The Nakajima J1N Gekkou (Allied codename Irving) was a night fighter/reconnaissance aircraft that was used by Japan during World War II.
The first production model of the J1N1 series was the J1N1-C armored reconnaissance platform which featured two Nakajima NK1F Sakae 21 engines that were capable of propelling it at speeds of up to 529 kilometers per hour. Furthermore, the J1N had a crew of three which operated a single rear facing 13mm machine gun for defense. The total weight of the J1N1-C was around 6,800 kilograms while its total length was around 12.7 meters. The service ceiling of the J1N maxed out at around 9,300 meters with an operational range of around 1,500 kilometers.
Atlhough fundamentally unarmed and mechanically problematic, the J1N1-C still showed extreme possibility for a reliable reconnaissance platform. To solve for its mechanical issues and maneuverability issues, the designers at Nakajima removed the rear turret barbettes and removed all of the frontal weapons.
One of the very first variants of the J1N1 series was the J1N1-F which was produced with limited examples, though they did see service. This model had the main distinction of sporting a 20mm gun turret in the rear of the aircraft. In 1943 meanwhile, Japanese commander Yasuna Kozono tested an idea of placing 20mm autocannons into an upward firing position in his J1N1-C reconnaissance plane. Then, Kozono went up into combat against American war planes, downing two B-24s. Immediately, this model was put into production and became known as the J1N1-C-KAI.
Seizing the newfound data, the IJA rushed the development of the new J1N-S night fighter, which took the J1N-C frame and completely modified it. It had a modified fuselage to account for the two newly added 20mm autocannons placed in an upward firing position and two downward firing 20mm autocannons, though these were oftentimes removed in the field. This tactic, also developed by the Germans at almost the same time, was nicknamed Schräge Musik. Furthermore, the J1N-S was also equipped with either a searchlight or radar. The last two variants of the J1N1s were the J1N1-Sa which had the downward firing guns removed from the factory and the J1N1-S ko which was equipped with two 250 kilogram bombs for kamikaze missions.
The J1N1 was initially developed in 1938 as a new fighter prototype that would be able to escort the Japanese bombers from launch to return. This need came about as most of Japan's then current fighters simply did not have the range to escort said bombers the full distance. The first prototype produced to meet the specification issued by the army was the J1N1 which sported a single 20mm autocannon and two 7.7mm machine guns mounted in the nose as well as two 7.7mm barbettes in rear facing positions. However, in service trials against the A6M2 Zero, the J1N ended up being extremely unreliable, unmaneuverable, and generally disappointing. However, Nakajima worked desperately to correct these problems and eventually pushed out a far improved product in the form of the J1N1-C.
The J1N1-C first entered service with the IJA in 1942 becoming an effective reconnaissance platform. It served well in the Solomon campaign but was not performing as well as it could have been. Thus, the J1N-S was immediately put into service in early 1943. Being one of the only night fighters that Japan had produced, the "Gekkou" was well liked for its ability to easily take down heavy B-24 bombers with relative ease. However, the engine power of the aircraft did not allow for it to be able to catch up with attacking B-29 superfortresses, therefore its home island service was limited. In total, around 479 examples had been produced during the war.