The Mitsubishi A6M "Rei-sen" was the primary naval fighter of the Japanese Empire heading into World War 2. The aircraft was recognized by its pilots as the "Zero-sen" based on the Imperial Year calendar (1940 at the time). The Allies eventually adopted the "Zero" name as the type's nickname while the official Allied codename for the became "Zeke". The A6M received much attention in the early stages of the war in the Pacific where it became the first naval aircraft to be able to best any of its land-based counterparts through a combination of speed, maneuverability and range. Mitsubishi Heavy Industries of Japan produced some 10,939 examples from 1940 on. The series survived the whole of the war up to the Japanese surrender of September 1945, its worth having been proven over five years of conflict.
Origins of the A6M lay in pre-war 1937 by which time Mitsubishi had just delivered the A5M. The A5M was a monoplane fighter developed for the Imperial Japanese Navy and incorporated a streamlined fuselage, low, forward-set monoplane wings and a single-seat cockpit. While 1,094 of the type were taken into inventory, the type still held some old-fashioned design elements which rendered it an obsolete-appearing aircraft by World War 2 standards. It held an open-air cockpit for the pilot with a raised fuselage spine and fixed, spatted main landing gear legs. Visibility out of the cockpit was poor and armament centered on a pair of 7.7mm Type 89 series machine guns.
With these limitations in mine, the Imperial Japanese Navy pushed both Mitsubishi and Nakajima for a new carrier-borne naval fighter of greater capability - particularly range to prove important over the vast spans of Pacific Ocean in the upcoming Japanese campaign. Also, the hitting power of the aircraft was to be improved by implementation of cannon armament coupled to machine guns for a formidable one-two punch. Due to the space on Japanese carriers, the aircraft would also have to be relatively compact and feature folding wing assemblies for storage. The IJN sought particular specifications out of their new mount: a maximum speed of 310 miles per hour and a climb rate of 9,850 feet reached in 3.5 minutes.
Nakajima engineers eventually found the requirements too restrictive and did not submit a formal design, leaving Mitsubishi to head the project. Their design (attributed to Jiro Horikoshi) became a smoothly contoured monoplane wing fighter with a fully-enclosed cockpit and wholly retractable landing gear legs. The engine was fitted to a compartment at the front of the fuselage in the usual way and the wings sat ahead of midships. Visibility was slightly improved over that as found on the A5M as the fuselage spine was lowered into the fuselage shape. The canopy was of greenhouse style and still provided for adequate situational awareness for the pilot. The wingtips could fold upwards for a reduced wingspan in storage. One of the qualities of the Mitsubishi design that would prove both good and bad was its lack of armoring for the major components of the aircraft - cockpit, engine and fuel tanks (as well as self-sealing fuel tanks). While the lack of this armor protection made for a lighter, and therefore more agile, aircraft, it decidedly reduced the survivability of both crewman and airframe in a fight against equal or superior fighters. The Mitsubishi design was also an excellent turning machine, which gave it an edge against contemporaries for a time. Armament was a mix offering of 2 x 20mm cannons in the wings and 2 x 7.7mm machine guns in the engine cowling. Power was from a Nakajima radial piston engine driving a three-bladed propeller.
The initial prototype was unveiled on March 16th, 1939 and achieved first flight on April 1st of that year. On September 14th, the aircraft was officially adopted by the IJN as its new standardized carrier-based fighter mount. Initial aircraft were powered by a Mitsubishi engine (Zuisei line) until a decided shift was made towards a Nakajima product. The Mitsubishi aircraft was adopted as the A6M "Zero-sen" Type 00 Fighter and saw its first service in July of 1940 against the Chinese. It quickly proved itself the finest fighter in the world and bested nearly all opponents in the Asian and Pacific theaters and certainly alerted observers in Washington, D.C. and elsewhere but nothing was done to further investigate the type.
Production of A6Ms eventually eclipsed all other Japanese aircraft of the war. Mitsubishi was its maker but additional manufacture was handled through competitor Nakajima who produced over 6,200 examples alone. Additional production was seen from Hitachi and Sasebo and included a floatplane derivative which also saw extensive service in the war.
By the time of the Japanese surprise attack on Pearl Harbor, Hawaii, on December 7th, 1941, the IJN managed a stable of some 400 Zero fighters and the carrier groups to field them. Zeros took part in the devastating attacks which rendered many USN warships useless or damaged and thrust the United States into a formal war declaration against the Empire of Japan. From there on, the A6M was fielded in all major Japanese campaigns and retained its air dominance heading into 1942 and 2 x 132lb bombs were added for the ground strike role. The aircraft now deserved the respect of Washington observers and its capabilities were fully noticed.
It was not until the middle of 1942 that the Allies managed to capture an intact A6M and study it from the inside out back in the United States. It was from this work that the weaknesses of the Mitsubishi aircraft were soon discovered and new counter tactics arranged for Allied pilots. The lack of armoring proved a critical design flaw in the Zero and Allied pilots would work at exploiting this fatal flaw. Additionally, the United States Navy was now turning to more modern, capable fighting mounts in their F6F Hellcats and F4U Corsairs replacing outgoing frontline types like the F4F Wildcats. The turning point in the early stages of the Pacific war then came at the Battle of Midway in June of 1942 where these new American fighters squared off against incoming waves of Zeros and earned a tremendous victory in the process. The Americans benefitted from armoring of critical components, improved weaponry and tactics and increased performance from dominant engines. Against this, the Zero had now met its official match.
From 1943 onwards, the Zero proved a far lesser, more vulnerable foe than seen in the early stages of the war. A "definitive" Zero was produced as the A6M8 which incorporated a Nakajima Kinsei engine of 1,560 horsepower but the arrival of this variant proved a moot addition. Tide had shifted away from the Japanese Empire and for the Allies and territorial losses mounted into 1945. The Zero was eventually relegated as a carrier for suicidal airmen in the kamikaze strikes that followed. These were outfitted with 1 x 550lb bombs for maximum carnage.
Operators beyond the Imperial Japanese Navy were few and included Thailand. Post-war use was seen by China (Republic of China) and Indonesia. Several airframes exist in flyable form today and many have survived as museum showpieces. Some have had screen time in several motion pictures to date.
(OPERATORS list includes past, present, and future operators when applicable)
✓Air-to-Air Combat, Fighter
General ability to actively engage other aircraft of similar form and function, typically through guns, missiles, and/or aerial rockets.
✓Maritime / Navy
Land-based or shipborne capability for operating over-water in various maritime-related roles while supported by allied naval surface elements.
SYNCHRONIZED / INTERRUPTOR GEAR
Automatic weapons are synchronized to fire through the spinning propeller blades via special mechanical gear arrangement.
Mainplanes are designed to fold, improving storage on land and at sea.
Can accelerate to higher speeds than average aircraft of its time.
Can reach and operate at higher altitudes than average aircraft of its time.
EXTENDED RANGE PERFORMANCE
Capability to travel considerable distances through onboard fuel stores.
Design covers the three all-important performance categories of speed, altitude, and range.
Ability to operate over ocean in addition to surviving the special rigors of the maritime environment.
Manual process of allowing its pilot and / or crew to exit in the event of an airborne emergency.
Features partially- or wholly-enclosed crew workspaces.
Features retracting / retractable undercarriage to preserve aerodynamic efficiency.
29.7 ft (9.06 m)
36.1 ft (11.00 m)
9.8 ft (2.98 m)
4,136 lb (1,876 kg)
6,025 lb (2,733 kg)
+1,889 lb (+857 kg)
(Showcased structural values pertain to the Mitsubishi A6M5 Rei-sen (Zero) production variant)
1 x Nakajima NK1C Sakae 21 14-cylinder, two-row, air-cooled radial piston engine developing 1,130 horsepower driving 1 x Three-bladed propeller unit in puller/tractor arrangement.
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