtswerke,  Hamburg,  Germai 

183  Blolim  and  Voss  Shipyards,  Hamburg,  German 

184  Daimler-Benz  A.  G,  Mannheim,  Germany 

185  Synthetic  Oil  I'lant.  Mcerbeck-IIambui'g.  Germt 

186  Gewerk.schaft   Victor,   Castrop-Rauxel,   German 

187  Klockuer  Humboldt   Deutz,   Ulm,   Germany 

188  Ruhroel    Hy.drogenation    Plant,    Bottrop-Boy,  (r 

many 

189  Neukirchen  Eisenwerke  A  G,  Neukirchen,  Germ  f 

190  Railway  Viaduct  at  Altenbecken,  Germany 

191  Railway   Viaduct  at   Arnsburg,  Germany 

192  Denrag-Nerag  Refineries,   Misburg,   Germany 

193  Fire  Raids  on  German  Cities 

194  I  (i  Farbenindustrie,  Ludwigshafen,  Germany.    I 

I  &  Vol  II 

195  Roundhouse  in  Marshalling  Yard,  Ulm,  Genuiii 
190     I  G  Farbenindustrie,  Leverkusen.  Germany 

197  Chemische-Werke,  Heuls,  Germany 

198  Grcndierg   Marshalling  Yard,   Grenilierg,  Germil' 

199  Locomotive  Sliups  and  P.ridges  at  Ilaiinn,  Germi'' 


li. 


li- 


es 


TRANSPORTATION  DIVISION 

I     'I'lic    EllVcls    of    Sti-:ilryic     I'.oinliiiiK    uii    (ici-many 

'I'vausiKivtatidii 
(     i;.iil  Operations  Ovci-  llif  Itrcniicr  I'ass 
I     i:rr('cls   of   Bombing   on    Kailroad    Insfallatioiis   in 
Ito^'enslnng,  Nurnljerg  and  Miniicli  Divisions. 
German  Locomotive  Industry  During  the  War 
German  Military  Ttailroad  Tratlie 

UTILITIES  DIVISION 

German   Electric   Utilities   Industry  Report 

I  to  10  in  Vol  I  "Utilities  Division  Plant  Reports"' 

II  to  20  in  Vol  II  "Utilities  Divisi(m  Plant  Re- 
ports" 

'21  Klieiniselie-Westfalisclie  Elektrizitaetswerk  A  G 

Pacific  War 

OFFICE  OF  THE  CHAIRMAN 

Summary  Report  (Pacific  War) 
Japan's  Struggle  to  End  The  War 
The  Effects  of  Atomic  Bombs   mi    llirnsliima    and 
Nagasaki 

CIVILIAN  STUDIES 
Civilian  Defense  Division 

Field    Report    Covering   Air    Raid    Protection    and 

Allied  Subjects,  Tokyo.  Japan 
Field    Report    Covering   Air    Raid    Protection    and 

Allied  Subjects,  Nagasaki,  Japan 
Field    Report    Covering   Air    Raid    Protection    and 

Allied  Subjects,  Kyoto,  Japan 
Field    Report    Covering   Air   Raid   Protection   and 

Allied  Subjects,  Kobe,  Japan 
Field    Report   Covering   Air    Raid    Protection    and 

Allied  Subjects,  Osaka,  Japan 
Field    Report    Covering   Air    Raid    Protection    and 

Allied  Subjects,  Hiroshima,  Japan — No.  1 
Summary    Report    Covering    Air    Raid    I'rotection 

and  Allied  Subjects  in  Japan 
Final    Report   Covering   Air   Raid    Protection   and 

Allied  Subjects  in  Japan 

Medical  Division 

The  Effects  of  Bombing  on  Health  and  Medical 
Services  in  .Japan 

The  Effects  of  Atomic  Bombs  on  Health  and  Med- 
ical  Services  in  Hiroshima  and   Nagasaki 

Morale  Division 

The    Effects    of    Strategic    Bombing    on    Japanese 
rale 


ECONOMIC  STUDIES 
Aircraft  Division 


5  The  Japanese  Aircraft  Industry 
'J  Mitsubishi  Heavy  Industries,  Ltd. 
Corporation  Report  No.  I 

(Mitsubishi  Jukogyo  KK) 
(Airframes  &  Engines) 


*17     Nakajima  Aircraft  Company,  Lid. 
Corporation  liepurt  A'o.  // 
(Nakajima  Hikok  KK) 
(Airframes  &  Engines) 
*18     Kawanishi  Aircraft  Company 

i'orporation   licjiort   Ao.   /// 

(Kawanislii   KokiiUi   Kiibusblki   Kaislia) 
(Airframes) 

*19     Kawasaki  Airei'aft    Industries  Company,   Inc. 
C'orporaiio)!  Hiport  .\o.  IV 

(Kawasaki      Kokuki      Kogyo      Kabushiki 

Kaisha ) 
(Airframes  &  Engines) 

*20     Aiclii  Aircraft  Comi)any 

CorponitioH   Report  Xo.   V 
(Aichi  Kokuki  KK) 
(Airframes  &  Engines) 

*21     Sumitomo  Metal  Industries,  Proijeller  Divi-sion 
Corporation  Report  Xo.  VI 

(Sumitomo  Kinzoku  K(isyci  KK,  Pnropera 

Seizosho) 
( Propellers  1 

*22     Hitachi  Aircraft  Company 

Corporation  Report  Xo.  VII 
(Hitachi  Kokuki  KK) 
(Airframes   «&   Engines) 

Japan   International  Air  Industries,  Ltd. 
Corporation  Report  Xo.  VIII 

(Nippon  Kokusai  Koku  Kogyo  KK) 
(Airframes) 

Japan    Musical    Instrument    Manufacturing    Com- 
pany 

Corporation  Report  Xo.  IX 
(Nippon  Gakki  Seizo  KK) 
(Propellers) 

*2.">     Tacbikawa   Aircraft  Company 
Corporation  Report  Xo.  X 
(Tacbikawa  Hikoki  KK) 
(Airframes) 
*2('i     Fuji  Airplane  Company 

Corporation  Report  Xo.  XI 
(Fuji  Hikoki  KK) 
(Airframes  I 
*27     Shdwa  Airplane  Company 

Corporation  Report  Vo.  XII 

(Showa  Hikoki  Kogyo  KK) 
(Airframes) 
*2S     Lshikawajima  Aircraft  Industries  Company,  Ltd. 
Corporation  Report  No.  XIII 

(lshikawajima     Koku    Kogyo     Kabushiki 

(Kaisha) 
(Engines) 
*20     Nippon  Airplane  Company 

Corporation  Report  Xo.  XIV 
(Nippon  Hikoki  KK) 
(Airframes) 
*30     Kyushu  Airplane  Comiiany 

Corporation  Report  No.  XV 
(Kyushu  Hikoki  KK) 
(Airframes) 


*2;^ 


*24 


69 


*31     Shoda  Engineering  Company 

Corporation  Rvvort  No.  XVI 
(Slioda  Seisakujo) 
(Comiwneuts) 
•32     Mitaka  Aircraft  Inilustries 
Corporation    Heport    A'o 


xrii 

(Mitaka  Kokvi  Kngyo  Kaluisliiki   Kaislia) 
( ('uuii)iinents) 
♦33     Nissan   Aiitonioliile   Company 

Corporation  Rvport  Xo.  XVIII 
(Nissan  Jidoslia   KK ) 
(Engines) 
»34     Army  Air  Arsenal  &  Xavy  Air  Depots 
Corporation  Report  No.  XIX 
(Airframes  and  Engines) 
*35     Underground   Production  of  Japanese  Aircraft 
Report  Xo.  XX 

Basic  Materials  Division 

•30     Coal  and  Metals  in  Japan's  War  Ecouomy 

Capital    Goods,   Equipment    and   Construction    Division 

*37     The  Japanese  Construction  Industry 

*38    Japanese  Electrical  Equipment 

*39    The  Japanese  Machine  Building  Industry 

Electric  Power  Division 

*40    The  Electric  Power  Industry  of  Japan 
•41     The  Electric  Power  Industry  of  Japan   (Plant  Re- 
ports) 

Manpower,  Food  and  Civilian  Supplies  Division 

*42     The   Japanese  Wartime    Standard   of   Living   and 
Utilization   of   Manpower 

Military  Supplies  Division 

•43  Japanese  War  Production  Industries 

•44  Japanese  Naval  Ordnance 

45  Japanese  Army  Ordnance 

*46  Japanese  Naval  Shipbuilding 

•47  Japanese  Motor  Vehicle  Industry 

•48  Jai>anese  Merchant  Shipbuilding 


49 
50 
51 

52 


•53 


Oil  and  Chemical  Division 

Chemicals  in  Japan's  War 

Chemicals  in  Japan's  War — Appendix 

Oil  in  Japan's  War 

Oil  in  Japan's  War — Appendix 

Over-all  Economic  Effects  Division 

The  Effects  of  Strategic  Bombing  on  Japan's  War 
Economy  (Including  Appendix  A:  U.  S.  Eco- 
nomic Intelligence  on  Japan — Analysis  and  Com- 
IKirison;  Appendix  B:  Gross  National  Product 
on  Japan  and  Its  Cunipononts;  Appendix  C: 
Statistical  Sources). 

Transportation  Division 

•M     The  War  Against  Japanese  Transportation,   1941- 
1945 


60 


Urban  Areas  Division 

Effects  of  Air  Attack  on  Japanese  Urban  Econ 

(Summary  Report) 
Effects  of  Air  Attack   on   Ihban  Complex  To 

Kawasaki-Yokohama 
Effects  of  Air  Attack  on  the  City  of  Nagoya 
Effects  of  Air  Attack  on  Osaka-Kobe-Kyoto 
Effects  of  Air  Attack  on  the  City  of  Nagasaki 
Effects  of  Air  Attack  on  the  City  of  Hiroshim 


MILITARY  STUDIES 
Military  Analysis  Division 

61  Air   Forces   Allied   with   the   United   States  in 

W^ar  Against  Japan 

62  Japanese  Air  Power 

63  Japanese  Air  Weapons  and  Tactics 

64  The    Effect    of   Air    Action    on    Japanese    Gr 

Army  Logistics 

65  Employment     of     Forces     Under     the     South 

I'acitic  Command 

06  The     Strategic    Air    Ol>erations    of    Very    H 

Bombardment     in     the     War     Against     J 
(Twentieth  Air  Force) 

07  Air    Operations    in    China,    Burma,    India— "V 

War  II 
OS     The  Air  Transport  Command  in  the  War  Ag 

Japan 
09     The    Thirteenth    Air    Force    in    the    War   Ag 

Japan 

70  The  Seventh  and  Eleventh  Air  Forces  in  the 

Against  Japan 

71  The  Fifth  Air  Force  in  the  War  Against  Japi 

Naval  Analysis  Division 

*72    The  Interrogations  of  Japanese  Officials   (V' 

and  II) 
*73     Campaigns  of  the  Pacific  War 
*74     The  Reduction  of  Wake  Island 
*75     The  Allied  Campaign  Against  Rabaul 
76    The   American    Campaign    Against    Wotje,   1 

lap,  Mille,  and  Jaluit  (Vols.  I,  II  and  III) 
*77     The  Reduction  of  Truk 

78  The    Offensive    Mine    Laying    Campaign    Af 

Japan 

79  Reiwrt    of    Ships    Bombardment    Survey    Pa 

Foreword,    Introduction,    Conclusions,   and 
eral  Summary 

80  Report  of  Ships  Bombardment  Survey  Party 

closure  A),  Kamaishi  Area 

81  Reiwrt  of  Ships  Bombardment  Survey  Party  5l 

closure  B),  Hamamatsu  Area 

82  Report  of  Ships  Bombardment  Survey  Party  5) 

closure  C),  Hitachi  Area 

83  Report  of  Ships  Bombardment  Survey  Partj 

closure  D),  Hakodate  Area 

84  Report  of  Ships  Bombardment  Survey  rart.\ 

closure  E),  Muroran  Area 

85  Report  of  Ships  Bombardment  Survey  Parlj 

closure  F),  Shimizu  Area 

86  Report  of  Ships  Bombardment  Survey  Party  '"' 

closures  G  and  II),  Shionomi-Saki  and  NoM 
Saki  Areas 


70 


IJipori  (it'  Ships  I!oiMli:ir(liiii'iil  Survey  I'lirly  (Kii- 
iliiMiri'   I  I,  ( '(Uiiinc'iils  ;iii(l    l):il:i   on   Kft'i'ctivciiess 

nl'    AllllllUIlitidll 

1;^  port  (if  Ships  Bdiiiliardiiiciil    Siii'vcy  I'afty   (Eii- 

(  IdSiire  .1).   ('(iiiiinciils  Mild   Unta   (in   Accuracy  of 

I'ii'iii:;- 
Kipdi-ts  (if  Ships  P.oiiilianliiK'iit  Survey  I'arty  (Eii- 

I  Insure  K),  lOffects  (if  Surface  Kdiiiliariliiii'iits  on 

.la]>aiiese   War  I'oleiitial 

Physical  Damage  Division 

Kffect  of  llie  Incendiary  Bonili  Atta(ks  on  Japan 
(a   Heiiort  on  Eight  Cities  I 

The  EfftH-t.s  of  the  Ten  Thousan<l  I'ouud  Homb  on 
.Tapanese  Targets   (a   lieixirt  on  Nine  Incidents) 

Effects  of  the  Atomic  I'.onili  on   Ilirdshinia,  Japan 

Kffects  of  the  Atomic  Bomh  on  Nagasaki,  Japan 

Effects  of  the  Four  Thousand  round  Bomii  (ni 
Japanese  Targets   (a  Keiiort  on  Five  Incidents) 

Effects  of  Two  Thousand,  One  Thousand,  and  Five 
Hundred  Pound  Bombs  on  Japnne.se  Targets  (a 
Iteport  on  Eight  Incidents) 

i.  Itejiort  on  Ph.vsical  Damage  in  J.ipan  (Sum- 
mary  I!ei>ort) 

G-2  Division 

lapanese    Military   and    Naval    Intelligence 


!>.S 

Evalnalidii 

.lai>a  nese 

liiiii 

ill) 

Ev.-ilnalioH 

Japanese 

I  (Id 

Evaluation 

.Faiianese 

/'loltiiii/ 

101 

Evaluation 

Jajianese 

tlljl-sis 

l(t2 

Evaluatidii 

Japanese 

](« 

Ev;iluation 

.T.-ijianese 

1(14 

Evaluation 

Jai)anese 

Kl.'i 

Evaluation 

Japanese 

Hciicc 

km; 

Evaluation 

Japanese 

1(17 

Evaluation 

Jaiianese 

roads 

108 

Evaluation 

Japanese 

(llll-lif; 

(it  I'lioldgr.ipliic  Intelligence  in  the 
Ildirielaiid.  I'arl  I,  lidiiiiinlirniivi;  Re- 
nt' I'hdlograiiliic  liitelligenoe  in  the 
Homeland,  Pari  II.  .Mr/ifUls 
of  Photographic  Iiitelligetice  in  the 
Homeland.    Pari    III,   Cdinpiitcil   Homli 

of    Photographic     Intelligence     in     the 
Homeland.   I'.-irt    I\',    irhaii   Arc<t   An- 

of    Phdlographic    Intelligeneo    in    the 
Homeland,    Pail    V,    Ciimoufliiiic 
of    I'hotographic     Intelligence    in    the 
Homeland,   Part   VI,   Shiiiiihitj 
of    Photograpinc     Intelligence    in    the 
Homeland,  I'art   VII,  J'JIeclrfjiiif.t 
of    Photographic    Intelligence    in    the 
Homeland,    Part    VIII,    Jliiich   lutrlli- 

of    Photogiai)hic    Intelligence    in    the 
Homeland,   Part   IX,  Artillery 
of    Photographic    Intelligence    in    the 
Homeland,    Part    X,   Roads   and   Rail- 

of    Phot(jgraphic    Intelligence    in    the 
Homeland,    Part    XI,    Industrial   An- 


■V-U.    S.   GOVERNMENT  PRINTING   OFFICE:    1947 714387 


71 


^'\o  'bO 


I  no   3  \ 
s    i£>  '5  3