Nakajima J5N Tenrai (Heavenly Thunder)

History

Japanese aircraft engineers made some notable contributions to the military air force before and during World War II (1939-1945). However, like any country that evolves with technology and experience, the small Pacific nation has failed to accomplish some of its efforts. The J5N was one such forgotten design, and Project Nakajima got only six prototypes before the order was abandoned.

The twin-engine heavy fighter was developed in response to a request from the Imperial Japanese Naval Air Service (IJNAS) for a new interceptor to counter the threat of a large number of improved Allied fighter jets emerging in the Pacific Rim.

The Navy's request was made in the first half of 1943 and specified a single-seat twin-engine platform with a top speed near the 415 mark while cruising at 19,700 feet. Unlike previous Japanese naval fighters, this new aircraft should benefit from the protection afforded by armor.

The weapon needs to be powerful - a cannon battery is installed - and a bomb carrier is an added bonus.

Nakajima returned with an improved, smaller version of their J1N1 "Gekko", a three-seat platform for dedicated night fighters. Dubbed the "J5N," the new aircraft features straight-wing main aircraft, each with an engine nacelle that drives a four-bladed propeller. The cockpit is set forward along the long, tapered hull for excellent cockpit visibility. Additionally, the artillery batteries will be concentrated in the nose assembly.

The tail rests on a single vertical fin, and the landing gear uses a "trailer" arrangement.

In terms of weapons, the J5N should have either 2 x 20mm 99-2 cannons or 2 x 30mm cannons in the nose. The bomb load is listed at 551 pounds, consisting of a single-drop bomb placed under the belly.

Engines of choice are in-house Nakajima Homare 21 series 18-cylinder air-cooled radial engines, each producing up to 1,990 hp. The radials require air cooling and a larger engine nacelle, but are not as sensitive as their inline siblings.

The pilot's position in the design provides a clear view of any engine installation, while forward visibility is still reasonably good for approach and launch from the carrier deck.

Satisfied with Nakajima's offer, the Japanese Navy ordered full development of the aircraft and commissioned six prototypes to justify the design. Engineers have been battling increased weight from mandatory weapons and cockpit armor, systems and fuel storage.

The aircraft was further hampered by lower-than-expected performance from the engines due to the weight of the balloon, and in addition to that, the handling was considered unsatisfactory. An unarmed prototype took to the air for the first time on July 13, 1944, with a top speed of just 600 km/h.

This led to a period of hasty design improvements until it was realized that a complete overhaul was needed to truly meet the IJN requirements. Six planes were eventually completed - interestingly, two were completed - but four of them were ultimately lost in various accidents, proving that J5N required far more work than time allowed.

The pressure of losing the war and changing Japanese fortunes in the Pacific eventually led to the project being abandoned in February 1945. In August, Japan surrendered unconditionally, officially ending World War II.

The J5N was called "Tian Lei" when it was in service, which means "Tian Lei".

Specification

Basic

Production

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Dimensions

Weight

Performance

Performance

Armor

Changes