Some Thoughts on
the Japanese A6M Series
Shipboard  Fighter 
by Dwight Cox  

I have recently seen a number of TV documentaries purporting to show historical facts about the most famous Japanese aircraft of the Pacific War.  One fallacy is that the Reisentoki was faster then the F4F-3 Wildcat fighter. The truth is that both the Model 21 and the Dash 3 fighters had approximately the same speed in level flight.  The F4F-4 was slower than the Model 21 due to the fact that 2 more .50 cal. MG's and additional armor plate was added to the Wildcat's airframe.

F4F-3 new pitot tube of later model.jpg




Another fallacy is that the Curtiss P-40 was designed to oppose the Zero.  Nothing could be further from the truth!  The Army Air Corps. noting that Curtiss P-36 performance was markedly inferior to the Bf-109E needed a new fighter to give Army pilots a fighting chance over the battlefield.

This need resulted in contracts for the Lockheed P-38, and Bell P-39 as well as the Curtiss P-40. Please note the advances in Japanese fighter technology were almost completely unknown in the West. Below 5,000 ft the P-36  could climb and turn with Zero but its' max speed of 311 mph was too slow. Replacing the radial engine with an Allison liquid cooled V-12 solved this problem, but at a cost of more weight without counting armor, self sealing tanks, fire extinguishers and .50 cal. MG's.  Both the P-39 and P-40 were 20 to 30 miles an hour faster than the Zero, particularly below 10,000ft.  Unfortunately the Army Air Corps' lack of foresight precluded the development of a high altitude supercharger despite Allison's request to initiate it's development.  The heavier weight of the American Army and Navy fighters gave the advantage in climb rate and maneuverability to the Zero. All of the American fighters, with the possible exception of the F2A Brewster Buffalo, could outdive the Zero because the control surfaces above 350 kts. became increasingly more difficult to manipulate.


One of the little known blunders of the JNAF was it's refusal to allow Mitsubishi to redesign the Zero to accommodate the larger diameter
Kasei 11.JPG Mitsubishi Kinsei radial engine (1560 hp).  This would allow the airframe to carry armor plate, self sealing tanks, fire suppression and heavier armament (no more .30 cal. popguns).  By the time the JNAF realized their mistake, they had run out of time.  The war ended without a single Kinsei powered Zero built.



Another little known fact is that the early model Type 99 20 mm cannon had a low muzzle velocity which resulted in something called ballistic drop.  To compensate for this characteristic, Zero pilots had to close to 50 to 75 yds., to ensure a kill.
Constant modification to the Type 99 cannon corrected the low muzzle velocity, low cyclic rate, and a change from a drum fed weapon to a belt fed weapon.  At the end of the war the Type 99 cannon was the equal of any nation's 20 mm cannon.   Prior to the Great Pacific War, Japanese metallurgists discovered a stronger alloy of aluminum that was later found by the American aircraft industry in 1944.  Mitsubishi made use of this alloy to improve the strength to weight ratio of the Zero's airframe.


Addendum: I have seen many claims on the internet that the 470 mph Do-335 Pfiel was the fastest piston engine fighter of WW2. Here are several fighters as fast or faster: P-47M, 470 mph. P-51H, 490 mph. P-82, 470 mph. Supermarine Spiteful, 483 mph. DeHavilland Hornet, 472 mph. Mitsubishi K-83, 470 mph (on American avgas). Ta-152H, 470mph. 

Photo sources include:

Mitsubishi A6M Zero

Grumman F4F Wildcat

Curtiss P-40 Warhawk

Mitsubishi Kinsei radial engine (1560 hp)

Type 99 20 mm cannon,



Here are some books I recommend for your perusal.
Eagles of Mitsubishi, Jiro Horikoshi.
Japanese Aircraft of the Pacific War, Rene J. Francillon.
Flying Guns Of World War 2, Anthony G. Williams and Dr .Emmanuel Gustin.
Warplanes of the Second World War Volumes 1 through 4, William Green.



 Dwight Cox


Dwight Cox has been been associated with NYMAS since the late 1980's.  He has lectured on various topics on Military Aircraft 1939-45 including Electronic Warfare in the ETO and PTO, Aircraft Piston Engines 1939-45,  Luftwaffe Air Transport Assets, Marine Air Support, Torpedo Bombers and Air Dropped Torpedoes, and in collaboration with Tom Wisker, Allied and Axis Aircraft Armament, and Allied Axis Jet Engines. Dwight has resided in Florida since April of 2000.


The author, Dwight Cox, at the Reading Air show sitting in a Curtiss SBC Helldiver.




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