J1N “Irving”, Japanese Fighter

Photograph of J1N "Irving" fighter

U.S. Navy. From Francillon (1979)

Nakajima J1N1-S Gekko ("Moonlight") “Irving”


Crew 2
Dimensions 55’8” by 40’0” by 15’0”
16.98m by 12.77m by 4.562m
Wing area 431 square feet
40 square meters
Weights 10.697-18,043 lbs
4840-8184 kg
Maximum speed       315 mph at 15,000 feet
583 km/h at 5840 meters
Cruising speed 160 mph at 12,000 feet
257 km/h at 3700 meters
Climb rate 33 feet per second
10.1 meters per second
Service ceiling 30,610 feet
9320 meters
Power plant Two 1130 hp (843 kW) Nakajima NK1F Sakae (one Sakae 21 and one Sakae 22) fourteen-cylinder air-cooled radial engines driving opposite rotating three-blade constant-speed metal propellers.
Armament Two fuselage-mounted upward-firing 20 mm Type 99 cannon
Two 20 mm Type 99 downward-firing cannon
External stores
2 330 liter (72.6 gallon) drop tanks
2 551 lb (250kg) bombs (as kamikaze)
Range 1585 miles (2550 km) normal
2330 miles (3750 km) overloaded
Fuel capacity
374 gallons
1700 liters
Production A total of 479 J1Ns were built by Nakajima Hikoki K.K. at Koizumi as follows:
  2 J1N1 prototypes (spring 1941)
  7 J1N1-C prototypes (1941-42)
  54  J1N1-C and J1N1-R (1942-7 to 1943-3)
  183 J1N1-C KAI and J1N1-S (1943-4 to 1944-3)
  233 J1N1-S and J1N1-Sa (1944-4 to 1944-12)

The –C was a reconnaissance aircraft with a crew of 3 and armed with one rear-firing flexible 13 mm Type 2 machine gun. It was later redesignated the -R.

The -C KAI were -Cs converted to night fighters. They otherwise resembled the -S.

The -Sa carried armament of two fuselage-mounted upward-firing 20 mm Type 99 cannon and either was fitted with airborne radar or a forward-firing 20mm Type 99 cannon.

Airborne radar was also retrofitted to some -S units.

"Irving" was originally designed as a long-range escort fighter, based on a 1938 specification for a fighter capable of escorting Japanese bombers on raids against airfields deep in Chinese territory.  The design was inspired by the French Potez 63, with heavy armament and the maneuverability to engage single-seat fighters. The design team, led by Nakamura Katsuji, chose to power the aircraft with matched handed engines to elimnate engine torque, and armed the prototype with both forward-firing cannon and machine guns and a pair of remote-controlled dorsal barbettes. The first prototype flew in May 1941 but had serious bugs, and a second prototype was equipped with both trailing flaps and leading edge slots. Both prototypes were heavy and had excessively complex hydraulic systems. Though very maneuverable for a two-engine fighter, it could not match the A6M "Zero" in any performance category but range.

As a result, the Navy ordered the airframes already on the assembly line to be completed as reconnaissance aircraft with the dorsal barbettes removed, the fuel capacity reduced, and the engines replaced with unhanded Sakae 21s. Provisions for drop tanks were made to restore some of the range. The reconnaissance design was designated as the J1N1-C (and later redesignated as the J1N1-R.)

An imaginative commander found in the spring of 1943 that "Irving" could be rearmed with oblique cannon as a night fighter, and most of the production was converted to night fighters on this plan under the designation J1N1-C KAI. Additional aircraft built from scratch as night fighters were designated as the J1N1-S. Unfortunately for the Japanese, this robust night fighter lacked the speed to make more than a single pass at the fast, high-flying B-29s, though it proved effective against patrolling B-24s.

Most of the surviving "Irvings" were expended as kamikazes in 1945.


Francillon (1979)

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