Modern-Aviation

The Mitsubishi J2M Raiden was a single-engined land-based fighter aircraft used by the Imperial Japanese Navy Air Service in World War II. The Allied reporting name was "Jack". The J2M was designed by Jiro Horikoshi, creator of the A6M Zero, to meet the 14-Shi official specification. It was to be a strictly local-defense interceptor, intended to counter the threat of high-altitude bomber raids, and thus relied on speed, climb performance, and armament at the expense of manoeuvrability. The J2M was a sleek, but stubby craft with its oversized Mitsubishi Kasei engine buried behind a long cowling, cooled by an intake fan and connected to the propeller with an extension shaft.

The J2M Raiden (translating to "Thunderbolt" and codenamed "Jack" by the Allies) was primarily used as a local defense fighter / interceptor by the Imperial Japanese Navy (IJN). The aircraft was developed to combat the growing threat of high-flying American bombers - primarily the new Boeing B-29 "Superfortresses" being used during daylight raids over Japan. The J2M's design was attributed to Jiro Horikoshi, famous engineer of the fabled A6M "Zero" IJN fighter aircraft that provided near-complete air dominance for the Empire during the early years of the war. Introduced in December of 1942, the Raiden fought on well into 1945 (the final year of World War 2) where it was eventually retired from service in August with the fall of the Japanese Empire itself.

Design of the J2M was traditional, with the cockpit seated in the middle of the stubby fuselage, a single vertical fin at rear and the powerplant up hled up front. Wings were rounded monoplanes and low-mounted just forward and under the cockpit seating area, which had accommodations for a single pilot. The engine was of a Mitsubishi design, an MK4R-A Kasei 23a 14-cylinder 2-row radial piston engine, developing 1,800 horsepower.

As an interceptor, the J2M design centered around a powerful armament array. This consisted of 4 x 20mm Type 99-2 cannons in the wings. Fuel drop tanks could added for increased range at the expense of weight and performance. By all accounts, the Raiden offered up poor visibility for the pilot but made up for it in performance, firepower and rate of climb - factors vital in the success of any interceptor of the time. Production of the Raiden totaled some 621 aircraft and covered six variants from J2M1 through J2M6.

Initially, the service models of the J2M were plagued by engine issues that limited the reach of the aircraft, delaying outright production by up to a year or more. Some J2M's fought on in the Battle of Philippine Sea but were mostly relegated to homeland defense as the war progressed. Their use became increasingly light as the Americans would adapt to nighttime bombing raids, effectively rendering further development of the J2M's a moot point.

Series Model Variants
• J2M1 - Prototype Model Designation; fitted with Mitsubishi MK4C Kasei 13 14-cylinder air-cooled radial piston engine of 1,400 horsepower; 2 x 7.7mm Type 97 machine guns in fuselage and 2 x 20mm Type 99 Model II cannons in wings.
• J2M1 Model 11 - Similar to J2M1; fitted with Mitsubishi MK4R-A Kasei 23a 14-cylinder radial piston engine of 1,820 horsepower.
• J2M3 Model 21 - Fitted with Mitsubishi MK4R-A Kasei 23a engine; 2 x 20mm Type 99 Model II cannons in wings and 2 x 20mm Type 99 Model I cannons in wings.
• J2M3a Model 21A - Fitted with Mitsubishi MK4R-A Kasei 23a engine; 4 x 20mm Type 99 Model II cannons in wings.
• J2M4 Model 32 - Prototype Model; fitted with Mitsubishi MK4R-C Kasei 23c engine of 1,820 horsepower; 2 x 20mm Type 99 Model I cannons at oblique angle in fuselage and 2 x 20mm Type 99 Model 2 cannons in wings.
• J2M5 Model 33 - Fitted with turbocharged Mitsubishi MK4U-A Kasei26a series engine of 1,820 horsepower; short range; improved performance model; 2 x 20mm Type 99 cannons in fuselage and 2 x Type 99 Model II cannons in wings.
• J2M5a Model 33a - 4 x 20mm Type 99 Model II cannons in wings.
• J2M6 Model 31 - Based on the J2M3 model; redesigned cockpit and canopy.
• J2M6a Model 31A - Based on the J2M3a model; redesigned cockpit and canopy; single example produced.
• J2M7 Model 23A - Proposed Model based on the J2M3; fitted with Kasei 26a series engine.
• J2M7a Model 23A - Proposed Model based on the J2M3a; fitted with Kasei 26a series engine.

After the decisive Battle of Midway in 1942 Japan's military leaders rushed to re-equip their forces for defense of the home islands. In fighter designs the interceptor role now took priority over forward projection of offensive power. Allied forces, meanwhile, sought to establish air superiority over Japanese-held territories via B-29 bombing raids on industrial targets.

The struggle to meet production demands sparked a Japanese initiative to recruit shonenko (child labour) from Taiwan (Formosa). Though the target of 25,000 youths was never reached, over 8,400 Taiwanese youths aged 12 to 14 relocated to Mitsubishi plants to help build the J2M Raiden.
The Allied advance took its toll. In 1945 aircraft production in Japan collapsed, as numbers for the J2M reflect.

Performance
Maximum speed: 596km/h （370 mph, 322kt） (@5450m)
Range: 1467 km (912 nmi, 795 mi)
Service ceiling: 11,430 m (37,500 ft)
Rate of climb: 1402 m/min (4,600 ft/min)
Wing loading: 174 kg/m² (35 lb/ft²)
Power/mass: 0.42 kW/kg (0.26 hp/lb)

Armament
2x Type 99-2 inboard wing-mounted 20x101mmRB cannon with 190 rpg
2x Type 99-1 outboard wing-mounted 20x72mmRB cannon with 210 rpg
2× 60 kg (132 lb) bombs or 2 × 200 L (53 US gal) drop tanks or single larger central drop tank