The Kawanishi H8K is a

flying boat A flying boat is a type of seaplane with a hull, allowing it to land on water. It differs from a floatplane in having a fuselage that is purpose-designed for flotation, while floatplanes rely on fuselage-mounted floats for buoyancy. Though ...

used by the

Imperial Japanese Navy Air Service The (IJNAS) was the air arm of the Imperial Japanese Navy (IJN). The organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War. The Japanese military acquired its first aircraft in ...

during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

for

maritime patrol Maritime patrol or maritime reconnaissance is the task of monitoring areas of water. Generally conducted by military and law enforcement agencies, maritime patrol is usually aimed at identifying human activities. Maritime patrol refers to active ...

duties. The Allied reporting name for the type was "Emily". The Kawanishi H8K was a large, four-

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...

aircraft designed for long

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

and extended endurance on patrols or bombing missions typically flown alone over the

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

. The

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototype ...

first flew in January 1941, and H8K1s made their first combat

sortie A sortie (from the French word meaning ''exit'' or from Latin root ''surgere'' meaning to "rise up") is a deployment or dispatch of one military unit, be it an aircraft, ship, or troops, from a strongpoint. The term originated in siege warf ...

in March 1942. The robust H8K2 "Emily" flying boat was also fitted with powerful defensive armament, for which

Allied An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not an explicit agreement has been worked out among them. Members of an alliance are calle ...

pilots had substantial respect wherever this aircraft was encountered in the

Pacific theater The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the continen ...

. Aircraft historian René Francillon called the H8K "the most outstanding water-based combat aircraft of the Second World War."

Design and development

At the same time the type's predecessor, the

Kawanishi H6K The Kawanishi H6K was an Imperial Japanese Navy flying boat produced by the Kawanishi Aircraft Company and used during World War II for maritime patrol duties. The Allied reporting name for the type was Mavis; the Navy designation was . Develo ...

, was entering service in 1938 the

Navy A navy, naval force, military maritime fleet, war navy, or maritime force is the military branch, branch of a nation's armed forces principally designated for naval warfare, naval and amphibious warfare; namely, lake-borne, riverine, littoral z ...

ordered the development of a larger, longer-ranged patrol aircraft under the designation Navy Experimental 13-''Shi'' Large-size Flying Boat. The result was a large, shoulder-winged design that is widely regarded as the best flying boat of the war. Despite this, initial development was troublesome, with the prototype displaying terrible handling on the water. Deepening of the

hull Hull may refer to: Structures * The hull of an armored fighting vehicle, housing the chassis * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a sea-going craft * Submarine hull Ma ...

, redesigning of the planing bottom and the addition of spray strips under the nose rectified the water handling problems. Two further

s — actually pre-production aircraft — joined the development program in December 1941. The

IJNAS The (IJNAS) was the air arm of the Imperial Japanese Navy (IJN). The organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War. The Japanese military acquired its first aircraft in ...

accepted the first production version as the H8K1, Navy Type 2 Flying Boat, Model 11, of which 14 would be built. The improved H8K2 variant soon appeared, and its extremely heavy defensive armament earned it deep respect among

aircrew Aircrew are personnel who operate an aircraft while in flight. The composition of a flight's crew depends on the type of aircraft, plus the flight's duration and purpose. Commercial aviation Flight deck positions In commercial aviatio ...

s. The H8K2 was an upgrade over the H8K1 with more powerful engines, slightly revised armament, and an increase in fuel capacity. This was to be the definitive variant, with 112 produced. 36 examples of a dedicated transport version, the H8K2-L, were also built, capable of carrying 62 troops. This aircraft was also known as ''Seikū'' (晴空, "Clear Sky"). The side defensive blisters, ventral defensive hatch, and dorsal

turret Turret may refer to: * Turret (architecture), a small tower that projects above the wall of a building * Gun turret, a mechanism of a projectile-firing weapon * Optical microscope#Objective turret (revolver or revolving nose piece), Objective turre ...

were discarded. To increase the available space within the aircraft its hull tanks were removed, thus reducing its

Operational history

The H8K entered production in 1941 and first saw operational use on the night of 4 March 1942 in a second raid on Pearl Harbor. Since the target lay out of

for the flying boats, this audacious plan involved a refuelling by

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

French Frigate Shoals The French Frigate Shoals (Hawaiian language, Hawaiian: Kānemilohai) is the largest atoll in the Northwestern Hawaiian Islands, located about northwest of Honolulu, Hawaii, Honolulu. Its name commemorates France, French explorer Jean-Fran ...

, some north-west of

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, ''en route''. Two planes from the Yokohama Kōkūtai (Naval Air Corps) attempted to bomb Pearl Harbor but, due to poor visibility, did not accomplish any significant damage. Six days after the second Pearl Harbor raid, one of the "Emilys" was sent on a daylight photo-reconnaissance mission of

Midway Atoll Midway Atoll (colloquialism, colloquial: Midway Islands; ; ) is a atoll in the North Pacific Ocean. Midway Atoll is an insular area of the United States and is an Insular area#Unorganized unincorporated territories, unorganized and unincorpo ...

. It was intercepted by radar-directed

Brewster F2A Buffalo The Brewster F2A Buffalo is an American fighter aircraft which saw service early in World War II. Designed and built by the Brewster Aeronautical Corporation, it was one of the first U.S. monoplanes with an arrestor hook and other modificatio ...

fighters of Marine Fighting Squadron 221 (

VMF-221 Marine Fighting Squadron 221 (VMF-221) was a Marine Forces Reserve, reserve fighter squadron of the United States Marine Corps. Originally commissioned during the World War II, it flew the Brewster F2A-3, and after reconstitution in 1943, the F ...

) and shot down. All aboard were killed, including Lt. Hashizume Hisao, the lead pilot of the second Pearl Harbor raid. H8K2s were used on a wide range of

patrol A patrol is commonly a group of personnel, such as law enforcement officers, military personnel, or security personnel, that are assigned to monitor or secure a specific geographic area. Etymology The word "patrol" is derived from the Frenc ...

reconnaissance In military operations, military reconnaissance () or scouting is the exploration of an area by military forces to obtain information about enemy forces, the terrain, and civil activities in the area of operations. In military jargon, reconnai ...

bombing A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechan ...

, and

transport Transport (in British English) or transportation (in American English) is the intentional Motion, movement of humans, animals, and cargo, goods from one location to another. Mode of transport, Modes of transport include aviation, air, land tr ...

missions throughout the

Pacific War The Pacific War, sometimes called the Asia–Pacific War or the Pacific Theatre, was the Theater (warfare), theatre of World War II fought between the Empire of Japan and the Allies of World War II, Allies in East Asia, East and Southeast As ...

Variants

Famous Airplanes of the World (1994), pp. 19–22.The Maru Mechanic (1979), pp. 71–73.Model Art (1999), pp. 61–69.https://www.airvectors.net/avh6kh8k.html ;H8K1 ''Experimental Type 13 Large-sized Flying boat'' (13試大型飛行艇 ''13-Shi Ōgata Hikōtei'') : One prototype and four supplementary prototypes. Prototype was mounted Mitsubishi Mk4A Kasei 11 engines, supplementary prototype was mounted Mitsubishi MK4B Kasei 12 engines. Supplementary prototypes were renamed ''Type 2 Flying Boat Model 11'' on 5 February 1942. Prototype was rebuilt to H8K1-L in November 1943. ;H8K1 ''Type 2 Flying boat, Model 11'' (二式飛行艇11型 ''Nishiki Hikōtei 11-gata'') :Developed on 5 February 1942. First operative model of series, 12 produced. Mounted Mitsubishi MK4B Kasei 12 engines. ;;H8K1-L ''Type 2 Transport Flying Boat'' (二式輸送艇 ''Nishiki Yusōtei'') :Rebuilt from H8K1 prototype. Fitted augment exhausts. Up to 41 passengers. ;H8K2 ''Type 2 Flying boat, Model 12'' (二式飛行艇12型 ''Nishiki Hikōtei 12-gata'') :Developed on 26 June 1943. Mounted Mitsubishi MK4Q Kasei 22 engines and improved tail gun turret. Latter batch was equipped with Air-Surface Vessel (ASV) search radar, and removed side gun blisters. 112 produced. ;;H8K2-L ''Seikū'' ("Clear Sky")'', Model 32'' (晴空32型 ''Seikū 32-gata'') :Transport version of H8K2. Initial named ''Type 2 Transport Flying Boat, Model 32''. Armaments were 1 × forward-firing 20 mm cannon and 1 × rearward-firing 13 mm machine gun. Up to 64 passengers. ;H8K3 ''Provisional name Type 2 Flying Boat, Model 22'' (仮称二式飛行艇22型 ''Kashō Nishiki Hikōtei 22-gata'') :Experimental version, H8K2 modified. Equipped with retractable floats in wingtips, Fowler flaps, sliding hatch side gun locations in place of the blisters and a retractable dorsal turret, all in an effort to increase speed; two prototypes only (work number 596 and 597). ;H8K4 ''Provisional name Type 2 Flying Boat, Model 23'' (仮称二式飛行艇23型 ''Kashō Nishiki Hikōtei 23-gata'') :H8K3 re-engined with 1,825 hp MK4T

Mitsubishi Kasei The was a two-row, 14-cylinder air-cooled radial engine built by Mitsubishi Heavy Industries and used in a variety of World War II Japanese aircraft, such as Mitsubishi J2M and Mitsubishi G4M. The Mitsubishi model designation for this engi ...

25b engines, two converted from H8K3. ;;H8K4-L ''Provisional name Seikū, Model 33'' (仮称晴空33型 ''Kashō Seikū 33-gata'') :Transport version of H8K4. Abandoned due to priority being given to fighters for home island defense, so no more H8Ks were being produced. ;G9K :Proposed land-based attack bomber variant, only a project.

Operators

;

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Famous Airplanes of the World (1994), each pages. *

** Saeki ''Kōkutai'' ** Sasebo ''Kōkutai'' ** Takuma ''Kōkutai'' ** Yokohama ''Kōkutai'' ** Yokosuka ''Kōkutai'' ** 14th ''Kōkutai'' ** 801st ''Kōkutai'' ** 802nd ''Kōkutai'' ** 851st ''Kōkutai'' ** 901st ''Kōkutai'' ** 902nd ''Kōkutai'' ** 951st ''Kōkutai'' ** 1001st ''Kōkutai'' ** 1021st ''Kōkutai'' ** 1081st ''Kōkutai'' *Miscellaneous **

Yokosuka Naval District was the first of four main administrative districts of the pre-war Imperial Japanese Navy. Its territory included Tokyo Bay and the Pacific Ocean, Pacific coasts of central and northern Honshū from the Kii Peninsula to Shimokita Peninsula. Its h ...

** 11th Naval Air Arsenal **

11th Air Fleet The was a grouping of naval aviation and surface units. Assignments and Components Commanders Chiefs of Staff Notes References * {{Use dmy dates, date=June 2017 Fleets of the Imperial Japanese Navy Units of the Imperial Japanese N ...

Kamikaze , officially , were a part of the Japanese Special Attack Units of military aviators who flew suicide attacks for the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, intending to d ...

**Azusa group (picked from 801st ''Kōkutai'', guidance only)

Surviving aircraft

Four aircraft survived until the end of the war. One of these, an H8K2 (work number 426), was captured by

U.S. The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous ...

forces at the end of the war and was evaluated before being eventually returned to Japan in 1979. It was on display at

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

Museum of Maritime Science The Museum of Maritime Science (船の科学館, ''Fune-no-kagakukan'') is a marine science museum located in Higashiyashio, Shinagawa, Tokyo on Odaiba island, Japan. In 2011 the museum announced to cease the most parts of its operation for ren ...

until 2004, when it was moved to Kanoya Air Base Museum at Kanoya Air Field in

Kagoshima , is the capital Cities of Japan, city of Kagoshima Prefecture, Japan. , the city had an estimated population of 583,966 in 285,992 households, and a population density of 1100 persons per km2. The total area of the city is . Etymology While the ...

. The submerged remains of an H8K can be found off the west coast of

Saipan Saipan () is the largest island and capital of the Northern Mariana Islands, an unincorporated Territories of the United States, territory of the United States in the western Pacific Ocean. According to 2020 estimates by the United States Cens ...

, where it is a popular

scuba diving Scuba diving is a Diving mode, mode of underwater diving whereby divers use Scuba set, breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The word ''scub ...

attraction known erroneously as the "B-29", or the "Emily". Another wrecked H8K lies in Chuuk Lagoon, Chuuk, in Micronesia. This aircraft is located off the south-western end of Dublon Island.

Specifications (Kawanishi H8K2)

References

Notes

Bibliography

* Francillon, René J. ''Japanese Aircraft of the Pacific War''. London: Putnam & Company, 1970 (2nd edition 1979). . * * * * * * * *Famous Airplanes of the World, No. 49 ''Type 2 Flying Boat'', Bunrindō (Japan), November 1994. *The Maru Mechanic, No. 19 ''Feature, Type 2 Flying Boat'', Ushio Shobō (Japan), November 1979. * Model Art No. 541, Special issue ''Type 2 Flying Boat and Imperial Japanese Navy Flying Boats'', Model Art Co. Ltd., July 1999. {{DEFAULTSORT:Kawanishi H8k H8K H8K, Kawanishi Flying boats Four-engined tractor aircraft Shoulder-wing aircraft Aircraft first flown in 1941 Four-engined piston aircraft