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G8N *Renzan*
G8N Renzan
General information
Type	Heavy bomber
National origin	Japan
Manufacturer	Nakajima Aircraft Company
Status	retired
Primary user	Imperial Japanese Navy Air Service
Number built	4
History
Introduction date	1945
First flight	23 October 1944
Retired	August 1945

The Nakajima G8N Renzan (連山, "Mountain Range") was a four-engined long-range bomber designed for use by the Imperial Japanese Navy. The Navy designation was "Type 18 land-based attack aircraft" (十八試陸上攻撃機); the Allied code name was "Rita".

Design and development

In February 1943 the Imperial Navy staff asked Nakajima Aircraft Company to design a four-engined bomber, capable of meeting an earlier specification set for a long-range land-based attack plane. The final specification, issued on 14 September 1943, called for a plane with a maximum speed of 320 knots (590 km/h; 370 mph) able to carry a 4,000 kg (8,800 lb) bomb-load 2,000 nmi (3,700 km; 2,300 mi) or a reduced bomb-load 4,000 nmi (7,400 km; 4,600 mi).^[1]

Nakajima's design featured a mid-mounted wing of small area and high aspect ratio, a tricycle landing gear and a large single-fin rudder. Power came from four 2,000 hp Nakajima NK9K-L "Homare" 24 radial engines with Hitachi 92 turbosuperchargers driving four-bladed propellers. The engines were cooled by counter-rotating fans positioned just inside the engine cowlings.^[1] Defensive armament included power-operated nose, dorsal, ventral and tail turrets along with two free-swiveling machine guns at the beam positions.^[2]

Operational history

The initial prototype was completed in October 1944 and delivered to the Navy for testing in January 1945, a year after the Navy ordered development to start. Three further examples were completed by June 1945, with the third prototype being destroyed on the ground by US carrier aircraft.^[2]

Other than minor problems with the turbosuperchargers, the Renzan performed satisfactorily and the Navy hoped to have a total of 16 prototypes and 48 production-version G8N1s assembled by September 1945. But the worsening war situation and a critical shortage of light aluminium alloys led to the project's cancellation in June.^[2]

One proposed variant was the G8N2 Renzan-Kai Model 22, powered by four 2,200 hp Mitsubishi MK9A radial engines and modified to accept attachment of the air-launched Ohka Type 33 Special Attack Bomber.^[2]

Just before Japan's surrender in August 1945 consideration was also briefly given to producing an all-steel version of the aircraft, to be designated G8N3 Renzan-Kai Model 23, but the cessation of hostilities precluded any further development.^[2]

After the war, one prototype was taken to the United States^[3]^[4] and scrapped after testing. None are in existence today.

Variants

G8N1 : Four-engine heavy bomber. Production version.
G8N2 : Modified to carry Ohka Type 33 Special Attack Bomber. Four Mitsubishi MK9A radial engines.
G8N3 : All-steel airframe.

Operators

Japan

Imperial Japanese Navy Air Service
- Naval Air Technical Arsenal (and after february 1945, reorganised to 1st Naval Technical Arsenal)

Specifications (G8N1)

Data from Japanese Aircraft of the Pacific War^[2]

General characteristics

Crew: 10
Length: 22.935 m (75 ft 3 in)
Wingspan: 32.54 m (106 ft 9 in)
Height: 7.2 m (23 ft 7 in)
Wing area: 112 m² (1,210 sq ft)
Airfoil: root: K251; tip: K159^[5]
Empty weight: 17,400 kg (38,360 lb)
Gross weight: 26,800 kg (59,084 lb)
Max takeoff weight: 32,150 kg (70,879 lb)
Powerplant: 4 × Nakajima NK9K-L Homare 24 18-cylinder air-cooled radial piston engines, 1,500 kW (2,000 hp) each for take-off

1,380 kW (1,850 hp) at 8,000 m (26,000 ft)

Propellers: 4-bladed constant-speed metal propellers

Performance

Maximum speed: 593 km/h (368 mph, 320 kn) at 8,000 m (26,000 ft)
Cruise speed: 370 km/h (230 mph, 200 kn) at 4,000 m (13,000 ft)
Range: 3,945 km (2,451 mi, 2,130 nmi)
Ferry range: 7,464 km (4,638 mi, 4,030 nmi)
Service ceiling: 10,200 m (33,500 ft)
Time to altitude: 8,000 m (26,000 ft) in 17 minutes 34 seconds
Wing loading: 239.3 kg/m² (49.0 lb/sq ft)
Power/mass: 0.2191 kW/kg (0.1333 hp/lb)

Armament

Guns:
- 6× 20 mm Type 99 cannon - 2 each in the dorsal, ventral, and tail turrets
- 2× 13 mm (.51 in) Type 2 machine guns in nose turret
- 2× 13 mm (.51 in) Type 2 machine gun in fuselage sides
Bombs:
- 2x 2,000 kg (4,409 lb) bombs - maximum
- 4x 250 kg (551 lb) bombs - normal

References

Notes

^ ^a ^b Francillon 1979, p. 440.
^ ^a ^b ^c ^d ^e ^f Francillon 1979, p. 441.
^ Thorpe 1977, p. 27.
^ A G8N "Rita" in the USA via http://www.ww2incolor.com
^ Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography

Collier, Basil. Japanese Aircraft of World War II. New York: Mayflower Books, 1979. ISBN 0-8317-5137-1.
Francillon, René J. (1979). Japanese Aircraft of the Pacific War (2nd ed.). London: Putnam & Company Ltd. ISBN 0-370-30251-6.
Thorpe, Donald W. (1977). Japanese Naval Air Force Camouflage and Markings World War II. Fallbrook, California: Aero Publishers, Inc. ISBN 0-8168-6583-3.
Unknown authors. Famous Airplanes of the World: Nakajima Shinzan / Renzan (Volume 11, no.146). Japan: Bunrin-Do, Nov. 1984.