Kyushu J7W1 Shinden Armament

[Pelzig]

Greetings, all:

I've been poking through the Famous Airplanes of the World #129 on the Shinden and ran into a quandary.

For those who have it, on page 20, it shows a nose cut-away showing the four 30mm cannons but in the lower portion of the nose are two 7.92mm Type 1 machine-guns and a gun camera.

Now, a version of the Shinden for training purposes was proposed in which the cannons would be replaced with four Type 1 machine-guns.

The Shinden specs in the book list the two Type 1 weapons and this is the only source I've ever seen that even mentions those two weapons along with the standard 30mm cannon fit.

One website, if the Russian translated correctly, mentions that because the Type 5 has a relatively high rate of fire and each gun only carried 66 rounds, that the two machine-guns were used for ranging so that if the machine-gun rounds were hitting the target, the pilot could then fire the cannons with a high probability of striking successfully.

So, my main question is, what is correct for the Shinden. Were the two Type 1 machine-guns to be fitted as standard or is the illustration simply showing a proposed idea.

Cheers!

;D

 

[gral_rj]

There's a cut-away drawing in 'The X-Planes of the Imperial Japanese Navy & Army 1924-45' that shows exactly that, two MGs in the lower nose. Unfortunately, my Japanese isn't good enough to tell if it's a proposal or not, although I suspect it's the standard armament.

 

[Pelzig]

Indeed! I have the book and noticed that as well, even the two ports for them in the front view. But then, in the same chapter, Nohara lists no machine-guns in the specs.

So, either it was an oversight or they aren't listed because they weren't meant as offensive weapons, simply a means to range the cannons.

There's a cut-away drawing in 'The X-Planes of the Imperial Japanese Navy & Army 1924-45' that shows exactly that, two MGs in the lower nose. Unfortunately, my Japanese isn't good enough to tell if it's a proposal or not, although I suspect it's the standard armament.

 

[Justo Miranda]

Feasible

 

[Pelzig]

It certainly seems to have been planned. The key questions are, was it to be standard or was it proposed. And was their purpose as ranging weapons as opposed to actual offensive weapons?

Find below scans showing the placement and one front view showing the gun camera and the two MG ports.

The first two are from FAotW #129 and the other from the Green Arrow book on IJA/IJN x-planes.

Feasible

 

[Justo Miranda]

I do agree...

 

[blackkite]

Hi! According to Japanese text of the drawing, 7.9mm machine gun was for training.

 

[gral_rj]

Hi! According to Japanese text of the drawing, 7.9mm machine gun was for training.

You mean, in the second drawing of Pelzig's last post? I see it now.

 

[Pelzig]

So, basically, the two Type 1 were fitted simply for use during training only? One source says that a proposal for the Shinden was to remove the 30mm cannons and in their place were four Type 1s.

Was the Type 5 that rare and the ammunition that precious? It also seems odd that the plane would carry what was, essentially, dead weight if the machine-guns had no offensive purpose. Or, were they installed for training and removed on combat aircraft?

At a rate of fire of 500 rounds per minute and with only 66 rounds per gun, that is about 8-9 seconds of sustained fire per gun if my math is any good. Not much at all. So, the idea of the Type 1s being used for ranging and targeting (which some tanks did in WW2 before laser range sights showed up) has a kernel of validity to it. The pilot fires the machine-guns, the rounds strike the target, he can then tap the cannon trigger with a reasonable assurance of a hit with the 30mm cannons of which one or two shells would be enough to damage or even down a aircraft.

Hi! According to Japanese text of the drawing, 7.9mm machine gun was for training.

 

[hole in the ground]

by training... is that a litteral translation? could it mean training as in gun laying? or is it deffinitely training as in teaching?

 

[Pelzig]

The first kanji in the second of three scans I posted does mean "lesson" or "teach". The third kanji, prior to the 7.9mm can translate as "use" or "for". The second kanji can translate as "train". I checked for other translations that might hint as gun laying but found none.

So, I guess that brings up a new set of questions. Were the machine-guns fitted as standard or only installed during training? Some cut-aways of the Shinden either show them or don't. If they were fitted for training, that kind of nullifies the concept of replacing the cannons with four of the Type 1 weapons as one source mentioned.

To me, at least, you have cannons installed. Why not train with those? What was the real need for the two machine-guns?

I'm partial to the gun laying theory but the kanji isn't bearing that out.

Cheers!

by training... is that a litteral translation? could it mean training as in gun laying? or is it deffinitely training as in teaching?

 

[blackkite]

Hi! Shinden（震電）'s object was to intercept B-29s. 7.9mm machine gun had no meaning for B-29.
It was very difficult to shot down B-17 evev ｂｙ Zero(零戦）'s 20mm cannon!

 

[Jemiba]

"7.9mm machine gun had no meaning for B-29"

That's correct, but due to the small amount of ammo for the 30mm
guns, which would have resulted in quite a short burst, the 7,9mm
culd have been used to help aiming. That was a usual method
during those times. IIRC, the 12,7mm of the B-25 with 75mm guns
were mainly used for gun laying, too.