After heavy defeats in mid-1942, it became clear to many discerning people in Japan that the war would be lost. They, of course, could not imagine how: to imagine the burning of one city after another, hundreds of crews of bombers in one sortie, having orders to massively destroy civilians, nuclear strikes, a mine blockade with the telling name "Starvation" (famine) in 1942- m was not easy, as was the occupation of the islands by the gaijin with the loss of Japan's sovereignty. But in principle, everything was clear. Everything was especially clear to those who, by virtue of their social status, had access to information about the unfolding American military programs and their scale.
Project Z
The head of the Nakajima aviation concern Chikuhei Nakajima was quite an astute person, very well acquainted with American industrial potential, and he was a very informed person, he was, for example, aware of the fact that the Americans were making an intercontinental strategic bomber (in 1946, he became known as the Convair B-36. The Americans stopped funding for this project twice, so the plane "did not have time" for the Second World War, but in 1942 it was not obvious). He also knew about the future Japanese nightmare Boeing B-29 Superfortress.
In November 1942, Nakajima gathered several leading engineers of the concern in the club of the same name and explained in detail to them the prospects for Japan in the ongoing war. From Nakajima's point of view, there was only one way to avoid defeat - Japan should have been able to bomb American territory. For this, he said, it was necessary to quickly create and start producing an intercontinental strategic bomber capable of striking the United States from the Japanese islands.
It is known that in the same year, Nakajima tried to present his ideas to both the representatives of the imperial army and representatives of the imperial navy, but did not receive support, and decided to start acting independently. It is not known only whether this was before or after the November meeting.
Nakajima told the engineers who were to work on the project of the Japanese "strategist" that the aircraft would need engines with a capacity of at least 5000 hp. This was an extremely bold demand - at that time the Japanese did not have anything even remotely close in terms of parameters. However, Nakajima knew that next year the experimental 18-cylinder aircraft engine "Nakajima" Ha-44 (Nakajima Ha-44), capable of producing 2,700 hp with sufficient air pressure, would see the light of day. at 2700 rpm Nakajima figured he could quickly create a pair of two of these motors, driven by coaxial counter-rotating propellers. Nakajima believed that these engines would enable the future aircraft to evade American fighters.
From the beginning of 1943, the engineering group, in complete secrecy, began development. The chief engineer of the concern Satoshi Koyama became the chef of the entire program. The development of the fuselage was led by Shinbou Mitake, who previously worked on the G5N1 Shinzan aircraft. Kiyoshi Tanaka headed the work on the engines. The engine group included engineers Nakagawa (creator of the Nakajima Nomare family of aircraft engines), Kudo, Inoi and Kotani.
The group was given the intricate name "Team for the Study of Victory in the Game and the Protection of the Japanese Skies", and the aircraft project - "Project Z".
To determine the appropriate appearance of the aircraft, the group completed several projects, replacing each other, each for the Ha-54-01 engine developed by the "dvigelists", which was the same pair of experimental Ha-44s "invented" by Nakajima.
During the first half of 1943, 4-engine variants were studied and rejected.
In the middle of 1943, two six-engine projects remained, which were seriously different from each other, both in layout, and in the tail unit and in the type of chassis used.
The engineers also considered the option with the Ha-44 engines, in case the Ha-54-01 did not work out, and in the latter case, not only the bomber was worked out, but also the transport, as well as the "gunship" armed with several dozen machine guns to defeat American interceptors massive fire.
In June 1943 "Project Z" took its final appearance at that time - it was supposed to be a truly monstrous six-engine aircraft, with six engines of 5000 hp each.
The project provided for a wide fuselage with two decks, sleeping places, and all-round firing for protection from fighters. All options except the bomber were excluded from consideration.
It was assumed that the aircraft will have the following characteristics:
Wingspan: 65 m
Length: 45 m.
Height: 12 m.
Wing area: 350 sq. meters.
The distance between the main (underwing) landing gear: 9 m.
The capacity of the fuel tanks in the fuselage: 42 720 liters.
The capacity of the fuel tanks in the wings: 57,200 liters.
Wing loading: 457 kg / sq. meter.
Empty aircraft weight: 67, 3 tons.
Maximum takeoff weight: 160 tons.
Engines: Nakajima Ha 54-01, 6 x 5,000 hp takeoff, 6 x 4, 600 hp at an altitude of 7, 000 meters.
Propellers: 3-blade, coaxial, opposite rotation, for each engine, diameter 4, 8 m.
Maximum speed: 680 km / h at an altitude of 7000 m.
Service ceiling: 12480 m.
Takeoff run: 1200 meters.
Range: 16,000 km with 20 tons of bombs (possibly referring to dropping them halfway through the route).
Finding a customer
After the project configuration was frozen, Nakajima again found a way to present it to the army and navy. Now "Project Z" has received the name "Plan of strategic victory in the game." At that time, the army and navy were considering several projects of bombers capable of reaching the United States: Kawanishi TB, Kawasaki Ki-91 and Tachikawa Ki-74. The emergence of Project Z immediately made him the favorite in the race, although the Kawanishi position was strong in the navy. The Army and Navy, impressed by the proposed parameters for Project Z, formed a special committee to develop it, providing Nakajima with several dozen scientists and engineers to reinforce the project team.
The aircraft received the index G10N and its own name Fugaku (Fugaku), which means "Mount Fuji".
Soon, the committee for its development also received a similar name - "Fugaku Committee". A little later, Nakajima himself will be appointed chairman, and he will receive full power over the project. The committee included representatives from the Nakajima concern, the Imperial Army Aviation Technology Research Institute, the Central Aviation Research Institute, the Tokyo Imperial Institute, and Mitsubishi, Hitachi and Sumimoto corporations.
In the final version, the plane was supposed to take off from a specially built airfield in the Kuril Islands, attack industrial targets in the United States, fly across the Atlantic, land in Germany, where the crew would rest, the plane would undergo maintenance, refuel, receive bombs and make a return flight.
In March 1944, the Kavanishi TB dropped out of the competition for the future intercontinental bomber. Only Fugaku remained.
Approximate parameters of "Kavanishi" TB:
Wingspan: 52.5 m
Wing area: 220 sq. meters.
Range: 23,700 km with 2 tons of bombs.
Service ceiling: 12,000 m
Crew: 6 people.
Armament: 13 mm machine guns - 4 pcs.
Maximum speed: 600 km / h at an altitude of 12,000 m.
Maximum takeoff weight: 74 tons.
Takeoff run: 1900 meters.
Engines: presumably upgraded Mitsubishi Ha42 or Ha43, 4 pcs.
And then Fugaku started having problems. In February 1944, customers came to the conclusion that the engine capable of making the giant fly would not be completed in time. By order, Nakajima was required to rework the project for a more realistic type of engine.
The trouble was that no other engine was suitable for such a huge machine.
Choice of engines
"Nakajima" Ha 54-01 was conceived as a motor with exorbitant parameters. Suffice it to say that no one has ever built a piston aircraft engine with such parameters. The most powerful piston aircraft engine in history - the post-war Soviet VD-4K had a power of 4200 hp. and it was a much more advanced engine than the planned Ha 54-01. The Americans did not master this either - their superbomber Convair B-36 was powered by Pratt & Whitney R-4360-53 Wasp Major aircraft engines with a capacity of 3800 hp each. Likewise, the number of cylinders that Nakajima wanted to see on his creation was unprecedented - 36, in 4 "stars" with 9 cylinders each. At the same time, each of the 18-cylinder twin blocks worked on its own propeller. To provide the required air pressure in the intake manifolds, a supercharger with a turbine wheel diameter of 500 mm was provided. But Japan had no experience with superchargers - neither turbochargers nor any type of drive supercharger. The problem was the potential vibration of a long engine, the problem was to ensure an even distribution of the fuel / air mixture across the cylinders in the intake manifold of an incredibly complex shape.
A separate problem was cooling, which was provided for by air on the motor. Air supply to such a tightly packed engine promised to be very difficult. The engineers involved in the project immediately saw these pitfalls, but Nakajima himself stubbornly stood his ground, saying literally: "Don't settle for even one horsepower less than five thousand."
But it didn't work out against the realities. When "Fugaku" triumphantly defeated all competitors, the design team was already reworking the project for more realistic motors.
The aircraft was reduced in size and lightened, coaxial propellers disappeared from the project, they were replaced by ordinary four-bladed ones, claims for the ceiling, maximum range, maximum bomb load, but increased defensive armament - now the aircraft could not "run away" from US interceptors and had to fight them. For this, on all the following projects, as many as 24 automatic cannons with a caliber of 20 mm were provided.
The engineers offered two options. The first - with the Nakajima Xa44 engine, half of the planned Xa54-01, the second with the newly created Mitsubishi Xa50 engine.
The latter had an extremely original design, and the Japanese turned out unexpectedly quickly. Since 1942, Mitsubishi has been tormented by an engine codenamed A19 - a 28-cylinder engine, "recruited" from 4 "stars" with 7 cylinders in each. It was assumed that its power would be about 3000 hp. With the calculated power, everything worked out, but even on paper it was clear that the cooling of the "rear" cylinders would not work. The project was canceled, but the mistakes made in the design of the A19 helped Mitsubishi to create a simpler engine in just a year - two "stars", but … 11 cylinders!
The engine had a steel cylinder block, air cooling, steel cylinders and aluminum cylinder heads, each having one inlet and one exhaust valve. It was assumed that the engine will have a two-stage supercharging - the first stage is a turbocharger, and the second, "booster" - a supercharger with a gear drive. However, the prototypes had only a supercharger - turbochargers were the "weak point" of the Japanese aircraft industry. The first engine had such vibrations that it collapsed during tests in April or May 1944, but the next three have already shown themselves to be normal - with insufficient boost pressure, they could produce 2700 hp each, if it was possible to achieve the full design boost pressure, then the power would rise to 3100 hp In the end, at the end of the war, one of the tested engines produced 3200 hp.
Taking into account that the Nakajima Xa44 had already been tested, the committee was offered two versions of the Fugaku - one with the Nakajima engine, the second with the Mitsubishi engine, which had already received the X50 index by that time.
Specifications:
Airplane with engines Xa44 (6 pcs.):
Wing area: 330 sq. meters.
Range: 18,200 km with 10 tons of bombs or 21,200 km with 5 tons of bombs.
Service ceiling: 15,000 meters.
Maximum speed: 640 km / h at an altitude of 12,000 m.
Maximum takeoff weight: 122 tons.
Takeoff run: 1700 m.
Engines: "Nakajima" Xa44, 2500 hp takeoff, 2050 hp at a height (not known exactly).
Airplane with Xa50 engines (6 pcs.):
Wing area: 330 sq. meters.
Range: 16,500 km with 10 tons of bombs or 19,400 km with 5 tons of bombs.
Service ceiling: 15,000 meters.
Maximum speed: 700 km / h at an altitude of 12,000 m.
Maximum takeoff weight: 122 tons.
Takeoff run: 1200 m.
Engines: "Nakajima" Xa44, 3300 hp on takeoff, 2370 hp at an altitude of 10,400.
With such engines, the construction of the aircraft was already realistic. By that time, in the summer of 1944, in Mitake, Tokyo Prefecture, not only had a factory for the construction of the first Fugaku been equipped, but the equipment had already been delivered there, and, according to some sources, the manufacture of fuselages had begun.
But the project did not have long to live: on July 9, 1944, Saipan fell, and the Americans received territory from which the B-29 could attack targets on the Japanese islands. The very first raids of the Americans showed that the Japanese aviation could not cope with this aircraft - the "fortress" that dropped the bombs was corny faster than the Japanese fighters and surpassed them in height. In such conditions, the Japanese did not find any other way out but to close all resource-intensive offensive programs and focus on protecting their airspace - as we know, unsuccessfully. Ahead of them awaited the nightmare of the American policy of destroying cities, total mining and nuclear bombs.
Soon, all the equipment for the production of "Fugaku" was dismantled. The tests of the Xa44 and Xa50 engines continued without any connection with the project.
By the time of the American invasion, only the documentation and one Ha50 remained unharmed by the bombs. The documentation was later lost along with the entire Japanese engineering school, and the Americans planned to take the last Ha50 to the United States for study, but then changed their mind and buried it in the ground with the help of a bulldozer. There he lay until 1984, when he was accidentally found during the expansion of Haneda Airport (Tokyo).
The engine was almost completely destroyed by corrosion, but the Japanese were able to mothball it, stopping the destruction and today its remains are on display at the Museum of Aviation Science in Narita.
This is all that remains of one of Japan's most ambitious aviation projects.
Was the project real?
To assess whether the Fugaku project or another Japanese intercontinental bomber was real, it is necessary to analyze not only technical, but also organizational factors. In fact, the project started in early 1943, and until the fall of 1942, the Japanese did not raise the issue of bombing US territory. But the war began at the end of 1941, and the decision that it might have to be started was made even earlier.
We know that the preliminary design for "realistic" engines was ready in the summer of 1944. This means that with a "shift" in time and if work on the aircraft would have begun, for example, in the summer of 1941, the same project would have been ready at the end of 1942, when before the first American bomb attack on Japan there would be two more years left. In those days, airplanes were simple, they were designed quickly and put into series also quickly.
Technically, you have to understand that the "Fugaku" was a primitive aircraft. Its level of technology cannot be compared categorically to either the B-29 or the B-36. In terms of its technical level, this aircraft was only slightly superior to the B-17, and even then in terms of the construction of a large fuselage. In fact, the Japanese planned to build an intercontinental six-engine aircraft, based on the technologies of the early forties, and at the average world level of technology, and not on the much more advanced American one. And in fact, to make Fugaku realizable, all that was needed was an engine. The Mitsubishi Xa50, proactively built in less than two years, proves that the Japanese could have made an engine. Naturally, then it would be necessary to simplify the project once again - so 24 cannons of 20 mm caliber look unrealistic for an aircraft with such a low power-to-weight ratio, apparently, some of the weapons and firing points would have to be sacrificed, the crew would have to be reduced, the idea of bringing 5 tons of bombs to the United States would have to be abandoned. limiting ourselves to one or two …
The last stumbling block is pressurization - it is known that neither Germany, nor the USSR, nor Japan could resolve the issue of reliable pressurization during the war, and without this it is impossible to fly at high altitudes, with thin air. The Americans had reliable turbochargers, and no less reliable mechanical ones, but, as many enthusiasts of technical history are sure, the Japanese would not have had time to make a reliable supercharger due to their mind, waging a difficult war.
The problem with skeptics, however, is that they did it, again towards the end of the war, and again, starting very late.
At the end of 1943, Nakajima began and in mid-1945 completed the creation of the Japanese B-17 - the Renzan bomber, or the entire Nakajima G8N Renzan.
This four-engined aircraft was powered by the Nakajima NK9K-L engine, based on the atmospheric Nomare range, which also gave birth to the experimental Xa44. Recycling of atmospheric engines for supercharging is a thankless and difficult task, and even the Hitachi 92 turbochargers themselves turned out to be "raw". But - and this is very important - on the last of the prototypes, the very one that the Americans later brought to their territory, the turbochargers worked "perfectly"! The Japanese did it! And this is the last obstacle that would prevent them from creating a high-altitude high-speed aircraft if necessary.
It was only necessary to start earlier.
It should be understood that although America would still remain immeasurably stronger than Japan, the latter's ability to bomb the United States could significantly affect the course of the war - strikes on shipyards on the US Pacific coast would change the timing of the entry of new warships into the US Navy, and the possibility of a phosphorus storm somewhere in Seattle might have deterred Americans from the targeted massacre of civilians in 1945. Moreover, it would be technically difficult to implement, because the Japanese, having aircraft with such a range and a large bomb load, could effectively destroy their bases in the Pacific Islands, making bombing Japan a very difficult matter. And if we bear in mind the work on the creation of nuclear weapons, which was carried out by Japan, then the number of options for the outcome of the Second World War is becoming very large. However, the Japanese would not have been able to buy enough time for their bomb by bombers alone.
One way or another, the lack of understanding of the need for strategic aviation caused great harm to the Japanese. Just like the USSR, just like Germany. This lesson from the history of the failed Japanese "strategist" is still relevant today.
