Part of the first wave of great World War II fighters, the first flight of Mitsubishi’s famous Zero came on April 1, 1939.

Let’s take a look at an important type that was so secret it was almost entirely unnoticed at first.

Starting in 1937 the Imperial Japanese Navy issued an order for a new fighter to replace the Mitsubishi A5M, which was just entering service. They sent their “12-shi” list of requirements to both Mitsubishi and Nakajima. The requirements were pretty ambitious for the time, They wanted a top speed over 310 mph, climb to 10000 feet in less than 10 minutes, an endurance of 6-8 hours with drop tanks, and armament of 2 x 20 mm cannon.
Further, the new type had to equal or exceed the maneuverability of the A5M and be the same size (to fit on aircraft carrier elevators).

The wise engineers at Nakajima concluded the requirements were unattainable and withdrew from the bid. Mitsubishi’s chief engineer, Jiro Horikoshi, thought it was doable but not easily. It would require extraordinary weight control and a new top secret aluminum alloy called “extra-super duraluminum (ESD)”. This was a remarkable new alloy, with superior weight to strength numbers; it was however prone to rapid corrosion and fatigue (which has some impact on why so few Zeros are still airworthy and is a constant headache for their owners).
The rest of the formula behind the new A6M is well enough known, very light construction and painstaking attention to a streamlined form.
Armor for the pilot and self sealing fuel tanks were just becoming standard in most of the world but Horikoshi’s fighter was light in every sense, which not only meant such features were not used but that it would require more than a “simple” fix when it was accepted that they were needed.
The pilot’s canopy was a revolutionary feature that often gets overlooked. Obviously not a true “bubble”, but the seat was high and the canopy allowed a 360 degree view. As revolutionary as the Hawker Typhoon’s bubble is often considered, the Zero was practically there first.
The wide undercarriage and low speed wing were all about making the Zero a superb carrier aircraft. That wing design also made the type supremely maneuverable at low speeds.

As so often happens, several of the prototype’s features were changed before series production. The two bladed propeller was found to cause concerning vibrations and was replaced with a three bladed unit within a few weeks (I suspect the original propeller also failed to capitalize on the engine’s full output). The second prototype was also delivered with a two bladed propeller, but also not for long. The engine was initially Mitsubishi’s own Zuisei; it was rated at 850 hp, but it struggled to perform as advertised (perhaps due to a supercharger that was also problematic). The Navy insisted on a switch to Nakajima’s more reliable Sakae engine, this technically defines the difference between the A6M1 and production model A6M2 aircraft.
Both prototypes came with an “anti-spin” ventral stabilizer in the place where the tail hook would eventually be mounted. I find this an amusing story, Horikoshi was apparently quite annoyed that the company had added this thing that he felt did nothing, and ruined the fine lines of his airplane. I believe we only know about this because the designer went off on the subject in a post-War book he wrote on the development of the Zero; but no photos or engineering drawings of the fin survive (as far as I know). When Hasegawa kitted the A6M1 (2000 or 2010? It was to celebrate one of the Zero’s anniversaries) they included the stabilizer, and helpfully had different profiles for the first and second prototype. So how do they know? Maybe they found an eyewitness or interview I know nothing about? I think I’ll have to call this feature speculative.
Also note the model shows armament. Granted, for the 20 mm cannon that just means some holes in the wings; but the 7.7 mm machine guns are visible in the cockpit and the barrels exit the fuselage just before the cowling. Now I do know that eventually this plane WAS armed. The first prototype was turned over to the Navy in September 1939 and was doing gunnery tests in November. But it seems odd to me if it made its first test flights armed? And the two bladed propeller was only used for about six weeks. So let’s say for our purposes here it was armed, or at least had realistic dummies installed for weight and balance reasons! That’s my story and I’m sticking to it…

Its also worth mentioning the new Type 99 20 mm cannon used on the A6M. Through the 1930s most of the World was still using light caliber machine guns in their fighters, usually two light machine guns just like at the end of World War I. In the mid-1930s it was becoming apparent to many that with faster speeds and more rugged aircraft that it might not be adequate for a future conflict. A Japanese naval observer in France saw the new 20 mm cannon by Swiss manufacturer Oerlikon and pushed for its adoption. By 1937 the Navy had decided on licensed manufacture of that weapon. The Type 99 was developed for the Japanese by Oerlikon engineers working in Japan. It was specifically light in keeping with the whole theme of the Zero. Later derivatives were heavier and improved muzzle velocity and rate of fire. In December of 1941 the Oerlikon engineers were arrested like most other westerners and spent the remainder of the War incarcerated.

This aircraft represents the first of the two A6M1 prototypes. Chief designer Horikoshi gushed over its beauty. Obviously a bit of a bias; but he was also the chief designer of the A5M (Claude), G4M (Betty), F1M (Pete), A7M (Sam), Ki-51 (Sonia) and many others. As far as I know he only gushed over the Zero. The Mitsubishi plant was located some 30 miles from the nearest airfield, via unpaved roads. So the plane was crated and transported by ox cart, taking a full day. (This situation was never rectified. To the end of the War Mitsubishi’s output was dependent on ox carts and healthy, well fed beasts).
From the first flight on April 1, 1939 the pilot was pleased with the aircraft. There were tweaks and modifications, as there always are, but the basic form remained unchanged for production. After completing basic flight testing, both prototypes were accepted by the Navy for more advanced testing including radios, weapons and other military equipment.

As mentioned earlier, this is the Hasegawa kit. It is an easy build and I left it mostly clean, like its ready to go for that first flight.