Mitsubishi Ki-46, part three

The Mitsubishi Ki-46 was introduced by the Imperial Japanese Army Air Force (IJAAF) in Manchukuo and China. A total of seven units were equipped with it. Sometimes, the Imperial Japanese Navy Air Service (IJNAS) also employed the type to perform certain reconnaissance missions over the Northern shores Australia and New Guinea.
The IJAAF used this aircraft in the reconnaissance role in unauthorised missions over British Malaysia during the months prior to the bombardment of Pearl Harbor. Later, during 1942 it was used for high-altitude reconnaissance missions over Burma, Indochina, Thailand and the Indian Ocean. The British Royal Air Force regarded the Ki-46 as an aircraft very difficult to counter, with very few successful interceptions. On 25th September 1944 Flying Officer Wittridge shot down a Ki-46 using a personally modified Supermarine Spitfire Mk.VIII. He had removed two machine guns and the seat armour and polished wing leading edges to gain extra speed. The American Top Ace of the World War II, Richard I Bong, flying a Lockheed P-38 Lightning shot down a Ki-46 over the coast of Papua New Guinea in late 1942.
During the latest stages of the war, in 1944-1945 the Ki-46 was modified as a high altitude interceptor with two 20mm cannons in the nose and one 37mm in an upwards-and-forwards position, copying Luftwaffe's Schräge Musik night fighter guns. These were used to shot down the Boeing B-29 Superfortress over the metropolitan Japanese islands. However, it lacked stability for sustained shooting of the 37mm cannon, had just a thin layer of armour plating, it had no self-sealing fuel tanks and was very slow to climb.
It was also assigned to whole 'Sentai' (Wings/Groups) and 'Chutaicho' (junior operational commands) in the IJAAF during the Pacific War.
Some of them were captured by the Allied, repaired and test flown. It seems that one of them was sent to the Soviet NII VVS (Aerotechnical Institute of the Soviet Air Force) for testing, making it the only Japanese aircraft to be sent to the VVS.

Sources:
1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-46
2. https://www.valka.cz/Micubisi-Ki-46-Sin-Sintei-Dinah-t28814 (translated when needed)
3. Bunrin Do - Famous Airplanes of the World 38 - Mitsubishi Ki-46 (translated)
3a: Translated captions can be found at: http://www.arawasi.jp/Dinahtrans.html

Mitsubishi Ki-46, part two

On 12th December 1937 the Imperial Japanese Army Air Force (IJAAF) issued a specification to Mitsubishi for a long-range strategic reconnaissance aircraft to replace the Mitsubishi Ki-15. The specification demanded an endurance of six hours and enough speed to avoid interception by any existing fighter at the time of development. Otherwise, it didn't constrain the design to a team led by Tomio Kubo, a graduate from the Aeronautical Section of the Faculty of Engineering at Tokyo Imperial University who got graduated in 1931 and whose aesthetics are deeply infused into the resulting design.
The design was a twin-engined, low-winged monoplane with a retractable underwing carriage. It had a small diameter oval-shaped fuselage with room for a crew of two with the pilot and the observer placed in individual cockpits separated by a large fuel tank. Extra fuel tanks were placed in the thin wings both inboard and outboard of the engines, giving a total fuel capacity of 1.490 L (328 Imperial Gallons). It was powered by two Mitsubishi Ha-26 radial engines which, in the first variant, they were rated at 863 hp each and were housed in close fitting cowlings developed by the Aeronautical Research Institute of the Imperial Tokyo University with the aim of reducing drag and improving pilot's field of view.
The first prototype flew in November 1939 from Mitsubishi's factory in Kakamigahara, Gifu, North of Nagoya. After being tested, it proved to be seriously underpowered and was slower than required by the specification as it only reached 540 km/h (336 mph) instead of the specified 600 km/h (373 mph). Regarding other aspects, testings were successful. Considering that the aircraft was still faster than the IJAAF's main fighter, the Nakajima Ki-43 and faster too than the Imperial Japanese Navy Air Service's (IJNAS) Mitsubishi A6M2 Zero (newly introduced into service back then) an order for an initial production was placed by the IJAAF as the Army Type 100 Command Reconnaissance Plane Model 1 (Ki-41-I).
In order to solve performance problems, Mitsubishi replaced the engines with Ha-102 radial ones which were able to yield up to 1.065 hp of power. These engines were basically Ha-26 fitted with two-speed supercharger. On this improved design, fuel capacity was also increased and empty weight was also reduced. It was in flying condition in March 1941 and was commonly known as Ki-46-II. This variant met the speed requirements of the original specification and was therefore ordered in a full-scale production with deliveries starting in July.
At first the Ki-46 was virtually inmune to any fighter interception, however it was soon realised by the IJAAF that improved Allied fighters such as the Supermarine Spitfire the Lockheed P-38 Lightning could contest this immunity, so in July 1942 they instructed Mitsubishi to produce a further improved version as the Ki-46-III. This variant was powered by two fuel-injected Ha-112 radial engines which were able of yielding 1.479 hp of power, it had a redesigned nose with a fuel tank ahead of the pilot and a new canopy, smoothly integrated into the extreme nose of the aircraft eliminating therefore the typical 'step' of the earlier versions. The single defensive machine gun present in earlier versions was also deleted. This new variant flew for the first time in December 1942 and showed significant higher speed 630 km/h (391 mph) at 6.000 m (19.700 ft) high. Thanks to its performance, it proved to be superior to designs made by other rival companies, such as the Tachikawa Ki-70 which didn't enter production.
Trying to achieve even more altitude performance, two prototypes were fitted with exhaust driven turbosupercharged Ha-112-II-Ru engines. These flew for the first time in February 1944.
During its production period ranging from 1941 to 1945, a total of 1.742 exemplars (other sources claim it was 1744) were manufactured. Thirty-four Ki-46-I, 1.093 K-46-II, 613 Ki-46-III and 4 Ki-46-IV all of them at Mitsubishi Heavy Industries, in Nagoya, Japan.

Sources:
1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-46
2. https://www.valka.cz/Micubisi-Ki-46-Sin-Sintei-Dinah-t28814 (translated when needed)
3. Bunrin Do - Famous Airplanes of the World 38 - Mitsubishi Ki-46 (translated)
3a: Translated captions can be found at: http://www.arawasi.jp/Dinahtrans.html

Mitsubishi Ki-46, part one, foreign users

The Mitsubishi Ki-46 was a twin-engine reconnaissance aircraft designed and manufactured in Japan. It was used by the Imperial Japanese Army Air Force during World War II, but it also saw action with other Air Forces during and after World War II:

• Communist China: The Red Army of China Air Force (The aerial brand of the Communist faction during the latest stages of the Chinese Civil War between 1945-1949) had two Ki-46 in strength captured probably in Manchuria after the capitulation of Japan. They served as ground-attack aircraft and trainer respectively and they served until the early 1950s after the People's Republic of China was proclamated.
• United Kingdom: In September 1945 a Japanese Ki-46-IIIa based at Kahan airfield, in the Malayan peninsula, was performing a reconnaissance mission when he received an order from the British to hand the two aircraft used by his unit to the Allied Technical Air Intelligence Unit, South East Asia (ATAIU SEA) due to the capitulation of Japan.
  The aircraft were delivered without propellers, though and, in October 1945 the orders were given to restore those two aircraft to an airworthy condition. It wasn't until January-February 1946 that one of those flew to Seletar airport, in Singapore to receive new British roundels. It was later shipped to the United Kingdom and nowadays it can be seen at the RAF's Museum. 
• France: After the War, France obtained two Ki-46-IIK with an extra seat, which was used as a trainer by the Japanese. They were assigned to the Escadrille de Liaisons 99 (Liaison Squadron 99) which was based at Tan Son Nhut Air Base, in Saigon and it wasn't until late 1945 that they were operational again.
  An additional Ki-46-II was obtained and restored, after great effort, in February 1946 only to be written off nine months later. It seems that there was also a Ki-46-III, which is not clear how it was painted so we decided to draw both possible colour configurations, and it crashed during takeoff on its first French flight attempt.
  The Ki-46 were never used in their original role by the French and they were used more as high-speed staff shuttles than reconnaissance aircraft. They withdrawn at the end of 1947.
• United States of America: One Ki-46-II which operated from Hollandia (nowadays Jayapura) was captured by US Army Troops when they liberated the Hollandia area on 23rd April 1944. During September 1944 that aircraft was repaired by ground crews of the 5th Air Force, 3rd Attack Group, 89th Attack Squadron to an airworthy status. It was repainted with USAAF markings and the emblem of the 3rd Attack Group was painted in the nose.
  In January 1945 it was shipped to mainland USA aboard USS Attu (CVE-102). It was test-flown at US Navy's Base in Patuxtent, NAS Anacostia and Eglin Air Force Base. It suffered a taxiing accident at Eglin airfield and was, most probably, scrapped.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-46

2. http://www.traditions-air.fr/index.htm (translated)

3. https://captured-wings.wikia.org/wiki/C/n_2846

4. https://wwiiafterwwii.wordpress.com/2015/08/30/wwii-japanese-aircraft-in-postwar-french-service/

5. https://www.rafmuseum.org.uk/documents/collections/1989-0307-AF-MITSUBISHI-DINAH.pdf

6. Bunrin Do - Famous Airplanes of the World 38 - Mitsubishi Ki-46 (translated as much as possible)