Nakajima G8N "Renzan" (Rita) #3 - Extra info & Video

Apart from the Wiki entry, HERE, below is information we translated from FAOW.

Chief designer of the Nakajima G8N "Renzan" was Matsumura Kenichi who graduated from Tokyo University in 1932 and joined Nakajima in 1934. He designed the Nakajima LB-2 (note the wrong way his name is written in the Wiki entry) and later the Nakajima G5N "Shinzan", the Nakajima B6N "Tenzan" and was involved in the Nakajima G10N "Fugaku" design; in effect in all the Nakajima aircraft of the "mountain series". He also participated in the initial steps of the "Kikka" project.

From 1950 he worked in US bases in Japan remodelling American aircraft. He died in April 1951 in an accident. He was only 42 years old.    

 

The order for the development of the "Renzan" was given during a critical war period for Japan, therefore, from the beginning, the time consuming process of building numerous prototypes and extensive testing was out of the question. The design was to be mass produced as soon as possible. With the above in mind not even one day was to be wasted and Matsumura put together a development plan along the following important points. 

 

1. Reliable data was to be used for the engines and the overall construction of the aircraft.

2. Everything was to be researched and tested thoroughly before the beginning of the construction of the aircraft.

3. "Renzan" was to be built with the present, not the future, in mind. Meaning that currently available technology was to be incorporated without relying on future developments and improvements.

4. The designated weight should not be exceeded.

5. Special consideration should be taken to make the fuel tanks leak-proof.

6. Superchargers should be installed

7. Special attention should be payed to the defencive armament positions, predicting whatever imperfections and problems because in the past there were numerous problems with other aircraft designs.

8. The experience with other large aircraft should be put into use to design the fin and the tail surfaces but always keeping everything small. Also, various tail designs/configurations should not be tested but once a design is decided effort should be put only to improve it if necessary.

9. The aircraft should be built using immediately available material that will continue to be available when the design will be put into production. 

 

In hindsight the above may sound very logical and natural but they reflect the problems the Japanese designers had with other aircraft which took too long to be designed and tested and when they were put into production they were soon obsolete.

 

Development progress until the completion of the first prototype

   

End of 1942	IJNAF unofficially ordered the N40 plan. "N40" was the designation for the experimental design. Within Nakajima the aircraft was nicknamed "G8" (from the G8N1). The name "Renzan" was given around the middle of 1944, after the first prototype was completed and around the time the unofficial order for the pre-production aircraft was given.
March 5, 1943	N40 first research meeting
April 2	Discussion of the IJNAF specifications
May 12	Test of the wooden mock-up of the fore machine gun mount
May 30	Preliminary test of the wooden a/c mock-up
June 12-16	The IJNAF specifications were preliminary discussed between the eight departments responsible for the development of the project.
June 24-28	Second meeting with two of the above mentioned departments
July 29-30	First test of the wooden mock-up
August 14	General inspection of the development progress by the IJNAF
September 3-4	Second mock-up test
September 14	Received by the IJNAF the official order
September 30	Third mock-up test
December 15	Sixth mock-up test
April 29, 1944	Beginning of the construction of the first prototype
June 13	Material test
June 14-15	First structure test. A/c 50% complete
July 30	Second structure test. A/c 75% complete
September 5-6	Third structure test. A/c 90% complete
October 1	Test of completed aircraft
October 10	Taxing test
October 23	First flight. Small damage during landing
October 31	Meeting regarding the radioman's position
November 10	Fore armament research meeting
December 5	Fore armament wooden test
December 25	Nakajima acceptance ceremony
January 12, 1945	Aircraft delivered to the IJNAF. Eighth flight

As mentioned above On December 25, 1944 an acceptance ceremony was held in the Nakajima factory in Koizumi. The video below from UTube shows this ceremony.

 

 

The very first prototype after it was delivered to the IJNAF, flew to Oppama base, Yokosuka, where it was speed tested. Then from May 1945 it was tested in Misawa, Aomori prefecture.

The history of the four prototypes is as follows:

 

1st prototype	Finished: end of Sept. 1944	1st fight: Oct. 23, 1944
2nd prototype	Finished: Dec. 29, 1944	1st flight: Apr. 12, 1945
3rd prototype	Finished: Mar. 26, 1945	1st flight: June ?, 1945
4th prototype	Finished: June ?, 1945

 

The 3rd Prototype was burned and destroyed during an air raid in Koizumi. The 1st and the 2nd were in Misawa at war's end while the 4th was in Koizumi partially incomplete. Parts from the 1st and 2nd were used to complete it and was sent to the States for evaluation. The 1st and 2nd prototypes were then scrapped. In April 1945 there were heavy air raids everywhere in Japan and the "Renzan" design team evacuated to the Girl's Highschool in Kumagaya, Saitama prefecture. Various designs and documents were damaged while there and at the end of the war all blueprints and documents were burned in Nakajima.