The Mitsubishi A6M Zero
By Chuck Hawks
It is hard for modern researchers to understand just how dominant the Zero was in the early years of the Pacific War. No Allied plane could stand against it. The obsolete Brewster Buffalo and the sleek looking but comparatively low performance Bell P-39 fared poorly against the Zero. The best of the early American Army fighters was probably the Curtis P-40, and the early models of this fighter were distinctly inferior in most respects to the Zero. Even the contemporary models of the famous British Spitfire and Hurricane fighters, which had won the Battle of Britain, had major problems with the Zero when they met in 1942.
At sea, the situation was hardly much better. The U.S. Navy's Grumman F4F Wildcat was out classed by the Zero, although it probably provided the best competition of any of the Allied fighter in the theater. Navy and Marine pilots used the stubby fighter's maneuverability to good advantage in the desperate early battles in the Pacific.
Most of Japan's many top aces flew the Zero. Prominent among them is Saburo Sakai (with 64 victories), the top scoring Japanese ace to survive the war, and Hiroyoshi Nishizawa (actual total of victories unknown, but 104 confirmed), perhaps the greatest Japanese ace of them all. Among other Japanese aces, Shoichi Sugita had 120+ victories, Tadashi Nakajima 75+, Naoishi Kanno 53, Teimei Akamatsu 50+, and Kinsuke Muto 35.
Not only could the Zero out fight any Allied fighter, it also out-ranged them. Many people do not realize that the Zero was the world's first long range escort fighter. Zeros flew long range bomber escort missions during the war in China, before the Pacific war even began, and throughout WW II Japanese carrier air groups out-ranged their US counterparts, primarily because of the great range of the Zero fighter. If the Germans had the long range Zero instead of the short range ME 109, the outcome of the Battle of Britain might have been very different. As famous as the Zero was, it is probably still under rated by most people.
The Zero was designed by Jiro Horikoshi (my father, who had a hand in the P-38 and later models of the P-51 as an AAF aeronautical engineer, was honored to meet Mr. Horikoshi after the war) to fulfill Japanese Navy requirements for great range, rapid climb, high speed, and above all superior maneuverability. These were the characteristics desired by Japanese fighter pilots. In order to get them, the Zero was designed with a very low wing loading; pilot armor and self sealing fuel tanks were dispensed with. Japanese fighter pilots, who generally chose not to wear parachutes in combat (even when ordered to do so), gladly gave up such safety features in order to achieve a fighter with superior agility.
For those of you who do not understand this wing loading thing, let me make a comparison between a couple of birds that almost everyone is familiar with. Doves fly fast, and are very acrobatic birds. They have a low wing loading. Ducks fly fast, and can dive like a stone, but they are not very acrobatic. Ducks have a high wing loading. The former have a lot of wing lift for their body weight; the latter have a lot of body weight compared to their wing lift.
The Zero's performance fell off at high altitudes, but the American fighters that opposed it early in the war were even worse in that regard. At low and medium altitudes, nothing could touch the Zero.
The first production version of the Zero was the A6M2 Model 11, of 1940. This had a Nakajima Sakae 12 engine, a 14-cylinder air cooled radial that developed 950 hp. at 13,800 ft. The similar Model 21 had folding wing tips for aircraft carrier use. This was the model on board the Japanese carriers at the beginning of the Pacific War on December 7, 1941. It was also the model captured almost undamaged in the Aleutians in 1942, and examined in detail by American engineers.
The A6M2 had a top speed of 316 m.p.h. at 16,400 ft., and a range of 1,265 miles on internal fuel. With an under fuselage drop tank, the range was extended to 1,930 miles. The standard Zero armament was 2-7.7mm machine guns in the engine cowling, and 2-20mm cannon in the wings. Wingspan was 39 ft. 5 in.
The next main version of the Zero was the A6M3, which appeared late in 1942. This version was powered by an up-rated 1,130 hp. Sakae 21 radial engine, with a two stage supercharger that improved high altitude performance. Top speed was increased to 336 m.p.h. at 19,865 ft. Best climb rate was 4,500 ft./min. Armament and range remained about the same.
By this time, the American AAF had P-38F/G Lightnings to augment the improved P-40E/F models facing the Japanese fighters, whose margin of superiority was diminishing. The Allied fighters used their superior speed and dive rate to "hit and run," a tactic that negated the Zero's superior climb and turning ability. The rule for Allied pilots was "never turn with a Zero." Instead, they would roll and dive away.
The A6M3 Model 32 had clipped wing tips, achieved by removing the folding wing tips of the carrier model. This was intended to improve the roll rate, which was inferior to that of American fighters. This model also had reduced internal fuel capacity (down to 134 gallons from the 156 gallon capacity of the A6M3 Model 22). The Zero was beginning to show its age.
The reduced wing span (36 ft. 2 in.) of the Model 32 was carried over to the next model. The A6M5 Model 52 of 1943-1944 probably represents the design peak of the Zero fighter. In response to the continually improving performance of the latest Allied fighters, this model had the improved Sakai 31 engine with ejector exhaust stacks to augment thrust, the reduced wing span of the Model 32 (but with the familiar rounded shape of earlier Zeros), plus heavier wing skin. On most airplanes, the 7.7mm wing MG were replaced by 12.7 mm MG. The accumulated increased weight, plus the loss of wing area, increased the wing loading, slightly decreasing maneuverability. Speed was now up to 358 m.p.h., and dive limit speed to 410 m.p.h. Best climb rate was 3,340 ft./min.
The specifications which follow are for the A6M5 Model 52 of 1943.
The A6M5a had an improved wing cannon and carried more ammunition. The dive limiting speed was raised to 460 m.p.h. These models still lacked any protection for the pilot, self sealing gas tanks, or even an emergency release for the canopy.
The A6M5b of 1944 finally addressed some of these problems. It had an armored glass windshield, automatic fire extinguishers for the fuel tanks. Armament was two 12.7mm MG and two 20mm cannon. By this time the performance of the Zero had, in most respects, fallen well below that of its contemporary major adversaries, the P-38J Lightning, the F6F Hellcat, and the F4U Corsair. It remained, however, a very dangerous opponent in a "turn and burn" dogfight.
The final version of the Zero was the A6M8c of 1945, which just reached production as the war ended. A new 1,560 hp. Kinsei 62 radial engine provided a top speed of 355 m.p.h. at 19,680 ft, and an improved climb rate, but it was too little too late.
By then, the Zero had fallen hopelessly behind, and more modern Japanese fighters were at last in production. These included the Raiden interceptor (also designed by Jiro Horikoshi), and the Shinden high altitude fighter, an outstanding airplane that might have given the American fighters a lot of trouble if a sufficient quantity could have been produced.
The Zero was a landmark fighter when it was introduced, perhaps the best in the world. But (like the Hurricane and the P-40) it lacked the development potential of some of its contemporaries, such as the British Spitfire and German ME 109. And the Japanese were slow to implement needed improvements. The A6M5b of 1944, for example, incorporated improvements that most U.S. fighters had received in 1942. The Zero's period of superiority could have been extended had the Japanese been able to implement improvements more rapidly.
Japan also lacked the industrial potential to produce aircraft of all types, and particularly fighters, in sufficient quantity. A total of 10,936 Zero fighters of all types were produced. That is a lot of airplanes, but pales in comparison with the (approximately) 13,700 P-40's, 12,200 Hellcats, 12,500 Corsairs, 15,300 P-47's, 14,000 Hurricanes and Sea Hurricanes, 10,000 P-38's, 22,800 Spitfires and Seafires, and 15,000 P-51's that constituted its main opponents. Great numbers of those Allied fighters were sent to the European Theater, of course, but it is worth noting that Japanese fighter pilots were forced to fight from a position of numerical inferiority for most of the war.
Even given its technical and numerical inferiority, in the hands of an accomplished pilot the Zero remained a formidable adversary right to the end of the war. For example, the Japanese ace Saburo Sakai blundered alone into a formation of 15 Hellcats during the defense of Iwo Jima. By that time Sakai was debilitated by war wounds and blind in one eye, but in a very long running dogfight fight the Hellcat pilots could not nail his agile Zero fighter. In fact, after he finally made it home, completely exhausted, his astonished ground crew inspected his plane and discovered that not a single enemy bullet had hit the ace's Zero!
In his book Samurai Saburo Sakai tells the story of another incredible air battle. In February 1945 the ace Kinsuke Muto, alone in his Zero, attacked 12 Corsair fighters. In the course of the wild dogfight that ensued, Muto shot down 4 Corsairs before running out of ammunition and escaping. Such battles, like the Zero fighter itself, are the stuff of legend.
Copyright 2003 by Chuck Hawks. All rights reserved.