Debunking the myth: the rise and fall of the Zero By Fred Lane

(This article was first published in NOCN 84, 1 March 2011.)

One of the more highly trumpeted intelligence finds in WW II was a near-new Mitsubishi Zero A6M2 Type 0 Model 21 (serial number 4593) that crashed during its first operational flight on 4 June 1942. One of a three-plane section from HIJMS Ryujo, the Zero lost oil pressure after taking ground fire during one of the Dutch Harbor raids (Aleutian Islands, Alaska). Its pilot, 19 years-old Petty Officer Tadayoshi Koga, died attempting a precautionary landing on a nearby island.

The Akutan Zero

The Japanese nominated Akutan Island, 25 miles east of Dutch Harbor, as an emergency landing site and had a SAR submarine standing by. Unfortunately, the long, flat field chosen by Koga for his wheels-down landing was deceptive. Under its inviting-looking grassy-green flat surface lay a treacherous water-logged muskeg bog. His wheels dug in and he somersaulted as he touched down.

A USN salvage team examines the Akutan Zero.

Perhaps as befits such a famous icon, the history of the Japanese Zero brings with it almost as many controversies and myths as agreed facts. For instance, when 27 Chinese fighters challenged 13 Zeros in September 1940, did the Zeros destroy all 27 without loss? Was the Akutan Island Zero the first flyable A6M2 to be captured? Did American aircraft engineers quickly apply novel design features discovered in the Akutan Zero? Were tactics to defeat the Zero first derived from simulated battles between American fighters and the Akutan Zero? Was the restored Akutan Zero 100 per cent “made in Japan”? Was the Zero faster than its American contemporaries?

LCDR Eddie R Sanders USN flies the Akutan Zero in American colours, Sand Diego, September 1942.

Definitive fighter

Designed by Jiro Horikoshi, the Japanese Navy’s Mitsubishi A6M2 Type 0 Model 21 was the definitive WW II Japanese fighter. It could make a respectable 288 knots at 15,000 feet and climb to 20,000 feet in seven and a half minutes. This was better than any other Pacific theatre aircraft at that time. When they bombed Pearl Harbor, the Japanese had only 328 Zeros in front line units but wartime factories delivered thousands more (Francillon 1995, p. 362-378). More Zeros were produced than any other Japanese WW II aircraft. Mitsubishi constructed 3879, Nakajima built 6215 and other firms manufactured 844 trainer and floatplane variants (Okumiya et al, 1957 p. 350). The basic design never changed, but later production runs incorporated modifications such as wingtip folding, more powerful engines and stronger bomb racks.

 

Mitsubishi Zero A6M2 Type 0 Model 21.

By the time of the Dutch Harbor raids, the Zero possessed a fearsome reputation. First flown in April 1939, it proved to be agile, lightweight, hard-hitting and versatile. Except for Nationalist China’s Polikarpov I-16, the Zero’s two 20 mm cannon and two 7.7 mm machine guns out-gunned every other fighter in the Pacific Theatre.

Long range

The Zero’s 1675 nm ferry range was far superior to any other fighter and many contemporary bombers. The Armstrong Whitworth Whitley Mk V, a twin-engined bomber introduced to the RAF in 1939, had a range of only 1,430 nm (Angelucci, p. 262). If Supermarine Spitfires had the Zero’s ferry range, they could have easily flown the 1140 miles from London to Malta without risking valuable aircraft carriers to deliver them in WW II.

 

The Chongqing stoush

As early as August 1940, Zeros routinely flew combat round trips of 1000 miles or more, deep into China. They gained a reputation as superb dogfighting machines. For instance, over Chongqing (then Chungking), the inland seat of the Nationalist Government, on 13 September 1940, the Chinese sent 27 Russian-built Polikarpov I-15 and I-16 fighters aloft to mix it with 13 Zeros. Many claim that all 27 Chinese fighters were destroyed, without a Zero lost, but this possibly includes a Polikarpov pair that crashed into a mountain during an evasive manoeuvre and unspecified others whose pilots might have bailed out without being hit (e.g., Okumiya et al, 1957 p.14).

The Russian-built Polikarpov I-16 first flew in December 1933, the first monoplane fighter with retractable undercarriage, dimensions 9.2 x 6.1 x 2.6m, weight 3110-4034 lb (1414-1834 kg). M62R Shvetsov 9-cylinder radial, 1000 HP. Two 7.62 mm guns and two 20 mm cannon with 120 rpg.

 

On the other hand, although aircraft claims can be easily exaggerated (e.g., Ford, 2007 Preface ix-xiii), a small number of authors claim that “actual Chinese losses were 13 planes” (e.g., Ford, 2007 p. 28). This might well suggest an impossibly large and unresolvable discrepancy, but all agree that, in this action:

a. the Zeros initially were outnumbered more than 2:1;

b. Zeros were hit, but none lost in the melee; and

c. the disaster caused the Chinese to order cessation of all aerial combat.

Whether the Zeros destroyed only 13 or all 27 Chinese fighters in the Chongqing battle might be of little import, compared with the huge strategic victory that left the Zeros masters of the China sky. The Chinese fled the fight (Ford, 2007 p. 28; Okumiya et al, 1957 p.14).

 

Other Zero captures

The Akutan Zero was not the first of its type to have been captured. On 26 November 1941, two lost their way, ran short of fuel and executed precautionary landings on a Leizhou Peninsula beach. Abutting the Chinese mainland near Hainan Island, this peninsula was in Chinese hands. By 1942 these lightly damaged Zeros were being rebuilt into one machine (serial number 3372).

Another (Model 21, serial number 5349) had been retrieved from Australia’s Melville Island. Flown by Petty Officer Hajime Toyoshima, he was returning to HIJMS Hiryu from one of the first Darwin bombing raids on 19 February 1942. Again, ground fire led to oil pressure failure, but this time his engine seized and shed its propeller. He force-landed on the nearest piece of dirt, Melville Island. Toyoshima became Australia’s first Japanese prisoner of war. He died taking a leading role in the 1944 Cowra POW camp breakout attempt.

Parts of another Zero had been recovered after a forced-landing near Cape Rodney, 100 miles SE of Port Moresby on New Guinea’s south coast. Unfortunately, the salvage crew roughly severed its wings. They also souvenired many of its important instruments and other small parts before they could be formally examined.

 

Weak opposition?

Perhaps the Zeros were lucky in China and elsewhere, facing poorly trained pilots in obsolete aircraft? When they met “proper” pilots in “proper” aircraft, would they not get their comeuppance?  Evidently not. For instance, according to a fairly reliable Japanese source, 36 Zeros and other aircraft attacked Colombo and Trincomalee, Sri Lanka (then Ceylon), in early April 1942. They were met by a mixed bag of about 60 RAF and RN aircraft. No less than 27 British aircraft were claimed by the Zeros in this sortie, including 15 Hawker Hurricanes and four Fairey Fulmars, for the loss of just one Zero (Okumiya et al, 1957 pp. 97-102). Others, (e.g. Gill 1968, pp. 17-20) claim 33 Japanese bomber and fighter aircraft were shot down for the loss of 23 Hurricanes and seven Fulmars. It matters little whether Gill or Okumiya was more accurate in the aircraft count. Once more, the Zero and Japanese naval pilots demonstrated their overwhelming superiority over both RAF Hurricanes and RAF pilots, despite their impeccable Battle of Britain credentials.

 

Indian Ocean sweep

The Sri Lankan and Indian raids were part of that most profitable Indian Ocean sweep by VADM Chuichi Nagumo’s powerful aircraft carriers HIJMS Akagi, Ryujo, Hiryu, Soryu, Shokaku and Zuikaku. Having dusted up Darwin earlier, on 19 February, Nagumo repeated the exercise on 3 March, sinking about 30 ships at Tjilatjap, on the south coast of Java. Entering the Bay of Bengal in early April, Nagumo not only put ADML Sir James Somerville’s Eastern Fleet to flight, but also netted the RN aircraft carrier HMS Hermes, the two cruisers HMS Dorsetshire and Cornwall, the RAN’s HMAS Vampire and 30 other naval, naval auxiliary and civilian vessels, aggregating 151,000 tons; all for negligible Japanese losses (Fuchida and Okumiya, 1958 ch. 2; Gill, 1968 p. 22).

 

The unknown fighter

Virtually unknown to the allies before Pearl Harbor, the Zero entered the Pacific fight with a better than 12:1 kill ratio. Major Claire Lee Chennault (later LGEN USAF) commanding the mercenary “Flying Tigers” with Curtiss P-40 Tomahawk fighters in China, had warned about the Zero’s performance, but analysts in the USA Department of War (later Department of Defence) regarded these reports as “arrant nonsense” and “aerodynamic impossibilities” (Handel, 1989). Chennault correctly recommended that contemporary American fighters should never attempt to dogfight the Zero, but to attack from above and maintain speed. If attacked by a Zero, the pilot should evade by diving steeply at full power and rolling right (Loomis, 1961 pp. 47-48).

 

Tha Aleutians campaign

What was this valuable new Zero doing in Alaska’s Aleutian chain in June 1942? Spurred by the 18 April 1942 Doolittle raid and the Battle of the Coral Sea, 7-8 May, the Japanese Combined Fleet Headquarters and Naval General Staff dusted off plans for a major offensive, the invasion of Midway Island. They looked forward to the USN Pacific Fleet intervening (Fuchida and Okumiya, 1958 pp. 41-46). While VADM Chuichi Nagumo deployed only 20 surface warships for his highly successful Pearl Harbor attack, ADML Isoroku Yamamoto had no fewer than 128 surface warships, plus troopships and support vessels for his complex Midway operation (Smith, 2007 pp. 14-17).

The light carriers Ryuko and Junyo and a small task force opened the battle during the early morning of 3 June with raids about 1500 miles north of Midway on Dutch Harbor and Adak, together with invasions of Kiska and Attu Islands, all in the Aleutians, 6 and 7 June.

As well as extending the Japanese reach up the Aleutian chain, Yamamoto aimed to draw American ships away from Midway, then crush them with a seven-battleship force in a “great decisive battle” as they returned (Fuchida and Okumiya, 1958 p. 49; Smith, 2007 p. 7-10). Brilliant decryption and misinformation intelligence work, chiefly by the USN’s CMDR Joseph Rochefort in Hawaii and Australian CMDR Eric Nave in Melbourne and Brisbane, allowed ADML Nimitz to ignore the Aleutian feint and instead concentrate on the Midway-bound thrust (Smith, 2007 pp. 31-50).

 

Midway

One American (Yorktown) and four Japanese (Akaga, Kaga, Soryu and Hiryu) fleet carriers went to the bottom in this Battle of Midway, the “pivotal point of the Pacific War” (Okumiya et al, 1957 p. 121; Smith, 2007 pp. 328-329). Worse, the Japanese never had the infrastructure to replace their highly trained naval aircrew and staff officers lost in the Coral Sea and Midway battles (Fuchida and Okumiya, 1958 p. 157). The resulting lack of numbers and experience led almost directly to debacles such as the 19-20 June 1944 Great Marianas Turkey Shoot, when the Japanese lost 400 or so aircraft to USN carrier fighters, and the employment of four almost empty aircraft carriers as sacrificial bait to lure ADML Halsey’s strong Third Fleet away from San Bernadino Strait a few days later (Morison, 2001; Okumiya et al, 1957 pp. 256-65; Smith, 2007; Tillman, 2005).

 

Secrets revealed

The Akutan Zero’s secrets were revealed only after a remarkable series of events. Firstly, the Aleutians are noted for poor flying weather. Typical low cloud with poor visibility greeted the Japanese aircraft over Dutch Harbor on 3-4 June. True to form, the “Aleutian clag” persisted for weeks, so it was not surprising that, although only a short distance from Dutch Harbor, it was five weeks before a passing US Navy PBY Catalina sighted the upturned Zero on 10 July. After three attempts, the USN finally salvaged the machine. They eased the upside-down Zero onto a skid, dragged it out with a tractor and righted it back in Dutch Harbor. Crated and delivered to Seattle on 1 August, it was transhipped to NAS North Island, San Diego, where it was restored to flying trim by 20 September (Technical Aviation Brief #3, 1942).

The aircraft engineers found a 19 February 1942 manufacturing date stamp confirming the machine was a valuable late A6M2 Model 21. Some reports say the Sumitomo propeller  damaged beyond repair; others say the propeller was beaten back into shape. Yet others show it was a direct copy, built under licence, of a readily available Hamilton Standard propeller that was easily substituted for the damaged Japanese version (www.pacificwrecks.com, December 2010). Engine spares presented little problem. The twin-row 14-cylinder engine was a close relative of the widely-licensed French Gnome-Rhone Mistral Major.

Akutan Zero flies again

LCDR Eddie R. Sanders USN flew the Akutan Zero for the first time in American colours on 20 September 1942. As a tribute to the skill of the NAS North Island aircraft engineers and the Zero’s built-in ease of maintenance, he managed 24 test flights in 25 days. It was during these flights that Sanders confirmed the Zero’s excellent low speed manoeuvrability but he also documented its amazingly poor rolling performance at moderately high speeds. The Zero had excellent roll control below 200 knots, right down to the stall, but the large servo-tab ailerons became progressively sluggish and almost impossibly heavy above 250 knots. Reinforcing Chennault’s observations, he also found that the float-type carburettor starved the engine of fuel under negative G. All this information, with combat recommendations, were relayed to the fleet shortly after Sanders’s first flight (Technical Aviation Brief #3, 1942). Not long after, he was rewarded with the feedback, “It works”.

After the test flights, the Akutan Zero was matched in simulated battle with a large number of different WW II American USN and USAF aircraft types and tactics. These were flown chiefly from NAS North Island CA and NAS Anacostia/Bolling AFB, Washington, DC.

“Thach weaves” and other gimmicks were sometimes credited with defeating the Zero, but nothing seems to have been more effective than the simple old WW I tactic of staying in battle formation and gaining a potential energy advantage in the form of a height/speed edge over the enemy. This was amply reinforced by the Akutan Zero’s test data from simulated adversary battles. It remains true in dogfighting today.

There were some less than well-informed claims that these Zero evaluation trials were responsible for massive design changes in those Pacific Ocean scourges, the Vought F4U Corsair and the Grumman F6F Hellcat (Okumiya et al, 1957 p.179). In fact, the Akutan Zero appeared far too late for any major weight-saving or other influence on these aircraft designs.

The first “Hosenose” F4U production model flew in June 1942 and deliveries to USN and USMC squadrons commenced towards the end of that year. The Corsair’s gestation was laboured, not solely because of weight considerations but mainly due to armament modifications. These required the cockpit to be moved 32 inches (81 cm) aft and the fuel tanks re-positioned. Despite its low wing loading, early production Corsairs, with their comparatively poor over-the-nose visibility, vicious torque stalls and toey undercarriage, were condemned as too difficult to deck land. (US Marines, however, found a way. USMC Corsairs, operating from tiny escort carriers were most effective. Their cheaply-modified Corsairs helped the Allies turn the tide in 1950 at Inchon and Pusan in Korea.)

Thruelsen, in his authoritative Grumman story, notes that excess weight was a major consideration long before the Akutan Zero was found in 1942. In fact, a weight-saving program was a feature of the old Grumman F4F Wildcat, one version of which was flying with the RN as early as December 1940. This owed nothing to the lightweight Zero, but more to the prospect of having to operate these fighters from small escort carriers (Thruelsen, 1976 p. 181).

The first Grumman F6F Hellcat flew on 26 June 1942 (Angelucci, 1990 p. 237; Thruelsen, 1976 p. 382) months before the Akutan Zero’s first test flight in USN colours. Regarding the Zero’s influence on the Grumman F6F Hellcat design, as stated fairly clearly (Thruelsen, 1976 p. 194):

The most important claim that could be made for the Hellcat…was that it outperformed the best of the Zeros in every department except range. And the Hellcat needed few modifications and practically no structural changes during its production lifetime.

 

Grumman F6F Hellcat (10.24 x 13.06 x 3.99), weight 9238-12598 lb (4199-5726 kg). Pratt & Whitney Double Wasp 2000 HO. Max 330 kn; ferry range 1330 nm. Six .5 inch guns with 400 rpg or2 x 20 mm cannon with 225 rpg and 4 x .5 inch guns with 400 rpg. Six x 5 inch RP, or 4000 lb bombs/Mk 13 torpedo.

 

While the Akutan Zero might have helped to modify and confirm certain fighter tactics, all the major structural F4UCorsair and F6F Hellcat design decisions had been made long before that Zero rolled out of its Mitsubishi factory in February 1942.

How “genuine” was the restored Zero? If it was restored in NAS North Island to a “better-than-new” condition, then the derived test data might carry a positive bias. Similarly, if the somersault and subsequent rough handling was sufficient to warp the airframe or severely damage the engine, then the test data might under-value the production aircraft’s true potential. Perhaps the best estimate of this may be to quote LCDR Sanders when author Jim Rearden asked was “the repaired airplane 100 per cent” genuine? Sanders’s reply was “about 98 per cent” (Rearden, 1997). Unfortunately, Rearden seems to have failed to resolve which specific parts were not genuine.

Also unresolved is the relatively minor issue of whether all propeller blades were beaten back into shape, or if one propeller blade or even an entirely new Hamilton Standard three-bladed propeller was substituted in the Akutan Zero at NAS North Island.

Regarding speed, the Zero was certainly fast and nimble, but it had flaws. What was the sense in having a fast airframe if it could not roll rapidly over 250 knots?  Read the interesting discussion defining some speed parameters by Richard Dunn at http://www.warbirdforum.com/zerodunn.htm for partial answers.

What is clear is that the investigation of the Akutan Zero, if nothing else, destroyed the Zero’s aura of invincibility. The American tests put to the sword dozens of swirling myths, rumours and exaggerations. Most of the few remaining myths were dispelled when the new Grumman F6F Hellcat was first deployed in action 31 August 1943, and the remainder were firmly nailed after the 19-20 June 1944 “Great Marianas Turkey Shoot”.

The Zero entered WW II as world-beater. It ended the war ignominiously, as a kamikaze vehicle. The Philippines-based Naval Air Group 201 introduced the Zero as a kamikaze following a decision by VADM Takijiro Onishi at Mabalacat Airfield (later Clark AFB), 19 October 1944 (Okumiya et al, 1957 pp. 266-282).

In a similar vein, the ultimate demise of the famous Akutan Zero was also tragically anti-climactic. Taxying out for a training flight in February 1945, a Curtis SB2C Helldiver over-ran it and “chopped the fuselage to pieces”. The pilot was uninjured, but only a small number of instruments and other odd pieces are known to remain.

 

References:

Angelucci, E. The Rand McNally encyclopaedia of military aircraft. Crescent books: New York. 1990.

Ford, D. Flying Tigers: Claire Chennault and his American volunteers, 1941-1942. Harper Collins: Smithsonian Books, 2007.

Francillon, R.J. Japanese aircraft of the Pacific War, Mitsubishi A6M Reisen (Zero Fighter). Naval Institute Press: Annapolis. 1995.

Fuchida, M. and M. Okumiya. Midway: The battle that doomed Japan. United States Naval Institute: Annapolis. 1958.

Gill, G.H. Royal Australian Navy, 1942-45 (1st Edition). Australian War Memorial: Canberra. 1968.

Handel, M. I. War, strategy, and intelligence. Frank Cass: London, 1989.

Loomis, R.D. Great American fighter pilots of World War II. Random House: New York, 1961. Morison, S.E. New Guinea and the Marianas, March 1944-August 1944. vol. 8 of History of United States naval operations in World War II. University of Illinois Press: Champaign. 2001.

Okumiya, M., J. Horikoshi and M. Caidin. Zero: the story of the Japanese navy air force 1937-1945. Cassell and Company: London. 1957.

Prange, G.W. At dawn we slept: The untold story of Pearl Harbor. McGraw-Hill: New York. 1981.

Smith, P.C. Midway: Dauntless victory. Pen and Sword Maritime: Barnsley. 2007.

Technical Aviation Brief #3, Performance and characteristics trials, Japanese fighter, Aviation Intelligence Branch, Navy Department (4 Nov. 1942).

Thruelsen, R. The Grumman story. Preager Publishers: New York. 1976.

Tillmann, B. Clash of the carriers. The true story of the Marianas Turkey Shoot of World War II. Penguin Group: New York. 2005.

 

Websites:

Aiken, D. response 21 February 2001, http://www.j-aircraft.com/faq/pearl_harbor.htm.

Rearden, J. Koga’s Zero: An enemy plane that saved American lives. Invention and technology magazine. Fall 1997, Vol 13/2. http://www.americanheritage.com/articles/magazine/it/

1997/2/1997_2_56.shtml.

http://www.j-aircraft.com/faq/pearl_harbor.htm

http://www.warbirdforum.com/zerodunn.htm

http://www.pacificwrecks.com/aircraft/a6m2/4593.html (December 2010)

http://en.wikipedia.org/wiki/Akutan_Zero (December 2010)

 

Mitsubishi Zero Type 0 A6M2 Model 21.

Wing span: 39.38 ft (12 m); Length: 29.73 ft (9.06 m); Height: 10 ft (3.05 m); Weight Empty: 3703 lb (1680 kg); Weight loaded: 5313 lb (2410 kg); Performance: V (max) 356 knots, Max cruise: 288 Knots, Service ceiling: 32,810 ft; Range: 1675 miles. Manual wing tip folding was introduced on later versions.

Powerplant: Nakajima NK Sakae 12, (Mistral copy, built under licence from Gnome-Rhone) 14 cylinders air cooled radial, 940 hp, driving a three-bladed variable pitch Sumitomo propeller. The A6M3 Type O Model 32, introduced in April 1942, had an 1130 hp Sakai 21 engine with a two-speed supercharger, but only 343 were built.

Drop tank: 330 L (72 gallons)

Armament: Two x 20 mm cannon (60 rpg), 2 x 7.7 mm machine guns (500 rpg), 264 lb (120 kg) bombs, or one fixed 551 pounds (250 kg) bomb in the kamikaze mode.

 

Grumman F4F-4 Wildcat. (The G-36 Martlet was one export version, FM-1 and FM-2 were F4Fs built by eastern Aircraft.)

Wing span: 38 ft (11.6 m); Length: 28.75(8.8 m); Height: 11.8 ft (3.6 m); Weight empty: 5760 lb (2613 kg); Weight loaded: 7952 lb (3560 kg); Performance: V(max) 422 knots; Max cruise 280 knots; Service ceiling 34,900 feet; Range 770 miles. All but the very early production aircraft had manual wing folding.

Powerplant: Pratt and Whitney R 1830-86 Twin Wasp 14 cylinders, air cooled radial, 1200 hp driving a three-bladed variable pitch propeller.

Late production F4F-4s could carry two 58-gallon drop tanks.

Armament: six .5 inch machine guns (240rpg), 200 lb bomb.