Tachikawa Ki-74

by Mitch on June 3, 2012 0 Comments

Although first conceived as early as 1939, the Tachikawa Ki-74 had not been placed in full production when the Pacific war ended. During those six years its intended role had been changed from that of long-range reconnaissance to that of long-range stratospheric bombing.

Under the guidance of Dr Kimura, the Ki-74 was originally designed in the spring of 1939 to meet the requirements of a specification issued by the Koku Hombu and calling for a long-range reconnaissance aircraft capable of operating west of Lake Baikal from Manchurian bases. The aircraft was to have a range of 5,000 km (3,107 miles) at a cruising speed of at least 450 km/h (280 mph). To meet these performance requirements, Dr Kimura proposed using a pair of 2,400 hp Mitsubishi Ha-214M radials driving six-blade propellers. and fitting a pressure cabin. However, pending development of the pressure cabin system tested on the Tachikawa SS-1 and A-26/Ki-77, the project was temporarily suspended.

Late in 1941 the project was revived as a long-range high-altitude bomber-reconnaissance aircraft capable of bombing the United States mainland. To fit the aircraft for its new role, Tachikawa added bombing equipment, self-sealing fuel tanks and armour to the original design and decided to replace the Ha-214M engines with a pair of Mitsubishi Ha-211-I radials, rated at 2,200 hp for take-off, 2,070 hp at 1,000 m (3,280 ft) and 1,720 hp at 9,500 m (31,170 ft). The design of the aircraft was approved by the Koku Hombu in September 1942 and construction of three prototypes was authorised. The first prototype, completed in March 1944, was followed by two externally identical aircraft which were powered by a pair of turbosupercharged Ha-211-I Ru radials, rated at 2,200 hp for take-off, 2,070 hp at 1,000 m (3,280 ft) and 1,720 hp at 9,500 m (31,170 ft). However, during the flight trial programme both versions of the Mitsubishi Ha-211 suffered from teething troubles and it was decided to replace them on the pre-production aircraft with the lower-powered but more reliable turbosupercharged Mitsubishi Ha-104 Ru radials, rated at 2,000 hp for take-off, 1,900 hp at 2,000 m (6,560 ft) and 1,750 hp at 6,000 m (19,685 ft).

Thirteen Ha-104 Ru powered pre-production aircraft were built and were still undergoing tests when the war ended. All five crew members were seated in a pressure cabin in the forward fuselage, and the aircraft was armed with a single remotely-controlled 12.7 mm (0.5 in) machine-gun in the tail and carried a bomb-load of 1,000 kg (2,205 lb). Plans were made to use the Ki-74s in bombing attacks against B-29 bases at Saipan as soon as sufficient aircraft were available, but the Japanese surrender terminated the project. Although the Ki-74 was never encountered during the war, the Allies were aware of its development, but thinking at first that it was a 'super-range, high-speed fighter' intended for long-range escort duty they accordingly assigned to it a male name: 'Pat'; when the true role of the aircraft was discovered the code-name was changed to 'Patsy'.

The fourth pre-production aircraft (Ki-74 c/n 7) was modified in 1944 to undertake non-stop flights between Japan and Germany, but the Third Reich capitulated before the first of these flights could be made. Other developments included a pure bomber version, the Ki-74-II with the bomb-load increased to 2,000 kg (4,410 lb), and a transport version, but both these projects were abandoned before completion.

Technical Data

Manufacturer: Tachikawa Hikoki KK (Tachikawa Aeroplane Co Ltd).
Type: Twin-engined high-altitude long-range reconnaissance-bomber.
Crew (5): Enclosed in pressure cabin.
Powerplant: (1st prototype) Two Mitsubishi Ha-211-I eighteen-cylinder air-cooled radial engine, driving four-blade metal propellers, (2nd and 3rd prototypes) two Mitsubishi Ha-221-I Ru eighteen-cylinder air-cooled radial engines, driving four-blade metal propellers, (4th-16th aircraft) two Mitsubishi Ha-104 eighteen-cylinder air-cooled radial engines, driving four-blade metal propellers.
Armament: One remotely-controlled 12.7 mm (0.5 in) Type 1 (Ho-103) machine-gun. Bomb-load: 1,000 kg (2,205 lb).
Dimensions: Span 27 m (88 ft 7 in); length 17.65 m (57 ft 10 7/8 in); height 5.1 m (16 ft 8 25/32 in); wing area 80 sq m (861.11 sq ft).
weights: Empty 10,200 kg (22,487 lb); loaded 19,400 kg (42,770 lb); wing loading 242.5 kg/sq m ( 49.7 lb/sq ft); power loading 4.4 kg/hp (9.7 lb/hp).
Performance: maximum speed 570 km/h (354 mph) at 8,500 m (27,890 ft) cruising speed 400 km/h (249 mph) at 8,000 m (26,245 ft); climb to 8,000 m (26,245 ft) in 17 min; service ceiling 12,000 m (39,370 ft); range 8,000 km (4,971 miles).
Production: A total of 16 Ki-74s were built by Tachikawa Hikoki KK between march 1944 and August 1945.

Mitsubishi G4M Part I

by Mitch on January 29, 2012 1 Comment

The bulbous G4M was the most numerous and best-known Japanese medium bomber of World War II. It possessed incredible range, but its unarmored fuel tanks led to the unenviable nickname “Flying Lighter.”


In 1937 the Imperial Japanese Navy issued an incredibly difficult specification mandating production of land-based bombers with even greater range than the superb G3M. Although such performance was usually attained by four-engine designs, the new craft was restricted to only two. That year Kiro Honjo commenced work on a machine whereby fuel capacity was emphasized to the exclusion of all other considerations. In 1939 the G4M prototype was flown as an all-metal, midwing design with rakish wings and tail surfaces melded to a rotund fuselage. As expected, the airplane performed well and possessed impressive range. However, this was achieved by stuffing as much fuel as possible into wing tanks that remained unarmored to save weight; crew armor was also deleted for the same reason. Nonetheless, the navy was highly pleased with the G4M, and in 1940 it entered production. The following year they were baptized under fire in northern China, performing well against limited opposition. When the Pacific war broke out in December 1941, roughly 160 G4Ms were in service. Allied forces gave them the code name Betty.


The G4M came as quite a surprise to British and American forces, who believed themselves beyond the reach of medium bombers. But in quick succession, G4Ms helped sink the battleships HMS Repulse and Prince of Wales, and they plastered airfields throughout the Philippines. It was not until the spring of 1942 that the Betty’s weakness was revealed. The very attributes endowing it with such long range caused it be destroyed by a few tracer rounds. The G4Ms took staggering losses during the Guadalcanal campaign, and the Japanese finally introduced self-sealing tanks and crew armor in subsequent versions. One of the last roles of the G4M would be to carry the Yokosuka MXY 7 Oka suicide rocket. Production totaled 2,416 of all versions.


G4M1 Model 11: 1172 examples (including prototypes.)

G4M2 Models 22, 22 Ko and 22 Otsu: 429 examples.

G4M2a, Models 24, 24 Ko, 24 Otsu, 24 Hei, and 24 Tei: 713 examples.

G4M3 Models 34 Ko, 34 Otsu, and 34 Hei: 91 examples.

G6M1: 30 examples.

Total production of all versions: 2,435 examples.

Specifications (G4M1, Model 11)

General characteristics

    Crew: 7 (main-pilot, co-pilot, navigator/bombardier/nose gunner, captain/top turret gunner, radio operator/waist gunner, engine mechanic/waist gunner, tail gunner)

    Length: 19.97 m (65 ft 6¼ in)

    Wingspan: 24.89 m (81 ft 7¾ in)

    Height: 4.9 m (16 ft 1 in (in a horizontal position))

    Wing area: 78.13 m² (840.9 ft²)

    Airfoil: Mitsubishi type

    Empty weight: 6,741 kg (14,860 lb)

    Loaded weight: 9,500 kg (20,944 lb)

    Max. takeoff weight: 12,860 kg (28,350 lb)

    Powerplant: 2 × Mitsubishi MK4A-11 "Kasei" (Fire star) 14 cylinder radial engines, 1,141 kW (1,530 hp) each

    Propellers: 4-bladed Hamilton Standard licensed Sumitomo constant speed variable-pitch


    Maximum speed: 428 km/h (230 kn, 265 mph)

    Cruise speed: 315 km/h (175 kn, 196 mph)

    Stall speed: 120 km (75 mph)

    Range: 2,852 km, one way (1,540 nmi, 1,771 mi, one way (overloaded: 5,040 km (2721 nmi, 3,132 mi)))

    Service ceiling: 8,500 m (27,890 ft)

    Rate of climb: 550 m/min (1,800 ft/min)


    Guns: 1× 20 mm Type 99 cannon (tail turret), 4× 7.7 mm Type 92 machine gun (nose turret ×1, waist positions ×2, top turret ×1)

    Bombs: 1× 858 kg (1,892 lb) Type 91 Kai-3 (improved model 3) aerial torpedo or 1× 800 kg (1,764 lb) bomb or 4× 250 kg (551 lb) bombs

Mitsubishi G4M Part II

by Mitch on January 29, 2012 0 Comments

Few would know it by its official designation, the Navy Type 1 Attack Bomber. The Allies called it the BETTY but to the men that flew the airplane, it was popularly, but unofficially, the 'Hamaki,' Japanese for cigar, in honour of the airplane's rotund, cigar-shaped fuselage. The Japanese built more of them than any other bomber during World War II. From the first day of war until after the surrender, BETTY bombers saw service throughout the Pacific and Indian Oceans. Like its stable mate, Mitsubishi's Zero Fighter the Hamaki soldiered on long after it became obsolete, even dangerous, to fly wherever Allied interceptors prowled.


In July 1937, the new Mitsubishi G3M bomber (Allied codename NELL) went into service in China. Only two months later, the Navy issued a specification to Mitsubishi for a NELL replacement. At that time, the requirements were unprecedented for a twin-engine, land-based attack bomber: flying at a top speed of 398 kph (247 mph) and an altitude of 3,000 m (9,845 ft), the new bomber had to fly a distance of 4,722 km (2,933 miles) without a torpedo or equivalent weight in bombs. When carrying an 800 kg (1,768 lb) torpedo or the same weight in bombs, the Navy needed the bomber to fly at least 3,700 km (2,300 mi).


To meet the requirements, a Mitsubishi design team led by Kiro Honjo crafted an airplane called the G4M with fuel tanks in the wings that were not resistant to explosion when punctured during combat. These tanks were much lighter in weight than explosion-proof (also called 'self-sealing') gas tanks. The decision not to incorporate the heavier, safer fuel tanks was necessary to meet the Navy's range requirements. Mitsubishi incorporated this same design feature in the Zero, for the same reasons and with the same results. Both aircraft had unprecedented range but they were also extremely vulnerable to the machine gun and cannon fire from Allied fighter aircraft. The BETTY was so prone to ignite that the Allies nicknamed it the 'flying lighter.'


The fuselage was streamlined but rotund to allow space for a bomb bay within the wing centre section and to allow the 7 to 9-man crew to move about. About half the crew were gunners who manned the defensive armament positions. Bomber crews flying the NELL were virtually incapable of defending themselves from concentrated fighter attacks, so Honjo paid special attention to this aspect of the G4M. He incorporated 7.7 mm (.30 cal.) guns in the nose, atop the mid-fuselage behind the cockpit, and on both sides of the fuselage behind the wing. In the tail, he introduced a 20 mm cannon. Although the G4M now had a more potent sting, Honjo again sacrificed crew protection to the Navy's demands for great range. He omitted armour plate.


The first G4M prototype left the factory in September 1939 and made the trek to Kagamigahara Airfield for Mitsubishi's Nagoya plant had no company airstrip. Kagamigahara was 48 km (30 miles) to the north. Japan's newest and most advanced bomber made the trip, disassembled and stacked on five ox-drawn farm carts, over unpaved roads! After arriving at the airfield, the first G4M was reassembled and flown by test pilot Katsuzo Shima on October 23, 1939. Initial results were impressive, but the Navy shelved the bomber for a time in favour of a variant to be called the G6M1. Navy leaders hoped that by increasing the number of defensive cannons, the G6M1 could become a heavy escort fighter for other bombers but this diversion failed to live up to expectations, and the Navy ordered the G4M1 into production. The U. S. Army Air Corps conducted a similar experiment using a modified Boeing B-17 bomber designated the B-40 but this idea too failed to survive operational testing and was soon abandoned. The first production G4M rolled off the line in April 1941. For the remainder of the war, the BETTY assembly line continued to run.


Operationally, BETTY crews achieved much in their first year of combat. They devastated Clark Field, Philippine Islands, on December 8, 1941, and participated in sinking the British battleships HMS "Prince of Wales" and HMS "Repulse" on December 10. They ranged across the length and breadth of the Pacific theatre, attacking targets from the Aleutians to Australia. Against limited fighter opposition, the lack of armour and self-sealing fuel tanks was no hindrance. The savings in airframe weight allowed the G4M to attack targets at unprecedented ranges. But as Allied fighter strength increased, the BETTY began to reveal its fatal vulnerabilities. Admiral Isoroku Yamamoto, architect of the Pearl Harbour attack, died on April 18, 1943, along with his entire staff when U. S. Army Air Corps P-38 Lightnings intercepted and destroyed the two BETTY bombers that carried them. Six escorting Zeros flew guard but in a matter of seconds, the Air Corps pilots shrugged off the escorting fighters and sent both BETTYs crashing down in flames.


As the war dragged, improved bombers failed to materialize so Mitsubishi fielded different versions of the G4M to fulfil new missions, and to eliminate the various weaknesses in the basic design. Front-line combat units operated many variants and sub-variants with different engines and armament packages. The G4M2 was a complete redesign but it did not overcome the airplane's vulnerability to Allied firepower. Mitsubishi tried again to reduce the bomber's tendency to burn. The firm changed the wing to a single-spar configuration and installed self-sealing fuel tanks with a capacity about one-third less than earlier versions. The capacity dropped because of the material inserted in the tank to block leaking fuel when gunfire perforated the tank. Armour plate was also added to all crew positions and the tail turret was redesigned. As a result of these modifications, the fuselage was shortened and the centre-of-gravity shifted forward. To re-balance the bomber, dihedral was added to the horizontal stabilizer. This version was called the G4M Model 34.



An early-production Mitsubishi G4M1 Model 11 without the propeller spinners


G4M1 Prototypes

    Japanese Navy land Based Bomber Type 1. Two prototypes built.

G4M1 Model 11

    Japanese Navy Land Attack Bomber Type 1. The first bomber model of series, with 1,140 kW (1,530 hp) Mitsubishi MK4A Kasei Model 11 engines driving three-blade propellers. Following modifications were made during the production:

    March 1942: The first aircraft (241st production example) fitted with MK4E Kasei Model 15 engines with larger superchargers for better high altitude performance, became standard in August 1942 from 406th aircraft onwards. These MK4E-engined aircraft have often (erroneously) been referred as the G4M1 Model 12.

    Summer 1942: Propeller spinners introduced.

    March 1943: From 663rd machine onwards, 30 mm (1.18 in) rubber ply sheets installed beneath the wing outer surfaces to protect the undersides of the fuel tanks (speed reduced by 9 km/h/6 mph and range by 315 km/196 mi), 5 mm (.2 in) armour plates added into tail gunner's compartment.

    Spring 1943: Outer half of the tail cone cut away in order to improve tail gunner's field of fire.

    August 1943: A completely redesigned tail cone, with reduced framing and wide V-shaped cut out; this form of tail cone was also used in all G4M2 models.

    September 1943: Individual exhaust stacks from 954th airframe onwards.

Production of the G4M1 ended in January 1944.


The first of the four G4M2 prototypes flew in December 1942. It differed from the preceding model in having MK4P Kasei Model 21 engines with VDM Electric four-blade propellers capable of full feathering function, redesigned main wings with LB type laminar flow airfoil,  and widened tail horizontal stabilizer wing area, which improved service ceiling to 8,950 m (29,360 ft) and maximum speed to 437 km/h (236 kn, 272 mph). Main wing fuel tanks were enlarged to 6,490 L (1,715 US gal) which increased the range to 6,100 km (3,790 mi/ 3,294 nmi overloaded, one way). An electrically powered dorsal turret featuring a 20 mm cannon was introduced in place of G4M1's dorsal position with a 7.7 mm machine gun, total guns armed were 2 × 20 mm Type 99 cannon (1 × tail turret, 1 × top turret), 4 × 7.7 mm Type 92 machine gun (1 × nose, 2 × waist, 1 × cockpit side). External differences also included increased nose glazing, flush side gun positions instead of blisters, and rounded tips of wings and tail surfaces. These major improvements also made it possible for the G4M2 to carry more powerful bombs; 1 × 1,055 kg (2,326 lb) Type 91 Kai-7 (improved model 7) aerial torpedo or 1 × 800 kg (1,760 lb) bomb or 2 × 500 kg (1,100 lb) bombs or one Type 3 – 800 kg (1,760 lb) no.31 ray-detective type bomb + 12 × 60 kg (130 lb) bombs. This model, G4M2, was put into service in mid-1943.

G4M2 Model 22

    The base model, the first production example completed in July 1943. Introduced bulged bomb bay doors from 65th aircraft onwards, and an optically flat panel in the nose cone from the 105th aircraft onwards.

G4M2 Model 22Ko

    Very similar to previous model. Carried Type 3 Ku Mark 6 search radar and was armed with two 20 mm Type 99 Mark 1 cannons replacing the 7.7 mm machine guns in the lateral positions.

G4M2 Model 22 Otsu

    Dorsal turret cannon changed to longer-barreled 20 mm Type 99 Mark 2.

G4M2a Model 24

    Modified Model 22, MK4T Kasei 25 1,340 kW (1,800 hp) engines, with bulged bomb bay doors as standard for larger bomb capacity. Externally distinguishable from the Model 22 by a carburetor air intake on the top of the engine cowling.

G4M2a Model 24 Ko/Otsu

    Armament similar to Model 22 Ko/Otsu respectively.

G4M2a Model 24 Hei

    Modified 24 Otsu, with one 13.2 mm (.51 in) Type 2 machine gun mounted in tip of the nose cone, radar antenna relocated from that position to above the nose cone.

G4M2b Model 25

    One G4M2a modified to MK4T-B Kasei 25 Otsu 1,360 kW (1,825 hp) engines. Only experimental.

G4M2c Model 26

    Two G4M2a modified to MK4T-B Ru Kasei 25b 1,360 kW (1,825 hp) engines with turbochargers.

G4M2d Model 27

    One G4M2 modified to MK4V Kasei 27 1,340 kW (1,800 hp) engines.

G4M2e Model 24 Tei

    Special version for the transport of the ramming attack bomb plane Kugisho/Yokosuka MXY-7 Ohka ("Baka") Model 11, conversions of G4M2a Models 24 Otsu and 24 Hei. Had armour protection for the pilots and fuselage fuel tanks.

MXY11 Yokosuka Navy Type 1 Attack Bomber

    Ground Decoy Non-flying replica of Mitsubishi G4M2 developed by Yokosuka


G4M3 Model 34

    Redesigned G4M2 with added self-sealing fuel tanks, improved armor protection and an entirely new tail gunner's compartment similar to that of late model B-26 Marauders. Wings were also redesigned and the horizontal tailplane was given dihedral. Armed with 2 × 7.7 mm Type 92 machine guns in nose cabin and in both side positions, and 1 × 20 mm Type 99 Model 1 cannon in dorsal turret and tail. Entered production in October 1944 in G4M3a Model 34 Ko form with 20 mm cannon in side positions instead of machine guns.

G4M3a Model 34 Otsu and Hei

    Similar modifications as in corresponding Model 24 variants.

G4M3 Model 36

    Prototype. Two G4M2 Model 34 modified to Mitsubishi MK4-T Kasei 25b Ru 1,360 kW (1,825 hp) engines.


G6M1 Japanese Navy Long Range Heavy Fighter Type 1

    Initial model of the series, armed with 20 mm Type 99 cannons between each side of fuselage and in tail, 1 × 7.7 mm machine gun in nose cabin and 1 × 30 mm cannon in front ventral position; 30 built.

G6M1-K Trainer, Japanese Navy Type 1

    Converted G6M1s.

G6M1-L2 Transport Type 1, Japanese Navy

    Modified as transports.

Hiro G2H

by Mitch on January 1, 2012 0 Comments

As the Washington (Disarmament) Treaty of 1922 limited the tonnage for capital ships for the US Navy, the Royal Navy and the Japanese Navy, so did the London (Disarmament) Treaty of 1930 limit the number of smaller ships including aircraft carriers and cruisers. Japanese Navy planners recognized the capability of Navy land-based bombers that could be used to supplement and reinforce fleet activities and thus were responsible for the development of the Hiro Navy Type 95 Land-based Attack Aircraft.


To meet this new requirement for air power starting in 1932, Rear Admiral Isoroku Yamamoto, Chief of Engineering Department, Naval Air Headquarters, called for a land-based long-range attack bomber that could fly more than 2,000nm and carry two tons of bombs. The Hiro Arsenal was selected for the project, for at that time it was the most experienced in the design of all-metal large aircraft. Chief designer was Lieut-Cdr (Ordnance) Jun Okamura who had served in this capacity for the preceding Type 91 Flying-boat project. This land-based bomber became the primary concern at the Hiro Arsenal, diverting attention from the development of the flying-boats previously described.


At the start of the project, the prototype's designation was the Hirosho 7-Shi Special Attack Aircraft, with the short designation G2HI. Structurally, it was a combination of a large wing of traditional Wagner diagonal tension-field structure and a slender fuselage of monocoque construction. The twin fins and rudders were similar to those of the final design of the Type 90-1 Flying-boats, and the ailerons were of the Junkers double-wing variety. One of the innovative features of the armament installation was a cylindrical belly gun turret which retracted into the fuselage. This feature was carried over into early versions of the Mitsubishi Navy Type 96 Land-based Attack Aircraft, that were code-named Nell by the Allies during the Pacific War.


To power the new bomber, two 900-1,180hp Type 94 water-cooled engines were selected, the most powerful aircraft engines available at that time. They were being developed by the Hiro Arsenal as a scaled-up version of the 600hp Type 90 Engine. It was felt that with these new engines, the aeroplane would be equivalent to a three- or four-engined aircraft of the time. Although the airframe dimension, wing area, and empty weight were almost identical to the Type 90-1 Flying-boat, aircraft range and payload were increased by nearly 50 percent. This was the largest land-based aeroplane in the Navy at that time, second only to the Army's Type 92 Heavy Bomber (Ki.20) of the Junkers-G 38 design, yet it was the first of such a large size to be designed from the beginning as a land-based attack bomber. With two engines, its wing span was 103 ft 11 1/4in, marginally bigger than the four-engined Boeing B-17 Flying Fortress with 103ft 9in wingspan.


The first prototype was completed on 29 April, 1933, at the Hiro Arsenal and moved by ship to Yokosuka. There it made its first flight in mid-May 1933 in the presence of Rear Admiral Yamamoto who had originated this bomber concept for the Navy. Making the first flight were Lieut-Cdr Shinnosuke Muneyuki and Lieut-Cdr Toshihiko Odahara, both of the Flight Experiment Group of the Yokosuka Kokutai. After taking off, Muneyuki made one pass over the field for the spectators and proceeded to Kasumigaura Air Base where testing was to take place.


As flight evaluations continued, it was found that the aeroplane possessed outstanding performance as the Navy's largest land-based aeroplane at that time. But shortcomings became evident, including tail vibrations caused by the light structure of the fuselage, aileron flutter, and unreliable engines. One aircraft was lost during test flying because of aileron and tail flutter, causing it to ditch in Tokyo Bay. Corrections were made to the design enough to justify production.


In June 1936, the aeroplane was officially accepted by the Navy as the Type 95 Land-based Attack Aircraft, at the same time as the Navy accepted the Type 96 Land-based Attack Aircraft (G3M 1), Nell. To avoid identity confusion between the two, the G3Ml was referred to as the Type 96 Chu-ko (Medium Attack) or simply 'Chuko,' while the G2H was called the Type 95 Dai-ko (Large Attack) or 'Dai-ko.'


After six of the G2H bombers had been produced at Hiro Arsenal, production was transferred to Mitsubishi. Before long, however, the Navy asked that production be concentrated on the smaller G3M, curtailing the G2H because of maintenance difficulties with the Type 94 Engines and the aeroplane's low-speed flying characteristics. Consequently, production ended with only two having been manufactured by Mitsubishi.


With the activation of the Kisarazu Kokutai on 1 April, 1936, all remaining G2H1s (a total of eight were built) were assigned to this unit but were regarded as second-line aircraft because of the better performance of the G3Ms.


Heavy losses were experienced by G3Ms over Nanjing in August 1937, resulting in the deployment of the G2Hs to an airfield on Saishuto Island (now Cheju Do, off the southern coast of South Korea), and while en route, and for unexplained reasons, one G2H dropped out of formation and crashed near the coast of Sagami Bay southwest of Tokyo. Once in place, and established as the 1st Combined Kokutai with other forces from Kanoya, they made their first mission into China in support of ground forces in the Shanghai area on 30 September, 1937, under the command of Lt Motokazu Mihara. They made further attacks against nine major combat areas and received considerable damage from AA fire but no aeroplanes were lost.


Disaster did catch up with these G2Hs on 24 October, 1937, when one aircraft caught fire while its engines were being started and soon exploded. The fire spread to the other G2Hs, each loaded with three 250kg, five 60kg and five 50kg bombs, exploding successively until four aircraft were destroyed and the fifth badly damaged.


Specifications (G2H1)

Twin-engined land-based mid-wing monoplane bomber. All-metal stressed skin construction.

Crew of seven.

Two 900-1, 180hp Hiro Type 94-1 eighteen-cylinder W-type water-cooled engines, driving four-bladed wooden propellers.

One nose-mounted flexible 7.7mm machine-gun, twin dorsal 7. 7mm machine-guns retractable turret-mounted, one retractable turret-mounted ventral 7.7mm machine-gun. Bomb load: six 250kg (551Ib) bombs or four 400kg (881Ib) bombs.

Span 31.68m (103ft 11 1/4in); length 20.15m (66ft 1 1/4in); height6.28m (20ft 7 1/4in); wing area 140sq m (1,506.996sq ft).

Empty weight 7,567kg (16,682Ib); loaded weight 11,000kg (24,250Ib); wing loading 78.5kg/sq m(16Ib/sq fr); powerloading 6.11 kg/hp (13.4lb/ hp).

Maximum speed 132kt (152mph) at 1,000m (3,280ft); cruising speed 90kt (104mph); climb to 3,000m (9 ,843ft) in 9min 30sec; service ceiling 5,130m (16,830ft); range 1,080 to 1,557nm (1,245 to 1,800sm).

Hirosho built six from 1933 and Mitsubishi built two from 1936.

Nakajima G5N Redux

by Mitch on November 9, 2011 3 Comments

The IJAAF version of the G5N1 was to be the Nakajima Ki-68, and the IJAAF version of the G5N2 was to be the Kawasaki Ki-85.


The Nakajima G5N Shinzan originated due to the Imperial Japanese Navy's interest in developing a long-range attack bomber capable of carrying heavy loads of bombs or torpedoes a minimum distance of 3,000 nmi (5,600 km; 3,500 mi). To meet this requirement, it became apparent a four-engine lay-out would be necessary. As Japanese aircraft manufacturers lacked experience in building such large complex aircraft, the Navy was forced to search for a suitable existing foreign-made model upon which to base the new design. It settled on the American Douglas DC-4E airliner. In 1939 the sole prototype of this airliner (previously rejected by American airline companies) was purchased by Nippon Koku K.K. (Japan Airlines Co) and clandestinely handed over to the Nakajima Aircraft Company for dismantling and inspection.


The design that emerged from this study was for an all-metal mid-wing monoplane with fabric-covered control surfaces and powered by four 1,870 hp Nakajima NK7A Mamoru 11 air-cooled radial engines driving four-bladed propellers. Notable features included a long ventral bomb-bay, glazed nose and twin tailfins replacing the DC-4E's distinctive triple rudder. The DC-4E's retractable tricycle undercarriage was retained, as well as the original wing form and powerplant arrangement. Defensive armament comprised one 20mm Type 99 Model 1 cannon each in a power-operated dorsal and tail turret plus single-mount hand-operated 7.7mm Type 97 machine guns in the nose, ventral and beam positions.


The first prototype G5N1 made its maiden flight on 10 April 1941. Overall performance proved disappointingly poor however, due to a combination of excessive weight, the unreliablity of the Mamoru engines and the complexity of the design. Only three more prototypes were completed. In an attempt to salvage the project, two additional airframes were fitted with 1,530 hp Mitsubishi MK4B 12 "Kasei" engines and redesignated G5N2s. Although the Mitsubishi engines were more reliable than the original Mamoru 11s, the aircraft was now even more hopelessly underpowered and further development of the type was halted.

Operational history

Of the six completed Shinzans, four of them (two G5N2s and two G5N1s re-engined with the Kasei 12) were relegated for use as long-range Navy transports under the designation Shinzan-Kai Model 12 Transport G5N2-L. The Allies allocated the code-name "Liz" to the aircraft, in the expectation it would be used as a bomber.


    G5N1: Four-engined heavy bomber. Production version, four built.

    G5N2: Four Mitsubishi MK4B 12 "Kasei" radial engines in place of Nakajima Mamoru 11 engines. Two built.

    G5N2-L: Long-range Navy transport conversion.

Proposed Variants

    Nakajima Ki-68: Japanese Army heavy bomber. Four Mitsubishi Ha-101 or Nakajima Ha-103 engines.

    Kawanishi Ki-85: Japanese Army heavy bomber. Four Mitsubishi Ha-111M engines.

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