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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.

When the Type "0" first flew in 1939, most Japanese pilots were enthusiastic about the new fighter. It was fast, had retractable landing gear and an enclosed cockpit, and carried two 20rnrn cannon besides the two machine guns, Initial operational evaluation in China in 1940 confirmed the aircraft's potential.

By the time of the Japanese attack on Pearl Harbor, the A6M2 was the Imperial Navy's standard carrier fighter, and rapidly replaced the older ASMs still in service. As the A6M2 proved successful in combat, it acquired its wartime nickname, "Zero," although the Japanese rarely referred to it as such. The evocative name came from the custom of designating aircraft in reference to the Japanese calendar. Thus, since 1940 corresponded to the year 2600 in Japan, the fighter was the Type "00" fighter, which was shortened to "0." The western press picked up the designation and the name "Zero" was born.

The Zero's incredible maneuverability came at some expense from its top speed. In an effort to increase the speed, the designers clipped the folding wingtips from the carrier-based A6M2 and evolved the land-based A6M3, Model 32. The pilots were not impressed with the speed increase and the production run was short, the A6M3 reverting back to its span as the Model 22. The type was originally called "Hap," after Gen Henry "Hap" Arnold, Chief of the Army Air Force. Arnold was so angry at the dubious honor that the name was quickly changed to Hamp.

The fighter received another name in 1943 which was almost as popular, especially among the American flight crews. A system of first names referred to various enemy aircraft, in much the same way that the postwar NATO system referred to Soviet and Chinese aircraft. The Zero was tagged "Zeke," and the names were used interchangeably by everyone, from flight crews to intelligence officers. (Other examples of the system included "Claude" [ASM], "Betty" [Mitsubishi G4M bomber], and "Oscar" [Ki.43].)

During the early 1940s, the skies of the Pacific were dominated by the propelled engines of the single-seat Mitsubishi Type 0 Carrier Fighters. Also known as the Zero, the Zero fighter carried Japan through several battles during World War II. The Zero's capabilities and proven power during air-to-air combat inspired awe in its enemy combatants as it was able to outmanever all other land-based aircraft of the 1940s.

In May of 1937, the Imperial Japanese Naval Air Service issued out specifications for a new updated fighter aircraft to Nakajima and Mitsubishi. IJNAS called for a fighter that could reach speeds up to 310 miles per hour at 13,120 feet and climb to 9,840 feet in 3 minutes and 30 seconds while being armed with two 20 mm cannons, two 7.7 mm machine guns and two 60-pound bombs. They also wanted it equipped with a full radio and a direction finder. With the technology available at the time, many people wondered how the specifications could be met.

Both companies began developing plans and prototypes, but when Nakajima felt the specifications were impossible to meet, they pulled their plans from the competition. Jiro Horikoshi, Mitsubishi's chief designer, believed he could create what IJNAS asked for. Horikoshi believed he could meet all IJNAS' requirements if he could find a way to make the aircraft lighter. Horikoshi found his solution. Protective armor and self-sealing fuel tanks were sacrificed to make the plane lighter and a lightweight aluminum alloy named "Extra- Super Duraluminum" was used to construct the body. Horikoshi was able to meet, and in some areas surpass, what IJNAS asked for.

Once prototypes were constructed, tested and improved on, the IJNAS began full production and delivery in December 1940. General Claire Chennault, who was working with the Chinese Nationalists to fight the Japanese in 1940, sent reports to the United States warning about the Zero's air power two years before it took to the skies. His reports were misfiled and forgotten. As a result, the U.S. Grumman F-4F Wildcats were completely shocked and overwhelmed by the Zero's superior speed and power as they tried to defend against the attacks on Pearl Harbor.

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.

The Zero remained the superior fighter in the air during the early years of World War II. It wasn't until the development of the Grumman F-6F Hellcat and the Battle of Midway that the Zero's monopoly over the Pacific Ocean skies started to decline.

Today, the shrapnel-scarred Zero Hangar across the street from the Provost Marshal's Office at Marine Corps Air Station Iwakuni remains a reminder of the presence the Zero had during the last world war. Iwakuni was home to 150 Zero fighter planes toward the end of the war. A day before the war ended, the hangar sustained damaged after a bombing. The hangar, which is the only World War II-era hangar remaining today, sits as a concrete relic, housing a replica Type Zero Carrier Fighter. The full-scale model aircraft remains housed there as a symbol of a time when the Zero once ruled the Pacific skies.




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Page last modified: 03-08-2012 18:35:22 ZULU