Another Japanese plane that is aaaaalways called a German imitation and a "cheap" and "ugly"* "copy" of the Me262, is the Nakajima "Kikka". But take the time to read more carefuly what the Japanese Wiki has to say about the development of the aircraft based on original Japanese sources, and compare it if you like with the way the English Wikipedia covers the aircraft, based on mostly non-Japanese sources.
Development of the "Kikka" began under the guidance of Navy Technical Lieutenant Nakaguchi Hiroshi (later a professor at Chiba Institute of Technology) of the Naval Technical Arsenal. Engineer Matsumura Kenichi served as chief engineer, assisted by Engineer Ohno Kazuo and others, and design and prototype work commenced. Navy Lieutenant Commander Takaoka Susumu served as the test pilot for the prototype.
In August 1944, Japan had reached an impasse in the development of high-performance piston engines equipped with superchargers for high-altitude flight, and the fuel situation had worsened due to the loss of control of the seas between the Malay Peninsula, a major crude oil production area, and the Japanese mainland. The Navy conceived a land-based attack aircraft equipped with a jet engine—which could operate on low-quality fuel and lubricants, had fewer components than a reciprocating engine, and was simpler yet high-performance—and tentatively named it the “Imperial No. 2 Weapon.” On the 25th of that month, it issued development instructions to Nakajima Aircraft.
Although Japan had been independently developing jet engines alongside Germany, Britain, and Italy, unlike those nations, they had not yet been put into practical use; however, the company had accumulated development experience with models such as the Ne 10 and Ne 10 Kai (230 kg thrust), as well as the Ne 12 (300 kg thrust) and Ne 12B.
There were three initial design proposals:
Proposal 1 was a compound configuration (twin-boom) with engines mounted above and below the fuselage [WOW!];
Proposal 2 was a fuselage-embedded configuration with engines embedded in the sides of the fuselage. Aside from its low-wing configuration, the airframe design of the XP-80A prototype of the P-80 jet fighter, is extremely close to this second proposal;
and Proposal 3 was a wing-mounted configuration, similar to the Messerschmitt Me 262 with engines suspended beneath the main wings. Although the second design was the most advanced, the third design was ultimately adopted after considerations were made to simplify the manufacturing process. It is also said that technical issues related to the low power output of the Ne-20 engine played a role.
Subsequently, Japanese Army and Navy officers and engineers stationed in Germany, decided to obtain technical documentation regarding the Messerschmitt Me 262, and under an agreement between the Germans, who wanted the diesel engines developed by Japan for small boats used on patrol boats, and the Japanese, who wanted the Me 262’s engine for fighter aircraft, the blueprints were transported from the military port of Toulon in France by Japanese and German submarines.
Only one submarine from each side was used for the transport. The German submarine reached Balikpapan in Indonesia, which was under Japanese occupation, around the end of 1944. After landing, the crew exchanged information with Japanese naval officers. Subsequently, the Japanese submarine was sunk by an attack from a U.S. Navy submarine in the Strait of Bashi. It is unclear whether the German submarine returned safely to Germany.
With the sinking of the submarine, nearly all information regarding the Me 262 obtained from Germany was lost, except for a small portion of documents brought back by Lieutenant Commander Iwaya, who had transferred to a Showa/Nakajima L2D "Tabby" transport aircraft in Singapore to return home. Since the crucial blueprints for the airframe and engine core were unavailable, the project ultimately became largely a Japanese independent development.
Initially, the "Kikka" was not equipped with fixed machine guns. It was planned to carry a single 500kg or 800kg bomb under the fuselage, taking off from airfields to perform level bombing and low altitude bombing against enemy ships. According to one account, skip bombing using a bouncing bomb known as the “Type 3 No. 25 No. 8 Bomb” or the “provisionally named Type 4 No. 50 No. 8 Bomb” was also planned (as stated in the draft requirements for the "Kikka" prototype project).
Starting with the second prototype, at the request of the military, the aircraft was equipped with the Type 5 30mm Fixed Machine Gun Model 1, which was comparable to the Me 262’s MK 108 30mm cannon; however, the number of these guns that were to be installed was only two, half that of the Me 262’s four. Furthermore, the ammunition capacity was reduced to 100 rounds for this aircraft, compared to the Me 262’s 360 rounds.
The planned speed was 335knots (approx. 620 km/h) at sea level and 365 knots (approx. 676 km/h) at an altitude of 6,000 m, with a planned range of 200nautical miles (approx. 370 km) at sea level and 300 nautical miles (approx. 555 km) at an altitude of 6,000 m.
At the time of Japan’s defeat, the second "Kikka" prototype was nearly 90% complete at the Koizumi Plant of the former Nakajima Aircraft Co., Ltd. The nose gear had not been installed, and the main landing gear struts and nacelle panels were also missing. With the exception of the windscreen frame, the aircraft was unpainted. The dark-colored section on the outer surface of the forward fuselage is the forward fuel tank, and the silver-colored section extending slightly behind the windscreen to the seventh round frame is made of tinplate. The front view clearly shows the distinctive fuselage cross-section and the gull-wing shaped main wings.
Production
Although its appearance resembled the Me 262, it was smaller (due to the low thrust of the Ne 12B jet engine originally planned for installation, it was necessary to make the airframe smaller and lighter). Unlike the Me 262’s swept-back wings, it adopted tapered wings; due to the circumstances described above, it was in fact almost entirely an original design.
Additionally, the outer sections of the wings could be manually folded upward so that the aircraft could be concealed in an air-raid shelter. The landing gear was of the nose-wheel type; to shorten the development period and streamline parts procurement, the nose wheel utilized the tail wheel from the "Ginga" bomber, while the main wheels used those from the Zero fighter (since there was no time to make modifications on the prototype, the brakes remained those of the Zero. This was the cause of the overrun during testing). To compensate for the engine’s low thrust, two solid-fuel takeoff booster rockets had to be mounted under the wing roots for takeoff with a full load.
Furthermore, it was designed with simplification and reduced production man-hours in mind to suit mass production, allowing it to be manufactured with half the production man-hours required for the Zero.
The aircraft was built under the supervision of Chief Engineer Kenichi Matsuyama at the design department on the third floor of Nakajima Aircraft’s Koizumi Plant in Gunma Prefecture, but the factory was left in ruins following a massive air raid by Boeing B-29s. Although the hangar housing the "Kikka" was damaged, the aircraft itself managed to survive unscathed. Subsequently, to avoid air raids, the aircraft were evacuated from the factory and assembly was carried out in scattered locations, including a farmer’s silkworm rearing shed. The prototype was completed in June 1945, and after passing engine endurance tests, it was transported to Kisarazu Air Base for flight testing, where the engine and airframe were integrated.
Maiden Flight
On August 7, a test flight was conducted. It recorded a speed of 488 km/h. The flight was conducted under light load conditions, carrying only enough low-grade fuel containing pine oil for 16 minutes, and succeeded in flying for 12 minutes; this was the moment when a jet aircraft first took to the skies in Japan. At that time, the "Kikka" was not equipped with takeoff booster rockets, antennas, or nose landing gear covers, and flew with its landing gear extended.
On the 10th, while senior Army and Navy officers were visiting for an inspection, a second flight with a full fuel load was scheduled but canceled due to an air raid; the following 11th was postponed due to bad weather, and the actual flight took place on the 12th. However, during takeoff, the aircraft overshot the runway and came to a stop. The war ended while the aircraft was undergoing repairs. The cause of the failed takeoff was that pilot Takaoka Susumu mistook the decrease in acceleration caused by the end of the takeoff booster rocket’s burn for engine trouble. He attempted to abort the takeoff but was unable to stop the aircraft in time, causing it to veer onto the sandy beach at the end of the runway and damage its landing gear. The aircraft remained in that state until the war ended three days later.
"Special Attack Aircraft"
This aircraft was a special attack aircraft** intended for anti-ship attacks using bombs. Although it was not a special attack aircraft designed exclusively for kamikaze missions from the outset, like the Ohka, some argue that given the name “tachibana flower", which signifies special attack aircraft, and considering the war situation at the time, there was no other military use for it besides kamikaze missions.
Furthermore, the military leadership believed that rather than using expensive reciprocating engines—which required advanced production technology—in kamikaze aircraft and discarding them, they should be conserved as much as possible and used instead in air defense interceptors. They considered that jet engines, which were cheaper and easier to mass-produce than reciprocating engines, would be the optimal choice for kamikaze aircraft, provided the technical challenges could be overcome and mass production achieved.
However, according to a behind-the-scenes account of the Imperial Japanese Navy’s aviation technology development by Lieutenant Sumi Nobuo, who participated in the aircraft’s development at the Naval Air Technical Arsenal at the time, the passage stating, "As the name of the kamikaze aircraft "Kikka" suggests, although it was naturally equipped with a jet engine capable of use as a fighter, it could only be produced as a kamikaze aircraft" this suggests that while the aircraft was expected to fulfill its role as a jet fighter, development approval was granted only nominally as a kamikaze aircraft. This is the reason why the name "Kikka" which includes the kanji character for ”flower" (a symbol of special attack aircraft), was attached to it.
However, Susumu Watanabe, who was in charge of the "Kikka" engine installation, stated, “The "Kikka" was not a kamikaze aircraft; it was a special attack aircraft designed from the outset with the premise of returning”.
*I know that I'm in the minority, but I always found "Kikka's" lines more aesthetically pleasing and airplane-like, than the weird shape of the Me262 with the fuselage looking like a flatfish. But, again, that's just me.
** Although post-war, the wording "special attack" (tokubetsu kogeki) has been exclusively associated with the meaning of "kamikaze, i.e. suicide", actually, this was not always the case. Just as there were "Special Attack Units" that were organized to perform a very specialized mission (skip bombing for example), but one that would not necessarily result in self- destruction, in the same way, there were "Special Attack Aircraft", like the "Kikka". An alternative wording could be "Special Mission Aircraft".
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