The Hiro H4H (or Hiro Navy Type 91 Flying Boat) was a 1930s

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

ese bomber or reconnaissance monoplane flying boat designed and built by the

Hiro Naval Arsenal The Hiro Naval Arsenal (''Hiro Kaigun Kōshō'' or ''Dai-Jūichi Kaigun Kōkū-shō'' (11th Naval Arsenal), often abbreviated as ''Hiroshō'') at Kure (呉), Hiroshima prefecture, was a production facility for seaplanes, flying boats, and aero engi ...

for the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

Design and development

First appearing in 1931 the H4H1 was a twin-engined high-wing monoplane flying-boat. Powered by two 500 hp (597 kW) Hiro 91-1 engines strut-mounted above the wing it was produced by the Kawanishi company and entered service in 1933. An improved version of the design, the H4H2, followed into production two years later. The H4H2 has re-designed twin fins and rudders and was powered by two 800 hp (597 kW) Myojo radial engine. A total of 47 of both versions was produced. Both the H4H1 and H4H2 remained in front-line naval service through the 1930s.

Variants

;H4H1 (Hiro Navy Type 91 Model 1 Flying Boat) :Variant powered by two 500hp (597kW) Hiro 91-1 engines. ;H4H2 (Hiro Navy Type 91 Model 2 Flying Boat) :Variant powered by two 800hp (597kW) Myojo radial engines.

Operators

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Imperial Japanese Navy Air Service The was the Naval aviation, 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 their first air ...

Specifications (H4H2)

References

Notes

Bibliography

* {{Japanese Navy short aircraft designations 1930s Japanese patrol aircraft World War II Japanese patrol aircraft Flying boats High-wing aircraft H4H Twin piston-engined tractor aircraft