Okajima G6O
Crew: 10 (pilot, co-pilot, navigator, bombardier/nose gunner, flight engineer/dorsal turret gunner, radio operator, waist gunner (2), ventral turret gunner, tail gunner.
Length: 26,98m
Wingspan: 37,33m
Empty weight: 18.750kg
Max takeoff weight: 34.075kg
Powerplant: x4 Mitsubishi Kasei24 radial engines, 1.850 hp each
Maximum speed: 482km/h at 8.800m
Combat Range: 5.800km (2.000kg payload), 5.500km (2.800kg payload), 4.900km (4.500kg payload), 3.200km (6.000kg payload), 1.300km (8.000kg payload)
Armament: 6x 13mm machine guns + 2x 7.7mm machine guns
Bombload: 6.000kg (8.000kg overload)
G6O1-J
Crew: 11 (pilot, co-pilot, navigator, nose gunner, flight engineer/dorsal turret gunner, radio operator, ventral gondola gunner (2), ventral turret gunner, aft dorsal turret gunner, tail gunner.
Length: 26,98m
Wingspan: 37,33m
Empty weight: 18.841kg
Max takeoff weight: 28.166kg
Powerplant: x4 Mitsubishi Kasei24 radial engines, 1.850 hp each
Maximum speed: 506km/h at 8.800m
Combat Range: 5.500km
Armament: 5x 20m cannons + 7x 13mm machine guns
G6O2
Crew: 10 (pilot, co-pilot, navigator, bombardier/nose gunner, flight engineer/dorsal turret gunner, radio operator, waist gunner (2), ventral turret gunner, tail gunner.
Length: 26,98m
Wingspan: 37,33m
Empty weight: 19.069kg
Max takeoff weight: 34.304kg
Powerplant: x4 turbosupercharged Nakajima Homare21 radial engines, 2.041 hp each
Maximum speed: 568km/h at 10.700m
Combat Range: 4.100km (4.500kg payload)
Armament: 2x 20mm cannons + 8x 13mm machine guns
Bombload: 6.000kg (8.000kg overload)
For two years, between late 1943 and late 1945, The Okajima G6O, better known to the allies as "Rachel", was the only Axis heavy bomber in service in the Pacific Ocean. During this timeframe, it earned a fearful reputation, second only to that of the Thiarian Caproni-Atlantach 11C, as one of the best assets the Axis could field in the war.
Koko no Kaigun expressed interest for a long-ranged heavy bomber as early as 1939, but no domestic projects were started until mid 1941, when the Japanese Nakajima G5N proved to be a failure due to lacking performance, engine unreliability and design complexity. Both Okajima and Enomoto were tasked to develop a new airplane under a 5-5-5 performance goal: delivering a 5.000kg payload over a range of 5.000km with a 500km/h top speed. Enough, on paper, to hit as far as Pearl harbor or Alaska even when taking off from Kokoan airfields. Enomoto eventually halted developement midway through mock-up phase as Okajima was already far ahead with four prototypes being assembled by fall 1942. Kokoan designers also had the chance to evaluate one of the B-17s the Japanese had captured during the invasion of the Philippines. Elements of the American bomber went into the bombsight mechanism, main landing gear and, later on in the G6O2 model, the tail turret. The first airframe was ready in December 1942 and first flew on January 16th 1943. A mid-wing monoplane with a large wingspan, the G6O1 was powered by four Mitsubishi Kasei21 radials each generating 1.850hp. In addition to all its fuel tanks being self-sealing, it had a main defensive armament of six 13mm machine guns: four in two twin turrets, one ventral and one dorsal, plus one in the nose and one in the tail. Two 7.7mm pieces were also fitted in two offset waist positions to add some extra protection from enemy fighters. Its bomb bay could easily carry up to 6.000kg of bombs, or even 8.000kg bordering overload, fitting all types of ordinance available, from 60 to 820kg bombs. Two 850kg torpedoes (1.080kg ones on the G6O2) could also fit, but the type was never used in this role. Operationally the plane had a top speed of 482km/h at an 8.800m celiling and a 4.900km range with a 4.500kg bombload. Slightly less than what was requested, but still enough for the aircraft to be considered very satisfactory and immediately ordered into production. Moreover, with the Aleutians and Midway occupied by Kokoan forces by that time, even notwithstanding the reduced range, the aicrafts could hit even further into American territories. Air raids against eastern Hawaiian targets like Pearl Harbor had been removed from the plans by that time however. US air power in the area was considered as being too extensive.
Another potential problem that emerged during developement concerned escorting the bomber on its missions. When operating on maximum range, no Kokoan fighter kould keep up all the way (the J6I2 heavy fighter had a combat radius of 1.300 km, compared to the 2.400km of the G6O1).
In a similar manner to the Japanese G4M/G6M duo, Okajima modified the basic G6O1 airframe by deleting the bomb bay and adding a ventral gondola housing two twin 20mm cannons. The tail gunner also swapped its 13mm piece for a 20mm. A second dorsal turret was also added. All for a total armament of five 20mm and seven 13mm barrels. Top speed and range were slightly higher, at 506km/h and 5.500km. The so called G6O1-J Yokutan goei sentoki (wingtip convoy fighter) first flew in July 1943 and was in service by November of the same year.
By september 1943 Koko no Kaigun had recieved enough G6O1s to form a squadron and the aircraft made its combat debut on October 12 1943. Taking off from Adak island 40 G6O1s of the 132nd and 159th Kokutai arched over the Bering Sea and bombed Anchorage, Fort Richardson and Elmendorf Field, dropping almost 150.000kg of conventional and fragmentation bombs on the target. Achieving almost a completed and unexpected surprise, with only four bombers not coming back, the first bombing of Anchorage was a resounding propaganda success for Koko and a great embarassment for the US military, whose intel had previously reported that Koko had no aircraft with enough range to even attempt such a raid.
The G6O1 had proved itself to be very sturdy and capable of absorbing a significant amount of damage while still be able to fly, and in lieu of the success just achieved Koko no Kaigun decided to go forward with further attacks. Anchorage was then hit again on October 27 and November 19. The last attack saw the Americans better prepared, resulting in 13 bombers lost despite their Yokutan escorts were now part of the formation. Koko no Kaigun thus chose to step back from its high-end propaganda targets and focus on other more feasible military objectives: Kodiak and Fort Mears were hit on November 30 and December 11. Losses immediately plummeted to more acceptable figures.
During the rest of the bloody Aleutian Campaign, more properly escorted G6Os repeatedly and relentlessly hit Fort Morrow, Cape field, Fort Glenn, Cold Bay, Fort Meyers and Dutch Harbor. Hampering US military advancements from December 1943 to May 1945. In the rest of the Pacific, the bombers were used to hit enemy positions in the Solomons, Port Moresby, Darwin and other northern Australian strategic targets (an average of 5 times each month between March and November 1944). Recerche was not spared either, with Hopetoun hit three times on April 21st, June 4th and June 26th 1944.
The exploits the aircraft managed to achieve in its first sorties immediately attracted the interest of Koko' Army as well, promptly requesting to get some deliveries of the type in order to boost their war efforts. The first aircrafts started to join their ranks by the end of 1943. Eventually, about a fifth of the total G6O production saw service with Koko no Rikugun. Those units were extensively used in China and the Southeast Asian theater, especially during the Burma Campaign.
Due to the rapidly increasing numbers of more modern American fighters in the theatre and steadily increasing attriton rates, Okajima started developement of an improved G6O2 model during the second half of 1944. The tail turret was completely redesigned with the single 13mm piece replaced by a twin 20mm cannon. The nose turret switched from a single to a twin 13mm machine gun and the waist positions got upgunned from 7.7 to 13mm. Both dorsal and ventral turrets were replaced with improved ones capable of faster traverse end elevation rates. All for a total of two 20mm cannons and eight 13mm machine guns of defensive armament. An extra set of radar recievers was also added near the tail to better detect incoming enemy planes, and a few more armor plates were added to improve crew protection.
Engine-wise, the Kasei radials were replaced by turbosupercharged Nakajima Homare24 of 2.041hp, capable of pushing the plane at a much faster speed of 568km/h at a ceiling of 10.700m. which made them much more impervious to interception by enemy fighters. Range with a 4.500kg payload decreased to 4.100km, but the loss in combat radius was not considered detrimental as US forces were now much closer to Koko's mainland. The G6O2 made its first flight in March 1945 and became operational in August. Too late and in too little numbers to truly make an impact on the war. Out of a total production of 1.144 units, 976 were of the G6O1 model, plus 85 G6O1-J and 83 G6O2.
When Koko uprisings started, in November 1945, there were still around 400 G6Os of all types still operational around the Pacific. Of them, 156 survived to the end of the war, most of the others being destroyed on the ground during bombings or through acts of sabotage. After inspection by US engineers, 25 were considered being still airworthy without the need of repairs of mainenance work. Six of those airframes were taken for post-war evaluation and testing by the United States and UK (the Soviets were denied access by weirdly granting a request from Koko's provisonal government). Most of the test examples and damaged aircrafts left in Kokoan hands were later stored, disassembled or scrapped, both for materials and by surrendering terms conditions. A couple eventually survived: One of the four aircrafts flown in the united States is reported still laying disassembled at the Smithsonian Institution storage facility in Suitland, Maryland. Koko managed to salvage one of its damaged surviving G6O2s, later restoring it to its proper wartime appearance. Although not airworty, the plane has been on display at the Hoshiguma Air Museum since the early 70s.
edit 1, May 6th: changed G6O2 colour from brown to black.
edit 2, May 10th: fiexd typos on the text.
