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. Part fifteen. *FINAL POST*. The Blenheim during late war.

 

Production of the Bisley commenced at some Rootes plant in October 1941 and in November the Air Ministry changed its denomination to Blenheim Mk V on the basis that a different name for an aircraft with the same basic outline could lead to misleads. The original contract numbers ordered 1.195 total aircraft, though its number was eventually reduced to 942. The final production aircraft was delivered to from the Rootes Ltd. factory at Blyth Bridge, Staffordshire in June 1943.

The Mk V saw service for the first time in North Africa when, in the context of Operation Torch (the Allied invasion of French North Africa), four Royal Air Force (RAF) squadrons of No 236 Wing (Nos 13,18,114 and 614 to be more precise) were selected to transition to the Mk V. This change did not seem to please the crews of those squadrons as other RAF bombing squadrons were in the process to convert from Mk IV to the Douglas Boston or the De Havilland Mosquito which had better reputation. In November 1942 the four aforementioned squadrons were deployed to Camrobert airfield, in Algeria, at around 200 miles from Bizerte, their main target. 

In order to cut the risks of unescorted missions, the squadrons soon moved to forward airfields. On 17th November No 18 Squadron was completely destroyed, as an effective unit, during a ground attack mission when the twelve aircraft formation was attacked by Bf.109 belonging to JG 2. The whole attack took just five minutes. 

Blenheim Mk V units in North Africa overtook the Ground Support role by bombing enemy troop concentrations, supply lines and airfields for the next five months until the Axis surrendered in May 1943. By the end of the Tunisian Campaign, Nos 13 and 614 squadrons still operated the Mk V, but Nos 18 (reformed) and 114 were converted to the Douglas Boston. No 13 kept the Mk V for coastal patrols over Tunisian shores until late 1943, when they were converted to the Lockheed Ventura. No 614 squadron, on the other hand, was rebased to Sicily, where they flew the Mk V until February 1944 when the squadron was disbanded.

In the Middle East, two more RAF squadrons saw service with the Mk V. Nos 8 and 244 were based in Aden, tasked with the surveillance of the Red Sea between 1942 and 1944. In the Far East Theatre (FET), the four squadrons of No 221 Group, based in India, and later in Burma, operated the Mk V for attacks against Japanese targets. However, by the fall of 1943 they all were converted to more modern aircraft. 

In the United Kingdom, some Mk V remained active with Meteorological Flights and Operational Training Units until as late as July 1945, though most of the Blenheims were retired from the active inventory in mid-1944, ending its career with the RAF.

Sources:

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

2. Signal Squadron - Aircraft In action 88 - Bristol Blenheim in Action

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

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

Bristol Blenheim, part fourteen. The Blenheim in 1942.

 

The Blenheim Mk IV saw active service in the North African Theatre of Operations. In fact, by the date Italy declared war on Britain on 10th June 1940, only one squadron, No 113, was completely equipped with the Mk IV, however, by the end of the year, around 100 Blenheim Mk IV arrived to re-equip other Middle East squadrons. In order to avoid enemy-controlled aerospace, they were shipped to Takoradi, in the British Gold Coast (nowadays Ghana), where they were re-assembled and ferried for over 4000 miles across central Africa to Egypt. 

Their initial operations in the Mediterranean Theatre of Operation (MTO) were conducted by Nos 45 and 55 Squadrons, though some Mk IV saw limited action in Greece, before British evacuation. During the Iraqi revolt in April 1941, No 203 squadron, based at RAF Habbaniya (Iraq) the Mk IV flew some sorties against the pro-Axis revolt that took place there. Shortly later, they took part in the Syria-Lebanon campaign against Vichy France, until the colony gave up in July. 

During the following fifteen months, the Blenheim Mk IV units were involved in providing ground support for the British Eight Army in their engagements against the Deutsche Afrika Korps (DAK) and the Italian units. 

It was during those months that many squadrons of No 2 Group were sent from Britain to Malta to defend the island from Axis aerial bombing. Blenheims based there and, mainly, in Egypt, employed tactics similar to those used in the Channel Stop operation, inflicting thus, heavy losses in Axis maritime shipping. In fact, during late 1941, more of 65% of Axis merchant shipping in the area was sunk, however, with a high cost for Royal Air Force's Blenheim squadrons present in the MTO. 

A field modification for the Mk IV was made by adding a Vokes air filter to the carburetor intake to prevent the abrasive effect of sand and grit on the engine. 

By late February 1942, however, there were few Mk IV units in North Africa as most of them were needed in the Far East Theatre (FET) after the Japanese attack on Pearl Harbor. 

The remaining units transitioned to the Douglas Boston.

The Mk IV was used in the FET. In January 1942 two squadrons, Nos 84 and 211 were rebased from the Middle East to Sumatra (Dutch East Indies), to be part of the weak No 225 (Bomber) Group. There they were joined by some surviving Mk IV from No 34 Squadron which managed to evacuate Singapore in time. They were rebased to Palembang, where they performed convoy escort, reconnaissance and bombing missions against their former airfields in Malaya. On 15th February 1942 an all-out attack was launched against the Japanese invasion fleet off Sumatra. They were, however, not very successful as the available units and personnel were not enough, although they managed to sink some transports.

Later, on 18th February, the few remaining Mk IV were rebased to the island of Java, with the Blenheims of No 211 Squadron being absorbed into No 84. There, they were employed in harassing missions against the Japanese invasion fleet until 1st March, when the very few remaining Blenheims were either destroyed on ground or captured by the Japanese. 

That wasn't the end for the Blenheim the FET. In April 1942 the Japanese sent a carrier task force to attack Royal Navy's base in Ceylon. On 5th April, a force consisting on 125 Aichi D3A 'Val' bombers and Nakajima B5N escorted by Mitsubishi A6M Zeroes, attacked the British base destroying some Royal Navy's ships. After the raid, some Blenheim Mk IV of No 11 Squadron flew the area searching for the Japanese task force. The task fleet was eventually located on 9th April and eleven Blenheims were sent to strike on the Japanese. On the attack, two aircraft aborted due to engine problems and, from the remaining nine, five were lost to either anti-air fire or fighters. On 11th April the Japanese task force retired from the Indian Ocean, putting an end to their raid. 

The Blenheim Mk V was a bomber development of the cancelled Bristol Bisley. The Mk V featured a strengthened structure, pilot armour, interchangeable nose gun pack or bomb aimer position, a better turret, armed with two 0.303 in Browning machine guns and it was powered by a better version of the Bristol Mercury engine, yielding 950 hp of power. It was used mainly in the MTO and the FET. 

Sources:

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

2. Signal Squadron - Aircraft In action 88 - Bristol Blenheim in Action

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

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

Bristol Blenheim, part thirteen. The Blenheim Mk.IVF and more operational history.

 

The Blenheim Mk.IVF was, like the Mk.IF, its predecessor, the fighter variant of the Mk.IVF. It differed from the regular Mk.IV in having a gun pack installed in the bomb bay. This gun pack varied slightly from the one of the Mk.IF in being deeper in order to give the guns a clearer field of fire under the nose of the Mk.IV. The first Royal Air Force's (RAF) unit to be equipped with the Mk.IVF was No 600 Squadron, tasked with the night aerial defense of London. Just like it happened with the Mk.IF, the Mk.IVFs were also modified to fit an Airborne Interception (AI) radar. However, due to the poor performance of the radar and the poor performance of the Blenheim as a fighter, very few German bombers were intercepted. From September 1940 onwards, the Mk.IVF were replaced by Beaufighters and the Mk.IVF were passed on to Coastal Command's service. 

The Coastal Command was, eventually the main user of the Mk.IVF, as it served mainly in the anti-shipping and maritime escort roles. No 235 Squadron was the first squadron to fully transit to the Mk.IVF. They operated from Dyce, Scotland with a detachment deployed in the Shetland Islands. Other Coastal Command squadrons operating the Mk.IVF were No 236, based at Bircham Newton, East Anglia, No 248 at Aldergrove, Northern Ireland and No 254 at St. Eval, in Cornwall. No 254 was almost fully commited to anti-submarine duties, but the other ones performed a wide variety of roles between June 1940 and June 1942. One specific mission involved No 235 Squadron's Mk.IVF shadowing enemy shipping on the Norwegian Coast until a force of Beauforts and Hudsons could assembled to attack. 

Those squadrons based in Southern England performed mainly maritime escort roles for British shipping in the Channel and North Sea. They also acted as escorts for Beaufort and Hudsons. Some Mk.IVFs were also involved in fighter sweeps against German targets on the French shore and also providing air cover for the Air Search Rescue (ASR) operations. For this particular role the Blenheim was well suited thanks to its range, its endurance and its firepower. 

In the Mediterranean Theatre of Operations (MTO) No 203 Squadron was the only user of the Mk.IVF. This unit was based in Aden and was dedicated to the maritime escort role in the Red Sea. During the course of many sorties, some Italian Savoia-Marchetti SM.79 based in Ethiopia were shot down. This Squadron also saw action in Greece before being withdrawn to Egypt where it had its Mk.IVFs replaced with Martin Marylands as a regular bomber squadron.

The failure of both Mk.IF and Mk.IVF as long range fighters was caused by the rapid advance in technology between the year it was designed (1936) and its operational years (1940-1942). It, however, filled the need for a long range fighter/strike aircraft until more adequate aircraft, like the Mosquito, were operational. 

In June 1941 the RAF employed a new tactic of attacking German targets in France with Blenheim under a heavy escort. This operation was codenamed Circus and it involved the Blenheims of No 114 Squadron escorted by nine fighter squadrons. This series of attack began on 10th January and it was expected that German fighters would take the bait allowing British fighters to attack and destroy them. The Germans, however, soon realized the true intentions of the British and turned to stalk and ambush the bombers every time they had the chance. 

During this operation, the RAF's Blenheim unit involved, suffered double the losses inflicted to the Germans, mainly by the fighters of JG 26 which showed themselves capable of facing British raids both in France and the MTO. 

Shortly later, in April 1941 the RAF tried to close the channel to every enemy shipping during daylight. This operation was codenamed Operation Channel Stop and was part of a bigger operation involving raids from the entire North Sea coast since March. Under normal circumstances, these operations would've been taken by the Coastal Command, however, they had their hands full with fighting U-Boat wolfpacks in the Atlantic, so the Blenheims of No 2 Group were tasked with the mission of flying sorties over Holland, Denmark and Norway which were known as 'Beats'. The bombers flew in low altitude to attract anti-air fire of the defending flak barges. This risky role, coupled with the ability of the Luftwaffe to mount fighter patrols, led to high loss rates and the end of Operation Channel Stop in early 1942. Outside this operation, some Blenheims of No 2 Group raided Germany on 4th July 1941 when twelve Blenheims of No 105 Squadron bombed the port of Bremen. They managed to hit their targets at the cost of four Blenheims. On 12th August a force composed fo 54 Blenheims plus escorts flew at low level altitudes to attack two power stations outside Cologne. They caused moderate damage on the targets and ten Blenheims were lost.

The high casualty rates of these actions, coupled with the availability of better twin-engined bomber aircraft such as the Douglas Boston, led to the retirement of the Blenheim from the frontlines in the European Theatre of Operations by December 1941.

In North Africa and the Mediterranean, the Blenheim played a more significant role. In July 1941 it had been recognized that to the increasing intensity of the combats there, additional bomber squadrons were needed. In the second half of 1941 several Blenheim squadrons were based in Malta until early 1942 when they became part of the Western Desert air operations. However, by that time the Blenheim was also already being replaced by more capable types such as the Vickers Wellington, Martin Maryland or Martin Baltimore, and many units were sent to the Far East as tensions with Japan were growing there.

When War was waged on the Far East, on 8th December 1941 (local date) the RAF had stationed two Blenheim Squadrons in Malaya; Nos 34 and 62 and one, No 60 in Burma. When the War broke out, most of No 60 Squadron was located at Kuantan, in Malaya, undergoing some training, with barely no aircraft left in Burma. The majority of the Blenheims were destroyed on ground during the first day of combat as a surprise Japanese attack on Alor Star destroyed eleven of the twelve Blenheims of No 60 Squadron. The lone remaining Blenheim took off and attacked Japanese landing barges off Singora. For this action the pilot was posthumously awarded with the Victoria Cross. By the end of December No 60 Squadron was rebased back to Burma.

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

2. Signal Squadron - Aircraft In action 88 - Bristol Blenheim in Action

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

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

Bristol Blenheim, part twelve. The Blenheim in 1941 & the Bristol Bisley.

 

A long-range radar-equipped fighter version was also developed, the Blenheim Mk.IF. For this purpose, as we already have seen, around 200 Blenheim Mk.I were fitted with a ventral gun pack containing four 0.303 in (7.7 mm) Browning machine guns. These aircraft were fitted, mostly in 1941, with the Airborne Intercept (AI) Mk.III or Mk.IV radar to be employed as night fighters, making them the first British fighters to be equipped with a radar. The Blenheim was chosen for this purpose as its fuselage was big enough to accommodate the additional equipment and crew member needed for radar operations. 

The initial tests of the AI radar were initially discouraging as the radar operator had difficulties to discern the target on the radar screen as it was hazy and misleading, which made calculations of its position in regards to the other aircraft's almost impossible. Even when the target appeared loud and clearly on screen, the margin error in height and direction was considerable. However, development on the AI radar continued and by late 1940 and 1941 most of those faults were solved.

The first successful interception by a radar-equipped Blenheim Mk.IF took place on the night between the 2nd and 3rd July when an Mk.IF of the Fighter Interception Unit (FIU) based at RAF Ford, in Sussex, shot down a German Dornier Do.17Z bomber. However, the efficiency of night-fighter operations with the Blenheim were the exception instead of the rule. The Blenheim simply wasn't fast enough to make more than one pass on its target and its machine guns were, in most cases, insufficient to destroy an enemy bomber on a single pass. 

During late summer 1940 the Bristol Beaufighter was developed for the night fighter role and during autumn/winter it began to replace the Blenheim as a radar-equipped night fighter. By May 1941 the last Blenheim Mk.IF unit, No 68 Squadron had replaced its Blenheims with Beaufighters putting an end to the Blenheim as a night-fighter. Given their replacement as night fighters and their radars, many were used for night intruder operations over France attacking German bomber bases at night. 

In the Far-East Theatre of Operations, the Blenheim Mk.IF was used by just one squadron, No 27. No 27 was equipped with Mk.IFs in early 1941 and was rebased from India to Singapore, where it was decimated during the Battle of Malaya in early 1942 after flying few sorties. This squadron replaced their Blenheims with Beaufighters.

In the North African Theatre, the No 30 Squadron was based in the Suez Channel Zone during June 1940 and was used as a mixed fighter-bomber squadron. This squadron was later rebased to Greece where it took part in the Greco-Italian War until May 1941 when, after the German intervention, it was rebased to Crete. There this unit was involved in the aerial defense of the Mediterranean island and later replaced its airplanes with Hawker Hurricanes. 

Nine more squadrons were equipped with the Blenheim Mk.IF between 1939 and 1940. However, by mid-1940 most of them had them replaced by more modern aircraft, with the exception of No 219 Squadron, which kept their Blenheim active for many months when every other squadron had replaced their Blenheims.

The Bristol Bisley (named after the shooting competitions held at Bisley, Surrey, was a ground attack conceived variant. This was equipped with a solid nose containing four more Browning machine guns.  The Bisley featured additional armour protection and a modified dorsal turret to fit two Browning machine gun and allow for a 360º angle of fire. The first prototype flew for the first time on 24th February 1941 and was followed by a second prototype. This would eventually be the prototype for the Blenheim Mk.V as, after testing, high level bombing for the Blenheim was preferred.

Sources:

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

2. Signal Squadron - Aircraft In action 88 - Bristol Blenheim in Action

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

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

5. https://www.baesystems.com/en/heritage/bristol-160-blenheim-v-and-bisley

Bristol Blenheim, part eleven. The Blenheim during the Battle of Britain and early Mediterranean campaign.

 

The Bristol Blenheim was armed with a single forward-firing 0.303 in (7.7 mm) Browning machine gun outboard of port engine with a 0.303 in Lewis machine gun placed in a dorsal turret firing to the rear. After the Campaign of France, the Lewis was replaced by a more modern 0.303 in Vickers VGO machine gun. A total amount 1.000 lb (450 kg) of bombs could be carried in the internal bomb bay located at the central part of the fuselage. Like most contemporary British bomber aircraft of the time, bomb bay doors were closed with bungee cords and opened with the weight of the released bombs. As there was no way to predict how long would it take for the bombs to open the doors, bombing accuracy was low. The bomb bay could also be loaded with a hand-operated winch which was part of the fuselage. 

Blenheim-equipped squadrons operated throughout the Battle of Britain, suffering heavy losses, although they never received the publicity that fighter squadrons had. From July to December 1940 Blenheims often raided German airfields in France during both day and night. Most of those raids were unproductive though. However, there were some successes. On 1st August twelve Blenheims were sent to attack the airfields in Haamstede (Netherlands) and Evere (Brussels - Belgium) where they destroyed or heavily damaged three Messerschmitt Bf.109 of II./JG.27 and killing a German ace. Two additional Bf.109 were claimed by Blenheim gunners. On 7th August another successful raid was carried on by a single Blenheim which destroyed one Bf.109 of 4./JG.54, heavily damaged another one and caused light damage to four more fighters.

Some other missions however, were not that successful and had an almost 100% of loss rate among the Blenheims. One of those operations was a raid carried out on 13th August 1940 against a Luftwaffe airfield in Aalborg, Denmark by twelve Blenheims of the No 82 Squadron. On their way to the target, one Blenheim returned early (for this, the pilot was charged, but he was killed later during a mission before a martial court was held), the remaining eleven reached Denmark but were shot down. Five by flak and six by Bf.109s. The Blenheim was also used to carry out reconnaissance missions over Germany and German-occupied lands. In this role, the Blenheim proved to be, again, too vulnerable and slow against Luftwaffe fighters and their casualty rate was high. 

From 5th September 1940 Blenheims began to target German-occupied ports along the English channel, together with heavier bomber types. They also performed anti-shipping patrols, as Coastal Command's strike squadrons were heavily depleted through the second half of 1940. On 11th March 1940 a Blenheim registered as P4852 became the first Royal Air Force's aircraft to sink an u-boat scoring two direct hits on U-31 at Schillig Roads. 

The Blenheim was also extensively employed in the Mediterranean theatre. When Italy declared war in June 1940, there were five Blenheim squadrons stationed in Egypt, three at Aden and one in Iraq. Bombing raids against Italian positions were almost immediate in North Africa, however, operations there and in East Africa were sporadic until late 1940.

During Operation Compass in December 1940 both Blenheim and Wellington squadrons were active during the whole operation bombing both enemy encampments and important strongholds such as Tobruk and Benghazi. Four Blenheim units, squadrons No 11, 30 and 84 and 113 (which was sent to Greece in October 1940) were reinforced by No 211 squadron in March 1941 (which came from Greece). The squadrons operated under extremely primitive conditions and couldn't mount an effective bombing campaign. 

Sources:

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

2. Signal Squadron - Aircraft In action 88 - Bristol Blenheim in Action

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

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

Bristol Blenheim, part ten. The Blenheim during the Battle of France

 

The Blenheim carried a crew of three, pilot, navigator/bombardier and wireless radio operator/turret gunner. The pilot's section on the left side of the nose was so cramped that the control yoke obscured all flight instruments and engine instruments blocked forward view when landing. Most secondary instruments were placed on the left side of the cockpit with basic control items like propeller pitch control were placed behind the pilot where they had to be operated purely by feel. The navigator/bombardier sat alongside the pilot and employed a sliding/folding seat when aiming the bombs. Dual flight controls could be also installed. The wireless radio operator/turret gunner's place was aft of the wing, alongside the aircraft's gun turret. 

The Blenheim saw action during the Battle of France. On 10th May 1940 Germany launched an attack against France through the Netherlands and Belgium, where they clashed with the British Expeditionary Force (BEF). The BEF was moved to forward positions to keep up with Allied's defensive plans, however, a second German offensive through the ill-defended Ardennes region split up both British and French forces. The BEF was under danger of encirclement and was forced to withdraw, being evacuated through the ports of Calais, Dunkirk and many other mores. Those Blenheims units of the Advanced Air Striking Force (AASF) present in France, No 114 Squadron lost most of its aircraft on the ground when nine Dornier Do.17 belonging to II/KG.2 made a surprise attack on their airfield. No.139 Squadron lost seven of nine aircraft during a bombing run made by Messerschmitt Bf.109E fighters of JG.27.

The five Blenheim units of the main Air Component saw a similar fate, just like most of the Great-Britain-based squadrons committed to the French theatre. No 15 Squadron lost six out of twelve Blenheim on 12th May, No 82 lost eleven of the twelve Blenheims sent to attack German positions at Gembloux, Belgium, on 14th May. On that same day, No 110 Squadron lost twelve aircraft at the German salient in Sedan. It was obvious that the defensive configuration of the Blenheim was highly inadequate and the combined firepower of a complete squadron was not enough to discourage enemy fighter attacks. This added up to the fact that the few fighter squadrons available in France were highly dispersed and, even when providing escort for the bombers, they were, generally overwhelmed by superior enemy numbers. The medium altitudes at which the Blenheims made their bombing runs, also deemed them easy targets for ground anti-air fire, so many were lost to flak. 

These factors led to new field modifications aimed to increase the Blenheim's defensive strength, mainly in the form of improving the turret's machine guns by either adding a new one or replacing them. In this context, a new remotely-operated ventral turret was envisioned by Bristol. This, was placed under the nose and could be jettisoned to be used as an escape hatch. 

The Blenheim also lacked self-sealing fuel tanks or crew armour protection, both improvements were added in later versions. Another minor improvement was the inclusion of a rear-view mirror placed on the canopy frame above and ahead of the pilot's line of view. This was accompanied with the inclusion of Perspex bulged blisters on side canopy windows. 

Sources:

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

2. Signal Squadron - Aircraft In action 88 - Bristol Blenheim in Action

3. Hall Park Books - Warpaint 26 - Bristol Blenheim

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