Mitsubishi A6M Zero

The Mitsubishi A6M Zero was a long-range fighter aircraft, manufactured by Mitsubishi Heavy Industries, and operated by the Imperial Japanese Navy from 1940 to 1945. The A6M was designated as the Mitsubishi Navy Type 0 Carrier Fighter, or the Mitsubishi A6M Rei-sen. The A6M was usually referred to by its pilots as the "Reisen" (zero fighter), "0" being the last digit of the Imperial year 2600 (1940) when it entered service with the Imperial Navy. The official Allied reporting name was "Zeke", although the use of the name "Zero" was later commonly adopted by the Allies as well.

When it was introduced early in World War II, the Zero was considered the most capable carrier-based fighter in the world, combining excellent maneuverability and very long range. In early combat operations, the Zero gained a legendary reputation as a dogfighter, achieving the outstanding kill ratio of 12 to 1, but by mid-1942 a combination of new tactics and the introduction of better equipment enabled the Allied pilots to engage the Zero on generally equal terms.

The Imperial Japanese Navy Air Service ("IJNAS") also frequently used the type as a land-based fighter. By 1943, inherent design weaknesses and the failure to develop more powerful aircraft engines meant that the Zero became less effective against newer enemy fighters, which possessed greater firepower, armor, and speed, and approached the Zero's maneuverability. Although the Mitsubishi A6M was outdated by 1944, design delays and production difficulties of newer Japanese aircraft types meant that it continued to serve in a front line role until the end of the war. During the final years of the War in the Pacific, the Zero was also adapted for use in kamikaze operations. During the course of the war, Japan produced more Zeros than any other model of combat aircraft.


Mitsubishi A6M Zero
Class Aircraft
Type Fighter
Manufacturer Mitsubishi Aircraft Corporation
Production Period 1940 - 1945
Origin Japan
Country Name Origin Year
Japan 1939
Country Name Operational Year Retirement Year
China View
Indonesia View
Japan 1940 1945 View
Thailand (Siam) View
ManufacturerName Production From Production To Quantity
Mitsubishi Aircraft Corporation 1940 1945 10939 View

The Mitsubishi A5M fighter was just entering service in early 1937, when the Imperial Japanese Navy started looking for its eventual replacement. In May, they issued specification 12-Shi for a new carrier-based fighter, sending it to Nakajima and Mitsubishi. Both firms started preliminary design work while they awaited more definitive requirements to be handed over in a few months.

Based on the experiences of the A5M in China, the Imperial Japanese Navy sent out updated requirements in October calling for a speed of 600 km/h (370 mph) and a climb to 3,000 m (9,800 ft) in 3.5 min. With drop tanks, they wanted an endurance of two hours at normal power, or six to eight hours at economical cruising speed. Armament was to consist of two 20 mm cannons, two 7.7 mm (.303 in) machine guns and two 30 kg (66 lb) or 60 kg (132 lb) bombs. A complete radio set was to be mounted in all aircraft, along with a radio direction finder for long-range navigation. The maneuverability was to be at least equal to that of the A5M, while the wingspan had to be less than 12 m (39 ft) to allow for use on an aircraft carrier. All this was to be achieved with available engines, a significant design limitation. The Zero's powerplant seldom reached 750 kilowatts (about 1,000 hp) in any of its variants.

Nakajima's team considered the new requirements unachievable and pulled out of the competition in January. Mitsubishi's chief designer, Jiro Horikoshi, thought that the requirements could be met, but only if the aircraft could be made as light as possible. Every possible weight-saving measure was incorporated into the design. Most of the aircraft was built of a new top-secret 7075 aluminium alloy developed by Sumitomo Metal Industries in 1936. Called Extra Super Duralumin (ESD), it was lighter and stronger than other alloys (e.g. 24S alloy) used at the time, but was more brittle and prone to corrosion[6] which was countered with an anti-corrosion coating applied after fabrication. No armor was provided for the pilot, engine or other critical points of the aircraft, and self-sealing fuel tanks, which were becoming common at the time, were not used. This made the Zero lighter, more maneuverable, and the longest range single engine fighter of WWII; which made it capable of searching out an enemy hundreds of kilometres (miles) away, bringing them to battle, then returning hundreds of kilometres back to its base or aircraft carrier. However, that trade in weight and construction also made it prone to catching fire and exploding when struck by enemy rounds.

With its low-wing cantilever monoplane layout, retractable, wide-set landing gear and enclosed cockpit, the Zero was one of the most modern aircraft in the world at the time of its introduction. It had a fairly high-lift, low-speed wing with a very low wing loading. This, combined with its light weight, resulted in a very low stalling speed of well below 60 kn (110 km/h; 69 mph). This was the main reason for its phenomenal maneuverability, allowing it to out-turn any Allied fighter of the time. Early models were fitted with servo tabs on the ailerons after pilots complained control forces became too heavy at speeds above 300 kilometres per hour (190 mph). They were discontinued on later models after it was found that the lightened control forces were causing pilots to overstress the wings during vigorous maneuvers.

It has been claimed that the Zero's design showed clear influence from American fighter planes and components exported to Japan in the 1930s, and in particular the Vought V-143 fighter. Chance Vought had sold the prototype for this aircraft and its plans to Japan in 1937. Eugene Wilson, President of Vought, claimed that when shown a captured Zero in 1943, he found that "There on the floor was the Vought V 142 [sic] or just the spitting image of it, Japanese-made," while the "power-plant installation was distinctly Chance Vought, the wheel stowage into the wing roots came from Northrop, and the Japanese designers had even copied the Navy inspection stamp from Pratt & Whitney type parts." While the sale of the V-143 was fully legal, Wilson later acknowledged the conflicts of interest that can arise whenever military technology is exported. Counterclaims maintain that there was no significant relationship between the V-143 (which was an unsuccessful design that had been rejected by the U.S. Army Air Corps and several export customers) and the Zero, with only a superficial similarity in layout. Allegations about the Zero being a copy have been mostly discredited.

The first Zeros (pre-series A6M2) went into operation in July 1940. On 13 September 1940, the Zeros scored their first air-to-air victories when 13 A6M2s led by Lieutenant Saburo Shindo attacked 27 Soviet-built Polikarpov I-15s and I-16s of the Chinese Nationalist Air Force, shooting down all the fighters without loss to themselves. By the time they were redeployed a year later, the Zeros had shot down 99 Chinese aircraft (266 according to other sources).

At the time of the attack on Pearl Harbor 420 Zeros were active in the Pacific. The carrier-borne Model 21 was the type encountered by the Americans. Its tremendous range of over 2,600 km (1,600 mi) allowed it to range farther from its carrier than expected, appearing over distant battlefronts and giving Allied commanders the impression that there were several times as many Zeros as actually existed.

The Zero quickly gained a fearsome reputation. Thanks to a combination of excellent maneuverability and firepower, it easily disposed of the motley collection of Allied aircraft sent against it in the Pacific in 1941. It proved a difficult opponent even for the Supermarine Spitfire. Although not as fast as the British fighter, the Mitsubishi fighter could out-turn the Spitfire with ease, could sustain a climb at a very steep angle, and could stay in the air for three times as long.

Soon, however, Allied pilots developed tactics to cope with the Zero. Due to its extreme agility, engaging a Zero in a traditional, turning dogfight was likely to be fatal. It was better to roar down from above in a high-speed pass, fire a quick burst, then climb quickly back up to altitude. (A short burst of fire from heavy machine guns or cannon was often enough to bring down the fragile Zero.) Such "boom-and-zoom" tactics were used successfully in the China Burma India Theater (CBI) by the "Flying Tigers" of the American Volunteer Group (AVG) against similarly maneuverable Japanese Army aircraft such as the Nakajima Ki-27 Nate and Nakajima Ki-43 Oscar. AVG pilots were trained under their commander Claire Chennault's instructions to exploit the advantages of their P-40s, which were very sturdy, heavily armed, generally faster in a dive and level flight at low altitude, with a good rate of roll.

Another important maneuver was Lieutenant Commander John S. "Jimmy" Thach's "Thach Weave", in which two fighters would fly about 60 m (200 ft) apart. If a Zero latched onto the tail of one of the fighters, the two aircraft would turn toward each other. If the Zero followed his original target through the turn, he would come into a position to be fired on by the target's wingman. This tactic was first used to good effect during the Battle of Midway, and later over the Solomon Islands. Many highly experienced Japanese aviators were lost in combat, resulting in a progressive decline in the quality of the opponents faced by Allied pilots, which became a significant factor in Allied successes. Unexpected heavy losses of these pilots at the battles of the Coral Sea and Midway dealt the Japanese carrier air force a blow from which it never fully recovered.

Role Fighter
Manufacturer Mitsubishi Heavy Industries, Ltd
Designer Jiro Horikoshi
(chief designer)
First flight 1 April 1939
Introduction 1 July 1940
Retired 1945 (Japan)
Primary users Imperial Japanese Navy Air Service
Chinese Nationalist Air Force
Produced 1940–1945
Number built 10939
Variants Nakajima A6M2-N


General characteristics

  • Crew: one
  • Length: 9.06 m (29 ft 9 in)
  • Wingspan: 12.0 m (39 ft 4 in)
  • Height: 3.05 m (10 ft 0 in)
  • Wing area: 22.44 m² (241.5 ft²)
  • Empty weight: 1,680 kg (3,704 lb)
  • Loaded weight: 2,410 kg (5,313 lb)
  • Powerplant: 1 × Nakajima Sakae 12 radial engine, 709 kW (950 hp)
  • Aspect ratio: 6.4

Performance

  • Never exceed speed: 660 km/h (356 kn, 410 mph)
  • Maximum speed: 533 km/h (287 kn, 331 mph) at 4,550 m (14,930 ft)
  • Range: 3,105 km (1,675 nmi, 1,929 mi)
  • Service ceiling: 10,000 m (33,000 ft)
  • Rate of climb: 15.7 m/s (3,100 ft/min)
  • Wing loading: 107.4 kg/m² (22.0 lb/ft²)
  • Power/mass: 294 W/kg (0.18 hp/lb)

Armament

  • Guns
    2× 7.7 mm (0.303 in) Type 97 aircraft machine guns in the engine cowling, with 500 rounds per gun.
    2× 20 mm Type 99-1 cannon in the wings, with 60 rounds per gun.
  • Bombs:
    2× 60 kg (132 lb) bombs or
    1× fixed 250 kg (551 lb) bomb for kamikaze attacks

End notes