Nakajima B4N1 Torpedo Bomber

jzichek

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Has anyone ever come across a three-view drawing or more photos of the Nakajima B4N1 of 1932?


b3n-i.jpg



This apparently is the only known image of the aircraft. Hyperscale ran an article on a fantastic scratchbuilt model of this obscure prototype several years back; I contacted the modeler, Frank Mitchell, for a copy of the plans he used for the project, but he never responded. I'm wondering if more information has emerged in the Japanese press in the intervening years. It's quite a distinctive looking bird and it would be great to find more information on it.


-Jared
 

Stargazer2006

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A fascinating aircraft, indeed, unlike any other... Depending on which Japanese source you look at, it was built either in 1934 or in 1936, in one or two prototypes. Given the absence of photos, I'd go for one prototype only, personally. Scarcity of photos can sometimes depend on the loss of a prototype, but when there are two, you usually find more pics than that!
 

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I have only seen this one photo too, but I can give a somewhat better photo.
Source is: ILLUSTRATED WARPLANE HISTORY, THE XPLANES of IMPERIAL JAPANESE ARMY & NAVY 1924-1945, illustration & Text Shigeru Nohara, Green Arrow Publication, Tokyo, 1999/9/20, ISBN-7663-3292-XC0076


I'm sure blackkite could help you with this, there is some text in the above source but I cannot translate it.
 

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blackkite

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jzichek said:
Has anyone ever come across a three-view drawing or more photos of the Nakajima B4N1 of 1932?

This apparently is the only known image of the aircraft. Hyperscale ran an article on a fantastic scratchbuilt model of this obscure prototype several years back; I contacted the modeler, Frank Mitchell, for a copy of the plans he used for the project, but he never responded. I'm wondering if more information has emerged in the Japanese press in the intervening years. It's quite a distinctive looking bird and it would be great to find more information on it.


-Jared
Hi Jared! I will try to find 3-side view. Please wait for a week.
 

taildragger

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Stargazer2006 said:
Scarcity of photos can sometimes depend on the loss of a prototype, but when there are two, you usually find more pics than that!

It can also depend on whether the photos were stored in a facility on the 20th Air Force's target list, regardless of how many prototypes were built.
 

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I found the same image in 'Japanese Aircraft 1910-1941' by Robert C Mikesh & Shorzoe Abe, Putnam 1990. They identify the aircraft as 'Experimental 7-Shi Carrier Attack Aircraft (B3N1) (Company designation Y3B)'.

Designed by Takao Yoshida in response to an order for a replacement for the Mitsubishi Type 89. Mitsubishi also received an order; they produced the type 3MT10, the only example built crashing in February 1934. Mikesh and Abe partly attribute failure of either design to attain production to the lack of a mature suitable engine.

Single-engine carrier attack bomber. Fuselage of welded steel tube construction, metal frame wings, with fabric covering. Rearward folding wings for stowage. Crew of three; pilot, bombardier/navigator and radio operator/gunner.
700 hp Nakajima Hikari 2 nine-cylinder air-cooled radial engine, driving a three-bladed metal propeller.
One dorsal flexible 7.7mm machine-gun.Bomb load: one 800kg torpedo, or one 800kg bomb, or one 500kg bomb, or two 250 kg bombs or equivalent.
Span 14m (45ft 11¼in); length 10m (32ft 9½in); height 3.80m (12ft 5½in); wing area 50 sq m (538.213sq ft).
Empty weight 2,000kg(4,409lb); loaded weight 3,800kg (8,377lb); wing loading 76kg/sq m (15.5lb/sq ft); power loading 5.4kg/hp (11.9lb/hp).
Maximum speed 120kt (138mph); minimum speed 50kt (57.5mph); climb to 3,000m (9,843ft) in 12min; service ceiling 5,500m (18,044ft); endurance 6hr.
Two built in 1933.

Mikesh and Abe also refer to the Nakajima B4N1 which was designed for the later 9-Shi competition; two were built in 1936. The competition was won by the Kusho B4Y1.
 

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From the various Japanese sources I've seen (all showing the same image) it is definitely the B4N, not the B3N.
 

Arjen

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I just have one source for the B3N1 designation: Mikesh & Abe. The book may be in error, but apart from the image, the aircraft's configuration is described in some detail.
...non-staggered biplane had its wing attached to the fuselage in both gull and inverted-gull wing fashion, forming an X at the fuselage.
If they are in error, it's not simply a case of mismatched image caption.

The Nakajima B4N1 is also mentioned by Mikesh & Abe, unfortunately, they don't provide an image. However:
Both the Kusho B4Y1 and the Nakajima B4N1 had quite similar exterior lines.
The Kusho B4Y1 is better known as the Yokosuka B4Y1.

Image source wikipedia
 

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blackkite

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Hi Jared! Sorry I can't find any drawings or new pictures of Nakajima B4N1 in my books and Japanese internet site.
It's very very hard problem to find it even for Japanese people.
 

blackkite

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I only find this drawing of Nakajima B4N1.
The B4N1 model which Jared showed us is very surprising one for me.
Engine:Nakajima Hikari 1 type air cooling radial engine, 660hp(3,500m), 820hp(take off), crew:3, Completed 1936,
Wooden propeller diameter:3.5m, Main dimension:unknown, The armament:7.9mm machine gun×2(nose fixed and back seat one rotating),
torpedo:800kg or bomb:500kg, Wings were folded aftward.
The performance was not satisfactory for for the IJN.
Source:Imperial Japanese Navy Warplane, Green Arrow publication, ISBN4-7663-3161-3 P3000E, May 1994
 

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blackkite

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BTW my No2 bible "ENCYCLOPEDIA OF JAPANESE AIRCRAFT 1900-1945 (NAKAJIMA)" says that it's Nakajima 7-shi torpedo bomber(B3N1 or Nakajima's domestic code Y3B) designed by Takao Yoshida,completed in 1933. :-[
Also wikipedia says....
http://en.wikipedia.org/wiki/Nakajima_B3N

And.....

http://www.scribd.com/doc/37093223/The-Nakajima-B3N1

And also my No2 bible says that Nakajima 9-shi torpedo bomber(B4N1,2 plane completed in 1936) were Kugisho(Yokosuka) B4Y1 like aircraft with Kotobuki(寿) 3 engine and Hikari(光) 1 engine designed by Takao Yoshida and Yasuo Fukuda.

http://www.nags-gallery.com/gallery/b4y1.htm
 

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Stargazer2006

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blackkite, there seem to be a LOT more sources pointing to this Y3B as being the B4N rather than the B3N. Who's wrong? Who's right?

Also:

1°) I haven't been able to find a single picture of the B3N. Do you have any?
2°) In one source I found that the B4N had been ordered as B3N then modified as B4N. Do you have a detailed description of both so we can see how similar they were meant to be?
2°) Several sources talk of TWO prototypes, others talk about only one. Do you have a definitive answer to that?

Thanks!
 

blackkite

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Stargazer2006 said:
blackkite, there seem to be a LOT more sources pointing to this Y3B as being the B4N rather than the B3N. Who's wrong? Who's right?

Also:

1°) I haven't been able to find a single picture of the B3N. Do you have any?
2°) In one source I found that the B4N had been ordered as B3N then modified as B4N. Do you have a detailed description of both so we can see how similar they were meant to be?
2°) Several sources talk of TWO prototypes, others talk about only one. Do you have a definitive answer to that?

Thanks!

Hi! I am embarrassed now. :-[
 

Arjen

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Blackkite: don't feel too embarassed. There are two creditable sources that state the B4N1 and B4Y1 were similar designs.
- Nozawa, Hashimoto, Ogawa: 'Encyclopedia of Japanese Aircraft 1900-1945. Vol. 5: Nakajima' (Encyclopedia of Japanese Aircraft series, No. 5; Shuppan-Kyodo Publishers, 1966
- Mikesh, Abe: 'Japanese Aircraft 1910-1941'; Putnam, 1990.
The B4Y1 is quite unlike the aircraft in Jared's picture.

Searching for pictures of the B3N1/B4N1, there's one picture that keeps turning up: the one Jared posted, alternately labeled B3N1 or B4N1. Most confusing.
As far as I'm concerned, the jury's still out on the precise designation of the aircraft. If I had to choose, I'd go for B3N1 - but I'm not sure. Two creditable sources claiming 'similar' designs for B4N and B3N B4Y might be caused by the later book book simply repeating the earlier book - that, or the writers had access to similar sources. In turn, how trustworthy those sources were, I don't know. To me, the X-winged aircraft 'feels' older than the B4Y1, but that's entirely subjective.
 

blackkite

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Many thanks Arjen! I could not sleep well last night. ;D
 

blackkite

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Never mind Star! It's not your responsibility. ;)
 

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jzichek said:
Has anyone ever come across a three-view drawing or more photos of the Nakajima B4N1 of 1932?


b3n-i.jpg



This apparently is the only known image of the aircraft. Hyperscale ran an article on a fantastic scratchbuilt model of this obscure prototype several years back; I contacted the modeler, Frank Mitchell, for a copy of the plans he used for the project, but he never responded. I'm wondering if more information has emerged in the Japanese press in the intervening years. It's quite a distinctive looking bird and it would be great to find more information on it.


-Jared


Hello Jared,
I was not much confident about finding the drawings, after three moves and a pair of computer crashes, but I succeed...
Immediately after the HS feature, back in 2004, I asked Frank Mitchell - a great guy - for the drawings and he snail-posted me some photocopies of those he used as a basis to scratchbuild that model.
He received the drawings via fax from Bob Mikesh, so the quality is not top notch, but I hope they will suffice.
Best Regards
Ermeio
 

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ermeio

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I think the drawings are from a japanese source
if we are lucky enough someone around here has the original in colour.
Best regards
ermeio
 

Arjen

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*Nice* Thank you for sharing.
 

Stargazer2006

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WONDERFUL!!! Thanks so much for sharing!

Have you noticed that this says "B4N1"? Not B3N1!!
 

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Wow!!! Fantastic I can't believe this 3d view are available. Thanks a lot!!! :D :D :D
 

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Thanks very much for sharing these Ermeio! First three-view I've ever seen of this aircraft. A rare treat!
 

blackkite

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ermeio said:
I think the drawings are from a japanese source
if we are lucky enough someone around here has the original in colour.
Best regards
ermeio
Yes I think so. It's the first time for me to see such a drawing. I want to see the source Japanese book.
If it's B4N1, we want to see B3N1's picture and 3 side view drawing.
Anyway thank you very much for sharing us such a rare one.
 

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blackkite said:
ermeio said:
I think the drawings are from a japanese source
if we are lucky enough someone around here has the original in colour.
Best regards
ermeio
Yes I think so. It's the first time for me to see such a drawing. I want to see the source Japanese book.
If it's B4N1, we want to see B3N1's picture and 3 side view drawing.
Anyway thank you very much for sharing us such a rare one.

Blackkite Do you see any clue about the book in the pictures? I hope you can found the source. Maybe we can see some drawings of Nakajima 6/7/8-Shi Dive bomber too :D
 

blackkite

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I checked this surprising 3-side view, but I can't find any drawer's sign. Why? Curious.
 

Stargazer2006

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I am currently working at creating a three-view plan of the Nakajima B4N1 thanks to the wonderful material that has been shared here.

Here is the profile view. Depending on how this profile is received, I will also provide the top and front views.

I had to make choices that may not necessarily be the right ones, so I welcome any suggestions, corrections and criticism to help make it better!
 

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theponja

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Wow! That's was fast Stargazer. Great work , I'm just wondering about ... well I'm not a native English speaker and it's late ... about to many , well "lines" in the tail.
 

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Alcides said:
..I'm just wondering about ... too many , well "lines" in the tail.

Hard to tell, I think. Those "lines" actually are the stringers in the fabric covered section,
shaping the curved cross-section. More stringers mean, that the tail matches the shape
ofn the metal covered forward part better, improving aerodynamics, but at the price of
increased weight. Which was the compromise, the designers came here to ? Quite often
those stringers just spread out to the last frame and the actual fin section is shaped
differently, sometimes again with metal sheet (I've attached an example from http://richard.ferriere.free.fr/).
If spaced evenly along the perimeter, the distances between the stringers would appear
biggest in the middle, reducing more and more to the upper and lower edges of the section
in the side-view.
But there are always counter-examples to those rules and without more sources it depends
on personal interpretation. Good work, Stargazer !
 

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Nick Sumner

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Ermeio - thanks for this, this aircraft has long been an enigma!
 

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Hello
I have another threasure to share: back in 2004 Frank Mitchell sent me also some sketches he made himself to scratchbuild the model.
Yesterday I have tried to to write him to have the permission to share them, but I have had no response - I think his address is no longer valid.
I will share them as a tribute to the craftmanship of this master scratchbuilder, and I promise that if I ever will succeed in contacting him I will send him a pair of plans of the ugliest and strangest obscuriest aircraft about which I have documentation.
I invite you to thank this man with me, also for bearing light about those obscure aircraft like the B4N1.
best regards
ermeio
 

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ermeio

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Stargazer2006 said:
I am currently working at creating a three-view plan of the Nakajima B4N1 thanks to the wonderful material that has been shared here.

Here is the profile view. Depending on how this profile is received, I will also provide the top and front views.

I had to make choices that may not necessarily be the right ones, so I welcome any suggestions, corrections and criticism to help make it better!

Great - I hope the sketches that I enclosed in my post will help you to produce a nice 3-view drawing of this aircraft-
Pity that i had no time in these years to scratchbuild the model, due to the pressure from my job and family.
It's in the stash of the to-do
greetings
 

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Thanks again ermeio! I believe Frank said in his article on Hyperscale that he found some problems with the plans he got through Mikesh and had to draw up some of his own; these must be it.
 

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jzichek said:
Thanks again ermeio! I believe Frank said in his article on Hyperscale that he found some problems with the plans he got through Mikesh and had to draw up some of his own; these must be it.
Yes, the material is all that he used to scratchbuild the model - I hope it will suffice for you to carve a great model.
All the best
I enjoy your blog very much
Had I only some spare time to scratchbuild those prototipes....
regards
ermeio
 

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Jemiba thanks for the explanation and the words. At that time I'm only remembered the word in spanish: "largueros" and was late to try the translator. ;)
 

blackkite

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Hi!
 

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