Chapter 3

Trial and Error

In the official designation in Japan of the A6M, the letter A designated it was a carrier fighter, the letter M indicated it was a Mitsubishi design, and the figure 6 meant it was the sixth such type designed by that company. A second figure was added after this indicating the production series. Thus the A6M1 was the prototype indicator. The designation Type ‘O’ was an abbreviation of the Japanese year in which it appeared, which in the case of the A6M was the Japanese Year 2600. It was not until 31 July 1940 that the official designation The Type Zero Carrier-Based Fighter, Model 11 was formally adopted and Mitsubishi was notified of this fact. This was quickly modified into everyday usage as the ‘Type 00’, which in turn became simplified to ‘Zero’ around the world, although other Japanese aircraft had been accepted in this same year. Each version of the aircraft was also allocated a Model Serial, the first being Model 11 and this aircraft, sixty-six of which were initially produced, had fixed elliptical wing-tips. An adaption to enable the A6M to fit the new carrier’s lifts and hangars was the adoption of folding wing-tips and this became the Model 21, arguably the most famous Model of many that subsequently followed. The Japanese also referred to this aircraft as the Rei-sen, which was a composite word amalgamating rei (Zero) with the abbreviation of the Japanese for fighter, Sentoki, which became shortened to sen. Common usage both at home and abroad settled, after various alternatives such as Navy-O, Double-OO and so on, to Zero. Another option was Reisen Kanjukisen (Celebration) marking the 2,600th anniversary of Emperor Jimmu’s reign. When later allocated a name under the Allied code system devised in July 1942 by Captain Frank T. McCoy’s Air Technical Intelligence Unit (ATIU) at Hangar 7, Eagle Farm airfield, Brisbane, the A6M was designated as the ‘Zeke’.¹ Other units referred to them as the ‘Ben’ and others as the ‘Ray’ for short periods. Later a variant, the Zeke 32, received the separate name of Hap, later changed to Hamp for a while due, it was rumoured, to the strong and indignant objections of General Henry H. ‘Hap’ Arnold, Chief of the USAAF, himself; while a floatplane fighter variant received the code-name Rufe. But whether the Reisen, Zeke or Navy-O, she was to achieve world-wide immortality as the Zero.

Many foreign observers at the time (indeed many current American diehards), amazed at the performance of the A6M fighter, totally refused to accept that this aircraft was the result of Japanese thinking and originality. Even today some websites contain such claims; even the Grumman F6F Hellcat is touted as a contender on one forum even though it appeared five or six years later than the A6M and was specifically designed to counter it! Aside from such nonsense however, serious allegations have been made down the years.

Even decades after end of the war Americans doggedly maintain that Horikoshi copied features from American aircraft of the period, even vastly inferior ones! Their mind-set remain firmly fixed in an outdated and never very accurate cultural assessment, which even Japan’s post-war technical dominance failed to expunge. Examples abound but we can look at a few.

Over four decades on from the war’s termination Air Force journalist Gary Boyd repeated a twenty-year-old claim originally made by another author in a British magazine² that Horikoshi merely copied the best features of the Vought V-143 fighter. This prototype had been rejected by the United States Army Air Service (USAAS)³ but the Mitsubishi Company bought it and shipped it back to Japan for detailed analysis around the same time that Horikoshi was beginning his design work for the A6M.⁴ The allegation has more recently been regurgitated yet again.⁵

Originally a 1935 Northrop concept, the 3A, this single-seater, low-wing, monoplane fighter with enclosed cockpit and retractable undercarriage, was developed from the XFT carrier prototype, which Vought took over in 1936, when she became re-designated as the V-141. The USAAC rejected her in favour of the Seversky P-35. Re-modified as the V-143 with a 750hp (551.62kW) Pratt & Whitney R-1535-A5G radial engine, she was again rejected, this time by Argentina, Turkey, Norway, Sweden and Yugoslavia. The re-engined aircraft was otherwise modified but once more rejected by the USAAC in June 1937. The aircraft was demonstrated to a certain

Captain (later Rear-Admiral) Misao Wada of the engineering division of the IJN at Hartford, Connecticut, on 26 April by well-known Test Pilot Edmund T. Allen. They asked whether it could be fitted with the Swedish Oerlikon FF (under licences as the ‘Aerlikan’ Type ‘E’ or Type 99-1) 20mm wing cannon (oddly, the current IJN terminology of the day termed these weapons machine-guns). The fixed wing-mounted cannon were supplied from 60-round drum magazines firing 72RB rounds at 490rpm, with a muzzle velocity of 1,970ft/sec (600m/sec).⁶ The weight of each projectile was 129 grams and the weight of each gun was 50.7lb (23kg).⁷ These new weapons were to be produced by a new arms manufacturer established by a group of retired admirals, the Dai Nihon Heiki KK.

In July 1937 the aircraft was finally sold to Mitsubishi for $175,000 and they duly tested as Navy Experimental Fighter Type AXVI for the IJN, and they, in turn, rejected it as being inferior to current Navy type fighters! And that was that. However, in 1946 an American newspaper columnist, one Drew Pearson, ran a story on the sale and how, during an inspection of an A6M shot down over Honolulu during the Pearl Harbor assault, Vought’s President, Eugene E. Wilson, had told Admiral Chester W. Nimitz, Commander-in-Chief, Pacific Fleet, ‘… that’s a Vought-Northrop fighter I tried to sell the Navy …’. Further fuel to the fire came from Vought’s Chief Engineer Fred N. Dickerman, who stated, ‘… the Zero was just a copy of an airplane that Northrop originally designed and built’. In fact, the only thing comparable between the two designs appears to have been the landing gear retraction system.

Another much-touted American contender for the Zero’s origin has been the Hughes 1B Racer – a product of the febrile and erratic genius of Howard Hughes. Designed for Hughes by Richard Palmer, the H-1 was indeed a groundbreaker, a cantilever monoplane incorporating many revolutionary construction techniques, such as flush riveting to leave a smooth aluminium skin with no drag and similarly both the main undercarriage and the tail skid were fully retractable to aid the same result.⁸ As a low-wing monoplane in the age of biplanes the H-1 found no favour with the USAAC, being too much ahead of its time. Despite its powerful 700hp (522kW) Pratt & Whitney R-1535 two-row 14-cylinder radial being tuned to emit more than 1,000hp (750kW), thus giving her a maximum speed of 352mph (566km/h) when she broke the world landplane speed record in 1935, no military orders resulted. With new wings the H-1 also smashed the non-stop transcontinental speed record in 1937.

Hughes himself kick-started this myth post-war when he stated that Mitsubishi filched large parts of his design, claiming that it was obvious to everybody that on examination of the two aircraft the Japanese Zero fighter was substantially a copy of the Hughes H-1 Racer. Hughes, who was actually defending himself from hostile press accusations of actually designing the Zero for the Japanese, said:

The Japanese Zero was a shock of the utmost magnitude to the United States because it had been thought up to that time that the Japanese were far inferior mechanically. I should say in point of aircraft design and mechanical aptitude, to the United States and nobody expected the Japanese to have an airplane that would be at all competitive. Well, in any event, when one of these Japanese Zeroes was finally captured and studied and analyzed it was quite apparent to everyone that it had been copied from the Hughes plane …

A certain Al Ludwick had stated that Japanese generals had made a detailed inspection of the H-1 in New Jersey pre-war, at least according to Bill Utley, who acted as the Hughes Corporations publicity officer. This unsubstantiated story (the Japanese Army Air Force had no input whatsoever into Japanese Navy aviation), was given wide publicity and is still repeated, but in an exclusive interview with one aviation writer, Horikoshi himself totally denied that the H-1 had any influence on his design.⁹ He stated later that with regard to the A6M nothing came directly from any foreign design. Fortunately, the National Air & Space Museum houses both the H-1, donated to the Smithsonian in 1975, and an example of a salvaged A6M from Saipan, so anyone with an interest can visit and compare for themselves the validity or otherwise of both Hughes’ claim and Horikoshi’s denial.

In 1980 Paul R. Matt answered the origins of the Zero theorist’s puerile speculations in this manner: ‘And that poor Mitsubishi OO Zero … it was the copy of so many aircraft it’s a wonder it ever flew incorporating so many foreign parts. The Hughes Racer did not escape the lookalike contest. The myth is so out of step that no further comment is necessary.’ Alas Paul, another four decades down the line, and the Internet abounds with ‘the conspiracy of copying’ devotees repeating the same old legends.¹⁰

Perhaps the closest foreign aircraft in appearance was the Gloster F.5/34, designed by H. P. Folland, two prototypes of which were built in response to an Air Ministry requirement for a fighter that could, ironically enough, operate in the hot climates of the Far East! When the first machine appeared (K5604) in December 1937 the resemblance was uncanny, being a allmetal cantilever, low-wing monoplane powered by a 9-cylinder Mercury IX air-cooled radial engine of 840hp (625kW). The wingspan was 38ft 2in (11.63m), shorter than the A6M, overall length 32ft (9.97m) longer than the Japanese machine. The powerful gun armament consisted of no fewer than eight 0.303in (7.7mm) calibre Brownings. She was credited with a speed of 316mph (508km/h or 275 knots). A second aircraft (K8089) appeared in May 1938 but no further development took place and the two machines became test beds until around 1941. Although Gloster had previously done work with Nakajima, there is no truth at all in the persistent stories that this aircraft had any connections at all with the A6M design.