Fairey Gannet, part two

 

The Fairey Gannet was a carrier-borne anti-submarine/strike aircraft that was designed and developed by Fairey Aviation after World War 2.

The Gannet was build as a response to the GR.17/45 Admiralty requirement made in 1945, for which both Fairey (Fairey Type Q, AKA Fairey 17) and Blackburn (Blackburn B-54/B-88) presented their prototypes. 

Initially, the Rolls-Royce Tweed engine was considered, however, Fairey discarded it in favour of the Armstrong-Siddeley Mamba turboprop, the Double Mamba. These engines were mounted side-by-side and coupled through a common gearbox to coaxial contra-rotating propellers with each engine driving its own propeller. Power was transmitted by a torsion shaft engaged through a series of sun, planet, epicyclic and spur gears to give a suitable reduction ratio and correct propeller-shaft rotation. 

The ASMD.1 engine, capable of achieving up to 2.950 hp of power, was equipped in the Gannet AS.1 (first anti-submarine version) and the AS.4 (an improved anti-submarine variant) was powered with a ASMD.3 engine with 3.875 hp of power. The Double Mamba engine could be run with one engine off and its propeller feathered to conserve fuel and extend endurance when cruising. In a traditional twin-engined aircraft, this would create thrust asymmetry, however, this was avoided thanks to the centerline-mounted propellers. Mamba exhausts were placed on each side of the fuselage, at the root of the wing trailing edge. The gas turbine engine could run on kerosene, "wide-cut" turbine fuel or diesel fuel, allowing the Admiralty to discard the dangerous high-octane petroleum spirit required to operate piston-engined aircraft from aircraft carriers. 

Sources:

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

2. https://www.thunder-and-lightnings.co.uk/gannet/history.php

3. Hall Park Books - Warpaint 23 - Fairey Gannet

Fairey Gannet, part one, foreign users

 

The Fairey Gannet was a British carrier-borne aircraft of the post Second World War. It was a mid-wing monoplane with a tricycle undercarriage, a crew of three and a double turboprop engine driving two contra-rotating propellers. 

It was used by many non-British users:

• Australia: The Royal Australian Navy (RAN) decided to purchase the Fairey Gannet in the early 1950s for use on board on the soon to be commissioned HMAS Melbourne (R21) aircraft carrier. Six RAN aircrew went to the United Kingdom in early 1955 to be trained on operating the Gannet at the Royal Navy Air Station (RNAS) Eglinton, in Northern Ireland. 
  Later, two RAN Gannet squadrons, were formed at RNAS Culdrose, in Cornwall, and later, on 23rd August 1955, they were officially formed as 816 and 817 Squadrons. On 8th March 1956 HMAS Melbourne arrived at Glasgow, Scotland and the two Gannet squadrons (24 machines in total) were loaded on board, together with two squadrons of de Havilland Sea Venom fighters and two Bristol Sycamore helicopters for use in the RAN. Then, HMAS Melbourne sailed to Australia and in early May 1956 she arrived in Jervis Bay where the aircraft were unloaded and transported by road to the Naval Air Station at Nowra, in New South Wales. 
  Ten additional Gannets were also acquired to replace losses due to accidents. On 18th August 1958 , one squadron, 817 was decommissioned, leaving 816 squadron the only one to operate the Gannet in Australia. Three Gannet T.2 (dual control trainers) were also purchased in 1957 and one AS.1 was later converted into a T.5 training aircraft, which was operated by 724 and 725 squadrons.
  The Gannets conducted regular exercises on board HMAS Melbourne, in Australian and South-East Asian waters, as well as being part of the Far East strategic reserve, where they were employed for surveillance and reconnaissance duties during the Malayan Emergency and the Indonesian Confrontation. HMAS Melbourne was also part of the escort the fast troop transport ship HMAS Sydney (R17) on her first deployment to South Vietnam in 1965-1966. Fifteen of the thirty-seven purchased Gannets, were lost in accidents and a total of six crew members were killed. After having served for more than ten years, in July 1967 the Gannet was withdrawn from front line service as, by then, they were redundant and were being replaced by either the Westland Wessex helicopter with its dipping sonar and/or Grumman S-2E/G Tracker with its high-tech electronics and anti-submarine equipment.
  Nowadays, some few Gannets are shown as museum aircraft, but most of them were scrapped or re-purposed at Nowra for fire-fighting training.
• West Germany: The Federal Republic of Germany operated the Gannet too. In 1956 the German Federal Armed Forces were created as a member of the NATO alliance. West Germany's naval interests lay mainly in the Baltic Sea and, as Soviet and Warsaw Pact submarines would have to traverse the shallow Baltic approaches to reach the open North Sea, NATO planners assigned West Germany with an important anti-submarine role within the alliance. Britain supplied most of the main equipment of the embryonic Marineflieger (German Naval Air Arm) with 15 Gannet AS.4 and one T.5 ordered in 1956. 
  As time was essential, the aircraft were withdrawn from previous existing Admiralty contracts and pilot conversion training was undertook at White Waltham airfield, in Berkshire during early 1958 and operational crew training was carried out at RNAS Eglinton, where, in order to accelerate crew training a single T.5 was delivered on 6th March 1958 and the Bundesmarine's Gannet Squadron MFG 1/1 was formed two months later. 
  After having been commissioned, the squadron flew to its new home base of Schleswig in late July 1958 where it operated as part Marinefliegergeschwader 1 (MFG 1) on anti-submarine and anti-shipping duties as tasked by NATO's Commander Baltic Approaches (COMBALTAP). The Gannets serving with the MFG 1 they generally used their construction numbers as a permanent identity and were identified within their unit by a two-letter and three figure fuselage code ranging from 'UA+101' (where the letter U indicated the airplane's anti-submarine role and the letter A indicating MFG 1) to UA+115. The T.5 received the unusual figure code of UA+99.
  The squadron was later rebased to Nordholz, in Lower Saxony and transferred to MFG 3 control. Under this new command, the Gannets retained their 'UA' codes instead of the unit's 'UC'. One aircraft, UA+115 was lost to an accident but the remaining Gannets continued to serve with the Marineflieger until their task was taken over by helicopters and the Breguet Br.1150 Atlantic patrol aircraft. The first Br.1150 Atlantic arrived in Nordholz in December 1965 and the Gannets were eventually assigned for storage from June the following year. Switzerland showed some interest to use them as target tows, but as original contract prohibited sale of the aircraft to third parties, nothing came of this. Most of German Gannets were scrapped, but some of them were kept as museum exhibits.
• Indonesia: Indonesia ordered 18 Gannet AS.4 and some T.2 together with ground instruction frames directly from Fairey in January 1959. This came because of Dutch pressures to France to not sell the Breguet Br.1050 Alize as the Dutch foresaw problems with their former colony. However, the UK approved the sale to the Indonesian Air Force.
  Fairey bought back 20 surplus Gannet AS.1 and two T.2s airframe from the Admiralty to fulfill the contract. Those AS.1 were updated to AS.4 standards and some other AS.4 were bought. 
  After undergoing official training at White Waltham, and suffering several delays because of political and military reasons (Indonesia had invaded Western Papua-New Guinea with subsequent clashes with Dutch forces in the region), it wasn't until 18th January 1962 that Indonesian Gannets were shipped to the Asian country. 
  Under Indonesian service the Gannets were used for coastal reconnaissance missions, supporting Indonesian forces moving east through the archipelago. When Malaysia achieved independence in September 1963, Indonesia advanced into North Borneo too and this caused an armed response from Britaim which lasted until 1966. During this period, the West called off every arms trade with Indonesia, and as spare supplies ran off, Indonesian Gannets began to steadily fall. The Indonesian government then turned to the USSR for military help and by 1971 very few Gannets were still in service. The last one was withdraw shortly afterwards and nowadays one is conserved in Indonesian Armed Forces' Museum in Jakarta.

Sources:

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

2. https://www.navy.gov.au/aircraft/fairey-gannet-as14

3. https://www.bredow-web.de/Luftwaffenmuseum/Transport/FAIREY-GANNET/fairey-gannet.html (translated)

4. Hall Park Books - Warpaint 23 - Fairey Gannet

Messerschmitt Me.264 'Amerikabomber'

 

The Messerschmitt Me.264 was a long-range German strategic bomber developed during World War 2. It was intended to be Luftwaffe's main strategic bomber.

Its origins came from Messerschmitt's long-range reconnaissance aircraft project, named P.1061 in the late 1930s, a variant of which was the P.1062, with only two engines, against the P.1061 four engines. However, those two engines were the more powerful Daimler-Benz DB.606 'Power Systems', each comprising a pair of DB.601 inverted V-12 engines. This system was already successfully employed in the Messerschmitt Me.261 long-range reconnaissance aircraft. This engine system was also installed in a variant of the Heinkel He.177A, but it was denigrated by Hermann Göring. In early 1941 six P.1061 prototypes were ordered from Messerschmitt. This order was eventually reduced to three prototypes. 

The progress of the project was initially slow, but when Germany declared war on the United States, after the Japanese attack on Pearl Harbor, the Reichsluftfahrtministerium (RLM - Reich's Aviation Ministry) endorsed the Amerikabomber programme in the spring of 1942 for a very long range bomber capable of reaching the United States' east coast from bases in France or Azores Islands. Proposals were put forward for the Junkers Ju.390, the Focke-Wulf Ta.400, a redesign of the incomplete and never-built Heinkel He.277 and a design study for an extended-wingspan six-engine Messerschmitt Me.264B. The need for six engines was prompted by the inability of German aircraft engine manufacturers to create a 1.5 kW (2.011 Hp) combat-reliable powerplants. As the Junkers Ju.390 was itself a redesign of the Junkers Ju.290 already in use, that design was chosen. This did not mean the abandonment of the Me.264, as the Kriegsmarine (German Navy) separately demanded a long-range maritime patrol aircraft with attack capabilities to replace the Focke-Wulf Fw.200. This was endorsed by an opinion given by Generalmajor von Gablenz in May 1942 about the viability of the Amerikabomber. As a result the two pending prototypes were ordered to be completed as an ultra long-range reconnaissance aircraft.

The Me.264 was an all-metal high-wing four-engine heavy bomber of traditional design. The fuselage was round in cross section and had a cabin in a glazed nose, making for a stepless cockpit with no separate windscreen section for the pilots. This design, common in many German bombers, like the Heinkel He.111, resembled the cockpit of the Boeing B-29, of slightly earlier design. The wing had a slightly swept leading edge and a straight trailing edge. The tail section had double tail fins and undercarriage was a retractable tricycle gear with large diameter wheels on the wing mounted main gear.

Planned defensive armament consisted on four 13 mm (0.51 in) MG 131 and two 20 mm (0.78 in) MG 151/20 cannons distributed as follows:

• Two MG 131 in dorsal turrets, one located just aft the cockpit and another one on the middle section plus two more in waist positions.
• One MG 151/20 remotely operated placed in the tail plus another ventral one, remotely operated too.

Overall, it carried very little armour and relatively few guns, in order to increase fuel capacity and achieve the intended range of 15.000 km (9.321 milles) with an endurance of 45 hours. 

The first prototype, called Me.264 V1 was initially fitted with four Junkers Jumo 211 engines with an engine setting made standard by the Junkers Ju.88A. However, inadequate power from the Jumo engines, forced their replacement on the Me.264 V1 with four similarly unitized 1.676 hp (1.250 kW) BMW 801G engines. In order to provide comfort for the long-range missions, it also featured bunk-beds and a small galley complete with hot plates.

The first prototype, registered as RE+EN, flew for the first time on 23rd December 1942. Trials showed numerous minor faults and handling was found to be difficult. The design had to cope with very high wind loading rates, when fully loaded. Comparable aircraft, such as the B-29, the Heinkel He.277 or the Ju.390 had lower loading. This setback caused poor climbing performance, loss of manoeuvrability, stability and high take-off and landing speeds. The first prototype had no armour on the engines nor defensive armament, but the following prototype, Me.264 V2 had armour on the engines while the third prototype, Me.264 V3, was going to have defensive armament as well.

In 1943 the Kriegsmarine withdrew their interest on the Me.264 in favour of the Ju.290 and the planned Ju.390, while the Luftwaffe showed interest on the design of the Focke-Wulf Ta.400 and the Heinkel He.277 as Amerikabomber candidates in May 1943, based on performance estimations, so further payments to Messerschmitt for work on the project were cut out so Erhard Milch, ordered further development of the Me.264 to stop, in order to concentrate on the jet-powered Messerschmitt Me.262 fighter.

Late in 1943, the Me.264 V2 was destroyed during a bombardment. On 18th July 1944, the first prototype, which was assigned to Transportstaffel 5 (Transport Squadron 5) as a transport airplane, was damaged during an Allied bombing raid and was not repaired. That same raid destroyed the third unfinished prototype. 

After the cancellation of the competing He.277 in April 1944, on 23rd September 1944, work on the Me.264 was officially cancelled. Messerschmitt proposed a six-engine version, the Me.264/6m (or, unofficially, the Me.364) but it didn't go beyond the project stage.

Sources:

1. https://en.wikipedia.org/wiki/Messerschmitt_Me_264

2. https://www.valka.cz/Messerschmitt-Me-264-t14202

3. Osprey Publishing - X-Planes 2 - Messerschmitt Me 264 Amerikabomber

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

Mitsubishi G4M, part three

 

As the war kept going on, bomber designs intended to replace the G4M failed to materialise and Mitsubishi created additional versions to cope with various new roles needed and to eliminate weaknesses in the design, including various engine and weapons.

The first version, the G4M1, suffered some alterations throughout its operational history. In March 1942 new machines were fitted with a supercharger in their Mitsubishi Mk4E 'Kasei' radial engines, in order to improve high altitude performance. These superchargers became standard in August that same year from 406th production aircraft onwards. That same summer, propeller spinners were introduced and in March 1943, aircraft's armour was reinforced though its maximum range and speed was slightly reduced due to the extra weight.

Shortly later, that same spring, the outer half of the tail cone was cut away to improve tail gunner's field of fire. In August, a completely redesigned tail cone was introduced with reduced framing and wide V-shaped cut out. This form of tail cone was standard for every G4M2. In September, individual exhaust stacks were introduced from 954th airframe onwards.

A total of 1.264 G4M1 were manufactured from September 1937 (when the two prototypes were completed) until January 1944 when production of the G4M1 ceased. 

The second version, named G4M2, whose prototype flew for the first time in December 1942, was powered by two Mitsubishi Mk4P 'Kasei' Model 21 engine, rated at 1.775 hp of power driving four-bladed propellers, capable of achieving full feathering function. Main wings were redesigned as well to include LB type laminar flow airfoil and tail horizontal stabilizer area was widened, which improved service ceiling and maximum speed. This version had also larger fuel tanks, which made for longer range. It also featured a new electrically powered tail turret armed with a single 20 mm Type 99 cannon plus a dorsal turret armed with another Type 99 cannon, in lieu of the G4M1's Type 92 7,92 mm machine gun. The remaining posts, nose, waists and cockpit side, were provided each with a single Type 92 machine gun. External differences from the G4M1 included also increased nose glazing, flush side gun positions instead of blisters and rounded wing tips and tail surfaces. These improvements allowed the G4M2 to carry bigger payloads either in bombs or torpedoes. It entered service in July 1943.

Another famous action involving a G4M during World War 2, was the attack that resulted in the death of Admiral Yamamoto. On 18th April 1943 sixteen Lockheed P-38 Lightnings shot down a G4M1 carrying Admiral Yamamoto. In that same battle, another G4M1 carrying Chief of Staff Vice-Admiral Matome Ugaki was also shot down, though Ugaki survived the crash.

The G4M1 was gradually replaced by the G4M2 from June/July 1943 onwards, serving this way in the campaigns of New Guinea, the Solomon Islands and the South Pacific Area, defence of Marianas and, finally in Okinawa. 

Sources:

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

2. https://www.valka.cz/Micubisi-G4M1-13-Betty-t31301

3. https://www.valka.cz/Micubisi-G4M1-12-Si-t64994

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

5. https://www.valka.cz/Micubisi-G4M1-11-Betty-t1284

6. Bunrin Do - Famous Airplanes Of The World 59 - Mitsubishi G4M Betty (translated as much as we could)

Mitsubishi G4M, part two

 

The Mitsubishi G4M, when used against fixed ground targets like supply depots, naval ports or airfields, it was a much harder target to intercept. Owing to its long range and high speed, the G4M could appear from any direction, and be gone before any fighter intercepted them. The 20 mm Type 99 cannon present at the tail was a much heavier defensive weapon for the time and made attacks from the rear quite dangerous. Sometimes, if they were not hit (and caught fire) in the wings' fuel tanks, by anti-air fire or by machine gun bullets from an enemy fighter, they proved to remain airborne despite being heavily damaged. An example of this sturdiness showed when four G4M attacked the American Heavy Cruiser USS Chicago (CA-29) on 30th January 1943, and three of the four surviving G4Ms returned to their bases flying on one engine only. 

The most famous action of the war performed by an G4M was the torpedo attack on the Battleship HMS Prince on Wales (53) and Battlecruiser HMS Repulse (34) off the Eastern shore of Malaya, shortly after Pearl Harbor, on 10th December 1941. The G4M stroke together with older G3M bombers which made high-level bombing rounds. HMS Prince of Wales and HMS Repulse were the first two capital ships to be sunk exclusively by aerial attacks during a war while in open waters. The G4Ms belonged to the Kanoya Kokutai (Kanoya Air Group), Genzan Kokutai and Mihoro Kokutai. All these groups were trained in low-level torpedo attacks (less than 10 m -30 ft- high) and in long-range over-ocean navigation, so they could hit naval targets while moving quickly at sea. 

G4Ms were employed later for attacking Allied shipping and land targets during the six-months-long Guadalcanal Campaign, in the Solomon Islands in late 1942. More than 100 G4M1s and their crew were lost, with few replacements available, during the many battles around Guadalcanal area, from August to October 1942. On 8th August 1942, during the second days of American Marine landings on the island, 23 Imperial Japanese Navys (IJN) G4M1s attacked American ships at Lunga point, but 18 of them were shot down by heavy anti-air fire or carrier-based Grumman F4F Wildcat fighters. A total of 18 Japanese crews (120 aviators) were lost at Lunga Point. 

Sources:

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

2. https://www.valka.cz/topic/view/1284

3. Bunrin Do - Famous Airplanes Of The World 59 - Mitsubishi G4M Betty (translated as much as we could)

MItsubishi G4M, part one

 

The G4M was designed as a long range and high speed bomber at the time it was introduced. In order to meet the ambitious specifications issued by the Imperial Japanese Navy (IJN) which called for a bomber capable of achieving a top speed of 398 km per hour (247.306 mph), a service ceiling of 3.000 m (9.800 ft), a range of 4.722 km (2.934 milles) unloaded and 3.700 km (2.300 milles) when loaded with 800 kg (1.800 lb) of payload, Mitsubishi's team, lead by Kiro Honjo, did not incorporate self-sealing fuel tanks and armour plating in order to save weight to achieve a longer range. This decision made both the A6M Zero and the G4M vulnerable to machine gun and anti-air fire. 

Japanese pilots nicknamed the G4M as "Hamaki" (cigar) because of its shape and Allied pilots nicknamed it as "the flying lighter", "the flying zippo" or "the one-shot lighter" because of its easiness to ignite when hit in the wing fuel tanks. 

Given some defensive deficiencies observed on the previous model, the G3M, the first production variant, the G4M1 included a single 7.7 mm (0.303 in) Type 92 machine gun in the nose. This first variant carried also a dorsal Type 92 machine plus two additional ones located in lateral beams. The tail was guarded by a single 20 mm Type 99 cannon placed inside a cupola. The whole machine was powered by two Mitsubishi Mk4A Kasei 11 radial engines which delivered 1.530 hp of power and had a payload of up to 1.000 kg (2.204 pounds) of bombs or a single 858 kg (1891.57 pounds) aerial torpedo.

In retrospective, the G4M was, in terms of performance, similar to other contemporary medium bombers such as the German Heinkel He.111, the North American B-25 Mitchell or the Vickers Wellington. Just like these bombers, the G4M was extensively in anti-shipping strikes from 1941 until 1944 when it became a rather easy prey for Allied fighters.

It was used for the first time in combat on 13th September 1940 in mainland China, in a bombing raid against the city of Hankow. Twenty-seven G4M of the 1st Rengo Kokutai departed from Taipei, Omura and Jeju escorted by 12 A6M Zero fighters. Similar bombing operations took place in May 1941. In December 1941 one hundred and seven G4Ms departed from Taipei, Formosa, crossed the Luzon strait and bombed the Philippines, opening the Japanese invasions in the South-Western Pacific Theatre. 

During the first year of combat, the G4M was a success. They bombed Clark Field, the main US Army Air Base in the Philippines on 8th December 1941 and was instrumental at the aerial raid that sank both HMS Prince of Wales (53) and HMS Repulse (34) Battleship and Battlecruiser respectively. Two days later, they took part in the bombing of Katherine, in Australia, being that the deepest inland attack on Australian territory during the whole war at over 200 milles (322 km). The G4M took advantage of the Allied weak fighter opposition during the earliest stages of the War in the Pacific, and attacked targets ranging from the Aleutian Islands to Australia, thanks to its long range. The flaw of not having self-sealing fuel tanks wasn't an inconvenience at this early point of the theatre.

Sources:

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

2. https://www.valka.cz/topic/view/1284

3. Bunrin Do - Famous Airplanes Of The World 59 - Mitsubishi G4M Betty (translated as much as we could)