Kyushu Airplane Company
(Kyushu Hikoki K K)
Corporation Report

Aircraft Division
February 1947

  • The following is from the records of the United States Strategic Bombing Survey (Pacific). PDF original may be found at under "United States Strategic Bombing Survey."
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Kyushu Aircraft Co - front page


Kyushu Airplane Company
(Kyushu Hikoki KK)



Aircraft Division

Dates of Survey: 13-15 November 1945

Date of Publication: February 1947


The Corporation and Its Importance in the Aircraft Industry
The Air Attacks
Production Statistics
Evaluation of Pre-attack Intelligence
Appendix A—Layout of the Zasshonokuma Plant
Appendix B—Layout of the Kashii Plant
Appendix C—Layout of the Itazuke Plant
Appendix D—Organizational Table of the Kyushu Airplane Co.
Appendix E—Component Flow to Final Assembly of the Four Types of Aircraft Manufactured During 1945
Appendix F—Graph of Employee and Manhour Trends
Appendix G—Indirect, Direct and Total Manhours Worked
Appendix H—List of Dispersal Locations
Appendix I—Map of Dispersed Sites
Appendix J—Table of Ordered and Actual Production
Appendix K—Graph of Ordered and Actual Production
Appendix L—Comparison of MIS Estimates with Actual Production



The Kyushu Airplane Co. (Kyushu Hikoki K K) was a significant producer of naval trainer aircraft and the foremost aircraft manufacturer on the island of Kyushu. During 1943 this firm produced about 12 percent of the total output of naval trainers but only three percent of the total combat planes. With the production of the Type O reconnaissance seaplane, Jake, in 1941, Kyushu Airplane Co., then known as the Watanabe Ironworks Ltd (Watanabe Tekkosho K K), started assembling combat aircraft. Production of another combat type, the Tokai patrol bomber, Lorna, began in September 1943. Subsequently, in June 1945 Kyushu completed the development of the first of a new pusher-type naval fighter, Shinden. Only one aircraft of this type was completed prior to the cessation of hostilities. Plans to produce the twinjet aircraft, Kikka, were never fulfilled and no models of this Nakajima-designed aircraft were ever produced by Kyushu.

As a producer of aircraft landing-wheel units, Kyushu was second only to the firm of Okamoto Industries Ltd (Okamoto Kogyo K K). Wheels manufactured by Kyushu were delivered to all the principal producers of naval aircraft including Mitsubishi, Nakajima, Kawanishi, Aichi and Hitachi.

Prior to the formation of the Kyushu company in 1943, this concern was known as the Watanabe Ironworks. It was founded in 1886 by Fukuo Watanabe. In 1919 this firm commenced the manufacture of torpedo tubes and parts for the Imperial Japanese Navy at its plant at Chiyomachi near Higashi park in the town of Fukuoka.

Watanabe anticipated the future importance of the aircraft industry. Realizing that there was no aircraft-manufacturing activity on the island of Kyushu other than the small-scale production then taking place at the Sasebo naval arsenal, he became determined to start aircraft manufacture in a section of his ironworks. During the early 1920s, when Watanabe started making plans for aircraft manufacture, funds were not available for the anticipated assembly of complete airplanes, so the manufacture of aircraft landing wheels was decided upon as a logical beginning.

Although Watanabe's previous connections had been almost entirely with the Japanese Navy, the Army was the first to place orders for the manufacture of landing wheels. The Navy soon followed suit, however, and finally, realizing his closer associations with this service, Watanabe in 1926 sought orders for the manufacture of complete aircraft with the Naval Air Headquarters. Despite repeated attempts, orders were not forthcoming until 1929 when Admiral Ando, then the chief of Naval Air Headquarters, offered the Navy's full cooperation in establishing a new plant in which Watanabe was to manufacture aircraft for the Navy. The site chosen for the new plant was at Zasshonokuma on the southeastern outskirts of Fukuoka.

Difficulties encountered in the construction and operation of the new plant were overcome with the help of the Navy which supplied engineers and technical specialists. Furthermore, limited numbers of Watanabe personnel were trained in aircraft production techniques at the Sasebo naval arsenal which was then the only naval arsenal in the area engaged in aircraft production.

Construction of the Zasshonokuma plant (Appendix A) was completed late in 1930, and production started in 1931. A new Watanabe ordnance plant was built adjacent to the Zasshonokuma aircraft plant and ordnance manufacture, on a larger scale than previously, was commenced at this new site in 1934.

By 1940, the site of the Zasshonokuma plant had been fully built up, and in order to accommodate additional expansion, the acquisition of more land and the construction of further plants was envisaged. In 1941, the Kashii plant (Appendix B) was constructed on reclaimed land to the northeast of Fukuoka, and in the following year, landing-wheel manufacture was transferred from Zasshonokuma to a newly constructed plant at Itazuke (Appendix C) , one mile north of Zasshonokuma.

By 1943, both the aircraft and ordnance divisions of Watanabe had grown to such proportions that it was decided to create two distinct organizations. Watanabe remained as president of both, and the personnel were allotted with respect to their previous activity in the manufacture either of aircraft or naval ordnance. In October 1943. therefore, the Kyushu Ordnance Co. (Kyushu Heiki K K) and the Kyushu Airplane Co. were established.

During 1944, lesser plants of Kyushu Airplane were constructed at Setaka, 35 miles south of Fukuoka, and Karatsu, 30 miles west-southwest of Fukuoka (Fig. 1).

Kyushu Airplane Plants Map

Another small plant was built at Meinohama, 5 miles west of Fukuoka, in 1945. The Kyushu Airplane Co.'s manufacturing facilities (Table 1) therefore, consisted of two aircraft-assembly plants, one landing-wheel plant, and three lesser parts plants.

Kyushu Airplane Functions

The Army, Navy and Munitions Ministry did not exercise a strong influence over Kyushu, whose failure to meet production orders did not arouse criticism or stricter control. A parallel may be drawn with Japan International Aircraft Industries, Ltd (Nippon Kokusai Koku Kogyo K K), another firm of secondary standing engaged largely in the manufacture of trainers for the Army, and whose low output was never a matter of concern to the officials of the Munitions Ministry.

Other than naval assistance in the construction of the plant and the training of skilled workers, only one instance is known in which the Navy rendered direct assistance to Kyushu. This was in the designing of the pusher-type aircraft, Shinden, in which case a naval aeronautical engineer who had a mania for, and specialized in the design of 'ente' (duck)-type aircraft, was directed by the First Naval Air Technical Depot at Yokosuka to supervise the designing of Shinden at the Zasshonokuma plant.

Financial control of Kyushu was exercised principally by the Sumitomo Metal Industries Ltd (Sumitomo Kinzoku Kogyo K K) , and the Watanabe family and friends. Each of these groups owned about 40 percent of the shares while the remaining 20 percent were privately owned. No subsidies were ever received by Kyushu from the government, and no direct supervision other than the inspection of finished products was exercised by the Navy.

Early in 1945 the Munitions Ministry allotted secret code numbers to all aircraft plants in Japan. Under this system, the various divisions of the Kyushu Airplane Co. received designations as follows:

Headquarters department -- No. 1030
Zasshonokuma plant -- No. 1031
Kashii plant -- No. 1032
Itazuke plant -- No. 1033

Organization and Operation

The three principal plants of the Kyushu Airplane Co. were under the administrative control of a headquarters department located at the Zasshonokuma plant (Appendix D).

This headquarters department controlled activities of its six departments through the direction of the president, Fukuo Watanabe, the vice-president, Z. Yamamoto, the managing director, K. Ozaki, and a board of five directors and three auditors. These six departments were responsible for general affairs, personal affairs, accounting, materiel, training and medical activities of the whole firm. The branch offices and agencies of Kyushu in Tokyo, Osaka, Nagoya, Hiroshima, Omura, and Fusan were also under the control of this headquarters.

The general affairs, planning, designing and production departments of the Zasshonokuma plant were under the control of S. Yamanari, the plant manager. Similarly, the general affairs, training, planning and production departments of the Kashii plant were under the jurisdiction of M. Matsuo. The Itazuke plant, relatively smaller than either of the above-mentioned units, and engaged only in the production of landing wheels, was divided into general affairs, planning and production departments under the direction of the plant manager, M. Yamada.

Production-flow charts for the four aircraft types being assembled by Kyushu Airplane during 1945 (Appendix E) show that with very few exceptions all subcontractors and parts suppliers were located on the island of Kyushu.

As the Kyushu Airplane Co. had for many decades been well established in the Kyushu area, it had organized a reasonably effective group of subcontractors in the immediate vicinity of its assembly plants. The supply of components, therefore, was not such a limiting factor as was the case with the more recently established Mitsubishi No. 7 airframe works at Kumamoto. As an example, Kanegafuchi's spinning mill in Fukuoka city manufactured Shiragiku fuselages under subcontract to the Kyushu Airplane Co.

Owing to the lack of impetus and the relatively small volume of production at all the plants of Kyushu, the production techniques were almost without exception the "job shop" variety.

Although the population in the Fukuoka area more than fulfilled the demands of Kyushu for unskilled labor, the lack of technicians, specialists and skilled workers was considered a significant limitation to the achievement of maximum output. Total employment at the Kyushu Co.'s plants rose steadily from 5,000 in April 1939 to 17,000 in the middle of 1943 (Appendix F). A small drop in employment is evident towards the end of 1943, due to the conscription of a group of men for service in the Japanese armed forces. During 1944, however, employment rose rapidly again, and with the utilization of student labor and soldier employees in April and July 1944, respectively, employment reached its height in February 1945, with a total of almost 27,000 laborers. Many of the students were forced to return to their schools during May and June 1945, causing a sharp drop. At the conclusion of hostilities, 20,000 people were in the employ of the Kyushu Airplane Co. and by October 1945, the figure had dropped to 1,664.

Although man-hour figures (Appendix G), indicate that the effort was almost equally divided between direct and indirect labor, officials stated that 60 percent of all regular employees, all of the soldiers, and 75 percent of the students were utilized in direct-production departments of the company.

A two-shift system was utilized in all the plants and departments of the company. The hours of the day shift were from 0730 to 1845 hours and of the night shift, from 1845 to 0730 hours. Personnel on shifts were reversed each Sunday.

With the exception of January 1942, during which month the labor turnover was particularly high, the average ratio of new employees hired during the month to the total number of employees at the beginning of that month was 1:34 for the years 1942 and 1943. This ratio was maintained throughout 1944, with the exception of April and October of that year, during which two months an unusually large number of students was hired to replace men conscripted for military service. During the first eight months of 1945 the turnover was small, the average ratio for this period being 1:74.

During the months immediately following December 1944. approximately 4.500 workers, or 50 per cent of the total available skilled-labor force, was conscripted by the Army and Navy. The firm was powerless to prevent this continual drain on irreplaceable manpower, and the resulting effect on production was considerable.

Appended Plant Reports

Although all the plants of the Kyushu Co., with the exception of the Setaka plant, were investigated by members of the Kyushu field team of the Aircraft Division, it was considered that their size and significance was not sufficient to justify the preparation of any individual plant reports. All the information supplied by company officials and obtained from investigations by survey personnel has therefore been included in this corporation report.

The Dispersal Program

Plant officials of the Kyushu Airplane Co. realized the threat of air attacks, and planned to take action in December 1944. In that month, a preliminary dispersal program was instituted, and in addition to the movement of equipment and personnel to available sites in the Fukuoka area, buildings were removed from the Zasshonokuma plant, and the construction of more permanent dispersal sites, both above and underground, was started.

This plan was put into effect during the first quarter of 1945. Due to the destruction by air attack of aircraft-manufacturing and air-depot facilities at Tachiarai (20 miles SE of Fukuoka) on 1 April 1945, the government ordered the Kyushu Airplane Co. to expedite the completion of its dispersal program and to modify the plan so as to make it as extensive as possible and to effect the dispersal of all vital machinery and essential activity.

Of the 29 principal dispersal groups to which activity was transferred (Appendix H), seven were located in schools, five partly or wholly underground; one was a forest dispersal; and the remainder were housed in newly constructed installations, warehouses, public halls, or any other enclosed site with the requisite floor area (photos 1-4).

Photo 1. Entrances to underground machine shops of the
Kashii-miya dispersal group.

The decrease in output from 133 aircraft in December 1944 to 76 aircraft in January 1945, and the further drop to 26 in April 1945 is indicative of the sacrifices in production that were made in order to achieve maximum dispersal.

With one exception, all dispersal was effected within a radius of 10 miles of the parent plant (Appendix I). In this way difficulties encountered in the transportation of supplies and workers were kept at a minimum.

Ohashi Plant
Photo 2. Dispersal from the Itazuke plant; machine shop located in
forest near Ohashi. Note trees growing through center of building.

Wajiro 01
Photo 3. Dispersal of the Kashii plant to Wajiro showing
five of about 15 entrances to incompleted tunnels.

Wajiro 02
Photo 4. Dispersal of the Kashii plant to Wajiro showing two of a group of six hangar-type structures camouflaged with bamboo lattice-work and brush.


Air Attack on Plants

None of the plants of the Kyushu Airplane Co. was ever the target of, or damaged by, air attack.

Air Attacks on Urban Areas

The Fukuoka urban area was attacked on 19 June 1945. Although 20 percent of the built-up area was destroyed as a result of this raid, company officials stated that minor dislocation in the transportation of workers existed for only one day subsequent to the raid. Effects on production were negligible.


A tabulation of production data (Appendix J) shows that between April 1942 and August 1945, the company produced only 2,418 planes or 53 percent of the 4,517 aircraft ordered from it by the Munitions Ministry. This low output placed the firm among the secondary aircraft manufacturers, and it is known that the government made little or no attempt to spur the firm on to greater efforts.

Prior to 1939, output consisted almost completely of trainer aircraft, these being produced in relatively small numbers. By 1941, the annual output had reached 300 aircraft, and it was in this year that Kyushu completed its first combat aircraft, the Type reconnaissance floatplane, Jake. Although the Type 96 fighter, Claude, had been produced since 1940, this type was never used extensively in the Pacific war, being by that time considered obsolete and having been replaced by Mitsubishi's Type fighter, Zeke, as equipment for Japanese aircraft carriers. During 1940 and 1941, the company delivered 59 percent of the orders placed by the Munitions Ministry. This general percentage was maintained throughout 1942, 1943 and 1944 (Appendix K), but dropped sharply when the dispersal program was jut into effect early in 1945. As a result of dispersal, output dropped from a peak of 133 aircraft in December 1944 to 26 in April 1945. After a slight recovery in May and June 1945, output dropped again to 18 in August 1945. Dispersal, however, was not the only factor which contributed towards decreased output in 1945. The supply of raw materials and parts was failing, and area attacks on cities in Honshu had dislocated the delivery of electrical parts and other vital components from Osaka, Nagoya and Tokyo.


Owing to the small quantity and, in most cases, the complete lack of valid source material on which the production of trainer aircraft could be estimated, MIS figures for trainer aircraft output by Kyushu were far too high. Although the Type 2 primary land trainer (K9WI) and the Type 2 intermediate land trainer (KiOW1) went out of production in June 1943 and November 1942, respectively, they were each carried at the monthly rate of 10 for January 1945. The only bases for such estimates were vague documentary sources and sightings on enemy airfields. Again, in the case of the trainer, Shiragiku, the estimate of 100 aircraft for January 1945 was on the high side, for although 70 aircraft of this type were completed in December 1944, this was a false peak and regular production was of the order of about 30-40 aircraft per month during the last months of 1944 and the beginning of 1945.

Comparison of estimates and actual production of combat aircraft (Appendix L) is more favorable owing to the larger volume of information available. Estimates of Jake production closely paralleled actual output until April 1945, when dispersal caused a drop in production not reflected by estimates, owing to lack of photo cover and other data indicating dispersal at this time. As captured ferrying schedules were the only sources on which estimates of Lorna output could be based, graphs of estimated and actual production do not coincide closely. A further comparison may be made, however, with the total number of Lorna aircraft actually produced and the estimated total. The former figure amounts to 153 and the latter to 161 aircraft, an error of 5 percent. In the case of Shinden, a total lack of basis for production assessment caused an arbitrary rate to be assigned of 3 aircraft monthly from December 1944, to June 1945, although only one aircraft of this type was ever completed.

With the exception of one or two types of trainers in production in the early 1930s, MIS information accurately covered the types of aircraft included in Kyushu Airplane Company's output. The location and significance of their three principal plants were known, as was the system used in transporting test flights and acceptances. Although it was thought by MIS that Mitsubishi had a share in the control of the Kyushu Airplane Co., this did not turn out to be the case. It was also known to MIS that the former Kanegafuchi Industries Ltd (Kanegafuchi Jitsugyo K K) spinning mill in Fukuoka had been taken over by Kyushu Airplane Co. for the manufacturer of components and subassemblies.

Appendix A - Building Plan, Kyushu Airplane Co., Zasshonokuma Plant (August 1945)

Kyushu Airplane Co. Plan

Appendix B - Building Layout Plan, Kashii Plant (August 1945)

Kyushu Airplane-Kashii

Appendix C - Building Plan, Kyushu Airplane Co., Itazuke Plant


Appendix E1-E4 - Aircraft Production Flow Charts

Shinden Prd Flow

Lorna Prd Flow

Shiragiku Prd Flow

Kikka Prd Flow

Appendix H - Dispersal from the Plants of the Kyushu Airplane Co.

Kyushu Airplane Dispersal

Appendix I - Location of the Dispersal Sites of the Three Principal Kyushu Airplane Plants

Kyushu Airplane Plants

Appendix J - Production Statistics, April 1931 - August 1945

Kyushu Airplane Production

Fukuoka Camp #1


Fukuoka Targets