# Mitsubishi A6M3 Type '0' Carrier Fighter in detail



## nuuumannn (Nov 24, 2013)

Hi Folks, since the Zero has been getting a bit of attention on the forum of late, I thought I be topical with this.

Few WW2 era aircraft raise as much contradictory discussion as the Mitsubishi Zero; in the first year of service it gained a “Myth of Invincibility” that was eventually torn down, resulting in a disregarding of the aircraft's capabilities owing to the fact that it stuck around for longer than it should have. Behind the legend however, it is often overlooked just how good this aircraft was; after all, an object does not earn such an accolade as “Invincible” by being merely average.

Jiro Horikoshisan's design for a Type '0' Carrier Fighter was original in execution and contrary to popular belief, owed little to foreign influence; it met the demanding requirements of the 12 Shi specification owing to an innovative structural design that was entirely modern and unique in an aircraft of its era. In order to meet the criteria, Horikoshi realised that weight saving was the key to his fighter's success and a newly developed aluminium alloy was used in its construction, commonly known as Extra Super Duralumin, which, like today's 7075 aluminium alloy had zinc as the largest alloying element.

Structurally, the Zero was designed for ease of construction and maintenance, with lightness at its core; the centre fuselage incorporating the cockpit was rivetted directly onto the wing centre. Just aft of the cockpit the rear fuselage unit was bolted on as a seperate structure. This enabled the aircraft to be broken down into easily transportable components. A novel aspect of the design for its time was the absense of a turtle back aft of the cockpit; it sat as a three piece unit atop the fuselage, allowing unrestricted visibility in almost all directions. Drag reduction measures were extensively undertaken to improve the aircraft's performance; the entire exterior structure was flush rivetted and all excrescences were designed to fold away flush with the exterior skin. 

When it first flew on 1 April 1939, the Zero was unmatched in performance among carrier based aircraft. After astonishing demonstrations of its endurance in the first year of the Pacific War its reputation was secure; there was no other fighter in the world that could carry out the missions its pilots did.

The Zero was however, ultimately a victim of its own success, as a determined enemy such as the Americans was always going to find a flaw and exploit it; the weight saving concept that was the design's raison d'etre was considered a weakness to the Allies, and was savagely exploited. In truth however, despite more powerful and better armed Allied fighters appearing in greater numbers than what the Imperial Japanese Navy could field, the Zero's virtues remained unmatched; because of its manoeuvrability at low speeds and low to medium altitudes it was a formidable adversary for the rest of the war and was never to be tangled with in a dog fight.

There has been some debate as to the structural strength of the aircraft, bearing in mind the proliferation of litening holes in as much structural support members as possible, even in the pilot's seat, but despite being lightly built, the integrity of the aeroplane was far from weak. The following was written by John Foster Jr., Managing Editor of “Aviation” magazine in an article describing the A6M3-32 in depth;

“This weight saving design would indicate that the craft is flimsily built, but such is not the case, for its strength compares favorably with many American built planes.”

Two different aircraft are used in this study; airworthy A6M3 c/n 3869, recovered from Babo airfield, Irian Jaya in 1991 and A6M3-22 c/n 3835 (although it is fitted with the rear fuselage of c/n 3844) acquired after surrender by the Royal New Zealand Air Force at Kara airstrip in southern Bouganville in 1945. The photographs of both these aircraft were taken in New Zealand; 3835 survives at the Auckland War Memorial Museum and 3869 was shipped to New Zealand especially for the 2010 Warbirds over Wanaka airshow, although a refuelling stop at RNZAF Base Woodbourne, near Blenheim enabled me to get close to it.

C/n 3869.







C/n 3835 today and how it appeared when it first went on display in the Auckland museum wearing a spurious colour scheme applied by the RNZAF.











C/n 3869 from different angles, highlighting the aircraft's svelte lines.






The Zero's wing comprised two spars of continuous 'I' sections that ran from tip to tip and were made up of two 'T' section extruded caps mated by a solid vertical web. The outer face of each spar was milled to sit flush with the outer wing skin.






Wing profile was designated Mitsubishi 118 and had a similar mean camber line to the NACA 23012 aerofoil that had been used in the Zero's predecessor, the A5M from the same design team; it was also used on the twin engined G4M land based bomber. Considerable care went into providing as clean a surface as possible. Underwing tie-down points are concealed by flush covers and spring loaded hand-hold plates sit flush with the surface when closed.






At the wing root the profile was NACA 2315 and the wingtip profile was NACA 3309. Washout was incorporated at the wingtips, which gave the Zero a comparatively low stalling speed. The Zero's centre of gravity was 0.075 inches forward of the main spar.






The fuselage breaks at a point just forward of the Hinomaru, where the aft fuselage attaches to the wing and fuselage centre section, which is rivetted directly onto the wing top surface, proving integral strength as a single unit. The top surface of the wing serves as the cockpit floor. The rear fuselage is a full monocoque and comprises a single keel longeron running its length and 22 'Z' section stringers supporting the frames, which are extensively lightened by litening holes around their circumference.






The after equipment bay was located directly behind the cockpit and the only access to this was by tilting the pilot's seat forward. Oxygen bottles and radio equipment was located in this section. The aircraft wears the markings of an A6M2 based at Kara, with the Commemorative Air Force Wings visible on the fin.






Stabilisers were two spar units with leading edges held in place by piano hinges. Control surfaces were aluminium framed and covered in fabric. The fin was built integrally with the rear fuselage. The elevators are fitted with in-flight adjustable trim tabs, whilst the ailerons and rudder has ground adjustable tabs only.






The Zero's Sumitomo Constant Speed prop was 10 ft 3 inches in diameter and was similar in design to the Hamilton Standard constant speed counterweight propeller. It was fitted with a fluid slinger ring for de-icing the blades. Intake up top of the cowl is for a two stage supercharger on A6M3 model. 3869 is powered by an R-1830 Twin Wasp as in your average DC-3/C-47, I suspect the prop is a Hamilton Standard unit, but what type I'm uncertain. The DC-3 is fitted with the 23E50 Hydromatic prop.






A6M3 is nominally powered by a 14 cyl Nakajima NK1F Sakae 21 of 1,130 hp. A6M2 a Nakajima NK1C Sakae of 940 hp. Bore is 5.12 in, stroke, 5.91 in, displacement 1,700 cu in. With an outside diameter of 45 inches, the engine was carefully cowled for drag reduction. The cowl comprises two easily removeable sections split horizontally, the oval plates concealing the release latches for opening the cowls for maintenance. The cowl flaps are manually operated.






More soon.


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## nuuumannn (Nov 24, 2013)

More Zero...

Oil cooler intake with grille covering, exhaust port and inboard undercarriage doors visible; note the yoke mechanism for their retraction. A jacket fitted to the oil cooler enabled hot air to be ducted to heat the carburettor.






Three piece canopy, which gave its pilots an excellent view outside; unique in a carrier fighter of its time and preceded in fighters in general only by the Westland Whirlwind. Note the headrest. Cooling louvres forward of the cockpit allow a flow of air ducted within the cowl to cool powerplant auxiliary components, fitted aft of the engine. The absense of radio aerials in the aft canopy section is noteworthy.






Windshield and panel detail of the forward fuselage area. Note the flush rivetted skin work. The rectangular door flush with the skin at right conceals the crew oxygen supply port and exterior content gauge. The red arrow points to a latch for retractable foot steps to enable the pilot to reach the cockpit without standing on the top wing skin, which was of light gauge aluminium and did not suffer wear too well.






Canopy in the opened position. DF loop aerial visible inside canopy; the mast was for a low frequency transmitter for communicationg by morse with the home base. The canopy opening latch can be seen as a small silver acorn on the sliding section's forward rim, the canopy being able to be opened from both the inside and out; there are four holes in the rail that the latch pin can slot into. The screws along the bottom ledge of the canopy fasten a plywood support on its inner rim.






Hand hold pins for access to the cockpit. All protruding items are spring loaded and are designed to fit flush with the exterior skin to aid drag reduction. These are fitted with metal mushroom head plates on their interior face to prevent damage to floatation devices located in the fuselage cavity aft of the cockpit.






Cockpit entry steps that pop out of the fuselage on pulling down the vertical lever marked with the red arrow at left; arrows indicate where to put your feet. A very neat installation and avoids aircrew standing within the red area marked on the wing above the flap. Handhold pegs visible below the canopy sill.






Pilot's eye view through the windshield. Gunsight missing, replaced by Garmin GPS.






Plenty of detail in this view of the cockpit. Note the location of the gun butts and their cocking handles, reminiscent of Great War fighters. Cockpit guns are 7.7mm Type 97 machine guns and are electrically synchronised to fire through the propeller arc. Guns are designed to fire at 600 rpm, but most likely less as a result of synchronisation. The cylindrical device below the panel is oxygen indication, the red handle at right actuates the cowl flaps. Note also the twine winding around the wooden joystick. Whilst the rudder bar could be adjusted by turning the star-shaped handle, the seat could only be moved up or down.






When I first saw this I thought this was a wiring diagram - having studied it a bit more, it appears to be a fuel transfer diagram.






Left hand cockpit sill detail; throttle console with power lever with gun selector lever attached, mixture and prop condition lever visible. Gauges on sill below electrical switch box are from front; outside air temperature, fuselage fuel tank and wing fuel tank contents gauges. Note the primer and magneto switch on the lower left of the forward panel. 






Instrument panel gauges are a mix of American and Japanese; from top left to right are exhaust temperature, clock and ASI, compass, VSI, RPM and oil temp/fuel/oil pressure three-in-one gauge. Bottom left to right; turn and slip, ALT, cylinder head temp, ammeter, manifold pressure gauges. The handle at lower right opens the oil cooler shutter. The latch at mid left locks the canopy.






Right hand cockpit detail includes oil shutter and cowl flap handles and Russian radio and morse key - Cyrillic characters read PRD SMPL, PRD P/DPL, PRM P/DPL. The circular device at top right operates the tail hook, although it is inoperable in this aircraft. The red topped handle is a wobble pump for emergency hydraulic pressure for lowering flaps and undercarriage. Note also the obligatory rag for wiping oil spat out of the engine off the fuselage, as the guys were doing when I arrived!






More soon.


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## nuuumannn (Nov 24, 2013)

More Zero.

Right hand wing from the cockpit. The two sets of white writing indicate the refuelling points in the wing. The A6M3 has five; the fifth being ahead of the cockpit. In the A6M3 22 the wings were lengthened over the 32, which had clipped wings. Extra tankage was fitted to the 22 to rectify range deficiency of the 32. Also visible is the undercarriage down indicator on the leading edge. Inboard formation light visible within red bordered area above flap.






Left hand outer wing. One of the panels enclosing the wing tip hinge points can be seen near the camera. Note the formation light in the Hinomaru and aileron actuator. The Zero's wing area was 241.54 sq ft (22.44 m²); its designers endeavoured to reduce its wing loading to below 21.5 lb/sq ft (105 kg/m²). This combined with a relatively low stalling speed gave the Zero exceptional manoeuvrability at low speed.






Folding wing tip mechanism from the wing of a disassembled A6M in a hangar at Duxford. Of note is the two single piece wing spars that ran from tip to tip in green and fabric aileron. The image has been shown on its side as the wing was sitting leading edge down.






Underwing detail including lowered flap and wing gun panelling. Flaps are hydraulically actuated, with a maximum setting of 60 deg, although 40 deg position provides the best glide angle. Bulges housing the magazine visible, along with the cannon opening in the leading edge.






A single 20 mm Type 99 cannon is mounted in each wing. This preserved example is on display at the Yasukuni Shrine in Tokyo. Cannon fires at a rate of 100 rpm, earlier variants fired at only 60 rpm.






Data plate information painted on the left hand rear fuse and US rego with decidedly temporary 'X'. The data plate reads from the top; Type: Zero Type Carrier Fighter Model 23, Manufacturer's Number: Mitsubishi No. 3869, Unit attached: (aircraft type and serial shown in place of this information)






Solid rubber tailwheel characteristic of carrier aircraft of the time. Note the castoring lower section. The tail undercarriage is retractable by a single hydraulic shock strut that also provides cushioning, whose lower attachment point can be seen. The tailwheel is steerable via cables running from the rudder pedals and can castor in a 60 deg arc, but this can be overridden by the pilot giving the rudder pedals a sharp prod. The leg can be locked true during take-off and landing.






Left hand main undercarriage leg with uplock ring visible at the extreme bottom of the leg. Main undercarriage is hydraulically actuated; once a weight-on-wheels condition is in place, a cable from the right hand leg runs to a latch mounted below the undercarriage selector lever on the right hand side by the pilot's leg in the cockpit, which provides a physical barrier to prevent the inadvertent retraction of the undercarriage on the ground. 






Right hand main undercarriage leg of 3835. Note the upper hinged portion of the leg door and absense of a wheel cover. Its oleo has collapsed, causing its scissor linkages to sit at an odd angle – pressurised oleo compresses by 3.5 inches. Brakes are hydraulic drum type and are operated by pressure on the upper rudder pedals. There is no park brake. Each wheel and brake assembly weighs a mere 28 lbs.






Left hand inboard undercarriage bay and door. Note the hinged triangular after portion of the crescent door and its actuation mechanism in black. The undercarriage bays are mounted forward of the forward spar. Loading from the legs is transmitted to a spanwise spar attached to both forward and aft spars by built up sections of heavy material.






Lastly, two images of c/n 3685 starting up and departing WB for Wanaka and an appreciative crowd.











Thanks for looking.

Reactions: Bacon Bacon:
2 | Like List reactions


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## Wayne Little (Nov 25, 2013)

Nice, will have to digest these some more...


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## Rogi (Nov 25, 2013)

Worth a pound of Bacon  fantastic!


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## meatloaf109 (Nov 25, 2013)

Thanks for posting!


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## Gnomey (Nov 25, 2013)

Good stuff!


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## vikingBerserker (Nov 25, 2013)

Excellent! It amazes me that as advanced it was at the time, how few gauges were in the cockpit.


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## Airframes (Nov 28, 2013)

For some strange reason, I'm one of the very few who have no interest in the type, but what a great set of pics Grant!
And I can now see just how advanced it was for its day, even down to GPS in the cockpit .... (just kidding)!


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## VBF-13 (Nov 29, 2013)

What a look at this one! Thank you!


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## Wildcat (Nov 29, 2013)

Great posts! Many thanks


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## nuuumannn (Dec 1, 2013)

Thanks, guys.  

I remember the day the aircraft landed at WB; I was at home and had just put my daughter down for her afternoon nap. Our house is quite close to the flight path for Omaka airfield and I heard the sound of a radial grumbling away, but it didn't sound like the usual Nanchangs or Harvards that frequent the area, so I ran outside only to see a Mitsubishi Zero go streaking past! I made my apologies to the Long Suffering and jumped in the car to follow it to discover it had landed at work, so off I went to go sit in the cockpit of a Zero!.


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## bent metal (Jun 19, 2014)

Cool stuff!


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## Wurger (Jun 19, 2014)

I echo the post above.


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## Zippythehog (Feb 5, 2017)

Great post. Thank you for sharing. Building Tamiya's excellent 22 so a timely discovery.


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## Micdrow (Feb 5, 2017)

Good stuff, many thanks!


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## MiTasol (Feb 8, 2017)

Airframes said:


> For some strange reason, I'm one of the very few who have no interest in the type, but what a great set of pics Grant!
> And I can now see just how advanced it was for its day, even down to GPS in the cockpit .... (just kidding)!



And the Russian morse key!


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