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Anti-Submarine Shells

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I'm aware that the Japanese 12.7 cm/40 (5") Type 89 guns were equipped with ASW shells due to Navweaps.  However, information is sparse about how they work how effective they were.  Does anyone have knowledge about how these ASW artillery rounds worked?  Or know what they even looked like?

Projectile Types and Weights

Common Type 0 HE 1a: 51.7 lbs. (23.45 kg)
Common Type 3 IS 2a: 50.7 lbs. (23.0 kg)
ASW 3a: 46.2 lbs. (20.9 kg)
Illum 4a: 51.7 lbs. (23.45 kg)

^The flat-nosed ASW projectile was issued in 1943 following extensive testing. This is listed in US Naval Technical Mission to Japan report O-19 as being able to penetrate a 9.85 in (25 cm) plate of Ducol Steel (roughly equivalent to USN HTS) at a depth of 26 feet (8 meters). Range for this performance is not given. However, based upon other errors in this document, I would believe this to be an error in metric to english unit conversion and that the actual performance would more likely be 0.985 in (2.5 cm). ASW may have been issued only to escorts. - http://www.navweaps.com/Weapons/WNJAP_5-40_t89.php#ammonote3

 

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I have never heard of these munitions.  I've even played IJN Fanboy's Dream "Kantai Collection," and they have never referenced such things.  They have a lot of obscure equipment items in that game and not once have they ever done an ASW round.

 

And from the limited USN submarine histories I've read, I have never heard any reference of, to include post-WWII investigations, that showed a USN sub sinking specifically to these shells.  Depth charges?  Yeah.  Air attacks?  Most definitely.  Mines?  Definitely.  ASW rounds?  Nah.

 

Because of this, like the Type 3 shells for AA use, they probably weren't good.  It's not like there weren't much submarines for the IJN to go after.  If anything, there was an increasing overabundance of American submarines plaguing the Japanese.

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In-game guns can already damage submarines at 8 meters. No need for special ammunition for that, unless you want them to remove the ability of current in-game ammunitions to be able to hit submarines at 8m depth.

Edited by Lert
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I can't imagine the Japanese shells were particularly effective. Landing a direct hit on a submerged target seems pretty unlikely, and by late war US submarines were operating very effectively and taking very few losses.

My count is that 22 US submarines were sunk by IJN DD (likely to be equipped with the 12.7cm gun) and other surface ships (variably likely to have that weapon - some Kaibokan did, other ships not so much).

image.png.cb91de02a5d622f9c2b4583d2cab41de.png

Of those Argonaut was blown to the surface and shelled, but most were depth charged or engaged with traditional gunfire.

 

The British rolled out an anti-submarine shell too, but primarily designed to deal with surfaced submarines, I doubt it achieved much if anything in service -

It was – is – not easy to sink a surfaced submarine even if it was disabled. Only a small arc of the circularpressure hull would be exposed to gunfire, and the impact of a shell would be at such an oblique angle that it would glance off the tough plating without penetration. In the early years of the war, ramming was seen as a more certain kill. A study in May 1943 showed that of twenty-seven rammings, twenty-four led to the submarine’s sinking. In roughly half the cases considered, the submarine had been severely damaged by depth charges. Ramming an undamaged submarine was not easy, as the turning circle of a U-boat was less than that of most escorts (see chapter 8, table 8.10). Accounts describe a number of unsuccessful attempts to ram but overall figures are not available.

SHARK

The problem of sinking surfaced U-boats was appreciated and a special projectile, the Shark, was devised, to be fired from a 4in gun. The complete projectile weighed 96lb, was 73.66in long and was fired with a muzzle velocity of 500ft/ sec. It was intended to be fired at fairly short range and enter the water short of the submarine. Spoiler rings on the nose helped preserve the trajectory underwater. There was a hardened-steel nose (33lb), which would pierce both ballast tanks and pressure hull before the charge of 24lb of Torpex exploded. In Operation ‘Deadlight’ six Sharks were fired against U-3514 (Type XXI) at a range of 2,400 feet. The last two hit and the submarine sank in about a minute.

David K Brown. Atlantic Escorts: Ships, Weapons & Tactics in World War II

 

 

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On 9/3/2022 at 3:47 AM, Sventex said:

I'm aware that the Japanese 12.7 cm/40 (5") Type 89 guns were equipped with ASW shells due to Navweaps.  However, information is sparse about how they work how effective they were.  Does anyone have knowledge about how these ASW artillery rounds worked?  Or know what they even looked like?

Projectile Types and Weights

Common Type 0 HE 1a: 51.7 lbs. (23.45 kg)
Common Type 3 IS 2a: 50.7 lbs. (23.0 kg)
ASW 3a: 46.2 lbs. (20.9 kg)
Illum 4a: 51.7 lbs. (23.45 kg)

^The flat-nosed ASW projectile was issued in 1943 following extensive testing. This is listed in US Naval Technical Mission to Japan report O-19 as being able to penetrate a 9.85 in (25 cm) plate of Ducol Steel (roughly equivalent to USN HTS) at a depth of 26 feet (8 meters). Range for this performance is not given. However, based upon other errors in this document, I would believe this to be an error in metric to english unit conversion and that the actual performance would more likely be 0.985 in (2.5 cm). ASW may have been issued only to escorts. - http://www.navweaps.com/Weapons/WNJAP_5-40_t89.php#ammonote3

 

http://www.navweaps.com/Weapons/WAMJAP_ASW.php

Quote

The Japanese developed anti-submarine projectiles for most naval guns between 3" (7.6 cm) and 6" (15.2 cm). These were Common Type 0 (1940) with a cylindrical head over the nose for the 6" (15.2 cm) and 5.5" (14 cm) guns and a flat-headed shell for the 5" (12.7 cm), 4.7" (12 cm) and 3" (7.6 cm) guns. These were introduced in 1943.

The larger guns had a muzzle velocity of about 820 fps (250 mps) and a range of 4,370-4,700 yards (4,000-4,300 m) at elevations of 40 degrees. The minimum range was 820-875 yards (750-800 m). The 3" (7.6 cm) projectile values were 3,500 yards (3,200 m) maximum and 765 yards (700 m) minimum.

So it was listed as Common Type 0 (1940).

Haven't found a picture and only NAVWEAPS has anything on them.

I find it odd that you can only find it on one specific web page and not anywhere else. That raises a flag or two to me.

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Someone helpfully messaged me the documentation on the Anti-Submarine Shells from the Declassified documents of the US Naval Technical Mission to Japan:

Anti-Submarine Projectiles: These projectiles appear to be the type showing the greatest originality in design.   It is difficult to obtain any true picture of their effectiveness during the war.

Part III Anti-Submarine Projectiles

Considerable effort was directed by the Japanese Navy to develop projectiles which would continue an undisturbed trajectory after striking the water.

The Japanese did not devote much thought to the development of long projectiles for this purpose, but decided as the result of experiment that a flat-nosed projectile in which the area of the flat front was equal to half the area of the base that was most efficient.  These were adopted after extensive tests in 1943.  The first type, shown in Diagram A of Figure 6 was an adaption of the HE common projectile, onto the shoulder of which a water penetrating cap was screwed.

789025639_Anti-SubmarineProjectile.thumb.jpg.342e4dbd31e3dff6484c025fec9709b1.jpg

Production was later switched to the type shown in Diagram B in Figure 6, which was designed solely as an anti-submarine shell.  Characters of the shell are given in Table VI.

Photographs of two anti-submarine projectiles are shown in the bottom left corner of Figure 7.

1454937607_Figure7.thumb.jpg.bce0aa80a2a725ad8653125b9269910c.jpg

http://www.fischer-tropsch.org/primary_docume0416 Report 0-19.pdf

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Nice find, @Sventex.  Thanks for sharing.  :-)

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