The Zero Fighter

[oldpop2000]

One of the most discussed, written-about and investigated fighters of WW2 was the Mitsubishi A6M2 fighter. There three major versions of it: the Model 21, Model 32 and Model 52. There was also a version built as a float plane. I  am starting this thread and would like to know if anyone is actually interested in the fighter.

[seawolf]

Apr 27, 2023 7:18:33 GMT -6 oldpop2000 said:

One of the most discussed, written-about and investigated fighters of WW2 was the Mitsubishi A6M2 fighter. There three major versions of it: the Model 21, Model 32 and Model 52. There was also a version built as a float plane. I  am starting this thread and would like to know if anyone is actually interested in the fighter.

I think there's slightly more variance in the development, the zero has, just in production line combat variants-
The A6M2a (Model 11) was the first 64 models, with non-folding wingtips
The A6M2b (Model 21), 1540 airframes, with two derivatives: A6M2-N "Rufe" floatplane(~325 airframes), and the A6M2-K two-seat trainer(~516 airframes)

The A6M3 (Model 32), which introduced a supercharger, but had no folding wingtips and reduced much range, 560 Airframes

The A6M3 (Model 22), which retained the supercharger, but reintroduced a longer range and folding wingtips.  Official production data appears to be unavailable, but from the start of the A6M5 series there were at least 900 airframes

The A6M5 (Model 52), which introduced shortened wings and once again got rid of the folding wings, making it a compact fighter and the fastest variant.
The Model 52 had many subvariants, including:
The A6M5a (Model 52a), with drum fed cannons and faster diving speeds
The A6M5b (Model 52b), which introduced cockpit armor and a 50 calibre browning derivative.
The A6M5c (Model 52c), which strengthened the 52b's cockpit armor and added 2 13.2mm Type 3 machine guns, as well as rocket launchers, to better intercept B-29 bombers.
And lastly, A6M5-S, which was a fairly unsuccessful night fighter version

In 1945, the A6M7(Model 62 and 63) was introduced to combat as a dive bombing capable version with up to a 500kg bomb, as a reinforced version of the latest A6M5c fighter

The A6M8(Model 64) was a significantly modified aircraft, with a much larger power plant that might have enabled it to keep up with late war US fighters better, but it never made it to the production lines due to the devastation of Japanese industry in 1945.

[oldpop2000]

Apr 27, 2023 15:23:34 GMT -6 seawolf said:

Apr 27, 2023 7:18:33 GMT -6 oldpop2000 said:

One of the most discussed, written-about and investigated fighters of WW2 was the Mitsubishi A6M2 fighter. There three major versions of it: the Model 21, Model 32 and Model 52. There was also a version built as a float plane. I  am starting this thread and would like to know if anyone is actually interested in the fighter.

I think there's slightly more variance in the development, the zero has, just in production line combat variants-
The A6M2a (Model 11) was the first 64 models, with non-folding wingtips
The A6M2b (Model 21), 1540 airframes, with two derivatives: A6M2-N "Rufe" floatplane(~325 airframes), and the A6M2-K two-seat trainer(~516 airframes)

The A6M3 (Model 32), which introduced a supercharger, but had no folding wingtips and reduced much range, 560 Airframes

The A6M3 (Model 22), which retained the supercharger, but reintroduced a longer range and folding wingtips.  Official production data appears to be unavailable, but from the start of the A6M5 series there were at least 900 airframes

The A6M5 (Model 52), which introduced shortened wings and once again got rid of the folding wings, making it a compact fighter and the fastest variant.
The Model 52 had many subvariants, including:
The A6M5a (Model 52a), with drum fed cannons and faster diving speeds
The A6M5b (Model 52b), which introduced cockpit armor and a 50 calibre browning derivative.
The A6M5c (Model 52c), which strengthened the 52b's cockpit armor and added 2 13.2mm Type 3 machine guns, as well as rocket launchers, to better intercept B-29 bombers.
And lastly, A6M5-S, which was a fairly unsuccessful night fighter version

In 1945, the A6M7(Model 62 and 63) was introduced to combat as a dive bombing capable version with up to a 500kg bomb, as a reinforced version of the latest A6M5c fighter

The A6M8(Model 64) was a significantly modified aircraft, with a much larger power plant that might have enabled it to keep up with late war US fighters better, but it never made it to the production lines due to the devastation of Japanese industry in 1945.

Thank you, I appreciate the information you have provided, it makes it easier for me to continue. I will reference this post, if you have no problems with that,

[oldpop2000]

The story of the Japanese Zero starts in the War in China. The Japanese had been flying Nakajima biplanes and they were not adequate. They started to use the Mitsubishi A5M4 Type 96 fighter. This plane was all metal, open cockpit, single-seat monoplane with a fixed undercarriage and powered by either a Mitsubishi 730 hp or a Nakajima 750 hp radial engine. Her speed was about 270 mph and a range of 460 miles. She was armed with two 7.7mm machine guns. However, she did not have the range to provide escort to the G3M and G4M1 bombers. This is the beginning of the requirements that started the development of the A6M2.

The new fighter was to have long range to provide full escort to and from the target. She would still be a naval aircraft and would have to operate from carrier decks and could be stowed in hangers. The carrier specifications were the limiting factors. She had to have a wingspan of less than 39ft 4in, a short take-off length which was about 229 ft. 8in. into a wind over the deck of 39.37ft/sec. Landing specifications were 574.2ft with no hard wind. The landing speed had to be less than 58knots.

The new fighter had to have a top speed over 310.69mph at 13,123ft and a climb rate of 9,842ft within 3.5 minutes. This last specification would require an oxygen system for the pilot. The range for both land and carrier operations were common. Range and endurance were vital. Range was 1161 miles but with an external drop-tank, this could be extended to 1932 miles. Endurance was about 1.2 to1.5 hours at 9842ft. The drop-tank extended this endurance to 2 hours. As pilots gained more experience, they could extend this time to between six to eight hours flying time. This extended time was valuable during the invasion of the Philippines.

The ordnance specifications were established as a pair of 7.7mm machine guns and two 20-mm Type 99 cannons firing ball, incendiary or HE shells at 450rpm. There were to be two thirty-round drum magazines. The radio was a type 96 Ku for communications between formations and a Type 1 Radio direction-finding to locate their carrier.

The final weight of the first prototype was 3,570.5lbs.

[oldpop2000]

One fact that should always be remembered. A fighter plane was a gun platform. It didn’t matter how good its performance was, because without sound armament, the plane was of little use. The Model 21, which was the carrier version, had rifle-caliber mg’s with a high rate of fire about 1200 RPM. But the round weighed about .5 ounces. The .50 caliber in US aircraft weighed about 1.76 ounces. This is almost three times heavier. Now, The 20mm gun that the Japanese used weighed about 4.5 ounces and had an explosive charge. However, the 20mm had a low rate of fire and its muzzle velocity was poor. The Japanese reduced the length of barrels on the 20mm to save drag, this made the situation worse. It was easier to hit a target with the 7.7mm guns but against our armored aircraft and self-sealing tanks, the guns did prove to be ineffective unless the pilot was experienced. Over time, many of those experienced pilot were lost and were never returned to the bases to train other pilots so their experience was lost. The IJN did develop other fighters with better armament, but throughout the war, the Zero suffered from the deficencies of armament and the lack of strength in its structures.

[oldpop2000]

Let’s define what A6M designation meant.

A= Carrier based

6=sixth Navy fighter sequence

M=Mitsubishi

1= First version of the prototype 12. The A6M2 was the 2nd version of the Prototype 12.

[oldpop2000]

Here is the secret document of 1938 that generated the request for the Japanese Zero. (If you weren't bored before, you will be now)

12th Air Corps Secret Document No. 169 of 1938

1. Manoeuvrability of fighter planes is paramount.
2. Proof of results of air raids conducted over Hangzhou & Nanchang.
3. Number of Chinese planes approximately equalled the number of Japanese machines involved.
4. Comparative performance of machines about the same.
5. Chinese pilots lacked skill, manoeuvrability and were of low morale.
6. Chinese pilot skill equalled the Japanese but victory attained by individual manoeuvrability of Japanese pilots.
7. Exceptional pilots involved in prolonged dogfights.

8. Japanese planes lost due to fuel exhaustion.

9. When outnumbered by Chinese planes Japanese pilots achieved victory by use of manoeuvrability.

10. Victories would appear to lie with fighters with most manoeuvrability.
11. Folly to disregard this element.
12. Planes required a sharp turning radius with close agility.
13. Next characteristic long range.
14. Physical time endurance on pilots, questionable fatigue factor.
15. Future aerial engagements up to 32,808 feet altitude.
16. Fighter escort missions in summer over Hankou and Nanchang indicate one-and-a-half-hour flight each way to and from target.
17. Combat altitude anticipated to heights of 22,966 feet.
18. Fighter plane escorts not always possible on long-range bombing mission.
19. 12th Air Corps suggested modified attack-bombers heavily armed.
20. Each escort attack-bomber with a ten-man crew.
21. Each escort attack-bomber will require increase in speed.
22. Faster interceptor speed required.
23. Fighter planes with above characteristics an engineering impossibility.

24. Suggest two distinct fighter plane types:

 Carrier fighters

1. Prime flight characteristics must be manoeuvrability. Japanese fighters versus Russian-built I16B Rata (developed from American Boeing P26) in China. Japanese fighters Chinese I16 B 5 min 54 sec to 16,700 ft 6 min 30 sec to 16,400 ft 240 mph max      speed 279 mph max speed
2. Time duration for carrier defence estimated at 1½ hours to 2 hours + 20 minutes combat + 1½ hours return to aircraft carrier. Total 3 hours 20 minutes to 3 hours 50 minutes. a. Long hours represent pilot fatigue and reduced efficiency. b. Unfortunately flights limited by inefficient, primitive navigational equipment.
3. Jettisonable fuel tanks a necessity to equal half capacity of the main tanks.
4. Total cruising endurance equal to three and a half to four hours with jettisonable tanks.
5. The maximum level speed may be 12 mph lower than enemy.

6. The combat heights achieved during the Sino-Japanese Incident ranged from 6,562 feet to 22,966 feet. New fighter planes must operate above this height using two-speed or two-stage superchargers.

Land-based fighters

1. Interceptor fighter type required for search sweeps.
2. Maximum speed a primary characteristic to exceed 46 mph, the maximum speed of the enemy bombers.
3. Plane to maintain adequate stability during diving. 4. Range secondary to speed and manoeuvrability.
5. Combat altitude must exceed 32,808 feet.

6. The Chinese bombers dropped bombs from 22,966 feet up as high at 26,247 feet. Future bombing altitude will exceed 32,808 feet.

 Armament

1. The bomber armament will increase as the speed.

2. The 7.7 mm machine-gun was considered suitable for defending the bombers up to 656 feet range.
3. Future weapons will require accuracy up to 1,640 feet range.
4. An increase in the initial muzzle velocity will be required.
5. With incendiary bullets enemy may be destroyed up to 656 feet.
6. Hitherto the only way to destroy a bomber was to shoot the pilot or strike fuel tanks

7. Effective range of incendiary bullets will increase using 10 mm or 13 mm weapons.

Special equipment requirements
1. A two-way radio telephone will be required.
2. Pilot’s oxygen apparatus.
3. Electrically heated pilot’s suit.
4. Bomb racks so that fighter may be used for ground strafing.

5. A radio direction-finding and homing apparatus must be installed.

However, no provision appears to have been recommended against enemy fire power, i.e. armour plating or self-sealing fuel tanks



Edwards, Peter J.. The Rise and Fall of the Japanese Imperial Naval Air Service (Kindle Locations 2630-2648). Pen & Sword Books. Kindle Edition.

[oldpop2000]

Here are the exact specifications given to Mitsubishi from "Eagles of Mitsubishi" by Jiro Horikoshi. He was the chief designer of the aircraft.

Zero Specs.pdf (68.92 KB)

Note: This aircraft's requirements were both interceptor and escort type fighters. This is a difficult set of requirements to satisfy for any designer. The rest of the world was developing and installing self-sealing fuel tanks, armor and other advancements to protect the pilots. Although the Japanese industries had the technology, the pilots refused. This cost them experienced pilots and the air war in the Pacific.

[oldpop2000]

I wanted to pass along a story about the Japanese Zero-sen and the SBD dive bomber. The SBD is important in our family as my dad on occasion had to fly in the back seat as a gunner so I am familiar with the plane and have seen one. Here is the story.

On August 7,1942 a Japanese ace named Saburo Sakai was over the Sealark Channel in the Solomon Islands. His group of Zero's were to attack the US landing at Gavutu, Tanambogo, Tulagi and Guadalcanal. Over Tulagi, he spotted a group of eight US aircraft beneath him at 7800 ft. He made the assumption that they were F4F Wildcats..... wrong assumption. They were SBD Dauntless dive bombers each with two .30 cal Browning machine guns facing aft. That's sixteen guns facing aft.

He closed in on the SBD's and at a range of 100 yards now realized his mistake; almost a fatal mistake.

The US gunners opened up and his cockpit exploded, canopy tore and the plane went down vertically. Fragments of the bullets hit Sakae in the chest, left leg, elbow and face.

He did survive and eventually was able to fly again. He was one of the best Japanese fighter pilots of the war. The dive bombers expended over 1000 rnds of ammunition in the fight.

The worst thing an unarmored, no self-sealing tank plane could do, is attack an SBD dive bomber flying in formation. They eventually learned to leave the formation alone, and attack after the planes had performed their dives and were heading to the rendezvous point.

My father confirmed this about the SBD's many years ago before he passed away and I've read about it in many books.

Just to refresh your memory. There were two squadrons of  18 dive bombers on every carrier. A VB squadron-bombing  and a VS- squadron-scouting. That's 18 dive bombers  with two guns per plane so that's about 36 x.30 cal. machine guns.

[oldpop2000]

The next version of the A6M Zero was the A6M3 Model 32. Code named the Hamp because Naval Intel thought it was a totally different aircraft. This name was officially dropped when they realized it was just an advanced model.

It started in 1941 when Nakajima introduced the Sakae 21 engine. This engine used a two-speed supercharger for better altitude performance and increased power too 1130 hp. The prototype flew on 15 July 1941

I've copied and pasted a piece from Wikipedia which does a good job of explaining the aircraft. It's easier for me.

"The new Sakae was slightly heavier and somewhat longer due to the larger supercharger, which moved the center of gravity too far forward on the existing airframe. To correct for this, the engine mountings were cut back by 185 mm (7.3 in) to move the engine toward the cockpit. This had the side effect of reducing the size of the main fuselage fuel tank (located between the engine and the cockpit) from 518 L (137 US gal) to 470 L (120 US gal). The cowling was redesigned to enlarge the cowl flaps, revise the oil cooler air intake, and move the carburetor air intake to the upper half of the cowling.

The wings were redesigned to reduce span, eliminate the folding tips, and square off the wingtips. The inboard edge of the aileron was moved outboard by one rib, and the wing fuel tanks were enlarged accordingly to 420 L (110 US gal). The two 20 mm wing cannon were upgraded from the Type 99 Mark l to the Mark II, which required a bulge in the sheet metal of the wing below each cannon. The wings also included larger ammunition boxes and thus allowing 100 rounds per cannon.

The Sakae 21 engine and other changes increased maximum speed by only 11 km/h (6.8 mph) compared to the Model 21, but sacrificed nearly 1,000 km (620 mi) of range. Nevertheless, the navy accepted the type and it entered production in April 1942.

The shorter wingspan led to better roll, and the reduced drag allowed the diving speed to be increased to 670 km/h (420 mph). On the downside, turning and range, which were the strengths of the Model 21, suffered due to smaller ailerons, decreased lift and greater fuel consumption. The shorter range proved a significant limitation during the Solomons Campaign, during which Zeros based at Rabaul had to travel nearly to their maximum range to reach Guadalcanal and return. Consequently, the Model 32 was unsuited to that campaign and was used mainly for shorter range offensive missions and interception. This variant was flown by only a small number of units, and only 343 were built."

On May 31 1942 in Japan, a mixed fighter and dive bomber group for formed with 16 D3A dive bombers and 16 A6M3 Model 32 fighters. The were ferried to Rabaul and arrived about 6 August with the 16 D3D dive bombers and 15 Model 32 Fighters. An additional 20 Zero's were deliver on 29 July to be used by the group.

The timing was interesting as Operation Watchtower, the US Marine landings on Guadalcanal began. However, the Model 32 had a reduced range and could not reach Guadalcanal and get back to Rabaul. Eventually, the Model 32' s were moved to support operations around New Guinea. One of the squadron's was provided with Model 21's to support air raids on Guadalcanal.

[oldpop2000]

The following screen shot is the details of the different versions of the Zeke fighter.

In the summer of 1943 the most prolific version of the Zeke appeared. It was the A6M5 Model 52. The wings were shorter and it had the rounded tips. Ailerons were lengthened out to the tips and flaps were elongated. Wings were thickened to improve diving qualities upto 410  mph  diving speed. Max speed increased to 351 mph. ranges was about 1194 miles with two 12-gallon wing tanks. It had two 20mm cannons and two 7.7mm machine guns. It was a better plane, and pilots now had some armor protection at the rear of his seat, 2 inch. thick of armored glass to protect his head. A new fuel tank behind of the pilot was inserted and it was self-sealing.