Nakadžima G8N Renzan [Rita]

Nakajima G8N Renzan - přehled verzí

Nakajima G8N (Renzan) - Version Overview


中島 G8N「連山」


十八試陸上攻撃機 - Jū hachi Shi Rikujō kōgeki-ki - 18-Shi Ground Attack Aircraft


Japanese name: 連山 - Renzan (Mountain Range)


Allied reporting name:"Rita"


Designation Aircraft Design - Description
Nakajima G8N1 model 11 Renzan four prototype bomber aircraft, powered by eighteen-cylinder Nakajima NK9K-L engines with Hitachi Type 92 turbochargers.
Nakajima G8N2 model 22 Renzan-Kai project, the aircraft was to carry up to three suicide bombs MXY7 Ohka model 33, powered by Mitsubishi MK10A Ru engines.
Nakajima G8N3 model 23 Renzan-Kai project, steel construction was to replace the deficient light metal alloys.


A total of 4 prototypes were produced.
Manufacture was carried out at 中島飛行機株式会社 - Nakajima Hikōki Kabushiki Kaisha, Koizumi

Sources used:
René J. Francillon Ph.D., Japanese Aircraft of the Pacific War, Naval Institute Press, Annapolis Maryland, Reprinted 1990, ISBN-0-87021-313-X
Tadeusz Januszewski and Kryzysztof Zalewski, Japońskie samoloty marynarski 1912-1945, tiel 2, Lampart, year 2000, ISBN 83-86776-00-05
Famous Airplanes of the World, No. 90, Nakajima navy heavy attack bomber Shinzan/Renzan′, Bunrindo Co. Ltd, 1977/10
author's archive
URL : https://www.valka.cz/Nakadzima-G8N-Renzan-Rita-t99712#365298 Version : 0

Nakajima G8N (Renzan) - 島 島 G8N 「連山」


H 試 陸上 攻 撃 機 - Jū hachi Shi Rikujō kōgeki-ki - 18-Shi ground attack aircraft


Combat name: 連山 - Renzan (Mountain range)


Allied reporting name: „Rita“


Aircraft history:


Quite often in various discussion forums we can meet with opinions why the Japanese naval air force did not have four-engine bombers. Opinions vary, but it is certainly not true that the command of the Japanese naval air force (ig 航空 本部 Kaigun Kōkū Hombu) did not want a heavy strategic bomber for its bombers. Already in the second half of the thirties, it tried to do so, but at that time such a demanding design was beyond the strength of Japanese designers and manufacturers, so the Imperial Naval Air Force indirectly purchased in 1939 in the United States a prototype airliner Douglas DC-4E. This prototype was examined in great detail and subsequently, based on this machine, the existing heavy bomber project was modified.

This project was created according to the specifications of 13-Shi from the summer of 1938, when the company 中 島 飛行 機 株式会社 - Nakajima Hikōki Kabushiki Kaisha (Nakajima) was entrusted with this very demanding task, but design work progressed very difficult and then designers and technicians were given the opportunity to thoroughly study the prototype of a modern four-engine machine, thus significantly accelerating the entire development of the bomber. We certainly cannot speak of this new aircraft as a mere copy, but on the other hand it is true that some components were taken over almost unchanged, for example the wings of the Japanese bomber were very similar to the original wings of the Super Mainliner, but with the difference that the bomber was designed as the mid-plane and the Super Mainliner was a low-flying aircraft. On the other hand, the hull design was completely inherent. The prototype of the new four-engine bomber G5N1 13-Shi was flown on April 10, 1941 and was soon assigned the combat name 深山 - Shinzan (Mountainside). The truth is, however, this aircraft was not very combat. Its design was to blame, untuned engines 中 島 護 11 型 - Nakajima NK7A Mamoru 11 did not reach the calculated performance and the total weight of the bomber, on the contrary, exceeded the calculated value by 20%. Reciprocally, this meant that the aircraft was heavily underpowered and gradually added further defects and shortcomings, which eventually led to Kaigun Kōkū Hombu stopped further work on this aircraft as a bomber and all six prototypes were after the replacement of Mamoru engines with a reliable Mitsubishi MK4B Kasei 12 rebuilt into the form of transport machines. Let's leave aside the question of whether the American design of the DC-4E or the Japanese modification was more to blame, but it was certain that the Nakajima G5N1 Shinzan never became a strategic bomber of the Japanese naval air force.


In the early 1940s, the Japanese Navy was preparing for war and the bombing units had to be equipped with a reliable long-range bomber, this aircraft was a twin-engine bomber Mitsubishi G4M Betty. The commander of the United Fleet, Admiral Isoroku Yamamoto always warned of a long and protracted war with the United States, his goal was to quickly and surprisingly do as much damage as possible, then seize new territories and force the enemy to acceptance of peace, such was his strategic plan, and he did without heavy four-engine bombers. The 1641 Shi specifications of 1941 required only higher performance twin-engine bombers, technical requirements were focused primarily on long-range, and based on this directive, the project Mitsubishi G7M1 Taizan was created. The following year, the Navy compiled the 17-Shi specifications, which again required only higher performance, and based on these guidelines, a twin-engine bomber project Kawanishi G9K1 was created.Kaigun Kōkū Hombu then assembled a control group, which became acquainted in detail with the projects of both companies, the result was that both projects stopped, neither of these projects was not included in the armament Kaigun Kōkū Hombu and the increasing demands of the naval air force had to meet more powerful versions.


With the protracted war, a turning point came in 1943 and the 18-Shi specifications were compiled, which again required a four-engine bomber, which was to be at least at the level of American bombers B-17 Fling Fortress a B-24 Liberator. The Japanese navy has already been forced to reckon with a long-term war, and a strategic bomber is an important tool for waging it. The possible advance of their own troops could no longer be based on quick and surprising attacks on the war, not very prepared and weaker enemy.


The basic specifications with technical requirements were handed over directly to Nakajima in February 1943, as we know, its designers and technicians had the greatest experience in the development and construction of six failed four-engine Shinzan aircraft. Kaigun Kōkū Hombu's technical officers thus saw the greatest preconditions for the successful construction of a new bomber. The management of the company decided that the development and construction will take place in the factory in Koizumi, the project was given the factory designation N-40, September 14, 1943 came to Koizumi the last details from the technical department Kaigun Kōkū Hombu . The specifications required a maximum speed of at least 592 km/h, with a load of 4,000 kg bombs to reach a distance of 3,700 km and a range of 7,400 km for reconnaissance missions or transfer flights. The height of 8,000 m was to reach a fully loaded bomber in a decent 20 minutes, armament was required cannon and any dead spots were to be covered by large-caliber machine gun fire, emphasis was also placed on passive protection of crew areas and fuel tanks.


The design team, led by engineer Kenichi Matsumuri, set to work, and the first prototype was completed in October of the following year. Kaigun Kōkū Hombu gave the new aircraft the combat name Renzan. In the factory hall in Koizumi stood a massive mid-plane with an all-metal structure, the whole structure was made of light metal alloys. The profile of the wings was laminar, which suggested that it would be a really fast machine. Propulsion units - eighteen-cylinder Nakajima NK9K-Lu Homare 24 were effectively supercharged Hitachi turbochargers type 92, engine cooling was forced. The aircraft carried 13,450 liters of fuel in self-locking tanks, the wall thickness of the fuel tank was 28 mm. The landing gear was of the bow type, during its construction, the Japanese designers were probably inspired by the landing gear of the captured bomber B-17E, which was carefully examined. The first takeoff was made on October 23, 1944, behind the factory Renzan sat factory test pilot Haruo Suemaca. The first prototype of the Renzan was never completely completed, on the one hand, the equipment was not installed, there was already a lack of aluminum alloys and some parts were not mounted, in addition, after a failure of brakes when driving soon damaged on the front of the fuselage. The turbochargers were not completely complete either, which also had frequent defects, several flights were supposed to be performed with the turbochargers disabled, if it really happened, so the engine power without supercharging had to be very low and it is certain that this prototype could not be performed performance tests. From January 1945, it was tested by naval pilots at the Oppama air base, where another accident occurred during landing, during which the rear part of the fuselage was damaged. The second prototype was completed in December of the same year, but was not flown until May 1945. The third and fourth prototypes were completed in March and June 1945, these prototypes were to be complete in terms of armaments and equipment, but it is uncertain whether all tests.
According to the original plans, sixteen pre-production and forty-eight series-produced aircraft were to be produced this year. However, the production plan was quite delayed, despite the accepted and immediately implemented modifications, which were to reduce production intensity. The biggest delay was caused by American air raids (during which the third prototype was destroyed), other problems were brought by so far unreliable turbochargers, which needed to be debugged and especially the lack of aluminum alloys. At the end of the war, Japan faced a critical shortage of almost all non-ferrous metals. The construction of the G8N1 heavy bomber was very demanding in this respect, consuming so many light alloys that it was enough to build at least four much-needed fighters Mitsubishi A6M5 Reisen (Zero). This large consumption of highly deficient materials eventually led Kaigun Kōkū Hombu to make the difficult decision to end the development of the four-engine bomber on June 13, 1945. Japan was on the defensive, and fighter production had a disproportionately higher priority than the introduction of strategic bomber.


The factory team of designers still submitted two of their projects, which were not implemented, the first of these projects was to be a modified Renzan, which was to carry three suicide planes MXY7 Ohka type 33. Using a Renzan-type bomber, transporting the Ohka to the target area would become more reliable and faster. The project included a change in power units, the aircraft was to be powered by Mitsubishi MK10A-Ru engines, which were more powerful and perhaps more reliable, this project was marked as G8N2 model 22. The second project marked G8N3 model 23 was aimed at saving aluminum alloys, the supporting structure and most of the cover panels on the fuselage were to be made of steel. The weight of the empty aircraft was to increase by up to 3,000 kg, but the performance was still maintained at an acceptable level, according to calculations.


The code name Rita was given this type only after the surrender of Japan. The fourth prototype Renzan was transported to the United States for testing and actually flew there. The Americans rated it as slightly superior to all versions of the B-17 and B-24, but The Boeing B-29 Superfortress was superior in performance to the Japanese aircraft in tests.



Sources used:
René J. Francillon Ph.D., Japanese Aircraft of the Pacific War, Naval Institute Press, Annapolis Maryland, Reprinted 1990, ISBN-0-87021-313-X
Tadeusz Januszewski and Kryzysztof Zalewski, Japońskie samoloty marynarski 1912-1945, tiel 2, Lampart, rok 2000, ISBN 83-86776-00-05
Famous Airplanes of the World, No. 90, Nakajima navy heavy attack bomber Shinzan/Renzan ′, Bunrindo Co. Ltd., 1977/10
Jaroslav Schmidt, Fighter and Bomber Aircraft of Japan, Part 2, Fraus Publishing House Pilsen, year 2000, ISBN 80-7238-077-X.
Václav Němeček, Military Aircraft Part 3, Our Army, Prague 1992, ISBN 80-206-0117-1
Vaclav Nemecek, L + K No. 9/1974, Aircraft 1939 - 45, Nakajima G8N1 Renzan
http://www.combinedfleet.com/ijna/g8n.htm
http://www.airwar.ru/enc/bww2/g8n.html
pro-samolet.ru
www.world-war-2-planes.com
author's archive
URL : https://www.valka.cz/Nakadzima-G8N-Renzan-Rita-t99712#365305 Version : 0
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