Koko's carrier-based aircrafts of WWII:
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Author:  BB1987 [ October 26th, 2020, 9:11 pm ]
Post subject:  Koko's carrier-based aircrafts of WWII:

Deprived of aircraft carrier tonnage allowances by treaty restrictions Koko no Kaigun air arm consisted only (anachronistically) of land-based units and shipborne reconnaissance seaplanes up to the mid-30s when the government decided to join Japan in its denunciation of naval treaties. The carrier-based aircraft division was officially established in 1937 as the country started its ambitious aircraft carrier building plan. Manufacturing of aircrafts followed suit in a mix of Japanese license-build and modifications that coupled with a few suprisingly capable own designs almost took Koko's carrier force from zero to hero in less than a decade before its unavoidable destruction at the hands of the enormous US industrial might and war effort.

Dedicated trainers/Reconnaissance/Other:

Author:  BB1987 [ October 26th, 2020, 9:11 pm ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:


-Mitsubishi A5M (Claude)
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Koko recieved a few units for evaluation in 1937, then started production locally in 1938 for what would become its first carrier-based fighter aircraft. By the time production wrapped up in January 1942 a total of 493 A5Ms had been built by four different Kokoan aircraft manufacturers (Enomoto, Ikehara, Okajima and Tokuda). Operationally the fighter was effectively embarked only on the two light carriers Ahodori and Fukuro and by the sart of the war in December 1941 all had been replaced by the A6M on frontline duties. The A5M then served in limited fashion on the escort carriers and land-based units until late 1943. 88 machines were converted into trainers by adding a second cockpit for the instructor pilot and operated in this new role until the end of the war.

-Mitsubishi A6M Reisen (Zeke/Zero)
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With local production starting in 1940, the renowned Rei-Sen fighter entered service with Koko no Kaigun in March 1941, and by the time conflict erupted in the Pacific some 130 were in service. The A6M2b model formed the mainstay of Koko's frontline carrier-fighters for the first year of the war before progressively being moved to the escort carriers, land-based and second-line units. When production ended in early 1943, 796 machines had been built.
The A6M3 featured a more powerful engine and reduced wingspan with squared wingtips among other modifications, which increased top speed at the expense of range. It debuted in July 1942 just after the Battle off Midway, replacing the A6M2 as Koko's main carrier-based fighter until the introduction of the A7T a year later. Kokoan factories assembled 726 airframes before production ended in early 1944. Many surviving planes of this two earlier model planes were later upgraded with the addition of armor fo the pilot and increased armament (two 13mm machine guns replacing the fuselage mounted 7.7mm pieces) that, while impacting speed and on a lesser extent maneuverability and range, gave them slighly more durability and firepower to face US aircrafts, although a fight against a Corsair was usually hopeless anyway.
Despite born outdated, the A6M5 model was nevertheless produced in large numbers by Kokoan factories, both in its -a and -b models, featuring upgraded armament compared to the baseline. Never seeing frontline service and being only sporadically embarked on escort carriers the A6M5 joined A6M2s and 3s on land-based units and acted as a sort of backup fighter when and if needed. 1.617 were built between 1943 and 1946. Later into the conflict many were given extra armor for pilot protection and three 13mm machine guns in place of the whimpy 7.7mm pieces, giving them the similar offensive capabilities of an A6Mc.
In Addition to the fighter models, Koko also manufactured the two-seat A6M2-K to augment and replace the A5M4-K as the Navy's advanced trainer. 372 were assembled beginning in 1943, with production lasting until the end of the war.
Overall, Koko built a total of 3.139 Reisens between 1940 and 1946

-Tokuda A7T Kazan (Harp)
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Design for a domestic carrier-borne fighter started in late 1940, roughly at the same time the IJN had asked Mitsubishi for a successor for the A6M. Tokuda, the most experienced Kokoan aircraft manufacturer, was given the task by Koko no Kaigun naval staff, who wanted an home-grown design as well just in case delays happened. This proved to be a wise move as developement of the A7M kept stalling until mid 1942. Engine choice befell on the new Nakajima Homare, which promised as much as 1.900 hp of power. The result was a low-wing monoplane that slightly resembled a longer, larger, more streamlined A6M (the cokpit design was mostly unchanged) with folding wings that promised a 650km/h top speed. The A7T, also given the designation name Kazan (Volcano), first flew in august 1942, and featured a still respectable (for the time) armament of two 20mm wing-mounted cannons and two fuselage-mounted 7.7 machine guns. Soon during trials the Homare11 engine proved to have output and reliability problems that effectively limited it to 1.650hp, which led to a reduction in top speed to around 600 km/h at best. Despite the aircraft did not exhibit the same top-level maneuverability of an A6M it was still an extremely agile fighter and was some 60km/h faster than the most recent Reisen models, all while also featuring self-sealing fuel tanks and more extensive pilot protection. The A7T1a was thus approved into production and finally made its carrier debut in june 1943. Its frontline service was short hower, as the improved A7T2 reached service less than 4 months later. The aircraft still found its use in land based units after that. A total of 738 were built between mid 1942 and early 1944.
A new model based on the baseline airframe was developed by Kokoan maufacturer Ikehara specifically for escort carriers operations and named A7T1b. It featured numerous small modifications which included the removal of the drop tank attach points in lieu of a rack capable of fitting up to a single 250kg bomb. This reduced range by over 400km, but such drawback was deemed acceptable given the second-line duties the aircraft was expected to serve, and the lighter aircraft was actually 10km/h faster than an -a model. 1.032 were maufactured in Koko between late 1943 and early 1946. Further 820 airframes were asembled in Japan under license.
While underpowered compared to what was initially promised, the baseline model of the Kazan fighter was perfectly suited suited to act as an advanced high-performance training aircraft. Fitted with a second cokpit for the instructor pilot, the resulting A7T1-K was produced in 277 units between 1944 and 1946.
As soon as the first issues with the Homare11 emerged a new model of the A7T was quickly developed by fitting the more powerful and refined Homare12 which, while still short of the promised output, manged to provide 1.825hp of power. This was enough to raise the top speed close to 630km/h, and the aircraft now outperformed the A6M in anything but rate of climb at low altitudes and turning ratio at low speed. Armament was also increased: the fuselage-mounted 7.7mm machine guns were removed and replaced by two 13mm wing-mounted pieces fitted outboard of the existing 20mm cannons. This had also the advantage of increasing forward visibility for the pilot. The A7T2 entered service in late September 1943 and immediately became the primary carrier-based fighter for Koko no Kaigun, distinguishing itself as a realiable, extremely capable and well respected warplane for the rest of the war, a decent match for an F6F hellcat even when in late 1944/1945 it started to suffer significant attrition against the growing US air-power might. A total of 6.611 A7T2s were produced in Koko from late 1942 to early 1946, with another 1.864 license-built in Japan from 1943-on.
A new Kazan model flew in September 1944 and boosted the new Homare 21 engine capable of 2.000hp that finally raised the top speed to 645km/h, close to the originally envisioned numbers. The A7T3 saw a further increase in firepower, being armed with four wing-mounted 20mm cannons. Entering service in January 1945 it was the primary fighter on all light carriers and some of the larger fleet carriers, where it shared service with the A7M. Under the right circumstances, it was a troublesome opponent even for a Corsair. 2.770 were built domestically in only 19 months of production. Japan also manufatured another 835 under license.
Last developement of the family, the A7T4 model flew in August 1945. It was developed from the A7T2 to serve as a fighter/bomber on escort carriers. A strengthened airframe and tail allowed to carry up to a 500kg bomb, and two drop tanks fitted below the wings increased range to almost 2.100km. A dorsal fin-strake and modified wingtips increased stability, all for a slight drop in top speed to 610km/h. Koko built some 282 A7T4s late into the war.
Overall, Koko built a total of 11.710 Kazans between 1942 and 1946, A further 3.519 were assembled and operated by Japan.

-Mitsubishi A7M Reppu (Sam)
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Long delayed successor of the Zero, it first entered service with Koko no Kaigun in early 1945. Boosting a similar top speed but increased maneuverability and armament compared to an A7T2, it started replacing the latter on the larger fleet carriers thorough the year. 1.324 units were maufactured under license in Koko during the last two years of the war.
Developement of a naval version of the A7M3 was delegated to Tokuda in order to allow Mitsubishi designers some respite and happened pretty much in parallel. Fitting the newly developed Ha-44-11 engine under the hood, capable of 2.400hp, the A7M3c first flew in September 1945 and Boosted an impressive top speed of nearly 690km/h. Its high speed, maneuverability, durability and heavy armament of six 20mm wing-mounted cannons promised it to be quite a formidable fighter. Despite being immediately approved into production the plane never saw carrier-based service given Koko's deteriorating wartime conditions that culminated with the national uprisings in november of the same year. 184 were manufactured domestically but less of a third of them ever saw active service despite proving themselves quite well in combat. Japan attempted to start production in early 1946, but only 2 airframes were completed before US bombings destroyed tooling and blueprints.

Author:  BB1987 [ October 28th, 2020, 10:46 am ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:

Dive Bombers:

-Aichi D1A2 (Susie)
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Just like for the A5M, Koko turned to Japan for its first carrier-based dive-bomber as well. After evaluation of the aircraft in 1937 prodution started in 1938 at Okajima and 154 machines were maufactured until the line closed in 1940. They saw limited carrier service, as they had already been replaced by the D3A by December 1941, and after a brief land-based and training service all were definitely retired by the end of 1942.

-Aichi D3A1 Kanbaku (Val)
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Production of the Kokoan-licensed D3A started at Okajima by fall 1940, with the first units entering service in early 1941. 304 were built by 1942 when production ended. It enjoyed a short but prolific career before being replaced by the D4O on frontline service. Switched to escort carriers, land-based units and finally into training the type was completely retired by late 1944.

-Enomoto D4E Kori (Zither)
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Kokoan manufacturer Enomoto entered the 1938 bid for a successor to the D3A together with Okajima and Japan's Yokosuka. The resulting D4E Kori (ice), a low wing rather elegant monoplane (especially if compared to a D3A), first flew in February 1941 just a few months after the D4Y. It was armed with three 7.7mm machine guns, two wing-mounted and one retractable aft, and had an internal bay capable of carrying up to a single 500kg bomb. However, the plane immediately proved to be underpowered, with a top speed of just 420km/h, offering no performance advantage over the unit it was supposed to replace. Its range was lacking as well. More than anything else, its massive speed deficit over both D4Y and D4O let to the project cancellation after only the prototype and 7 pre-production aircrafts had been completed.
For the massive failure it was, the D4E certainly benefitted from its only real virtue: it was very forgiving to fly and exibithed excellent stability. Soon after the start of the Pacific War the type was resurrected into production as a training aircraft and quickly became Koko's dedicated dive-bomber trainer, remaining in production until the end of the war with 629 units built.

-Okajima D4O Ame (Lyre)
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The other Kokoan proposal for a D3A replacement, the D4O Ame (rain) first flew in July 1941, well after either the D4Y and D4E. However, by that time the former was being plagued by flutter issues and the latter had failed to deliver on so many aspects it was basically a dead duck. In light of this Okajima continued its developement, presenting a rather bulky but impressively performing dive-bomber. Powered by a Mitsubishi Kasei11 engine producing 1.530hp, (a powerplant seen more often on flying boats like the Kawanishi H8K or bombers like the mitsubishi G4N) it was able to carry up to a single 800kg bomb in an internal bay and, despite being less agile then a D4Y, reach speeds in excess of 580km/h without its payload, enough to outrun any carrier-based fighter in service at the time. Its armament was also relatively on the heavy side, with 13mm wing-mounted machine guns and a single 7.9mm retractable mount in the back of the canopy. Impressed by the bomber perfomance the naval staff ordered it into production, and the type began replacing the D3A as Koko no Kaigun carrier-based dive-bomber in May 1942. Later production aircrafts also included self-sealing fuel tanks and armor protection from the crew. This led to a reduction in speed, but despite that the D4O1 remained among the fastest dive-bombers of WWII, on par with a D4Y2 or D4Y3. Between 1941 and 1946 a total of 2.119 airframes were manufactured.
An upgraded model, the D4O2, first flew in February 1945 and was in service by June, just in time for the Battle of the Philippine sea where it proved its worth against US carriers thanks to the maintained 800kg bomb payload. Compared to its predecessor it mounted a more powerful Kaisei21 capable of 1.850hp, which pushed again the aircraft to notable high speeds. The prototype almost reached 620km/h during trials. Even when loaded the Ame was the fastest dive-bomber of the war. Such feat was even more impressive considering that the fuel capacity had been actually increased to extend the operational range, and the armament had been beefed up with 20mm cannons replacing the wing-mounted 13mm machine guns. Some early builds retained the aft-facing 7.9mm machine gun, but this was soon replaced with a 13mm piece. A total of 710 D4O2s were built by Koko before the end of the war. Japan also chose to build this latest variant as it offered a perfomance and range advantage even over the latest D4Y variants, but only 84 planes were assembled before its surrender.

-Enomoto D5E Yogan (Flute)
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After the failure of the D4E Enomoto attempted to provide a potential successor for either the D4Y and D4O, starting developement as soon as the Pacific War started. Result was a rather conventional looking low-wing monoplane with a rather large wing surface area, similar bombload capacity of a D4O and significantly longer range (almost 200km more) powered by a 1.300hp Mitsubishi Kinsei54 engine. It was armed with two 13mm wing-mounted machine guns and a single 7.9mm retractable mount in the back of the canopy. The D5E Yogan (lava) prototype flew in May 1943 but soon proved to be underpowered as well, failing to reach 500km/h, Worse, this time stability was not optimal and further developement of this version was canceled after just one prototype and five pre-production aircrafts had been built.
To solve the issues, the airframe was lenghtened for improved stability and a more powerful 1.560hp Kinsei62 engine was fitted. This time top speed was 560km/h, almost on par with a D4O or D4Y. Redesigned and expanded fuel tanks even increased range by another 100km. Armament was modified to just two 20mm wing-mounted cannons. The prototype succesfully flew in July 1944 but then more problems came up, with the bomb rack release mechanism often malfunctioning, the fuel ignition being unreliable and the airframe needing further strengthening. The type was approved for construction in December after all the issued were solved and finally entered service in May 1945. Just a month later the D4O2 entered service as well, and the D5E2 found itself once again outperformed in every aspect but range. The type saw some action in small numbers at the Battle of the Philippine sea where it had conflicting fortunes. It was capable of absorbing a good amount of enemy fire, but at the same time its large size and slighlt cumbersome maneuverability made it a juicy target for American pilots. By October of the same year it had already been removed from frontline service and assigned to land-based units. Some planes also ended up acting as trainers. A total of 164 were manufactured.
A last-ditch effort by Enomoto to keep the D5E alive was to fit a 1.825hp Homare12 engine under the hood and switch to a four-bladed propeller. With no other significant modifications made the resulting plane was given the D5E3 denomination and flew as a prototype on October 1945 reaching the 600km/h mark. The plane now offered similar performance, range, payload and defensive armament compared to the D4O2, while having a slight advantage in terms of stability, but objectively lacked any sigificant advantage over it. The start of Koko uprisings in November 1945 deprived the D5E from the chance of even be evaluated by the Navy. Only the prototype and four pre-production aircrafts were built.

Author:  eswube [ October 29th, 2020, 8:33 pm ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:

Looking great. :)

Author:  Garlicdesign [ October 31st, 2020, 10:31 am ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:

Hi BB!

How could I overlook this for so long? These are fantastic and totally believable. Production figures initially struck me as rather high, but then the war lasts a year longer in the Kokoverse, so they seem adequate.


Author:  Hood [ November 1st, 2020, 11:33 am ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:

Some very nice designs here, certainly they look very plausible.

Author:  BB1987 [ November 4th, 2020, 9:42 pm ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:

Garlicdesign wrote: *
How could I overlook this for so long?
Would not call just three days "overlook for so long" :P. Anyway, I'd like to thank you and Eswube to have me think a bit more about Kokoan WWII domestic planes or this little thread would have probably not existed at all.
Garlicdesign wrote: *
Production figures initially struck me as rather high, but then the war lasts a year longer in the Kokoverse, so they seem adequate.
It is kind of suprising how a single year of wartime production can change the tally. If we subtract that, figures are not too far from historical Japanese WWII production (10.000+ A6Ms, 2.000+ D4Ys, 1.200+ B6Ns... etc).

Author:  BB1987 [ November 4th, 2020, 9:50 pm ]
Post subject:  Re: Koko's carrier-based aircrafts of WWII:

Torpedo bombers:

-Yokosuka B4Y (Jean)
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As it had happened with the A5M and D1A, Koko first evaluated some D4Ys provided by Japan, then started production in 1938, manufacturing 183 units until January 1941. Like all early stop-gap carrier-based models, the B4Y was quickly relegated to second-line uses, then training, and finally retired by 1943.

-Nakajima B5N Kanko (Kate)
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Production of the B5N2 under license began in December 1939, with the type starting to replace the B4Y as Koko main shipborne torpedo bomber already by the second half of 1940. Given the delays suffered by the B6N and B7A, the B5N had to soldier on as Koko no Kaigun frontline torpedo bomber until the first half of 1944 despite being completely obsolete, suffering significant attrition in the process. Even so, the type still got used in small numbers as a trainer or land-based unit until the end of the war. Overall, Koko produced a total of 1.238 B5Ns between 1939 and 1944, more than Japan itself.

-Nakajima B6N Tenzan (Jill)
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Delays and teething problems with the Japanese developement of the B6N meant that Kokoan production of the type began only in August 1943 for its introduction into service in December of the same year. After extensive usage and fluctuating fortunes through 1944, most were replaced in carrier-based service during the first half of 1945. The B6N2 ended its wartime career as a land-based unit like many other aicrafts. 810 airframes were manufactured between mid 1943 and late 1945.

-Aichi B7A Ryusei (Grace)
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Multiple issues that led to mandatory airframe modifications also caused a delay to the torpedo/dive-bomber model that what was intended to be a replacement for both the B6N and D4Y. Production in Koko only started by fall 1944 and the aircraft first entered service in small numbers in January 1945 as production did not ramp-up fast enough to equip all the fleet carriers. With the ultimate destruction of the Kokoan carrier force in October 1945 all surviving B7A2s were moved to land-based units. 203 were built.

-Tokuda B8T Fubuki (Horn)
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Confident in the short-term avaliability of not one, but two new models being developed in Japan, Koko chose not to start developing its own carrierborne torbedo bomber in order to focus on different aircraft designs. By 1942 it became clear this had been a significant error of judgement, as both the B6N and B7A were piling-up a massive amount of delays to their planned entry into service. Since the D4O was considered capable enough to keep serving as a frontline dive-bomber Tokuda designed the new airplane as a torpedo-bomber only, and not as a dual-role aircraft like the B7A, to speed up its developement. Given the B8T Fubuki (snowstorm) designation the aircraft grew around its planned 2.200hp Ha-43-01 engine (the same that equipped the A7M) to become a low-wing monoplane reminiscent of the B7A in its appearance (the aft section of the fuselage and part of the tail were almost identical). Armed with two 20mm wing mounted cannons and one 13mm machine gun in a retractable mount in the back of the canopy. The B8T1 first flew in September 1944, trials revealed it was capable of exceeding 630km/h (without payload) and had a range comparable to that of the B7A, although it was not as much as maneuverable. It entered service in March 1945, augmenting the airwings of most Kokoan carriers for the rest of the war. 674 were built between 1944 and 1946.

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