Mitsubishi 1MF1

In order to manufacture aircrafts and automobiles at the Japanese city of Nagoya, the Japanese shipbuilding company Mitsubishi Shipbuilding and Engineering Co. Ltd. set up a subsidiary company called Mitsubishi Internal Combustion Engine Manufacturing Co. Ltd. back in 1920.
Soon after it received a contract from the Imperial Japanese Navy to design, develop and manufacture the three types of aircraft that should operate from aircraft carriers (Akagi and Kaga), a fighter, a torpedo bomber and a reconnaissance aircraft. To design and produce those airplanes, they hired Herbert Smith, former designer at Sopwith Aviation Company who designed the famous Sopwith Camel, to assist in the design of those aircrafts, he brought Jack Hyland to Japan plus a team of other six British engineers.
The fighter designed by them received the company designation of Mitsubishi 1MF1 (Mitsubishi Fighter 1) and received the official designation of Navy Type 10 Carrier Fighter (referring to the year it was designed, 1921, the 10th year of the Taisho period) by the Imperial Japanese Navy and flew for the first time in October 1921.
It was a single-seat, single-bay biplane with unequal span wings and made entirely out of wood. It was powered by a single 300hp Mitsubishi Hi engine which was a license-built Hispano-Suiza 8. It was fitted with a claw-type arrestor gear to be used with British-style fore and aft arrestor cables and was armed with two Vickers 0.303in placed in the upper fuselage decking.
Only one prototype was built of the 1MF1 variant, as they quickly switched to other engines. However this first prototype (of which only one exemplar was built) was accepted into service with the Navy and served until 1927 operating from the Akagi carrier first and then being relegated to the shore base of Kasumigaura, North-East of Tokyo.

Sources:
1. https://en.wikipedia.org/wiki/Mitsubishi_1MF
2. https://forum.valka.cz/topic/view/33675
3. Salamander Books - The Complete Book of Fighters

Kochyerigin DI-6

The Kochyerigin DI-6 was a Soviet two-seat biplane manufactured in the USSR during the late 1930s.
It was designed and developed at TsKB (hence its internal designation of TsKB-11) as a fighter capable of performing ground attack missions when fitted various types of weaponry. Initially it was going to be powered by a liquid-cooled V12 engine but, due to problems with its development, the Wright R-1820 radial one was chosen instead. It flew for the first time on 30th September 1934 and testing began in early 1935 with state acceptance trials taking place between May and November.
In spite of some structural weaknesses that were discovered during those trials, the type was ordered into production and deliveries to the Soviet Air Force began in spring 1937. Some of the problems encountered, like excessive vibration and a poor field of view for the rear gunner, were never fixed, and the various fixes rendered the aircraft heavier, adding around 160 extra Kg (350lb). It was produced until 1939.
It was a conventional single-bay biplane of mixed construction with cable-retracted main landing gear and was powered by a single Shvetsov M-25 radial engine which yielded 700hp of power. It was armed with two 7.62mm (0.3in) ShKAS forward-firing machine guns placed in the wings and another ShKAS placed in the observer's position. It could carry up to 40Kg (88lb) of bombs.
The pilot and the tail gunner sat in tandem cockpits with the pilot's one open and the gunner's one partially closed. To increase the rear gunner's arc of fire, the rear cockpit was set lower in the fuselage than the pilot's.
Apparently some sources claimed that the type saw combat in the Battle of Khalkin Gol against Japan during May to September 1939, and even in the Winter War against Finland in November 1939. However, there isn't any conclusive evidence of the type taking place in any of the battles as it was deemed obsolete by mid-1940.

Sources:
1. https://en.wikipedia.org/wiki/Kochyerigin_DI-6
2. Salamander Books - The Complete Book of Fighters
3. https://forum.valka.cz/topic/view/143262

Messerschmitt Bf.110C, German users, part one

The Messerschmitt Bf.110, often mistakenly known as the Me.110, was a twin-engine heavy fighter (Zerstörer) anf figther-bomber developed in Germany during the late 1930s.
It was armed with two 20mm MG FF cannons, four 7.92mm MG 17 machine guns and one 7.92mm MG 15 machine gun, or, in late variants, twin-barreled MG 81Z for defensive purposes.
Development work on an improved type, the Messerschmitt Me.210 started before the beginning of the war, but its aerodynamical problems hindered it considerably, pushing the Bf.110's operational history until the end of the war alongside its replacements, the Me.210 or the Me.410 (which was a much improved version of the Me.210).
The Bf.110 enjoyed a considerable success early in the war, during Polish and Norwegian campaigns and during the Battle of France. Its main weakness was its lack of agility once in the air, but it could be mitigated with the correct tactics. That weakness was oftenly exploited by the Royal Air Force during the Battle of Britain, when the Bf.100 was flying as a close escort for German bombers.
When the Royal Air Force began to target German soil with night bomber raids, some Zerstörer units were redeployed and re-trained as night fighters, role which the aircraft proved to be well suited for. In other theatres of operations, like North Africa, Mediterranean and Eastern front, it acted successfuly as an air-superiority fighter and strike aircraft. It also defended German soil against raids of USAAF's 8th Air Force, until they changed tactics making the Bf.110 increasingly vulnerable to American aerial supremacy during 1944.
During Balkans and North African campaigns, as well as in the Eastern Front, it provided valuable close air-support as a potent fighter-bomber and later in the war it acted as a formidable radar-equipped night-fighter which became the main night-fighter of the Luftwaffe. Most of the German night fighter aces, flew the Bf.110 at some point in their careers, and the top night ace of all time, Major Heinz-Wolfgang Schnaufer flew it exclusively and claimed 121 victories in 164 combat missions.

Sources:
1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_110
2. Salamander Books - The Complete Book of Fighters

Messerschmitt Bf.110C - Foreign Users

The Messerschmitt Bf.110C was used by many foreign users:

• United Kingdom: At least one Bf.110C-5 was captured by the Royal Air Force and was assigned to the famous No.1426 (Enemy Aircraft) Flight of the Royal Air Force, which evaluated captured enemy aircraft. They were based at Collyweston, in Northamptonshire and by 1944 it was still in service with such unit. 
• Italy: When the Regia Aeronautica formed night fighter units in 1942, they realized that they lacked competent night fighters, so they bought various second-hand Bf.110C from the Luftwaffe. They were assigned to the 1º Centro Sperimentale (1st Experimental Unit) at Guidonia test centre in Lazio in order to train pilots in night flying conditions during summer 1942. When the training was over, they were assigned to the 60º Gruppo (60th Squadron) in the 41st Stormo (41st Wing). They operated from Lonate Pozzolo, in Lombardy. In September 1943, when Italy signed the armistice, the units were disbanded and the Bf.110C were taken back by the Luftwaffe.
• Romania: The Royal Romanian Air Force received some Bf.110C when they formed the Escadrila 51 Vánátoare de noapte (51st Night Fighter Squadron) which was trained in night flying conditions using outdated Heinkel He.112 fighters during 1943. The Squadron was integrated into the Luftwaffe NJG.6 as the 12./NJG.6 and took part in the aerial defence of Romania during 1943 when the USAAF launched the Operation Tidal Wave, the bombing of Romania's petroleum fields. They were active until 1944 when Romania switched sides and the squadron was disbanded and the remaining aircrafts (the squadron had sustained heavy casualties) were taken back by the Luftwaffe.
• USSR: Apparently the Soviet Air Forces bought at least one Bf.110C-4 for evaluation purposes in Autumn 1940. It most probably served as inspiration for the Petylakov Pe-3 and the fate of the Soviet Bf.110C is unknown.
• Kingdom of Yugoslavia: When the Axis invaded Yugoslavia in April 1941, the Royal Yugoslavian Air Force managed to capture at least one Bf.110C which was quickly repainted in Yugoslav colours and used most probably for propaganda reasons. After the fall of Yugoslavia it's fate is unknown, but it was most probably either taken back by the Luftwaffe or destroyed.

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_110#Operational_service

2. https://www.rumaniamilitary.ro/aviatia-militara-in-al-doilea-razboi-mondial-suedia-vs-romania-partea-a-iii-a (translated)

3. Salamander Books - The Complete Book of Fighters

Mitsubishi 1MF10

Back in 1932, the Imperial Japanese Navy issued a specification both to Nakajima and Mitsubishi to find a replacement for the Nakajima A2N which was their main carrier-borne fighter.
Breaking with the biplane tradition which had been the rule until that same moment, both companies submitted monoplane designs with Nakajima submitting a navalized version of their Army Type 91 fighter which was already in service with the Imperial Japanese Army.
Mitsubishi assigned the design of its contestant to a team led by Jiro Horikoshi (the same designer of the mighty A6M Zero) who eventually created the first low-wing cantilever monoplane to be designed in Japan, the Mitsubishi 1MF10.
The Mitsubishi 1MF10 (AKA Mitsubishi Experimental 7-Shi Carrier Fighter) was made entirely out of all-metal with a monocoque duraluminium fuselage, with duraluminium wing structure covered in fabric, with an open cockpit. It was powered by a single Mitsubishi A4 14-cylinder air-cooled radial engine which yielded 780hp (580Kw) of power which drove a two-bladed wooden propeller. It had a fixed undercarriage, both main and tailwheel.
The first prototype, with the internal company name of Mitsubishi Experimental 7-Shi Carrier Fighter, flew for the first time in March 1933 and the first prototype was destroyed shortly later, in July 1933, due to a broken tail during diving tests, although the pilot successfully jumped out of the cockpit by parachute. The second prototype, which had a slightly modified undercarriage, with the main wheels and undercarriage legs faired into streamlined spats, was also destroyed in a crash when it entered an uncontrolable dive spin in June 1934 when it was being piloted by Motoharu Okamura who bailed out in time to save his life but at the cost of four fingers, jeopardizing that way his career as fighter pilot.
Although the design was advanced for its time (it was comparable to the American Boeing P-26), it wasn't accepted by the Imperial Japanese Navy because it had poor handling and it didn't meet the requirements of the specification. However, it did form the basis for more advanced designs as Horikoshi used elements of it (like the box-spar) in the later successful design like the Mitsubishi A5M fighter which had similar layout.

Sources:
1. https://en.wikipedia.org/wiki/Mitsubishi_1MF10
2. https://en.wikipedia.org/wiki/Motoharu_Okamura
3. Salamander Books - The Complete Book of Fighters

Blackburn B-25 Roc

On 31st December 1935, the British Air Ministry, issued an specification named O.30/35 for a carrier-based turret-armed fighter. Blackburn presented a fighter variant of their Blackburn Skua dive bomber, of which two prototypes were ordered for the Fleet Air Arm earlier that year. Boulton Paul presented the P.85 design which was basically a navalized version of the Boulton Paul Defiant turret fighter. Although the Sea-Defiant was expected to be 85mph (137km/h) faster thanks to its engines, the Roc was chosen.
The Roc was a copy of the Skua. It was a two-seat low-wing cantilever monoplane made entirely out of metal equipped with a retractable undercarriage and featuring foldable wings to make it easier to storage it in aircraft carriers. It was powered by a single Bristol Perseus engine which yielded 890hp (664Kw) of power and drove a three-bladed propeller. It was armed with the same type of turret that the Defiant was armed with which had four 0.303in (7.7mm) Browning Machine guns and had the same underwing bomb racks the Skua had, which allowed it to carry eight 30lb (14Kg) of bombs.
On 28th April 1937 the Roc was awarded the contract and an order of 136 aircrafts was placed by the Air Ministry but, as Blackburn was already full on the Skua and the B-26 Botha bomber, they sub-contracted production to Boulton Paul, at Wolverhampton.
The first flight took place on 23rd December 1938 and showed acceptable handling (better than the Skua) but with poor performance with a top speed of only 223mph (359km/h). Due to that performance, it was suggested by the Fifht Sea Lord (the commander-in-chief of Naval Air Services) Alexander Ramsay that the Roc had to be abandoned. Anyway, its production was allowed to continue as cancellation would disrupt Boulton Paul's production too much. Instead plans were made to adapt the aircraft for target-towing.
It was required not only to be a carrier fighter but also to be a floatplane, so a conversion kit with the floats from a Blackburn Shark was made but it proved to be unstable and in December 1939 it crashed when being tested at Helensburg Marine Aircraft Experimental Establishment where it was take in September 1939. A larger ventral fin was fitted to solve stability problems, the floats hindered performance too much with top speed falling to only 193mph (311km/h) and plans to form a floatplane Roc Squadron were discarded.
It equipped however two Fleet Air Arm squadrons, the 800 and 803 late in 1939 with three or four Roc supplementing the Skuas. When 803 Naval Air Squadron was rebased to Northern Scotland, to provide aerial defense for Scapa-Flow naval base, the Rocs proved to be ineffective being described as a "constant hindrance" and eventually replacing all their Rocs by Skuas.
A small number of them saw action during the Allied campaign in Norway when some of them were assigned to 800 and 801 Naval Air Squadrons on board of HMS Ark Royal where they carried out pointless combat patrols over the fleet, showing inadequate performance against German aircrafts.
They operated also over France during spring/summer 1940 at the evacuations of Allied forces, which is when the most probable sole aerial victory of the Roc happened. It was on 28th May 1940 when a Roc on patrol belonging to the 806 Naval Air Squadron flown by pilot Midshipman A.G. Day and two Skuas intercepted five German Junkers Ju.88 attacking a convoy off Ostende, in Belgium. The Roc flew underneath the Germans, while the Skuas attacked from above. Day's Skua shot down a Ju.88 and returned safely to RAF Detling, in Kent. Some Rocs of the 801 Naval Air Squadron also strafed and dive-bombed German E-boats at Boulougne harbour on 12th June damaging several of them and later, on 20th June they were used to bomb gun emplacements at Cap Gris Nez in Calais, France.
It was relegated to air sea rescue and target towing. Number 2 Anti-Aircraft Co-operation Unit at Gosport received 16 Rocs to replace the Blackburn Shark in June 1940. Some of them were sent to Bermuda to be part of the anti-air defences there and were in service until June 1943. The last four Rocs based at HMS Daedalus in Gosport, survived until late 1944 still being airworthy and with their turrets being used for anti-aircraft defence.
The Finnish Air Force ordered 33 aircrafts directly to Blackburn Aeroplane and Motor Company Ltd. and they were even sailed, but they didn't go beyond Dyce, in Aberdeen as deliveries were cancelled due to the Winter War and were absorbed into Fleet Air Arm's order.

Sources:
1. https://en.wikipedia.org/wiki/Blackburn_Roc
2. http://www.britishaviation-ptp.com/b/blackburn_skua_roc.html