Here's everything you want to know about Japanese heavy bombers but were afraid to ask
HEAVY BOMBERS
KAWASAKI
By 1943 it was realized that the bombers active service were not adequate by the way the war was going. Like the Germans, the Japanese relied on twin-engine bombers early on but they'd now reached their maximum of technology and performance. A scant few bombers were able to cope with the speeds of American fighters and take damage. A true long-range heavy bomber was needed that could fly fast.
The Navy was committed to the G8N Renzan (Mountain Range), code named "Rita," but was hampered by air raids. The Army liked the Kawasaki design for their bomber. Therein lie part of the problem. Here was country under assault day and night by air and they stubbornly chose to stay divided as rival service factions each demanded their own planes. Had they combined and concentrated their efforts it would have been realized that only one big bomber was needed.
The Ki 91 was to have a crew of eight or nine would have been housed in a pressurized fuselage 108.25 feet long. Four Mitsubishi Ha-214ru engines of 2,500HP each would have driven the plane to a maximum speed of 360 MPH. A wingspan of 157.5 feet was larger than the B-29's as was weight calculated at 127,868 lbs. loaded. 8,818 lbs. of bombs could be delivered on a 2,796-mile mission and a maximum range of 6,214 was estimated with lighter ordnance loads.
The Ki 91 was to have five power turrets- one in the nose, one on the top of the fuselage, and two beneath the fuselage along with the tail position. All would be equipped with pairs of 20 mm cannon except the tail position which would have four 20 mms!
By early 1945 the prototype was progressing in assembly but a February air raid destroyed all the tooling and jigs for the production facility rendering the project futile that late in the war.
KAWANISHI
Another contender for a high-speed long-range bomber that was fulfilled by the G8M1 "Rita" was a Kawanishi proposal- the K-100 (Type17). This thing was small like the Mitsubishi Type 17 with a crew of four in a short 50-foot fuselage. Four Nakajima Mamoru-Kai 18-cylinder radials each with 2,300 HP mounted on the 75-foot wings. Weighing just 30,000 lbs. loaded this thing could scream with a 376 MPH top speed and cruised at 230 MPH for 3,450 miles range. A ceiling of 30,732 feet was projected.
Armament was just three 20 mm cannon a 1,760-lb. torpedo or bob of the same weight.
This one never proceeded beyond preliminary designs but the concept was solid enough.
MITSUBISHI
Beyond the excellent G8M1 "Rita" 4-engine bomber tested in the post-war US, the G7M1 Taizan Type 16 project was drawn up for a high speed bomber able to carry a lighter payload shorter distances. A crew of five rode in a comfortable 65.6-foot fuselage. Four Mitsubishi Ha.42 Model 31 18-cylinder radials of 2,400 HP each turned on the 82-foot wings. All up the compact bomber weighed 35,200 lbs.
Like the Rita this ship would be quite fast at 345 MPH but with a shorter range of 1,726 miles.
Defensive armament proposed was that of two 20 mm cannon and six 13 mm machine guns. Bomb load variables could be a 1,760-lb. bomb or torpedo, two 1,100-lb. bombs or six 550-lb bombs.
This project was cancelled due to shortages and long lead time to completion.
NAKAJIMA
Before ending this chapter there is one area left to touch upon- heavy bombers. Like Germany, Japan didn't possess an early vision for their use. They certainly had the technology. Two good 4-engine bombers existed and could have been built but weren't. One design never went to prototype stage but was awesome in scope, nevertheless.
G5N2
Shinzan or Mountain Recess was code named "Liz" and had four 1,530 HP Mitsubishi Kasei 12 14-cylinder radials on its 138.25-foot wing. Seven to ten crewmen operated in its 101.75-foot fuselage. Maximum loaded weight was 70,768 lbs. with its 8,818-pound bomb load, which could be hauled to a ceiling of 23,440 feet. Maximum range was 2,647 miles. She could do 261 MPH at 13,450 feet. Defensively it mounted one 20 mm Type 99 Model 1 cannon in a dorsal turret; one 20 mm Type 99 Model 1 in the tail turret and one 7.7 mm Type 97 machine-gun in nose, ventral and waist positions.
Thought to have been inspired by a DC-4 purchased before the war, the first bomber flew in 1941. While it didn't possess long range the Japanese did use the prototypes for transport duties during the war. Four G5N1s were built along with two G5N2s.
G8N1
The Renzan or Mountain Range, code named "Rita," housed a crew of ten in her 75.25-foot fuselage while four 2,000 HP NK9K-L Homare 24 18-cylinder radials turned on the 106.75-foot wings. Normal and maximum weights were 59,084 lbs. and 70,879 lbs. 4,409 lbs. of bombs could be delivered but range was a whopping 4,639 miles. She would have been hard to intercept with a top speed of 368 MPH at 26,245 feet and a ceiling of 33,465 feet.
Armament consisted of twin 20 mm Type 99 cannon in dorsal, ventral and tail turrets; two 13 mm Type 2 machine-guns in nose turret and one flexible 13 mm Type 2 machine-gun on each side of the fuselage.
At least one of four built survived and was tested in the US. If this bomber had been expedited much earlier it would have proved a fine plane.
G10N1
The Fugaku or Mount Fuji was to be a super bomber on par with Germany's Amerika Bombers. Named "Project Z," Nakajima studied the requirements for an aircraft able to attack the continental United States from Japan on their own whim not due to official project request. His idea did draw interest from the military for further exploration.
Six 5,000 HP Nakajima Ha-505 36-cylinder radials were proposed but gestation on them was slow and six 2,500 HP Nakajima NK11A radials would have to be used to start. Dimensions are unknown but it would have had to have a wingspan similar to that of the six-engine Ju 390 at 165 feet and length of 112 feet. A crew of ten was suggested including one relief pilot.
The G10N1 would have cruised at 32,810 feet hauling its 11,023 lb. bomb load at 310 MPH with a range of over 12,000 miles! For shorter hops the payload could be as high as 44,092 lbs. With a top speed of about 400 MPH it would have been hard to catch. Even with the smaller engines speed performance would have been at least equal to the B-29's 342 MPH top speed with a 265 MPH cruise. Proposed armament was four 20 mm cannon- one in the nose, one in a tail location, and two in an upper fuselage turret.
This never made it of the drawing board.
Had the G10N1 been produced it could have bombed the western US. Long-range heavy bombers, if committed to in 1942, could have been counter attacking Allied islands by late 1944.