|G5N2 Shinzan Kai|
|Manufacturer||Nakajima Aircraft Company|
|First flight||8 April 1941|
|Primary user||IJN Air Service|
2 of G5N1
4 of G5N2
|Developed from||Douglas DC-4E|
The Nakajima G5N Shinzan (深山"Mountain Recess") was a four-engined long-range heavy bomber designed and built for the Imperial Japanese Navy prior to World War II. 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 3,000 nmi (5,600 km; 3,500 mi). 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 airliner. 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 for dismantling and inspection.
The design that emerged from this study was for an all-metal mid-wing monoplane with fabric-covered control surfaces and powered by four 1,870 hp Nakajima NK7A Mamori 11 air-cooled radial engines driving four-bladed propellers. Notable features included a long ventral bomb-bay, glazed nose and twin tailfins replacing the DC-4E's distinctive triple rudder. The DC-4E's retractable tricycle undercarriage was retained, as well as the original wing form and powerplant arrangement. Defensive armament comprised one 20mm Type 99 Model 1 cannon each in a power-operated dorsal and tail turret plus single-mount hand-operated 7.7mm Type 97 machine guns 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.
Of the six completed Shinzans, four of them 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.
- G5N1 Experimental Type 13 Land-based Attack Bomber "Shinzan" (13試陸上攻撃機 深山 13-Shi Rikujō Kōgekiki "Shinzan")
- Prototype, two built. Initial named Experimental Type 13 Large-size land-based Attack Bomber (13試大型陸上攻撃機 13-Shi Ōgata Rikujō Kōgekiki). Four-engined heavy bomber/torpedo bomber. Three-blade propeller, mounted four Mitsubishi MK4B Kasei 12 (1,530 hp) radial engines.
- G5N2 Test production "Shinzan Kai" (試製深山改 Shisei "Shinzan Kai")
- Supplementary prototype, four built. Four-blade propeller, mounted four Nakajima NK7A Mmaori 11 (1,870 hp) radial engines. All G5N2s were rebuilt to G5N2-L in 1943.
- G5N2-L "Shinzan Kai" Freighter (深山改輸送機 "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.
- Crew: 7 (G5N1/2), 6 (G5N2-L)
- Length: 31.02 m (101 ft 9 in)
- Wingspan: 42.12 m (138 ft 2 in)
- Height: 8.8 m (27 ft 6 in)
- Wing area: 201.8 m² (2,171.37 ft²)
- Empty weight: 20,100 kg (44,300 lb)
- Loaded weight: 28,150 kg (62,060 lb)
- Max. takeoff weight: 32,000 kg (70,528 lb)
- Powerplant: 4 × Nakajima NK7A "Mamori-11" 14-cylinder air-cooled radial Sumitomo/Hamilton four-blade constant-speed, 1395 kW (1870 hp) each
- Maximum speed: 420 km/h (227 kn, 261 mph)
- Cruise speed: 278 km/h (150 kn, 173 mph, G5N1)
- Range: 4,260 km (2,302 nmi, 2,648 mi)
- Service ceiling: 7,450 m (24,442 ft)
- 2,000-4,000 kg (4,408-8,816 lb) bombs or torpedoes
- 2× 1,500 kg torpedoes
- 2× 1,500 kg bombs
- 4× 800 kg bombs
- 12× 250 kg bombs
- 24× 60 kg bombs
- 4,000 kg freight (G5N2-L)
- Related development
- Aircraft of comparable role, configuration and era
- Collier, Basil. Japanese Aircraft of World War II. New York: Mayflower Books, 1979. ISBN 0-8317-5137-1.
- Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd., 2nd edition 1979. ISBN 0-370-30251-6.
- 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. ISBN 978-4-76633-161-5
Media related to Nakajima G5N Shinzan at Wikimedia Commons