Nakajima B6N Tenzan (Jill)

History

The torpedo bomber was born in the pre-World War I era (1914-1918) and changed significantly by World War II (1939-1945) - although the basic attack concept remained the same. This type is a special platform with a structure designed for severe surface flight and strong enough to carry and deliver heavy torpedo payloads against enemy surface ships.

By then, the old biplanes had given way to all-metal monoplane designs, although some of the latter were still in service at the outbreak of World War II (like some entries for the Royal Navy). The torpedo bomber enables war planners to launch a coordinated air attack on enemy ships from an aircraft carrieran extension of torpedo attacks that previously relied on warships equipped with torpedo tubes or submarines lurking underwater for short periods of time.

Japan's Nakajima Aircraft Company has been supplying naval aircraft (A1N) since 1927 and produced many designs before and during the Great War. In 1937, the prototype that would become the B5N torpedo dive bomber (Allied codename "Kate") flew for the first time. It entered service some time later and 1,149 of these monoplanes were produced.

The B6N "Tian Shan" ("Tian Shan") originated before the war and was developed by the Nakajima Company. Its first flight took place in March 1941, but due to a longer development time, it was not put into service until August 1943.

There were approximately 1,268 An example of this design was subsequently given the Allied code name "Gill". The aircraft had a limited lifespan due to the transfer of air superiority to the Allies during the 1945 war.

The B6N is designed to support the operational limitations identified by the earlier B5N series - namely performance and range. This led the Imperial Japanese Navy (IJN) to develop a new specification of a carrier-based attack platform with a state-of-the-art design capable of carrying a wartime payload of up to 1,800 pounds to 1,200 miles per hour at a cruising speed of 230 mph. Top speed approaches 300 mph. A new Nakajima series "Mamori 11" 14-cylinder air-cooled radial engine will power the design, which will include three operators including a pilot, a radio operator/gunner and a bombardier (who also acts as a navigator) )flight). meeting.

It was originally expected to use a Mitsubishi "Kasei" engine - but Nakajima engineers successfully sold the rights to their in-house development.

This has resulted in a largely conventional design for the aircraft - a slender fuselage is required for the desired performance and portability. A single engine attached to the nose will power the airframe. The three crew members will sit in a row under a long-running thick glass canopy (greenhouse-style) that provides excellent visibility around the aircraft. A defensive position was added to the rear of the canopy section with a 7.7mm Type 92 machine gun mounted on a trainable mount. The torpedo load will remain below the centerline of the hull.

The wing main aircraft is mounted low and placed slightly forward amidships. The tail is conventional, with a single vertical tail and a low-mounted horizontal plane. The landing gear adopts a "trail" arrangement, and the main legs can be stowed under the wings. Size matched to Japan Airlines' hangar lifts at the time, Fowler flaps were used to slow the aircraft's attack speed and landing maneuvers on the carrier deck.

The Nakajima engine drives a four-bladed propeller unit.

The prototype took off on March 14, 1941, although it didn't happen overnight - the powerful engines produced more torque than expected, causing the plane to constantly want to roll. This resulted in changes to the vertical stabilizer, but the new engine still had problems, with overheating and excessive vibration found during test flights. Modifications were made, but also delayed, and the aircraft was formally tested on the deck of a Japanese carrier in 1942.

At the end of the evaluation phase, the engine proved operational and an abdominal 7.7mm machine gun position was added to protect the vulnerable bottom of the aircraft from trailing interceptors. This position is reached through a tunnel and the machine gun is retractable to maintain aerodynamics when not in use.

In the first half of 1943, the design was commissioned for serial production as the "B6N1". The aircraft would carry a torpedo into combat, which was standard at the time, and surprisingly, self-sealing fuel tanks were not part of the final design - increasing the operational range but making the aircraft very vulnerable to the type of enemy fire. With production increasing and over 100 completed, it was decided to swap these dynamic engines for the originally envisioned 1,850 hp Mitsubishi Kasei 25 series. This resulted in a slight lengthening of the nose section to accommodate changes in the natural center of gravity (CoG) of the engine and airframe.

These changes subsequently led to the new designation "B6N2" (Model 12).

Then every third B6N2 was equipped with surface search radar equipment, enabling the flying group to find and mark its own targets. With a total of 1,131 units produced, the B6N2 became the definitive model in the series.

The B6N2a (Type 12A) is equipped with improved defensive armament, replacing the 7.7mm Type 92 system with a larger caliber 13mm Type 2 heavy variant for increased firepower.

The B6N2 has a total length of 10.8 meters, a wingspan of 15 meters and a height of 3.8 meters. It has a curb weight of 6,635 pounds and a maximum takeoff weight (MTOW) of 12,450 pounds. The Kasei 25 radial engine (1,850 hp at takeoff) has a top speed of 300 mph and a cruising speed of up to 205 mph.

Range is a useful 1,900 miles with a service cap of 29,650 feet. Its war load consisted of a 1,760-pound torpedo, or the equivalent of a conventionally dropped bomb.

As the war situation in Japan was deteriorating every month, and its aircraft carrier attack power was more or less offset by the Allied offensive, it was thought to create a land-based version of this aircraft, resulting in the "B6N3" ( 13)) specified. These will carry a 1,850-horsepower Mitsubishi MK4T-C "Kasei 25c" engine and modified land-based landing gear.

For this variant, however, the war ended too quickly and only two prototypes were completed.

Specification

Basic

Production

Roles

Dimensions

Weight

Performance

Performance

Armor

Changes