Yokosuka E14Y

 

During the 1930s the Imperial Japanese Navy (IJN) built a hangar-equipped-submarine fleet to perform reconnaissance duties with small recon aircraft. This was considered a tactical advantage as it allowed to carry out surveys without being detected.

For this task, some submarines were modified and the IJN issued a specification (named 12-shi) for a submarine-based airplane with reduced dimensions and detachable parts that could be assembled and disassembled in 10 minutes or less. For this project the Yokosuka Naval Air Technical Arsenal was contacted and tasked with the design of such aircraft. 

The E14Y 12-shi, designed by Mitsuo Yamada, and powered by a single Hitachi GK-2 Tempu 12 radial engine which yielded 335 hp of power, 296 hp at sea level, droving a two-bladed propeller, flew for the first time in September 1939 and was tested against the Watanabe E14W1, against the which, showed good performance with, however, some faults like stability problems and a lower range than expected. Those problems were solved in early 1940 by modifying the empennage and applying additional drift at the lower part of the fuselage. Once modified, it was tested again by the IJN showing satisfactory results and being accepted into production. 

Mass-production of the type was assigned to Watanabe which manufactured a total of 125 E14Y1 (the production variant of the type) between 1941 and 1943, when production of the type ceased. The E14Y1 (code-named 'Glen' by the Allied) was powered by a single Hitachi Tempu 12-cylinder radial engine rated at 340 hp for take-off and 300 hp at sea level. It was armed with one flexible rearward-firing 0.303 in machine gun placed at the observer's post and could carry up to 60 kg (132 lbs) of underwing bombs. The fuselage was made of steel tube structure covered with canvas, wooden panels and light alloy metals. It had a cockpit enclosed in a glazed long canopy which run up to the rear part of the fuselage. It had a crew of two, pilot and observer, sitting in a tandem configuration. The wings, of rectangular shape, were made out of wood with light alloy spars and covered in cloth. They were mounted low on the fuselage and had two pair of ailerons mounted outside of the wings trailing edge. Floats were metallic and were connected to the lower part of the fuselage by a removable tubular frame.

The E14Y1 was used extensively in the I-7, I-9 and I-15 submarine classes of the IJN. It was operationally used for the first time on 17th December 1941 to fly a recon mission over Pearl Harbor, launched from submarine I-7 to evaluate the damage inflicted on the US Navy ten days before. 
During the whole war it was used to perform recon flights over Allied territory. On 26th February 1942 the submarine I-25 emerged off the northern tip of King Island in Bass Strait, off the coast of Victoria, Australia and a E14Y was launched on a recon mission over the port of Melbourne. The flight took three hours over the course of which they successfully flew over Port Phillip Bay and observed the ships anchored off Melbourne before returning to I-25 and landing on its floats besides the submarine.
The E14Y1 was also the only Japanese aircraft to fly over New Zealand during World War 2, and second enemy aircraft to do so since the German Friedrichshafen FF.33 'Wölfchen' in World War 1. On 8th March 1942 Nobuo Fujita from I-25, photographed the Allied-build up at Wellington harbour. On 13th March he flew again over New Zealand, this time over Auckland, before the I-25 proceeded to Australia. A second flight over Auckland took place on the night of 24-25th May, this time by Warrant Officer Susumo Ito who flew its E14Y1 over the city, before returning to the I-21 submarine. Ten days later, on 1st June, Ito flew the reconnaissance flight which preceded the Japanese attack on Sydney harbour which sank the HMAS Kuttabul depot ship killing 21 seamen.
The submarine I-9 was also observed off the coast of New Zealand in early 1943, however, there are no records of any recon flight having been launched.
But its most famous flight was the incursion on mainland USA that took place on 9th September 1942, near Cape Blanco, Oregon.
On that day, submarine I-25 approached the western coast of the United States and, at the command of Nobuo Fujita and observer Shoji Okuda, the E14Y1 was equipped with four phosphorous incendiary bombs weighing 76 kg (168 lbs) each. They took off and flew 50 miles (81 km) inland, where the bombs were dropped, intended to cause forest fires, although the initial plan was to just drop propaganda leaflets in a nearby town. This first incursion was followed by a second one, which didn't cause any serious damage and was aimed to have an important psychological impact on the American population. 

Sources:

1st https://it.wikipedia.org/wiki/Yokosuka_E14Y (translated)

2nd https://en.wikipedia.org/wiki/Yokosuka_E14Y

3rd https://www.valka.cz/Jokosuka-E14Y1-Glen-t27318

4th https://www.valka.cz/Jokosuka-E14Y-12-Si-t45930

Lavochkin-Gorbunov-Gudkov LaGG-3, part one. Foreign users

 

The Lavochkin-Gorbunov-Gudkov LaGG-3 was a Soviet fighter aircraft of the World War 2 which was an improved version of the previous Lavochkin-Gorbunov-Gudkov LaGG-1. It was one of the most modern fighters available for the VVS (Soviet Air Force) at the time of Operation Barbarossa in June 1941, together with the Yakovlev Yak-1.

Some foreign countries got their hands at the LaGG-3:

• Finland: During Continuation War (1941-1944), the Finnish Air Force captured a single LaGG-3 of the first series which had to make a wheels-up forced landing on Finnish territory during early 1942. Coded as "Red 33", it was dismantled on 20th May and transported to a repair depot by truck.
  As the machine had sustained considerable damage during forced landing, reparations were not complete until 30th June 1944 as it had low priority. This machine received the registration of LG-2 and was assigned to Hävittäjälentolaivue 32, a fighter squadron equipped with the American-built Curtiss Hawk 75A. 
  On 19th July 1944 the LaGG-3 series 1 made another forced landing at Mensuvaara airfield due to an engine malfunction. It was repaired, but it was damaged again, beyond reparation on 30th August 1944 after the landing gear malfunctioned. 
  Another single LaGG-3 Series 4th was captured by the Finnish Air Force during Continuation War. It was coded as "Red 29" and made a forced wheels-up landing near Aunus, Karelia in early February 1942. It was later dismantled and sent to repair on 20th May. This machine was the first LaGG-3 to serve with the Finnish Air Force and was assigned to Lentolaivue 32 and, under the registration of LG-1, it was piloted by Warrant Officer V. Ikonen. 
  The LaGG-3 was intended to be used as an interceptor against the Petlyakov Pe-2 bomber. The first combat took place on 23rd March 1943 when a Pe-2 was chased, but was never caught. Despite many attempts during the Continuation War, the three Finnish LaGG-3 (another one was captured and received the code LG-3) never managed to shot down the Pe-2.
  Under normal circumstances only one LaGG was airworthy at a time, so they had to fly alone. The only patrol flight with more than one LaGG took place on 27th October 1943 and they got involved in a dogfight with a Pe-2 bomber and its escort of two MiG-3 fighters, but it ended up without losses for any side. 
  On 4th November LG-1 had a landing accident, where the pilot left uninjured, but LG-1 was sent for reparations. It was quickly repaired and reassigned to Lentolaivue 32 in early 1944. On 16th February it was involved in an aerial combat against a group of Pe-2 with an escort of two LaGG-3 with LG-1 shooting down one Soviet LaGG-3. After the end of Continuation War on 4th September 1944 an armistice was signed with the Soviet Union and the Finnish LaGG-3 were put in storage. On 1st April 1945 they received new markings, replacing the Finnish blue swastika with white/blue/white roundels. They were scrapped shortly after.
• Japan: In the spring of 1942 a Soviet pilot defected with his LaGG-3 Series 8th flying it to Manchukuo and making a wheels-up landing at a field near the town of Chiasmus. As the machine was in need of reparations, these were completed on 27th September and the machine undertook some evaluation flight supervised by Major Yamamoto from the Imperial Japanese Army Air Test Center. Those trials took place at Mutanchiang Air Base, in Manchukuo and the LaGG-3 lacked the lower wheels doors. The original pitot tube was replaced by a Japanese made one and the propeller remained in silver colours with red bands at the tips. The Soviet red stars were replaced by the Japanese Hinomaru. 
• Germany: After Operation Barbarossa, the Luftwaffe captured many LaGG-3. Some were used for evaluation and it is known that one appeared at a propaganda movie in 1943. As we couldn't find graphical evidence of this, the colours and registration displayed should be considered as speculative. 

Sources:

1. https://en.wikipedia.org/wiki/Lavochkin-Gorbunov-Gudkov_LaGG-3

2. Signal Squadron - Aircraft In action 163 - LaGG Fighters in Action

3. https://massimotessitori.altervista.org/sovietwarplanes/pages/lagg3/lagg3.html

Mitsubishi Ki-83

 

The Mitsubishi Ki-83 was a Japanese long range heavy fighter designed during the very late stages of World War 2, which never went beyond the prototype stage.

The Ki-83 was designed as a long range heavy fighter, designed by a team led by Tomio Kubo who also designed the Mitsubishi Ki-46. The Ki-83 was designed as an answer to a 1943 specification for a new heavy fighter with long range. 

The first prototype flew for the first time on 18th November 1944 and it was followed by three more prototypes. They showed great maneuverability for an airplane of that size. The prototypes were able of performing a 671 m (2.200 ft) diameter loop in 31 seconds at a speed of 644 km/h (400 mph). 

The Ki-83 was powered by two Mitsubishi Ha-43 Ru 18-cylinder air-cooled radial engines rated at 2.200 hp each and drove a four-bladed propeller. They were armed with two 30 mm Ho-155 cannons plus two more 20 mm Ho-5 cannons mounted in the nose. 

In spite of the American bombing campaign against Japan, the Ki-83 was set for mass production when Japan surrendered on 15th August 1945.

Both the existence and performance were kept secret during the war, even in Japan. In fact, it was completely unknown for the Allies, as demonstrated by the fact that it had not a reporting name. Most of the existing photographs of the type were taken during the post-war occupation of Japan, when the prototypes were seized by the United States Army Air Force (USAAF) and was repainted with American insignia. 

One prototype was tested by American aeronautical engineers and other experts and, when flying with high-octane fuel, it achieved a speed of 762 km/h (473 mph) at an altitude of 7.000 m (23.000 ft). 

There were also plans for a reconnaissance variant, named Ki-95 and for a further development, named Ki-103, but they didn't go beyond the drawing board.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-83

2. https://www.valka.cz/Micubisi-Ki-83-t1293

3. https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=1469

Mitsubishi Ki-67. Part two. Mitsubishi Ki-167 and Ki-109.

 

The Mitsubishi Ki-67's performance, when compared with other contemporaneous bombers, specially with the American ones, was remarkable. It had a level-flight top speed of 537 km/h (334 mph) making it faster than the B-25 Mitchell or the B-26 Marauder, but slightly slower than the A-20 Havoc. It had good maneuverability in high-speed dives, excellent sustainable rate of climb and outstanding agility with excellent turn rate, small turn radius and the ability to turn at low speeds. 

The Ki-67 was used in level bombing and torpedo bombing raids, as it could carry one torpedo attached under the fuselage. It was initially used in strikes against the US 3rd Fleet in Formosa and Ryukyu islands during 1944 and later, during the Battle of Okinawa, mainland China, French Indochina, Karafuto prefecture (AKA South Sakhalin - against the Soviets) and against B-29 air bases in both Saipan and Tinian. For these missions a special variant was used, equipped with three remote-controlled downwards-firing turrets.

There were also some kamikaze variants which saw action during the Okinawa campaign. One such variant was the Ki-67 "To-Go" which was an unarmed regular Ki-67 with two 800 kg (1.760 lb) bombs in bomb compartment. The Ki-167, nicknamed as "Sakura-dan" or "Sakura-bullet" was another kamikaze machine equipped with one shaped charge thermite bomb of 2.900 kg (6.400 lb) in the fuselage, just behind cockpit. The shape of the bomb projected the blast forward, projecting a jet which could reach nearly a mille with a blast radius of 300 m (980 ft). This variant was designed with the aim of destroying emplacements and tank concentrations in mind. Only 9 machines were produced.

The Mitsubishi Ki-109 was a twin-engined fighter variant which took advantage of the Ki-67's good maneuverability. It was foresaw as a night fighter first and day fighter later. 

The night-fighter variant, was just but a project, to work together with another Ki-109a, equipped with a radar/reflector (just like the Douglas Havoc II Turbinlite concept, but using invisible radio beams instead of a powerful searchlight) and the Ki-109b which was to be armed with a 37 mm Ho-203 cannon placed in an upward-firing configuration (similar to the German Schrage Musik, to destroy the target.

The day-fighter variant, of which two prototypes and 22 production machines were made, was armed with a 75 mm Type 88 Heavy cannon in the nose and one defensive 12,7 mm (0,5 in) Ho-103 Type 1 machine gun in the tail. It was powered by two Mitsubishi Ha-104 engines yielding 1.900 hp of power each. Some machines were powered with the supercharged version of the Ha-104 engine, the Ha-104 Ru.

There were many never-completed variants of the Ki-67, like the Ki-112, a bomber escort variant armed with eight 12,7 mm turrets and one 20 mm cannon, the Q2M1 Taiyo, a radar-equipped anti-submarine version of the Ki-67, intended for the Imperial Japanese Navy (IJN), the Ki-97, an intended transport conversion and the Ki-69 which was another escort fighter concept.

Sources:

1.  https://en.wikipedia.org/wiki/Mitsubishi_Ki-67

2. Bunrin Do - Famous Airplanes of the World 98 - Mitsubishi Army Type 4 Heavy Bomber (Ki-67) (Translated as best as we could)

Mitsubishi Ki-67, part one.

 

The Mitsubishi Ki-67 was a Japanese twin-engined bomber produced by Mitsubishi Heavy Industries and employed both by the Imperial Japanese Army Air Force (IJAAF) and the Imperial Japanese Navy Air Service (IJNAS) during World War 2. 

In 1941, the IJAAF issued an specification for a successor of the Nakajima Ki-49. This specification sought for a high-speed twin-engined heavy bomber which could be employed against the Soviets over the Manchurian-Siberian border. Unlike other Japanese bombers of the time, it was requested to have good defensive armament ,the ability to resist heavy battle damage and to be highly maneuverable to allow it carry out dive bombing attacks and low level escapes.

The Ki-67 was designed by a team led by Kyunojo Ozawa, chief engineer at Mitsubishi. It was an all-metal mid-winged monoplane with a retractable tailwheel undercarriage. It was also equipped with self-sealing fuel tanks and armour. Those features were common in American and British built aircraft but they were rare in the Japanese ones. It was powered by two 1.900 hp Mitsubishi Ha-104 radial engines and had a defensive armament of one 20 mm Ho-5 cannon placed in the dorsal turret plus five 12,7 mm Ho-103 machine guns, in nose, tail and each beam positions respectively.

It could carry a payload of 1.070 Kg (2.360 lb) in its internal bomb bay. This, made the Ki-67 a medium bomber, according to American and Western doctrines. In comparison, the North American B-25 Mitchell had a payload of 2.722 kg (6.000 lb), the Martin B-26 Marauder up to 1.814 kg (4.000 lb) and the Vickers Wellington up to 2.000 kg (4.500 lb). However, they rarely flew fully loaded as their range was reduced significantly. Japanese doctrine almost always bid for greater ranges with their maximum rated payload, giving this way, a strategical bombing capability, unlike their Allied counterparts, which were considered as tactical bombers.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-67

2. Bunrin Do - Famous Airplanes of the World 98 - Mitsubishi Army Type 4 Heavy Bomber (Ki-67) (Translated as best as we could)

Bristol Blenheim, foreign users, part one

 

The Bristol Blenheim was a British a British twin-engined light bomber designed and built by the Bristol Aeroplane Company (commonly known by 'Bristol'). The Blenheim was extensively used during the first half of World War 2, with some machines being used as trainers even until the end of the war. 

The main user was the British Royal Air Force (RAF), but the type saw also use under other users:

• Australia: The Royal Australian Air Force (RAAF) operated the Bristol Blenheim in two squadrons, Nos. 454 and 459. 
  No.454 was equipped with Blenheims in November 1942 when it was based in Iraq where they were used as trainers. They were in service until January 1943 when they were replaced by the Martin Baltimore.
  No.459, was formed in February 1942 with just six aircraft (two Lockheed Hudsons and four Blenheims Mk.IV). The Blenheims were kept until May when they were replaced by Hudsons.
• British Raj: The Royal Indian Air Force (RIAF) had some outdated Blenheim Mk.I bombers serving with the No.3 Coastal Flight based at RAF Dum Dum, close to the city of Calcutta in 1942. Due to blogger's tag limitation of 200 characters, this couldn't be included in the list and, also, the drawing should be considered as semi-speculative as we lack clarification about their operational service with the RIAF.
• Japan: It's known that at least one Blenheim Mk.I and one Blenheim Mk.IV were captured and employed by the Imperial Japanese Army Air Force (IJAAF), as some wrecks were found in Semarang, Java after the war, in August 1947. It's interesting to note that the hulk of the Blenheim Mk.IV discovered there, appears to be modified to serve as a transport with extra windows and, apparently, refitted with Nakajima Sakae engines. 
  As our drawings are based on old blurry photos, they should be taken as highly speculative on how they looked like when in Japanese service.
• Indonesia: In 1945 or 1946, Indonesian forces acquired a Bristol Mk.IV from unknown sources (some claims are made they were acquired from the Netherlands). The aircraft was re-engined with Nakajima Sakae engines, so it's possible it belonged to the Japanese and it was re-captured by the Indonesians when the Japanese left in 1945. 
  This machine had not only its engines replaced, but the frontal cockpit completely faired over too.
• New Zealand: No.489 Squadron of the Royal New Zealand Air Force (RNZAF) served under RAF's Coastal Command and it was equipped with the Blenheim from August 1941 until January 1942 when it was re-equipped with the Blenheim Mk.IVf, which were in service patrolling the North Sea until March when they were replaced by the Handley Page Hampden as the squadron was re-converted into an anti-submarine torpedo bomber unit.
• Turkey: Turkey ordered 12 Blenheim from the United Kingdom in April 1936, making the Anatolian country the second foreign user of the Blenheim (the first one was Finland). The first two machines were shipped by sea in October 1937 while the remaining 10 were ferried by air between March and June 1938. Additional eighteen machines were ordered and delivered between November 1938 and February 1939 with additional 10 Blenheim Mk.I being given to the Turkish Undersecretariat of Military Aviation (the forerunner of the modern Turkish Air Force) in 1940.
  Three additional Mk.IVs, plus 17 Mk.V were supplied in 1943. These more modern machines came from RAF Middle East stocks. They served with the Turkish 3rd Regiment of the 2nd Air Division, at Gaziemir Air Base, in Izmir.
• South Africa: The South African Air Force (SAAF) evaluated a single Blenheim Mk.I in 1938, but didn't order the type. This single Mk.I was assigned to No.31 Squadron, which served with the South African Coastal Command and was used in late 1939 in the search of the German Pocket Battleship Graf Spee. This aircraft also shadowed two Italian ships as they were heading to neutral Portuguese Mozambique in June 1940 when Italy entered the war. The Blenheim attacked one of the ships with guns and bombs and forced it to run aground. 
  In spite of this service, the type was judged unsuitable for the SAAF and was returned to the UK.
  In February 1942 the No.15 Squadron SAAF, replaced its Martin Marylands by Blenheim Mk.IVf when they were assigned to the No.201 Group RAF. Some of these machines were up-armed with an additional 20 mm cannon placed in the nose glazing. A detachment was assigned to Kufra Oasis in April 1942, to prevent its use by the Germans, but the three aircraft were lost in the desert. They were not discovered until 1959.
  Later, in July 1942 No.15 replaced the Mk.IV by Mk.Vs and they were rebased to Mariut, in Egypt, where they conducted anti-shipping operations and saw some distinctive action. The unit replaced its Blenheims by Douglas Bostons in July 1943.
  Two additional SAAF squadrons flew the Blenheim Mk.V, Nos.16 and 17 from November 1942 until June 1943 and January-May 1943 respectively. They operated over the Indian Ocean and they were replaced by the Bristol Beaufort and the Lockheed Hudson respectively.

Sources:

1. https://en.wikipedia.org/wiki/Bristol_Blenheim

2. https://en.wikipedia.org/wiki/List_of_Bristol_Blenheim_operators

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

4.Osprey Publishing - Combat Aircraft 5 - Blenheim Squadrons of World War 2

5. https://en.wikipedia.org/wiki/15_Squadron_SAAF

6. http://www.aviationofjapan.com/2016/06/japanese-blenheims-at-semarang-java.html

7. https://web.archive.org/web/20051214192414/http://nei.adf-serials.com/indonesian-aviation-1945-50.pdf

8. https://en.wikipedia.org/wiki/No._489_Squadron_RNZAF

9. https://en.wikipedia.org/wiki/No._454_Squadron_RAAF

10.https://en.wikipedia.org/wiki/No._459_Squadron_RAAF

11. https://www.iwm.org.uk/collections/item/object/205212382

12. http://www.adf-serials.com.au/2a8Blenheim.htm

Mitsubishi Ki-57, Japanese users

 

The Mitsubishi Ki-57 was a Japanese passenger and transport aircraft developed from the Ki-21 bomber.

Back in 1938 when the Ki-21 entered service with the Imperial Japanese Army Air Force (IJAAF) its capabilities attracted the attention of the Imperial Japanese Airways (often referred to with their Japanese acronym of DNKKK - Greater Japan Airways Co.). Therefore, a civilian version of the Ki-21 was developed. This had many aspects in common with its bomber counterpart, as it retained the Nakajima Ha-5 KAI radial engines rated at 950 hp each and some other details. It differed mainly in having the same wings moved down from a mid-wing to a low-wing configuration and the incorporation of a new fuselage which could accomodate up to 11 passengers. The civilian variant of this new version was called MC-20, while the military version was called Ki-57.

The first prototype of the Ki-57 flew for the first time in July 1940 and, in spite of a fatal crash suffered by the fourth prototype, it was ordered into production both for the IJAAF, the DNKKK and the Imperial Japanese Navy Air Force (IJNAF) which employed a small number of Ki-57-II, and was known as the L4M1. A total of 101 Ki-57 and MC-20s were manufactured between June 1940 and April 1942 at Mitsubishi's factory in Nagoya. 

The Ki-57-II was an improved variant powered by two Mitsubishi Ha-102 rated at 1.080 hp each, which also powered the Ki-21-II bomber. This variant also featured the revised engine nacelles that the bomber had. They were also 25 mph (40.23 km/h) faster than the Ki-21-I, had a higher service ceiling and could carry heavier loads. Production of the Ki-57-II began in May 1942 and it ran until January 1945 with a total of 306 machines completed (though, according to other sources, the total produced number was higher; 406).

The Ki-57 was, numerically speaking, the most important transport plane of the IJAAF, its main role the Ki-57 was employed in was communications and logistics, but it was also used in paratroop transport and saw service in every front where the Imperial Japanese Army was involved. Its biggest success came on 14th February 1942 when Ki-57s (together with same Kawasaki Ki-56s) of the 1st Raiding Air Regiment (Teisin Sentai) transported paratroopers to attack the oil refineries at Palembang, on Sumatra to prevent their destruction by the Allies before they fell into Japanese hands. 

As the war progressed, and the Allied increased their air superiority, the Ki-57 proved to be very vulnerable to enemy fighters. Dozens were lost when the Allies swept West, including many that encountered heavily armed American patrol bombers, which were not afraid to engage the defenseless transports. When the war ended, many surviving Ki-57s and L4M1s were repainted in white with green crosses painted over the Hinomaru (the Japanese roundel) and were used to ferry Japanese delegates to the surrender ceremonies. 

In 1942 every version of the Ki-57 received the Allied nickname of "Topsy".

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-57

2. http://www.historyofwar.org/articles/weapons_mitsubishi_ki-57.html

3. https://pacificeagles.net/mitsubishi-ki-57-type-100-topsy/

4. https://www.valka.cz/Micubisi-Ki-57-Topsy-t33121 (translated)

MItsubishi MC-21

 

The Mitsubishi MC-21 was a transport aircraft made by converting surplus Mitsubishi Ki-21-Ia (and later Ki-21-II) bombers that were withdrawn from frontline service due to their obsolescence. 

This machine was an interim design that pending the completion of the Mitsubishi Ki-57/MC-20, which was a purpose-built transport aircraft based on the design of the Ki-21 bomber. 

The exact number of converted machines remains unknown but some of them were converted from 1941 (though some sources state that, by 1940 some machines were already converted) onwards. According to our own research, there were already at least five MC-21-I registered in 1940, with the earliest machine registered in November 1939. A total of nine machines were ordered, but two of them were cancelled on February 1940 and August 1940, making a total of five MC-21-I. Regarding the MC-21-II (the transport conversion of the Ki-21-II bomber, powered by the more powerful Mitsubishi Ha-101 1.500 hp radial engine) there were approximately a total of 11 machines with the earliest examples being converted in July 1943. 

The MC-21 was produced by removing all military equipment and armament from the Ki-21. Some very initial version (posted here ) retained the glazed nose and dorsal greenhouse canopy of the bomber version, but both were later removed and the gaps faired over. With these changes, the MC-21 outperformed both the original Ki-21 and the Ki-57 purpose-built transport plane. 

Most of the MC-21s served with Dai Nippon Kokku Kabushiki Kaisha (DNKKK or Imperial Japanese Airways) as freighters, ferrying supplies between Japan, Korea and Manchuria. It was also possible to refit the interior of the aircraft to fit nine passengers. It's possible that an unknown number of Ki-21 bombers were also converted in the field, and served with the Imperial Japanese Army Air Force.

Sources:

1. http://www.historyofwar.org/articles/weapons_mitsubishi_MC-21.html 

2. https://en.wikipedia.org/wiki/Mitsubishi_Ki-21

3. https://www.valka.cz/Micubisi-MC-21-t41742

4. http://www.airhistory.org.uk/gy/reg_J-.html

Mitsubishi Ki-21, part three

 

To compensate for the heavy losses against both the Hawker Hurricane and the Curtiss P-40 which the Ki-21 had to fight after Pearl Harbor, the Imperial Japanese Army Air Force (IJAAF) introduced the Ki-21-IIb, which replaced the long greenhouse style dorsal canopy by a turret equipped with a single 12,7 mm (0,5 in) Type 1 machine gun. Cockpit canopies were redesigned as well and fuel capacity was also increased. Although the Ki-21 was used in every front of the Pacific War, it was obvious that by, as early as 1942, the design was starting to be obsolete and was increasingly being shifted away from front-line service. 

In spite of its obsolescence, it remained in service until the end of the war in various roles, like transport, bomber crew and paratroop trainer, liaison and communications, special commando and secret missions and kamikaze operations. 

Near the end of the war, during the Battle of Okinawa, the remaining Ki-21s were used by Giretsu Special Forces (Giretsu was an special forces unit comprised of paratroopers) were used in strikes in Okinawa and American targets on Ryukyu islands. One noted operation was an strike on the American-held Yontan and Kadena airfields on the night of 24th May 1945. Twelve modified Ki-21-IIb with their turrets removed, of the Daisan Dokuritsu Hokutai were sent to strike, each airplane loaded with 14 commandos. Five Ki-21s managed to crash land on Yontan, only one landed successfully. The remaining raiders, armed with sub-machine guns and explosives wrought havoc on the supplies and nearby aircraft, destroying 264.979 L (70.000 US Gal) of fuel and nine aircraft, and damaging 26 more on what was the last operational usage of this Japanese bomber.

The Allied codename for the type, initially was "Jane", but it was quickly changed to "Sally" as "Jane" was the name of Douglas McArthur's wife. When the Ki-21-IIb entered service, the absence of the long greenhouse canopy confused Allied observers, who thought it was a completely new type and named it "Gwen", however, it was quickly switched back to "Sally" when they realized their mistake. 

A total of 2.064 units of every variant were manufactured,  between March 1938 and 1944 when the last Ki-21-IIb was completed.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-21

2. https://www.valka.cz/Micubisi-Ki-21-Sally-t31499 (translated)

3. http://www.asisbiz.com/il2/Ki-21-Sally/Mitsubishi-Ki-21-Sally.html

Mitsubishi Ki-21, part two

 

Losses for the Ki-21 were high during early combat operations due to an insufficient defensive armament - the Ki-21-Ia was armed with three 7.7mm Type 89 machine guns in nose, ventral and dorsal positions - and self-sealing fuel tanks, with the aircraft's fuel system proving to be unreliable. To address those problems, the Ki-21-Ib was introduced. An additional defensive machine gun was introduced in the tail in an 'stinger' arrangement and was remotely controlled. Both horizontal tail surfaces and trailing edge flaps were improved and the bomb bay was enlarged. Fuel tanks were also partially protected with laminated rubber sheets. 

A third variant of the Ki-21-I was introduced in 1940. This variant had an additional 500 L (130 US Gal) auxiliary fuel tank, fitted in the rear weapons bay and two more machine gun placed in the beam position, making a total of six. Underwing hardpoints were also fitted to carry a total of four 50 Kg (110 lb) bombs externally and, in order to compensate for the increase in weight, the wheels were increased in size. 

By the time of the attack on Pearl Harbor and the start of the Pacific War, the Imperial Japanese Army Air Force's (IJAAF) main antagonist until then, the Republic of China Air Force (ROCAF) had been greatly improved to the point that the Ki-21-I's losses were mounting too high, so most Ki-21-Ia and some 21-Ib were relegated to second line and training duties. 

Front line units were equipped, from mid 1940 onwards with the Ki-21-IIa (Army Type 97 Heavy Bomber Model 2A). This variant was powered by the much powerful Mitsubishi Ha-101 radial engine which yielded up to 1.500 hp of power and was also equipped with larger horizontal tail surfaces. This variant was the standard for many IJAAF's heavy bomber squadrons at the beginning of the Pacific War and played a major role in the early campaigns of the War. For operations over the Philippines, IJAAF's 5th, 14th and 62nd Sentais (a Japanese unit equivalent to a Wing or Group), based in Formosa, attacked American targets at Aparri, Tuguegarao, Vigan and other targets in Luzon island on 8th December 1941. The 3rd, 12th, 60th and 98th Sentais, based in French Indochina bombed British and Australian positions in Thailand and Malaya attacking Alor Star, Sungai Petani and Butterworth (Penang) escorted by Nakajima Ki-27 and Ki-43 fighters. However, during those operations, the Ki-21 suffered heavy losses both from the Hawker Hurricane and the Curtiss P-40 Warhawk.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-21

2. https://www.valka.cz/Micubisi-Ki-21-Sally-t31499 (translated)

3. http://www.asisbiz.com/il2/Ki-21-Sally/Mitsubishi-Ki-21-Sally.html

MItsubishi Ki-21, part one

 

Back in 1936, the Imperial Japanese Army issued a requirement for a new heavy bomber to replace the Mitsubishi Ki-20 and the Mitsubishi Ki-1 bombers which were clearly outdated for the time. The requirement called for a crew of at least four men, a top speed of 400 km/h (250 mph) with an endurance of at least five hours and a bomb payload of 750 kg (1.650 lb). Those technical requirements were very ambitious for the time and very few twin-engine bombers could achieve such performance numbers.

Mitsubishi and Nakajima were asked to submit their proposals, with Kawasaki's one being rejected. Mitsubishi's design was an all-metal mid-wing cantilever monoplane with a retractable landing gear, ventral bomb bay and two Mitsubishi Ha-6 radial engines. 

The first prototype flew for the first time on 18th December 1936, with the second prototype, which differed from the first one in having a long greenhouse canopy instead of a ventral turret, flying in January 1937. In the ensuing competition against Nakajima Ki-19 (Nakajima's proposal), they found to be similar in performance numbers, being the Ki-21 better in speed and endurance and the Ki-19 being better as a bombing platform and its Nakajima Ha-5 engines being more reliable. In order to make a decision, two more prototypes were ordered from both Mitsubishi and Nakajima, with Mitsubishi ordered to switch its own 825 hp Ha-6 engines for the Ha-5 ones, used by Nakajima and vice versa. That third prototype of the Ki-21 featured a glazed nose similar to the Ki-19 and revised tail surfaces. Therefore, the Ki-21 proved to be superior and was ordered into production as the "Army Type 97 Heavy Bomber Model 1A" in November 1937.

Production aircraft began to enter service in August 1938, supplementing and replacing the Fiat Br.20 Italian bombers that had been purchased as an interim measure. 

The Ki-21-Ia was used in combat for the first time during the Second Sino-Japanese War by the 60th Sentai (an unit equivalent to an aviation Group or Wing in other air forces) from autumn 1938, performing long-range unescorted missions together with the Br.20 of the 12th and 98th Sentais. The Ki-21 proved to be more reliable, robust and better suited for the long Asian distances than the Br.20. Two additional Sentais, the 58th and the 61st were deployed to Manchuria in the summer of 1939 to operate against China, with aircraft of the 61st being heavily employed against Soviet and Mongolian forces during the Nomohan incident (AKA Battles of Khalkin Gol) in June-July 1939, when the Japanese forces launched their main attack.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-21

2. https://www.valka.cz/Micubisi-Ki-21-Sally-t31499 (translated)

Mitsubishi B5M

 

In summer 1935, the Imperial Japanese Navy Air Service (IJNAS) issued a specification, 10-shi, for a carrier-based strike-bomber with torpedo capabilities. The specification called for a maximum speed of 330 km/h (205 mph) , an endurance of up to 7 hours unloaded and 4 loaded with a single torpedo plus folding wings to facilitate its usage in a carrier. Those requirements exceeded by far the performance numbers of the winner of the previous specification, 9-shi,  the Yokosuka B4Y. Regarding armament, the 10-shi called for a total payload of up to 800 kg (1.764 pounds) plus a rear-defensive machine-gun. The resulting machine had to be powered by the Mitsubishi MK8 Kinsei radial engine. 

Two old rivals, Mitsubishi and Nakajima (which eventually won the contest with the famous Nakajima B5N), were called to participate in the contest, with Yokosuka not taking part although they won the previous contest.

Mitsubishi's project for the 10-shi, received the internal designation of Ki-16 and was designed by Jiro Horikoshi, designer of the successful A5M and the more successful A6M Zero. Inspired by the Northrop 5A (a prototype for the Northrop YA-13 which was sold to the IJNAS by the USA), Horikoshi decided to adopt a fixed landing gear, relying on the success of the A5M, covering wheels with a massive cowling. He also refused the mechanical wing-folding drive the 5A had in order to not overload the engine with additional tasks. 

The B5M prototype was completed in January 1937, almost at the same time the B5N's prototype was completed. Both bombers were tested and the B5M showed a slower speed than the B5N, 355 km/h (221 mph) versus 368 km/h (229 mph) of the B5N.

During the year 1937, both airplanes were tested, with the IJNAS' high command divided between the two. On one hand they liked the good flying characteristics of the B5N, but on the other, they saw it as a very progressive machine, as it had many new characteristics for naval bombers of the time, such as retractable landing gear. So, in late 1937, they IJNAS' high command opted to adopt both designs under the same denomination, of "Type 97 Deck Attack Aircraft of the Fleet". To distinguish both bombers, "Type 97 Model 1" was the B5M and "Type 97 Model 2" was the B5N. 

Unfortunately for Mitsubishi, Nakajima was able to fix the problems of the earlier models of the B5N, while Mitsubishi didn't as they were more concentrated on improving the A5M and designing the A6M, therefore, the B5M was discontinued with only 125 machines having been built between 1936 and early 1941.

The B5M1 (an improved model with a new engine, from 1939) was powered by the Mitsubishi MK8D Kinsei-43 radial engine which, in its newest models, had a theoretical power of 1.080 hp, raising this way its top speed to 381 km/h (234 mph), making it faster than the B5N. However, the IJNAS still decided in favour of the B5N.

The first combat unit to be equipped with the B5M in late 1938 was the newly formed Suzuka Kokutai, based in Eastern Japan. This unit undertook the task of training and evaluating the B5M. 

Contrary to popular belief, the B5M was not deployed to China, as every machine was deployed in combat training units in mainland Japan and, in early 1941, they were assigned as follows:

• Oita Kokutai: 45 units
• Usa Kokutai: 63 units
• Omura Kokutai: 16 units

All those units were deployed at Kure Naval Base, in Tokyo and carried out anti-shipping patrols over the Pacific Ocean, after Pearl Harbour. 

As the IJNAS was in need of every aircraft they could count on, the B5M was rushed to many front-line units, so many B5Ms were assigned in early 1942 to the 33rd Kokutai which took part in the battle of Celebes Island, in the Dutch East Indies. It is not known the exact number of machines that served with the 33rd Kokutai, but by the time that unit was re-organized as the 932th Kokutai, in the summer of 1943, there were still many B5Ms active. 

One of them became famous when, at the hand of Captain Kino, rammed the leader of a formation of American B-24 bombers that bombed the city of Makassar.

From July to October 1942 some B5Ms were assigned to the escort-carrier Un'yo, serving in the area of Truk Atol. It seems too that some machines were retrofitted with forward-firing machine guns, however, as the war went on, the usage of both the B5M and the B5N decreased and, apart from a sporadic anti-submarine patrol, the B5M wasn't used. 

The last known usage in combat of a B5M was during the Kamikaze attacks in Okinawa during April-May 1945. 

Sources:

1. http://www.airwar.ru/enc/bww2/b5m.html (translated)

2. https://en.wikipedia.org/wiki/Mitsubishi_B5M

3. https://www.skytamer.com/Northrop_1933(Gamma5D).html (for the Northrop 5A)

4. https://www.valka.cz/Micubisi-B5M1-Mabel-t30172

Mitsubishi J2M Raiden, part two

Raiden's performance improvement was focused on fitting the type with a turbo-supercharged engine. The first prototype of this variant was powered by the Mitsubishi Kasei 23hei (AKA Kasei 23a) radial engine rated at 1.820 hp, fitted with the company's own supercharger. The prototype used J2M6's fuselage with two cannons fitted aft of the cockpit. The 20 mm cannons fired upwards, in an oblique way, aimed at seventy degrees, just like the German Schräge Musik system. This version was intended to be used against B-29 bombers that operated at altitudes beyond reach of other Japanese fighters.

The second prototype of this version was powered with the same engine but it featured a different supercharger, this time made by Dai-Nijuichi Kaigun Kokuso (21st Aircraft Arsenal of the Navy) at Sasebo, Japan. This prototype was longer than its predecessor and was also equipped with modified engine cooling gills. It received the designation of J2M4kai Model 32kai and was converted by Yokosuka.

Only two prototypes were made of the J2M4 because of problems with the turbo-superchargers, rendering the mass manufacturing process impossible. According to documents captured by American troops, only one prototype was completed, while the other one was a regular J2M3 converted to a supercharger version.

The next version, J2M5 Model 33 was also going to be a high altitude fighter. This version was tested with a new Mitsubishi Kasei 26 engine (fitted in J2M2 airframes) rated at 1.820 hp. It's not possible to tell if the new cockpit frame and the additional flat profile of the upper fuselage in front of the windscreen was first adopted in this variant or in the J2M6, which was developed in parallel. The production variant, of which a total of 34 airplanes were made between May 1944 and August 1945 in Nagoya (though, according to other sources the total number was 43), was powered with the Mitsubishi Kasei 26ko engine fitted with a three-stage centrifugal supercharger. This feature made the J2M5 the fastest Raiden version as it reached a top speed of 615 km/h (382.143 mph) at 6.800 m (22.3097 feet) high. 
One of the J2M5 was shown in surviving photos armed with two 30 mm Type 5 cannons instead of the usual 20 mm ones.

It's also feasible that, due to limited availability of the Kasei 26 engine, some J2M5 airframes were fitted with the Kasei 23ko engine, making it similar-looking to the J2M6.

The last version, the J2M6 Model 31, looked on the outside like a combination of the J2M3 airframe with the J2M5 cockpit. This version was probably tested using the J2M2 airframe with the new cockpit and the flat fuselage top portion in front of the windscreen. Two prototypes were built between June 1944 and February 1945, but one was converted to the J2M4 standard. This variant appeared before the J2M4 and the J2M5, in spite of its numeration, and was developed in parallel, hence the usage of the Mitsubishi MK4C engine.

There were also some projected variants, that were never completed, like the J2M6ko Model 31ko, which was going to use the J2M3ko airframe combined with the J2M3 cockpit. The J2M7 Model 23 was under development and was going to have the J2M3 airframe, but powered by the Kasei 26ko engine. 

There are also mentions to a J2M8 variant which, apparently, was going to have a cut-down rear fuselage and an all-round vision canopy, similar to the of the A6M Zero. 

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_J2M

2. Mushroom Model Magazine - Yellow Series 6110 - Mitsubishi j2M Raiden 'jack'

3. https://www.valka.cz/Micubisi-J2M-Raiden-Jack-t28908

Mitsubishi J2M Raiden, part one

 

The Mitsubishi J2M Raiden was designed by Jiro Horikoshi, the creator of the Mitsubishi A6M Zero to meet the 14-shi official specification calling in 1939. This specification called for a strictly local-defense interceptor, to defend against high-altitude bomber raids. To meet that requirement, the proposed fighter had to rely on speed, climb performance and armament sacrificing maneuverability. The J2M was a sleek, but stubby aircraft with its oversized Mitsubishi Kasei engine buried inside a long cowling and cooled by an intake fan which was connected to the propeller with an extension shaft.

Work on the project began in March 1940 and, back then, it was very innovative by Japanese standards. It featured a low wing with symmetrical airfoil and slotted flaps with a very low cockpit, to minimize drag. The prototype was powered by a single 1.460 hp Mitsubishi Kasei radial engine mounted in a very slim cowling with a small air intake. This, forced the designers to use a fan to achieve proper cooling. 

All those innovations resulted in serious delays in work on the prototype. Furthermore, with Horikoshi concentrating on development of the A6M Zero, Kiro Takahashi, had to take the lead on the development team, remaining in overall control of the project.

It wasn't until March 1942 that the prototype was completed and the first flight, from Kagamigaura airfield, in Chiba, Japan, took place on 20th May. A total of 8 development prototypes were built.

The J2M2 Model 11 was the first production version, which flew for the first time in October 1942. It featured a redesigned cockpit and a Kasei engine with better cooling system and individual exhausts. A total of 131 machines (155 according to other sources) of this variant were manufactured (which were also heavily field-modified to reduce engine vibration) between October 1942 and 1943, including the fourth prototype, which was the pattern for production aircraft. 

The J2M3 Model 21 was another version with improved armament. The fuselage-mounted machine guns were discarded in favor of two additional cannons in the wings, making the airplane to be armed with two 20 mm Type 99 Model 1 and two 20 mm Type 99 Model 2 cannons. In order to fit the additional cannons, the wings had to be strengthened. It also featured improved armor protection. All those changes made a heavier airplane, with the subsequent performance decrease. When the new framed cockpit of the J2M6 was tested, some J2M3 were retroactively fitted with that new cockpit frame.

It also had a sub-variant, called J2M3ko Model 21ko, which replaced the two wing-mounted Type 99 Model 1 cannons with Type 99 Model 2 cannons placed in underwing pods. Twenty-one machines of this sub-variant were built.

In total, counting all sub-variants, 307 J2M3 were manufactured (438 according to other sources) by Mitsubishi at Nagoya and Suzuka and Koza Naval Aviation Workshop from February 1944 to July 1945.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_J2M

2. Mushroom Model Magazine - Yellow Series 6110 - Mitsubishi j2M Raiden 'jack'

3. https://www.valka.cz/Micubisi-J2M-Raiden-Jack-t28908

Mitsubishi G4M, part four

 

The Mitsubishi G4M2 was the replacement variants of the G4M1. The first prototype of the G4M2 flew for the first time in December 1942. It differed from the previous G4M1 in being powered by two Mitsubishi MK4P 'Kasei' radial engines rated at 1.775 hp, driving a four-bladed propeller and capable of full feathering function. Its main wings were also redesigned with LB type laminar flow airfoil and widened tail horizontal stabiliser wing area. All those changes increased type's maximum speed and service ceiling. Main fuel tanks were enlarged, so maximum range was increased too. 

Various sub-variants were made:

• G4M2 Model 22: The main production model. It was introduced in July 1943 and, from 65th aircraft onwards, bulged bomb bay doors were introduced. An optically flat panel in the nose cone, was also featured from 105th aircraft onwards. The total number of produced machines is unknown, as sources vary, but it's placed between 816 and 839.
• G4M2 Model 22 Ko, AKA Model 22A: A sub-variant equipped with a Type 3 Ku Mark.6 search radar and armed with 20 mm Type 99 cannons in the lateral positions.
• G4M2 Model 22 Otsu: Another sub-variant, this time the gun in the dorsal turret was a Type 99 Model 2. 
• G4M2a Model 24: A variant equipped with uprated Kasei MK4P engines, which delivered up to 1.800 hp of power, and bulged bomb bay doors to carry a larger payload. It also had a carburetor air intake on top of the engine cowling. A total of 514 G4M2a Model 24 were manufactured, though that number is not completely certain. The prototype flew for the first time on 31st May 1944. 
• G4M2a Model 24 Ko: Same armament as G4M2 Model 22 Ko.
• G4M2a Model 24 Otsu: Same armament as G4M2 Model 22 Otsu
• G4M2a Model 24 Hei: A modified Model 24 Otsu with a single 13.2 mm Type 2 machine gun placed in tip of the nose cone. Radar antena was also placed above nose cone.
• G4M2b Model 25: A experimental version fitted with MK4T-B Kasei engines, rated at 1.820 hp of power.
• G4M2c Model 26: Another experimental model fitted with the same engines as the G4M2b, but with superchargers added.
• G4M2d Model 27: Yet another experimental model, this fitted with another variant of the Kasei engines.
• G4M2e Model 24 Tei: A special modification made to transport a Yokosuka MXY-7 Kamikaze airplane. It featured armoured cockpit and fuel tanks. The exact number of converted is unknown, but it must've been a minimum of 65 and a maximum of 70 between 1944 and 1945. 

There were also some non-flying decoys of the G4M2, which received the name of MXY11.

The next main variant of the G4M, was the G4M3. This version was a redesigned G4M2 with self-sealing fuel tanks, improved armour protection and a redesigned tail turret, with a gunner's compartment similar to that present in the Martin B-26 Marauder. Wings were also redesigned and the horizontal tailplane was given dihedral. It was armed with two 7.7 mm (0.303 in) Type 92 machine guns in nose cabin, and both side positions, plus one 20 mm Type 99 cannon both in dorsal turret and tail. The first prototype flew for the first time on 1st January 1944 and it entered production in October. It was produced until August 1945, when Japan surrended and a total of 60-65 machines were built. Most of them featured 20 mm Type 99 cannons at the sides, instead of machine guns.

After the loss of Okinawa, the G4M was the main land-based bomber of the Imperial Japanese Navy (IJN). Most of them were assigned to the 20th Kokutai, which included the Testing Air Group, which was equipped in 1944-1945 with the latest G4M3 Model 34 and 36, though these arrived too late and too little to have any impact in the course of the war. 

From November 1944 to January 1945, G4Ms were the main type of aircraft used by the Japanese to strike the Mariana Islands. Plans to use converted G4Ms to land commandos on the islands were developed in mid-1945 and cancelled later, due to the end of the war.

Two de-militarized G4Ms carried the first Japanese surrender delegation on the first leg of their flight to Manila. They were painted in green, with green crosses and were escorted by two P-38 Lightnings. 

The intended successor of the G4M was the Yokosuka P1Y Ginga, however, due to production problems, the changeover was just began when the war ended.

Sources:

1. https://en.wikipedia.org/wiki/Mitsubishi_G4M

2. https://www.valka.cz/Micubisi-G4M2-22-Betty-t8550

3. https://www.valka.cz/Micubisi-G4M2a-24a-Betty-t81394

4. https://www.valka.cz/Micubisi-G4M2e-Betty-t35059

5. https://www.valka.cz/Micubisi-G4M3-34-Betty-t29176