Warplanes of Japan: Nakajima J5N1 Tenrai

Nakajima J5N1 Tenrai

(USAAF Photo)

The J5N1 was designed in 1943 as a single-seat twin-engine interceptor fighter. It was was developed as an interceptor for countering attacks by Boeing B-29 Superfortress.capable of reaching 414 mph. It had a pair of 1990 hp Nakajima Homare 21 radial engines and was armed with two 20mm cannons and two 30mm cannons. During flight trials in 1944 the prototype only reached 371 mph. Six prototypes were built, but the type was not put into production.  (The J5N1 was not assigned an Allied reporting name).

The layout of the J5N was similar to the J1N: a low set wing on which were mounted the two powerplants, 1,484 kW (1,990 hp) Nakajima Homare 21 18-cylinder air-cooled radial engines, with a long fuselage ending in a conventional tail arrangement. For maximum utilization of the power from the twin engines, large four-blade propellers were fitted which also featured large spinners (as fitted to the J1N). The main wheels retracted rearwards into the engine nacelles, and the tailwheel was fixed. The cockpit was set above the wing, and featured a starboard-opening canopy. The nose was streamlined to offer the pilot an excellent forward view during landing, takeoff and taxiing.

Armament of the J5N consisted of two 30 mm and two 20 mm cannon, and provision was made for a centreline 250 kg (550 lb) bomb. The J5N was designed to combat the large, heavily armed and fast B-29 Superfortress, and so required such heavy armament in order to do severe damage in the brief windows of time allowed for firing passes. To concentrate the firepower, the four cannons were mounted in the nose of the J5N; if a single-engine fighter were unfortunate enough to find itself in front of a J5N, a single hit from a 30mm shell would have been more than adequate to destroy it.

Impressed with the design, the JNAF authorized the development of the J5N1, assigned the name Tenrai (天雷, "Heavenly Thunder"), and six prototypes were requested to be built. Progress was impeded by the failure of the engines to produce their promised power, and by a steady increase in the weight of the airframe as the need to reverse the long-standing policy of giving low priority to armor protection led to a buildup of weight and a drop in performance. The first prototype – lacking its armament – made its first flight 13 July 1944, and was something of a disappointment. The top speed attained was only 597 km/h (371 mph) – far below the specified 666 km/h (414 mph) of the requirement. Despite the other five prototypes also having flown with numerous enhancements, the aircraft never achieved its design speed, and the project was abandoned soon after in February 1945. Four of the six experimental aircraft were lost to accidents. Two prototypes were shipped to the USA..The rear fuselage, fin, a left wing panel and fuel cells of a J5N1 are in storage at the National Air and Space Museum. (Wikipedia)

(USAAF Photos)

Nakajima J5N Tenrai

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