The Na-To

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Luftflotte2
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The Na-To

Post by Luftflotte2 » 02 Oct 2010 22:54

About The Na-To

In 1943 the decision was made to develop a tank gun based on the type 4 75 mm aa-gun which became operational in early 1944.
For this gun a special gun carrier should also be developed, based on the chassis of a newly designed full-tracked heavy transport vehicle (Chi-So) using a remodelled chassis of the type 4 experimental tank Chi-To.
A prototype was built in April, 1944. The engine of this vehicle was placed in the bow. The engine room and the driver cabin for the driver and the wireless operator were armoured with welded 12 mm thick armour plates.
Behind the driver´s cabin the type 4 75 mm tank gun should be placed on a special pivot mount. A 12 mm gun shield should covered the 5-men gun crew from infantry ap-rounds, but only from the front. The chassis was tested in summer 1944 showing a large vulnerability of the gun crew regarding infantry fire from the sides. This was solved by installing two aditional side armour plates on both sides of the gun mount.
The gun prototype was also tested in Summer 1944 showing multiple problems with stability and recoil mechanism making a major redesign necessary. This redesign was done in early 1945. Now there were additional problems with the gun mounts of the type 4 tanks but as the guns on the Na-To were mounted on a pivot there was no problem for the use on the tank hunter.
The completed vehicles were tested in spring 1945 showing a good mobility and cross-county ability. The gun was able to penetrate the US medium M4 on ranges over 1000 m making the vehicle a dangerous weapon. In May, 1945, a couple of type 5 75 mm tank hunter Na-To were sent to northern China for battlefield tests. It is possible that these vehicles were destroyed during the soviet attack in August, 1945 but all documents egarding these late-war developments were destroyed after the japanese surrender.
That Type 5 is deadly!! It getting up to German power 8O

manufacturer: Osaka Rikugun Zoheisho (Osaka Army Arsenal)
number of vehicles built: 2 or more??
total weight: 15 t
crew: 7 men
maximum armour strength: 12 mm
length: 5800 mm
width: 2400 mm
height: 2750 mm
engine: Mitsubishi 8 cylinder gasoline engine
power: 165 hp/2000 rpm
maximum speed: 40 km/h
power-weight-ratio: 11 hp/t
armament: 1 X Typ 5 75 mm gun
armour max: 12mm


here's some pics
the first is it on tests
however, does anyone have any info or pictures of the Chi-So
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Akira Takizawa
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Re: The Na-To

Post by Akira Takizawa » 03 Oct 2010 06:14

I comment on Na-To somewhat.

Na-To was first planned as anti-tank gun. But, as it was not practical to draw it, it was revised to self-propelled gun.

Na-To gun was converted from Type 4 75mm AA gun as well as Type 5 75mm tank gun. But, they were different guns, because Na-To gun was designed as anti-tank gun. However, it was decided to use the common gun as 75mm tank gun for Na-To in early 1945. Na-To gun was redesigned and it was called Mark II (Old one was called Mark I). Na-To on above photos was mounted with Mark II.

Taki

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tom!
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Re: The Na-To

Post by tom! » 03 Oct 2010 09:09

Hi.

A drawn 75 mm at-gun. That´s interesting.

AFAIK the 57 mmm at-/tank gun project was cancelled in 1942 due to a too high weight in combination with a lack of power caused by the strict weight limitations. A 75 mm gun would have had at least the same weight.

Are there any further informations about and/or drawings of the Mark I gun?

Yours

tom! :wink:

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Akira Takizawa
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Re: The Na-To

Post by Akira Takizawa » 03 Oct 2010 09:50

Mark I
Caliber : 75 mm
Barrel Length : 4.23 m
Barrel Weight : 761 kg
EL Angle of Fire : -8 to +19 Degrees
AZ Angle of Fire : 20 Degrees each
Muzzle Velocity : 830 m/sec
Recoil Length : 1,250 mm
Recoil Reaction : 3,000 kg

Mark II
Caliber : 75 mm
Barrel Length : 4.23 m
Barrel Weight : 840 kg
EL Angle of Fire : -8 to +19 Degrees
AZ Angle of Fire : 20 Degrees each
Muzzle Velocity : 830 m/sec
Recoil Length : 400 mm
Recoil Reaction : 8,400 kg

Below is the Mark I. Compare with above photos. It has a long cradle, because the recoil lenght is long. Recoil brake and gun breech are also different.

Taki
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tom!
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Re: The Na-To

Post by tom! » 03 Oct 2010 12:34

Hi

Thanks for this infos.

I know this photo but I thought that it shows the abandoned first prototype of the Type 5 75 mm tank gun. Or are these guns identical?

Why was it dropped? Recoil mechanism problems?

Yours

tom! :wink:

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Akira Takizawa
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Re: The Na-To

Post by Akira Takizawa » 03 Oct 2010 15:36

> I know this photo but I thought that it shows the abandoned first prototype of the Type 5 75 mm tank gun. Or are these guns identical?

No, 75mm tank gun is different from it. This gun was designed as anti-tank gun.

> Why was it dropped? Recoil mechanism problems?

Because it was decided to use the common gun as 75mm tank gun. The higher-level would think that it is not economical to produce two different kinds of 75mm guns.

Taki

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Luftflotte2
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Re: The Na-To

Post by Luftflotte2 » 03 Oct 2010 15:45

Thanks, always interesting stuff Taki.

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Re: The Na-To

Post by Luftflotte2 » 04 Oct 2010 01:25

However does anyone have any info or pictures of the Chi-So APC.

Thanks

another Na-To
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Akira Takizawa
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Re: The Na-To

Post by Akira Takizawa » 04 Oct 2010 02:12

Luftflotte2 wrote:However does anyone have any info or pictures of the Chi-So APC.

I have never seen any info or picture of Chi-So. I believe that they don't exist.

Taki

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Luftflotte2
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Re: The Na-To

Post by Luftflotte2 » 04 Oct 2010 02:20

I think I've seen a picture of it but that's about it. I'm trying to find it.

Found It
or maybe its just the Na-To without the gun???
I think there was an actual Type 4 (1944) Chi-So, it looks designed to an APC. Maybe the prototypes of this vehicles were converted to Na-To s.

It makes me angry to know that the US destroyed most of Japan's military documents and equipment after the war. This info maybe lost forever :x :x
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Akira Takizawa
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Re: The Na-To

Post by Akira Takizawa » 04 Oct 2010 02:48

Luftflotte2 wrote:Found It
or maybe its just the Na-To without the gun???

It is not Chi-So, but Na-To. Chi-So is a tracked truck. So, it had a loading platform. I upload a drawing of Chi-So.

Taki
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Last edited by Akira Takizawa on 04 Oct 2010 03:00, edited 2 times in total.

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Luftflotte2
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Re: The Na-To

Post by Luftflotte2 » 04 Oct 2010 02:56

Ok, what about this......your picture of the Chi-So could be its original design. That design was later changed to my picture above. That 'changed' model could be the original design of the Na-To which towed the 75mm gun(as you said earlier). Now......that first Na-To was not very good, so they mounted the 75mm on the Chassis which became the Na-To in my original post

could we have a larger picture please, :)
Thanks again

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Akira Takizawa
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Re: The Na-To

Post by Akira Takizawa » 04 Oct 2010 05:17

I upload a large picture. This board has a limitation of uploading image size. So, I load it vartically.

Taki
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Luftflotte2
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Re: The Na-To

Post by Luftflotte2 » 13 Nov 2010 23:56

Here is some other photos of the Type 5 Na-To
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Re: The Na-To

Post by Luftflotte2 » 13 Nov 2010 23:57

one more of the gun on trials.
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