Empire of Japan (1942)

Fighter – 621 Built

Intro

The J2M Raiden, Japanese for Thunderbolt, was developed to provide the Japanese Navy with an interceptor for the defense of its bases in China and across the Pacific. While it was designed with many of the most advanced technologies available to Japanese aviation, its development was fraught with technical issues and resource competition with the Navy’s premier fighter, the A6M Zero. After several years in troubled development, it entered service in the last line of defense against the American Army Air Force and Navy, which had taken the war to the skies over Japan itself.

Foundations

Japanese military aviation began early, but ambitiously, with the Navy launching its first naval air attacks from the seaplane carrier Wakamiya against various German targets during the First World War. There was little damage done with these light, and very crude, seaplane bombers, yet it was clear that as the technology matured, aviation would take a key role in any future conflict.

Following the end of the first world war, Japan claimed former German territories across the pacific, and sought greater control over China, then embroiled in a brutal civil conflict. The Washington Naval treaty would affirm the integrity of Chinese territory regardless of the wars, and assure equal economic rights for those wishing to trade in the region, and the Empire of Japan would not contest these principles through the 1920’s. However, its armed forces nonetheless planned and lobbied for ambitious policies that would wrest control of most of Asia from the Chinese, and the Pacific from the Europeans and United States of America. However, as a still nascent industrial power, Japan had much to learn regarding the cutting military technologies that they would need to challenge their many planned opponents.

A longstanding alliance with the United Kingdom had brought rapid advancements in both military and related civil fields. This was only one part of a military partnership that had once challenged Russian ambitions in Asia, and had led them against the Germans in the Great War. By the end of that war, this alliance was wearing thin, with both sides now holding opposing goals across Asia and the Pacific. Yet one final major transfer of technology would catapult Japanese aviation ahead, before military coordination with Britain finally lapsed. Following a request for technological assistance in aviation in 1920, the Sempill mission was organized to bring Japanese expertise in aircraft design and development up to modern standards. While there were clear concerns that this technology might be used to challenge British interests in the future, major economic partnerships and sales with Japan proved a stronger motivation.

The mission arrived at Kasumigaura in 1921, led by former RAF officer Baron Sir Williams Frances-Forbes. Along with a cadre of experts in airplane design, construction, and use, the mission brought a collection of aircraft. Over a hundred planes in total were delivered to Kasumigaura, accounting for modern military aircraft of every type available to the mission planners. To the Japanese military, this technology exchange was as generous as they could have hoped for, and put them on a faster track to self-sufficiency. This massive leap in technical abilities would define Japanese aviation moving forward, giving their industry a firm grasp on modern construction techniques and technologies, but still lacking depth in manufacturing.

While they would continue to be reliant on licensed equipment for the years to follow, they now had a strong technical foundation from which to build on. Just as this assistance ended, so too did the alliance with Britain, which lapsed in 1923. The very same year, the Navy would select the United States as its chief ‘hypothetical enemy’, against which future war plans would be focused.

War Games

The aviation industry was slow growing, beginning with cottage industries that eventually grew into major enterprises, that later made the leap from licensed equipment to their own designs. The largest of these manufacturers were Mitsubishi, Nakajima, and Kawasaki, which provided the nucleus for the rest of the cottage industry based aviation sector. Arguably the largest of these was Mitsubishi Heavy Industries, through its branch, the Mitsubishi Internal Combustion Engine Co. at Kobe. Concurrent with the Sempill mission, the company’s aircraft manufacturing effort was shifted to Nagoya, which would remain the center for Mitsubishi’s aircraft development and production. In the years to come, additional production plants would sprout from the main facilities in Nagoya, with separate air frame and engine departments being founded by 1935.

Given the state of aviation in Japan in the late twenties, the first major war plans against the United States made very little use of aircraft, with the plan being to draw the US fleet into Japanese territorial waters where it could then be devastated in a decisive battle, the outcome of which would decide the fate of untold millions. The rationale and foundation for these plans was to develop superior technologies in key areas, and in all others, the supposed superior qualities of the Japanese soldier would allow them to persevere, confident in the belief that material shortcomings were minor impediments to seizing a victory that was destined. In practice, they initially sought to out-match the enemy in the areas of long range gunnery and torpedo warfare, to claim a decisive edge against an enemy which was beginning to eclipse them. Yet, in time, the need to master the air would come before all else, as it became clear air power could make up for disparities elsewhere.

Battleships defined the plan until the mid 1930’s, with aviation playing a very small role until several crucial technical developments were rolled out. Aircraft at the time had a very limited range of action, had small payloads, and were very fragile. The coming war for the Pacific would be waged against a number of very powerful opponents, and such a battlefield would be vast and feature the most powerful pieces of military equipment in existence, modern warships. It was the development of all-metal, streamlined, monoplanes that proved to be the deciding factor in shifting the idea of the airplane as a defensive weapon and reconnaissance tool, to a deadly offensive weapon. The ability to conduct strikes of greater power, and scout ever larger swaths of ocean continually pushed the boundaries of military planning. The hypothetical decisive battle was taking place further than the originally conceived battlefield in Japanese home waters, and by the late 1930’s, it was judged to take place around the Marianas.

In the Navy’s plans, torpedo and dive bombing aircraft were pursued enthusiastically, with fighters far less so. Seen as a mostly defensive weapon, there was little development in their advancement or tactics between the Sempill mission and the end of the 1920’s. This changed after a pair of RAF officers were invited to present a five month fighter course in 1930, and a larger fighter maintenance and employment course was provided the next year, again with RAF personnel. The naval air combat program would soon grow under Lt. Kobayashi Yoshito, Lt. Genda Minoru, and Lt. Okamura Motoharu at the Yokosuka Naval Air Base. By this time, there were two major issues with the program, the first being the general reluctance for defensive tactics by the Japanese Navy, and the fact that bombers by this time were capable of out-pacing their pursuers. With their relatively crude Nakajima Biplane fighters, there was little that could be done to face and bring down modern bombers. Yet the fighter advocates held out, and waited for new planes, ones that could demonstrate their necessity on carrier flight decks and naval air bases.

Horikoshi and the Zero

By the mid 1930’s, there was a swell of engineers who had been schooled in the advancements brought forth by the Sempill Mission, and a good number who had traveled abroad to see new technologies and techniques in use with the forerunners of aviation. It was this latter group that was the most pessimistic about Japan’s ability to wage war against the US, as they were witness to America’s vast manufacturing potential and technological expertise in all the fields relevant to the war in which their own work would one day contribute. During this time, Japan had invaded Manchuria, and planned for a greater war which could place China in their orbit. Needing to modernize, the Navy sought to push past the old Nakajima N4A, which had become very dated by 1934, and obtain a fighter which could match the performance of the bombers it chased. New high speed fighter requirements were prepared by Lt. Cmdr. Sawai Hideo from the Department of Engineering at the Naval Air Arsenal, and released to the industry.

Horikoshi Jiro had studied at the brand new Department of Aeronautics at the University of Tokyo, which at the time, numbered only 39 people, staff and students. From there he went on to work at the Mitsubishi Internal Combustion Engine Co. at its aircraft department, working first on the basic, yet essential tasks of running performance and strength calculations, and designing various components. In time, he would be selected to study foreign methods of aircraft construction, and would travel to Germany, France, Britain, and the United States to tour factories and study the planes they built. While Japan was clearly still lagging behind the leaders in aeronautics, he knew a quick path to design parity was only a few leaps away.

However, despite his belief Japan could find a way to produce its own cutting edge military aircraft, Jiro remained pessimistic about the Empire’s chances in a war with the United States, having toured the aircraft manufacturing plants in America himself. He would remark in later years, after learning of the attack on Pearl Harbor, that “-The majority of us who had truly understood the awesome industrial strength of the United States never really believed that Japan would win this war. We were convinced that surely our government had in mind some diplomatic measures which would bring the conflict to a halt before that situation became catastrophic for Japan.” Yet well before the dawning of the Pacific War, he continued his work in pushing the boundaries of aeronautics in Japan.

Understanding that the monowing fighter would be the future of its class, with its obvious advantages in drag reduction and strength, he would pursue designs of this type from his first attempt. It would not go well, as there were many technical challenges that had to be overcome, but overcome he would, and his next design would prove phenomenal. For the 1934 Naval requirements for the year 9 carrier fighter, he would submit the Mitsubishi Ka-14, later modified into the A5M fighter. A superlative modern fighter, it impressed the Navy enough to purchase a large number of the aircraft.

The A5M would prove to be the start of an exceptional career for one of the era’s foremost aeronautical engineers, a major leap for the Japanese aero industry, and it gave the Japanese Navy proof that fighters were an essential investment in any future war. It proved a decisive success in China, but as is always the case, a successor needed to be planned for. For the next carrier fighter, the Navy released the planning requirements for the year 12 carrier fighter. They had effectively asked for the impossible, a plane that needed to be able to act as an interceptor, a long range escort, and air superiority fighter. To make a long story short, Horikoshi managed to design a plane which met the requirements, and produced the A6M Type 0 fighter.

In addition to this aircraft, which would become the primary fighter of the Japanese Navy, another design would be requested in October of 1938. A local fighter, a dedicated interceptor to defend Japanese positions in both China and the Pacific from enemy bombers. While a seemingly simple request, it represented a rapid and enormous shift in naval strategy. At the outset of the 1920s, the airplane was little more than a novelty which played a supporting role. Experience in the agonizing war in China showed that bombers could now threaten the Navy’s ports and airfields, such that a specialized aircraft was needed to counter them. Gone was the reluctance that dogged officers like Lt. Genda in pursuing a purely defensive aircraft.

The fact that the Navy was developing a land based fighter at all, while the Army had several designs at its disposal, was a factor of the vicious inter-service politics that defined their relationship. Both vied for supremacy over control of national politics and industrial resources, and so competitive that they denied each other use of the same designs. Concurrent with the Navy interceptor project, the Army was also seeking an aircraft for the same role, in their case the Ki 44 Shoki. Resources spent on these parallel efforts were a major handicap to both the Army and Navy, and would prove catastrophic to the overall Japanese war effort as later events would show.

The Navy’s request for the interceptor called for a maximum speed of 323 kts at an altitude of 6 km, a landing speed no greater than 70 kts, an endurance of 45 minutes, a take off run of 300 m at full load and with no wind, and it had to have the same armament as the A6M fighter, being two 20 mm machine guns, and a pair of 7.7mm guns. It was also the first Japanese fighter required to carry an armored plate behind the seat back to protect the pilot.

It was in many respects the reverse of the Zero, where maneuverability and range were sacrificed to achieve the highest possible rate of climb. However, unlike the Zero, significantly fewer resources would be available for the engineers working on the aircraft. With the Zero being made the premier fighter of the Japanese Navy, a constant stream of improvements would be ordered over the next several years, straining both the development of the Raiden, and other Mitsubishi aircraft, namely the G4M bomber.

A Troublesome Development

The first major design decision came in the form of the choice of engine, with two major contenders. The Aichi Atsuta, a 1200 hp V-12, and the Mitsubishi Kasei 13, a new 14 cylinder radial. The Atsuta was a licensed development of the Daimler Benz DB 601A, and as was the case with most licensed foreign designs, was being sold as it was no longer a cutting edge design in its own country. Nevertheless, the Army would use the licensed engine in their own Ki 61 fighter, developed by Kawasaki as the Ha40. Aichi was within the Naval military industrial sphere, and thus unavailable for Army orders. Despite both engines looking identical and being derived from the same common model, they had few interchangeable components and fittings due to differing Army and Navy requirements, and the different manufacturing practices between the firms. This level of parallel effort was both extremely expensive, and not at all uncommon. For the Raiden design team, the DB 601 derivative presented a light, streamlined engine, but also one with more limited paths for improvement.

The Kasei was still in its teething period, but was substantially more powerful and had better prospects for further development. While the engine’s higher fuel consumption was not problematic given the short range requirements, its size forced some compromises. To reduce drag, the engine was set much further back from the nose of the aircraft, with an extension shaft running through the tapered cowling to the propeller. The space was also shared by the oil cooler, supplied with air from an air flow driven fan. Further aerodynamic streamlining came from setting the canopy in a shallow frame, and the use of an advanced high-speed wing with aerofoils incorporating research in laminar flow. While maneuverability was not a primary concern of the aircraft, it would receive ‘fowler flaps’ which could be deployed via a button on the yoke, enabling the aircraft to make tighter turns in combat, at the cost of speed.

The Raiden’s development was plagued by numerous technical issues from a very early stage. There were issues with the engine, the cooling system proved inadequate given the small inlet for air at the nose, and the canopy proved to be extremely cramped with major restrictions in visibility. Worse, it competed for resources with the Zero, which included the already overworked engineer Horikoshi himself, who was also tasked with designing its successor. While being developed well before the coming war with the United States, the prototype wasn’t ready until February, 1942.

The Raiden first flew on March 20, 1942 at Kasumigaura, revealing a number of major faults. Numerous engine related issues cropped up, most notably trouble with the propeller’s constant speed governor and heavy vibration. Navy pilots who went on to test the aircraft were also extremely frustrated with the curved canopy, which not only restricted the range of view, but also caused optical distortions at certain angles, which were especially pronounced on the landing approach.

However, it flew notably well, featuring high stability and responsive controls. These were not able to overshadow the aircraft’s more visible faults, and inability to meet project goals. It failed to exceed 311 kts at its target altitude, and failed to reach its time to altitude requirements. Beyond the need to increase its overall performance, members of the IJNAF’s Air Arsenal required a redesign of its canopy, and improvements to its constant speed propeller mechanism, which proved to be one of the most troublesome issues in their several weeks of testing.

The canopy was most easily remedied, replaced with a more conventional design with flat windscreen panels. However the engine remained a more vexing problem. Several issues were intertwining to make further development far harder. First was the relatively new Kasei 13 engine itself, with its own teething issues, second was the inadequate oil cooler, and there was the fact that the engine itself was to be replaced with an even newer model to allow the plane to reach its required performance, which brought its own uncertainties. The Kasei Model 23 would prove much more powerful, and a later model would add methanol-water injection, the anti-detonation properties of which allowed the engine to run at higher manifold pressures, allowing it to produce 1800 hp. There were also more minor improvements, such as the introduction of a new oil cooler beneath the nose, the air driven cooling fan was replaced with a mechanically driven one, and the addition of exhaust stacks for each cylinder. Along with the engine came a new four bladed VDM propeller with a re-balanced governor, to address the unreliability of the previous model. There was much confidence in the new engine, which was premature.

Operating the engine at a high output would prove troublesome, with excessive exhaust smoke, and extreme vibration being apparent from the outset. The smoke proved simple enough to address via the fuel injection system, but the vibration would remain with the aircraft through its entire career. It was brought up to Horikoshi that the use of the extension shaft might be the cause, though he adamantly denied this. He was at least partially correct, as the propeller design left much to be desired. In time, the vibration issues were addressed through the use of rubber buffers on the engine mounts, which along with the redesigned propeller governor, reduced vibration to manageable, but still noticeable levels. While Japanese aviation had a number of enviable technologies at its disposal, its propeller designs lagged behind that of the US. Harmonics were thus an issue that limited the performance of all Japanese high performance engines, but were particularly harsh on the J2M.

The aircraft was re-designated J2M2, but prototyping and pre-production continued at an extremely slow pace. To make matters worse, a pair of J2M2 were lost in early testing, just as the aircraft was being prepared for large scale introduction. One was lost on a basic test flight on June 16, 1943. The test pilot, Lt. Hoashi Takumi, lost control of the aircraft and struck a barn after trying to regain control after take off. He died when the aircraft caught fire shortly after the crash. In a non-fatal incident that occurred a month later, test pilot CPO Sasakibara Masao managed to land the J2M2 after encountering major handling issues. This incident offered no explanation for its cause, which was only discovered weeks later. On another test flight, a Mitsubishi test pilot, Shibayama Eisaku, found that the yoke was pulled forward when the landing gear was retracted. Being at a higher altitude than Lt. Takumi was when he started to retract the gear, he was able immediately lower it, and regained control of the aircraft. On some aircraft, it was found that the retracting tail wheel was coming to rest against the elevator controls. The problem was remedied, though only by late 1943.

While technical issues continued to plague the development of the Raiden, the Navy was still conducting tactical and performance tests with the prototypes. In the autumn of 1943, the Navy had several prototypes of the new fighter at its disposal, a number of them the older J2M1. The Yokosuka Air Corps would put these aircraft in mock dogfights against their A6M3 Zeros, finding the J2M1 was at a serious disadvantage when using the typical Navy fighter tactics, which favored horizontal maneuvering over climbing and diving. Its true strength was in energy fighting, with the pilot keeping to a high speed and expending little energy through more aggressive horizontal maneuvers, and outmaneuvering them by attaining a higher energy state. Unfortunately, this point was not stressed in their reports, and pilots stuck to the more traditional tactics that the aircraft was less suited to.

Their attempts in mock interceptions of bombers also proved troublesome, not for any purely performance related reasons, but that the J2M1 fighters they were using were very unreliable. As was the case in earlier tests, the propeller governor failed when the aircraft was put through harsh maneuvers, and in another instance, a throttle had gotten stuck in the forward position. Veteran pilot and Ace, CPO Oh-hara Ryoji, experienced both such failures, and performed multiple unpowered landings in the fighter.

Troubles aside, development of the fighter continued, resulting in a new J2M3 model with a heavier armament of four 20 mm guns, and an improved oil cooler. The weight of the new equipment would again put it behind the performance figures set in place then five years ago, though the heavier armament would prove important in facing the resilient heavy bombers in service with the US. These improvements aside, they were unable to trace the issues of the harsh vibrations from the engine, and proceeded to production regardless, believing the measures in place to be sufficient. After much delay and considerable frustration, the Raiden was moved toward mass production at the end of 1943, at a relatively low figure of some 20 aircraft per month. Only 90 would be built in 1943, with only another 274 the following year, most being the J2M3 Model 21.

Its production was mostly motivated out of desperation. The Navy had at its disposal only one major fighter model at that time, the Zero, which had gone from dated, to obsolete, from mid 1943 to early 1944. It was supposed to have been succeeded by the A7M, which failed to proceed past prototyping. Making matters far worse, in the land based land interceptor role, the Raiden was now years behind schedule, leaving vital forward anchorages to be defended by the aging Zero. The Navy’s alternative to the troubled Raiden was the N1K-J Shiden, though it would not materialize in the numbers needed for many months. Thus the Raiden was to be produced in limited numbers, being the only fighter the Navy was confident could intercept American bombers, especially the newly discovered B-29 which intelligence services had identified well before its debut.

In dealing with this particular threat, there were attempts to fit the Raiden with a high altitude engine. A J2M4 was thus created with a turbo-supercharged Kasei engine, and a J2M5 was built with a three speed supercharger. The turbo-supercharger proved far too unreliable for service, with the three speed supercharger proving to be somewhat more manageable. While both experimental models did have much better high altitude performance, neither were able to be employed, leaving the Navy without a high altitude interceptor.

The Whirlwind

By the start of 1944 the war had been fully reversed against the fortunes of the Japanese. The long, grueling Solomons campaign had drained them of the corps of elite airmen they had carefully cultivated since before the start of the war, and US industry was producing enormous amounts of war materiel. The situation was soon to grow even worse as the United States began to prepare the deployment of one of its newest, and most advanced weapons.

Japanese intelligence services first became aware of the B-29 after reading of the death of a test pilot flying a new Boeing bomber in early 1943. They would soon produce speculative performance capabilities for the new bomber based on what they knew of the known abilities, and likely new improvements, of the US aviation industry. They proved to be reasonably correct in their efforts, and concluded that major raids against Japan could be expected by early summer 1944. The bomber was first deployed to a base in China, at the Chengtu complex, a distant and difficult to reach airfield, which proved to be far from ideal to keep supplied, and offered a limited ability to strike at the Japanese mainland. They first raided the rail lines in Bangkok in June of 1944, as they prepared for a greater offensive. Their first raid over Japan took place on the night of June 15/16, and mirrored the operations of RAF Bomber Command, with pathfinders going ahead of a long, dispersed line of bombers to mark targets. This effort, and the many that would follow would prove unsuccessful, night raids were an exceedingly difficult affair that demanded the highest levels of flying proficiency, and high altitude operations would be complicated by the powerful jet stream, which also reduced the accuracy of daylight raids considerably.

These many issues aside, the B-29 made a considerable impression across Japan. It was an opponent that was advanced as it was elegant, its tendency to catch fire due to the use of a magnesium alloy accessories case, was unknown to those who faced it in combat, or the civilians who endured its presence. Author Kosaka Masataka would note its “beauty and technological perfection” which to his mind symbolized the mark of “higher civilization” achieved by the United States. One of the first Japanese airmen to encounter the new bombers, ace and night fighter pilot 1st Lt. Isamu Kashiide, would be awestruck at the sight of a B-29 that had been coned by searchlight. Remarking, “I was scared! It was known that the B-29 was a huge plane, but when I saw my opponent it was much larger than I had ever expected. There was no question that when compared with the B-17, the B-29 was indeed the ‘Superfortress’!”

These encounters would grow in frequency and lethality as the raids mounted. The Chengtu complex was supplemented by new bases in the Western Pacific, notably the enormous base on Tinian, and the appointment of a new, aggressive commander, General Curtis LeMay. Against them was the dwindling cadre of experienced Japanese airmen, who had relatively few advanced interceptors to call on.

The Raiden In Combat

With the end of its less than ideal development cycle, the Raiden made its service debut with the 381st Air Group, in October of 1943. However, after constant teething issues with the aircraft, and a fatal accident resulting from an unidentified air frame failure, the squadron would have its Raidens exchanged for Zeros before their deployment to the Philippines, and the Dutch East Indies, in March of the following year. In September, after several months in combat, they received some ten J2M3 Raidens while deployed to the Celebes. The combat debut of the new aircraft came with some success, as during an intercept of a large number of American B-24 bombers, one victory was credited to the new fighter. They continued their service there, and found the new aircraft to be a potent combatant, with noted success against American P-47 and P-38 fighters, as unlike the zero, Raiden pilots could escape them at lower altitudes and were still able to comfortably outmaneuver them.

The 381st continued its service through the Battle for the Philippines, defending Japanese positions around Manilla, and later, the oil industries in the region. There were also Raidens in service with other units, notably the 301st Air Group which served in the central Pacific, which struggled, making use of the older and less reliable J2M2, and facing considerable opposition from massed American air power in the region. There were otherwise a handful of other aircraft serving in outlying theaters on a mostly provisional basis, with very little known of their use.

Aluminum Overcast

The American air raids against Japan were to enter their penultimate and most brutal stage in early 1945. Earlier raids were done from high altitude, and did so with the difficulties of having to juggle the difficult basing situation in Chengtu China, and the weather. The weather proved frustrating for lack of access to intelligence gathering in the region, save for the Soviets who refused the use of their services to maintain their neutrality, and whose broadcasts were shrouded by constantly changing codes. However, General Curtis LeMay would employ new tactics allowing him to side-step the issue of the weather, and the Americans had constructed new bases in the Marshall Islands which would allow for the comparatively easy amassing of bombers. LeMay chose low altitude, incendiary saturation bombing, the most blunt, and brutal of the methods available to him. Earlier, smaller scale incendiary raids, including one against the Mitsubishi works at Nagoya had proven successful, though they soon pivoted toward targeting cottage industries in urban areas, and the civilian population. This shift in tactics can occurred rapidly, seen in a single raid on February 25 of 1945, where some 200 B-29’s raided Tokyo which saw fires burn uncontrolled across a large swath of the city.

To make a desperate situation worse, when LeMay’s XXI Bomber Command began raiding Japan in force, they weren’t alone. On February 16th, a major incursion performed by carrier based aircraft swept across the shores of Honshu, launched from Task Force 58, which accounted for 16 fleet carriers, and 116 warships in total. Admiral Mitscher would sortie 1,187 planes; 895 fighters, 201 torpedo bombers, and 91 dive bombers. They would contest control of Japanese airspace, and strike at the targets LeMay had not, mostly factories producing materiel for the Japanese war effort. The next day, he launched another 1,574 sorties before departing southward to engage the Japanese forces on Iwo Jima. In this uneven fighting, he lost only 80 planes to all causes with the Japanese claiming 134 kills. With the subsequent loss of Iwo Jima, came the first encounters with P-51 mustangs, now based from that island. They first came north on April 7th, where they quickly showed themselves to be a dangerous opponent.

The Japanese defensive situation during this time period grew from difficult to dire. The quality of the aircrews had declined even further after the disastrous encounter in the Philippine sea, and the following American invasion of the Philippines itself. There, the Navy had spent its last strength in an attempt to prevent American forces from staging a landing, following a plan which could never have hoped to succeed. The merchant marine had also been decimated, and the heart of the Empire was thus seeing shortages of every kind. There were no offensive means by which the war could be fought, and the enemy was closing in from all sides. Despite a situation which could only resolve itself in a painful defeat, the Japanese armed forces chose to continue the war in the hope for a conditional end to hostilities.

There was little hope for anything approaching a favorable outcome in continuing the war, yet fatalism ruled, and the country marched on. The exuberance of the early victories was gone, the hopeful energy of the early Solomon campaign had faded, and China remained vast and unconquered. In the Autumn of 1944, ace Navy Pilot Lt.jg Sakai Saburo returned to Tokyo, after several years on campaign and the loss of an eye. “The city appeared drab and lifeless. – Most of the stores were closed, their windows empty. The significance was clear. There were no goods to sell, and the owners were away, working in war plants. The few stores that remained open hardly resembled the colorful and well-stocked establishments I once knew. Few goods were on display, and for the most part these were crude substitutes.” It was this city that was to become a battleground in the months to come.

Just as pressing as the approaching American forces, the division between Japan’s air forces, Army and Navy, would prove a critical fault which saw them face this storm almost totally unprepared. Despite the early warning of the B-29 threat, there was no comprehensive plan for the defense of the Japanese mainland from air attack, the strategic outlook of both forces was one defined by delusion and self-sabotage. From the outset, the Army and Navy each had their own jealously guarded industrial complexes, possessed few compatible munitions, and operated aircraft with no common base for components. Army and Navy aircraft of similar design did not even possess a common voltage. They pursued aircraft development and research separately, further dividing the pool of expertise and industrial base, which were dwarfed by their rivals in America. The Navy commissioned some 53 models of aircraft for which there were 112 variants, and the Army 37 models with 52 variants. Making matters worse was the failure to prepare, and expand aircraft production in wartime. The Ministry of Munitions was only finally established in 1943 to better convert Japanese industries for military use. In 1944, its head, Fujihara Ginjiro, found that with the ideal utilization of Japan’s industries, the level of annual aircraft production could have been as much as 53,000, rather than the 8,000 to 10,000 which were being turned out. While the figure is purely theoretical, it nonetheless demonstrates the widely impractical decision making that dominated Imperial Japan’s industrial planning.

Even critical pieces of equipment, such as early warning radar, were developed separately, and hoarded to build separate networks with little collaboration. The Army used its Tachi-6’s and 7’s, and the Navy its ground based Mark I radar system, serving only to divide the already relatively small Japanese radio industry. Any real potential for the defense of Japan had been sacrificed in favor of inter-departmental politicking. When the Americans returned to the skies of Japan in strength, the two Japanese air forces would meet them with too few aircraft, too poor early warning capabilities, and no real strategic plan.

What few hopes there were could be found in a new generation of fighters. During 1943 and 1944, Japanese fighters had lagged behind considerably their American opponents, largely due to their engines being less powerful. In the last months of the war, there were new models in service which gave some parity with the Allies. These new fighters were the Ki 84, N1K-J, Ki 100, and to an extent, the J2M3 Raiden, which was  at one point to be phased out by the Navy’s new N1K-J fighter. Given the desperate situation over the looming bomber offensive, and concerns over shortfalls in the supply of fighters, its production was instead boosted. With the proper planning, one or two of these fighter types could have taken up the bulk of the defensive effort in greater numbers, but the division of resources and the lack of any coherent strategy would prove fatal. In early 1945, the Japanese Air Forces had only some 500 fighters between acting in the defense of the homeland.

The Last Line – 302nd Air Corps

The 302nd Air Group would be the longest serving of the three units supplied with the Raiden to serve in the defense of Japan. The unit was formed March first, 1944, and was to be equipped with 48 Raidens, and 24 J1N1 night fighters, which was not irregular, as many other Japanese air corps operated more than one type of aircraft. This was often a mix of fighters and maritime bombers, though in the case of the home defense units, the combination of interceptors and night fighters was to give them a 24 hour, all weather defense capability.

The 302nd was deployed to Kisarazu, and later Atsugi, in Tokyo, to act in the defense of the Kanto region. The 302nd was the first, and among the most colorful of the three Raiden units established for the defense of Japan. It was a mix of mostly green airmen with a few veterans, among whom was possibly the most irregular officer in the service of the Japanese navy. Lieutenant Junior grade, Akatsumaki Saadaki had nearly a decade of service under his belt, and had built a steady reputation for disorderly conduct, drinking, womanizing, casual violence, and being an otherwise first rate combat pilot. His stories of his combat prowess and carousing were legendary, and according to fellow airman Lt.jg Sakai Saburo, all lies. Nevertheless, he would be a pillar of the unit alongside CPO Nakamura Yoshio, a veteran of the withering Solomon Island campaign, and Ensign Isozaku Chitose, an ace pilot with over ten years experience, from China to Rabaul. The unit was led by the fiercely patriotic Captain Kozono Yasuna, another Solomon island veteran, and a night fighter pilot with considerable experience.

Along with its odd mixture of experience, the 302nd also lacked for its new aircraft, with the priority of new Raidens being the 301st, elsewhere in the central pacific. The unit thus initially flew a considerable number of zeros, and older Raidens that had remained in Naval inventory, these being old preproduction J2M2’s, delivered in their orange test liveries. These proved to be a more challenging aircraft for the green pilots that made up much of the air group, and Lt.jg Akamatsu set aside the Raidens for his veterans, ensuring they were well versed in emergency procedures and dead stick flying. This would prove vital, given the poor quality of many of the aircraft they were given. It was only in May of the following year that they would eventually receive their 48 Raidens, though the Zeros would remain to substitute for unserviceable planes, and for the use of pilots not experienced enough for the more powerful Raiden.

The 302nd attempted several intercepts through 1944, most of these being lone, high flying F-13’s. They typically ended in failure. These aircraft were the photo reconnaissance model of the B-29 bomber, and free of a heavy bomb load, could prove very difficult to intercept without ample warning thanks to their high speed, and operating altitudes at and above 9 km. Other attempts to intercept larger formations also proved difficult, and success wasn’t noted until late in the year. On December 3, 1944, the 302nd sent 24 of its Raidens amongst the 74 Japanese fighters sortied against a raiding force of B-29’s. They saw some success, bringing down three B-29’s, with another two lost to the 244th Sentai’s “special attack” unit of the Japanese Army Air Force. Flying specially prepared, and armored, Ki-61’s, they performed ramming attacks against the American bombers. The ramming pilots survived their attacks, but Lt.jg Saadaki was deeply frustrated by these tactics, enough to discourage their use among his younger, and more impressionable airmen. There would be considerably more of these novices in their number, as many older veterans were eventually transferred away to establish new fighter units. In time, Lt.jg Akamatsu would also be transferred near the end of the war to train for a posting for a potential rocket-powered interceptor unit.

Shorn of some of its most venerable airmen, including Ens. Chitose, the 302nd would also soon find that following February, 1945, B-29 raids would be conducted at night, when only the unit’s J1N1s could pursue them. Despite the reduction in daylight raids, they would still have to contend with the presence of American fighters which began constant operations over Japan. The first encounters came as a result of Admiral Mitscher’s raids in mid February, 1945. Against them the Raiden crews proved their worth, claiming to have brought down eight Hellcats, for the loss of two Zeros, and three damaged Raidens. On the second day, they claimed a further seven Hellcats for the loss of two zeros, though the Raidens did not see combat that day. While they could contend well with the Hellcats, they would find a more dangerous opponent in the F4U Corsair, and the P-51D Mustangs, which they first encountered on April 7th.

Flying long sorties from Iwo Jima, American airmen fought cramps and the Pacific heat during their seven hour missions. Fatigued and bored, they nonetheless made for deadly opponents over Japan. The Mustang’s Packard Merlin engine was powerful from the sea level to high altitudes thanks to its two stage supercharger, its aerodynamic form saw it lose little speed in performing acrobatic maneuvers, and its laminar flow wings and sealed and balanced control surfaces gave it near unparalleled maneuverability at speeds other aircraft had stiff, and even unworkable controls. On the day they were first seen over the Kanto plain, they claimed three J1N1 night fighters, one D4Y2 dive bomber, and a Raiden. The heavier aircraft were capable bomber hunters when enemy fighters were of no concern, but as the Mustang had done in Germany when it made its appearance the previous year, it denied the use of these otherwise effective aircraft.

The 302nd would struggle to cope with the influx of Mustangs which made their presence immediate, and known. On April 12, while XXI Bomber Command was raiding the Musashino aircraft plant, they were joined by 104 P-51, who engaged Japanese fighters attempting to scramble, and strafed their airfields. Around the Kanto region, it thus became very difficult to actually reach the bombers given the presence of the P-51s, who were tasked with engaging the Japanese interceptors before they had a chance to make contact with the B-29s.

A small detachment of the 302nd was also sent to the southern home island of Kyushu, where they had more success against the smaller formations of raiders, which flew with a more modest escort. They still remained difficult targets, as bringing down a B-29 could take three passes, and the bombers were well defended by computer-assisted defensive guns.

In the last months of the war, the 302nd continued to take action against the American air forces which had become an immovable presence over Japan. However spirited the defenders may have been, they were contending almost exclusively with American fighter forces, and the B-29s were left to put entire cities to the torch by night. Between poor command and control facilities, crude early warning radar, and the constant inter service rivalry between the Navy and Army Air Forces, the defense of the Home Islands was failing. Despite having nearly two years to prepare for a potential strategic bombing campaign, there was no effective plan for the air defense of the Home Islands. In the final accounting, interceptors brought down a confirmed 74 Superfortresses, which flew some 31,300 sorties.

In the face of a disintegrating effort against an enemy that was only growing more numerous, the Japanese air forces continued their defense, largely without success. The Mustang, Hellcat, and Corsair, continued to roam the skies of Japan. On August 15th, In the last major battle between the air forces of the Japanese and US Navy’s, four Raidens and eight Zeros took off to engage a detachment of F6F Hellcats. Incensed by the declaration of surrender, the airmen of the 302nd ambushed the flight. Outnumbered and weighed down by external fuel and munitions, the Hellcats fought to escape, and in the ensuing dogfight, two Raidens and a Zero were lost for four of the US Navy’s fighters. An ace pilot was made in one Lt. Morio Yutaka, and the flight returned to base, concluding the final combat mission of the Raiden. The 302nd would mutiny in an attempt to continue fighting, but were discouraged when their messengers to other units were rebuffed and their commander fell ill. Divided and disheartened, they returned home.

Flight Characteristics and Pilot’s Remarks

The Raiden was fairly unique in that it was viewed very poorly by most Japanese airmen, yet American test pilots gave a fairly glowing account of it. Before all else, it must again be said that the strengths of the aircraft were not impressed upon Japan’s Naval Airmen before they were issued their planes. Its excellent rate of climb and impressive dive characteristics were noted in technical evaluations, but they were not emphasized enough in training. However, throughout its service, it did gain some good marks from Japanese pilots, notably from pilots in the Philippines who engaged American bombers at lower altitudes and found it far superior in this task than the other fighters available to them.

Most Japanese airmen coming to this aircraft did so with experience on the supremely agile, if slow, A6M Zero. The Raiden was practically the antithesis of this aircraft, with their strengths and weaknesses reversed. It thus proved categorically unpopular among Japanese Naval Pilots. The Raiden’s vibration at cruise and the poor build quality of the aircraft did nothing to improve its reputation. Poor visibility over the nose, rear, and the higher landing speed also presented challenges to those familiar with flying the Zero. They did, however, recognize it made for a superior interceptor over the A6M Zero, featuring an impressive rate of climb, and powerful armament. Its vertical maneuverability was also among the highest of all late war Japanese fighters, giving it a number of strengths over its allied opponents that the Zero lacked.

A wartime TAIC calculated performance report claims the Raiden was capable of climbing 4700 feet per minute (23.9 m/s) at its highest for its first supercharger speed at 4000 ft (1220 m), and 4100 feet per minute (20.828 m/s) at its second at 15,000 ft (4572 m). Its top speed was projected at 304 knots at sea level, 321 knots at 6,000 ft, and 369 knots at 17,500 ft. These figures are likely suspect and calculated based on an incomplete model, disagreeing considerably with other claims elsewhere.

A figure of top speed of 330 kts at 6km appears elsewhere in numerous, including Japanese publications, likely with better access to resources on the aircraft. It is also likely that its true performance lies somewhere in the middle. While this top speed isn’t particularly impressive, its maximum climb rate of approximately 4650 feet per second at sea level, was. This is considerably higher than the Mustang’s maximum rate of climb of 3600 feet per minute, when running at 67” manifold pressure and with a bomb rack on each wing, which would have been the case for those over Japan. These figures are likely more in line with its true performance, given that the aircraft was designed to achieve a very high climb rate, rather than the highest speed in level flight. Concurrently, its sustained turn performance was excellent compared to allied fighters, thanks to high power to weight ratio.

One of the most notable pilots to use the Raiden in combat was Lt.jg Akamatsu Sadaaki of the 302nd Air Group, who was as far removed from the picture of a Japanese wartime officer as was possible. He received his wings in the Naval Air Force in 1932, was a borderline dysfunctional alcoholic who was prone to insubordination, womanizing, striking those who irritated him, managed to survive the war without major injury, and he was said to have flown combat sorties drunk, among other wild claims. He would claim to have shot down over 200 enemy aircraft when sober, and 300 after a few drinks. He was officially credited with 27 victories. His eccentricities aside, he proved the Raiden was a capable combat aircraft in his role at the 302nd. In one engagement, he showed the excellent energy-fighting capabilities of the Raiden on April 19, 1945 when he and his wing man encountered a flight of five P-51s. With a height advantage, he dove beneath, and crept behind the enemy, shooting one fighter down, then and brought down another in a head-on pass before both sides broke away. His only real complaint was that the aircraft’s radius of action was short, but was otherwise seemingly the only advocate of this troubled aircraft.

With several airworthy Raidens having been captured in the battle for the Philippines, American evaluators were able to give an alternate perspective on the aircraft. Overall, it earned good remarks. The cockpit was spacious and well ventilated, especially valuable in the tropical climates of the pacific. The plane was judged stable on all axes, with good stall characteristics. Apart from a lack of warning, recovery was easy with no inclination to go into spins. Maneuverability was judged good, especially with the deployable fowler flaps that allowed for tighter turns. Harmony of control was acceptable but less than ideal, as the ailerons were heavy at cruise and became very stiff at 325 mph, the elevators also being noted for being light up to this speed, and with the rudder being judged effective at all speeds.

The engine ran roughly at the RPM’s for cruise, but at combat and takeoff power this was less pronounced. However, this rough running caused vibration and considerable noise, not enough to be considered excessive or uncomfortable, but enough to be noteworthy. The poor workmanship of the engine would make itself known during testing when an oil delivery hose failed during a long flight, causing the engine to seize and force the pilot to make a dead stick landing.

One Allied evaluation pilot, who filed a detailed report on the plane, would claim it to be the best of the Japanese aircraft he’d flown, which notably included the Ki 84. Overall, the aircraft judged well thanks to its good stability, stall characteristics, comfort, good combat related performance, and its combat flaps. Ironically, it was also said to have had good landing characteristics, which suggests much about the different expectations in aircraft handling between American and Japanese airmen.

Construction

The fuselage of the J2M was of a traditional construction, save for the deeper placement of the aircraft’s engine. This resulted in the spindle-like shape of the aircraft’s fuselage,  allowing for the fitment of a larger engine while still retaining a clean aerodynamic shape. It was of a typical duralumin monocoque construction, with 18 structural bulkheads and former sections from the engine to the tail. It was, however, noteworthy for the use of Sumitomo Super Duralumin, which could boast of higher strength than its contemporaries, comparable with post war 7075 grade aluminum alloy, and late war American alloys which had been developed in response to captured Japanese examples.

It was among the few Japanese fighters to incorporate protection for the pilot, though compared to foreign designs it was very lightly armored. This consisted of an armored steel headrest with a thickness of 8mm, and an armored glass screen, 50mm thick, at the front of the cockpit. In service, these plates were occasionally removed to lighten the aircraft.

From the prototype to the production models there were two major fuselage alterations, namely the addition of a canopy which sat higher atop the air frame to improve visibility and resolve optical issues, and the addition of an additional oil cooler for the engine. A more minor, yet essential, alteration was to shift the position of the tail wheel retracting mechanism, as on early models it could press against the elevator control, and render the aircraft uncontrollable.

The wings incorporated laminar flow theories into their design, which gave the aircraft improved dive performance, and provided high drag reduction. They also improved control through high speed ranges by keeping the destabilization of airflow across the wing’s surface, known as compressibility, from occurring up until the aircraft reached higher mach numbers. Each wing had landing gear which deployed outward, driven by an electric motor which also actuated the tail wheel and flaps. Fowler flaps were used to give the aircraft a tighter turning circle at the cost of speed, they could be deployed via a button on the control yoke, and set the flaps at a 16 degree deflection so long as the button was held.

Cooling was originally provided by an airflow, and later engine driven, fan which drew air through a small annular radiator at the nose of the aircraft. This proved to be inadequate due to the small inlet at the nose of the aircraft and the limitations of the engine driven cooling fan, forcing the addition of an under-nose radiator on the J2M2 model. This cooler was also enlarged on the next model, the J2M3, to provide better cooling for the longer, higher power climbs these interceptors would be making.

The plane was powered by various models of the Mitsubishi Kasei, a 42.1 liter, two-row, 14 cylinder radial engine equipped with a Mitsubishi fuel injection system, and a single stage, two speed supercharger. The original was the Kasei 13, MK4C, which operated at a reduced output of 1,420hp, this was done to try and keep issues of vibration to a minimum, but this failed due to issues with the constant speed propeller governor, which drove a three bladed propeller. It was noteworthy for its air driven cooling fan which sat at the front of the engine, and a 50cm extension shaft which was shrouded in an elongated reduction gear housing unit. Technical issues with this engine, and its insufficient output saw it abandoned for the Kasei 23.

The Kasei 23, MK4R, reduced the length of the extension shaft to 30cm, incorporated an engine driven cooling fan. Vibration issues were eventually relieved through the use of rubber buffers on the engine mounts and adjusting the propeller balancing mechanism along with replacement of the constant speed unit, which then drove a four bladed Sumitomo metal propeller. Some vibration was still noted in flight, but not enough to significantly affect the combat performance of the aircraft. It likely had an impact on the serviceability of Raiden, but far less so than most of the aircraft being produced by an inexperienced workforce.

This engine was further developed into the Kasei 23a, MK4R-A, with the addition of a methanol-water injection system. The anti-detonation properties thus allowed the engine to run at higher manifold pressures, allowing for an output of 1800hp. It was also equipped with individual exhaust stacks, providing thrust augmentation. This was the primary engine for the J2M2 and J2M3, after the Raiden’s protracted development. The engine had a bore and stroke of 150x170mm. It had a diameter of 134 cm, with a length of 274.32 cm.

At an RPM of 2600 and +450 mmhg over atmospheric pressure, the engine produced 1800 hp at takeoff. It produced 1575 at its first supercharger speed at 1800 m (5905 ft), and 1410 hp at its second speed at 4800 m (15748 ft). It could hold its maximum power setting for 1 minute, and military power, 2500 RPM at +300 mm hg, for 30. Its maximum continuous rating was at 2300 RPM and +150 mm hg of manifold pressure.

Fuel tankage comprised a pair of tanks at the wing roots containing 90 liters of aviation gasoline, along with a fuel tank ahead of the cockpit which initially contained 410 liters, later reduced to 390 liters after plane 3003. A centerline detachable drop tank could also be carried, increasing fuel supply by 250 liters. The oil tank was mounted aft of the engine and had a capacity of 60 liters. The methanol-water tank was sandwiched between the oil and fuselage fuel tank for a capacity of 120 liters. The aircraft was serviced with 92 octane aviation gasoline.

The initial armament of the J2M2 Raiden comprised a pair of 7.7mm Type 97 machine guns mounted in the engine cowling, and a pair of wing mounted 20mm Type 99 Model 2 machine guns. The Type 99 was designated a machine gun, as compared to other calibers in use by the navy it was quite small and did not warrant being referred to as a “cannon”.

The Type 97 was a derivative of the Vickers class E aircraft machine gun. Each weighed 11.8 kg, was 104 cm in length, was belt fed, and had a rate of fire of 900 rounds per minute. The Type 99 no.1 model 4 20mm machine gun weighed 23 kg, measured 133 cm in length, was belt fed, and fired 520 rounds per minute, supplied with a 210 round belt.

This armament was also to be used for the J2M3 before the cowling machine guns were removed and a second pair of wing mounted 20 mm machine guns were added. These Type 99 no.2 model 4 20mm machine guns were mounted inboard of the initial guns, weighed 34 kg, measured 189 cm in length, were belt fed, and fired at 490 rounds per minute, with a 190 round belt. These featured a longer barrel and had a higher muzzle velocity.

A very small number of J2M3’s were equipped with a pair of 30 mm Type 5 machine guns in place of the Type 99 no.2’s. These each weighed 70 kg, had a length of 207 cm, fired 500 rounds per minute, and were belt fed.

A very small number of Raidens received an upward firing 20mm mounted behind the cockpit for use against bombers. It was used only with the 302nd air group, and installed at the insistence of its commanding officer, a night fighter pilot who thought it would be useful against heavy bombers. Little has been written of its configuration or use, with the modification being stated to have been very unpopular with pilots who disliked the added weight of the questionable weapon.

A pair of 60 kg general purpose aviation bombs could be carried on outer wing shackles. They were compatible with air to air phosphorous bombs, though this capability was likely never used.

Attempts to produce high altitude series were made, though none produced a combat ready aircraft. The J2M4 possessed a turbosupercharged Kasei 23c engine with a slightly lengthened fuselage to accommodate the turbine, but it proved too unreliable for service. It proved capable of reaching 315 kts at 9.2 km. A second high altitude series was attempted in the J2M5, which took a more modest path in using a Kasei 26a, utilizing a three speed supercharger. It proved a far more reliable means of boosting high altitude performance, allowing it to make 331 kts at 6.8 km. It had a fairly small production run, but the escalating bombing raids against the Japanese mainland made any major modifications to the Raiden unacceptable, as they would have reduced the production output of an already much needed aircraft.

Variants

J2M1: Prototype series, Kasei 13, early windscreen. 3 produced. First aircraft completed March, 1942, flown March 23.

J2M2 Model 11: Kasei 23, new canopy design, air driven cooling fan replaced with engine driven, chin oil cooler added, propeller changed with new governor, numerous other mechanical improvements. Two Type 97 7.7mm guns in cowl, two Type 99 20mm guns in wings. Kasei 23a later retrofitted, vibrations issues reduced. First aircraft completed October 1942, first flown October 13.

J2M3 Model 21: Kasei 23a, oil cooler enlarged. Four Type 99 20mm guns in wings. Most produced type. First aircraft built October 1943.

J2M4 Model 32: Prototype series, Kasei 23c turbosupercharged engine, unreliable. Only 2 produced. First aircraft built August 1944, first flown September 24. Project canceled in February 1945.

J2M5 Model 33: Production series, finished trials May 1944, shelved. Kasei 26a with three speed supercharger. Enlarged cockpit frame to improve rearward visibility. 34 produced. First flown May, 1944.

J2M6 Model 31: Prototype, J2M3 with canopy and cockpit from J2M5. First aircraft built February 1944.

J2M7 Model 23: J2M3 with fuselage modifications to improve rearward visibility. None built.

Production

The Raiden was built at Mitsubishi Airframe Works No. 3 at Nagoya, and later at dispersal facilities and the Naval depot at Kanagawa. Production varied drastically, especially early on when cancellation of the program was being considered, only for it to be brought back when the need for interceptors of any kind became dire. The relationship between the plant and government was deeply strained during wartime, production decisions with long term impacts were judged to have been made too often by post war American evaluators, and the plant officials were disparaging of the government’s involvement in their business. Stress was felt strongest over production orders, where the military changed its mind too often in regards to order sizes and modifications. Where Mitsubishi would have preferred large orders with little modifications between batches, the military vacillated in their procurement.

As the war continued, more and more conscripted labor was used, and in its last year, a large number of teenage workers. They were not only inexperienced, but were categorized by the plant managers as “inefficient, inept, and indifferent”. To complicate matters, they had friction with the regular plant employees, a factor that was likely also cultural as these conscripts often came from territories outside Japan. Morale at the plant was low.

Nagoya Airframe Works No. 3, and its dispersal facilities produced 493 aircraft, with a further 128 being produced by the Koza Naval Air Arsenal in Kanazawa. Unlike in Germany, dispersal efforts largely failed due to poor long term planning and the USAAF’s ability to track the progress of alternate production sites. Production never ceased, but the quantity and quality of the aircraft that left the production lines was heavily impacted. According to Horikoshi Jiro, the efforts to disperse the factory were conducted too blatantly, and had the effect of dividing up experienced plant personnel and construction crews at a time where they were already spread too thin. The build quality of the J2M was thus fairly dubious during 1944 and 1945, which was well understood by aircrews.

Production Mitsubishi, Nagoya, All Types	January	February	March	April	May	June	July	August	September	October	November	December
1942			1	1	1	2	2	1	1	1	1	2
1943	0	0	1	2	0	0	3	4	5	16	21	22
1944	17	26	9	22	39	44	34	22	16	20	18	7
1945	17	12	29	16	0	8	7	27
Production Koza, Kanagawa Naval Depot	January	February	March	April	May	June	July	August	September	October	November	December
1944					1	0	0	1	2	3	4	6
1945	13	8	23	15	10	20	22	0

Specifications

J2M3 Raiden	Specification
Engine	Kasei 23a MK4R
Engine Output	1800 hp
Gross Weight	2861 kg
Empty weight	2191 kg
Maximum Range	968 nmi (calculated)
Maximum speed	330 kts at 6km
Armament	4x 20mm  Type 99 Model 2, no.’s 1&2
Crew	1, Pilot
Length	9.69264 m
Height	3.93192 m
Wingspan	10.78992 m
Wing Area	11.7058 m2

Conclusion

Few full-scale production aircraft had the developmental difficulties of the J2M Raiden, and of those that did, few of those ever reached the front line in appreciable numbers. Despite its development running through nearly the entire war, Horikoshi’s troubled plane did eventually find its way into service. Unfortunately it did so without pilots being well informed of the aircraft’s strengths, with most taking a dim view of the aircraft, one which ran roughly and was less maneuverable than the Zeros they traded it for. Yet, in service, the aircraft proved quite capable in combat, and received glowing endorsements from Allied evaluators.

Illustration

 

Credits

Written By Henry H.

Edited By Henry H.

Illustration by Oussama Mohamed “Godzilla”

Sources:

Primary:

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Army Air Arsenal And Navy Air Depots. Corporation Report No.XIX (Airframes and Engines). United States Strategic Bombing Survey Aircraft Division. 1947.

Japanese Air Weapons and Tactics. Military Analysis Division. 1947.

Japanese Aircraft Performance and Characteristics TAIC Manual No. 1. Technical Air Intelligence Center. 1944.

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Horikoshi Jiro. Eagles of Mitsubishi: The Story of the Zero Fighter. 1992.

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Samuel J. Cox. H-051-1: The Last Sacrifices. 2020.

Mitsubishi Kasei 23 ‘Ko’, Ha 32 Model 23 ‘Ko’, Radial 14 Engine. Smithsonian Air and Space Museum.

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