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Imperial Japanese Navy Air Service

The Imperial Japanese Navy Air Service (Japanese:" 海軍航空本部, Dai-Nippon Teikoku Kaigun Koku Hombu) was the air branch of the Imperial Japanese Navy during World War II responsible for the aircrafts.

It was controlled by the Navy Staff of the Imperial Japanese Navy and the Navy Ministry. The Imperial Japanese Navy Air Service was equal in function to the Royal Navy's Fleet Air Arm (FAA), the U.S. Navy's Naval Aviation branch, the Italian Navy's Aviazione Ausiliara per la Marina, or the Soviet Navy's Morskaya Aviatsiya.

The Imperial Japanese Navy Aviation Bureau (Kaigun Koku Hombu) of the Ministry of the Navy of Japan was responsible for the development and training.

The Japanese military acquired their first aircraft in 1910 and followed the development of air combat during World War I with great interest. They initially procured European aircraft but quickly built their own and launched themselves onto an ambitious aircraft carrier building program. They launched the world's first purpose-built aircraft carrier, Hōshō, in 1922. Afterwards they embarked on a conversion program of several excess battlecruisers and battleships into aircraft carriers. The IJN Air Service had the mission of national air defence, deep strike, naval warfare, and so forth. It retained this mission to the end.

The Japanese pilot training program was very selective and rigorous, producing a high-quality and long-serving pilot corps, who ruled the air in the Pacific during early World War II. However, this program, and a shortage of gasoline for training, did not allow the Navy to rapidly provide qualified replacements in sufficient numbers. Moreover, the Japanese, unlike the U.S. or Britain, proved incapable of altering the program to speed up training of the recruits they got. The resultant decrease in quantity and quality, among other factors, resulted in increasing casualties toward the end of the war.

Japanese navy aviators, like their Army counterparts, preferred manueuverabile aircraft, leading to lightly-built but extraordinarily agile types, most famously the A6M, which achieved its feats by sacrificing armor and self-sealing fuel tanks.

History

Origins

In 1912, Royal Navy had informally established its own flying branch — Royal Naval Air Service. The Japanese admirals, whose own Navy had been modeled on the Royal Navy and who they admired, themselves proposed their own Naval Air Service. The Japanese Navy had also observed technical developments in other countries and saw that the airplane had potential. The following year, in 1913 a Navy transport ship, the Wakamiya was converted into a seaplane tender, a number of aircraft were also purchased.

Siege of Tsingtao

On 23 August 1914, as a result of its treaty with Great Britain, Japan declared war on Germany. The Japanese, together with a token British force, then laid siege to the German held territory of Kiaochow and its administrative capital Tsingtao on the Shandong peninsula. During the siege, starting from September, Maurice Farman seaplanes onboard (two active and two reserve) the Wakamiya conducted reconnaissance and aerial bombardments on German positions and ships. On September 30 the Wakamiya was later damaged by a mine on, but the seaplanes(by transferring to land) continued to used against the German defenders until their surrender on November 7, 1914. The Wakamiya conducted the world's first naval-launched aerial raids in history and was in effect the first aircraft carrier of the Imperial Japanese Navy. By the end of the siege the aircraft had conducted 50 sorties and dropped 200 bombs, although damages to German defenses were light.

Interwar Years

The Japanese navy had closely monitored the progress of aviation of the three Allied naval powers during World War I and concluded that Britain had made the greatest advances in naval aviation

The Sempill Mission was a British aeronaval technical mission led by Captain Sempill and sent to Japan in September 1921, with the objective of helping the Imperial Japanese Navy develop its aeronaval forces. The mission consisted in a group of 29 instructors, headed by Captain Sempill, and stayed in Japan for 18 months. It provided the Japanese navy with a quantum leap in aviation training and technology

The Japanese were trained on several new aircraft, such as the Gloster Sparrowhawk, in various techniques such as torpedo bombing and flight control. The Mission also brought the plans of the most recent British aircraft carriers, such as the HMS Argus and the HMS Hermes, which influenced the final stages of the development of the carrier Hōshō. The Hōshō became the first designed aircraft carrier from the keel up to be built.

Under the Washington Naval Treaty two incomplete battlecruisers were allowed to be rebuilt as carriers, for the Japanese; the Akagi and the Amagi. However the Amagi was damaged during an earthquake in 1923 and the Kaga became a replacement. With these two carriers the much of Imperial Japanese Navys' doctrines and operating procedures were established.

IJNAS vs US first encounter (1932)

During the Shanghai Incident on February 22, 1932 Lt Robert Short (US Army Reserve) while piloting a Boeing 218 with Chinese markings damaged one IJNAS Type 13 carrier attack aircraft, killing the pilot, Lt. Kotani and wounding the observer, before he was killed in action. Reportably three days previously Short had shot down IJNAS Lt. Kidokoro.

Sino-Japanese War

From 1937 the Imperial Japanese Navy Air Service was involved in China. Aircraft from carriers attack Chinese positions in Shanghai and surrounding areas, naval bombers such as the G3M and G4M were used to bomb Chinese cities and fighter aircraft and naval fighter were used to again air superiority. Unlike other naval airforces, the IJNAS was responsible strategic bombing and operated long ranged bombers.

The Japanese strategic bombing were mostly done against Chinese big cities, such as Shanghai, Wuhan and Chonging, with around 5 000 raids from February 1938 to August 1943.

The bombing of Nanjing and Guangzhou, which began on 22 and 23 September 1937, called forth widespread protests culminating in a resolution by the Far Eastern Advisory Committee of the League of Nations. Lord Cranborne, the British Under-Secretary of State For Foreign Affairs, expressed his indignation in his own declaration.

Words cannot express the feelings of profound horror with which the news of these raids had been received by the whole civilized world. They are often directed against places far from the actual area of hostilities. The military objective, where it exists, seems to take a completely second place. The main object seems to be to inspire terror by the indiscriminate slaughter of civilians...»

World War II

At the beginning of the Pacific war the Navy Air Service consisted of five fleets In April, 1941 the First Air Fleet was created, concentrating the Navy's carriers into a single powerful striking unit The Japanese had a total of six fleet carriers and three smaller carriers. The 11th Airfleet contained most of the Navy's land based strike aircraft.

On December 7, 1941, the Imperial Japanese Navy attacked Pearl Harbor crippling the U.S Pacific Fleet and destroying over 188 aircraft for a loss of 29 aircraft. On December 10, land based bombers of the 11th Airfleet were also able to sink H.M.S Prince of Wales and H.M.S Repulse.

There were also air raids on the Philippines and on attacks Darwin in northern Australia.

From 16 December 1941 to 20 March 1945 IJN aviation casualites killed were 14,242 aircrew and 1,579 officers.

Aircraft strength 1941

The IJN had over 3,089 aircraft in 1941 and 370 trainers.

1,830 first line aircraft including:

660 fighters, mostly Mitsubishi Zeros
330 Carrier based strike aircraft
240 twin engined bombers
520 seaplanes and flying boats.

Organisation

Carrier aviation flotillas

The elite of the pilots were the carrier-based air groups (kokutai, later called koku sentai) whose size (from a handful to 80 or 90 aircraft) was dependent on both the mission and type of aircraft carrier that they were on. Fleet carriers had three types of aircraft: fighters, level/torpedo planes, and dive bombers. Smaller carriers tended to have only two types, fighters and dive bombers. The carrier-based kokutai numbered over 1,500 pilots and just as many aircraft at the beginning of the Pacific War.

Eleventh Air Fleet land-based air fleets

The IJN also maintained a shore-based system of air fleets called Koku Kantai and area air fleets called homen kantai containing mostly twin-engine bombers and seaplanes. The senior command was the Eleventh Air Fleet, commanded by Vice Admiral Nihizo Tsukuhuru. Land based aircarft provided the bulk of Japan's naval aviation up to the eve of World War II.

Strength

Each air fleet contained one or more air flotillas (commanded by Rear Admirals) each with two or more air groups. Each air group consisted of a base unit and 12 to 36 aircraft, plus four to 12 aircraft in reserve. Each air group consisted of several hikotai (squadron/s) of nine, 12 or 16 aircraft; this was the main IJN Air Service combat unit and was equivalent to a chutai in the Imperial Japanese Army Air Service Each hikotai was commanded by a Lieutenant (j.g.), Warrant Officer, or experienced Chief Petty Officer, while most pilots were non-commissioned officers. There were usually four sections in each hikotai, and each section (shotai) with three or four aircraft; by mid-1944 it was common for a shotai to have four aircraft. There were over 90 air groups at the start of the Pacific War, each assigned either a name or a number. The named air groups were usually linked to a particular navy air command or a navy base. They were usually numbered when they left Japan.

Air Group identification

Air Groups 200 to 399 - Fighter groups.
Air Groups 400 to 499 - Float planes
Air Groups 600 to 699 - mixed aircraft types.

Naval Aircraft identification System

The IJN had an aircraft designation system similar to that used by the U.S. Navy from 1922 until 1962. Each new design was given a "short designation" consisting of a group of Roman letters and numbers.

The first letter (sometimes two) indicated the basic type or purpose of the aircraft.
Second came a series number indicating the number of major sub-types produced by that manufacturer. (Unlike USN practice, the digit "1" was not ignored in this system and was included.)
Third was the second letter which was the manufacturer's code, and included some non-Japanese companies.

(G4M designated attack bomber (G), the fourth in the Navy's sequence, designed or produced by Mitsubishi, while G5M would be the next attack bomber in sequence, not necessarily just the next Mitsubishi type.)

Letter	Type	Manufacturer
A	Carrier Fighter	Aichi (Aichi Tokei Denki and Aichi Kokuki)/North American Aviation (US)
B	Carrier Attack Bomber (Torpedo or Level Bomber)	Boeing Aircraft (US)
C	Reconnaissance(land-based)	Consolidated Aircraft (US)
D	Carrier Bomber (Dive Bomber)	Douglas Aircraft (US)
E	Reconnaissance Seaplane	-
F	Observation Seaplane	-
G	Attack Bomber	Hitachi Kokuki/Grumman Aircraft Engineering (US)
H	Flying Boat(Reconnaissance)	Hiro (Dai-Juichi Kaigun Koskusho)/Hawker Aircraft (UK)
He	-	Ernst Heinkel Flugzeugwerke (Germany)
J	Land-based Fighter	Nihon Kogata Hikoki/Junkers Flugzeug und Moterenwerke (Germany)
K	Trainer	Kawanishi Kokuki
L	Transport	-
M	Special Floatplane	Mitsubishi Jukogyo
MX	Special Purpose Aircraft	-
N	Fighter Seaplane	Nakajima Hikoki
P	Bomber(land based)	Nihon Hikoki
Q	Patrol Plane	-
R	Land-based Reconnaissance	-
S	Night Fighter	Sasebo (Dai-Nijuichi Kaigun Kokusho)
Si	-	Showa Hikoki
V	-	Vought-Sikorsky (US)
W	-	Watanabe Tekkosho/Kyushu Hikoki
Y	-	Yokosuka (Dai-Ichi Kaigun Koku Gijitsusho)
Z	-	Mizuno Guraida Seisakusho

Minor to moderate changes in the design (usually reflected in a new Type Model number) were indicated by adding a second subtype number after the manufacturer's letter.

Further minor changes were indicated by adding letters after the subtype number as in the Type/Model scheme above. The first two letters and the series number remained the same for the service life of each design.

In a few cases, when the designed role of an aircraft changed, the new use was indicated by adding a dash and a second type letter to the end of the existing short designation (e.g., the H6K4 was the sixth flying boat (H6) designed by Kawanishi (K), fourth version of that design (4). When the plane was equipped primarily as a troop or supply transport, its designation was H6K4-L.)

Notes

References

Stille, Mark(2005). Imperial Japanese Navy Aircraft Carriers 1921-45. Osprey Publishing ISBN 1-84176-853-7
Tagaya, Osamu(2003). Imperial Japanese Navy Aviator 1937-45. Osprey Publishing ISBN 1-84176-385-3
Peattie, Mark R(2007). Sunburst: The Rise of Japanese Naval Air Power, 1909-1941. Naval Institute Press ISBN 978-1591146643

External links

http://www.combinedfleet.com/kaigun.htm (see the section of Japanese Navy Aircraft)
http://www.warbirdpix.com/ (link with somes photos of Axis Aircraft (German, Italian and Japanese Army and Navy)
http://www.j-aircraft.org/xplanes/ (about advanced Japanese Army and Navy aircraft)
http://uk.geocities.com/sadakichi09/ (over Japanese Navy and Army armaments, vehicles, Aircraft, electronic warfare and somes local special Japanese weapon technology )
http://www.j-aircraft.com/captured/ (somes captured aircraft or aircraft in evaluations)
http://www.j-aircraft.com/ (general resources of Japanese aircraft)