Kit No. 02-800
Decals: Two versions – Imperial Japanese Navy
Comments: Still available under the Hasegawa label; icludes parts for two complete aircraft; engraved panel lines; detailed radial engines; detailed cockpits include raised relief for instrument panels and flooring; ordnance includes 800 kg torpedoes or equivalent bomb load; one-piece greenhouse canopies and detailed rear machine guns; option for pre-war B5N1 or wartime B5N2 powerplants
At the outset of the war in the Pacific, the Imperial Japanese Navy had the most modern carrier-borne torpedo bomber then in operation with any of the world’s navies — the Nakajima B5N Type 97 carrier attack bomber (the Japanese term). On December 7, 1941, crewed by the elite of the Japanese Naval Air Service, 144 of these aircraft were instrumental in crippling the battleship component of the U.S. Pacific Fleet at Pearl Harbor, Hawaii — then thought to be crucial to any navy’s striking power.
The sneak attack at Pearl Harbor provided a rude shock for those who thought the Japanese backward and lacking in technical proficiency, particularly in the field of aviation. In just under three decades, Japan had transformed itself from a nation dependent on European and American aircraft designs, to one capable of independently developing cutting edge combat aircraft.
The Nakajima B5N originated with an Imperial Japanese Navy specification issued in 1935 for a modern monoplane, single-engine carrier attack bomber capable of performance on par with the IJN’s premiere shipboard fighter at the time, the Mitsubishi A5M Type 96 Carrier Fighter (later codenamed “Claude” by the Allies during the Pacific War). The IJN’s 10-Shi specification (10 signifying the tenth year of the reign of Emperor Hirohito, and “Shi” reflecting the experimental nature of the specification) required a wingspan of no more than 16 meters, with a wing folding mechanism to reduce the span to a maximum of 7.5 meters to enable the plane to fit onto the standard deck elevators of the Japanese Navy’s carriers.
Also required were a payload of one 800 kg (1764 lb.) torpedo or the equivalent bomb load, one 7.7mm machine gun, and a maximum speed of at least 207 mph at 6,560 feet. Finally, the10-Shi specification called for a crew of three, and an endurance of at least four hours at a cruising speed of 155 mph — capable of being stretched to seven hours in a pinch, most likely with auxiliary tanks. Powerplant would be a radial engine, either a Nakajima Hikari or a Mitsubishi Kinsei.
The Nakajima design team opted for a low-wing configuration fitted with a hydraulically operated retractable undercarriage. The large wing folded upwards so that the wingtips overlapped one another when folded over the cockpit. Overall length at 33 ft., 9.5 inches was sized to keep within the dimensions of shipboard deck elevators. Innovations included Fowler flaps and a variable pitch propeller.
The prototype B5N1 flew for the first time in January 1937, powered by a Nakajima Hikari air-cooled radial engine. The B5N1 went into production that November, and as 1938 dawned it went into service aboard IJN carriers as the Navy Type 97 Carrier Attack Bomber Model 11. It also began combat operations with land-based units on the Chinese mainland as a tactical bomber supporting ground operations. In this role it was successful despite its lack of armor protection for its aircrew or fuel tanks, and modest defensive armament of a single 7.7mm machine gun manned by the radio operator.
No improvements were deemed necessary during the Sino-Japanese War, but in 1939 the B5N1 underwent a re-design to prepare it to deal with more advanced fighters than those fielded by the Chinese. The result, the B5N2, first flew in December 1939. Externally identical to the B5N1, it had a more powerful engine, the 1,000 hp Nakajima Sakae 11 14-cylinder double row radial, and entered service as the Navy Type 97 Carrier Attack Bomber Model 12. The Sakae 11 had a smaller diameter than the earlier nine-cylinder Hikari 3, and so had a smaller cowling improving the pilot’s visibility and reducing drag. Providing a 36 percent increase in power over the earlier Hikari, the Sakae surprisingly did not improve the B5N’s top speed, but was more reliable and therefore embraced by the Imperial Navy, as it ensured the B5N2 could operate with greater safety for longer distances over water.
By the time of the Pearl Harbor attack, the B5N2 had completely replaced the B5N1 and its predecessor the B4Y1 in front-line IJN units. In the opening months of the Japanese conquest of the Eastern Pacific through May of 1942, the B5N2 was employed with devastating results against naval targets. In addition to the attack at Pearl Harbor, it served with distinction in every major campaign of the Imperial Japanese Navy (including the Battles of the Coral Sea, Midway, and the Solomons campaign), until it saw its last service as a torpedo bomber in the Battle of the Phillipine Sea in June 1944, after which it was replaced by the Nakajima B6N Tenzan (Allied code name: Jill).
For the remainder of the war, as it became clear that the B5N2 was easy prey for faster, more heavily armed Allied fighters, it served in maritime reconnaisance and anti-submarine roles, providing air cover for convoys and generally operating in areas of uncontested airspace. Some took part in early electronic warfare operations when fitted with air-to-surface radar, which involved installation of aerial antennae along the rear fuselage sides and wing leading edges. Still other B5N’s took on this role using Jikitanchiki magnetic airborne submarine detection devices.
Length: 33 ft. 9.5 in.
Wingspan: 50 ft. 10 15/16 in.
Powerplant: 1000 hp Nakajima NK 1B Sakae 11 14-cylinder air-cooled radial engine
Maximum speed: 235 mph at 11,810 ft.
Rate of Climb: 9, 845 ft in 7 mins. 40 sec.
Service Ceiling: 27,100 ft.
Range: 528 nautical miles (normal); 1,075 nautical miles (maximum)
Armament: One flexible rearward firing 7.7mm machine gun, one 800kg (1,764 lb.) torpedo, or identical weight in bombs
Mania’s B5N Kate is injection molded in grey and consists of 66 parts for each aircraft, including the single-piece greenhouse canopy, four assorted operating lights, and the window for the wing center section to assist in aiming the torpedo or bombs. The cockpit is fairly well detailed, featuring seats, control stick, bulkheads, and raised detail on the instrument panel and cockpit floor. The radial engines are also well-detailed and may tempt some modelers to depict the plane undergoing maintenance. There is an option to build the kit as either the pre-Pearl Harbor B5N1with a single row radial Nakajima Hikari engine, or the B5N2 double row radial engine (the upgraded Nakajima Sakae powerplant) employed from Pearl Harbor onwards — with different cowlings for each.
Given the level of cockpit detail, it is a shame that the canopy is a single piece, as combined with the cockpit’s other virtues, there is a small amount of interior sidewall detail on the starboard side in the form of instrument panels, one of which looks like it could be a radio. The seats are basic and could stand to be dressed up by seat straps, but there is no reason to undertake the effort unless you are willing to open up the canopy. The airframe features crisp engraved panel lines and raised detail on the ailerons and rudder. The landing gear and armament are pretty basic; while the rear machine gun looks detailed enough to pass a cursory inspection, the torpedo bears raised panel lines and the bombs look roughly accurate but do not especially stand out.
The kit decals look pretty old and are probably best replaced by aftermarket examples. The instructions are entirely in Japanese, and include color plates providing illustrations for four different aircraft in three different paint schemes (two of them are Nakajima Green over Grey), but there is no way to tell what units they represent.
Overall this a great kit, notable to for its engraved panel lines and fairly detailed cockpit, more than enough to keep most modelers interested in Imperial Japanese Navy aircraft of WWII happy. These features were more than sufficient at the time of the kit’s release to give Hasegawa a run for its money (some of the molds for these Mania kits were likely purchased by Hasegawa). All with the bonus of outstanding color plates.
- Japanese Aircraft of the Pacific War by R.J. Francillon; Copyright 1970 Putnam & Company Limited, London