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Further Reading

Mitsubishi A6M Zero / Zeke

The Allies' main opponent in the Pacific air war, the Zero is the most famous symbol of Japanese air power during World War II. The fighter first flew in April 1939, and Mitsubishi, Nakajima, Hitachi and the Japanese navy produced 10,815 Zeros from 1940-1945. Zeros were produced in greater number than any other aircraft. Its distinctive design and historical impact make the Zero an important machine in air power history. The Mitsubishi A6M Zero was the linchpin of early Japanese strategic success. Without the Zero's range and effectiveness in air-to-air combat, the Pearl Harbor attack and the conquest of the Philippines and Netherlands East Indies would have been problematic at best.

The Zero got its name from its official designation, Navy Type Zero Carrier-Based Fighter (or Reisen), though the Allies code-named it "Zeke." The Zero was the successor to the A5M Type 96 "Claude." Mitsubishi designed the A6M from Navy requirements set out in 1937 for a fighter that was fast, maneuverable and had great range.

The Zero was the first carrier-based fighter capable of besting its land-based equivalents. This is remarkable in light of the fact that the design of carrier-based aircraft is inherently more difficult than that of the land-based equivalents. Not only do arrested carrier landings call for a considerably stronger, and hence heavier, structure; final approach speeds must be low by land-based standards and handling characteristics must be exceptionally good if high operational losses are to be avoided.

The Zero was an improbably good design, and one for which there was no available substitute. This combat aircraft was designed to a tight and seemingly impossible specification calling for unprecedented range and maneuverability in a carrier fighter. The Zero had a maximum speed of 334 mph and a range of 1,130 miles. Designed as a carrier-borne fighter, it was exceptionally light compared to its opponents. This requirement was not only necessary to provide maneuverability but also was caused by the Zero's low-powered engine.

The Mitsubishi A6M Zero is the rare example of a first-rate combat aircraft powered by a mediocre engine. Indeed, Japanese engineers consciously compensated for the fact that Japanese aero engines were, quoting the Zero's designer Horikoshi Hiro, "20 to 30 percent less powerful than those of the more advanced countries." Lack of interservice cooperation in engine development limited the horsepower available to Japanese designers.

The Zero's range, an essential precondition to early Japanese victories in the Pacific, was the compromise of an extremely light, yet strong, structure and the provision of a jettisonable centerline external fuel tank. The Zero's remarkable maneuverability in air-to-air combat combined a low wing loading and excellent power-to-weight ratio with a potent armament of two wing-mounted 20 mm cannon plus two 7.7 mm machine guns in the engine cowling, mainly to help the pilot aim the cannon. In order to obtain the remarkable wing loading and power-to-weight ratio that made the Zero formidable, designer Horikoshi dispensed with protective armor and self-sealing fuel tanks and Zero pilots wore no parachutes. This was not, as is commonly imputed, because the Japanese Navy placed a low value on the lives of its pilots or because of a "kamikaze mentality," but due to a rational assessment of pilot survival factors. Unlike its main allied opponents, the Zero, with flotation bags in the wings, had excellent ditching characteristics.

On the negative side of the strategic ledger, the Zero's remarkable performance was gained at the expense of vulnerability to battle damage. Other consequences included omitting armor protection for the pilot, not using self-sealing fuel tanks, and building lightweight wings as an integral part of the fuselage. Its tactical effectiveness was thus heavily dependent upon pilot skill, magnifying the strategic impact of the loss of the Japanese Navy's cadre of experienced aviators in the Solomons campaign.

The Zero's critical dependence upon pilot skill was its Achilles heel. Once the Japanese Navy had expended its cadre of skilled aviators in the Solomons campaign, the Zero's prime liability, extreme vulnerability to battle damage, made it a death trap.

The A6M first saw combat in China in the late summer of 1940, and it quickly helped Japan dominate the air in Asia. When Japan attacked Pearl Harbor on Dec. 7, 1941, 125 Zeros from six aircraft carriers participated. In the early part of the war, Allied aircraft such as the Curtiss P-40 and Seversky P-35 were at a disadvantage in a dogfight with a Zero flown by a skilled pilot, and the A6M became a well-known and dangerous opponent.

The Japanese advantage, however, began to disappear as American tactics evolved. American pilots gained experience fighting the Zero in China with the American Volunteer Group, known as the Flying Tigers, and at the Battle of Midway. The key to fighting the Zero was to stay out of dogfights, and instead use superior armament and hit-and-run diving attacks against the relatively fragile A6M. American fighters introduced in 1943 were more powerful (2,000-hp engines), faster, and had much more firepower than the Zero. As Allied pilots used their heavily-armed aircraft to advantage, the Zero's dominance ended. At the same time, the number of American aircraft and pilots increased, and the number of experienced Japanese aircrew shrank.

Initially, the principal fighter models flown by the USAAF were various series of the Curtiss P-40 and Bell P-39, while the USN and USMC generally flew various series of the Grumman F4F. In general, each of these early American fighters were somewhat deficient in tactical performance compared to the Zero. The deficiencies were not decisive but did put the Americans at some overall tactical disadvantage, all else equal (which it seldom was in actual combat). In addition, the Zero had a significant advantage in operating radius. The overall effect of this was to limit the American fighters largely to defensive counterair (DCA) operations, while allowing the Japanese more scope for offensive counterair (OCA).

In Jun 1942 USAAF forces in the Pacific began to receive small numbers of Lockheed P-38 fighters.56 By Sep 1942 there were 105, representing ten percent of USAAF fighter forces in theater. By mid 1943 USAAF forces in the Pacific had begun to receive Republic P-47 and North American P-51 fighters as well. By Jun 1943 these three more modern models accounted for twenty percent of USAAF fighters arrayed against Japan, while by Dec the proportion had risen almost to fi fty percent.58 Similarly, by the early months of 1943 Vought F4U fighters were beginning to replace Grumman F4Fs in land-based action, while the new aircraft carriers reaching the Pacific from mid 1943 onward were all equipped with Grumman F6Fs.

These newer fighters held margins of tactical performance over the Zero that were broadly comparable to those that the Zero held over the earlier US fighters. That is to say that all else equal, the pilot in one of these aircraft would have a small margin of tactical advantage. It is easy to overstate the significance of these margins, however. For the most part the speed margins were no greater than ten percent, for instance. Differences in tactical circumstances, and in particular in pilot skill, could easily be far more significant. Perceptions of the significance of the newer aircraft are probably considerably exaggerated by the concurrent changes in the balance of pilot skills, owing largely to the established disparities in operational as well as combat loss rates together with differences in pilot production and in the efforts made to preserve pilots.

By the middle of the war, both the Mitsubishi and Nakajima design teams had abandoned the overly simple design approach in favor of a more Western-style design; the Nakajima Frank and Mitsubishi Jack of the late war period are altogether much more powerful and capable aircraft. While development of the Zero continued by adding self-sealing tanks, armor plate and increasing horsepower to 1,150 hp, the later Zero was much heavier and thus less nimble. Weight increased 28 percent, but horsepower increased only 16 percent, degrading overall combat performance.

Beginning around October 1944 during the battle for the Philippines, Zeros were used in kamikaze attacks. Kamikazes used A6Ms more than any other aircraft for these suicide missions. Japanese Air Forces, no longer able to match the American planes and fliers, started using suicide (kamikaze) attacks. Japanese pilots on a kamikaze mission would deliberately crash their explosive-packed planes into enemy targets, most frequently ships. Kamikaze attacks accounted for 50 percent of the damage to American vessels during the entire war. The Mitsubishi Zero was the primary kamikaze plane, but almost every type of aircraft was used. Obsolete planes and any aircraft that could be fixed long enough to make a one- way flight were adapted for suicide missions. Also, new aircraft were produced specifically as kamikaze instruments.