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Us 90Mm Aa Guns And Ap Ammo


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#41 DougRichards

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Posted 22 May 2017 - 0347 AM

18.5mm is just under 3/4 inch.  With a straight-on hit, penetration by any of these 'pop-guns' should not have been a problem, but the upper curve that was actually above the surface presented extreme angles and a small target to the incoming round.

EDIT:  I see that this is pretty much a repeat of Ken's comment. :P

2d EDIT:  Was there any penetrating hits just below the waterline, where a flatter target angle could have offset water drag?  I just remembered posts that discussed that the Japanese had developed shells that could be effective through water.

 

That is what 3" AP rockets were for.

 

wiki

 

Anti-submarine

Soon after some encouraging results from the initial deployment, trials of the weapon were conducted against targets representing U-boats. It was discovered that if the rockets were fired at a shallow angle, near misses resulted in the rockets curving upwards in seawater and piercing the targets below the waterline. Soon Coastal Command and the Royal Navy's Fleet Air Arm aircraft were using the rockets extensively.

The first U-Boat destroyed with the assistance of a rocket attack was U-752 (Kapitän-Leutnant Schroeter), on 23 May 1943, by a Swordfish of 819 NAS. The rockets used on this occasion had solid, cast-iron heads and were known as Rocket Spears.[8] One of these punched right through the submarine's pressure hull and rendered it incapable of diving; the U–boat was scuttled by its crew. On 28 May 1943, a 608 Squadron Hudson destroyed a U-boat in the Mediterranean, the first destroyed solely by rocket.[3] These rockets were, among other factors, credited with making it too dangerous for the Germans to continue operating their Flak U-Boats, which were initially designed with heavy anti-aircraft weaponry to hold off air attacks.

From then until the end of the Second World War in Europe, Coastal Command and the Fleet Air Arm used the rockets as one of their primary weapons (alongside torpedoes, which, to a certain extent they replaced) against shipping and surfaced U-Boats.


Edited by DougRichards, 22 May 2017 - 1631 PM.


#42 shep854

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Posted 22 May 2017 - 0757 AM

Ken Estes, thanks; that was the discussion I was thinking of.  It's still hard to imagine bullets (even measured in inches) being effective through water.

----

DougRichards, that's really interesting.  Always things to learn! :)  



#43 Ken Estes

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Posted 22 May 2017 - 0812 AM

Shep, this is the work of Nathan Okun on these "Type 91" projectiles, which I see were not limited to BB main guns but also 8" [apparently one hit USS Boise at Cape Esperance] and some lighter 15cm guns.

 

http://www.navweaps....ectile_Data.pdf

 

http://www.navweaps....ch/tech-041.htm



#44 shep854

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Posted 22 May 2017 - 0814 AM

Shep, this is the work of Nathan Okun on these "Type 91" projectiles, which I see were not limited to BB main guns but also 8" [apparently one hit USS Boise at Cape Esperance] and some lighter 15cm guns.

 

http://www.navweaps....ectile_Data.pdf

 

http://www.navweaps....ch/tech-041.htm

Tanks! :)



#45 DougRichards

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Posted 22 May 2017 - 2055 PM

Ken Estes, thanks; that was the discussion I was thinking of.  It's still hard to imagine bullets (even measured in inches) being effective through water.

----

DougRichards, that's really interesting.  Always things to learn! :)

 

Which also leads into: that even though the RN had experimented with unrotated projectiles (ie rockets) from around the late 1930s, and later developments went to war as the 'Land Matress', it appears that there was no naval adoption of a mounting able to fire 3in rockets against aquatic targets, particularly surfaced submarines.

 

The RN of course used rockets on adapted landing craft for shore bombardment.



#46 Chris Werb

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Posted 19 June 2017 - 0430 AM

Late in WW2 we fielded a 4" underwater attack projectile for breech loading guns called "Shark"

 

http://ww2talk.com/i...ojectile.55368/



#47 ickysdad

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Posted 12 July 2017 - 0113 AM

Shep, the IJN developed below water projos, but only for large caliber guns, intending to get under the main belt and into the lighter defense array of BBs. They never had an opportunity to try them.

 Yamato may have hit White Plains with a diving type projectile.....

 

 http://warships1disc...=1#.WWW9xYWcEdU



#48 Ken Estes

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Posted 12 July 2017 - 0741 AM

More likely the mining effect of a near miss. A major caliber hit by a diving projectile would have caused very heavy damage, likely sinking a CVE if it exploded. See pp. 117-19.

 

http://www.damagecon...other CVE's.pdf



#49 ickysdad

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Posted 12 July 2017 - 1037 AM

More likely the mining effect of a near miss. A major caliber hit by a diving projectile would have caused very heavy damage, likely sinking a CVE if it exploded. See pp. 117-19.

 

http://www.damagecon...other CVE's.pdf

 

More likely the mining effect of a near miss. A major caliber hit by a diving projectile would have caused very heavy damage, likely sinking a CVE if it exploded. See pp. 117-19.

 

http://www.damagecon...other CVE's.pdf

 

Do you have Rob Lundgren's book? it's a pretty good read on the issue. He used and provided a far more detailed report then the one you linked to .

 

   http://warships1disc...=1#.WWW9xYWcEdU






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