Kawanishi N1K-J "Shiden/Shiden-kai" (George), Yokosuka Kokutai, LTJG Muto Kaneyoshi

Biography of the Ace from the Japanese Wikipedia that approaches the subject in a completely different way than the English version:

Muto Kaneyoshi (August 18, 1916 – July 24, 1945) was a Japanese naval officer. He was a flying ace during the Second Sino-Japanese War and the Pacific War; he was posthumously promoted two ranks, ultimately attaining the rank of Navy Lieutenant (Junior Grade).

**Biography**

He was born on August 18, 1916, in Oharu Village (present-day Oharu Town), Ama District, Aichi Prefecture, as the third son in a family of seven siblings (sisters and brothers)...His father had served in the Russo-Japanese War and was awarded the Order of the Golden Kite. At Kaneyoshi's strong urging, his younger brother Mitsuharu took the entrance exam for the Imperial Japanese Navy Academy; he passed as a member of the 73rd class and also became a fighter pilot. Mitsuharu recalled, "While my older brother had a bold and spirited personality, I believe he was extremely affectionate toward his parents and siblings. He was particularly considerate of our parents and showed exceptional filial piety. He was especially fond of me among the siblings; I still vividly remember the joy I felt when, during his leave from the Navy, he bought me things like an air gun and a camera—items my father would never have bought for me."...

On June 1, 1935, he enlisted in the Kure Naval Barracks and was assigned to the destroyer "Uranami". On December 23, 1935, he was selected as a trainee in the 32nd class of the pilot training program. He graduated from the course in July 1936 and underwent advanced training at the Omura Kokutai.

The Second Sino-Japanese War

In October 1937, he was assigned to the 13th Kokutai. He deployed to Shanghai and participated in the "China Incident". On December 4, 1937, he shot down an I-16 fighter piloted by Yue Yiqin of the Republic of China Armed Forces over Nanjing; this marked Muto's first aerial victory. On December 12, he was transferred to the 12th Kokutai. He distinguished himself in attacks on Nanjing, Nanchang, and Hankou, ultimately shooting down a total of five Republic of China aircraft and becoming an ace pilot of the China Incident. He returned to Japan in October 1938 and served as an instructor at kokutai including Oita, Suzuka, and Genzan. During his time at the Oita Kokutai, he also served as an instructor to Nishizawa Hiroyoshi.

The Pacific War

In September 1941, he was assigned to the 3rd Kokutai. On December 8, at the outbreak of the Pacific War, he participated in the attack on Clark Field in the Philippines, flying as the wingman (number two) to Lieutenant Yokoyama Tamotsu.

In April 1942, he was assigned to the Genzan Kokutai (renamed the 252nd Kokutai in November of that year). According to Lieutenant Mimori Kazumasa, even when other wingmen drifted away, Muto would stay right by his side; Mimori recalled that Muto's mere presence was reassuring, as he would say, "Rest assured, I will not leave your side no matter what happens."

Miyazaki Isamu described Muto as a small-statured yet cheerful and lively man who was liked by everyone, recalling: "Muto-san often cracked jokes and made those around him laugh. The tougher things got for him personally, the more he strove to act cheerfully and boost everyone's morale. Because of this, everyone affectionately called him 'Kin-san' or 'Kin-chan'" [or "Kane-san, Kane-chan"]. He participated in operations such as the Solomon Islands air campaign. On October 21, 1943, he married his wife, Kiyoko; because Muto was so busy, their wedding photograph was created by splicing together two separate individual portraits. According to Kiyoko, he was overjoyed when their only daughter was born, feeling relieved that his lineage would continue.

In November 1944, he served as an instructor at the Yokosuka Kokutai. In June 1944, he joined the Yawata Air Raid Defense Unit as part of a detachment from the Yokosuka Kokutai and deployed to Iwo Jima. On June 24, he engaged in intercepting U.S. Navy Task Force 58 aircraft—including Grumman F6F fighters—and later that day provided escort for an attack squadron, flying as the wingman to Lieutenant Sadao Yamaguchi. He participated in intercepting U.S. carrier-based aircraft units on July 3 and 4. After losing their aircraft to air raid damage, the detachment returned to the Japanese mainland. On February 17, 1945, flying a single orange-painted "Shiden-kai" fighter, he challenged a formation of twelve Grumman aircraft that had appeared over Atsugi Air Base and reported shooting down two of them. His tactic of luring enemy planes away from the group one by one to shoot them down was reminiscent of the duel at Ichijoji-sagarimatsu fought by the legendary swordsman Musashi Miyamoto; from that time on, he became known within the Navy by the nickname "Musashi Miyamoto of the Skies". When his colleague Yamazaki Taku parachuted into the Sugita area of ​​Isogo Ward, Yokohama, and was killed by locals with bamboo spears after being mistaken for an American soldier, Muto was enraged and contemplated strafing the area in retaliation.

In June 1945, he was transferred to the Fighter Squadron 301 (nicknamed "Shinsengumi") of the 343rd Kokutai. Captain Genda Minoru, the group's commander, had specifically requested him, seeking someone capable of serving as a wingman to protect the squadron leader, Lieutenant Kanno Naoshi, following the death in action of CPO Sugita Shoichi on April 15. Negotiations regarding the transfer—originally proposed as an exchange involving ENS Saburo Sakai—faced difficulties but were ultimately finalized after consultation with personnel bureau officials. The Yokosuka Kokutai opposed the exchange, with Lieutenant Tsukamoto Yuzo voicing particularly strong objections. Consequently, the terms were adjusted so that the 343Ku would release two pilots—ENS Sakai Saburo and ENS Noguchi Kijiro—in the exchange. Upon assuming his post, Muto promised Commander Genda, "Now that I am here, I will not let the squadron leader die".

Death in Action

On July 24, 1945, Muto took off from Omura as part of a 21-plane formation to intercept carrier-based aircraft from a U.S. task force that outnumbered them more than tenfold. During the ensuing engagement over the Bungo Channel, Muto attacked enemy formations and engaged aircraft that were targeting Squadron Leader Kanno. Amidst the fierce combat, Muto honored his promise to Commander Genda, but he failed to return from the mission. While the specific details of his fate remained unknown, the 343Ku lost six pilots that day, including Muto and Squadron Leader Oshibuchi Takashi. The unit was subsequently commended and received a formal message of praise from the Emperor for their actions in this battle. He was posthumously promoted to the rank of Lieutenant (Junior Grade). His confirmed aerial victory count during the Pacific War was 30 aircraft.

Model Art #439 "HEROES OF THE IJNAF IN 1937-1945," written by Osuo Kazuhiko, featured artwork by Nohara Shigeru that attributed Kawanishi "Shiden" Model 21 with tail marking "ヨ-104" to LTJG Muto. It was not the first time. Earlier Japanese publications also did so. Unfortunately, I have not located any photos of "Shiden" "ヨ-104" or other evidence that supports this claim, so I suppose this was based on veterans' recollections.

Kawanishi N1K-J "Shiden/Shiden-kai" (George), Yokosuka Kokutai

A collection of photos and artwork of Kawanishi N1K-J "Shiden/Shiden-kai" (George) belonging to the Yokosuka Kokutai from various sources.

This one, a N1K1-Ja "Shiden" (George) Type 11 Ko suffered heavy damage during an emergency landing.

Hasegawa has released a kit in 1/48, Nr.09870, of the aircraft

Unfortunately the entire tail number cannot be seen, but note the small yellow star above the horizontal stripe on the tail, signifying a kill.

"ヨ-107" (YO-107) was a N1K1-Ja "Shiden" (George) found by US forces after the end of the war. There is an inscription on the fuselage. We could not read the first part but the second part says: "and do not use this aircraft for spares" (don't remove parts of this aircraft to be used on other aircraft).

Another photo of the "ヨ-107" (YO-107) N1K1-Ja "Shiden" (George) seen in the previous photo.

Kawanishi N1K-J "Shiden/Shiden-kai" (George), Yokosuka Kokutai, WO Ohara Ryoji

Photos and artwork featuring a Kawanishi N1K2-J "Shiden-kai" (George) belonging to the Yokosuka Kokutai with tail marking "ヨ-105" (YO-105).

There is a possibility that it belonged to Ace pilot WO Ohara Ryoji, seen in the photo below.

The pilot on the left is WO Ohara Ryoji; the other two are unfortunately unnamed. (Photo credit: Ohara Ryoji)

A set of photos and other material was recently on sale on Japanese eBay. I believe they belonged to Ohara. Among them, there was a photo, again of the Kawanishi N1K2-J "Shiden-kai" (George) with tail marking "ヨ-105" (YO-105). Unfortunately, the face of the pilot standing in front of it is not visible in the low-resolution image. It could be Ohara or a different pilot.

Here's the history of the pilot from the Japanese Wikipedia and extra information from Hata&Izawa:

Ryōji Ōhara (February 25, 1921 – November 2, 2018) was a military officer and fighter pilot in the Imperial Japanese Navy. He held the final rank of Flight Warrant Officer.

**Career**

He was born into a farming family in Miyagi Prefecture on February 25, 1921. In June 1940, he enlisted in the Yokosuka Naval Barracks as a general aviation rating. After serving at the barracks and the Chitose Kokutai, he became a trainee in the 4th Class C Flight Preparatory Course in May 1941 and joined the Tsuchiura Kokutai. He graduated from flight training in July 1942 and was assigned to the Oita Kokutai as a fighter pilot; there, he completed training on the Type 90 Two-Seat Trainer Fighter [Nakajima A2N] and the Type 95 Carrier-Based Fighter [Nakajima A4N]. In October of that year, he arrived at the Buin Airbase as a replacement pilot for the 6th Kokutai.

He experienced his first aerial combat on October 19, 1942, and on October 23, he engaged ten F4F Wildcats of VMF-121 over Guadalcanal, recording his first aerial victory. 

According to Hata&Izawa:

After achieving his first victory during the attack on Guadalcanal on 23 October [1942], ...Ohara participated in ferocious air battles in the Solomons, Rabaul, and New Guinea and managed to stay alive. In particular, on 13 May 1943 he sortied as number two (wingman) for LT Miyano during air combat over the Russell Islands and shot down one Corsair fighter. Immediately after, his own aircraft received thirty-eight hits and its horizontal stabilizer was damaged. He managed to extricate himself; on the way back, he valiantly counterattacked two Corsairs that were following him and shot down one of them. He then made an emergency landing on the island of Kolombangara. With respect to this particular air battle, Ohara was later given a good conduct commendation by the commander of Air Group 204.

Wiki continues:

Ōhara fought valiantly with the 204th Kokutai (renamed from the 6th Kokutai) until his assignment to the Yokosuka Kokutai in November 1943, at which point he returned to the Japanese mainland.

Subsequently, he engaged in the defense of the Japanese mainland. However, on April 9, 1945—while flying an interception mission against B-29s despite suffering from an unexplained high fever—his aircraft was hit by fire from a P-51 Mustang approaching from the rear. He managed to make a belly landing at the Army's Sagamihara Airfield; he was subsequently diagnosed with typhoid fever and required hospitalization for approximately 80 days. On August 17, 1945—after being discharged from the hospital—he flew a Zero fighter to intercept B-32s that had arrived to conduct reconnaissance over the Japanese mainland; this marked his final combat sortie of the war.

After the war, he joined the Maritime Safety Force (the predecessor to the Japan Maritime Self-Defense Force) in 1953 and retired in 1971 with the rank of Commander (equivalent to Lieutenant Commander in the US Navy). Subsequently, he engaged in training pilots for civil aviation.

He was incensed to find himself described as the "Killer of Rabaul" in a book on wartime history written by Henry Sakaida, which had been published without interviewing him; in later editions, the description was changed to "Ace of Rabaul."

He passed away on November 2, 2018, at the age of 97.

Artwork by Thierry Dekker

Hasegawa has released a kit with markings of the aircraft in 1/48, Nr. 09484

Nakajima B5N "Kate", Yokosuka Kokutai

Three photos of Nakajima B5N "Kate" Carrier Bomber photos belonging to the Yokosuka Kokutai.

Nakajima B5N1 "Kate" Carrier Bomber belonging to the Yokosuka Kokutai in standard pre-Pacific War IJNAF scheme; "silver," i.e., unpainted overall, red tail (vertical and horizontal surfaces), black anti-glare nose, hinomaru without white border.

Nakajima B5N2 "Kate" Carrier Bomber belonging to the Yokosuka Kokutai in early Pacific War scheme. Upper surfaces in green camouflage, lacking IFF stripes at this stage, meaning pre-October 1942, and fuselage hinomaru featuring a square border while wing hinomaru displays a round border. Note the white line on the cowling to help with formation during flight.

Nakajima B5N1 "Kate" Carrier Bomber belonging to the Yokosuka Kokutai found by U.S. forces after the end of the war. Overall green camouflage with heavily weathered surfaces around the cockpit but note that the fabric covered control surfaces and the cowling are completely unweathered. Hinomaru with round borders.

Kawanishi H8K "Emily" "Shikishima"

Somebody, somewhere posted this classic photo, taken in the summer of 1944, of the famous Kawanishi H8K "Emily" named "敷島" (Shikishima*), prompting me to collect details about the particular flying boat from different Japanese sources.

"Shikishima" was a transport aircraft for high-ranking officials. It was the third supplementary prototype of the H8K1 Experimental Type 13 Large-sized Flying Boat of which one prototype and four supplementary prototypes were built. The first prototype was powered by Mitsubishi Mk4A Kasei 11 engines while the supplementary prototypes were equipped with Mitsubishi MK4B Kasei 12 engines. These supplementary prototypes were redesignated Type 2 Flying Boat Model 11 on 5 February 1942. 

"Shikishima" belonged to the air unit attached to the Yokosuka Naval District, which operated out of the Yokohama Seaplane Base in Kanagawa Prefecture, as indicated by its tail marking (not visible in the photo) "横鎮74" (Yokochin74, without a hyphen). 

While its exterior was nearly identical to the standard model, the interior was modified to accommodate 27 passengers. In the passenger cabin on the second deck, there were wooden-framed single seats—nine on the right and eleven on the left—facing inward, while the second cabin featured inward-facing benches accommodating four people on the right and three on the left. The specifications for the "Shikishima" listed an empty weight of 16,084 kg and a fully equipped weight of 24,500 kg.

On the nose we can see the antennae of the Type 3 "Ku-6" Wireless Telegraph Set (三式空六号無線電信機) which was an aircraft-mounted radar system that the Imperial Japanese Navy put into use during World War II. The name "wireless telegraph set" was used to conceal its true nature. It is also known as the H-6 Radar or the Ku-6 Radar.

*"Shikishima" is another name for Japan, derived from the ancient site of Shiki, where the emperor's palace was located.

Nakajima Army Type Ko Model 4 Fighter / Nieuport-Delage NiD 29 - video

An extremely rare but short video today features Nakajima Army Type Ko Model 4 Fighters.

Here's what the English Wiki has to say about the type:

"The Japanese company Nakajima bought a pattern aircraft and built 608 for the Imperial Japanese Army as the Ko-4."

And here's what the Japanese Wiki has on the type:

In Japan, after importing 110 completed “NiD 29 C.1” aircraft, Nakajima Aircraft acquired the license to produce the aircraft. The first domestically produced aircraft made its maiden flight in December 1923, and 608 units were produced for the Imperial Japanese Army as the Type Ko Model 4 Fighter. In addition, the Army Artillery Arsenal produced 46 aircraft. Japan was the country that adopted the “NiD 29” (referred to in Japan at the time as the “Type ニ Model 29 Fighter”; “ニ” is the katakana initial of 「ニューポール」 (Nieuport)) in the greatest numbers worldwide.

The “Ko” type was manufactured by Nieuport, the “Otsu” type by Salmson, the “Hei” type by Spad, the “Tei” type by Farman, the “Bo” type by Cordonnier, and the “Ki” type by Henriot. The designation “Model 4” indicates that three other Nieuport models had already been adopted by the Imperial Japanese Army. "Model 3" was the Nieuport 24C.1 Trainer/Fighter, "Model 2" was the Nieuport 83 E.2 Trainer and, "Model 1" was the Nieuport 81 E.2 Trainer.

The engine installed in this aircraft was the “Mitsubishi Hispano-Suiza 300-horsepower engine,” a domestic version of the “Hispano-Suiza HS-8Fb water-cooled V-8 gasoline engine, 300 hp” produced at the “Mitsubishi Internal Combustion Engine Co., Ltd., Nagoya Works.” (The abbreviation for “Hispano-Suiza-type” was “I-type” in the Army and “Hi-type” in the Navy.) 

It employed a Lamblin radiator, which offered low air resistance, and was mounted at the base of the main landing gear.

This aircraft was the first fighter to be mass-produced by the Imperial Japanese Army. It was the first Imperial Japanese Army aircraft to be equipped with two 7.7 mm machine guns (the Imperial Japanese Navy’s Mitsubishi 1MF Fighter was the first to adopt them), which were mounted above the engine and in front of the pilot’s windscreen.

Although it served as the Imperial Japanese Army’s main fighter during the Manchurian Incident, it saw almost no actual combat and was later sold off to the civilian sector for use as training aircraft and other purposes. Its successor was the Type 91 Fighter.

Fiat BR.20 "Cicogna" in Japanese service

I was recently going through the Japanese propaganda videos dubed in Indonesian found in the Dutch archives. One video showcasing the "power of the Japanese Air Force" features a collection of short clips. Among them there is some really short footage of a Fiat BR.20 "Cicogna" operated by an IJAAF "jubakutai" (heavy bomber unit).

Although really very short, this is the only footage of a BR.20 in Japanese service I know of. Obviously the original would have included additional material, but regrettably, I believe it's unlikely it will ever surface.

According to the Japanese Wikipedia:

In 1938, 85 units of the late-model BR.20 were exported to the Imperial Japanese Army and deployed in the Second Sino-Japanese War under the designation "I-shiki" (Type I) Heavy Bomber. The aircraft served as an interim measure pending the introduction of the Type 97 Heavy Bomber [Mitsubishi Ki-21 "Sally"]; by the time the Type 97 was deployed to the front lines, stocks of Italian-standard bombs and spare parts had been exhausted, leading to the aircraft's withdrawal from frontline service. Nevertheless, the Breda-SAFAT 12.7mm machine guns with which the aircraft was equipped proved invaluable to the Army's development of its own aircraft machine gun, the Ho-103.

Type I Heavy Bomber (Fiat BR.20) flown by the 1st Chutai of the 98th Sentai.

Type I Heavy Bomber (Fiat BR.20) flown by the 1st Chutai of the 12th Sentai. 

(Photo Tanaka Shoichi via Jun Oizumi)

In case you didn't know, the best and immediately available (not ancient, out-of-print or inaccurate) reference for the "Sally" and the Fiat BR.20 in Japanese service, is the 3rd release in our Eagle Eye series.

Available from our online store: HERE

The Mindset Behind the Development Process of the Imperial Japanese Army Fighter Aircraft: Kawasaki Ki-60 & Ki-61 "Hien"

Let's begin with what Francillon has to say about the Kawasaki Ki-60 & the Ki-61 "Hien"

Ki-60:

"While negotiating with Daimler-Benz A.G. for the manufacturing rights for the German DB 601A inverted-vee liquid-cooled engine, Kawasaki were successful in impressing upon members of the Koku Hombu that most contemporary foreign high-performance fighters were powered by liquid-cooled engines. Consequently, in February 1940, Kawasaki were instructed to design around the German engine, or its Japanese version, two fighter aircraft: the Ki-60 heavy interceptor and the Ki-61, a lighter all-purpose fighter. "

Ki-61:

"While negotiating with Daimler-Benz, Kawasaki had approached the Army with initial design studies for various fighter aircraft making use of this engine. As reports from the air war in Europe were showing the apparent superiority of aircraft powered by liquid-cooled engines, the Koku Hombu instructed Kawasaki in February 1940 to proceed with two aircraft of this type: the Ki-60, a heavy interceptor, and the Ki-61, a lighter all-purpose fighter, priority being given to the heavier aircraft".

The Japanese Wikipedia and virtually all Japanese sources see things differently:

"In the summer of 1939, when the Nakajima Ki-43 "Hayabusa" [Oscar], was still undergoing evaluation, the Army began preparations for the development of a new fighter aircraft, exchanging opinions and conducting inspections with various companies. While air-cooled radial engines manufactured by Nakajima and Mitsubishi dominated the Japanese aviation engine landscape, Kawasaki had—since acquiring the manufacturing rights for the German BMW liquid-cooled V-type engine in 1924—developed, produced, and installed that engine (and its improved variants) in its own aircraft. However, the engine series culminating in the Ha-9 model had reached its performance limits, necessitating a shift to a new type. Meanwhile, liquid-cooled engines remained highly valued overseas for high-speed military aircraft; unable to abandon this technology, the Japanese military decided to domesticate the German Daimler-Benz DB601 engine. In 1937, the Navy assigned the acquisition of manufacturing rights to Aichi, while the Army assigned them to Kawasaki—both companies having prior experience in liquid-cooled engine production. Kawasaki, slightly lagging behind Aichi, dispatched a team of engineers to Germany in 1939 and invited technicians from Daimler to assist, ultimately completing the first domestically produced DB601A in December 1940. After further research, Kawasaki submitted plans for the light fighter KDA-21 and the heavy fighter KDA-22 in January 1940. 

Under the Japanese Army's "Research Policy" and "Research Schedule for Next-Generation Aircraft" dated 1940, the goal was to  first complete a "Type 1" interim model—equipped with two 20mm cannons and capable of a top speed in the 550 km/h range—by December 1940, followed by the completion of evaluations for this interim model by September 1941, with the development of the final operational version to proceed based on those results.

As this was essentially Japan's first attempt at a dedicated heavy fighter, the research schedule for future aircraft outlined a phased approach: first, an interim model armed with two 20mm cannons would be completed by December 1940 and undergo evaluation by September 1941; subsequently, a production-ready model would be developed based on those results. The target maximum speed for the final operational version was envisioned to be in the 640 km/h range.

In February 1940, acting on this policy, directives were issued for the development of the Ki-60 heavy single-seat fighter powered by the DB601A and the Ki-61 light single-seat fighter powered by the Ha-40 (the domestic version of the DB601A) as the next generation of fighters. The chief engineer for both was engineer Takeo Doi.

The first Kawasaki Ki-60 prototype.

The type incorporated various new technologies, such as a sliding canopy designed for improved rearward visibility, a retractable tailwheel, and—for the first time in Japan—retractable main landing gear that shortened in length during the retraction process. This shortening-retraction mechanism was adopted despite the resulting mechanical complexity and increased weight in order to narrow the spacing between the wing-mounted cannons.

The English Wikipedia has this about the Ki-60:

"From the start of flight testing, it became apparent that the design was seriously flawed in several key areas. The take-off run was unacceptably long, while, in flight, the aircraft displayed some lateral instability, excessively heavy controls, and poor control response. The spinning characteristics were described as "dangerous", and the stalling speed was extremely high. Although a top speed of 600 kilometres per hour (370 mph) had been projected the Ki-60 was only able to achieve 548 kilometres per hour (341 mph)."

The source is mentioned as "Green, William; Swanborough, Gordon (1976). JWW2 Aircraft Fact Files: Japanese Army Fighters, Part 1."

Curiously, absolutely no Japanese source mentions anything even remotely close to the above statements.

On the contrary, Japanese sources mention that:

"Test results confirmed that the aircraft achieved a maximum speed of 560 km/h at an altitude of 4500 m, a climb time of 6 minutes to 5000 m, and a service ceiling of 10000 m. This was about 15 km/h faster in maximum speed and 30 seconds faster in climb time compared to the Nakajima Ki-44 "Shoki", which had been completed and was undergoing testing earlier."

"In June 1941, during the height of the evaluation process, a comparative test was held in Kakamigahara between a Messerschmitt Bf 109E imported from Germany and Japanese fighter planes. The Ki-60 also participated in this test, and it was found that it could engage in aerial combat on equal or slightly superior terms with the Bf 109E.

Compared to its rival, the Nakajima Ki-44 "Shoki", the Ki-60 had superior turning performance as long as the Ki-44 didn't use its combat flaps, making it easier to pilot and take off/land than the Ki-44. The pilot of the Ki-60 at that time was Captain Kuroe Yasuhiko, who became captivated by the Ki-60's charm and a fan of it ever since."

Other Ki-60 details missing from all non-Japanese sources:

a. "the Ki-60 was armed with 20mm cannons and designed strictly for "hit-and-run" tactics."

b. "The engines installed in the Ki-60 were units imported from Germany to serve as samples for domestic production."

dc. "A total of three prototype aircraft were produced. Two of these were deployed to the 47th Independent Air Squadron alongside pre-production models of the Ki-44, but both were lost in accidents before they could see combat. The remaining aircraft survived until the end of the war."

Finally, completely contrary to what all non-Japanese sources say about the type, all Japanese sources agree that: 

"Although the aircraft was ultimately not adopted for service, flight test results indicated it was an excellent machine that fully met its design objectives."

The main reason for the Army rejecting the Ki-60 is that the Ki-61 "Hien", demonstrated unexpectedly outstanding performance. 

The second Kawasaki Ki-61 "Hien" (Tony) prototype (c/n 6102). The vision panels forward of the windscreen have been increased to two. Aiming for aerodynamic cleanliness and light weight, the Ki-61 achieved performance levels far exceeding those anticipated. In comparative trials against the Bf 109E, the Ki-61 was found to be superior in speed, climb rate, endurance and handling qualities.

As for the "Hien", here's a piece from the Japanese Wikipedia, that includes details largely absent from non-Japanese references:

"The design concept for the Ki-61 was that of a versatile fighter—sometimes referred to as a "medium fighter"—that did not strictly adhere to the "heavy fighter" or "light fighter" categories defined in the "Aviation Weaponry Research Policy." It is said that internal Army debate inevitably arose because the requirements for light single-seat fighters demanded not only maneuverability and climbing ability but also the installation of 12.7 mm cannons. Deputy Chief Engineer Owada stated that "a fighter aircraft must surpass the enemy in overall performance; categorizing them into 'light' and 'heavy' fighters is irrational", a view that was shared by the entire Kawasaki development team. Some sources even indicate that the development team referred to the concept as a "medium fighter", suggesting the idea originated with Kawasaki.

Doi himself stated that he sought to craft the Ki-61 into an ideal fighter, without being bound by the Army's "light fighter" doctrine. Detailed design work began around September 1940. 

Additionally, Watanabe Yoji in his "The Liquid-Cooled Fighter “Hien”: The Silver Wings of a Japanese-German Collaboration" notes that as early as May 1940—during the initial development phase—Doi had already discussed the possibility of equipping the Ki-61 with an air-cooled engine.

The wooden mockup review took place in June 1941 [23], and the prototype was completed and made its maiden flight in December 1941. Although some sources suggest that the Army had low expectations for the Ki-61—given that it utilized an engine of the same family as the Ki-60—it achieved a top speed of 590 km/h during testing, surpassing both the Ki-60 and the Bf 109E by 30 km/h. This level of performance was entirely unexpected, even by its designer, Doi. For context, other Army fighters of the era had lower top speeds: the "Hayabusa" (a "light fighter") ranged from 495 km/h to 515 km/h, while the "Shoki" (a "heavy fighter", prior to official adoption) topped out at 580 km/h. Consequently, Doi and Owada were awarded the Mainichi Aviation Prize in October 1942 and the Army Technical Merit Award in December 1943.

The Mindset Behind the Development Process of the Imperial Japanese Army Fighter Aircraft: Part #1 "Hayabusa" & "Shoki"

Let's begin with what Francillon has to say about the "Hayabusa":

"Design work on the Hayabusa began in December 1937 when the Army, giving up their long-standing policy of awarding competitive contracts to Japanese manufacturers, instructed Nakajima Hikoki K.K. to design a single-seat fighter to supersede the Army Type 97 Fighter (Nakajima Ki-27)."

And about the "Shoki":

"Shortly after instructing Nakajima to proceed with the design of the Ki-43, the Koku Hombu gave them their specification for an interceptor fighter. In a pronounced departure from previous Japanese standards, speed and climb rate were emphasized at the expense of manoeuvrability. The Ki-44, as the project became known,..."

The English Wikipedia entries heavily rely on Francillon and basically repeat the above.

But let's see what the Japanese Wikipedia has to say about the mindset behind the development of these two fighters and the "Army Aviation Weapons Research Policies":

The Nakajima-built Type 97 Fighter (Ki-27 "Nate"), officially adopted in December 1937, featured an ambitious design—the Army's first all-metal, low-wing monoplane—despite its conservative fixed landing gear. It was an excellent dogfighter with superior climb rates and maneuverability. However, by the time the Type 97 appeared, the Bf 109 (Germany) and Spitfire (UK)—both featuring retractable landing gear—had already emerged in Europe, prompting the Army to explore the development of new fighters.

In the "Army Aviation Weapons Research Policy" for the 1937 fiscal year—formulated by the Army Aviation Headquarters while the Ki-27 was under development—single-seat fighters were defined in two categories: "machine-gun equipped" and "autocannon equipped." The aircraft developed in accordance with these specifications were the Ki-43 (for the former category) and the Ki-44 (for the latter). 

The "Army Aviation Weapons Research Policy" for the 1938 fiscal year further refined these categories into "Light Single-Seat Fighter" and "Heavy Single-Seat Fighter" and added a third: the long-range two-seat fighter based on the concept of a twin-engine multi-role fighter. 

Based on this, instructions for the research and development of both "light" and "heavy" fighters were issued to Nakajima, Kawasaki, and Mitsubishi; Nakajima’s responses were the Ki-43 (Type 1 Fighter "Hayabusa") for the light fighter category and the Ki-44 (Type 2 Fighter "Shoki") for the heavy fighter category (Chief Engineer Koyama Yasushi led the design teams for both). Aoki Kunio, an engineer on the Ki-43 design team, stated that while the "Hayabusa" was also intended to be a heavy fighter (modeled after the Bf 109), the team's lack of experience in heavy fighter development resulted in it becoming a light fighter instead. 

Although proponents of light fighters argued that the Ki-44 was unnecessary, the development process—which had previously stalled—was revitalized following lessons learned during the Nomonhan Incident in 1939. Combat experience showed that Soviet Red Air Force fighters were effectively employing "hit-and-run" tactics, creating a recognized need for a cutting-edge fighter capable of executing such attacks and pursuing high-speed aircraft like the I-16.

According to FAOW #65 the attached photo features:

"the third (aircraft number 4303) of the three Nakajima Ki-43 "Hayabusa" (Oscar) prototypes built in 1939. Its shape differs considerably from that seen in full-scale models and drawings due to modifications and upgrades made to the prototype aircraft from late autumn of 1940 to early 1941. The rear fuselage, canopy, and the position of the slightly longer antenna mast, among other things, became almost identical to the production model. However, the flaps were still of the split type, and the armament covers and muzzles remained for 7.7mm guns. The reason why only two fuselage stripes were painted on the third prototype is unknown."

But note the very unusual yellow (?) band starting from the canopy side and continuing on the wing.

Unlike the Ki-43, the Ki-44 faced delays; the Army and the manufacturers lacked experience with heavy fighters, making it difficult even to finalize basic specifications, and consequently, its development schedule was prioritized below that of the Ki-43. Before the Army had even issued its formal performance requirements, Nakajima proceeded with development by setting the Bf 109 as a benchmark. According to Aoki, the "Shoki" was intended as an insurance measure in case the "Hayabusa" was not adopted, and it possessed strong characteristics of an experimental aircraft. This nature allowed Nakajima to incorporate new technologies and concepts into the "Shoki".

Drawing on lessons from the Nomonhan Incident and research into Western aircraft trends, the Army recognized the importance of protective measures. Consequently, the Ki-44 was equipped not only with fire-resistant fuel tanks (self-sealing tanks featuring a multi-layered rubber casing to prevent leakage and ignition upon impact—a feature the Army had previously ordered Nakajima to install starting with the Ki-43 prototype) but also, for the first time on a Japanese fighter, a 13 mm thick armor plate behind the pilot's seat for protection. This armor plating covered the headrest and backrest areas, with a total weight of 60 kg.

At the initial development stage, the armament requirements called for one fixed cannon and two fixed machine guns. The configuration consisted of two 12.7 mm cannons (Ho-103 Type 1 Fixed 12.7 mm Cannon)—utilizing newly developed high-explosive ammunition—mounted in the wings, and two conventional 7.7 mm machine guns (Type 89 Fixed Machine Gun) in the nose. It also featured a retractable tailwheel, a rarity among Army aircraft.

The prototype made its maiden flight on June 4, 1940. However, due to insufficient engine performance and numerous technical issues, various improvements were implemented. However, compared to conventional fighters, it was inferior in turning performance; the large-diameter engine resulted in poor forward visibility; and its high stall speed necessitated high-speed landings. On the other hand, it demonstrated excellent accuracy in firing tests, and in mock dogfights held in the summer of 1941 against a Bf 109 E-7 imported from Germany, the Ki-44's overall performance surpassed that of the Bf 109 E. Consequently, it was deemed a valuable asset capable of countering the latest Western fighters, though it remained unpopular among many veteran pilots who favored agile dogfighting capabilities.

According to FAOW #16 the attached photo features:

"the first prototype Nakajima Ki-44 "Shoki", serial number 4401, completed in August 1940. The photograph was taken in December of the same year at Tachikawa Airfield during operational testing, and the tail section of what appears to be the second prototype is visible on the far right of the frame. Due to the lack of a suitable high-powered engine, it was equipped with the Nakajima "Ha-41" (1,250 hp), a large-diameter bomber engine, resulting in an extremely wide nose. Only the first prototype differs from the second and subsequent prototypes in its cowling shape, cowl flaps, the air outlet immediately behind them, and exhaust pipes. The paint scheme is the Army's basic gray-green, and the stripe on the rear of the fuselage indicates that it is the first prototype."

In the "Army Aviation Weapons Research Policy" for the 1940 fiscal year, the "heavy" versus "light" fighter distinctions were explicitly codified. The "Heavy Fighter" evolved into the primary, all-purpose fighter—featuring high speed, heavy armament, superior range, and robust armor protection—capable of engaging both enemy fighters and bombers. Conversely, the "Light Fighter" was relegated to the role of an auxiliary fighter, prioritizing dogfighting but accepting compromises in performance and equipment to focus primarily on combat against other fighters. 

In December 1941, Nakajima received a preliminary directive for the Ki-84 as an advanced iteration of the "Heavy Fighter"; this aircraft was later officially adopted as the Type 4 Fighter "Hayate". This aircraft emerged as the definitive, all-purpose fighter, excelling in speed, armament, armor protection, range, maneuverability, handling, and ease of production. 

In the subsequent "Army Aviation Weapons Research Policy" for the 1943 fiscal year, the distinction between "light fighters" and "heavy fighters" was abolished; the "light fighter"—already an obsolete compromise—was absorbed into the "heavy fighter" category and redesignated as the "short-range fighter" (or "Kinsen"). That same policy introduced additional categories: "long-range fighter" ("Ensen"), "high-altitude fighter" ("Kohsen"), and "night fighter" ("Yasen").

P.S. This piece should teach a lesson to those who rely only on English sources, especially antiquated ones, and completely ignore the work of Japanese aviation historians!

Questions!

Wooden Propeller Blades

I had a question regarding the use of wooden propellers in the IJAAF/IJNAF.

The standard painting methods seem to not apply to them, yet at the same time, a consistent color is also not clear...

I have not seen one with any warning strips either.

The use of them in trainers is clear, but also on early seaplanes. They range from a dark color, possibly stained wood, or perhaps even painted in the brownish color late war metal propellers were... But then at the same time, lighter colors exist, such as the K5Y with a grey looking one! In all cases, the metal leading edge is still clear, either lighter, or darker, but always distinct from the propeller color.

If painted, what colors would they be? Were there any standards for wooden propellers, and was the leading edge made from metal, or brass, like earlier aircraft propellers?

It's an interesting thought that I've not seen brought up before... Most modellers simply paint them the "standard" look, but I have seen some in nice wood, to simply black overall.

Any insight on this would be great, thank you for your time! -NJ

Answer:

From the Taisho era through the early Showa era, Japanese wooden aircraft propellers were crafted by laminating and gluing high-quality lumber—such as mahogany, walnut, and cherry—and then shaping the resulting blocks using tools like hand planes. Prominent manufacturers included companies like Yamaha, known for musical instrument production, established on October 12, 1897 as Nippon Gakki Seizo Co., Ltd. In 1921, at the request of the Imperial Japanese Army, began manufacturing wooden propellers for military aircraft, and in 1931, began manufacturing metal propellers.

The wooden propellers were covered with "urushi"*, and had metal tipping to protect them from damage from rain, pebbles, and runway debris. 

The attached photograph shows the scene of propeller manufacturing at the factory of Nippon Gakki Seizo K.K. (now Yamaha Corporation) in Hamamatsu City, Shizuoka Prefecture, around 1921. On the left, workbenches are lined up, and one can see artisans carving propeller shapes out of stacked wooden boards. In the background on the right, men in business suits and Army personnel are observing the work.

Nippon Gakki began manufacturing propellers in March 1921. Why did a company that made musical instruments come to produce equipment for military aircraft? The answer lies in the propeller manufacturing methods of that era. Propellers at the time were made of wood; creating them required artisanal skill to glue together hard, difficult-to-work boards—stacked at an angle to match the propeller's shape and then carve them down using a hand plane. Consequently, Nippon Gakki, which possessed advanced woodworking expertise gained from manufacturing wooden organs and pianos, was ideally suited to produce aircraft propellers.

A propeller manufactured by "Nippon Gakki" from Yamaha's official site.

An inscription on the side reads: "Manufactured by Nippon Gakki Co., Ltd., November 1925." Serial No. 155; Material: Walnut.

The propeller of a Type 13 training seaplane or Yokosuka K1Y.

A propeller attached to an Army engine used for training purposes.

A wooden propeller for the Navy's Type 90 Crew Trainer or Mitsubishi K3M "Pine". It measures 2,750 mm in total length and weighing 17.04 kg.

IJNAF propellers and struts from the collection of Kojima-san.

The propellers of the trainers.

Initially the propellers of the Tachikawa Ki-9 "Spruce" and the Yokosuka/Kawanishi K5Y "Willow" were made from wood with metal tipping. Note the interesting and quite unusual propeller on this "Willow".

The propeller of this K5Y2 seaplane is closer to the standard dark brown seen in the previous photos.

The propeller and the skeleton remains of a K5Y at the "Tsukuba Kaigun Kokutai Kinenkan"

The propeller of the sole complete "Willow" survivor in Indonesia. I'm not sure if the propeller is original though.

Initially the propellers of the Tachikawa Ki-9 "Spruce" and the Tachikawa Ki-17 "Cedar" were made of wood with metal tipping similar to the propeller of the "Willow". But very soon they were treated to the "case hardening" or "encapsulated" method. This was devised by the German company Schwarz during the late Taisho and early Showa periods; to prevent damage from pebbles, ice, and the like, the propeller surface is encased in a celluloid coating reinforced with wire mesh. The wire mesh consists of 0.2mm-diameter brass wire, and the coating is a cellulose nitrate-based finish approximately 1mm thick. Additionally, a 0.5mm-thick brass strip—known as a "tipping"—is attached to the leading edge of the blade using wood screws or nails.

The propeller of this Ki-9 Koh in the attached photo could be an early wooden example without the "case hardening".

On the other hand, the propeller of this Tachikawa Ki-9 Otsu has been most probably "case hardened". Note the single white band on the edge of each tip.

Another "Spruce" propeller, this time with two white bands.

As can be seen in this "Spruce" photo, at some point, the metal tipping was discarded.

A photo of a Tachikawa Ki-17 "Cedar" with the propeller lacking tipping.

In this color (not colorized) photo of a "Spruce" that served with the Korean Air Force after the end of WWII, the propeller has most probably been repainted with the same paint used for the top surface camouflage. Note the lack of tipping.

A "Spruce" propeller still exists and is displayed in Japan, but some sources indicate it has been repainted, so the color seen in the photo is not the original one.

Some Japanese sources mention that the color of the "Spruce" propeller was either beige or light green depending on the celluloid coating.

HTH

*"Urushi" refers to the sap collected from the deciduous tall tree of the Anacardiaceae family, Toxicodendron vernicifluum (Urushi, scientific name: Toxicodendron vernicifluum), found in Japan, China, and the Korean Peninsula is a natural resin paint and adhesive primarily composed of urushiol. In addition, in Southeast Asia such as Vietnam, Myanmar, and Bhutan, there are natural resins commonly called lacquer, though their compositions and uses differ. Crafts made from lacquer are called lacquerware, and especially Japanese lacquerware, due to its high quality.

The traditional colors of lacquer as a paint are black and vermilion; black is used as pigments such as iron oxide powder and soot, while vermilion lacquer uses pigments such as bendo and cinnabar. It is also sometimes done using black and vermilion lacquer to distinguish the coat.

Nakajima J1N "Gekko" (Irving), 153 Kokutai

A set of photos feature Nakajima J1N "Gekko" (Irving) flown by the 153 Kokutai as indicated by the numbers "153-" and "53-" on the aircraft tails.

A late-model Nakajima J1N "Gekko" (Irving) Model 11 (J1N1-S) with the step on the dorsal fuselage removed. This particular aircraft has had its downward-facing guns removed.

The same Nakajima J1N "Gekko" (Irving) Model 11 (J1N1-S) seen in the previous photo. On January 5, 1945, this "Gekko" of the 153rd Kokutai, Sento 851 Hikotai, made an emergency landing at Taisho Army Airfield in Osaka due to engine trouble. The drop tanks under the wings were the same type as those used on the Zero fighter (300 liters capacity) and were painted light gray. The crew, consisting of Chief Petty Officer Takano and LTJG Hayashi, and others received eight aircraft, including this one, at Atsugi Air Base. Two of the aircraft, including Hayashi's, landed at Taisho on their way to Kanoya. They departed the following day, the 6th, and headed to Taiwan via Kanoya to rendezvous with the main force. Because all the aircraft stationed at Clark Air Base in the Philippines, where they were scheduled to deploy, had been withdrawn, the 851 remained in Taiwan.

A Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base. The inspection/maintenance hatch is open, and the hole through which the barrel of the Type 99 Model 2 cannon protrudes is clearly visible. The photograph was taken on February 12, 1945, one month after the defeat in the air battles over the Philippines. It is believed to be an aircraft of Sento 812 Hikotai, the last "Gekko" unit to advance under the command of the 153rd Kokutai.

The same Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base.

Sometimes the aircraft in this photo is identified in various sites and FB pages as a Kawasaki Ki-45 "Toryu" (Nick).  

One more photo of the same Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base. 

Artwork by Kuroki Hitomi, of the previously seen Nakajima J1N1-Sa "Gekko" (Irving) captured by US forces at Clark Air Base, featured in FAOW #57. 

Below is a set of photos featuring another 153 Kokutai "Gekko", tail code "153-71" captured by US forces at Clark Air Base. 

Note the "H-6" (officially the Type 3 Airborne Radio No. 6) radar antennae protruding from the fuselage sides. The H-6 was the most widely deployed radar for Japanese Navy aircraft, seeing extensive use in maritime search and patrol missions from 1944 onwards. It operated on a wavelength of 2 meters (150 MHz); specifications indicated a detection range of 95 km for large ships and 55 km for a single large aircraft.

Approximately 2,000 units of the H-6—which utilized a maximum-sensitivity detection method—were manufactured by Japan Radio Co. and Kawanishi.

Unit history from the Japanese Wikipedia:

As land battles in New Guinea intensified and a counteroffensive by the U.S. Army—which had been rebuilding its forces in Australia—loomed, there arose a need for long-range reconnaissance units operating on the front lines stretching from western New Guinea to eastern Dutch East Indies. The 753rd Kokutai, which had long been based at the Kendari airfield on Celebes Island and was responsible for bombing missions toward the strategic stronghold of Darwin, had also been performing long-range reconnaissance duties; however, it was being severely depleted without ever being able to return to the home islands. Consequently, the 153rd Kokutai was formed as a new unit dedicated exclusively to reconnaissance. However, initially, they were unable to procure reconnaissance aircraft. Consequently, even though they had a full complement of personnel, they could not conduct reconnaissance missions and could do little more than analyze and relay reconnaissance information obtained from Army air units. 

January 1, 1944: Established at Kendari Airfield with Hsinchu Airfield as its home base (authorized strength: 12 land-based reconnaissance aircraft; however, no aircraft were available initially).

Directly under the command of the Southwest Area Fleet and the 13th Air Fleet.

By March, reconnaissance operations began using Mitsubishi Ki-46 "Dinah" transferred from the Army. In early March, Yokosuka D4Y "Suisei" (Judy) arrived from the mainland.

March 5, 1944: Reconnaissance of southern New Guinea conducted with two "Suisei".

March 10, 1944: Reconnaissance of New Guinea commenced every 10 days using "Dinah".

March 30, 1944: Engaged in patrol and search operations over the waters north of New Guinea following the Palau Air Raid. Operations continued until the alert was lifted on April 8.

April 9, 1944: Ordered to advance into New Guinea; moved to Wakde Island Airfield off the coast of Biak Island. Began patrols on the 13th.

April 22, 1944: Ground operations began in Hollandia.

May 4, 1944: Reconnaissance of Hollandia after its fall; reported on the status of airfield repairs.　　　　　

Around this time, the Sento 311 Hikotai was incorporated, forming a mixed fighter-reconnaissance unit. 

Early May 1944: Withdrew to Sorong (Jefman) Airfield, the westernmost point of New Guinea. Avoided the ground battle on Wakde Island that began on the 18th.

May 25, 1944: Incorporated 12 aircraft from the 201st Kokutai, which was undergoing training in Davao.

May 27, 1944: The "First Operation Kon" was launched (Operation Kon was a three-stage Japanese military operation designed to support the Battle of Biak Island). Engaged in air patrol until the order to cease operations on June 3.

Dispatched two fighters from the main force to escort the 24th Sentai bombing enemy positions on Biak Island.

June 5, 1944: "Operation Kon II" launched. Resumed patrol duties along shipping lanes.

June 7, 1944: Ordered the entire unit to withdraw to Kendari. Abandoned equipment and withdrew from "Operation Kon".

Thereafter, engaged in reorganization efforts.

July 10, 1944: A major reorganization of the kokutai was carried out. Placed under the direct command of the First Air Fleet and withdrew to Davao.

Transferred the Sento 311 Hikotai to the 201st Kokutai and incorporated the disbanded 251st Kokutai as Sento 901 Hikotai.

July 25, 1944: As the first batch of procured aircraft, four "Suisei" and nine "Gekko" arrived in Manila.

Throughout August, patrol operations were impossible due to a shortage of aircraft, so the unit focused solely on analyzing intelligence from the Army’s 15th Sentai.

September 1, 1944: Air raids on Davao began.

September 2, 1944: Another air raid on Davao. Four "Gekko" engaged the enemy. Three "Suisei" began patrolling for enemy task forces.

September 9, 1944: During the air raid on Davao, the "Gekko" used Type 3 cluster bombs but failed to shoot down any enemy aircraft, resulting in the loss of all aircraft.

Mid-September 1944: Two "Suisei" and eight "Gekko" aircraft advanced to Nichols Airfield on Luzon Island.

Upon arrival, both the "Suisei" and six of the "Gekko" aircraft were unable to conduct patrols due to mechanical failures. Patrols were carried out with the remaining "Gekko".

September 21, 1944: During a pursuit following the air raid on Manila, the enemy fleet was discovered; one aircraft was lost.

September 22, 1944: The remaining one aircraft guided the Zero Fighter Squadron of the 201st Kokutai.

October 27, 1944: The Davao detachment began supporting "Operation Tago" (a joint operation by the Japanese Army and Navy to transport reinforcements to Leyte Island during the Battle of the Philippines).

Late November 1944: Ran out of aircraft.

January 9, 1945: The First Air Fleet was ordered to withdraw to Taiwan.

The vast majority of the 153rd Kokutai personnel were unable to evacuate to Taiwan during the rescue operations that continued until February 10th, and were left behind in the Philippines. The 15,000 aircrew members of all the air units that could not evacuate formed the "Clark Area Defense Unit" under the command of General Sugimoto Ushio, commander of the 26th Air Fleet, and were deployed to ground combat under the 2nd Tank Division of the Army. Commander Wada Tetsujiro, who was in command of the 153rd Kokutai personnel on the ground, died of illness on October 29th after the surrender and did not survive to return home.

The Experimental 9-Shi Medium Attack-Bomber (Ka-15)

There is a peculiar aircraft that makes its appearance in the video of the previous post. It has a bump on its nose.

This is an extremely rare footage of the very little known Experimental 9-Shi Medium Attack-Bomber (Ka-15), the intermediary type between the  8-Shi Special Reconnaissance Aircraft or Mitsubishi G1M and the Mitsubishi G3M "Nell".

Experimental 9-Shi Medium Land Attack Aircraft (Ka-15) with Kisarazu Kokutai crews just before takeoff heading for Omura. 

The commander of the Kisarazu Kokutai at that time was Captain Takenaka Ryuzo, seen here briefing the crews wearing a white Type 2 military uniform. We can see that the Experimental 9-Shi Medium Land Attack Aircraft (Ka-15) behind him has no tail markings. 

The aircraft was piloted by Flight Leader Lieutenant Commander Soga Yoshiharu (one rank higher when the video was shot), who led the attack force toward Omura; however, this aircraft did not actually participate in the transoceanic bombing mission. The Type 9 Medium Bomber was the aircraft on which Major Soga conducted tests; he was very fond of it and apparently flew it himself for a while, even using it for official flights. The figure in flight gear saluting in front of the Type 9 Medium Bomber is LCDR Soga. (Special thanks to Sato Nobuhiko for the aditional information)

One of the Hei Type Experimental 9-Shi Medium Land Attack Aircraft (Ka-15)

Encyclopedia has the following about the type:

In February 1934, the Navy instructed Mitsubishi to develop a prototype of the 9-Shi Medium Attack-Bomber to advance and put into practical use the previous 8-Shi Special Reconnaissance Aircraft. Mitsubishi assigned Engineer Honjo Kiro as the chief engineer, as with the 8-Shi Special Reconnaissance Aircraft, and the first prototype was completed in June 1935. The following month, flight tests were conducted at Kakamigahara by Pilot Kajima, yielding excellent results. Subsequently, Lieutenant Soga of the Navy took primary responsibility for flight testing. 

The main differences from the Type 8 Experimental Reconnaissance Aircraft were: (1) The engine was replaced with a Hiro Type 91 600 HP engine (2) The seat arrangement was changed to a side-by-side configuration for the pilot and co-pilot, with the commander’s seat and radio operator’s seat behind them, and a seat for the engineer and upper gunner between the front and rear spars. (3) Armament was reinforced, with 7.7mm machine guns mounted forward-upper, rear-upper, and rear-lower; the upper guns were fitted with retractable windshields, and the lower guns utilized a section of the fuselage underside that could be opened and closed. (4) A torpedo or bomb suspension device was placed on the underside of the fuselage, allowing for the carriage of one 800 kg torpedo or one 500 kg bomb, or two 250 kg bombs. (5) The main landing gear was changed to a single-leg configuration.

Aircraft Nos. 1, 2, 5, and 6 were equipped with two Type 91 water-cooled 600 HP engines, had wooden four-bladed propellers, and lacked flaps and a drop-down turret; the lower machine gun was designed to be fired from a prone position by opening a hatch. Aircraft No. 3 was equipped with two Type 2 Kinsei air-cooled 680 HP engines, had a wooden four-bladed propeller, and increased tail surface area.

Aircraft No. 4 was equipped with two Type 3 Kinsei air-cooled 790 HP engines, had a metal Hamilton Standard three-bladed variable-pitch propeller, and was fitted with cowl flaps. 

While the first six aircraft all featured the Type Ko seating configuration, aircraft Nos. 7–21 were of the Type Hei design, featuring an observation tower (leave a comment if you know a better word that can describe it) on the nose. They were equipped with two Kinsei Type 2 680-HP engines, had wooden four-bladed propellers, were fitted with flaps, and featured a retractable upper gun turret and a drop-down lower gun turret. Additionally, only No. 8 had its outer wing dihedral angle increased on a trial basis, and only No. 11 was equipped with two Kinsei Type 3 790 HP engines and Hamilton Standard metal three-bladed variable-pitch propellers. 

[Number of Aircraft Produced] From June 1935 onward

Type Ko (Type 91 600 HP x 2) 4 aircraft

Type Ko (2 x Kinsei Type 2 680 HP engines): 1 aircraft

Type Ko (2 x Kinsei Type 3 790 HP engines): 1 aircraft

Type Hei (2 x Kinsei Type 2 680 HP engines): 14 aircraft

Type Hei (2 x Kinsei Type 3 790 HP engines): 1 aircraft

Total: 21 aircraft

Developed from the 8th Experimental Special Reconnaissance Aircraft, which demonstrated excellent performance, this aircraft exhibited outstanding high performance as a twin-engine long-range aircraft, and the decision on the production model was urgently sought. There were two seating configurations: the Type Ko (Aircraft Nos. 1–6) and the Type Hei (Aircraft Nos. 7–21). A decision on which to adopt proved difficult to reach, and further delays were caused by engine and propeller testing, as well as other modifications. It was not until June 1911 that it was finally officially adopted as the Type 96 Land Attack Aircraft. In May 1936, Aircraft Nos. 2 and 5 were used to conduct a round-trip flight from Tateyama to Northern Manchuria. On the return leg, No. 2 encountered severe weather near Mingyuegou in Jilin Province, broke apart in mid-air, and crashed, resulting in the deaths of all five crew members. It was later determined that engine failure was the cause of the accident. Additionally, accidents sometimes occurred due to a drop in fuel pressure during takeoff and landing or when the engine was at low RPM, or due to landing gear malfunctions.