Mizuno Shinryu II

In June 1944, the first Boeing B-29 Super­fortresses appeared over Japan. It was the start of a bombing campaign that would see key Japanese cities, infrastructure and indus­tries reduced to ashes through conventional and firebombing raids. With the aircraft industry being a priority target, the Kaigun Koku Hombu looked to ways to combat the B-29 menace. One concept was a point defence interceptor that could quickly rise to meet the bombers and so the Mizuno Shinryu II was born. However, the development of the Shinryu II (Shinryu meaning ‘Divine Dragon’) began with designs for a far more conven­tional craft.

In November 1944, the Kaigun Koku Hombu looked into the possibilities of an air­craft to undertake shimpu missions. While the mission was not unique, the fact that the
aircraft being investigated would be a glider was. The Kaigun Koku Hombu envisioned that gliders would be launched with rocket boosters from caves or shore positions and pilots would guide the aircraft and the 100kg (220 lb) explosive payload inside it into Allied ships or tanks should the Japanese home islands be invaded.

The Kaigun Koku Hombu assigned the Dai – Ichi Kaigun Koku Gijutsu-sho at Yokosuka the task of turning the glider into reality. The pro­ject was led by Shigeki Sakakibara who staffed a number of teams that would each be responsible for one part of the glider. The dif­ferent sections were the wings, the fuselage, control surfaces, aerodynamic testing and test flights once the prototype was complete. The Kaigun Koku Hombu gave instructions that the glider must be built from as much

wood as possible. This restriction was imposed for two reasons. The first was that in using wood and keeping the use of metal to an absolute minimum, the glider could be manufactured in any small shop using only wood working tools, and secondly, as a con­sequence, what metals were available would be conserved for other military uses.

Much of the glider’s design was conceived by Yoshio Akita. A number of concepts were discussed and sketched and after much deliberation among Akita and his teams the design was complete by May 1945, and Mizuno, a small aircraft manufacturer, had almost finished the prototype. The glider was very simple and used a high-wing monoplane form. The straight and flat wings were wide but had a short span and were designed to ensure that the glider was easy to handle given that inexperienced pilots would be at the controls. Also, the planform would be able to accommodate the rocket engines that were to be used to boost the glider into the air. The pilot sat in an open cockpit.

The design was sent to the Kaigun Koku Hombu for review. Sakakibara studied the plans and projections and after his analysis it was felt the glider was flawed and changes were necessary. After these had been made the design was approved. Work began on the revised JinryQ as the glider was now called by the middle of June 1945. To hasten the con­struction, the finalised blueprints and work plans for the Jinryti were drawn up even as the components for the first prototype were being built. Construction of the JinryQ was again given to Mizuno. Working around the clock, the company completed two proto­types with such speed that wind tunnel test­ing of the design was still underway. In fact, the first flight of the Jinryti occurred even before the results of the testing had been pro­vided to Tonsho and Sakakibara.

Tashiichi Narabayashi was the pilot who flew the maiden flight in mid-July 1945 at the airfield in Ishioka, a city located in Ibaraki pre­fecture, about 90km (56 miles) northeast of Tokyo. The Jinryti was towed into the air by a Tachikawa Ki-9 (known to the Allies as Spruce) piloted by SaburO Fujikura, a man known for his skill in flying gliders prior to the beginning of the war.

For the first test, Narabayashi assessed the Jinryti’s handling. On landing, his opinion was that the glider was stable and possessed good handling characteristics. For the second flight Narabayashi would investigate the Jinryti’s diving capability and after a few bounces on the ground the Ki-9 and the Jinryti took off. At a height of 2,300m (7,545ft), Narabayashi went to cast off from the Ki-9 but found that the tow rope release had stuck; however, he was able to cut the rope and proceed with the test flight. When Narabayashi put the Jinryti into a dive and had reached 300km/h (186mph), the glider began to vibrate to such a degree that he was unable to read the gauges. Pulling the nose up to bleed off speed, Narabayashi discovered that the vibra­tions ceased. During his descent Narabayashi examined the vibrations and after landing the issue was reviewed. The conclusion was that the tail was not sufficiently reinforced and the vertical stabiliser was too small. The JinryQ was modified by adding some strengthening in the tail and the fitting a second stabiliser. The changes were later validated both in the air and in the wind tunnel testing of the mod­ified JinryQ model. Interestingly, before flying the JinryQ, Narabayashi had suspected that the aircraft would have stability problems which, as was seen, proved to be the case.

With the handling and flight characteristics of the JinryQ proven, the testing moved to the next phase – that of powered flight. The glider was relocated to an airfield in Kasumigaura, about 19km (12 miles) north of Ishioka. Here, the JinryQ was modified to accept a group of three Toku-Ro 1 Type 1 rocket engines that together would produce 661 lb of thrust dur­ing a 10 second burn. Testing of the rocket array showed two serious flaws. The first was the quality of the rockets that resulted in a number of failures. The second was the inconsistency of the burn times. Narabayashi noted his concerns and forwarded them to Major Suganuma who had been placed in charge of the JinryQ project. In addition to expressing his doubts about the rocket engines, he also stated that the JinryQ would be unsuited for shimpQ missions because, despite the changes made to the glider to improve the flight characteristics, it was a challenging aircraft to fly. Narabayashi sug­gested that instead of being used for shimpQ operations the glider should be modified to take six rocket engines each with a 30 second burn time. He estimated that at maximum burn the JinryQ could attain a speed of 750km/h (466mph), and for weapons he envi­sioned that it could carry ten explosive charges adapted from artillery shells used by the IJA in their 100mm guns (likely the Type 92). Not only did Narabayashi agree that the JinryQ could be used against tank and ships but added that it could also be used to attack US B-29 bombers. Despite the issues with the rockets work continued on preparing the Jin­ryQ for powered flight.

Major Suganuma, however, would become the catalyst for the ShinryQ II’s continued development. Taking Narabayashi’s concerns onboard, Suganuma formed a team to revise the JinryQ and produce a design for an inter­ceptor rather than a glider; Suganuma was especially interested in this idea since he had access to rocket engines that promised 32 sec­ond burn times. Two people were retained from the JinryQ project: Sakakibara, the lead designer, and Yoshio Tonsho who would over­see the construction of the prototype. YQjiro Murakami was tasked with the aerodynamic testing of the ShinryQ II. All of those assigned to develop the ShinryQ II were ordered by Sug­anuma to maintain the utmost secrecy.

Unlike the JinryQ, the ShinryQ II was to be built from the outset as an interceptor. Sakak­ibara would use a canard design that made this the second Japanese aircraft to be devel­oped during the war with such a feature (the first was the KyQshQ J7W Shinden on page 84). In addition, the main wings had a plan – form similar to a cropped delta. These design features were included as a means of ensur­ing stability in flight as well as good handling characteristics. Since the average Japanese pilot had little experience with canard equipped aircraft, the ShinryQ II had spoilers fitted into the top of each main wing. Each spoiler was able to rotate between 60° and 90° and if the mechanism for controlling the spoilers was damaged, they would automati­cally return to the closed position. The pilot was provided with a canopy covered cockpit.

For power, the ShinryQ II was to use four Toku-Ro 1 Type 2 rocket engines located in the rear of the fuselage. Each engine provided a 30 second burn time and all together up to 600kg (1,3221b) of thrust could be delivered. Two rockets would be used to get the ShinryQ II airborne while the other two engines would be used when making the attack. There was a concern regarding the operating tempera­tures of the Toku Ro rockets and two meth­ods of cooling the engines were considered. The first would have utilised an air-cooled combustion chamber that would have required an air inlet using a bayonet mecha­nism in order to maintain air flow across the chamber. It also would have required specific positioning of the fuel injectors so as not to have the air flow disrupt the injection process. The second method would use injectors which sprayed a water and alcohol mixture onto the rocket nozzle, cooling it. In reviewing the two solutions for cooling, it was determined that the water/alcohol system would be the simplest to implement.

No provision was made for a wheeled land­ing gear system and design skids were used. A nose skid was provided with a basic spring suspension to absorb the landing forces. Under each wing was a non-sprung skid arrangement supported by two struts. For take-off the ShinryQ II was to use a two­wheeled dolly similar to the one used by the

Mitsubishi J8M SvOsui. Once airborne the pilot could jettison the dolly. In addition to con­ventional runway take-off procedures, other methods for launching the Shinryd II were considered but what exactly these were is not known. It can be speculated that towing the Shinryu II aloft was one consideration. Another may have been air dropping the Shin – гуй II in the same manner as the Kugisho MXY7 Oka. In both cases this may have pre­served two of the rocket engines which would have been used up had the Shinryu II taken off from the ground.

In order to combat the B-29, which could operate at altitudes up to 10,241m (33,600ft), the Shinryu II was to be equipped with a pres­surised cockpit or, if such a cockpit proved problematic, the pilot would wear a pressure suit. For weapons, the Shinryu II was to be armed with eight rockets. Attached to the inside of the rear landing skid arrangement were four tubes, one on top of the other and angled downwards, which contained the rockets.

There has been some conjecture as to the mission objective of the Shinryu II. Some sources make the case that the Shinryu II was to be used like the Oka while others come to the conclusion that the Shinryu II was to attack armoured ground targets such as tanks. In both cases these sources state that the nose of the Shinryu II contained an impact fused explosive warhead and once the rocket arma­ment was expended, the pilot would crash the aircraft into his final target using the war­head to deliver the coup de grace. However, analysis of the Shinryu II shows that neither mission was likely. The aircraft would have been far more complex to build than the Showa Тока or Oka and the Shinryu II was constructed for manoeuvrability, high altitude operation and the means to land. In addition, using the Shinryu II for shimpfr missions against tanks makes little sense when there were other simpler and more effective means (both already in service and under develop­ment) to eliminate armour. Perhaps this is a case of the Jinryu glider’s role being applied to the ShinryCi II, or an assumption based on the fact that, like the UN’s other special attack air­craft such as the Nakajima Kitsuka, Kawanishi Baika and Showa Тока, the Shinryti II pos­sessed no letter/numerical designation. So, by extension, the Shinryu II must also have been a special attack weapon. This, of course, is not to say that the pilot could not choose to use the Shinryti II as a shimpti aircraft.

As an interceptor, the Shinryu II had a simi­lar role to the Mitsubishi J8M Syusui and the German Bachem Ba349 Natter for which the Japanese were aware of and obtained data on (although the plans never made it to

Japan). Like the J8M and Ba349 and due to the limited range afforded by the rocket engines, the Shinryu II would have to be posi­tioned close to targets that were likely to be bombed. And like the J8M, the Shinryti II would have used a jettisonable wheeled dolly to take-off while firing a pair of its rocket engines. Unlike the J8M which burned up all of its fuel at once, the Shinryti II had a second set of rocket engines which could be used to sustain flight endurance or to increase speed during the attack. In the same way as the Ba349, the Shinryti II would be armed with rocket projectiles, likely fired as a group to affect a spread pattern, to bring down the bomber target. Finally, akin to the J8M, once the fuel and ammunition were expended, the Shinryu II would glide back to its base to be recovered, refuelled and rearmed.

The Shinryti II would never be built because the end of the hostilities in August 1945 terminated any further work on the design. Likewise, the Jinryu glider would never fly under power. After the failure of the rocket motors during ground tests, the war came to a close before more suitable and reli­able motors could be acquired and tested. Mizuno completed a total of five Jinryu glid­ers. As a note, Jinryu is the known name for the first Mizuno glider. For the purposes of this text, the author used Shinryti II to differentiate the interceptor from the glider. The kanji is the same for both spellings but is pronounced differently. Both translations of Jinryu and Shinryti mean ‘Divine Dragon’. Shinryti II is also used in contemporary texts and as such, is used here for recognition purposes. Whether the interceptor would have carried the same name as the glider is unknown.

Contemporaries Blohm und Voss BV40 (Germany), Zeppelin Fliegende Panzerfaust (Germany), Heinkel P. 1077 Julia (Germany), Junkers EF127 Walli (Germany), Messerschmitt Me 163B (Germany), Bereznyak-Isayev BI (Russia) Specifications in parenthesis are for the Shinryu II and are estimates only.
Type	Special Attack Glider (Interceptor)
Crew	One
Powerplant	Three Toku-Ro Type 1 rockets with a total combined
thmst of 400kg (881 lb) with a bum time of 10 seconds (Four Toku-Ro
Type 2 rockets with a total combined thmst of 600kg/l ,322 lb with a bum
time of 30 seconds)
Dimensions
Span	7.00m	22.9ft
Length	7.60m	24.9ft
Height	1.80m	5.9ft
Wing area	11m2	118.4ft!
Wing loading	N/A	(N/A)
Power loading	N/A	(N/A)
Weights
Empty	N/A	(N/A)
Loaded	N/A	(N/A)
Maximum	N/A	(N/A)
Performance
Max speed	300km/h	186mph
Cruise speed	110km/h	68mph
Range	4km	2 miles
Endurance	(Shinryti II) 1.3 minutes
Ceiling	400m	1,312ft
Armament	100kg (2201b) of explosive (8 unguided rockets)
Deployment	None. A total of five protoptype Jinryu gliders were
built by Mizuno. The Shinryti II remained a design board aircraft.

Imperial Japanese Navy

Japan shared a fundamental flaw with Ger­many in regards to not developing a bomber capable of long range missions. The lack of this capability is considered by some to be a pivotal nail in the coffins of each country dur­ing the war. In both cases, efforts to develop such a bomber came too late to affect the out­come of the conflict. Although the Japanese had considered the need for such a bomber at the outset of hostilities – as had the Ger­mans with the disastrous Heinkel He 177 Greif – very little happened until the need was dire, and by then the noose was tight, chok­ing any hope for putting a long range bomber into service.

The main cause of this apathy was the early success in the Pacific theatre where the short and medium range bombers then in use by the Japanese were adequate to fulfil the needs of the IJA and UN. With the entry of the United States into the war a formidable prob­lem arose. Geography put the military machine of the US far out of reach of Japan.

When the tide of war turned against the Japanese, it was soon realised that some means to attack the US mainland had to be acquired, not only to destroy the war industry of America but to ravage the civilian popula­tion centres to reduce morale and bring the war to the US doorstep. In consequence, the US would have to allocate or divert resources to increase the defence of the homeland which would affect the war on other fronts. As history was to show, the Japanese did suc­ceed in launching attacks against America, but only in the form of the Fu-Go balloon bombs and isolated attacks on the west coast from submarine-launched float planes. None had much of an effect.

There were some early attempts to pro­duce a long range bomber – for example, the Mitsubishi G7M1 Taizan (a 16-shi project) – plus designs that were actually built such as the Nakajima G5N Shinzan and Nakajima G8N Renzan. The Shinzan was not a success and the Renzan failed to reach operational
service as a combat aircraft, let alone reach America and return.

It was to be Nakajima who would attempt to provide a strategic long range bomber capable of bringing the war to America. The man behind the project was Chikuhei Nakajima, chairman and engineer of Nakajima Hikoki K. K. Motivated by his fears over the inability of the Japanese to reach and destroy US indus­trial capacity, Chikuhei tried to convince the UN and the IJA of the need for a strategic bomber. However, officials from both services refused to consider his ideas. Thus, without official sanction or request, Chikuhei invested a portion of Nakajima’s resources to draft designs for a bomber that could take-off from Japanese bases, cross the Pacific, attack tar­gets on the West Coast of America and return to either their original bases or elsewhere in Japanese or Axis held territory. Nakajima gave the design work the name ‘Project Z’.

On 29 January 1943, Nakajima began the task of assembling drafts and studies for the

design of the bomber, along with reports which studied the feasibility and problems of production. On the completion of this stage in April 1943, he again pitched the concept to both the IJA and the UN. This time, neither service turned Nakajima away. However, despite the information Nakajima had assem­bled for the proposed bomber, and despite both services now accepting the need for such an aircraft, the IJA and the UN also pro­duced their own ideas. Not surprisingly, the two services had differing opinions on the requirements for the bomber. The IJA desired a type that could operate at 9,998m (32,800ft) and carry a heavy defensive armament. By contrast, the UN wanted a bomber capable of flying at a height of 14,996m (49,200ft), an alti­tude where interception would be minimal and thereby allowed a lighter defensive weapon load to be carried. Furthermore, the IJN wanted the bomber to take-off from Japan, bomb any target within the US, then utilise bases in Germany or German held ter­ritory to land, as opposed to making a round trip.

Though there were a number of variations of the aircraft during the Project Z develop­ment, three basic designs of what became the Fugaku emerged. The project presented by the IJA used a ‘tail sitter’ undercarriage, featured dual vertical stabilisers and bore some resemblance to German designs. It also had a rounded off nose similar to the Boeing B-29 Superfortress and Messerschmitt Me 264 ‘Amerika’ bomber. The UN’s proposed design used a tricycle landing gear arrange­ment and rounded nose but utilised a single vertical stabiliser. Nakajima’s proposal kept the single vertical stabiliser but had a stepped nose much like that used on the G5N Shinzan which the company had previously worked on.

By June 1943, Nakajima had received plans from the IJA and IJN, reviewed them and begun work on drafting a final design. To con­tinue the research and further development and study the Project Z aircraft, the Army and Navy Aviation Technical Committee was formed on 9 August 1943. The IJA delegation was headed by Captain Ando. Later in August, Chikuhei Nakajima prepared a thesis entitled ‘Strategy for Ultimate Victory’. Chikuhei used his personal clout to make sure his document reached not only IJA and IJN officials, but also politicians and even Prime Minister Hideki Tojo. His thesis was laid out in six chapters and contained Chikuhei’s plan for defeating the US as well as defending Japan. The key component was the Project Z bomber which he proposed could be used to destroy US air­fields as a means to deny the US the ability to launch raids against Japan. This suggestion was in part due to his belief that Japanese air forces were not strong enough to repel a bombing raid. Another facet of the thesis was the use of the bomber to attack the US war industry. Without materials and oil, the US could not produce aircraft, tanks and other weapons. More importantly, he added, the Japanese should use the bomber to destroy the Soviet military industry as a means to sup­port Germany. This implied that Nakajima could provide Germany with such long range bombers.

The Project Z bomber would employ an all metal stmcture with the wings mounted in the mid-fuselage position. The plane was envisioned to be powered by the Nakajima Ha-54, 36-cylinder radial engine, also known as the D. BH. The Ha-54 was, in fact, two Ha-44 18-cylinder radials paired together. It was pro­jected that the Ha-54 engine could produce up to 5,000hp and that six of these would be sufficient to propel the bomber to a generous maximum speed of 679km/h (422mph). Each engine would drive two contra-rotating, three-bladed propellers with a 4.5m (14.7ft) diameter. The Ha-54 engine, however, would not be ready for some time (and as events turned out, by war’s end it was still only a pro­totype engine and problems with cooling the power unit through the use of a ducted cowl­ing were never solved). Therefore, Nakajima had to settle for the experimental NK11A (Ha-53) which, while also in development, was expected to be ready for trials. The draw­back was that the NKUA was expected to muster only 2,500hp and this would certainly have lowered the performance estimates. The introduction of the NK11A meant that a revision of the Project Z airframe became necessary.

The bomber’s ceiling was estimated to be 15,000m (49,212ft) and it was believed that a heavy defensive armament was not neces­sary as the high altitude would offer protec­tion from fighter opposition. To a lesser extent the projected speed would also reduce vul­nerability. Consequently, the bomber would carry at least four Type 99 20mm cannons, but contemporary illustrations of the bomber often show a much heavier armament. This may be a result of having to settle for the less powerful NK11A and any speed/altitude advantage would have been lost, so an increased weapon load would have been necessary to protect the aircraft. Typically, illustrations show two cannon mounted in the tail, two in the nose, two twin-cannon tur­rets placed in the front and rear of the fuse­lage top and at least one belly turret. Variations included waist gunner stations. For a normal bomb load, the bomber was expected to carry up to 20,000kg (44,092 lb) of

Contemporaries

Convair B-36 Peacemaker (US), Convair XC-99 (US), Messerschmitt Me 264 and Me 264B (Germany), Junkers Ju 390 (Germany), Junkers EF100 (Germany), Messerschmitt Me P 08.01 (Germany), Tupolev Tu-4 (NATO codename Bull) (Russia), Tupolev Tu-85 (NATO codename Barge) (Russia), Tupolev Tu-70 (Russia), Vickers-Armstrong Victory Bomber (UK)

Specifications in parentheses refer to the Fugaku specifically. All other specifications refer to the primary Nakajima Project Z design.

Type Long range strategic bomber

Crew Six to ten (seven to eight)

Powerplant Six Nakajima Ha-54 36-cylinder, air-cooled radials developing 5,000hp at engine start, each driving two alternating stroke, contra-rotating three bladed propellers of 4.5m (14.7ft) diameter/Six Nakajima NK11A [Ha-53] 18-cylinder, air-cooled radials developing 2,500hp at engine start and each driving a alternating stroke, four-bladed propeller of 4.8m (15.7ft) diameter

Dimensions Span 64.98m 213.2ft (Fugaku) 62.97m 206.6ft Length 44.98m 147.6ft (Fugaku) 39.98m 131.2ft Height 8.77m 28.8ft (Fugaku) 8.77m 28.8ft Wing area 352.01m! 3,766.8ft2 (Fugaku) 330.00m2 3,552ft2 Wing loading, 348.60kg/m! 71.4 lb/ft2 normal (Fugaku) 126.94kg/m2 26 Ib/ft2 Wing loading, 456.99kg/m2 93.6 lb/ft2 loaded (Fugaku) 211.89kg/m2 43.4 lb/ft2 Power loading, 5.44kg/hp 12 Ib/hp normal (Fugaku) 3.76kg/hp 8.31b/hp Power loading, 7.21kg/hp 15.9 lb/hp loaded (Fugaku) 6.30kg/hp 13.9 lb/hp Aspect Ratio 12.1 (N/A) Weights Empty 65,000kg 143,3001b (Fugaku) 33,800kg 74,5161b Loaded 122,000kg 268,9631b (Fugaku) 42,000kg 92,5941b Max loaded 160,000kg 352,7391b (Fugaku) 70,000kg 154,3231b Performance Max speed 679km/h 422mph at 10,000m at 32,80811 779km/h 484mph (Fugaku) at 10,000m at 32,808ft Take-off run (Fugaku) 1,020m 3,347ft Range 16,499km 10,252 miles (Fugaku) 16,499km 10,252 miles Max range 17,999km 11,184 miles (Fugaku) 19,400km 12,054 miles Ceiling 15,000m 49,212ft (Fugaku) 15,000m 49,212ft Armament Four Type 99 20mm cannons (up to 12 cannons depending on the source) and a maximum bomb payload of 20,000kg/44,092 lb

Deployment

None. The ‘Project T and Fugaku aircraft existed only as paper designs.

bombs, but in the case of anti-shipping mis­sions, torpedoes could be carried (see below). For attacks on the United States, the bomber would carry only up to 5,000kg (11,023 lb) of bombs.

As work continued on the Project Z, plans were made to assemble and house the bomber’s production line. By the fall of 1943, these plans had been completed and con­struction of the new facility had begun. By January 1944, the Project Z moniker was dropped and changed to the Fugaku which means ‘Mount Fuji’.

As it was, more pressing demands on Nakajima resulted in less and less work being done on the Fugaku. To compound the prob­lem, by the time the design was nearing com­pletion, Japan was on the defensive and chances of producing the Fugaku, let alone using it to attack America, were about nil. The IJA believed that there was no probability of the Fugaku being built and therefore aban­doned the project, leaving the UN as the sole remaining party involved. Even the Gunjusho (the Ministry of Munitions) felt the Fugaku was impossible to realise and ordered Kawanishi to design a new long range bomber. Unfortunately, the Gunjusho failed to inform the IJA, UN and Nakajima about the Kawanishi bomber, which was known as the ТВ. When the new bomber project was dis­covered, a hail of protests and arguments erupted that hampered not only the develop­ment of the Fugaku but all long range bomber projects including the ТВ which was soon cancelled.

However, it was the fall of Saipan in 1944 that sealed the Fugaku’s fate. The Japanese air forces no longer had need of a super long range bomber and demanded more perti­nent aircraft to protect the mainland. As such, all work on the Fugaku was stopped and the plans, calculations and drafts were shelved. Work on the production facility was halted prior to completion and left unfinished. With the Japanese surrender, all documentation
for the Fugaku was to be destroyed to prevent the information being handed over to the Allies. Papers on the Fugaku that survive to this day, including a number of drafts for var­ious Project Z/Fugaku proposals, were mis­laid or kept for safe-keeping by individuals. Since the war it has been claimed that the Misawa Air Base would have been used by Fugaku bombers to launch raids against the US. While Misawa was used by the IJA and operational IJA bombers flew from this facil­ity, there has been no definitive evidence to support or refute Misawa being considered as a Fugaku base.

Bombing was not the only mission that was envisioned for the Fugaku and during the Pro­ject Z brainstorming three other concepts arose and later formed part of Chikuhei’s the­sis. The first was an attack design that had 400 Type 97 7.7mm machine guns crammed into the aircraft. The front and the back of the bomber would accommodate 40 machine guns arranged in ten rows. The intention was to rain thousands of rounds of bullets down on to enemy ships with the theory that a swath of destruction 45m (148ft) wide and 10km (6.2 miles) long could be achieved by 15 Fugaku aircraft. Once the decks of these ships were swept of personnel, nine Fugaku bombers, each with twenty 907kg (2,0001b) bombs or torpedoes, would deliver the coup de grace, covering a path 200m (656ft) wide and 1km (0.62 miles) in length with high explosive.

Another version had the Fugaku loaded with 96 Type 99 20mm cannons. The front and the back of the aircraft would contain 12 cannons arranged in eight rows while another 36 cannons were fitted on each side of the aircraft. This particular variant was to target enemy bombers flying missions against Japan and would use hidden bases untouched by the Japanese airfield bombing campaign. By flying over the enemy bomber formation and unleashing a withering fusil­lade of cannon fire, it was speculated that ten
of the cannon equipped Fugaku could bring down 100 bombers, the area covered by the cannons from one plane being 2.5m (8.2ft) and 3km (1.86 miles) long. A system of ground radar stations would give advance warning of the incoming enemy bomber force, allowing time for the Fugaku to inter­cept and destroy the bombers before they reached Japan. This was all very impressive on paper but had it been put into practice the results were likely to have been less than stel­lar, especially when considering the failure of the Mitsubishi G6M1 heavy escort fighter (a G4M converted into a gunship to provide cover for bomber formations). Finally, the Fugaku was considered as a transport which would have provided a significant heavy lift capability. It was estimated that one Fugaku transport would be able to carry 300 soldiers with full equipment, about equal to one infantry rifle company with a heavy weapon platoon. Chikuhei envisioned a grand scheme of a raid against America where four hundred transports would deposit 120,000 men (equivalent to a Japanese Army, which equates to a US and British Corps) on US soil to take over the Seattle-Tacoma airport located in Washington. After landing the troops would move overland to attack and destroy Boeing’s B-29 producing Renton Fac­tory in Renton before returning to Japan.

There is no evidence to suggest any of these concepts made it to the final Fugaku designs. However, if any of the three ideas were supported, a transport may have topped the list for possible consideration given the late war need for aircraft capable of bringing raw materials into Japan to feed the war industry that was slowly being starved. As a note, although the designations G10N and G1 ON 1 have been used in print for this aircraft for many years, there has been no confirma­tion in historical sources that confirms this was the case.

In the spring of 1938, the UN issued a 13-shi specification for a long range fighter. This came about as a result of combat experience in China that showed that Japanese fighters did not have the range to escort bombers on missions deep into Chinese territory, the result of which were high losses. What Naka­jima produced to answer the specification would have been a complete failure had it not been for one redeeming feature.

The 13-shi specification was a very strict one with a number of very demanding crite­ria. Nakajima’s Katsuji Nakamura would pro­duce the initial prototype. It was an aerodynamically clean З-seat monoplane with low mounted wings. Each wing housed a Nakajima Sakae radial, developing 1,130hp. However, one wing was fitted with a Sakae 21 engine, the other with the Sakae 22, and their propellers rotated in opposite directions to reduce torque. To complement the nose armament, twin remote controlled barbettes, each with two 7.7mm Type 97 machine guns, were placed behind the pilot’s cockpit. Des­ignated the J1N1, the first two prototypes were delivered and put under test. A myriad of problems were noted – the plane was over­weight, the novel propeller arrangement caused numerous difficulties, the hydraulic system was too complex, the barbettes were too difficult to aim and the entire arrange­ment was too heavy. To top it all off, manoeu­vrability was poor and all the J1N1 had going for it was its range.

Rejected as a heavy fighter, the JIN was given new lease of life as a reconnaissance aircraft. Nakajima stripped the aeroplane of its weapons and the barbettes, cut the fuel capacity (which, in part, was made up by using drop tanks) and replaced the Sakae 22 engine with another Sakae 21 powerplant. The armament was a single, rear firing 12.7mm Type 2 machine gun to be was used by the radio operator. Now called the J1 Nl-C, following successful trials the aircraft received approval and entered service with reconnaissance units from August 1942. On encountering it in combat, the Allies code – named the plane Irving, thinking it was a fighter. The 1JN renamed the plane J1N1-R, equipping some examples with a turret mounting a 20mm Type 99 Model 1 cannon.

In early 1943, Commander Yasuna Kozono, who led the 251st Koktttai operating from Vunakanau Airfield in Rabaul, Papua New Guinea, believed that the J1N1 – C would make an excellent night fighter. Mechanics replaced the observer’s station and installed two 20mm Type 99 cannons that fired upward and forward at a 30° angle and two additional cannons firing downward and for­ward at a similar angle. Called the J1N1 – C Kai, the field modification proved a success and with that success, the UN became interested.

In short order, Nakajima was instructed by the UN to produce a dedicated night fighter version of the J1 N. By August 1943, the assem­bly of the first model, the J1N1-S Gekko (meaning ‘Moonlight’), had begun at Naka­jima’s Koizumi plant. The main changes saw the glazing over the crew compartment reduced and the step removed. The ring exhaust collector was also removed and the engines used individual exhaust stacks. In addition, it was realised that the downward firing cannons were ineffective and in the JINl-Sa were removed. Both the J1N1-S and JINl-Sa were sometimes fitted with a centi- metric radar in the front of the aircraft, the external antenna for the set being situated on the tip of the nose. Others had a searchlight in the nose while a number lacked the radar and searchlight to be replaced by a single for­ward-firing 20mm Type 99 cannon.

In combat, the Gekko proved satisfactory against the Consolidated B-24 Liberator, but against the faster Boeing B-29 Superfortress was hard pressed to make a single attack. Therefore, it should not be surprising that the JIN was considered as a candidate to be equipped with two turbojets. Successful as a reconnaissance platform as well as a night fighter, replacing the radial engines with tur­bojets would have provided the JIN with a superior speed that would have served it well in either role. A contemporary illustration of the turbojet equipped J1N shows the fuselage of a J1N1 – Sa. The illustration lacks the upward firing cannon and radar which suggests it was equipped with the nose mounted cannon as its armament. Perhaps it may have worked in conjunction with radar and/or searchlight equipped J1N1 -S and J1N1 – Sa during combat missions, or it may have been considered as a fast special attacker fitted with two 551 lb bombs (as surviving JIN aircraft were at the end of the war). The wings seem to have been unaltered outside of the required mod­ifications to fit the nacelles for the turbojets. As to what jet engines were to be introduced is not known. The Kugisho Ne20 was cer­tainly a candidate as was the Nakajima Ne 230. The adaptation of the J1N to jet power would likely have been an easier task than that faced by Kugisho in adapting the P1Y1 Ginga into the turbojet bomber Tenga.

Exactly when the proposal to modify the JIN to a turbojet aircraft was made is unknown. What is known is that it did not progress past the drafting board.

Nakajima JIN Gekko – data Contemporaries Curtiss XP-87 Blackhawk (US), Messerschmitt P.1099 (Germany) No exact specifications are known for the turbojet powered J1 N. The specifications given below are for the J1N1-S. Type Night Fighter Crew Two Powerplant Two Nakajima NK1F Sakae 2114-cylinder, air-cooled radial, each rated at 1,130hp for take-off, 1,1 OOhp at 2,850m (9,350ft) and 980hp at 6,000m (19,685ft), driving a three-bladed, constant speed metal propeller Dimensions Span 16.97m 55.7ft Length 12.74m 41.8ft Height 4.54m 14.9ft Wing area 40.00nT 430.5ft2 Wing loading 175.27kg/m! 35.9 lb/ft2 Power loading 3.62kg/hp 8 Ib/hp Weights Empty 4,840kg 10,6701b Loaded 7,010kg 15,4541b Maximum 8,184kg 18,0431b Performance Speed 507km/h 315mph at 5,840m at 19,160ft Cruise speed 333km/h 207mph at 4,000m at 13,125ft Climb 9 min 35 sec to 5,000m (16,405ft) Range 2,544km 1,581 miles Max range 3,779km 2,348 miles Ceiling 9,330m 30,610fl Armament Two upward firing 20mm Type 99 cannons and two downward firing 20mm Type 99 cannons installed in the fuselage Deployment None. The turbojet powered JIN remained a paper project.

Even though the genesis of the turbojet began long before World War 2, it would take the war to accelerate the development of this new powerplant to the point that by the close of hos­tilities jet aircraft had been blooded in battle. Germany can, by some, be considered the leader in turbojet technology during the war, but the US and Britain were not far behind. Japan, too, was not idle in producing its own turbojet but it would take German knowledge to give their industries a boost. One such results was was an historic aircraft in the annals of Japanese aviation history: the Naka­jima Kitsuka.

Because the Kitsuka (which in Japanese means ‘Wild Orange Blossom’) was probably the most important Japanese aircraft to use a jet engine as its powerplant, it seems apt to provide a general overview of Japanese turbo­jet development in this section. The first axial – flow turbojet was patented in 1921 by Frenchman Maxime Guillaume. However, the technology of his day was not enough to realise a working model, in 1930, Englishman Frank Whittle designed a turbojet using a centrifugal
compressor and, despite relatively little inter­est being shown in it, he patented his concept. In 1933, German Hans von Ohain designed a turbojet similar to Whittle’s but it would not be until 1936 that Ernst Heinkel took an interest in the engine and hired von Ohain to continue his work. By March 1937, this resulted in the Heinkel HeS 1, the first German jet engine although in fact a hydrogen demonstrator. The following month Whittle tested his first jet engine, the WU or Whittle Unit.

Around this time, Rear Admiral Koichi Hana – jima became aware of Whittle’s work as well as that of Secondo Campini, an Italian who began work on a thermojet and an aircraft to use it: the Campini Caproni N. l in 1934. This rekindled his interest in jet propulsion and using his position as head of the engine division of the Dai-Ichi Kai – gun Koku Gijutsu-sho, saw to it that studies were conducted in such engines. Hanajima reached out to the Tokyo Imperial University and Mit­subishi Jukogyo K. K. and together all manner of rocket and jet engines were investigated such as ramjets. To Hanajima’s disappointment, little official interest was generated from the results.

1938 saw German firm BMW begin their research into turbojets and the Heinkel He 178 VI prototype was built to test the HeS 3 turbo­jet that was being developed from the earlier HeS 1. In late 1938, Messerschmitt started work on what would become the world’s first jet fighter to enter squadron service, the Me 262. In Japan, and despite the lack of interest being shown in jet propulsion, Captain Tokiyasu Tanegashima was appointed as the head of the Engine Test and Field Support Shop of KQgisho. He was issued with a meager sum to fund jet engine research although, with the assistance of Professor Fukusaburo Numachi, he would initially focus his efforts on turboprops. Both men were able to source the Ishikawajima – Shibaura Turbine Company and Ebara Seizo K. K. to help build a number of test engines that used compressors and gas turbines, but these labours did not bear fruit.

By 1939, BMW had tested its first axial-flow turbojet design and on 27 August of that year the He 178 VI made its first flight, the first tur­bojet powered aircraft to fly. In February 1940, the British Air Ministry ordered two examples

of the E.28/39 research aircraft from the Gloster Aircraft Company to serve as testbed aircraft for Whittle’s engines. 1940 also saw the Italian N. 1 fly for the first time and Heinkel began glid­ing tests of the He 280 jet fighter prototype as it waited for its two HeS 8 turbojets now under development (the He 280 did not enter pro­duction). November would see Junkers test the Jumo 004 turbojet and Gloster’s jet fighter proposal, the Meteor, was ordered in February

1941. Also in November, Lockheed com­menced work on the L-1000 axial-flow turbo­jet, the first American jet. Finally, in December, Whittle’s W.1X turbojet, a flight ready engine, was tested for the first time.

Japan though, was not idle in 1940. Early in the year, Tanegashima, with the help of the Mit­sui Seiki Kogyo K. K., created a free piston com­pressor for a gas turbine based on a Junkers design, but it was not a success as a means for aircraft propulsion. Another attempt was tried by a different department. Under the leader­ship of Lieutenant Commander Osamu Nagano, head of the Kugisho aircraft engine division, and Masanori Miyata, who led the Kugisho electric parts section, built a tiny free piston compressor gas turbine, generating one tenth of a horsepower at 12,000rpm that drove a magneto that lit a lamp. Despite this measure of success, apathy on the part of the UN con­tinued to stymie progress. Tanegashima soon realised that the Japanese industry was not capable of constructing a free piston engine and switched his studies to axial flow jets.

On 15 May 1941, the Gloster E.28/39 flew for the first time, but previously in April, Heinkel’s He 280 VI had flown under jet power on its maiden flight, the first jet fighter to fly. 1942 saw the Junkers Jumo 004 under test while BMW focused efforts on the BMW 003 Sturm. Heinkel was instructed to concentrate on developing the HeS 011, a turbojet that was to power the second generation of German jets. On 18 July, the Messerschmitt Me 262 flew under turbojet power, becoming the second jet fighter to fly, and on 2 October, the American Bell XP-59 Airacomet jet fighter made its maiden flight. By this time, Japanese engineers and scientists had learned of the flight of the He 178 as proof that an aircraft powered by a jet engine was feasible. This was just the boost the flagging Japanese jet engine research desperately needed.

As a result two different paths were taken with renewed vigour. The first employed the principle of the thermojet (as used by Secondo Campini) and was called the Tsu-11. While this engine was to be selected for use in the Kugisho Oka Model 22, it was found to be unsuited as a powerplant for a jet aircraft. The second route, that of a pure jet engine, was pursued further. Kugisho’s Vice Admiral Misao

Wada was the man who oversaw the develop­ment of a turbojet and the first result was the TR-10. This had a single stage, centrifugal com­pressor with a single stage turbine and was, in essence, built by adapting a turbosuper­charger. The engine was constructed by Ebara Seizo K. K. When the TR-10 was first tested in the summer of 1943 its performance did not meet expectations. The TR-10 was renamed the NelO and the engine was further devel­oped by adding four axial stages in front of the engine inlet. This reduced the load on the cen­trifugal compressor, lowered the engine RPM and produced more thrust. The revised jet engine was designated the Ne 12. The problem with the Ne 12, however, was its great weight and so steps were taken to lighten the engine, which resulted in the Ne 12B.

1944 was an ominous year for Japan. When the Mariana Islands of Saipan and Tinian were wrestled from the Japanese by US forces in July and August, Japan found herself well within striking distance of the Boeing B-29 Super­fortresses. Prior to this, B-29 raids had to fly from remote bases in China and India and so the bombing of Japanese targets was relatively rare. Staging from Saipan and Tinian, B-29s were far closer, could be more active and the Japanese were only too aware of this. In addi­tion, it was surmised that it would only be a matter of time before the main Japanese islands were targeted for invasion. In August 1944, the Kaigun Koku Hombu called for a meeting to discuss changes in air strategy to combat the air and land threat as well as to consider the aircraft that would be used. The Kaigun Koku Hombu invited aircraft designers from both Nakajima and Kawanishi to attend and the outcome of this meeting was the pro­posal for three classes of aircraft termed Kokoku Heiki (one literal translation being ‘Empire Weapon’). The first class, or Kokoku Heiki No. l, was the adaptation of current air­craft to accept a 800kg (1,7601b) bomb with which their pilots would undertake shimpQ missions and target enemy invasion ships. If the bomb overloaded the carrying capacity of the aircraft, then RATO (Rocket Assisted Take – Off) units would be used to get them airborne. Kokoku Heiki No.3 was to be a conventional, radial engine aircraft designed by Kawanishi as the TokkO-ki, which would be used for shimpii missions, but this project was soon abandoned (perhaps because the UN was to build the sim­ilar Nakajima Ki-115 as the Showa Тока). It would be Kokoku Heiki No.2 which provided the seed for the Nakajima Kitsuka. This ‘Empire Weapon’ was to be an aircraft that used the Tsu-11 and, when available, the Ne 12 turbojet.

However, three months prior to the meeting, efforts were underway to obtain the Me 262 from Germany. In May 1944, the Japanese negotiated for the manufacturing rights to the Me 262 and the Germans initially agreed to the release. However, the deal was not concluded due to the large number of modifications that the design was found to require after its flight testing. It was not until July 1944 that orders were given to provide the Japanese with blue­prints of the Me 262 fighter and the Junkers Jumo 004 and BMW 003 turbojets.

On 22 July 1944, Reichsmarschall Hermann Goring authorised the licensing of the Me 262 to Japan and the delivery of one sample air­craft. However, the Japanese submarine 1-29 had left Lorient, France, on 16 April with a sam­ple Junkers Jumo 004 turbojet and plans for the Me 262 and BMW 003 turbojet among its cargo. Also aboard the submarine was Technical Commander Eiichi Iwaya who carried on his person a portion of the documentation on the German fighter and turbojets. By 14 July, the 1-29 had arrived in Singapore. Iwaya, seeking to reach Japan as soon as possible, disembarked from 1-29 and took only a portion of the German documentation. From Singapore, Iwaya flew to Tokyo. On 26 July, Allied code intercepts pin­pointed the location of 1-29 and the USS Saw­fish sent her to the bottom near the Balintang Channel in the Luzon Strait, taking the precious cargo with her.

When Iwaya arrived in Japan, all he pos­sessed of the German files with regards to the Me 262 and turbojets was a single copy of a cross-section of the BMW 003A turbojet. The subsequent news of the loss of 1-29 was a crushing blow, but not a fatal one by any means. In studying the BMW 003A document, the Japanese found it to be of a similar design to the Ne 12 but instead of the centrifugal com­pressor the German engine used an eight stage axial-flow compressor. It was adjudged that this method was superior to the Ne 12 and as such, efforts should be concentrated on build­ing the Japanese equivalent to the BMW 003A. Despite the decision against it, work on the Ne 12B continued. Four companies were involved in the development of the new turbo­jet. Each was to be provided with a copy of the BMW 003A cross-section and other available data and to build their own versions. Ishikawa – jima-Shibaura Turbine Company was to develop the Ne 130, Nakajima Hikoki K. K. the Ne 230, Mitsubishi Jukogyo K. K. the Ne 330, and Kugisho would move forwards with the Ne 20.

Following the August conference with the Kaigun Koku Hombu, Ken’ichi Matsumura, chief designer for Nakajima and with the assis­tance of Kazuo Ono, produced a number of concept drawings for the Kokoku Heiki No.2. Within Nakajima, the new aircraft was given the codename Maru-Ten. On 14 September 1944, UN representatives met with Nakajima at their Koizumi plant to discuss the concepts which had been put forward. The design that stood out was based on a description of the Me 262 as provided by Technical Commander Eiichi Iwaya who, while in Germany, was able to view and study the German jet. Thus, Mat – sumura’s drawing bore an outward resem­blance to the Me 262. After reviewing the concept, the design was approved as the Kokoku Heiki No.2. In keeping with the shimpu mission of the aircraft, the initial design had no landing gear and was to be launched from cat­apult ramps, boosted with RATO units. The cal­culated range was a mere 204km (127 miles) due to the designated engine, the Ne 12, which burned fuel at a rapid rate. At sea level the esti­mated speed was 639km/h (397mph). A single bomb fixed to the aircraft was the only arma­ment. Another feature was the inclusion of folding wings to allow the aircraft to be hidden in caves and tunnels and protected from bombing attacks.

On 8 October, Kugisho ordered Kazuo Yoshida, plant director for Nakajima, to have a wooden mock-up of the aircraft completed and ready for inspection by the end of the month. In addition Nakajima was told to have the initial structural plans finished by the same date. This was ordered so that production of the aircraft could begin without delay. Unfortu­nately, delays would be a major problem. The UN promised that the Ne 12 would be ready for testing by November 1944 and in short order thereafter, production engines would be avail­able. Based on this assumption, Nakajima was to construct thirty aeroplanes by the end of December 1944. Because of the rush to pro­duce the aircraft, a myriad of problems arose with the design which necessitated changes. A major issue was the lack of critical war materi­als which required the use of substitutes and brought additional delays. To compound the problem, Nakajima was concerned that the Ne 12B would not be ready despite the UN’s promises.

Meanwhile, Kugisho proceeded with the Ne 20. The engineers were forced to use alloys which were not to the standards of the German engine and would be a source of problems dur­ing testing. The design of the Ne 20 was smaller than the BMW 003A but it retained the com­bustion chamber shape of the German engine. While it used the same size of burner as the BMW 003A, it only used twelve instead of six­teen due to the smaller size. Kugisho would draft and refine the design of the Ne 20 through December.

On 9 December 1944, the UN called a meet­ing to discuss the progress and outlook of the Kokoku Heiki No.2. Based on the problems Nakajima were having with the aircraft, not to mention the doubts about the Ne 12, the pro­duction schedule was revised. Nakajima were requested to produce the first prototype by February 1945 for use in static testing. It was also during this meeting that the aircraft’s spec­ifications underwent a revision. Instead of a fixed bomb, the bomb could now be released by the pilot. The role of the aircraft was also changed. No longer was it to be used for a shimpu mission but instead for close air sup­port, the aircraft acting as a fast attack bomber. As a consequence of these changes, the design had to incorporate a landing gear. The UN issued its specifications for the new jet, which was now called the Kitsuka, and the docu­ments requested:

Span: no more than 5.3m (17.3ft) with the wings folded

Length: no more than 9.5m (31.1ft)

Height: no more than 3.1m (10.1ft)

Powerplant: Two Ne 12 jet engines Maximum Speed: 513km/h (319mph) with 500kg (1,102 lb) bomb Range: 204km (127 miles) with a 500kg (1,1021b) bomb or 278km (173 miles) with a 250kg (551 lb) bomb Landing Speed: 148km/h (92mph)

Take-off Run: 350m (1,148ft) using two 450kg (992 lb) RATO bottles

Manoeuvrability: The aircraft had to be highly manoeuvrable, have a short turn radius and be stable at speed to facilitate target tracking Protection: Shatter proof glass for the canopy. Front windscreen to have 70mm of bullet proof glass. 12mm of steel armour plate below and behind the pilot. Fuel tanks to be 22mm sandwich types

Basic Instrumentation: Tachometer, altimeter, artificial horizon, airspeed indicator, Model 0 Type 1 flux gate compass, fuel pressure gauge, oil pressure gauge, oil temperature gauge, tail pipe temperature gauge and a pitot tube electric heater

Basic Equipment: Type 0 parachute, automatic fire extinguisher, Type 3 dry battery, Type 3 radio receiver, Type 1 life raft and a reserve weight of 30kg (66.1 lb)

1945 would open with more misfortune for the Japanese war machine. Japanese troops were pushed out of Burma from 5 January and B-29s would bomb Tokyo the next day. Two days ear­lier, Matsumura and Ono, along with others involved in the Kitsuka project, discussed the possibility of using the Ne 20 turbojet in place of the Ne 12. In the debate, some suggested that the Ne 20 was not as far in development than the Ne 12 and would delay progress if used. On the other hand, some argued that the Nel2 was not achieving significant results. In the end, the consensus was that the Ne 12 should remain as the powerplant only because it was projected to be ready before the Ne 20.

On 28 January 1945, the wooden mock-up of the Kitsuka was finally ready for inspection at Nakajima’s Koizumi plant. Vice Admiral Misao Wada and his staff visited the plant and inspected the mock-up with both Matsumura and Ono in attendance. It was made clear to the Kugisho inspectors that the Kitsuka was a very simple aircraft that could be constructed in 7,500 man-hours. By comparison, it took 15,000 man-hours to build a Mitsubishi A6M Reisen. Following the inspection, Nakajima was told to make two slight adjustments to the Kitsuka. The first involved the windscreen. Originally, the front windscreen was rounded but now it was desired that it should be flat panelled. This change may have been sug­gested to allow for the future installation of a reflector gun sight because such a sight requires flat panels to avoid sighting problems due to canopy distortion. The second alteration was to make the canopy slide to the rear instead of opening to the side. At the conclu­sion of the meeting, Nakajima was told to cease all work on the Nakajima J5N1 Tenrai and the company was also informed that they could expect the Nakajima G8N1 Renzan to be terminated as well. These changes in produc­tion and development were done to speed the coming production of the Kitsuka. The close of January also saw the final design draft of the Ne20 completed and almost immediately work began to build the first engine. Kugisho’s Aero Engine Division provided 400 machine tools and engineers and labourers began to toil day and night to realise the Ne 20.

February 1945 opened with the Japanese naval docks in Singapore targeted and destroyed by B-29 bombers along with contin­ued fighting in the Philippines. A second inspection of the Kitsuka was called for on 10 February. Present at the inspection, among the other engineers and Kugisho personnel, were Technical Commander Iwaya and the man who was destined to fly the Kitsuka, Lieutenant Commander Susumu Takaoka. The Kitsuka was given final approval and production was to commence at once, even before the Kitsuka had been flight tested. The first five Kitsuka air­craft, No. l through No.5, were to serve as pro­totypes and none would be fitted with armour plating or self-sealing fuel tanks. In addition the first two aircraft would not to be equipped with the bomb carrying apparatus. February would also see the Ne 12B tested for the first time.

Unfortunately for the Kitsuka, US bombing ensured that production did not go smoothly. Due to the ever increasing number of strikes against the industrial centres of Japan, it was felt that it was only a matter of time before the Nakajima Koizumi plant would attract the attention of US bombers. Therefore, on 17 Feb­ruary, engineering staff for the Kitsuka was moved to Sano in Tochigi Prefecture. Despite the move, a sizable portion of the Kitsuka com­ponent construction remained at Koizumi while the wings, tail assembly and the centre and aft portion of the fuselage were con­structed by Kugisho in Yokosuka. In the face of further bombing attacks, production was dis­persed among silkworm factories and build­ings in Gunma Prefecture (northwest of Tokyo).

March arrived in a blaze of smoke and fire as the US ramped up their incendiary bomb cam­paign against Japan’s cities. Tokyo and Nagoya were particular targets, the burning cities light­ing the night sky. On March 26, the first Ne 20 engine was successfully test run from a cave set into a cliff in Yokosuka. With the success of the Ne 20, the Kitsuka engineering team began to seriously consider replacing the Ne 12B with the Ne 20. It was clear that the Ne 20 outper­formed the Ne 12B and, based on the higher thrust potential, it was decided that the Kitsuka should use the Ne 20 even if it meant a longer delay while the engine became available. Although the current Kitsuka production did not yet involve the engine mountings, a revi­sion of the aircraft design plans was required to accommodate the Ne20. By March 31, these revisions were complete and the Kitsuka pro­gram entered a stage of finality.

With the revised Kitsuka, some of the speci­fications were adjusted as follows:

Maximum Speed: 620km/h (385mph) with a 500kg (1,1021b) bomb at sea level Range: 351km (218 miles), at sea level, at full power

Take-off Run: 500m (1,640ft) with two 450kg (992 lb) RATO bottles Landing Speed: 92km/h (57mph)

Bomb Load: 500kg (1,102 lb) as normal with the ability to carry a 800kg (1,763 lb) bomb; a Type 3 rack would be used for the larger bomb Protection: Reduce the bullet proof glass thickness to 50mm and add 12mm of armour to the front of the cockpit, while the fuel tanks would incorporate an automatic fire suppression system

Engineers working on the Ne20 found that, although the initial test of the engine was a suc­cess, there were many issues to solve. At first, the blades were prone to cracking but this was soon overcome. An electric starter was fitted into the compressor spinner that could spin the engine at 2,250rpm; the engine would reach maximum RPM within 10-15 seconds of engine start. Gasoline was used to start the engine and once running the fuel was switched to a pine root distillate using 20-30 per cent gasoline. What was becoming a problem was how to position the tail cone. Lieutenant Commander Osamu Nagano and his team, along with Cap­tain Tokiyasu Tanegashima, laboured to refine the Ne 20. The worsening bombing situation saw the Ne 20 team moving to Hadano in Kanagawa Prefecture, a three hour drive from Yokosuka.

Set up in warehouses belonging to a tobacco factory, the Ne 20 group comprised 10 officers and 200 men. Here, two bench testing stations were created and Ne 20 devel­opment and testing continued. The process revealed numerous flaws. At one stage the pressure of the axial-flow compressor was found to be too low. Nagano came to the con­clusion that the camber of the stators was not correct and so he took them out, bent them on an anvil and then reinstalled them. These were tested in the second Ne 20 to be built. Yet another difficulty arose with the thrust bearings on the compressor which was burn­ing out very quickly. Nagano solved the prob­lem by revising the bearings and bearing rings. One problem that reappeared was blade cracking. The blades were made from manganese-chromium-vanadium steel and not the more suitable nickel alloy. These blades were then welded to the disk and, as such, the blades did not have the strength to withstand the operating stresses of the motor. After one to two hours of operation, cracks would appeare on the blade roots at the point where they connected to the disk. The solu­tion was to thicken the blades but this low­ered the efficiency of the engine. However, the Ne 20 was able to run for four or five hours before cracks appeared and while the engine could have run longer, there was no guaran­tee when blade failure would occur. With these improved results, work began to pro­duce a small number of engines.

25 April 1945 would see the first Kitsuka fuse­lage completed. This was then subjected to stress and load testing which began on 20 May, but with the stipulation that the fuselage was not to be damaged during tests. Nakajima was scheduled to produce 24 Kitsuka aircraft by June 1945 and with the availability of six Ne 20 engines. On the surface, the Kitsuka project looked to be moving along. The reality was a far different story.

On 13 June, Vice Admiral Wada held a meet­ing to discuss the Kitsuka. Wada addressed a number of issues that were becoming prob­lematic. Nakajima’s G8N1 Renzen program had to be stopped in order to free up produc­tion capacity for the Kitsuka as both a special attack aircraft and an interceptor. More trou­bling was that unless the stock of aluminium was conserved the supply would be exhausted by September 1945. At best, even with conser­vation, by the close of 1945 there would be no more aluminium available. As a result, only steel and wood would be left and to use such materials would, again, have caused a revision to the Kitsuka design. The final blow was that high grade aviation fuels would only be avail­able for the Homare series of radial engines. All other engines, including the Ne 20, would have to make do with poorer quality fuel. This, cou­pled with defeat after defeat for the Japanese military, cast a very serious cloud over the Kit­suka project and some no longer saw value in continuing with the aircraft. Others however, had a strong desire to see the Kitsuka taken to completion because it would put Japan into the jet age.

On 25 June 1945, the first Kitsuka was com­pleted but without its engines. Although exter­nally the Kitsuka bore a resemblance to the Me 262, that was as far as it went. The wings of the Kitsuka had a total of 13° sweepback, the centreline of the wings being at 9°. Wing tip slots eliminated the tip stall discovered during wind tunnel testing and split flaps and droop ailerons were fitted to compensate for the heavy wing loading. Nakajima К series airfoils were used – а К 125 airfoil at the wing root and a К 309 airfoil at the wing tip. The wings were

Interceptor initial concepts – data The specifications in parenthesis refer to the modified wing variant. Type Interceptor Crew One Powerplant Two Kugisho Ne 20 axial-flow turbojets, each developing 490kg (1,0801b) of thrust Dimensions Span 10.00m 32.8ft Length 9.23m 30.3ft Height 3.04m 10ft Wing area 13.19m! 142ft2 (modified) 14.51m2 156.2ft2 Weights Empty 3,920kg 8,642.11b (modified) 2,980kg 6,569.71b Loaded 4,152kg 9,153.51b Useful load (modified) 945kg 2,083.31b Fuel capacity 725 litres 191.5 gallons with drop tanks 1,450 litres 383 gals Performance (estimated) Max speed 698km/h 434mph at 6,000m at 19,68511 684km/h 425mph (modified) at 6,000m at 19,68511 Range 608km 378 miles at 6,000m at 19,68511 594km 369 miles (modified) at 6,000m at 19,685ft Service ceiling 12,100m 39,698ft (modified) 12,300m 40,354ft Armament One Type 5 30mm cannon with 50 rounds of ammunition

PHOTOGRAPHS BY TIM HORTMAN

of double spar construction with nine main support ribs, all covered with steel and duralu­min skinning. Mitsubishi A6M Reisen flap hinges were used on the trailing edge flaps and the wing tips were fabricated from wood and steel sheeting. The outer wing folded upwards. The Kitsuka had a slight gull wing form thanks to 5° dihedral of the centre span and 2° dihedral of the outer wing. All control surfaces were fab­ric covered. The fuselage had a slight triangu­lar shape, being composed of three sections (nose, centre section and aft). The centre sec­tion had the centre wing span built into it and much of this and the other two sections were constructed from sheet steel due to the unavailability of duralumin in quantity. Twenty – four bulkheads were contained within the complete fuselage with two bulkheads coming together where each section met, which were then bolted together to complete the fuselage. Two fuel tanks were fitted, one in front of and the other behind the cockpit. The tail of the Kit­suka was fairly conventional and the aft fuse­lage line was kept high so that the stabiliser would not be effected by the jet efflux. For the tricycle landing gear, the main gear (to include the brake system) from a Mitsubishi A6M Reisen was modified to suit the Kitsuka and the 600mm x 172mm-sized wheels retracted into the wing. The 400mm x 140mm-sized nose wheel was taken from the tail wheel of a Kugishd P1Y Gingaand it retracted into the rear of the nose.

After being assembled the Kitsuka was then broken down, loaded into trucks, and moved to Nakajima’s Koizumi plant where two Ne 20 engines awaited it. By 27 June, the Kitsuka had been put back together and the engines installed, and two days later weight and bal­ance checks had been completed. The Kitsuka was then declared ready for flight testing. On 30 June 30 1945, both Ne 20 engines on the Kit­suka were started and run for a short time. Flight testing could not be conducted at the air­field at Koizumi because the runway was too short and had many approach restrictions. Mis – awa Air Base (Misawa Hikojo), in Aomori Pre­fecture 684km (425 miles) north of Tokyo, was also considered since it had open approaches and was rarely visited by Allied long range fight­ers. However, because of the great distance it was ruled out. Finally, it was settled that the air­field at Kisarazu Air Base (Kisarazu Hikojo) would be the location for the first flight because it was far closer to Yokosuka than Mis­awa. Once more the Kitsuka was disassem­bled, loaded into trucks, and moved to the Kisarazu airfield, adjacent to Tokyo Bay.

On arrival, the Kitsuka was reassembled and made ready for its first flight. Unfortunately, on 14 July, during engine testing, a loose nut was ingested which completely shattered the blades in one of the compressors. The damage to the engine was so extensive that repairs were simply not possible and replacement the only option. This delayed the flight for many days. As the Kitsuka was being repaired, the personnel for the 724 Kokutai, which had been designated a special attack unit and which would fly the Kitsuka in service, had been assembled at Yokosuka after its formation on 1 July 1945. On 15 July, the new unit moved to Misawa Air Base where it began training using Aichi D3A1 and D3A2 carrier bombers (known as Val to the Allies), which had been relegated to the training role.

On 27 July, Lieutenant Wada conducted some successful taxi tests with the Kitsuka. High speed taxi tests, however, were prepared by appointed Kitsuka test pilot Lieutenant Commander Susumu Takaoka. Two days after the initial taxi tests, Takaoka ran the Kitsuka up to 129km/h (80mph) and then applied the brakes to test their effectiveness. He found that their stopping power was not adequate, though he felt the problem was not so severe that flight testing had to be stopped. Ground testing was finally completed on 6 August, the same date that Hiroshima was devastated by the ‘Little Boy’ atomic bomb dropped from the B-29 ‘Enola Gay’. News of this strike soon reached the Kitsuka crews, technicians and engineers.

7 August 1945 would see excellent flying conditions and the Kitsuka was made ready for flight. Weather reports stated a 24km/h (15mph) southwest wind and a crosswind blowing from the right across the 1,692m (5,550ft) length of Runway 20 that pointed towards Tokyo Bay. The Kitsuka was only given a partial fuel load to keep the weight to 3,150kg (6,9451b); this allowed for approximately 16 minutes of flight time. No RATO bottles were fitted so that the take-off characteristics of the aircraft could be assessed. Takaoka climbed into the cockpit and made ready to take-off. On his signal the Ne 20 turbojets were started and he was soon taxiing out to the start of the run­way. Once there, he extended the flaps to 20° and kept the brakes set. So as not to cause a compressor stall, Takaoka slowly eased the engine throttles forward and when both had reached ll. OOOrpm, he released the brakes and the Kitsuka began to roll. Twenty-five sec­onds later and after a run of 725m (2,378ft), the Kitsuka was airborne and went into the history books as the first Japanese jet to fly.

At 610m (2,000ft), Takaoka levelled off. He was instructed to not retract the landing gear nor exceed 314km/h (195mph). As a test pilot he was used to hearing the roar of a conven­tional aircraft engine and used such noise as a means to detect problems. However, Takaoka was not prepared for the whine of the turbojets

Specifications in parenthesis refer to the rail launched version.
Type	Special Attacker
Crew	One
Powerplant	Two KOgisho Ne 20 axial-flow turbojets,
each developing 490kg (1,0801b) of thrust
Dimensions
Span		10.00m	32.8ft
Length		9.23m	30.3ft
Height		3.04m	10ft
Wing area		13.19m!	142ft2
Wing loading	(Rail)	270.00kg/m2	55.31b/ft!
Weights
Empty		2,300kg	5,070.61b
Loaded		3,550kg	7,826.41b
	(Rail)	4,080kg	8,994.81b
Performance (estimated)
Max speed		676km/h	420mph
		at 6,000m	at 19,685ft
		888km/h	552mph
	(Rail)	at 10,000m	at 32,808ft
Landing speed	(Rail)	171km/h	106mph
Range		583km	362 miles
		at 6,000m	at 19,685ft
	(Rail)	814km	506 miles, max
Climb	(Rail)	11 min 50 sec to 6,000m (19,685ft)
Ceiling		10,700m	35,104ft
		12,100m	39,698ft
Armament	One 250kg (551 lb) bomb,	one 500kg (1,1031b)
bomb, or two Type 99 20mm cannons

Trainer Kitsuka –	data
Type Trainer
Crew Two (Student and Instructor)
Powerplant Two KOgisho Ne 20 axial-flow turbojets,
each developing 490kg (1,0801b) of thrust
Dimensions
Span	10.00m	32.8ft
Length	9.23m	30.3ft
Height	3.04m	10ft
Wing area	13.19m!	142ft2
Weights Loaded	4,009kg	8,838.31b
Performance (estimated) Max speed	721 km/h	448mph
	at 6,000m	at 19,685ft
Landing speed	166km/h	103mph
Range	66km at	414 miles
	6,000m	at 19,685ft
Ceiling	12,000m	39,370ft
Service ceiling	10,700m	35,104ft
Armament
Likely to cany the payload as per the Kitsuka

Type Crew	Reconnaissance Two (Pilot and Observer)
Powerplant	Two KOgisho Ne20 axial-flow turbojets,
each developing 490kg (1,0801b) of thrust
Dimensions
Span	10.00m	32.8ft
Length	9.23m	30.3ft
Height	3.04m	10ft
Wing area	13.19m!	142ft2
Weights
Loaded	4,241kg	9,349.81b
Performance (estimated)
Max speed	721 km/h	448mph
	at 6,000m	at 19,685ft
Landing speed	169km/h	105mph
Range	666km	414 miles
	at 6,000m	at 19,685ft
Ceiling	12,000m	39,370ft
Service ceiling	10,700m	35,104ft

Armament None (possibly two Type 5 30mm cannons)

Interceptor definitive version – data Type Interceptor Crew One Powerplant Two Ishikawajima Ne 130 or two Mitsubishi Ne 330 axial-flow turbojets, each developing 900 or 1,300kg (1,9841b or 2,8661b) of thrust respectively Dimensions Span 10.00m 32.811 Length 9.23m 30.3ft Height 3.04m 10ft Wing area 13.19m2 142ft2 Wing loading 302.71kg/m! 62 lb/ft2 Weights Empty 3,060kg 6,746.11b Loaded 4,232kg 9,329.91b Useful load 940kg 2,072.31b Performance (estimated) Max speed 713km/h 443mph (Ne 130) at 6,000m at 19,685ft Landing speed 154km/h 96mph Range 594km 369 miles 792km 492 miles at cruise speed Climb 11 min 18 sec to 6,000m (19,685ft) Ceiling 12,300m 40,354ft Armament Two Type 5 30mm cannons or two Ho-155 30mm cannons (IJA); one 500kg (1,1021b) or 800kg (1,763 lb) bomb (if used as a fighter-bomber)

that told him almost nothing outside of what his instruments reported. He circled Kisarazu airfield, keeping it in sight in case of a failure and because the airspeed kept rising, Takaoka had to constantly throttle back to keep from exceeding the gear down speed limit. A brief test of the control sensitivity showed that the rudder was stiff, the ailerons were heavy but were working and the elevators were overly responsive. When his flight time was up, Takaoka was wary of how he would land. He did not want to drop the turbojets to below 6,000rpm since that risked a flameout from which he would likely not recover in time. Therefore, he chose a long, shallow drop, low­ered his flaps 40° and brought the turbojets down to 7,000rpm. On touchdown, he only needed moderate braking to bring the Kitsuka to a stop using only a little under 61 Om (2,000ft) of runway. Takaoka brought the Kitsuka back to the ramp amid throngs of cheering men. The total flight time was 11 minutes. In his immedi­ate report on the flight, Takaoka stated he had experienced no problems with the engines and had no recommendations for improving the aircraft. During his debriefing, technicians had removed the cowlings to the Ne 20 turbo­jets and examined each engine. They found no faults and so gave the Kitsuka clearance for another flight, scheduled for 10 August 1945.

For the second flight, more fuel was to be stored and RATO bottles used; this would allow for a longer flight and test the RATO units as boosters. Takaoka would again pilot the Kit­suka. Prior to the flight Takaoka examined the RATO bottles which were fitted to the under­side of the fuselage and found fault with the angle at which they were set. However, to adjust them would have taken too much time and so instead of 800kg (1,7631b) of thrust, the bottles were reduced to 400kg (881 lb) each.

On the day of the second flight, Allied air power was highly active and any flight attempt was bound to be spotted putting the Kitsuka at risk. Consequently, it was decided to wait until the following day on 10 August. However, it would be remembered for the drafting of the Imperial Rescript on the Termination of the War by the Japanese cabinet at the behest of Emperor Hirohito, though the populace had no knowledge of this.

11 August 1945 shared a similar weather pat­tern to the day the Kitsuka had first flown. The difference was that several UN and IJA officials of high rank had arrived to witness the second flight. Once more Takaoka climbed into the cockpit, signalled for engine start and taxied out to the runway. As before he extended the flaps 20°, and after receiving the signal to take­off, he slowly opened the throttles until the engines had reached 11,000rpm before releas­ing the brakes and the Kitsuka rolled forwards.

At four seconds into the take-off roll, Takaoka activated the RATO units. Immediately, the acceleration caused the nose of the Kitsuka to pop up, the tail slamming onto the runway. Takaoka fought to get the nose down by jam­ming the stick forwards but he received no response from the aircraft’s elevators. The two RATO units burned for a total of nine seconds and during eight of those seconds Takaoka was helpless and unable to correct the nose up condition. One second prior to the units burn­ing out, the elevators finally took effect and the nose came down so hard Takaoka was sure the front tyre had blown when it contacted the runway. Takaoka felt a sense of deceleration as the Kitsuka reached the halfway point on the runway – his speed at that point was 166km/h/l 03mph. A second later, with the feel­ing of deceleration still present, Takaoka decided to abort the take-off and he cut the power to the engines. Unfortunately, the brake issue Takaoka had discovered during high­speed taxi tests now came back to haunt him.

Despite maximum application of the brakes, the Kitsuka showed no signs of slowing and Takaoka was rapidly running out of runway. As he neared one of the taxiways, Takaoka held the left brake in an attempt to make the Kitsuka bring its left wing down into the ground to bleed off speed (known as a ground loop). The Kitsuka’s nose turned slightly but this then put the aircraft on a crash course with a group of hangars and buildings. Takaoka reversed the braking, holding the right brake. The Kitsuka came back around onto the runway and despite Takaoka working the brakes, it was to no avail. The aircraft ran out of tarmac and crossed the 100m (328ft) of grass overrun before the landing gear caught in a drainage ditch and collapsed. The Kitsuka slid along its belly until finally coming to a halt by the edge of the water of Tokyo Bay. The damage to the Kitsuka was extensive. In addition to the man­gled landing gear, the two Ne 20 engines were badly damaged, having been jarred from their mounts but still remaining attached to the wings. Initial assessments suggested that the damage was so severe the Kitsuka could not be repaired. On the positive side, the aircraft did not catch fire and causes of the accident were swiftly looked into. UN Captain Ito, who was present for the flight, was thankful that the Kitsuka did not become airborne with the nose high attitude during the RATO burn. Had that happened and once the RATO bottles cut out, the Kitsuka would have most likely crashed into the ground. A motion picture camera cap­tured the flight and the film developed to see if it could shed any light on the crash.

On 15 August, the film of the ill-fated flight was studied but proved inconclusive as to whether or not the Kitsuka was airborne once

the RATO bottles were exhauasted, as was suspected. This would have explained the heavy impact of the front landing gear on the runway and the sense of deceleration experi­enced by Takaoka. In any case, the Kitsuka would never fly again for at 12.00pm the Impe­rial Rescript on the Termination of the War was broadcast on the radio bringing World War 2 to a conclusion.

The end of the war would see none of the Kitsuka production plans realised. Nakajima, by the close of December 1945, was to have produced 200 Kitsukas. In reality, Nakajima completed only one with a further 22 under construction. The Kyushu Hikoki K. K. was, also by the end of the year, to have turned out 135 Kitsuka aircraft but was only able to begin con­struction of two aircraft, started in July 1945, which remained unfinished by the close of hostilities. A third producer, the Sasebo Naval Arsenal (Sasebo Kaigun Kosho), was sched­uled to have begun production of the Kitsuka in September 1945 with 115 completed by the close of December. The fourth production line was to be at the Kasumigaura Naval Air Arsenal with the commencement of Kitsuka construc­tion scheduled for October 1945; 80 aircraft were to have been completed by the end of December.

A number of variants of the Kitsuka were planned, none of which would see completion come the capitulation. One of these was a two – seat trainer. Given the nature of the Kitsuka, it was appreciated that a trainer would be required to help the conversion of pilots used to conventional piston engined aircraft to the peculiarities of a turbojet powered aircraft. Five of the Kitsuka airframes under production by Nakajima were modified by including a sec­ond cockpit for the instructor. Outside of the inclusion of the additional cockpit, it is unknown exactly what other changes were made in the Kitsuka to accommodate it. If there were a parallel to the German Me 262B-la two-seat trainer, the rear fuel tank would have been removed to make room for the instructor’s cockpit. The German solution to the loss of fuel was to utilise the two front bomb racks for drop tanks. Whether Nakajima considered the use of drop tanks (as the Kit­suka could use them) or simply accepted the reduced endurance for the sake of expediency is not known. The two-seat trainer would be the only variant of the Kitsuka to reach the pro­duction phase.

It was planned that some of the two-seaters were to be modified for reconnaissance roles. The instructor’s cockpit was to be removed and replaced with a crew position for an observer. He was to have a Type 96 Model 3 radio set at his disposal for use in relaying tar­get information to other aircraft. It is unknown

Contemporaries Messerschmitt Me 262A-1 a/U3 and Me 262A-5a (Germany), Messerschmitt Me 262A-2a/U2 (Germany), Messerschmitt Me 262B-la (Germany), Messerschmitt Me 262C-la, Me 262C-2b, and Me262C-3 (Germany)

Type	Attack Bomber
Crew	One
Powerplant	Two Ktigishb Ne 20 axial-flow turbojets,
each developing 490kg (1,0801b) of thrust
Dimensions
Span	10.00m	32.8ft
	5.24m	17.2ft (wings folded)
Length	9.23m	30.3ft
Height	3.04m	10ft
Wing area	13.19m2	142ft2
Wing loading	268.53kg/m2	55 lb/ft2
Power loading	1.6kg/kg	3.7 lb/lbst
Weights
Empty	2,300kg	5,070.61b
Loaded	3,550kg	7,826.41b
Max loaded	4,312kg	9,506.31b
Useful load	1,249kg	2,753.51b
Performance
Max speed	621 km/h	386mph at sea level
	679km/h	422mph
	at 6,000m	at 19,685ft
	695km/h	432mph
	at 10,000m	at 32,808ft
Max speed	509km/h	316mph
	at sea level, with 500kg (1,102 lb) bomb
Take-off speed	148km/h	92mph
	at a weight of 3,950kg (8,708.2 lb)
Landing speed	158km/h	98mph
	at a weight of 2,570kg (5,665.8 lb)
Take-off length	504m	1,653.5ft
	with RATO with zero wind at
	a weight of 4,200m (9,259.4 lb)
	1,363m	4,471.7ft
	without RATO with zero wind at
	a weight of 3,950kg (8,708.21b)
Range	583km	362 miles
	at 6,000m	at 19,685ft
	888km	552 miles
	at 10,000m	at 32,808ft
	203km	126 miles
	with maximum bomb load
	555km	345 miles
	with 551 lb bomb load
	948km	589 miles at cruise speed
Climb	12 min 16 sec to 6,000m (19,685ft)
	32 min 42 sec to 10,000m (32,808ft)
Ceiling	12,000m	39,370ft
Service ceiling	10,700m	35,104ft
Fuel capacity	725 litres	191.5 gallons
	1,450 litres	383 gals with drop tanks
Armament
One 500kg (1,1021b) or 800 (1,7631b) bomb

Deployment

None. One finished aircraft was built by Nakajima (two if one counts the airframe completed for load testing) with a further 24 in various stages of construction by war’s end.

Survivors

Nakajima Kitsuka (tail number A-103)

With the loss of the only completed Kitsuka following its crash on 11 August 1945, examples captured by the US following the war were from the stocks of incomplete Kitsuka aircraft found in Nakajima and KyQshu’s plants. This particular Kitsuka arrived at NAS Patuxent River and on 18 October 1946 was shipped to San Diego, California. The aircraft eventually found its way back to the Paul. E. Garber facility where it is believed to be the second Kitsuka held in storage there.

Some sources have the serial for this Kitsuka as 7337.

Nakajima Kitsuka (tail number A-104)

Also at NAS Patuxent River with A-103, it was later shipped to NAS Willow Grove in Willow Grove, Pennsylvania on 23 October 1946. Following its arrival, no further trace of the Kitsuka is known.

Nakajima Kitsuka (no tail number assigned)

This Kitsuka was received in the US and appeared on a storage manifest in 1950 being housed at NAS Norfolk in Norfolk, Virginia. In 1960, it was shipped to the Paul E. Garber facility. From 1972 until the facility closed to the public, it was on display hanging from the ceiling (see page 118).

if any cameras were to be fitted but it would not be unreasonable to conclude that the observer would at least have had a hand-held camera.

An interceptor version of the Kitsuka was discussed, as previously mentioned, and a number of general arrangements for it were considered. One of these was the inclusion of a single Type 5 30mm cannon with 50 rounds of ammunition installed in the nose. A second design was to feature enlarged and extended wings incorporating flaps and double-edged leading slots. A more definitive interceptor was to replace the Ne 20 engines with either Ne 130 or Ne 330 turbojets. A second cannon was to be added in the nose. Interestingly, it appears that if the IJA had used the Kitsuka, the Type 5 can­nons would be replaced with two Ho-155 30mm cannons. This may have been a stopgap or fallback if the IJA’s own Ki-201 Karyti failed to materialise. With the heavier weight the structure of the Kitsuka, including the landing gear, would have been strengthened. A fighter – bomber model was envisioned for the defini­tive interceptor by including a fitting for a single 500kg (1,1021b) or 800kg (1,7631b) bomb.

As originally planned, a model of the Kitsuka was proposed for shimpti missions. Similar to the Kitsuka as constructed, this version was to carry either a 500kg (1,1021b) bomb, a 250kg (551 lb) bomb or two Type 99 20mm cannons. With the latter, it could be assumed the can­nons would be used for self-defence and for fir­ing at the target before ramming the aircraft into the victim using any remaining fuel and ammunition as the secondary explosive ele­ment. A variant of this Kitsuka was to utilise a 200m (656ft) launch rail that Kugisho had been designing and which they expected to have ready for testing by September 1945. Using a rocket booster, the Kitsuka would leave the launch rail at 220km/h (137mph) at an acceler­ation of between three to four ‘g’.

In regards to the 724 Kokutai, with the end of the war they would never see their Kitsuka air­craft. It was planned that by November 1945 the unit would have been based near Yokosuka at a site along the Miura Peninsula, west of Tokyo Bay. It was expected that by then the unit would have received sixteen Kitsukas. In addition, the unit was to use one of the handfuls of Kawan – ishi El 5K1 Shiun (meaning ‘Violet Cloud’; code – named Norm by the Allies) reconnaissance floatplanes, which were removed from active service following their disastrous combat debut in 1944. The Shiun, operating from a nearby har­bour, would locate the shipping targets, mark them and then loiter in the area to broadcast radio signals. The Kitsukas would then be rapidly launched and, by means of the radio sig­nals received through the Kuruku system, attack the ships at low level with bombs and ramming tactics. Had the reconnaissance ver­sion of the Kitsuka gone into production, the 724 KokQtai was to receive it as a replacement for the far more vulnerable Shiun.

Finally, with the close of the war, none of the projected turbojet successors to the Ne20 would enter production. One prototype of the Ishikawajima Ne 130 had been completed by June 1945 but testing was unfinished by the time the war ended. Nakajima started devel­opment of the Ne230 in May 1945 and had three under construction by August 1945. How­ever, none of the engines were completed or tested. Mitsubishi was unable to construct a Ne 330 and so it remained on the design board.

A note about the use of the name Kitsuka as opposed to the more commonly used Kikka. Kitsuka is the proper translation of the kanji characters. However, it is pronounced ‘kikka’. Kikka was used in post-war reports as phonet­ically it approximated to Kitsuka and thus has become the accepted name of the aircraft. Neither name is incorrect. Also, some sources use the J9Y1 (or sometimes J9N1) designation for the Kitsuka. While logical for the intercep­tor version of the Kitsuka, there is no evidence in wartime Japanese sources to support the designation. One may also find the designation J8N1 used but this is not supported.