The Nakajima G5N ''Shinzan'' (, "Deep Mountain") was a four-engined long-range

heavy bomber Heavy bombers are bomber aircraft capable of delivering the largest payload of air-to-ground weaponry (usually bombs) and longest range (takeoff to landing) of their era. Archetypal heavy bombers have therefore usually been among the larges ...

designed and built 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 ...

prior to

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. The Navy designation was "Experimental 13-Shi Attack Bomber"; the Allied code name was "Liz".

Design and development

The Nakajima G5N ''Shinzan'' originated due to the Imperial Japanese Navy's interest in developing a long-range attack bomber capable of carrying heavy loads of bombs or torpedoes a minimum distance of . To meet this requirement, it became apparent a four-engine lay-out would be necessary. As Japanese aircraft manufacturers lacked experience in building such large complex aircraft, the Navy was forced to search for a suitable existing foreign-made model upon which to base the new design. It settled on the American

Douglas DC-4E The Douglas DC-4E was an American experimental airliner that was developed before World War II. The DC-4E never entered production due to being superseded by an entirely new design, the Douglas DC-4/C-54, which proved very successful. Many of t ...

airliner An airliner is a type of aircraft for transporting passengers and air cargo. Such aircraft are most often operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an ...

. In 1939 the sole prototype of this airliner (previously rejected by American airline companies) was purchased by Nippon Koku K.K. (Japan Airlines Co) and clandestinely handed over to the

Nakajima Aircraft Company The was a prominent Japanese aircraft manufacturer and aviation engine manufacturer throughout World War II. It continues as the car and aircraft manufacturer Subaru. History The Nakajima Aircraft company was Japan's first aircraft manufacture ...

for dismantling and inspection. The design that emerged from this study was for an all-metal mid-wing

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

with fabric-covered control surfaces and powered by four 1,870 hp Nakajima NK7A Mamori 11 air-cooled radial engines driving four-bladed propellers. A long ventral bomb-bay, glazed nose and twin tailfins replacing the DC-4E's distinctive triple rudder were included. The DC-4E's retractable

tricycle undercarriage Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle ge ...

was retained, as well as the original wing form and powerplant arrangement. Defensive armament comprised two 20mm Type 99 Model 1 cannon (one in a power-operated dorsal and one in a tail turret), plus single-mount hand-operated 7.7mm

Type 92 machine gun The was developed for aerial use for the Imperial Japanese Navy in 1932. The Type 92 is a light machine gun and not to be confused with the similarly named Type 92 heavy machine gun. Description It was the standard hand-held machine gun in mul ...

s in the nose, ventral and waist positions. The first prototype G5N1 made its maiden flight on 14:35 8 April 1941. Overall performance proved disappointingly poor however, due to a combination of excessive weight, the unreliability of the Mamori engines and the complexity of the design. Only three more prototypes were completed. In an attempt to salvage the project, two additional airframes were fitted with 1,530 hp Mitsubishi MK4B 12 "Kasei" engines and redesignated G5N2s. Although the Mitsubishi engines were more reliable than the original Mamori 11s, the aircraft was now even more hopelessly underpowered and further development of the type was halted.

Operational history

Of the six completed ''Shinzans'', four were relegated for use as long-range Navy transports under the designation G5N2-L Shinzan-Kai Transport. The Allies allocated the code-name "Liz" to the aircraft, in the expectation it would be used as a bomber.

Variants

;G5N1 ''Experimental Type 13 Land-based Attack Bomber "Shinzan"'' ( ''13-Shi Rikujō Kōgekiki "Shinzan"''): Prototype, two built. Initial named ''Experimental Type 13 Large-size land-based Attack Bomber'' ( ''13-Shi Ōgata Rikujō Kōgekiki''). Four-engined

torpedo bomber A torpedo bomber is a military aircraft designed primarily to attack ships with aerial torpedoes. Torpedo bombers came into existence just before the First World War almost as soon as aircraft were built that were capable of carrying the weight ...

. Three-blade propeller, mounted four Mitsubishi MK4B Kasei 12 (1,530 hp) radial engines. ;G5N2 ''Test production "Shinzan Kai"'' ( ''Shisei "Shinzan Kai"''): Supplementary prototype, four built. Four-blade propeller, mounted four Nakajima NK7A Mamori 11 (1,870 hp) radial engines. All G5N2s were rebuilt to G5N2-L in 1943. ;G5N2-L ''"Shinzan Kai" Freighter'' ( ''"Sinzan Kai" Yusōki''): Long-range Navy transport conversion. All G5N2-Ls were deployed to 1021st ''Kōkutai'', Katori Air Base. ;Nakajima Ki-68: Proposed Army bomber prototype version of the G5N1. Engines were planned Mitsubishi Ha-101, Ha-104, Ha-107, Nakajima Ha-39 or Ha-103 engines. Discontinued in 1941. ;Kawasaki Ki-85: Proposed Army bomber version of the G5N1. Four Mitsubishi Ha-111M engines. Full-scale mock-up was built in 1942, discontinued in May 1943.Famous Airplanes of the World (1984), p. 32.

Operators

; *

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 ...

Famous Airplanes of the World (1984), p. 2. **1021st ''Kōkutai''

Specifications (G5N2)

References

Notes

Bibliography

* Collier, Basil. ''Japanese Aircraft of World War II''. New York: Mayflower Books, 1979. . * *''Famous Airplanes of the World'', Bunrindō (Japan) **No. 90 ''Nakajima, Navy heavy experimental attack bomber Shinzan / Renzan'', October 1977. **No. 146 ''Nakajima Shinzan / Renzan'', November 1984. *Illustrated warplane history #5 ''Imperial Japanese Navy warplane'', Green Arrow publishing (Japan), June 1994.

External links

{{DEFAULTSORT:Nakajima G5n G05N, Nakajima G05N Abandoned military aircraft projects of Japan Four-engined tractor aircraft Mid-wing aircraft Aircraft first flown in 1941 Four-engined piston aircraft