^ Ai^-'l Given By .CFDocm'-vms Lt 0^7?^- THE UNITED STATES STRATEGIC BOMBING SURVEY The Japanese Aircraft Industry AIRCRAFT DIVISION a \o. \^ May 1947 THE UNITED STATES STRATEGIC BOMBING SURVEY The Japanese Aircraft Industry AIRCRAFT DIVISION May 1947 PUBLIC J, ^ , Xe^c- Qf U0»iU«»M««4 This repoi't was written primarily for the use of the United States Strategic Bombing Survey in the preparation of further reports of a more comprehensive natm'e. Any conclusions or opinions expressed in this report must be con- sidered as limited to the specific material covered and as subject to further interpretation in the light of fm-ther studies conducted by the Sm-vej'. FOREWORD The United States Strategic Bombing Survey civilians, 350 officers, and 500 enlisted men. The was established by the Secretary of War on 3 military segment of the oi'ganization was di'awn November 1944, pursuant to a directive from the from the Army to the extent of 60 percent, and late President Roosevelt. Its mission was to con- from the Navy to the extent of 40 percent. Both duct an impartial and expert study of the effects the Army and the Navy gave the Survey all of our aerial attack on Germany, to be used in possible assistance in furnishing men, supplies, connection with air attacks on Japan and to estab- transport, and information. The Survey op- lish a basis for evaluating the importance and erated from headquarters established in Tokyo potentialities of aii- power as an instrument of early in September 1945, with subheadquarters in military strategy for planning the future develop- Nagoj'a, Osaka, Hiroshima, and Nagasaki, and ment of the United States armed forces and for with mobile teams operating in other parts of determining future economic policies with respect Japan, the islands of the Pacific, and the Asiatic to the national defense. A summary report and mainland. some 200 supporting reports containing the find- It was possible to reconstruct nuich of wartime ings of the Survey in Germany have been Japanese military ])lanning and execution, en- published. gagement by engagement, and campaign by cam- On 15'August 1945, President Truman requested paign, and to secure reasonably accurate statistics that the Survey conduct a similar study of the on Japan's economy and war-production, plant effects of all types of air attack in the war against by ])lant, and industry by industry. In addition, Japan, submitting reports in duplicate to the studies were coiiducted on Japan's over-all Seci'etary of War and to the Secretary of the Navy. strategic plans and the background of her entry The officers of the Survey during its Japanese mto the war, the mternal discussions and negotia- phase were: tions leading to her acceptance of unconditional sin-render, the course of health and morale among Franklhi D'OIier, Chairman. the civilian population, the effectiveness of the Paul H. Nitze, Henry C. Alexander, Vice- Japanese civilian defense organization, and the Chairmen. eft'ects of the atomic bombs. Separate reports Harry L. Bovvman, will be issued covering each phase of the study. J. Kenneth Galbraith, The Sm'vey interrogated more than 700 Japa- Rensis Likert, nese military, government, and industrial officials. Frank A. McNamee, Jr., It also recovered and ti'anslated many documents Fred Searls, Jr., which not only have been useful to the Survey, Monroe E. Spaght, but also will furnish data valuable for other Dr. Lewis R. Thompson, studies. Arrangements have been made to turn Theodore P. Wright, Directors. over the Survey's files to the Central InteUigence Walter Wilds, Secretary. Group, through which they will be available for The Survey's complement provided for 300 further examination and distribution. TABLE OF CONTENTS Page I. Summary 1 II. The Japanese Aircraft Industry 6 A. Background 6 B. Who Was Who IN THE Aircraft Industry 13 C. Characteristics of the Wartime Aircraft Industry 20 D. Plant Dispersal 31 III. Japanese Aircraft—the Product 67 A. Service Ty'pes—General 67 B. Conventional Aircraft 73 C. Advanced Ty'pes 73 D. Design Fe.a.tures 87 E. Quality 90 IV. Materials for Aircraft Construction 93 A. Material Control 93 B. Critical Raw Materials 93 C. Effect of Shortages on Airplane Engines 98 V. Parts and Component Manufacture 100 A. Propeller Industry^ 100 B. Other Components 105 VI. Air Attacks on the Aircraft Industry 109 A. Target Selection for Strategic Bombing 109 B. Direct Attacks 110 C. Indirect Attacks 120 D. Effectiveness of Bombs ^ 120 E. Persistency of Attacks 120 F. Physical Dam.'VGE Inflicted 125 G. General Conclusions 125 VII. Intelligence Check—Forecasts vs. Findings 130 Appendix I. Aircraft Division, USSBS, Pacific 138 II. Corporation and Plant Reports 141 III. Outline of Plant Report 141 IV. Outline of Corpor.^tion Report 143 V. Reply' to Questions of USSBS by Okano 144 VI. Munitions Company Act ._ 146 VII. List of Component and Accessories Suppliers 150 VIII. List of Principal Suppliers of Metals 152 IX. Propeller Requirements AND Production byTypes, 1941-45- 153 X. St.\tistics 155 Part I SUMMARY There is little need to establish here the im- in aircraft dehveries. In 1941, 5,088 planes (more portance of Japan's aircraft industry to her war than four times the 1936 output) were made avail- effort. Both in day-to-day tactical applications able to the mihtary forces. But the real expan- and in plans for a final all-out "Kamikaze" de- sion, the "all-out" national effort, came during fense of the homeland, the high command counted the war years, 1942 to 1944. Nearly six times heavily on the air force of the Army and Navy. as many airplanes roUed off the lines in 1944 Obviously, it was of vital importance to them to as in 1941. The effort was even greater than keep new aircraft flowing from factories to opera- the figures indicate, because the aircraft in- tional units and to our interest to disrupt that creased in weight and improved in performance, flow. It was not chance, therefore, that ear- and because the ratio of combat types to trainers marked Japan's aircraft industry as the number and transports went up. Of the 28,180 produced one target for our bombers. in the peak j^ear, 1944, three-fourths were combat It is now apparent that the Jap fell far short types. of his owTi expectations for aircraft and engine Measured against the volume of aircraft produc- production even before the weight of out bom- tion in the United States for the same years the bardment fell on the home islands. By the time Japanese totals are not great, but taking into we came within striking range, internal economic account the relative resom'ces of the two countries conditions were deteriorating rapidly. Essential in materials, manpower and technological develop- supplies were dwindling, skilled manpower was ment, the effort was creditable. Table I-I shows short and morale was declining. How soon the the total output for aircraft, engines and propellers tide might have turned had we not bombed the in the war years. For comparative pm-poses, the aircraft plants directly is, of course, a matter total aii'craft production figures for the United for conjecture. When we struck, the industry States and for Germany have been set up m was already decidedly sick. Our attacks not only Table I-II. certain that any recovery would be com- made Table I-I.—Japanese aircraft, engine and propeller produc- pletely impossible, but also forced production of tion by years 1941-45 aircraft engines, propellers and finished combat aircraft well below what would otherwise have been obtained. The prewar history of the Japanese aircraft industiy is not impressive. In the years since 1918 an industry of sorts had been built up mainly around designs obtained under license from Ger- man, British and United States manufacturers. A scattering of small shops provided a miscellany of militaiy and commercial types during the 1920's and formed the nucleus of the prewar expansion. A few big names (Mitsubishi, Nakajima, Kawa- saki) thread back tlu-ough the whole pattern. A number of smaller fry were brought into the indus- try during the course of the war. Slowly and irregularly Japanese aircraft pro- duction rose from a modest 445 planes in 19.30 to 1,181 in 1936. During the next 5 years, a period of fighting in China and of preparation for Greater East-Asia co-prosperity, there was a rapid rise appeared. No less than 90 basic types (53 Navy photographic evidence on that score. With few and 37 Army) and 164 variations on basic types exceptions the plants hit were made useless for con- (112 Navy and 52 Army) were carried on our tinued production. Some departments escaped identification lists. Not all were in production at direct hits or fire damage and certain well pro- any one time. Such diversification may have tected heavy equipment (hydrauhc presses, heat- seemed necessary to the tacticians, but it did not treating furnaces and forging hammers) was kept make procurement any easier. in operation by prodigious effort. Operations, During the course of the war, emphasis shifted however, were generally disrupted and scattered from bombers to fighters as operations became and operating efficiency knocked down well below more and more of a defensive character. The the average level. same trend was observed in Germany during the By late spring of 1945, some of our attacks fell latter phases of the European war. There, how- on practically empty plants. The tools and per- ever, it was of greater significance because the somiel they had original^ housed had "taken to change-over to single engine fighters tended to the hills." Following the initial strikes by B-29s reduce the load on industry in terms of airframe in November and December 1944, a panic dis- weight.