Kawasaki "Hien" and the names of Japanese aircraft - Question

Kawasaki Ki-61 Hien”  (Tony) Parked by Parkland Edge. Leave a comment if you know more about the particular aircraft.

An earlier post included the following regarding the Kawasaki Ki-61 “Hien” (Tony):

The prototype designation, the Ki number, was Ki-61. The official designation, Type 3 Fighter, derives from its official adoption in the 2603rd year of the Imperial calendar (1943 (Showa 18)). Although mass production actually began in 1942, the "Type 2" designation was delayed until 1943 to avoid confusion, as there were already the "Type 2 Single-Seat Fighter" (Shoki) and the "Type 2 Twin-Seat Fighter" (Toryu).

Its nickname was “Hien” (Swallow), and unit names and abbreviations included Type 3 Fighter, Rokuichi, Ki no Rokuichi, and Rokuichi Fighter. Within Kawasaki, it was called "Rokuichi", but after the introduction of the Type 2, it came to be called "Ichigata" or "Nigata".

Some sources state that the nickname “Hien” was announced in the latter half of 1944, but it was actually announced in an article in the Asahi Shimbun dated January 16, 1945, reporting on the activities of the 244 Sentai, which was engaged in the air defense of mainland Japan. 

Our friend Alexander Mattiaccio commented and asked:

Very interesting details about the name. If the name “Hien” wasn’t used prior to 1945 (earliest mid to late 1944) isn’t it odd that we refer to it by that name instead of what was common at the time? Why is it that modern publications don’t use the terms given by Kawasaki?

Slightly off topic but I’ve always found it strange that the official plane designations were based on the year of release. Perhaps it’s hindsight blurring my perspective but I would have thought it to be highly likely that two or more planes could be implemented within a Showa year and cause unnecessary confusion. I wonder what drove that and why they stuck with it.

Answer:

Japanese have their own complicated way of doing some things we, gaijin, find easy and natural. They do that because it is what they like to do. Simple as that.

One such example is the date notation in Japan. For those who don’t know, in Japan two calendars are common: the Gregorian or “western” - 2026, and the Imperial - Reiwa 8, which began when the current emperor acceded to the throne. When discussing the ‘30s and ‘40s it is more common the Japanese, especially veterans, to use the Imperial system, i.e. Showa Emperor years. You speak to them about 1944 and you see they can’t figure out what you’re talking about. Say Showa 19, and they immediately understand.

I don’t think anybody knows why the Japanese military adopted the third calendar, the Imperial Year, based on the legendary foundation of Japan by Emperor Jimmu in 660 BCE (the current year 2026 is 2686 in the Imperial Year). But personally I believe it had to do with the gradual militarization of Japan and the constitutional abandonment of any “Western” influences. To give a simple example, the title on the front cover of the earliest issues of one of the first Japanese aviation magazines, is in French “Le Hiko” (did I hear someone say “Le Big Mac”?) and the date is in the Gregorian calendar. A few years later, the title changed to kanji “飛行” (hiko - flight) but on the back cover it’s still the same French “Le Hiko” but with the Imperial calendar. By 1939, there were no non-Japanese letters or words on the front or back cover, and the date changed to Imperial Year.

Here's what the Japanese Wiki has to say about the Imperial Year and the naming/designation of Army and Navy aircraft:

Imperial Japanese Army, aircraft used the Imperial Year system, as seen in the “Type 87 Heavy Bomber” and “Type 87 Light Bomber,” which indicate adoption in the 2587th year of the Imperial Year (1927 AD, the 2nd year of the Showa era). (In reality, both aircraft were officially adopted the following year (1928, the 3rd year of the Showa era). Also, unlike the Navy, when officially adopted in Imperial Year 2600, the number “100” (一〇〇) was used instead of “0” (零), as seen in the Type 100 Heavy Bomber, Type 100 Command Reconnaissance Aircraft, and Type 100 Transport Aircraft. 

From Imperial Year 2601 (AD 1941, Showa 16) onward, only the last digit of the Imperial Year was used, as in the Type 1 Fighter (commonly known as the Hayabusa).

For the Imperial Japanese Navy, the use of the Imperial Year in official designations began slightly later than in the Army. The Imperial Year was first used in the “Type 89 Flying Boat” and “Type 89 Carrier-Based Attack Aircraft,” which indicate adoption in Imperial Year 2589 (AD 1929, Showa 4). However, both aircraft were actually officially adopted in Imperial Year 2592 (AD 1932, Showa 7). Prior to that, model designations based on the era name were used; the “Type 3 Carrier-Based Fighter” indicates adoption in Showa 3 (1928), and the Type 13 Carrier-Based Attack Aircraft indicates adoption in Taisho 13 (1924). 

Furthermore, in the Navy, with the “Type 2 Seaplane Fighter” and “Type 2 Land-Based Reconnaissance Aircraft,” the Navy discontinued using Imperial year-based model designations for aircraft. Instead, it adopted official names consisting of kanji for each aircraft type, such as “Shiden,” “Saiun,” and “Tenzan” (in contrast, the Army's “Hayabusa” and “Hien” were merely nicknames and not official designations). 

In practice, all Japanese WWII veterans were very comfortable using the Imperial Year system for their aircraft, ex. “Type 89 Flying Boat”, because that was the official designation, that was the name printed on the manuals (maintenance of flying) and that was written on most (but not all) stencils on the aircraft. The names (popular “Hien”, or official “Gekko”) were also commonly used but when there wasn’t one (Aichi “Jake”) they used the Imperial Year system. Most often they created their own nicknames, usually an abbreviation of the Imperial Year system, example: the “Reishiki kansokuki” (Type Zero Observation Seaplane, Mitsubishi F1M "Pete") was commonly called “Reikan”.

Even aviation school names were abbreviated. Examples include “Hamako” (Hamamatsu Rikugun Hiko Gakko) and “Kumako” (Kumagaya Rikugun Hiko Gakko).

Another reason for using the Imperial Year system for the aircraft, is that the Japanese (similar to other militaries around the world) were very year-conscious at the time. The year they joined the military, the Class, and the aviation school graduation year were especially important and they associated these with particular aircraft. I guess there was a mental connection: the aircraft types that came out the year I graduated or joined my unit etc.

The aforementioned applies to veterans and the generations that followed directly after the war who engaged with them. Most young Japanese are largely unaware of all the above. They are familiar with the names of certain aircraft, and that's roughly everything. People frequently inquire about my favorite Japanese aircraft from that time period, and whenever I respond with “the KyuNanaSen” (short for “Kyunana-shiki sentoki” Type 97 Fighter, Nakajima Ki-27 “Nate”), they appear utterly confused. Certainly, this does not pertain to individuals who are more adequately informed about the topic.

The Imperial Year system also caused difficulties as Alexander correctly noted. One such example is the Type 97 Carrier Attack Aircraft (Nakajima B5N “Kate”). Since both of the two competing prototypes were adopted, there are two aircraft with this name, one manufactured by Nakajima (B5N) and the other by Mitsubishi (B5M “Mabel”), which have completely different designs. However, the name usually refers to the Nakajima (B5N) version.

As you can read at the top of this piece, the Army found a solution by naming the “Hien” a year later, Type 3, instead of the more correct Type 2. So, there were no extremely strict official rules and some creativity was required.

So, what does all the above mean to us non-Japanese, especially when we interact with Japanese aviation fans or  modellers?

First of all, the vast majority of Japanese have no idea of “kitai” numbers. They don’t understand what aircraft you’re talking about when you say “Ki-61” to them. “Hien” they understand. “SanShikiSen” they understand. “Tony” means Tony Bennett, not an aircraft, if you know what I mean.

“A6M2” is also gibberish to most Japanese. “Zero-sen Moderu Niju Ichi” (Model 21), yes, they understand. Of course you can find “A6M2” written in all Japanese aviation books and magazines, but nobody is using this when they speak and it’s not the first that comes to their mind when you talk about the Zero.

Another difficulty I often had was when I used some terms very common outside Japan, but not in use among Japanese. The words “torpedo bomber” don’t exist in Japanese when you speak about aircraft of that era. “Kate” was a bomber that could also carry torpedoes. That’s all.

Compare how the English and the Japanese Wiki refer to “Tenzan” (Jill).

English Wiki: The Nakajima B6N Tenzan (天山, Heavenly Mountain) (Allied reporting name: "Jill") was the Imperial Japanese Navy's standard carrier-borne torpedo bomber during the final years of World War II and the successor to the Nakajima B5N.

Japanese Wiki: The Tenzan was a carrier-based attack aircraft developed and deployed by the Imperial Japanese Navy as a successor to the Type 97 Carrier Attack Aircraft. 

“Dive bomber”? What’s that? 

Wiki explains:

The Imperial Japanese Navy classified and referred to aircraft capable of dive bombing as “bombers”, and aircraft capable of only level bombing and torpedo attacks as “attack aircraft”.

Of course there is a word for “dive bombing” (Kyukoka bakugeki) but not a word for “dive bomber”.

Another example is the word “interceptor”, also not in use in Japan. The word used in Japanese is “Kyokuchi Sentoki” (“local fighter”) which doesn’t mean much. It’s more like another type of fighter, not a specialized interceptor. I had great difficulty talking about the “Raiden” and its mission capabilities in comparison with the Zero with a group of Japanese aviation historians. 

And so, my solution to all the above is, when I’m about to meet Japanese aviation fans and such, to always carry with me Model Art #327 and we point to the aircraft we’re talking about. Army I can handle, give or take, but when they start talking about 97 Hikotei and 96 Rikko they lose me completely.

There is a US aviation historian who insists on using the Imperial Year system in his articles and books to be authentic and close to the Japanese terminology. This creates huge problems with non-Japanese readers who need a guide book by their side to understand what aircraft he’s talking about in every sentence. 

This is due to the fact that outside Japan, aviation enthusiasts are more familiar with referring to Japanese planes using terms and names such as Kawasaki Ki-61 “Hien”* (Tony). Is this what the Japanese typically used and continue to use? No, but are you prepared to change that now after 80 years since the end of WWII? Hmmm… 

I hope I answered your question, Alexander. I also hope you didn’t find this piece too long. I could have written a lot more but I tried to keep it as short as possible.

*NOT “HEIN” !!!

Nakajima "Kikka"

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.

The "Kikka" No. 2, which was transported to the United States after the war for investigation. Its engine was later removed, and today only the airframe is preserved and on display at the Paul E. Garber Facility of the National Air and Space Museum (NASM).

"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".

Kawasaki Ki-61 "Hien" (Tony) pt. 2 - video

Here's the second part of the video and for those interested, additional intriguing information about the "Hien" from the Japanese Wiki:

Nickname/Designation

The prototype designation, the Ki number, was Ki-61. The official designation, Type 3 Fighter, derives from its official adoption in the 2603rd year of the Imperial calendar (1943 (Showa 18)). According to Watanabe (2006, p. 153), the official adoption was in June 1943 (Showa 18), while according to Komine (2007, p. 143), it was October 9, 1943. Although mass production actually began in 1942, the "Type 2" designation was delayed until 1943 to avoid confusion, as there were already the "Type 2 Single-Seat Fighter" (Shoki) and the "Type 2 Twin-Seat Fighter" (Toryu).

Its nickname was "Hien" (Swallow), and unit names and abbreviations included Type 3 Fighter, Rokuichi, Ki no Rokuichi, and Rokuichi Fighter. Within Kawasaki, it was called "Rokuichi", but after the introduction of the Type 2, it came to be called "Ichigata" or "Nigata".

Some sources state that the nickname "Hien" was announced in the latter half of 1944, but it was actually announced in an article in the Asahi Shimbun dated January 16, 1945, reporting on the activities of the 244 Sentai, which was engaged in the air defense of mainland Japan. The article states that "its nimble agility resembled that of a swallow soaring through the blue sky, hence the name 'Hien' (Swallow)." Mitsui (1989, p. 20) explains that it derives from its distinctive style, characterized by its long, slender wings with a high aspect ratio. According to Ikari (2006, p. 127), the nickname appears in Kawasaki Aircraft's timeline as of January 1945. 

Kawasaki Ki-61 "Hien" (Tony) - video

The video features a Ki-61-I Hei that has just rolled out of Kawasaki Aircraft's Gifu factory. 

Before you start commenting "The Japanese copy of Bf109", as usual, here's what the Japanese Wikipedia has to say:

"Although it was sometimes referred to as the “Japanese Messerschmitt” due to its engine and airframe configuration, the aircraft was designed entirely in-house by the Kawasaki design team. Its design differed significantly from the Bf 109 in several key aspects, including the method of joining the left and right halves of the wing to the fuselage, the radiator layout, and the main landing gear structure. The only commonalities were the engine and the MG 151/20 cannon, which was later installed on some of these aircraft."

Nakajima G8N "Renzan" (Rita) - Extra info

Prototype Number 4 found at the Nakajima plant in Koizumi, Gunma prefecture. This was the one that was brought back to the USA for testing.

Extra info from the Japanese Wiki: 

Nakajima Aircraft proceeded with the design and development under Chief Engineer Matsumura Kenichi, and in October 1944, the first prototype was completed and successfully made its maiden flight on 23 October. However, due to a shortage of aluminum, the first prototype was unable to achieve the planned performance. Furthermore, while being moved to the hangar, a brake failure caused a collision, damaging the nose. As the turbosuperchargers were also incomplete, delivery to the Navy was delayed until January 1945. 

Prototypes 1 to 3 were primarily used to verify the condition of the airframe and its fittings; final performance tests using aircraft fully equipped with turbosuperchargers and armament were scheduled to begin with Prototype 4 onwards. Although high performance was anticipated, due to accidents and air raids, and the cancellation of production of the aircraft itself, sufficient test flights were not carried out, and its actual performance remains unclear. 

Although the "Renzan" Prototypes 1 and 2 were accepted by the Navy and began trials based at Oppama Airfield, Prototype 1 suffered an accident during a test flight landing in which the rear fuselage snapped. Following an investigation, it was found that the fuselage strength specifications in use at the time were inadequate for aircraft with a nose-wheel landing gear configuration; consequently, repairs were carried out alongside a redesign. 

As Oppama Airfield was cramped and unsuitable for testing heavy aircraft, and as US air raids on the Kanto region had intensified since February of that year, Prototypes 1 and 2 of the "Renzan" were airlifted to Misawa Naval Air Station in March to avoid these attacks. Flight tests aimed at overloading the aircraft were conducted there; however, due to the worsening war situation, the "Renzan" prototype program itself was canceled in June 1945. Tests using the turbosuperchargers were never carried out, and the aircraft were destroyed in an air raid at the same location in August. Nakajima Aircraft had halted work at the stage of manufacturing the fuselages for prototypes 5-8 at Koizumi Works, leaving a total of two aircraft-prototypes 3 and 4, which had been completed but not yet accepted-at the adjacent Koizumi Airfield. One of these was severely damaged by air raids, while the other remained in a partially damaged state. 

This damaged airframe (believed to be Prototype No. 4, though there are differing theories) was seized by the US military. After repairs were carried out using salvaged parts from Prototypes No. 1 and No. 2, which had been transported from Misawa, it was airlifted from Koizumi Airfield to Oppama in December 1945 under US military supervision. It was then loaded onto a ship at Yokosuka and transported to the United States. 

In June 1946, the transferred aircraft flew the 480-nautical-mile route from Newark Army Airfield to Patterson Airfield in Ohio at a speed of 110 miles per hour, covering the distance in 3 hours and 10 minutes against a headwind of 26 knots. Although one more test flight was conducted, subsequent flights were canceled due to the poor condition of the aircraft; for instance, even after refurbishment by the US military, only one of the four engines was capable of operating at full power. The aircraft was stored on the base as a candidate for display in the Air Force Museum, but was ultimately scrapped during the Korean War, and no examples survive today.

This photo and the next two, feature Prototype Number 2 found in Misawa base, Aomori Prefecture. It suffered serious damage on the fuselage, as can be seen in the photos, when it was strafed during an air raid.

I’d like to conclude these posts on the "Renzan" by sharing my thoughts on the aircraft.

The "Renzan" was supposed to be the replacement Navy bomber of the Mitsubishi G4M "Betty". If everything had gone well with the engines, it would be faster than the "Betty"; "Rita" max speed 320kt, "Betty" 254kt. 

"Rita" would also have significantly increased range; "Rita" 2130 naut miles, max 4030, "Betty" 3270 or 2340.

"Rita" would also have drastically improved defensive armament with the rotating dorsal and ventral turrets and the twin 20mm cannons on the nose and tail.

Other than that...nothing else. In my eyes Nakajima, again, strived to improve the Mitsubishi design by trying to correct some of its weaknesses but did nothing to improve the payload.

I'll keep it simple to be easily understood.

If an ordnance of 100 tonnes is necessary to damage an enemy airfield significantly enough so that it remains out of comission for a meaningful amount of time (one week), then 20 bombers carrying a payload of 5 tonnes (ex. Consolidated B-24 Liberator) would need to fly 3-4 missions. 

Now consider how many missions or how many aircraft would be needed if you have bombers that can only carry a one-ton payload. In fact, Japanese bomber crews frequently expressed frustration that any damage they caused to the enemy airfield during night missions was gone by the following morning. Certainly, credit goes to the Seabees, but this also clearly illustrates the critical shortcomings of the Japanese bombers.

Therefore, if the "Renzan" was not intended for strategic bombing missions but rather to function more as an attack bomber, akin to the "Betty," then Mitsubishi had already completed and started production of one the finest attack bombers: the Ki-67 "Hiryu" (Peggy).

All in all, I fail to see how the "Renzan" would be of any use to the Japanese Navy. A testbed for some improvements like the turrets and the turbosuperchargers, okay, but nothing more.

Nakajima G8N "Renzan" (Rita) Prototype - video

The video today features the acceptance and purification ceremony of the first Nakajima G8N "Renzan" (Rita) prototype, held on December 25, 1944, at the airfield adjacent to the Nakajima Aircraft Koizumi factory. The original 16mm film was shot by Kaneko Michio, who was at the time head of the Photography Section in the Design Department at Koizumi.

At 0:36 we can see the second prototype of the Nakajima G5N "Shinzan" (Liz) with tail marking "コ-G5-2" (Ko-G5-2).

At 1:07, following the purification ritual performed by a Shinto priest, a "tamagushi" is offered at the altar in front of the aircraft.

Kyushu J7W "Shinden" pt. 3

After the war concluded, certain outer surfaces of the initial prototype were damaged and were later fixed for delivery to the US forces that occupied the area.

As per Japanese reports, the second prototype (of which no images have emerged, to my knowledge) was nearing completion when the war concluded.

The attached photos feature the first prototype following its repairs, prior to being painted, awaiting delivery to the US military.

Here's what the Japanese Wikipedia say about the Kyushu "Shinden-kai" J7W2 equipped with a jet engine:

There is a theory that there was a plan to eventually convert the Shinden into a jet aircraft, known as the "Shinden-kai" (designation J7W2). The basis for this theory regarding the Shinden's jet conversion plan is a contribution to an aviation magazine by Kiyohara Kunitake, former Deputy Chief of the First Design Section in the Kyushu Aircraft Design Department.

In his article, Kiyohara wrote: “On June 5, 1944, either during the ‘Study Group on the Prototype "Shinden" Project Requirements’ held at the Air Technical Arsenal or following subsequent instructions, a member of the Air Technical Arsenal’s Engine Division stated, ‘Proceed with the design with the use of a gas turbine in mind.’ The engine to be installed on the "Shinden" would have a static ground thrust of 900 kg, equivalent to roughly 3,000 HP, and would likely achieve a speed of about 420 kt (780 km/h). However, a takeoff booster rocket would be necessary, and the plan was to treat this as an overload. It appears this was the Ne-130 jet engine then under development at Ishikawajima-Shibaura Turbine. Given the engine layout of the "Shinden," converting it to jet engines did not seem particularly difficult. I remember feeling excited and hoping it would be realized as soon as possible. Ultimately, this did not come to fruition, but the prototype of the twin-engine jet attack aircraft "Kikka," designed by Nakajima Aircraft, was also built at Kyushu Aircraft, and the war ended just as the first prototype was nearly complete.” he testified. 

However, no other specific records have been found indicating that the "Shinden" was designed with jet conversion in mind. Furthermore, while Nishimura Mitsuo, who served as the chief engineer for the "Shinden’s" powerplant installation, acknowledges that there was talk of jet conversion, he also testified that “no concrete progress had been made” toward its realization. The development of the Ne-130 jet engine—which was under prototyping at the time and slated for installation—had only just reached the stage of full-power testing near the end of the war and was not yet in a condition suitable for actual operation.

The reason for this was that its predecessor, the Ne 20, suffered from various fatal defects. As a result of these defects, its endurance was extremely short, with a maximum operational life of only 15 hours during design-phase full-power operation. These defects were also exposed during test flights of the "Kikka," which was being developed in parallel with the "Shinden" at the time, and no progress was being made toward resolving them. These defects were present not only in the Ne-20 but also in the Ne-130, which was under development at the time, and naturally, the "Shinden" was not in a condition to be equipped with them.

Furthermore, by the end of the war, Japan had virtually exhausted its supply of rare metals (such as nickel and chromium) necessary for manufacturing the heat-resistant metals essential for jet engines; the development of high-heat-resistant alternative metals to address this resource shortage was a major obstacle even for the exhaust turbine, as is often noted. Consequently, it is believed that even if a prototype engine had been completed, mass production would have been virtually impossible.

Allow me to conclude this series of posts on the "Shinden" by sharing my thoughts on the aircraft. Although undoubtedly distinctive, highly intriguing, and in simple terms, truly impressive, I think the "Shinden" ought to be regarded not as a "miracle weapon" but rather in a more realistic and pragmatic light.

The aircraft was primarily designed as an interceptor for the B-29. U.S. bombers flying at very high altitudes would necessitate the development and installation of a pressurized cabin in the "Shinden," something I have not read anywhere that was taken into consideration. The IJAAF was experimenting with pressurized cabins (Kawasaki Ki-108), but the Navy?

Bombers flying at lower altitudes would afford the protection of escort fighters, and the "Shinden" was not intended to engage in aerial battles with them. Even if that became feasible, by the second half of 1945, the Japanese military did not have enough highly trained fighter pilots to stand a chance. Training new pilots to fly this new high-performance interceptor would require many months. Given that Japan had nearly depleted its supply of high-quality aviation fuel, it is very difficult to see how new pilots would have been trained to reach a level of proficiency sufficient to make a difference. 

Most Allied sources mention that by the summer of 1945, the bombing campaign against Japan was nearly complete and the B-29s were mostly out of targets. Furthermore, during the invasion of the Japanese mainland, medium and low-altitude bombers would be deployed to support the ground forces, so again, not many B-29s would be in the sky for the "Shinden" to intercept. All in all, I see the "Shinden" as a design that could have made some impact if it had been completed, produced, and delivered to combat units by the end of 1944, to be thrown into combat at the beginning of 1945, rather than as a 1946 design. I can imagine in 1945 the 302 Kokutai having a bunch of "Shindens" led by Akamatsu and perhaps a night fighter version, a J7W1-S with a couple of cannons right behind the pilot's seat but in 1946...unlikely.

But hey, it went against Godzilla, didn't it?

The 14 Sentai "Sally" that demands correction!

Four years ago ICM, with ARAWASI help, released the beautiful Mitsubishi Ki-21 "Sally" kit and everybody was thrilled and very happy. That is until...some modellers realized it was a Model 1 and that most of them were overall gray. Oh, the mysery! Little chance to show off and make squiggles with my expensive airbrush for camo!!!! Buhuhu... 

Rather than waiting for ICM to issue a Model 2 kit featuring numerous interesting camouflage and tail marking choices, there’s been a pursuit to discover "interesting" (i.e. highly camouflaged) Model 1 "Sallys" and push the matter, sometimes resulting in historical inaccuracies.

And so, the opportunity for this small piece came when I recently saw photos, splashed all over the net, of an absolutely beautiful model from a friend and a very respected Japanese modeller that is unfortunately historically inaccurate. I definitely wouldn't object to the occasional modeller who got the kit and had fun with it; I'm not out there looking to correct the work of modellers - I'd rather not be part of the "history police." However, when a well-regarded and fairly renowned modeller, recognized for creating highly precise models, produces an inaccurate one, I feel compelled to express my concerns before others begin to replicate his model.

Here goes...

There were two "Sally" Models. Model 1 had Nakajima Ha-5 engines, and Model 2 had bigger and more powerful Mitsubishi Ha-101 engines. In Model 1, the engines were fairly small, and half of the wheels were hanging from the nacelles. The Ha-101 engines were bigger and required equally larger nacelles, and the landing gear was enclosed with doors. Check the illustration below to see these differences in the engine, nacelle, and wheel areas.

Top, Mitsubishi Ki-21 Model 1 Otsu.

Bottom, Mitsubishi Ki-21 Model 2 Ko.

The illustrations are from Maru Mechanic #29 and although not bad at all, there are issues with the non-existent windows between the wing root and the fuselage door. But more importantly, note the differences between the two models in the engine, nacelle, wheel area.

As we described for the first time in our Eagle Eye #3 publication, according to the official unit history, the 14th Sentai relocated back to Japan in April 1942, where they exchanged their old Model 1 bombers for new Model 2s and trained for about a month. According to veteran recollections, the tail marking the unit became famous during the Papua/New Guinea campaign was adopted while in Japan, i.e. the unit used a different tail marking on their Model 1s. Then the unit moved to Kuala Ketil in central Malaya, where they spent the rainy season in Burma training with their new bombers, now having 27 (36) bombers in its strength. In other words, the unit DID NOT operate any Model 1s after April 1942. There are no photos or records indicating it had any. Yet, illustrations have appeared that show 14th Sentai Model 1s in the P/NG theater.

This photo detail taken from a US bomber during a November 2, 1943, raid against Rabaul, features a 14 Sentai 3rd Chutai "Sally" and a second one belonging to the 81 Sentai under a camouflage net. This has frequently been cited as evidence of a Model 1 14 Sentai "Sally."

Many who are not familiar with the differences between Model 1 and Model 2 "Sallys" overlook the wheel doors indicated by the red arrow. These doors confirm that this is a Model 2 "Sally"; definitely NOT a Model 1.

"Rising decals" has included decals of this particular "Sally" in its RD72105 set. As you can see it depicts a Model 1, which is inaccurate. Furthermore, the vast majority of 14 Sentai "Sallys" had the individual aircraft number painted at the bottom of the rudder.

Well-known, very highly regarded and respected (and a friend) aviation historian Michael Claringbould has included 14 Sentai "Sally" illustrations in one of his books. The books are top notch and VERY highly recommended but the artwork is occasionally not on par with the text. The attached illustration shows a misleading and incorrect combination of Model 1 fuselage with a Model 2 Otsu turret. I reached out to Michael and inquired about his source for Model 1 14 Sentai "Sallys," and he referred to the above photo in Rabaul.

This 14 Sentai "Sally" illustration far more accurately showcases the way the unit's aircraft looked when operated in the P/NG theater. There are some issues with the fuselage windows (the artist was probably inspired by the MM illustration) and again the aircraft misses the individual aircraft number at the bottom of the rudder. 

I really wish modellers could wait until ICM releases their Model 2 "Sally." And let's not forget there is a war going on there in Ukraine, and the ICM headquarters was bombed, not by innocuous requests but with actual bombs.

Kyushu J7W "Shinden" Test Flight pt. 2 - video

Today's video features the first Kyushu J7W "Shinden" prototype taking off for the very first time, on August 3, 1945, from Mushiroda Airfield in Fukuoka. In the cockpit is a Kyushu Aircraft test pilot (Blue FAOW says it's LCDR Tsuruno!), and as you can see the small tail wheels helped a lot to prevent another propeller accident.

Here's some interesting information about the aircraft from the Japanese Wiki:

From 1942 to around 1943, LCDR Tsuruno Masayoshi of the Aircraft Division at the Naval Air Technical Arsenal (Kugisho) conceived and researched a forward-swept-wing fighter, aiming to develop an innovative fighter that would significantly exceed the performance limits of conventional fighters. Additionally, in 1943, CDR Genda Minoru, who had been appointed as a staff officer at the Naval General Staff, believed that the Zero-sen had likely already been thoroughly studied by the enemy. Seeking a groundbreaking fighter distinct from the Zero, he explored the development of a high-speed fighter but lacked the technical knowledge to propose such a design. However, thanks to Tsuruno's presence, who shared this vision, the development of the "Shinden" began.

Even during the development of the "Shinden", some held the opinion that “a shape not found in nature must have some sort of flaw. Tsuruno simply hasn’t realized it yet.” However, the project gained widespread support on the premise that, as long as the design was fundamentally sound, it was worth pursuing.

The Navy, which had already anticipated an invasion of the mainland by high-altitude bombers, tentatively approved the development of a prototype in February 1945. Kyushu Aircraft was selected as the joint development partner to handle the detailed design and manufacturing, as the company had recently completed development of the land-based patrol aircraft "Tokai" and had more capacity available than other aircraft manufacturers. Tsuruno and others from the Naval Technical Arsenal were assigned to the company to provide technical guidance.

When determining the required performance specifications, there were calls from the operational side (led by staff member Kofukuda) to equip the aircraft with air combat flaps, but the design team argued, “The premise is that this aircraft will not engage in dogfights.” Team member Kitano also countered, “If the flaps are fully extended, drag increases; if they are only half-extended, they will be inferior to the Raiden’s air combat flaps”. The Aircraft Division and Science Division of the Aviation Technical Arsenal questioned their effectiveness and advocated avoiding close-range dogfights, instead adopting a hit-and-run tactic that leveraged high speed, similar to the U.S. Army Air Forces’ P-51 and P-38. Despite a directive from CDR Genda, a staff officer at the Naval General Staff, stating, “We are pursuing this because we want a high-speed fighter capable of over 400 knots; we must not impose too many additional requirements that would reduce its speed”, it is reported that they ultimately decided to proceed with the installation of automatic air combat flaps and continued their deliberations.

Prototype

In May 1944, the 18th Experimental Interceptor Fighter "Shinden" was officially ordered into production, with the primary objective of intercepting Allied heavy bombers. Initially, the Navy’s requirement was to begin drafting in April 1944 and complete the aircraft by the end of that year. To meet this, Kyushu Aircraft mobilized not only local residents but also many female students and conscripted laborers from places such as Amami Oshima, Tanegashima, and Kumamoto to establish the necessary production capacity. At its peak, the workforce exceeded 50,000 people, and it was estimated that once mass production began, the plant would be capable of producing 300 aircraft per month. Additionally, regarding materials, there was a requirement to consider using iron, which was expected to be relatively abundant in the future.

In November 1944, Kyushu Aircraft, having assembled its engineers, completed the drafting work—which normally takes a year and a half—in just six months, producing approximately 6,000 drawings. That same month, Franz Paul, a German engineer from Henschel [couldn't find anything about him. Leave a comment if you know more] , visited the facility. Under his guidance, the team began creating modified drawings designed with mass production in mind.

From December 1944 through April 1945, the Nagoya Plant of Mitsubishi Heavy Industries, which was developing the “Ha-43-42” engine scheduled to be installed in the "Shinden", suffered catastrophic, irreparable damage from air raids by the U.S. military. This led to significant delays in development.

In March 1945, following a B-29 air raid on Tachiarai Airfield, Kyushu Aircraft decided to evacuate its factory to Harada in present-day Chikushino City. Parts were transported by ox-drawn carts in the middle of the night [as usual].

As we saw in the previous post, the aircraft suffered a propeller mishap and small tail wheels from "Shiragiku" were installed. For mass-production models, the main landing gear was planned to be moved rearward, and no wheels were to be attached under the vertical stabilizer.

On August 3, 1945, the aircraft successfully completed its maiden flight during a test flight. Test flights were conducted on the 6th and 8th as well, but an engine malfunction occurred, and the war ended while the team was in the process of contacting Mitsubishi Heavy Industries to order replacement parts.

Kyushu J7W "Shinden" Test Flight pt.1 - video

The video today features the first prototype of one of the most unique Japanese aircraft ever produced, the Kyushu J7W "Shinden", during taxiing tests.

The original 8mm film was shot by Engineer Kiyohara Kunitake, an 8mm film enthusiast who, at the time, served as Deputy Chief of the First Design Section at Kyushu Aircraft and oversaw the aircraft’s equipment, piloting, functions, powerplant, and armament teams. It was developed after the war, the image quality is not very good and yet it is a most valuable record of this rare aircraft type.

The location is Mushiroda Airfield in Fukuoka. The airport was built in 1944 by the IJAAF and was named Mushiroda Airfield. After the war, the United States Air Force used the airfield as Itazuke Air Base from 1945 to 1972. Today it is called Fukuoka Airport, the principal airport on the island of Kyushu and the fourth busiest passenger airport in Japan.

The exact date is unknown but most sources mention that these taxiing tests were conducted in late July 1945.

After being transported to the runway and purified by a Shinto priest, the president of the Kyushu Hikoki, the Chief Designer LCDR Tsuruno Masayoshi performed a ritual offering of sacred branches. The engine was then started, and the taxiing test finally began. An Army Type 100 Reconnaissance Aircraft Model 3 can be seen in the rear left.

Below are some captions from the old blue FAOW explaining what we see in the clip.

Before the test run began, LCDR TSuruno, wearing a Navy cap, took the pilot’s seat himself to check the engine’s condition. This first prototype was finally completed shortly after June 10 and transported to Mushiroda Airfield on the 15th; however, modifications and maintenance to the radiator and hydraulic systems took a full month, and the final inspection was conducted in mid-July inside the tunnel hangar at Mushiroda.

A view from the front during the engine test run. The Mitsubishi Ha-43 Model 12 engine, with a takeoff power of 2,030 hp (2,900 rpm), rotates powerfully, emitting a distinctive, piercing roar. Because the cockpit is high off the ground, a long ladder was placed against the No. 1 prototype; a boarding mechanism allowing for quick entry was scheduled to be installed before mass production began.

The taxiing test is about to begin. LCDR Tsuruno, with a tense expression, is about to enter the cockpit. The antenna mast protruding from the right side of the nose is for the Type 3 Ku-1 radio telephone. There is another one below the front windshield of the cockpit. 

A view from the front-left just before the taxi test. With the engine at full throttle, the shadow of the 6-bladed propeller, 3.400 m in diameter, is clearly visible. The designers and prototype development staff watch over the scene.

The first prototype of the "Shinden", piloted by Major Tsuruno, took off in a cloud of dust, but just as it seemed the nose was lifting slightly near the north end of the runway, the aircraft spun halfway around and came to a stop. It is shown here taxiing back a short while later. 

Upon shutting down the engine and inspecting the aircraft, it was found that the tip of the propeller had bent about 50 cm. This was caused by the nose rising too high during the run, causing the propeller to strike the ground. Afterward, the tail wheels from Kyushu K11W "Shiragiku" were temporarily attached to the underside of the wing. 

The propeller was replaced with one intended for the second prototype, and the “first flight” took place on August 3 which we will see in the following post.