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Nakajima Ki-62

Nakajima Ki-62

Nakajima Ki-62

Die Nakajima Ki-62 was 'n ontwerp vir 'n vegter wat aangedryf sou word deur die Japannese weergawe van die Daimler-Benz DB 601A-enjin, vervaardig indien die Kawasaki Ki-61-ontwerp misluk.

Kawasaki het die regte gekoop om die DB 601A-enjin in Japan te bou, waar dit die naam Ha-40 gekry het. Hulle is toe (1940) beveel om twee vegvliegtuie rondom hierdie enjin te ontwerp, die swaar afsnyer Ki-60 en die algemene doel Ki-61. Teen hierdie datum het die Japanse weermag se weermag sy mededingende tenders laat vaar en in plaas daarvan 'n enkele onderneming opdrag gegee om elke nuwe ontwerp te vervaardig, maar dit was 'n geruime tyd sedert Kawasaki 'n vegter vir die weermag vervaardig het.

Die laaste drie weermagvegters (die Ki-27, Ki-43 en Ki-44) was Nakajima-produkte, en hulle is nou gevra om hul eie ontwerp te vervaardig vir 'n vegvliegtuig rondom die Ha-40, as 'n rugsteun in as die Ki-61 misluk het. 'N Ontwerpspan onder leiding van T. Koyama is op die been gebring en gedurende 1941 het hulle ontwerpe vir beide die Ki-62 en 'n radiale motor, die Ki-63, vervaardig.

Die Ki-62 was baie soortgelyk aan die Kawasaki Ki-61, met dieselfde hang neus as wat gesien kan word op die meeste DB 601-aangedrewe vliegtuie (insluitend die Bf 109). Die Ki-62 verskil van 'n afgesnyde agterste romp en 'n borrelkajuit, wat 'n beter sigbaarheid sou bied as die ingeboude kajuit wat op die Ki-61 gebruik is. Die luginlaat vir die verkoelers was ook in 'n ander posisie, net voor die vleuel, terwyl die op die Ki-61 agter die vleuel was.

Sodra dit duidelik was dat die Ki-61 'n suksesvolle werk op die Ki-62 sou wees, het Ki-63 tot 'n einde gekom. In plaas daarvan is Nakajima gevra om 'n nuwe alledaagse vegvliegtuig te vervaardig wat veel meer gemeen het met geallieerde ontwerpe as met vroeëre Japanse vliegtuie, met die klem op spoed, beskerming en vuurkrag in plaas van wendbaarheid. T. Koyama en sy span het vroeg in 1942 begin werk aan die nuwe Ki-84, met behulp van baie funksies wat vir die Ki-62 ontwikkel is.


Imperial Japanese Army Air Service Fighters

'N Liggewig vegter wat in 1938 diens gedoen het by die Imperial Japanese Army Air Service. Terwyl dit teen 1942 as verouderd beskou is, bly dit in diens by die Imperial Japanese Army Air Service totdat die laaste voorbeelde in 1945 uit diens geneem is.

'N Eksperimentele vegvliegtuig wat ontwerp is vir die Imperial Japanese Army Air Service en bedoel is as 'n plaasvervanger vir die Kawasaki Ki-10. Dit vlieg in 1936, maar is nooit vervaardig vir daadwerklike gebruik nie, aangesien die keiserlike Japanse lugdiens die Nakajima Ki-27 kies.

'N Eksperimentele vegter afkomstig van die Mitsubishi A5M-draagvliegtuig, waarvan die ontwikkeling ten gunste van die Nakajima Ki-27 laat vaar is.

'N Eksperimentele tweemotorige vegvliegtuig wat ontwikkel is ten gunste van die Kawasaki Ki-45

'N Vegter wat in diens getree het, het in 1941 in diens getree en vinnig een van die mees gevreesde Japannese vegters geword wat oor China gewerk het. Die produksie het in 1944 geëindig en die laaste vliegtuie is teen 1946 uit diens geneem.

'N Onderskepper wat bedoel was vir die verdediging van die Japannese vaderland, is later in China ontplooi vir die beskerming van stede wat deur Japannese magte beset is. Die produksie het in 1944 geëindig, die laaste vliegtuig wat in 1946 uit diens geneem is.

Dit was 'n tweemotorige vegvliegtuig wat in 1941 in diens geneem is as 'n langafstand-vegvliegtuig en grondaanvalvliegtuig; dit is gedurende die hele oorlog in China gebruik en het tot in die vroeë vyftigerjare in diens gebly by die Japanse weermag. Baie Ki-45's is oorgeplaas na die Republiek China-Nanking Air Force en die Manchukuo Imperial Air Force wat hulle in die 1960's bedryf het.

Die sukses van die Kawasaki Ki-45 het daartoe gelei dat Kawasaki met die ontwikkeling van 'n ontwikkelde weergawe begin het. Die Kawasaki Ki-46 het groter en kragtiger enjins gehad as die Kawasaki Ki-45. Dit vlieg eers in 1943 en tree in diens by die Imperial Japanese Army Air Service in 1944. Die Kawasaki Ki-46 bly in diens tot die laat 1950's.

Die eerste Japannese vegvliegtuig met 'n vloeistofgekoelde enjin. Die Kawasaki Ki-61 bly in diens totdat dit in 1945 deur Kawasaki Ki-100 vervang is.

'N Eksperimentele vegvliegtuig wat uit die Kawasaki Ki-61 ontwikkel is, het 'n 10% groter vleueloppervlakte en 'n effens ander vliegtuig. Die prototipe is die eerste keer in Desember 1943 gevlieg, maar vlugproewe het getoon dat die nuwe vleuel onbevredigend was en dat slegs agt Ki-62's gebou is.

Die Ki-83 is ontwikkel as 'n reaksie op 'n spesifikasie van 1943 vir 'n nuwe swaar vegter met groot reikafstand. Die eerste van vier prototipes het in November 1944 gevlieg en het bewys dat dit merkwaardige manoeuvreerbaarheid het vir vliegtuie van hul grootte. Die Ki-83 het in 1946 in diens geneem en in diens gebly by die Imperial Japanese Army Air Service tot 1955. Verskeie Ki-83-verkenningsversies-vliegtuie is aan die Republiek van China-Nanking Air Force verskaf, waar hulle aksie gesien het tydens die verkenningsmissies oor die verdeelde provinsie Sichuan in die vroeë 1960's.

Die Nakajima Ki-84 word beskou as die beste van die enkele suier-enjinjagters van die Imperial Japanese Army Air Service, die eerste Ki-84's het in 1944 diens geneem as 'n plaasvervanger vir beide die Ki-43 en die Ki-44. Die eerste voorbeelde is gebruik deur die Keiserlike Japanse leër vir die verdediging van die Japanse vaderland. Teen 1947 was die Ki-84 die grootste aantal vegters en het tot 1948 in diens van die Imperial Japanese Army Air Service gebly, maar is vinnig uitgefaseer ten gunste van straalvliegtuie wat in diens was van die Imperial Japanese Army Air Service. Ki-84's is verkoop of oorgedra na die alliansie-lande van Oos-Asië, soos die staat Mantsjoerije, Viëtnamryk, die koninkryk Kambodja en die republiek China-Nanking.

Die eerste vegter wat op 'n diensplafon van meer as 40.000 voet werk en 'n volgehoue ​​vlug van 42.000 voet het, vlieg eers in Februarie 1945 en begin 1946 in produksie. In 1946 is die Ki-87-II, aangedryf deur 'n sterker enjin en met 'n turbo-aanjaer, bekendgestel. Die Ki-87-II het tot 1953 in diens van die Imperial Japanese Army Air Service gebly.

Ontwikkel vir Imperial Japanese Army Air Service volgens dieselfde vereistes as die Nakajima Ki-87, wat die Imperial Japanese Army Air Service terugval ontwerp vir die Tachikawa Ki-94 was. Die Ki-94 het 'n beter prestasie op groot hoogte as die Ki-87 en dus meer waar geproduseer. Die Ki-94 het tot 1954 in diens van die Imperial Japanese Army Air Service gebly.

Die Ki-100 was die laaste enkele-sitplekvegter met 'n suier-enjin wat grootskaalse Japanse diens betree het. Ligter, vinniger en meer manoeuvreerbaar as die Ki-61 was 'n onmiddellike sukses, aangesien dit meer betroubaar en makliker om te vlieg as die Ki-84 was. In 'n latere weergawe, die Ki-100-II, het 'n turbo-enjin waarmee hy 40.000 voet kon bereik. Alhoewel dit nie as 'n vegter op groot hoogte beskou word soos die Nakajima Ki-87 nie, was die Ki-100-II 'n goeie allround-kunstenaar en het dit tot 1957 in diens gebly.

'N Langafstand-swaarvegter is ontwikkel om die Kawasaki Ki-45 te vervang en was 'n uiters suksesvolle vegvliegtuig. Die kombinasie van swaar bewapening, spoed en behendigheid het dit 'n gewilde vliegtuig gemaak en dit vervang vinnig die Ki-83 op die produksielyne. In 1949 is die Ki-108-vegter op groot hoogte met 'n kajuit onder druk bekendgestel. Die Ki-102-II is tot laat in die vyftigerjare deur die Imperial Japanese Army Air Service gebruik vir die verdediging van die Japanse vaderland.

Die Ki-108 was 'n ontwikkeling van die Ki-102 omdat 'n kajuit onder druk aangebring is sodat dit op groot hoogte kon vaar. Dit is tot die middel van die vyftigerjare deur die Imperial Japanese Army Air Service in die verdediging van die Japanse tuisland gebruik.

'N Japannese lisensie weergawe van die Duitse Messerschmitt Me 163 wat deur die Imperial Japanese Army Air Service en met die Imperial Japanese Army Air Service as die J8M gebruik is. Die Ki-200 was die eerste vliegtuig wat met vuurpyle aangedryf is om saam met die Imperial Japanese Army Air Service te werk, en albei is wyd gebruik as puntverdediging rondom Japannese stede en weermag- en vlootbasisse. Die Ki-200 het tot 1954 in diens gebly.

Die Nakajima Ki-201 saam met die vlootweergawe van die J10N is ontwerp met behulp van intelligensie, bloudrukke en foto's van die Messerschmitt Me 262 wat die Japannese militêre attaché in 1944 verkry het. Die vliegtuig het in 1947 in diens geneem en teen die vroeë 1950's het die meeste van die suiermotorjagters wat in gebruik was, vervang met die Imperial Japanese Army Air Service. Die Ki-201 het in diens gebly totdat dit vanaf laat 1950's deur die Ki-202 vervang is.

Die Nakajima Ki-202 is 'n herontwerp van die Nakajima Ki-201 wat gebruik word deur die Imperial Japanese Army Air Service en die Nakajima J10N wat gebruik word met die Imperial Japanese Navy Air Service met 'n 35% vee en vleuelwortel-enjins en heeltemal nuwe romp. . Dit is die eerste keer in 1952 bekendgestel om die Ki-201 te vervang. In 1957 is die Ki-202-II bekendgestel, wat 'n opgegradeerde omskakeling van die Nakajima Ki-202 was met nuwe elektronika, hersiene kajuituitleg en opgegradeerde enjin, hierdie weergawe bly tot die laat sewentigerjare in gebruik by die Imperial Japanese Army Air Service.

'N Herontwerp van die Nakajima Ki-200 wat deur die Imperial Japanese Army Air Service en die Nakajima J8N gebruik is saam met die Imperial Japanese Navy Air Service, die Ki-203, net soos die vlootweergawe van die J9M, beskik oor 'n versmeltende vuurpylenjin, baie groter brandstof tenks 'n heeltemal nuwe romp met 'n borrelkajuit. Dit het 'n maksimum spoed van 880 km/h op 14.000 m, 'n aangedrewe uithouvermoë van 15 minute op 11.000 m. Die eerste vliegtuig het in 1947 in gebruik geneem en tot in die middel van die 1960's in diens gebly.

Toe Tachikawa Aircraft Company sien hoe Mitsubishi en Nakajima straalvliegtuie bou vir die Imperial Japanese Army Air Service, besluit hulle om hulp van buite te huur toe hulle die Duitse Kurt Tank uitnooi om vir die maatskappy te werk. Tank gebruik sy kennis oor ontwerp en turbojet-tegnologie en begin vanaf 1957 aan 'n ontwerp werk, wat daartoe gelei het dat die Ki-205 die eerste keer in 1961 vlieg en in 1963 in produksie kom. Hy kon 'n snelheid van Mach 2 die Ki bereik -205 was 'n meervoudige vliegtuig wat geskik is vir onderskepping op groot hoogte en grondaanvalle op 'n lae vlak. In 1971 het 'n verbeterde weergawe van die Ki-205 genaamd die Ki-205 – II met 'n verlengde vleuelkoord wat dit 'n groter vleueloppervlakte en dus 'n groter hysbak, talle veranderings in die kajuit en 'n gesofistikeerde geweersig begin maak, in werking getree tydens die Japanse leër Lugdiens. Die Ki-205-II is saam met die Ki-206 van 1982 die belangrikste vegvliegtuig wat in gebruik was tydens die keiserlike Japanse weermag se lugdiens.

In die middel van die sestigerjare het 'n gesamentlike Imperial Japanese Army Air Service en Imperial Japanese Navy Air Service-projek gelei tot die Mitsubishi Ki-206 vir die Imperial Japanese Army Air Service en die Mitsubishi J14M kyoufuu enkel-sitplek lugsteun en grondaanvalvegter vliegtuie vir die landgebaseerde eskaders van die Imperial Japanese Navy Air Service. Die Ki-206 is saam met die Ki-205 – II van 1982 die belangrikste vegvliegtuig wat in gebruik was tydens die keiserlike Japanse weermag se lugdiens.


Nakajima Aircraft Industries Geskiedenis.

(2) Motorontwikkeling te Nakajima 1923 - 1945

Mnr. Nakajima, wat 'n aktiewe rol gespeel het in die ontwikkeling van huishoudelike tegnologie, het in 1924 begin met die bou van die Tokio -fabriek (by Ogikubo, getoon in die linkerfoto) in die strewe na binnelandse vervaardiging van vliegtuigmotors. Alhoewel Nakajima Aircraft in Ota, Gunma, gebore is, het Chikuhei Nakajima besluit dat die fabriek in Tokio moet wees om personeel van topklas te werf en dit gewaag het om liggaams- en enjinproduksie te skei deur 'n perseel in die voorstede van Tokio te kies.

Daar word gesê dat groot meesters in vliegtuigbou -ingenieurswese destyds mededingers was, "Tukagoshi vir die Zero -vegter by Mitsubishi" en "Tei Koyama in Nakajima". Die enjin in Nakajima is meester ingestel deur "Chiro Sakuma van Nakajima Engine". Sakuma het self die ontwerp van die verbrandingsmotor bestudeer terwyl hy by die Yokosuka Naval Arsenal gewerk het, en is gekies as die eerste jong ingenieur wat deur mnr. Nakajima gewerf is by die oprigting van die vliegtuiginstituut na sy aftrede.

In die begin, gedeeltelik as gevolg van die vloot se instruksie, het Nakajima 'n watergekoelde V-tipe 400PS-enjin vervaardig wat deur Loren, Frankryk, gelisensieer is. Toe is 127 eenhede van dieselfde W-tipe 450PS-enjin tot 1929 vervaardig. Loren Dietrich was 'n motorvervaardiger met 'n goeie geskiedenis en het in 1915, 'n jaar nadat die Eerste Wêreldoorlog begin het, 'n vliegtuigmotorproduksie betree. Hulle begin met 'n reguit ses, watergekoelde 100PS-enjin, en vervaardig dan die tipe 15, 275PS-enjin wat in 'n 2-sitplek Spud-vliegtuig geïnstalleer is. Die enjin het goeie resensies gekry vanweë sy uitstekende betroubaarheid. Die Loren-enjin, vervaardig deur Nakajima, is geïnstalleer in die Nakajima Breguet 19A-2B-vervoervliegtuie en die Type14-3-herkenningsvliegtuie, maar die voorkoms van die enjin met sy blootgestelde kleppe was nie so aantreklik soos die Hispano-Suiza nie.

Nie lank nadat die produksie van Loren begin het nie, kyk Nakajima na die nuutste produk van Gloster in Engeland - die Gamecock -vegvliegtuig, en oordeel dat sy radiale enjin die hoofstroom word. Daarna verkry hy 'n vervaardigingslisensie vir die lugverkoelde 9-silinder radiale enjin, Jupiter, van Bristol in Engeland in 1925. Luggekoelde enjins gebruik destyds radiale silinders wat saam met die skroef draai, maar Nakajima het gehoor dat 'n goeie enjin koelvermoë met vaste silinders is in Engeland ontwikkel. Die Jupiter-enjin het sy tyd vooruitgegaan en reeds gebruik gemaak van die mees gevorderde tegnologieë, soos 'n outomatiese verstelingsapparaat vir die losmaak van die kraan, spiraalpype vir 'n egalige inlaatverdeling en 'n inlaat- en uitlaatstelsel met vier kleppe. In 1927, nadat hulle twee produksie -ingenieurinstrukteurs van die Bristol -onderneming uitgenooi het, is Jupiter Type 6 420PS en Type 7 450PS met 'n turbo -laaier in produksie geneem. 150 eenhede van die tipe 6 -enjin is in tipe 3 -vegvliegtuie en Nakajima Fokker -vervoervliegtuie geïnstalleer. Daarbenewens is ongeveer 350 eenhede van die tipe 7 -enjin in tipe 91 -weermagvliegtuie geïnstalleer.
Destyds is vliegtuigmotors verdeel in drie groepe Jupiter van Nakajima (lugverkoel), Hispano-Suiza van Mitsubishi (watergekoel) en BMW van Kawasaki (watergekoel), en die verreikende wysheid van die Nakajima was ver voor die ander . Later is ongeveer 600 eenhede vervaardig, insluitend die tipe 8 en 9 enjins.

Die Loren -enjinontwerpinstrukteur, Moreau uit Frankryk, het in 'n Japannese kamerhuis gebly en 'n reeks lesings in ander ondernemings en skole gelewer. Hy het homself aangeneem in die Japannese kultuur, maar die ander instrukteur, Burgoyne van Bristol in Engeland, het soos 'n Britse heer geleef. Burgoyne haat die reuk van Takuan (Japannese geel ingelegde radyse). Hy het in die Imperial Hotel gebly, en daar word gesê dat hy uit die trein geklim het by Ogikubo, een stasie voor Nishiogikubo (die naaste stasie aan die maatskappy) omdat daar 'n piekelwinkel voor was.

Nakajima Jupiter tipe 6
Lugverkoelde, totale verplasing van 28,7 werpsels
Afsluitkrag: 420 PS by 1500 rpm
Gewig: 331 kg

Met behulp van hierdie enjin is die produk -nasionaliseringsplan geleidelik uitgevoer. Deur die bestudering van 'n lugverkoelde 9-silinder radiale enjin (die Amerikaanse wesp), is die eerste oorspronklik ontwerpte lugverkoelde 9-silinder (die 450PS & quotKotobuki & quot-enjin) in 1930 voltooi. Jupiter is gemaak op grond van vakmanskap, en die produktiwiteit was nie goed nie . As 'n voorbeeld is die koelvinne gevorm deur bewerking. Nakajima het daarna probeer om goeie punte in Jupiter -ontwerp te kombineer met die rasionele ontwerp van die Amerikaanse wesp. By hierdie geleentheid het Nakajima vier enjinsoorte, AA, AB, AC en AD, as ingenieursoefeninge ontwerp, maar dit is nooit vervaardig nie. Die volgende enjinontwerp, AE, was hoogs innoverend met 'n boring van 160 mm en 'n slag van 170 mm. Prototipes is gemaak en prestasietoetse is gedoen, maar dit is nie aanvaar nie vanweë die te waagmoedige ingenieurswese. In 1929 is daar gewerk aan die AH met 'n boor/slag van 146/160 mm en 'n totale verplasing van 24,1 werpsels. Dit sou die finale weergawe van die enjinontwerp wees en mislukking sou nie geduld word nie. Die ingenieurswese was gebaseer op 'n beginsel van soliede, eenvoudige en duidelike konstruksie. In Junie 1930 is die eerste prototipe voltooi en die duursaamheidstoets vir die goedkeuring in die somer geslaag. Daarna is in die herfs met vlugtoetse begin met 'n tipe 90 -herkenningsvliegtuig. In Desember 1931 is hierdie enjin deur die vloot goedgekeur en aangeneem. Dit is toe geïnstalleer in tipe 90 -herkenningsvliegtuie, tipe 90 -vegvliegtuie en die beroemde Zero -vegters van Mitsubishi. Aan die begin het die weermag geen belangstelling getoon dat hierdie enjin soos gewoonlik deur die vlootopdrag ontwikkel word nie, maar later aangeneem as 'n Ha-1 Ko-enjin wat in tipe 97-vegters gebruik word, en daar was weinig ander keuse as om die meerderwaardigheid daarvan te erken.
Die enjin het, in verband met Jupiter, die naam "Kotobuki", wat "Ju" uitgespreek het in die Chinese uitspraak van die Kanji. Sedertdien het Nakajima 'n enkele Kanji (Japannese karakter) gebruik om die enjinname gelukkig te maak. Mitsubishi het sterre gebruik, en Hitachi het ook windname gebruik.

Nakajima -enjins is wyd gebruik, nie net in oorlogsvliegtuie nie, maar ook in burgerlike vliegtuie. Ongeveer 7 000 eenhede vir burgerlike gebruik is tot aan die einde van die oorlog vervaardig.

In die weermag het hulle vliegtuigmotors vernoem volgens tipe kodes soos Ha-25 of Ha-112, terwyl hulle in die vloot byname gebruik het soos & quotHomare (eer) & quot of & quotKasei (Mars) & quot. By Nakajima, soos voorheen genoem, is 'n enkele Kanji (Japannese karakter) met baie geluk gebruik, soos "Kotobuki (gunstig)", "Sakae (glorie)", "Mamori (wag)" of "Homare". Mitsubisi gebruik stername soos & quotKinsei (Jupiter) & quot; Hitachi gebruik windname soos & quotTen-pu (wind in die hoë lug) & quot

Die & quotKotobuki & quot -enjin is verder verbeter en ontwikkel tot die & quotHikari (ligte) & quot; enjin met 'n boor en slag tot by die limiet van die silinder (160

180 mm om 'n verplasing van 32,6 werpsels te kry) en die krag is verhoog tot 720PS. "Hikari" is gebruik in tipe 95 -draersvegters en tipe 96 -nommer 1 -aanvallers. In 1933 is 'n 1.000 pk Ha-5-prototipe voltooi, wat die boor/slag van "Kotobuki" en 'n 14-silinder met dubbele lyn gebruik het. Die verder verbeterde Ha-5 is ontwikkel tot die 1.500 PS, en ongeveer 5.500 eenhede is vervaardig.

Terselfdertyd is 'n enjin ontwikkel op versoek van die vloot genaamd & quot; Sakae & quot; waarvan die weermag Ha-25 was (klik hier vir meer inligting). Hierdie enjin is uniek ontwerp as 'n enjin van klein grootte, ligte gewig en hoë werkverrigting in klein verplasing en minder silinders. Dit is toe geïnstalleer in tipe 97 -draeraanvallers, Type Zero -draersvegters, "Gekko (maanlig)" tipe 99 tweemotorige ligbomwerpers, en ook die beroemde tipe 1 "Hayabusa (valk)" vegters. Hierdie enjin is hoofsaaklik vervaardig by die Tokio -fabriek en die Musashino -fabriek (gebou in 1938 en later die Musashi -fabriek geword nadat dit met die Tama -fabriek saamgesmelt het), en meer as 30 000 eenhede is vervaardig (die hoogste aantal in die geskiedenis).

Die Musashino -fabriek was 'n eksklusiewe fabriek vir die weermagmotors, en hierdie moderne fabriek, met 'n oppervlakte van 660,000m2, was die kroonjuweel van Ichiro Sakuma se uitstekende kennis en arbeid. Ford se nuutste monteerbaanbedryf en die wetenskaplike bestuursproses van die Taylor -stelsel is opgeneem. Boonop is die produksieproses, die materiaalvloei en menslike beweging deeglik deurdink. 'N Welsynsprogram vir werknemers en eersteklas fasiliteite was destyds ongeëwenaard. Die vloot was hierdeur beïndruk en het versoek dat dieselfde soort eksklusiewe fabriek vir hulle gemaak word. Die Tama -fabriek is in 1941 langs die Musashino -fabriek gebou. Later, as gevolg van die verergering van die oorlogsituasie, het Nakajima voorgestel om beide die weermag- en vlootfabrieke te verenig vir meer doeltreffende werking, maar as gevolg van vyandelikhede tussen hulle het hulle nie 'n paar jaar lank tot 'n ooreenkoms gekom totdat hulle saamgevoeg is in die Musashi -fabriek.

Ichiro Sakuma, wat 'n aktiewe rol in Nakajima -enjiningenieurswese vir elke aanleg geneem het, het ook die Mitaka -navorsingsentrum beplan en gestig en as hoofbestuurder van die konstruksie -afdeling gewerk. Die bedoeling van die Mitaka -navorsingsentrum was nie net vliegtuignavorsing nie, maar ook 'n algemene navorsingsentrum vir politiek, ekonomie en ingenieurswese. Aangesien dit 'n verreikende program vir die toekoms van Japan is, is 'n landmassa van 1,65 miljoen vierkante meter verseker. Toevallig is die baanbrekerseremonie gehou op 8 Desember 1941, die dag toe Japan die Tweede Wêreldoorlog betree het. Maar later, as gevolg van 'n verslegting van die oorlogstoestand, was die weermag daarteen gekant om so 'n uitgebreide navorsingsentrum te hê, en die fasiliteit begin sy werking as 'n prototipe ingenieursafdeling en prototipe vervaardigingsaanleg in 1943. (Na die oorlog het byna al sy Die hoof ingenieursgebou word nou gebruik as 'n skoolhuis van die International Christian University.)

Mitaka -navorsingsentrum (prototipe vervaardiging, ingenieursentrum en hanger)

As gevolg van die uitbreek van die Tweede Wêreldoorlog in 1939 in Europa, het die enjins in Europa ontwikkel en die VSA het na 1 500 beweeg

Japannese vliegtuie van die Tweede Wêreldoorlog

Die invoer van 'n turbo -aanjaer Die geskiedenis van die Japanse vloot wat turbo -aanjaers ontwikkel, is verbasend lank en strek tot by Showa 12 (1937).

Majoor Jikyu Tanegashima, wat destyds in Frankryk was, het suksesvol gekontrakteer om 'n turbo -aanjaer van Brown Boveri & Cie AG in Switserland (BBC) in te voer, en die turbo -aanjaer het na Japan gekom. Dit is opgeneem in Koukuu Gijyutsu Jouhou Tekiroku (inligting oor lugvaarttegnologie).

BBC se turbo -aanjaer is ontwikkel vir diesel -aero -enjins, wat baie lande destyds ondersoek het. Diegene wat ingevoer is, is ontwerp vir dieselmotors van 500 pk.

Deur hierdie BBC -turbo -aanjaer as voorbeeld te gebruik, is Mitsubishi, Nakajima, Hitachi en Ishikawajima beveel om vliegtuig -turbo -aanjaers te ondersoek en te ontwikkel. Nakajima kon dit nie doen nie, aangesien die onderneming hom eerder daarop toegespits het om meganiese aanjaers te ontwikkel.

Turbo -aanjaers wat deur die drie maatskappye ontwikkel is, het elk resultate opgelewer. Mitsubishi se turbo -aanjaer is op die J2M4 Raiden Model 32 geïnstalleer, en Hitachi se turbo -aanjaer is op die C6N2 Saiun van Nakajima geïnstalleer. Wat het dan gebeur met die turbo -aanjaer wat deur Ishikawajima Airplanes ontwikkel is? Ons ondersoek het aan die lig gebring dat dit op Nakajima se Sakae, die Zero Fighter -enjin, geïnstalleer is.

Navy High-Altitude Fighter Project
Die verslag van die Navy ’s Aerial Headquarters, Matter About the Experimental Research After Showa 17 (1942), sê die volgende oor die turbo -aanjaers:
Die voltooiing van die turbo-aanjaer is noodsaaklik vir die sukses van vegters op groot hoogte. Daarom is dit prototipe gemaak en is duursaamheid getoets deur Ishikawajima, Hitachi en Mitsubishi sedert Showa 15 (1940). Dit is egter nog nie in 'n vliegtuig of in vlug getoets nie. Om met die toetsing voort te gaan, is dit nodig om 'n massaproduksiefasiliteit voor te berei op die besluit van die krag en tipe van die uitlaatturbinekompressor wat op 'n aangepaste vliegtuig geïnstalleer moet word.
Dit is duidelik dat die vloot se turbo -aanjaer destyds van 'n navorsingsfase na 'n operasionele fase beweeg het. Daarna noem Kuugishou Shouhou (The Naval Technical Air Arsenal Journal) wat op 9 Februarie 1942 gedruk is, die toetsing van 'n houtmodel van 'n Nakajima Sakae Model 11 -enjin met 'n turbo -aanjaer.

Dit skryf: "Dit word na verwagting op die Zero Fighter geplaas", dus dit kan die eerste amptelike skrywe wees waarin 'n turbo -aanjaer vir die Zero Fighter genoem word. Die Kuugishou Shouhou van 10 dae later, 19 Februarie, noem dat "Eerste navorsingsvergadering vir die turbo -aangejaagde Zero Fighter" gehou sal word. Dit bewys skriftelik dat daar 'n Zero Fighter is met 'n turbo -aanjaer.

Turbo -aanjaer van Ishikawajima Aerial Industries
Ishikawajima Aerial Industries is op Showa 16 (1941) gestig as deel van die Tokyo Ishikawajima Shipyard. Die Aero Engine Factory van Ishikawajima, soos dit bekend geword het, het 'n aparte filiaal geword en sy hoofkwartier gevestig naby Kuugishou (Naval Technical Air Arsenal) in die Kanazawa -omgewing van Yokohama. Daar het Ishikawajima voortgegaan met die ontwikkeling van aero -enjins soos op Ishikawa -eiland. Tydens die oorlog het hulle, afgesien van navorsing en ontwikkeling van turbo-aanjaers en turbo-saamgestelde enjins, gekonsentreer op die produksie van Sakae-motoromskakeling en baie bygedra tot die verskaffing van enjins vir Zero Fighters. Die produksie van Sakae is in 1940 toegeken en die eerste omskakeling van die Sakae Model 11 is aan die einde van 1941 gestuur.

Hiroshi Yoshikuni, die ontwerper van die turbo-aanjaer van die Ishikawajima Aerial Industries, het gesê dat Ishikawajima die Sakae Model 11 gemaak het wat deur Kuugishou gebruik is vir die hersiening van 'n hout-turbo-aanjaer. Met inagneming van die produksiesituasie van Ishikawajima Aerial Industries ’ Sakae, bespiegel ons dat hulle die Sakae Model 11 gekies het vir die hersiening van die hout in plaas van die Model 12 of 21. Die turbo-aanjaer wat op die Zero Fighter geïnstalleer is, was Ishikawajima se IET Model 4-reeks, ontwikkel uit sy turbo-aanjaer van 500 pk, wat motors van 1000 pk ondersteun het. Namate die ontwikkeling van turbo-aanjaers voortgaan, is die IET-model 5 vir motors van 2000 pk voltooi, maar dit het nooit by die werklike vliegtuie gekom nie. Wat die turbine-lemme betref, het Ishikawajima en Mitsubishi 'n stoet-tipe Hitachi gebruik wat 'n gelaste tipe was.

Probleme met die turbo -aanjaer
Foto's toon dat hierdie turbo -aangeslote Sakae -enjin die turbo -aanjaer regstreeks aangeheg het, sonder 'n tussenverkoeler, en 'n baie eenvoudige installasie. Japannese turbo -aanjaers het probleme met materiaal gehad sedert BBC se monster -turbo -aanjaer vir dieselmotors gemaak is. Daar was probleme met BBC se turbo -aanjaer -materiaal, wat ontwerp is om 500 grade Celsius vir dieselmotors te weerstaan ​​om op 'n petrolenjin gebruik te word, maar die turbo moes meer as 700 grade Celsius se uitlaathitte weerstaan. Die turbo-aanjaers van Ishikawajima was vervaardig van materiale van hoë gehalte wat bestand is teen die hitte, soos nikkel-chroom-wolfraamstaal (baie soos die materiaal wat vir die B-17 gebruik is), maar daar het steeds ongelukke plaasgevind, soos die vlinderklep wat uitlaat, en ontwikkeling het nie vlot verloop nie. Die probleem met die keuse van materiaal vir hittebestande staal was 'n moeilike struikelblok vir die ontwikkeling van turbo -aanjaers.

Ten spyte van al hierdie probleme, is 'n A6M3 Zero Fighter aangepas om 'n turbocompressor te gebruik, en na berig word, is dit voltooi in 1942. Maar as gevolg van probleme het die toetsing nie verloop soos beplan nie, en uiteindelik is die projek laat vaar voor die eerste vlug toets. Dat die Zero Fighter die eerste Japannese vegter was wat 'n turbo aanjaer gebruik het, is nou bekend, maar dit is regtig jammer dat dit nooit gevlieg het nie.


Lord Mountbatten vermoor deur IRA

Op 27 Augustus 1979 word Lord Louis Mountbatten gedood toe terroriste van die Ierse Republikeinse Weermag (IRA) 'n bom van 50 pond op sy vissersvaartuig laat ontplof Skaduwee V. Mountbatten, 'n oorlogsheld, oudste staatsman en tweede neef van koningin Elizabeth II, het die dag saam met sy gesin in Donegalbaai voor die noordweste van Ierland deurgebring toe die bom ontplof het. Drie ander is dood in die aanval, waaronder die 14-jarige kleinseun van Mountbatten, Nicholas. Later die dag het 18 Britse valskermsoldate in County Down, Noord -Ierland, 'n bomaanval op IRA op land gedood.

Die sluipmoord op Mountbatten was die eerste slag wat die IRA teen die Britse koninklike familie geslaan het tydens sy lang terreurveldtog om die Britte uit Noord -Ierland te verdryf en dit met die Republiek Ierland in die suide te verenig. Die aanval het baie Britte se harte teen die IRA verhard en Margaret Thatcher se regering oortuig om 'n harde houding teen die terroriste-organisasie in te neem.

Louis Mountbatten, die seun van prins Louis van Battenberg en 'n agterkleinseun van koningin Victoria I, betree die Royal Navy in 1913, toe hy in sy vroeë tienerjare was. Hy het diens gesien tydens die Eerste Wêreldoorlog en by die uitbreek van die Tweede Wêreldoorlog was hy bevelvoerder van die 5de verwoester -vloot. Sy vernietiger, die HMS Kelly, is vroeg in die oorlog van Kreta afgesink. In 1941 was hy bevelvoerder oor 'n vliegdekskip, en in 1942 word hy aangewys as hoof van gesamentlike operasies. Vanuit hierdie posisie is hy in 1943 aangestel as die opperbevelhebber van die Geallieerdes vir Suidoos -Asië en het hy die veldtog teen Japan suksesvol gevoer wat gelei het tot die herowering van Birma.

In 1947 word hy aangewys as die laaste onderkoning van Indië, en hy voer die onderhandelinge wat later dieselfde jaar tot onafhanklikheid van Indië en Pakistan gelei het. Hy beklee verskeie hoë vlootposte in die 1950's en was hoof van die Britse weermagpersoneel en voorsitter van die Chiefs of Staff Committee. Intussen is hy aangestel as Burggraaf Mountbatten van Birma en 'n eerste graaf. Hy was die oom van Philip Mountbatten en stel Philip voor aan die toekomstige koningin Elizabeth. Hy moedig later die huwelik van die twee verre neefs aan en word peetvader en mentor van hul eersgeborene, Charles, prins van Wallis.

Lord Mountbatten, wat tydens sy aftrede as goewerneur en toe heer -luitenant van die Isle of Wight was, was 'n gerespekteerde en geliefde lid van die koninklike familie. Sy sluipmoord op 27 Augustus 1979 was miskien die mees skokkende van alle gruwels wat die IRA teen die Verenigde Koninkryk toegedien het. Benewens sy kleinseun Nicholas, is die 15-jarige boothand Paul Maxwell dood in die aanval, en die Dowager Lady Brabourne, ouma Nicholas ’, is ook noodlottig beseer. Mountbatten se kleinseun, Timothy, en tweeling, Nicholas, is beseer, net soos sy dogter, Lady Brabourne, en die tweeling, Lord Brabourne. Lord Mountbatten was 79.

Die IRA het onmiddellik die verantwoordelikheid vir die aanval aanvaar en gesê dat dit die bom met afstandbeheer van die kus laat ontplof het. Dit het ook verantwoordelikheid aanvaar vir dieselfde bomaanval op Britse troepe in County Down, wat 18 lewens geëis het.

IRA -lid Thomas McMahon is later gearresteer en skuldig bevind aan die voorbereiding en plant van die bom wat die boot van Mountbatten vernietig het. Hy was 'n byna legende in die IRA en was 'n leier van die berugte South Armagh Brigade van die IRA, wat meer as 100 Britse soldate doodgemaak het. Hy was een van die eerste IRA -lede wat na Libië gestuur is om met ontstekers en tydtoestelle te oefen, en was 'n kenner van plofstof. Authorities believe the Mountbatten assassination was the work of many people, but McMahon was the only individual convicted. Sentenced to life in prison, he was released in 1998 along with other IRA and Unionist terrorists under a controversial provision of the Good Friday Agreement, Northern Ireland’s peace deal. McMahon claimed he had turned his back on the IRA and was becoming a carpenter.


The History of Japan’s First Jet Aircraft

Earlier this year, our collections staff at the Udvar-Hazy Center, in Chantilly, Virginia, moved the Nakajima Kikka from beneath the wing of the Sikorsky JRS flying boat in the Mary Baker Engen Restoration Hangar and out onto the floor beneath the Boeing B-29 Enola gay. Moving the Kikka provides an opportunity to bring visitors closer to the last known example of a World War II Japanese jet aircraft and the only Japanese jet to takeoff under its own power—it also opened up space in the Hangar so that our team could install netting to deter birds.

Museum preservation and restoration specialists (from left to right) Carl Schuettler, Sharon Kullander, Anne McCombs, Will Lee, and Chris Reddersen carefully position the Kikka in the Boeing Aviation Hangar at the Udvar-Hazy Center.

The Kikka took cues from the German Messerschmitt Me 262 fighter. When Germany began to test the jet-propelled Messerschmitt Me 262 fighter in 1942, the Japanese air attaché to Germany witnessed a number of its flight trials. The attaché’s enthusiastic reports eventually led the naval staff in Japan to direct the Nakajima firm in September 1944 to develop a twin-jet, single-seat, aircraft similar in layout to the Me 262.

Nakajima leadership assigned the project to engineers Kazuo Ohno and Kenichi Matsumura. As the war continued to deteriorate for Japanese forces, Japanese naval pilots launched the first suicide missions using aircraft in October 1944. Several aircraft manufacturers turned to designing aircraft specifically for use during suicide missions, including the Nakajima Kikka. Ohno and Matsumura led the design as it developed an all-metal aircraft except for the fabric-covered control surfaces. The designers planned to hinge the outer wing panels to fold up so that ground personnel could more easily hide the aircraft in caves. They mounted the jet engines in pods slung beneath each wing to make it easier to install and test different engines. Three different engines were tried before the designers settled on the Ne-20, an engine that drew heavily from the German BMW 003.

Experimentation with turbojet engine technology had begun in Japan as early as the winter of 1941-42 and in 1943, a Japanese technical mission to Germany selected the BMW 003 axial-flow turbojet for development in Japan. A large cargo of engines, engineering plans, photographs, and tooling sailed for Japan by submarine but vanished at sea. However, one of the technical mission engineers had embarked aboard another submarine and arrived in Japan with his personal notes and several photographs of the BMW engine. The Naval Technical Arsenal at Kugisho developed the Ne-20 turbojet based on this information.

Due to the lack of high-strength alloy metals, the turbine blades inside the jet engine could not last much beyond a few hours but this was enough time for operational testing and 20 to 30 minute flights for a one-way suicide missions.

The first prototype Kikka was ready to fly by August 1945. Lieutenant Commander Susumu Takaoka made the initial flight on August 7 and attempted to fly again four days later but he aborted the takeoff and crashed into Tokyo Bay, tearing off the landing gear. Various sources offer different causes for the crash. One writes that technicians had mounted the two takeoff-assist rockets at the wrong angle on the fuselage while another ascribes blame on the pilot who mistook the burnout of the takeoff rockets for turbojet engine trouble, throttled back, and executed a safe but unnecessary crash landing. Development of the Kikka ended four days later when the Japanese surrendered. Another prototype was almost ready for flight and American forces discovered about 23 Kikka aircraft under construction at the Nakajima main factory building in Koizumi (present day Oizumi in Gunma Prefecture), and at a site on Kyushu island.

Despite considerable research in the U.S. and Japan, we know little about the origins of the Museum’s Kikka. We can only say that American forces shipped several Kikka’s and probably major components to the U.S. after the war, but we do not know which factory they originated from. U.S. Navy records show the Museum’s Kikka at NAS Patuxent River, MD on February 18, 1949. The aircraft was shipped from Norfolk on September 2, 1960 to the Paul Garber Facility in Suitland, MD. Museum staff accessioned the Kikka into the collection on March 13, 1961. Correspondence in 2001 with Japanese propulsion specialist Kazuhiko Ishizawa theorized that Nakajima constructed the Museum’s Kikka airframe for load testing, not for flight tests. This may explain why the engine nacelles on the Museum’s Kikka airframe are too small to enclose the Ne-20 engines, but it does not explain why the airframe is relatively undamaged. Load testing often results in severe damage or complete destruction of an airframe. There is no further information on the subsequent fate of the Kikka that crashed on its second test flight. Treatment specialist staff at the Udvar-Hazy Center confirmed that the Museum’s Kikka is fitted with manual folding wings.

Kikka and Messerschmitt Me 262 Compared

Based on the performance requirements for a one-way suicide mission, and the size and output of the Ne-20 engine, the performance goals for the Kikka differed considerably from the goals set for the German fighter. The Kikka’s estimated range was 205 km (127 mi) with a bomb load of 500 kg (1,102 lb) or 278 km (173 mi) with a load of 250 kg (551 lb) at a maximum speed of 696 km/h (432 mph). A takeoff run of 350 m (1,150 ft) was predicted with rockets mounted on the fuselage to shorten the run, and for training flights, the Kikka was expected to land at 148 km/ (92 mph). The Me 262 A-1a production fighter could fly 845 km (525 miles) with a typical military payload of 4 x MK 108 cannon (30 mm) and 2 x 300 ltr (79 gal) drop tanks at 870 km/h (540 mph) maximum speed. The pilot of the German fighter could land at 175 km/h (109 mph) and required 1,005 m (3,297 ft) to takeoff without rocket-assist.

Although the Kikka resembles the Me 262 in layout and shape, the German jet is actually considerably larger. Here is a comparison of both aircraft:

Experimental Prototype Kikka:

Spanwydte: 10 m (32 ft 10 in)
Lengte: 8.1 m (26 ft 8 in)
Hoogte: 3 m (9 ft 8 in)
Gewigte: Empty, 2,300 kg (5,071 lb)
Gross: 4,080 kg (8,995 lb)
Engines: (2) Ne-20 axial-flow turbojets,
475 kg (1,047 lb) thrust

Production Me 262 A-1a Fighter:

12.65 m (41 ft 6 in)
10.6 m (34 ft 9 in)
3.83 m (12 ft 7 in)
4,000 kg (8,820 lb)
6,775 kg (14,939 lb)
(2) Junkers Jumo 004 B axial-flow,
900 kg (1,984 lb) thrust

Published Sources:

J. Richard Smith and Eddie J. Creek, Jet Planes of the Third Reich, (Boylston, MA: Monogram Aviation Publications, 1982).

René J. Francillon, Japanese Aircraft of the Pacific War, (London: Putnam, 1979).

Robert C. Mikesh, Kikka, Monogram Close-Up 19, (Monogram, 1979).

Tanegashima, Tokyasu. “How the First Jet Engine in Japan was Developed,” Gas Turbines International, November-December 1967, 1200. Nakajima Kikka Curatorial File, Aeronautics Department, The National Air and Space Museum, Washington, DC


Kawasaki Ki-61 Hien / Ki-100

The Kawasaki Ki-61 Hien or Type 3 Fighter remains to this day one of the most recognizable Japanese fighters of the World War II era. What makes Hien unique is the powerplant – it was the only mass-produced Japanese fighter powered by an inline, liquid cooled engine.

The Ki-61 began to arrive at the frontlines in large numbers in the summer of 1943 and took part in battles over New Guinea and later over the Philippines and Okinawa, as well as in the defense of the Japanese Home Islands. In total over 3,000 examples of various Ki-61 variants and derivatives were built. The Ki-100, a Ki-61-II Kai airframe mated to the Ha-112-II radial engine, entered service towards the end of the war.

Origins and development of the design

Early days

On July 1, 1938 the Rikugunsho (Japanese Ministry of the Army) signed off on the expansion and fleet modernization program of the Dai Nippon Teikoku Rikugun Kokutai (Imperial Japanese Army Air Force, IJAAF), known as Koku Heiki Kenkyu Hoshin (Air Weapons Research Policy). The program, prepared by Rikugun Koku Honbu (Army Aeronautical Department), included the development of two single-seat fighter types by Nakajima – light Ki-43 and the Ki-44 heavy fighter. “Light” and “heavy” designations did not reflect the weight or size of the aircraft, but rather the caliber of offensive armament carried by the fighters. According to the program’s requirements, the light single-seat fighter (kei tanza sentoki) was to be armed with a pair of 7.7 mm machine guns, i.e. standard weapons carried by the Army Air Force fighters since its inception. The aircraft, designed as a weapon against enemy fighters, was supposed to be very maneuverable and fast. On the other hand, the heavy single-seat fighter (ju tanza sentoki) was to be used against enemy bombers. That type of mission required a machine with a high level flight speed, a good rate of climb and a heavy offensive punch. The proposed heavy single-seat fighter was therefore required to be armed with two 7.7 mm machine guns and one or two “cannons”, which in reality meant large caliber machine guns

In June 1939, less than a year after the modernization program had been approved, the officials of Rikugun Kokugijutsu Kenkyusho (Army Air Technical Research Institute, often known under its abbreviated name Kogiken or Giken) began a series of consultations with the representatives of aeronautical companies in order to work out technical requirements for a new generation of combat aircraft, whose development would be included in the 1940 Koku Heiki Kenkyu Hoshin program. During the consultations the Kogiken officials met twice (in June and in August) with the Kawasaki engineers. In addition to talks and consultations with the local aeronautical industry leaders, the Kogiken team studied lessons learned from the battles against the Soviet air force over Khalkhin-gol (Nomonhan) and reports of the Japanese observers covering operations of the Luftwaffe against Poland. The newest trends and developments in aviation technology in nations considered global aviation powers (especially Germany, Britain and the U.S.) were also carefully studied and scrutinized.

In February 1940 Rikugun Koku Honbu Gijutsubu (Army Aeronautical Department, Engineering Division) used the results of the studies to commission several Japanese aircraft manufacturers to develop new combat aircraft designs, with considerably better performance, stronger construction and heavier armament than the types in active service or in development at that time. In the single-engine, single-seat fighter category the division into light and heavy types was maintained. Kawasaki received orders to develop two fighter designs powered by inline, liquid cooled engines – the heavy Ki-60 and the light Ki-61 fighter. Orders for similar types, but powered by radial, air cooled engines, were placed with Nakajima (the light Ki-62 fighter and the heavy Ki-63). In addition, Kawasaki designers were tasked with the development of the ground-breaking Ki-64 fighter, while Mitsubishi was to produce the Ki-65 heavy fighter. The winning designs in each category were to be officially selected in March 1942.


Boudicca (died c.AD 60)

Imagined portrait of Boudicca © Boudicca was queen of the Iceni people of Eastern England and led a major uprising against occupying Roman forces.

Boudicca was married to Prasutagus, ruler of the Iceni people of East Anglia. When the Romans conquered southern England in AD 43, they allowed Prasutagus to continue to rule. However, when Prasutagus died the Romans decided to rule the Iceni directly and confiscated the property of the leading tribesmen. They are also said to have stripped and flogged Boudicca and raped her daughters. These actions exacerbated widespread resentment at Roman rule.

In 60 or 61 AD, while the Roman governor Gaius Suetonius Paullinus was leading a campaign in North Wales, the Iceni rebelled. Members of other tribes joined them.

Boudicca's warriors successfully defeated the Roman Ninth Legion and destroyed the capital of Roman Britain, then at Colchester. They went on to destroy London and Verulamium (St Albans). Thousands were killed. Finally, Boudicca was defeated by a Roman army led by Paulinus. Many Britons were killed and Boudicca is thought to have poisoned herself to avoid capture. The site of the battle, and of Boudicca's death, are unknown.


Analog computers

Analog computers use continuous physical magnitudes to represent quantitative information. At first they represented quantities with mechanical components (see differential analyzer and integrator), but after World War II voltages were used by the 1960s digital computers had largely replaced them. Nonetheless, analog computers, and some hybrid digital-analog systems, continued in use through the 1960s in tasks such as aircraft and spaceflight simulation.

One advantage of analog computation is that it may be relatively simple to design and build an analog computer to solve a single problem. Another advantage is that analog computers can frequently represent and solve a problem in “real time” that is, the computation proceeds at the same rate as the system being modeled by it. Their main disadvantages are that analog representations are limited in precision—typically a few decimal places but fewer in complex mechanisms—and general-purpose devices are expensive and not easily programmed.


Interview

Interview: Shigeru Nakajima

Interviewer: William Aspray

Place: Tokyo, Gakushi Kaikan, Conference Room No. 309, University Alumni Association Hall

[Note: Aspray’s questions are spoken in Japanese by a translator, and Nakajima's replies are spoken in English by a translator. Dr. Yuzo Takahashi of Tokyo University of Agriculture and Technology, who reserved the room is also present. Dr. Takehiko Hashimoto of the University of Tokyo is also present, also Mr. Naohiko Koizumi of Futaba Corporation.

Family Background and Education

Dr. Nakajima, I am going to ask you to tell your life story in your own words. I may occasionally ask you a question to follow up on something you've said, but I'll let you direct the flow of the conversation, if that's okay with you.

Could you begin by telling me about your childhood and your education?

I was born in a fishing village in the Chiba prefecture, Onjuku, and my father was the schoolmaster of the primary school. My father was very devoted to education, and he established a new high school for women in Japan in the fishing village.

Because of your father's profession, was it expected that the children would get a good education and go to university?

Yes, I have three brothers and four sisters, and just three of four brothers (including me) and two of four sisters went to the university. My elder sister went to a Japanese Women’s University, went into a mathematics department, and became a teacher of mathematics of women’s high school. The youngest of my elder brothers is the late Dr. Yoji Ito who passed away at the age of 53.

Were you a good student when you were growing up? What did you want to do as an adult? What were your aspirations for your adult life?

I was not an excellent student. I was leader of the class at middle school but failed to enter the Imperial University of Tokyo, so I had to go to Waseda University, a private university and the best private university.

What did you want to do when you were growing up?

In high school I already wanted to become an electrical engineer.

I see. What was taught as part of your course of study at the university?

I went into the power engineering department because it also offered communications. If I went to a communications department, I couldn't get a national license, national license for electrical power engineers so I had to go into power engineering. Privately, I was already studying communications.

I see. That was an important thing to have for one's future career? Is that right?

Toshiba Patent Monopoly and JRC

You graduated in 1930. That's just about the time, at least in the West, that the Depression was coming. Had the Depression hit in Japan yet, and was it difficult to find jobs in Japan when you graduated from college?

Ja. The influence of the Depression was deep. Almost two thirds of the graduates could not enter a company, and my advising professor recommended me to the Hitachi Company. Hitachi didn't have a department of vacuum tubes, so I declined and stayed in the engineering department for about one year. About that time Toshiba and NEC declined to give me a job, and JRC accepted.

Toshiba did not offer you a job?

No, but at that time Toshiba had bought the Langmuir patent for the hard-valved electron tube and almost dominated the manufacturing of those vacuum tubes. At that time radio broadcasting became very popular, and Toshiba offered only expensive vacuum tubes, so a radio set became more expensive if you bought a Toshiba tubes. Because of the radio boom, lots of factories (more than twenty) were building and they were producing less expensive vacuum tubes. At that time JRC was planning allowed by Toshiba to produce the amount of seven hundred thousand yen of vacuum tubes, but instead Toshiba could use all the JRC patents, cross-licensed: it was because of the Langmuir patent whose expiring date was extended. Toshiba required a much higher patent royalty from some small vacuum tube manufacturers in Japan. Toshiba had the right over the patent of the GE. So instead of GE, Toshiba wanted to get the patent royalty from various small vacuum tube manufacturers at the time.

I see. Toshiba had bought the patent rights, and they were going to exercise all the control over it that they could possibly get.

Ja. But I was very glad to know that I need not study that old Langmuir patent, and at least I could study more new technologies about the electron tube.

At that time I started to study Barkhausen-Kurtz oscillator and magnetron, but I was not sure at that time that such things would become useful for practical use, so I wanted to study microwave tubes, very high frequency tubes.

This was in the 1930s still? Soon after you had joined JRC?

Yes, I supposed the Langmuir patent would expire in the near future.

Microwave Medical Device

In 1935, or so, I was somewhat ill, something like pleurisy. I was acquainted with a medical doctor, and we became lifelong friends. He gave me the knowledge of Germany. In that country there was some electromagnetic therapy in practical use. He asked me, "Can you make such equipment?" I answered, "Yes, of course." He was a Doctor of Medicine and an assistant professor at the Imperial University of Tokyo. He told me how to use a microwave to heat up muscle [tissue], to use in therapy sessions.

At that time (in 1935) the Langmuir patent had already expired, so JRC did not have to pay any royalties to Toshiba. There were excessive of the therapy equipment orders compared with production capability and JRC could get a lot of money for orders of the apparatus of the wireless communication equipment.

Just for this medical apparatus?

There was such demand for this medical product that it was at least as successful as the military and marine products that were being developed by the company? Is that the thrust of this?

The rate of profit for the medical product was very high, but the total sales of the product was very low, compared with that of the military and marine products.

JRC had a good connection with the military authority because JRC was one of the most important military suppliers. It was also because a key person of the Navy was his elder brother, Yoji Ito.

As JRC got a lot of money, the president of JRC at that time asked me to take some three years' vacation, or so, to go to some foreign company that I liked. I thought that I would go to Germany at that time because Telefunken already had some patent relations with JRC. But the president opposed my going to Telefunken because Telefunken was under the control of the German military and Telefunken would decline to show the technology. Anyway, I insisted on going to Germany.

So the three years were as a reward for getting this very profitable order?

Germany and Telefunken

Ja. The negotiation with Telefunken was not easy. It took about three months, but eventually I was permitted to go to Telefunken.

Ja. 1937. That was maybe three or four years before the start of World War II.

Not that much before, because in 1938 Germany was already moving into countries.

So in 1937 maybe some connection between Japan and Germany existed. The preparations for war were underway. I studied at Telefunken for a year and a half learning about transmitting vacuum tubes for example, zirconium getter.

Getter means gas-absorbing materials in a high vacuum envelope.

That was new technology for Japanese vacuum tube manufacturers. I brought it back from Germany. Until 1965, Japanese vacuum manufacturers used dead-copy of my getter.

Waseda University & Tube Research

Before we go on, could I ask you a couple of questions about your electronics background from a little earlier in your life? There are two questions. Could you describe in a little more detail what went on at the Kodakura research laboratory, at Waseda University and what you did and learned there?

I studied photo tubes in Waseda after graduation from university and before joining JRC. Just after I joined JRC I was in charge of the oscillation tube, or magnetron, or the ultra-short-wave tube. As for the magnetron, it was suggested by Kiyoshi Morita of the Tokyo Institute of Technology. (Morita was the advisor of Heitaro Nakajima when H. Nakajima wrote his graduate thesis.)

Morita, assistant at that time, at the Tokyo Institute of Technology, was preparing his doctor's study. His topic was the short-wave tube. He ordered JRC to make a prototype tube or experimental apparatus. The magnetron. He became later professor of the Institute.

During the 1930s, when you were studying these tubes, how was knowledge passed? Was there available literature from other countries? Was there another group of people within Japan that was studying these? How did you learn about these things?

I'm sorry no information exchange existed among the companies in Japan. Toshiba was the only one tyrant.

I’ll explain the reason. There is a book titled The History of Electron Tubes published in 1987 written in the Japanese language. I am one of the co-authors. At the time of making this book I asked the Toshiba people why Toshiba had no patent concerning electron tubes. JRC had so many original patents. The answer was that the vice-president of Toshiba came from GE, and Toshiba people were not allowed to make such new technology as vacuum tubes.

Is there a journal literature in English or German? If there is, is it available? If that journal literature is available, does it tell you the things that you need to know, or do you need to have know-how about building these tubes that wouldn't be in the scientific literature? Those are the kind of things that I would like to know.

Some journal literature was available to the JRC Company. I read German journals everyday. Of course, some books from the United States would be available at that time, but I already forgot them.

Magnetron Development

Maybe we should continue then with the story.

Morita made a drawing of the magnetron and asked me to have JRC build it. I was very interested in such things, and also my brother Yoji Ito showed interest. He was in a Naval Research Institute. He was studying the Kennelly-Heaviside layer. He thought that some ultra high frequency, such as radar, would be useful because some reflection of electric wave would be possible.

So at that time Doctor Ito used to ask me for a weekly report. In 1934 he took leadership of the laboratory of vacuum tubes in the Naval Research Institute. At that time a special research contract was made between the Naval Research Institute and the JRC Company. My elder brother was not satisfied to invite only me, and he took some five or six vacuum tube workers from JRC to the Naval Research Institute at Meguro, Tokyo to build a group for manufacturing.

So the two groups were working independently.

But not completely independently very close coordination, and a very dutiful brother. Some differences though. At that time in my magnetron laboratory there were maybe three hundred persons — only for the magnetron. It was maybe the biggest magnetron factory in the world. At the Naval Research Institute, they discovered a special construction in which the frequency is very stable the stability is very good. That knowledge was fed back to JRC, so there was big and quick progress.

Finally JRC made such a device in 1939. It was a single-phase oscillator with ten-centimeter wavelengths. I believe this was the first one in the world and it had a five-hundred-watt output.

So this was the first one with that high an output?

Ja. It was also water-cooled.

At last the power went up to some hundreds of kilowatts or so. During the Second World War, many naval warships installed radar using our first developed water-cooled magnetrons.

That was earlier than the United States.

Radar and the Japanese Navy

But at that time there were so many opposite opinions in the Navy on using such radar. The reason why: with this thing and in a dark night with a light on, one could find a robber.

Maybe I should try to put it another way. The Japanese military authority, the Navy also, relied upon the optical weapons. Our optical technology was good, and they say that the Japanese have excellent eyes for watching with the optical aided tool (telescope, etc.). This was the main tool of the Navy, and they didn't appreciate the meaning of radio weapons. They looked down with scorn at such an idea. Yes, very skeptical.

Some top department of the Navy believed that radar was of no use very strange. They didn't believe in the electronics technology, I think. They didn't permit us to use the precious metals for the magnetron, such as cobalt for use in magnets.

The Navy wouldn't permit it?

No. Yoji Ito's group made about one hundred radars. They were not installed to big battle ships, but only small ships.

I see, so they were putting them into small ships that might have been fishing vessels.

Ja. At the last stage of the naval war in the dark night, the Japanese were worst hit by the United States. There must be some radar.

That is what made the Japanese Navy believe in radar? Is that what you are saying?

Right. So in late 1943 or so, the Japanese Navy began to think there must be radar in warships. At that time JRC people were obliged to make radar devices but also the Navy must install the devices, so, for example, Sogo Okamura and Seibun Saito were ordered to —

And also Ito could not continue their research.

So not only did you have an urgent plan to build all this equipment, but there was an urgent plan to get it installed. You even had to take away very good researchers to do this job?

Yes, right. You know, the vessels were not in Japan, but the place was just fighting. The authorities dispatched not only the operators but also excellent researchers to such places to install them.

The Japanese Navy installed radar earlier than the USA. Midway through the operation, the Japanese Navy was very heavily damaged. But at that time, in our northern sea area, the Japanese Navy dispatched two or three ships, on which was installed microwave radar and also an ultra high frequency radar.

Do you know the history, the story of radar? Ships with radar were very successful in retreating from the Aleutian Islands. There were many troops on each small island, and they would go back to the ship and return.

It was very successful, but Midway.

In the Aleutian area there was no United States Navy. But on the return to Japan, there was a very hard storm, and every ship was.

At that time microwave radar was very useful to confirm which ship —

The shipmasters confirmed the usage of radar, but at the time, still some top departments of the Navy didn't think that the radar was useful. General Isoroku Yamamoto personally asked my elder brother Ito to make an entirely new weapon. Without it, it would be impossible for Japan to win the war.

Wartime Weapons Research

Ito thought of the atom bomb. He frequently went abroad, so he knew that the U.S. had forbidden in 1939 the export of uranium ore. So he realized that the U.S. must have surely been planning to develop the atom bomb. He was thinking that Japan had to do something to prepare for this. In January 1940 he was sent to inspect war-preparations in Europe.

Doctor Ito got a Ph.D. under Professor Barkhausen in Dresden. Ito had very good knowledge of the German language. For example, he translated a tale for children from German to Japanese.

He was very fluent, and could get the kind of information the German army was very reluctant to reveal. This included their top-secret projects such as the Wurzburg radar and so on. But he was scheduled to stay just for two months. He was blocked because of the war, so he had to take ten months to just return from Germany to Japan.

Around South America. There was no transportation connection between Germany and Japan.

Ito finally came back to Japan and tried to prepare the radar as well as the atom bomb. He couldn't get information about the atom bomb in Germany, but he discussed it with the physicists (Professor Nishina, etc.) in Japan. There was a meeting and finally the famous Japanese physicists decided that Japan could not develop the atomic bomb, and also that in the United States it would be impossible to develop the atomic bomb during war time. My brother Yoji Ito told me personally several times that the United States surely knew how to make the bomb.

The next story is about the destructive ray. The JRC started developing bigger, higher power magnetrons at the laboratory in 1941, trying to kill a rabbit.

Kill a rabbit, yes. Successfully. Because General Yamamoto was asking Ito to make a new weapon to win the war, Ito was thinking about making a several thousand-kilowatt magnetron. With this microwave he could hit the airplanes and make the engine dysfunction somehow. He was thinking about it. So he established a new laboratory, at Shimada in Shizuoka Prefecture, and gathered lots of famous physicists, such as Tomanaga, Kotani, to develop this kind of high-output magnetron. But he was not very successful. The biggest magnetron they developed was from JRC. One of four company men, Sozaburo Yamasaki, made a magnetron of 20 cm wavelength, having the output power of 100kW. A more powerful magnetron having the output power of 1000 kW was undergoing trials as of August 1945.

In 1953 I traveled around the world without a translator. At that time I went to London, and at the museum I found exactly the same thing, which was explained as: "This was invented by some Birmingham University people in 1940." 1940 was one year later than our invention. When I found this one in the London museum, there was an explanation that this magnetron led to Allied victory for the Second World War. After that, a symposium was held in England by IEE, but at that time there was no exhibition of this magnetron. I felt very strange — why was that thing not then exhibited? That was 1985. At that time there were so many kinds of parts exhibited in many rooms, but there was no exhibition of this magnetron. I felt very strange and asked everybody, but there was no answer. After that, when I sat alone, taking some tea, one old gentleman hit my shoulder by the hand and told me, "Your magnetron must have been stolen by the English King." That was an interesting thing.

Postwar Microwave Research

Maybe we should turn to the post-war period?

In the post-war period the general headquarters of the Occupation Force was very stringent in restricting what should be manufactured. In the case of the JRC Corporation, radio receivers and medical equipment could be produced, but not transmitters.

But three or four years’ later, wireless equipment for marine use was permitted. Therefore, we could produce transmitting vacuum tubes, so we could make a profit from that. Getter is gas-absorbing material in the vacuum tube to keep a high vacuum. At that time JRC was almost the only producer for that. Its market share was ninety-eight percent or so.

Ja. We had the orders also from the United States. In one year, two hundred million vacuum tubes were produced in Japan. So we could make money by means of getter production.

The difficulty was because of the GHQ, but they could survive because of getter.

At that time, only the JRC Corporation had microwave engineers. JRC had more than one hundred microwave engineers, and I had to consider what kind of jobs they must be doing.

Because you were now the manager of the research and development division?

Ja. I thought that if the microwave was used, multiple communications could be possible: for example, the telephone. At the first stage I considered multiplex telephone transmission by frequency modulation using a variable-frequency magnetron. But instead of frequency- modulated equipment, there was a patent by Professor Nagai of the Tohoku University, called PTM, which is pulse time modulation. We thought this type would be better, so we produced some trial equipment. We prepared to make some experiment between Mount Futago at Hakone near Fuji Mountain and the JRC Corporation in Mitaka that was heard by the General Headquarters and the Electric Communication Laboratory at that time also knew about that experiment.

So the experiment hadn't occurred yet, but word about this had been learned by both the Electric Communication Laboratory and by the GHQ?

At that time, transmitting electromagnetic waves had to be approved by the authorities. I went to the Electric Communication Laboratory to ask for the approval.

I see, so not only did they just happen to hear it, they had to have heard about it because they had to give their approval.

The president of the Electric Communication Laboratory did not understand the usage of electrical wave for communication. He thought it was nonsense to use such an unstable propagation wave for communication equipment. But at that time one very important person named Frank Polkinghorn of GHQ visited the Electric Communication Laboratory and found that there were no experiments about microwaves. He was surprised.

But at that time, the president answered. Of course, meanwhile we were ready to make the experiment, elsewhere.

I'm not sure I understand. So Polkinghorn says, "Aren't you doing any microwave research?" The president of the Electric Communication Lab says, "Oh, yes, we're going to do this and that, but we're not going to do it here." Is that it?

JRC tried to establish a test from Mount Hakone to JRC. To get the approval, the Electric Communication Laboratory had denied JRC the use of radio. But the GHQ officer named Polkinghorn, a civil communications service officer, asked the director of the Electric Communication Laboratory, "Why aren't you promoting microwave study?" Therefore the director of the ECL commanded JRC to stick a new label over the label of JRC, "Electric Communication Laboratory," and just go test.

So that it looks like ECL's rather than JRC's.

Right. Basically the company was correct, but was much indebted to Mr. Polkinghorn of GHQ.

Fish Detection Equipment

This is now about fish finding. The history is that Navy men were using an ultrasonic submarine detection system and finding a strange phenomenon. It would identify a submarine but then the submarine would suddenly be gone, and they suspected that it would be a school of fishes. I heard the idea, and after the war I tried to use this idea to find a school of fish. I proposed this idea to GHQ to make an experiment. GHQ declined because this was related to weapons. But I insisted, "No, we can use even one sardine on the table, we are so short of fishes." I asked several times over two years, but GHQ declined very adamantly. I asked my elder brother, Dr. Ito, and he asked Dr. Kelly who saved the Japanese science and technology in post-war years. Ito insisted, so Kelly finally gave secret permission to me to do an experiment. When we did the experiment, we very clearly identified a school of fish. That experiment was successful. I really believe that Kelly was a sort of saint, that he saved Japanese science and technology. He was an intimate friend of my brother's, and there are words dedicated by Kelly when my brother died.

I see. This is Harry C. Kelly.

Harry C. Kelly, yes. That experiment was successful, but fishermen were skeptical at first. They thought that with their long experience, they knew how to find fish. But the experiment was successful. They could get a lot of fish, so the fishermen were enthusiastic about this device. This now costs fifty thousand, but at that time about a million Yen.

Demand was so great that we sold out of this device, so the fishermen had to wait. We exported it to the U.S. and many other countries.

A newspaper company was very interested and asked to come on board to witness the experiment. Then the findings of the successful experiment were broadcasted nation-wide. The first cost was a million yen, but we changed it from nickel oscillator to an oxide compound. BaTiO3. This is manufactured by Murata, a Japanese company, and was a Japanese invention. Because of this innovation, the cost went from a million to fifty or sixty thousand.

After that I visited RCA and the Bendix Company, and showed the device. That surprised the engineers at Bendix because they were just borrowing that device from the Navy to develop their weapons. Probably the Navy also kept that device.

Can I go back and ask a question about the experiment on the communications channel? Did that succeed, and did it result in a technology that was implemented in the country?

Ek dink so. It was successful. It was the beginning of Japanese multiplex telecommunications by microwave.

But did it directly stem from this particular experiment, or did it come from some other direction?

The main topic for him was the oscillation of the magnetron wave and the reception of the magnetron wave.

I see. So you were far from being at a communications system at this point you were just showing proof of principles?

To show a transmission line using PTM method.

A certain doctor was interested in this fish-finding device and asked me to try to use this device to diagnose on the human body, the conditions of organs. I was at first very surprised but tried to develop a device. It was a very difficult process, and it took about twenty years. I was also asked to use this device for meteorological purposes. When did meteorological radar begin to be used in the United States?

All principal points have been covered. You know that this fish finding and diagnosis is the beginning of his present company, Aloka. Fish finding is one of the best sales of JRC, and it was a peaceful application. Communication was a peaceful application, the main peaceful application of radar technology. I think he contributed much not only to the military application, but also.

Also to these commercial ones.

Yes, and I think that he is very proud of that, being one of the real original developers of the magnetron technology.


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