Nakajima J5N

During the spring of 1943, the JNAF issued an 18-Shi specification for a single-seat twin-engine interceptor capable of reaching a top speed of 666 km/h (414 mph) at 6,000 m (19,690 ft). Nakajima submitted a proposal based on the earlier J1N1 Gekko three-seat night fighter, although this new aircraft – designated J5N1 – was slightly smaller. 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 {{nihongo||天雷|Tenrai|"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.Berliner 2011, p. 149. The first prototype – lacking its armament – made its first flight July 13, 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.Shigeru 2000, p. 56.

• J5N1 : Single-seat interceptor fighter aircraft. Six built.

The rear fuselage, fin, a left wing panel and fuel cells of a J5N1 are in storage at the National Air and Space Museum.{{cite web |title=Nakajima J5N1 Tenrai (Heavenly Thunder) |url=http://airandspace.si.edu/collection-objects/nakajima-j5n1-tenrai-heavenly-thunder/nasm_A19731574000 |website=National Air and Space Museum |publisher=Smithsonian Institution |access-date=13 February 2024}}

{{Aircraft specs

|ref=Francillon 1970, p. 492.

|prime units?=met

|crew=1 (two aircraft completed as two-seaters)

|length m=11.46

|span m=14.4

|height m=2.38

|gross weight kg=7,300

|eng1 number=2

|eng1 name=Nakajima Homare 21

|eng1 type=18-cyl. air-cooled radial piston engines

|eng1 hp=1,990

|perfhide=

|max speed kts=322

|max speed note=achieved

::::({{convert|666.7|km/h|kn|abbr=on|0}} at {{convert|6,000|m|ft|abbr=on|0}} specification)

|climb rate ms=15

|wing loading kg/m2=230

|power/mass=0.40 kW/kg (0.24 hp/lb)

|guns=

• 2 × 30 mm Type 5 cannon

::::and/or

:* 2 × 20 mm Type 99-2 cannon

|bombs= 1 × 250 kg (551 lb) bomb

}}

{{aircontent|

|related=

|similar aircraft=

• de Havilland Hornet
• Grumman F7F Tigercat
• Kawasaki Ki-96
• Mitsubishi Ki-83

|lists=

|see also=

}}

{{Reflist}}

{{Refbegin}}

• Berliner, Don. Surviving Fighter Aircraft of World War Two: Fighters. London: Pen & Sword Aviation, 2011. {{ISBN|978-1-8488-4265-6}}.
• Francillon, Rene J. Japanese Aircraft of the Pacific War (1st ed.). London: Putnam & Company Ltd., 1970. {{ISBN|0-370-00033-1}}.
• Green, William. Warplanes of the Second World War, Volume Three: Fighters. London: Macdonald & Co.(Publishers) Ltd., 1961. {{ISBN|978-0-356-01447-0}}.
• Nohara, Shigeru.Photo Book Japanese Fighter(in Japanese). Kojinsha, 2000. {{ISBN|978-4-7698-1493-1}}.
• Townend, David R. Thunderbolt & Lightning. Markham: AeroFile Publications, 2008, {{ISBN|978-0-9732020-2-1}}.

{{Refend}}

{{commons category|Nakajima J5N Tenrai}}

{{Nakajima aircraft}}

{{Japanese Navy short aircraft designations}}

{{Imperial Japanese Navy official aircraft names}}

J05N, Nakajima

J05N

Category:Abandoned military aircraft projects of Japan

Category:Mid-wing aircraft

Category:Aircraft first flown in 1944

Category:Twin piston-engined tractor aircraft

Category:Aircraft with retractable conventional landing gear