Nakajima J1N Irving 'Gekko'

Nakajima Hikoki K. K. J1N1-S Gekkos were the first Japanese aircraft designed and built specifically to intercept and destroy other aircraft at night and in poor weather. Gekkos achieved some notable successes during three years of service with the Japanese Navy.

This design took shape in 1938 not as a night interceptor, but as a long-range fighter that could protect bombers. During the war with China, Japanese naval pilots complained of excessive bomber losses to Chinese fighters based beyond the range of Japanese fighters. The navy issued specifications to both Mitsubishi and Nakajima for a 3-seat, twin-engined escort fighter. The aircraft's speed must be at least 518 kph (322 mph) and it had to have a normal range of 2,410 km (1,496 miles) and a maximum range of 3,706 km (2,302 miles). Armament must include forward-firing cannon and machine guns plus a flexible gun to defend against tail attacks. The most important specification ultimately defeated the whole concept. The aircraft had to manoeuvre well enough to successfully engage single-engine fighters.

The Nakajima design, called the J1N1 and crafted by engineer Katsuji Nakamura, most readily met the navy's requirements and a prototype was flight-tested in May 1941. In the two years since the navy's original demand, Mitsubishi had developed and placed into service the Zero fighter and this superlative airplane had solved the bomber escort problem. Nakajima nonetheless forged ahead and flew a J1N1 prototype May 2. A year-and-a-half of flight tests proved beyond doubt that this aircraft was inferior to single-engine fighters. Except for range and takeoff distance, the type failed to meet any requirements in the 1938 specifications. The Germans also foolishly clung to the escort fighter concept. Early in the war, Germany placed in service a multi-engine, multi-seat escort fighter similar to the J1N1, the Messerschmitt Bf-110. It too failed disastrously in 1940 during the Battle of Britain when opposed by single-engine, single-seat Hurricane and Spitfire fighters. Like Nakajima, Messerschmitt salvaged this design when they transformed it into a successful night fighter.

The Japanese Navy took an interim step, however, before testing the J1N1 in night operations. The navy authorized Nakajima engineers to convert the design into a high-speed, long-range, naval reconnaissance aircraft based on land. Sweeping changes to the airframe, engines, and armament made the aircraft more reliable and suitable for the new mission. Between April 1942 and March 1943, Nakajima delivered just fifty-four of the new model, the J1N1-C, including four prototypes. U. S. forces first encountered the aircraft during early operations in the Solomon Islands and codenamed it the IRVING. The J1N1-Cs served in limited numbers and flew primarily from the great Japanese base at Rabaul on New Britain. The base was a regular target for night-flying U. S. Army Air Forces Boeing B-17 Flying Fortresses. Sometime in the spring of 1943, Commander Yasuna Kozono ordered a J1N1-C modified for night interceptor work. Maintenance crews cleaned out the observer's position behind the pilot and mounted two 20 mm cannon fixed to fire above and to the front of the new night fighter at a 30-degree angle. Two more cannons were mounted in similar fashion but fired downward. The experimental airplane was designated the J1N1-C KAI.

On the night of May 21, the modified IRVING intercepted and shot down a pair to B-17 bombers. This immediate success caught the attention of the Naval Staff and they ordered Nakajima to begin full-scale production. The new interceptor was named the J1N1-S Gekko (Moonlight). At this time, no one in Allied intelligence circles expected the Japanese to field an effective night fighter and months passed before anyone discovered what lay behind a string of regular and mysterious losses of both B-17s and Consolidated B-24 Liberator bombers. Nakajima concentrated on producing the Gekko version of the J1N for the remainder of the war.

In the summer of 1944, U. S. Marine and U. S. Army infantry divisions captured the Mariana Islands during several months of viscous combat. This important victory provided air fields from which to attack all the important Japanese cities and industrial targets in the home islands. U. S. Army Air Forces crews flying Boeing B-29 Superfortresses began flying daylight, precision bombing raids against Japan in November. In January, tactics changed to night, low-altitude attacks and the Gekko was one of many types of Japanese night fighters pressed into defending the homeland. There were some spectacular missions flown by IRVING crews but overall, Japan's night interceptors achieved limited results. The B-29 cruised approximately 80 kph (50 mph) faster than either the B-17 or B-24. Gekko crews usually could rarely make more than a single pass at the fast Superfortresses. Lt. Sachio Endo was credited with destroying eight B-29s and damaging another eight before he fell to the gun crews of a B-29. Another Gekko crew shot down five B-29s in one night but these combat successes were rare. The overwhelming number of B-29s, with their great speed and defensive firepower, were no match for Japan's night fighter forces. Escorting Allied fighter aircraft also took their toll. Many IRVINGs were shot down, destroyed on the ground, or expended during Tokko missions. Tokko is the Japanese term for Special Purpose Attackers, known in the West as kamikaze attacks. By war's end, Nakajima had built 486 Gekkos. Although the IRVING night fighter was an able night fighter, there were never enough to significantly impact the air war.