Japanese Air Power

by E Speyer
When Mr Speyer's estimates were first published in England he was reproached for, over-estimating Japan's industrial strength, Now, however, both official circles and experts agree that previously published figures were much too low and his estimates, which are not meant to be anything but "probables" are generally accepted … In this article, he has revised and brought up to date for Aviation's readers the analyses which appeared in the Royal United Service Journal and Aeronautics. 'We are grateful to both publications for permission to use some of the material which appeared in their columns. —The Editor
A new analysis reveals that Nippon's current strength and ability to produce aircraft shows dangers of underestimating her as a formidable foe.

The reticence of the Japanese with regard to their armed forces has become almost proverbial, and the most closely guarded of their secrets during the last few years has been their air strength. While it is therefore impossible to give exact data concerning the air arm of their two services (the Army and Navy each has its own air force) certain conclusions can be drawn from plans and statistics published in Japan, from figures relating to the trade between Japan and other nations and from public utterances by Japanese government, military and business authorities.

Certain deductions may be made from these factors which, though they may err to some extent, will help avoid the most dangerous mistake possible in war — to underestimate the strength of the enemy.

The history of the Japanese air forces dates back to 1911, when two army officers, after having received training in France, went home as the first Japanese airmen. During the first World War a Japanese air mission visited the Italian front in 1918. In February, 1919, 60 French aviators led by Colonel Fauré went to Japan to become the first real teachers of the Army air force. That same year an aviation section was created in the Army Department and the first aviation school was established near Tokyo in 1920, with two more being opened in 1922. In June, 1925, the Army Aviation Corps was made an independent part of the Army and placed on an equal footing with the infantry, cavalry and artillery.

Naval aviation, too, had an early start. In 1912 Japanese naval officers went through training in France and the United States. The Naval Air Service was founded in 1921, and the next year was thoroughly reorganized by a British mission under Capt Senville. In April, 1927, following the example of the Army, the Navy created an Aviation Department. In April, 1928, a squadron of aircraft tenders consisting of the Akagi, Hosho, and two destroyers were organized as a standing unit of the fleet.

By 1938 Japan had eight military aviation and aero-technical schools in addition to at least two naval training centers.

Aviation Status Raised

In 1938 the status of the military wing was raised by the appointment of an Inspector-General of military aviation, and in the same year both the Army and Navy started a very ambitious expansion program. The following figures will give an idea of the strength of the Japanese air force in that year. To be on the safe side they should be regarded as referring to early 1938; they are the latest which have been published:

Army Air Force squadrons —
  36 Observation……297 airplanes
  35 Fighter……350 airplanes
  15 Bomber……150 airplanes
  Total first line……797
  Second line, all types……850
Naval Air Force
  Patrol flying boats……600
  Carrier-borne aircraft……400
  Total first line……1,000
  Second line, inc
obsolescent types

According to 1938 statistics, the aviation personnel (pilots only) consisted of 2,500 Army Air Force and 2,000 Naval Air Force pilots. Private estimates of current strength of the Japanese air forces published in the United States shortly after the outbreak of the Far Eastern war gave a figure for first-line aircraft of 3,000 to 5,000, but it seems likely that even the higher of the two figures is much too low.

The Japanese possessed an important aircraft industry even in 1933, the year of Hitler's rise to power. During that year 2,140 airplanes and 3,900 engines were produced. By 1936 a Japanese publication estimated annual capacity at 3,060 aircraft and 6,850 engines. Part of the production in the years before the war was for civilian use and export but, on the other hand, aircraft and components were imported from Germany, Italy and, up to the second half of 1938 when the "moral embargo" came into force, from the United States.

We may therefore, for simplicity's sake, neglect production for civilian use and export as well as import, and also what was produced before 1933. We then arrive at the following estimate of production for airplanes alone:


That means a total production of 13,760 for military purposes up to the beginning of 1938. If we regard 60 percent of this figure as non-operational aircraft and allow for 15 percent loss through accidents, etc, there would still remain about 4,700 operational aircraft, against about 3,700 in figures cited earlier in this article, which might indicate at hidden reserve of about 1,000 airplanes.

Clue To Production Gains

For production after 1936 we have an important clue: in September, 1941, a high authority of the Press Bureau of the War Ministry in Tokyo declared that the output of aircraft was ten- times that of four years previously. Even allowing for gross exaggeration, and taking the truth to be about 50 percent, the output during 1941 would have been in the neighborhood of 15,000 airplanes. The following production figures, although hypothetical, can therefore be regarded as conservative estimates.


That is a total production since 1938 of 35,000 aircraft. Allowing 50 percent — 17,500 — for non-operational aircraft and 1,000 planes as lost in the China war, deducting the 1938 production on the improbable basis of being entirely obsolete, and deducting a further 15 percent for accidental loss, there would still remain about 12,300 operational airplanes from the 1939-41 production. If, again, we disregard the 1939 production as not up to modern standards, we arrive at a figure of about 10,000 airplanes from the production years 1940 and 1941.

Opinions differ as to how many of these are first-line and how many are second-line, especially as the meaning of these expressions is by no means clear. Some regard as first-line only those airplanes involved in, or ready for, actual lighting regardless of the year of construction, while all planes held in reserve are second-line. Others regard as first-line only those aircraft which were produced during the previous year. If the latter view is accepted, the first-line strength of the Japanese air forces would be approximately 6,000.

Whether an airplane is obsolescent or obsolete depends, apart from technical viewpoints, upon the opposition it might encounter. An airplane which can still be used, or could until recently, in China, might be entirely useless against British, Dutch or American opposition.

It is still too early to know whether the Japanese air forces use extensively any airplanes of unknown or more recent construction than the Zero. According to German reports a new type fighter, the Mayabusa recently appeared over Tokyo, but no performance or construction data were given.

Current Production Estimated

Nevertheless, in view of previous expansion, the ambitious program of the War Planning Board and the exigencies of the war itself, it is believed that the present maximum capacity of Japan is probably around 20,000 aircraft a year.

To prove this statement, let us examine briefly the Japanese aircraft industry itself together with industries indispensable to airplane production.

Japan imported her first airplanes in 1917 when the Army bought machines in Europe. She has continued to import planes since then. At the same time, efforts have been constantly made to produce them at home in both state and private factories. Although the Japanese have shown little originality and creative power, they have succeeded in building up an industry of high efficiency and a standard far superior to their automobile industry. Japanese airplanes have, especially in more recent years, shown good performance even when measured by European and American standards.

While in earlier years Japanese constructors were mainly influenced by British (Sopwith) and French models, in the years after 1933 Germany became their source of inspiration. The Mitsubishi T 96, for instance, was developed from the German Junkers 86. This craft is still in use as a naval and coastal defense bomber and has proved successful as such.

Afterwards, the influence of American designers became preponderant. Quite a number of American machines were bought for commercial and military use. This is shown by import figures, for four years as follows:

1940 (first 6 mo only)……2,574,000

Regardless of where the airplanes came from, the Japanese learned from all of them and sometimes developed them in a direction quite different from the original with regard to range, load, speed, etc. Generally, the Japanese seem to favor a lower wing loading and higher aspect ratio than either the British or German designers.

There is no doubt that Japan has profited from experiences of the second World War in addition to receiving aircraft from Italy and Germany. Probably more important were the reports of military and technical observers on the spot. Her own aircraft industry was already well developed in 1936; imports do not seem to have played an important part with regard to numbers, and were probably more than balanced by Japanese exports. In fact, China's purchases from the United States were more important than those of Japan in the period from 1936 to 1940.

Government Controls Industry

Most of the Japanese aircraft factories were started by the larger ship-building firms which, through their experiences had, so to speak, a flying start. In 1938 the Airplane Manufacturing Industry Law was passed by the Diet with the object of improving quality and reducing production costs. This law gave the government practically full control over the industry, which became subject to a license system. It can be assumed that the industry has, under this law, concentrated upon production of seasoned models which are being turned out on as large a scale as possible.

An Aircraft Technical Committee was set up to standardize parts and materials. Qualified manufacturers were exempted from income and profits taxes on new undertakings, were permitted to import, duty free, equipment and materials not obtainable in Japan and were allowed to issue debentures up to twice their paid-up capital. Fourteen companies were so licensed in 1938 and one in 1939.

To make the Japanese aircraft industry independent of foreign research and models, several research institutions have been created, eg, the Army Aeronautical Institute, the Naval Aviation Arsenal, the Aeronautic Institute of Tokyo Imperial University and the Central Aeronautical Institute. The last-mentioned was established in April, 1939, to carry out an exhaustive five- year research program to cost 50 million yen. It was to devote its attention to the manufacture of high speed aircraft, large-sized passenger aircraft (troop-carrying planes?) and the increase in production of superior types.

Japan possesses an important engine producing capacity, though details with regard to engines built are scarce. Among the models were Wright, Pratt & Whitney, Rolls-Royce, Napier, Fiat, Renault and Hispano-Suiza. The government has, during recent years, encouraged the production of engines as well as machinery and tools, with the result that between 1936 and 1938 that production doubled in value. If one uses the machinery and tool production increase rate of 1936-38 as being applicable to the production of airplane engines, and applies it to the known 1936 output, we get a 1937 engine production figure of 10,000 engines and 15,000 for 1938. A faster rate of increase would, however, be necessary to reach the Board of Planning goal of 40,000 engines per year at the end of 1941.

Although production figures have not been published since 1938 it can be assumed the rate of increase has been large to meet the government program to become independent of imports in most respects. The talent of the Japanese for copying foreign products and producing them on a large scale, once they have grasped the technical problems, has certainly helped them to achieve the sought-for independence.

While the change from manufacturing textiles to the heavy industries was already pronounced during the first half of the last decade, it has been accelerated by the Four-Year Plan of 1939 which had as its purpose obtaining self-sufficiency by 1942 within the Yen-Bloc in iron and steel, coal, light metals, zinc, soda, sulphate of ammonia, pulp, rolling stock, motor cars, shipping and substantial increases in many other raw materials. This list does not contain aircraft, tanks, guns and ammunition, but in a nation like Japan it goes without saying that the aim of the whole plan has been to become independent in the production of war materials. It should be emphasized that this development was achieved while a major campaign was being fought in China, and that it does not seem to have been hampered to any considerable extent by that campaign.

With regard to light metals, it should be noted that Japan was self-sufficient in production of magnesium as far back as 1935. Nevertheless, to meet the growing demand of armaments, the program of 1939 foresaw an increase of 1,000 percent within four or live years.

The position of aluminum, the most important metal in aircraft production, is obscured by the fact that production figures are not available since 1937, when home production amounted to 14,000 tons. Import figures were, for strategical reasons, not published. For the previous year, however, the ratio of home production to import was 40.5 to 59.5. If we take the same proportion for 1937, this would mean about 21,000 tons were imported although some estimates put imports between 10 and 15,000 tons.

For her home production Japan used mostly alunite or alum stone from southern Korea and bauxite from Greece and the Dutch East Indies. The increasing demand can be judged from quantities previously imported from the Dutch East Indies and the percentage they represent of DEI bauxite exports:

YearMetric tons

In addition, Japan imported 28,000 tons of aluminum metal from Canada, the United States and Norway in 1939.

In 1940, a deposit of aluminum shale was discovered in the Hiroshima Prefecture, and several companies are producing aluminum exclusively from this shale, although such metal is said to be inferior in quality to that produced from bauxite.

There appear to be important bauxite deposits in the Palau group of the Japanese mandated islands. They are estimated by Japanese authorities to contain some ten million tons. The purity of the ore is said to be very high, and Japan hopes to be able to cover about 75 percent of her requirements with bauxite from Palau with the rest coming from shale in Manchukuo.

Although Japan has at present no possibilities of importing any aluminum metal from abroad, her position does not seem serious in this respect. Not only can she have accumulated considerable reserves of the metal during the last few years, but she is also able to increase her own production, using her own less economic raw materials.

Has Adequate Power

There is no question that she has the electric power necessary, production of which is estimated at from 30 to 32 milliard kwh annually. Since 50,000 tons of aluminum need some 1,400,000 kwh, she thus has power for some 100,000 tons of aluminum and 5,000 tons of magnesium. Allowing six tons of aluminum per bomber; half a ton for fighters and less for trainers, Japan has enough for 20,000 to 25,000 planes per year.

The Japanese aircraft industry may, like others, experience ten1porary production difficulties through foreseen or unforeseen bottlenecks, but serious reduction in output owing to such causes is not probable. On the contrary, as long as the Japanese islands remain undisturbed, production will probably increase. Therefore, the reduction of Japanese aircraft production will be one of the immediate strategic aims, once the Allies are able to take the offensive against Japan and provided they possess air bases not too far away.

Apart from the bombing of the important industrial plants, the bombing of ports and shipping will have the utmost effect. Japan, like Great Britain, has to rely upon imports, especially for the feeding of her industrial machine. Most of the required materials come from Manchukuo, Korea, occupied China, the Japanese mandates and perhaps French Indo-China, Thailand and other such territories as Japan might have conquered. To disrupt her lifelines, to destroy her ports, means disaster for her industrial and consequently her military machine.

This article was originally published in the September, 1942, issue of Aviation magazine, vol 41, no 9, pp 94-97, 317-318.
The original article includes 8 photos.
Photos are not credited.