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#21 shep854

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Posted 19 May 2017 - 1809 PM

Re: Destroyer escorts

In 1940/41 German aircraft sank a lot of ships in waters near and sometimes not that near the UK. Thus DE needed some kind of heavy AA gun. At first nothing but the old 3" was available and I'm fairly sure they weren't even having FCS. The guns were also not able to reliably penetrate U boat hulls.

Still, better than a pom-pom or 40mm



#22 DougRichards

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Posted 19 May 2017 - 1948 PM

I was under the impression that 3" on early DE classes was because they weren't considered 'front line' vessels, 5" was prioritized for the first-line ships and 3" was 'good enough' against subs?  Could the 3"/50 penetrate a sub's pressure hull?  I've read many statements that the RN 4"/40 that armed their light escorts couldn't.

 

I cannot find the reference, but I seem to remember that RN Hunt Class DE were equipped with two or three torpedo tubes, but for fleet work, but for dealing with U boats that had been forced to the surface.  I would assume that USN DE had their triple torpedo tubes for a similar reason, as I cannot imagine too many situations where 22kt ships would be expected to throw themselves into a fleet torpedo action.


Edited by DougRichards, 19 May 2017 - 1948 PM.


#23 shep854

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Posted 19 May 2017 - 2004 PM

 

I was under the impression that 3" on early DE classes was because they weren't considered 'front line' vessels, 5" was prioritized for the first-line ships and 3" was 'good enough' against subs?  Could the 3"/50 penetrate a sub's pressure hull?  I've read many statements that the RN 4"/40 that armed their light escorts couldn't.

 

I cannot find the reference, but I seem to remember that RN Hunt Class DE were equipped with two or three torpedo tubes, but for fleet work, but for dealing with U boats that had been forced to the surface.  I would assume that USN DE had their triple torpedo tubes for a similar reason, as I cannot imagine too many situations where 22kt ships would be expected to throw themselves into a fleet torpedo action.

 

A quick Wiki search indicated that Edsall and Rudderow classes were built with the triple torpedo mounts.  Torpedo tubes on convoy escorts does seem redundant, but they were put to good use off Samar.  :mellow:


Edited by shep854, 19 May 2017 - 2013 PM.


#24 Ken Estes

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Posted 20 May 2017 - 0055 AM

Convoys had to deal with surface raiders on more than one occasion in WWII. One never knew when smaller DD types might have to take on more capable warships. the similar IJN Matsu class escort ships carried four 24 in. long lance torpedoes in a single four-tube mount for that reason. DEs and RN sloops etc were also escorts for CVEs in H/K ASW TFs. There were occasions to try and torpedo a surfaced submarine but I don't think it ever worked, particularly against the agile type VII series U-boats.

 

Most ship designs of WWII had been worked out before the US Army put the 90mm M1 into production, not that there was much interservice liaison and cooperation in any case. USN 3"/50 had a capable AP round, filled with explosive in the 1930s and given the army M66A1 base fuze. The HC ammunition also had some AP characteristics, esp. when the PD fuze is set to delay. 

 

All rounds for the gun were 5.9kg, with MV of 823 m/s [2700 fps] so penetration would be superior to US Army 3-inch ammo; Rich has some details on this, maybe with penetration figures, which might be found in Campbell, Naval Weapons of WWII.

 

WNUS_3-50_mk10-22_cutaway_pic.jpg


Edited by Ken Estes, 20 May 2017 - 0102 AM.


#25 Stuart Galbraith

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Posted 20 May 2017 - 0252 AM

Re: Destroyer escorts

In 1940/41 German aircraft sank a lot of ships in waters near and sometimes not that near the UK. Thus DE needed some kind of heavy AA gun. At first nothing but the old 3" was available and I'm fairly sure they weren't even having FCS. The guns were also not able to reliably penetrate U boat hulls.

I read a biography by an RN ASW group commander some years ago, and Im sure I recall him saying the 3 incher they had only had solid shot, and were horrified to see it bound off the pressure hull of a surfaced German submarine.

 

Though they probably ran it over in short order, so I guess its something of a moot point....



#26 shep854

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Posted 20 May 2017 - 0826 AM

 

Re: Destroyer escorts

In 1940/41 German aircraft sank a lot of ships in waters near and sometimes not that near the UK. Thus DE needed some kind of heavy AA gun. At first nothing but the old 3" was available and I'm fairly sure they weren't even having FCS. The guns were also not able to reliably penetrate U boat hulls.

I read a biography by an RN ASW group commander some years ago, and Im sure I recall him saying the 3 incher they had only had solid shot, and were horrified to see it bound off the pressure hull of a surfaced German submarine.

 

Though they probably ran it over in short order, so I guess its something of a moot point....

 

I've read more than one statement attributed to RN members that referred to the 4"/40 as a 'popgun'.



#27 shep854

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Posted 20 May 2017 - 0827 AM

Convoys had to deal with surface raiders on more than one occasion in WWII. One never knew when smaller DD types might have to take on more capable warships. the similar IJN Matsu class escort ships carried four 24 in. long lance torpedoes in a single four-tube mount for that reason. DEs and RN sloops etc were also escorts for CVEs in H/K ASW TFs. There were occasions to try and torpedo a surfaced submarine but I don't think it ever worked, particularly against the agile type VII series U-boats.

 

Most ship designs of WWII had been worked out before the US Army put the 90mm M1 into production, not that there was much interservice liaison and cooperation in any case. USN 3"/50 had a capable AP round, filled with explosive in the 1930s and given the army M66A1 base fuze. The HC ammunition also had some AP characteristics, esp. when the PD fuze is set to delay. 

 

All rounds for the gun were 5.9kg, with MV of 823 m/s [2700 fps] so penetration would be superior to US Army 3-inch ammo; Rich has some details on this, maybe with penetration figures, which might be found in Campbell, Naval Weapons of WWII.

 

WNUS_3-50_mk10-22_cutaway_pic.jpg

Thanks! The NAVWEPS site was sorely lacking in terminal performance data.



#28 Rich

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Posted 20 May 2017 - 0912 AM


All rounds for the gun were 5.9kg, with MV of 823 m/s [2700 fps] so penetration would be superior to US Army 3-inch ammo; Rich has some details on this, maybe with penetration figures, which might be found in Campbell, Naval Weapons of WWII.

 

 

 

Yes, somewhere I think I have the comparative penetration values derived from the postwar Navy tests at Dahlgren in 1947. However, the epiphany was not the penetration, it was the Navy finding the "3” M62 APC split and broke up when impacting 3” homogeneous armor plate at 30°and 60°obliquity at velocities up to 2,900 feet per second. On examination, the projectiles exhibited variable hardness with soft spots at the nose, contributing to the failures. However, Navy 3” Mark 29-2 AP projectiles did not shatter." On top of that, while the Army Ordnance did react to there own, earlier tests in 1943 to improve the hardness specifications for 90mm AP that resulted in the (too late for the war) development of the AP T33, no effort I know of was made wartime to improve the specifications for 3" M62 APC or 90mm M82 APC. Nor did it seek to solve the problem with premature firing of its BDF found in the Showburyness tests of May 1944. Instead, Army Ordnance went with HVAP as the solution and ignored its problems.



#29 Ozarks

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Posted 20 May 2017 - 1318 PM

Proximity fuzes could also be used against ground forces.



#30 shep854

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Posted 20 May 2017 - 2146 PM

Proximity fuzes could also be used against ground forces.

Yep!



#31 Ken Estes

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Posted 21 May 2017 - 0225 AM

 

Re: Destroyer escorts

In 1940/41 German aircraft sank a lot of ships in waters near and sometimes not that near the UK. Thus DE needed some kind of heavy AA gun. At first nothing but the old 3" was available and I'm fairly sure they weren't even having FCS. The guns were also not able to reliably penetrate U boat hulls.

I read a biography by an RN ASW group commander some years ago, and Im sure I recall him saying the 3 incher they had only had solid shot, and were horrified to see it bound off the pressure hull of a surfaced German submarine.

 

Though they probably ran it over in short order, so I guess its something of a moot point....

 

When you think of the pressure hull, imagine a cylinder with only a small part of the upper curve above water when surfaced. A ricochet is very likely unless one hits at the base of the conning tower. 

 

Type VIIC plating was 18.5 mm.

 

SRH009-p58.jpg


Edited by Ken Estes, 21 May 2017 - 0233 AM.


#32 Stuart Galbraith

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Posted 21 May 2017 - 0257 AM

 

 

Re: Destroyer escorts

In 1940/41 German aircraft sank a lot of ships in waters near and sometimes not that near the UK. Thus DE needed some kind of heavy AA gun. At first nothing but the old 3" was available and I'm fairly sure they weren't even having FCS. The guns were also not able to reliably penetrate U boat hulls.

I read a biography by an RN ASW group commander some years ago, and Im sure I recall him saying the 3 incher they had only had solid shot, and were horrified to see it bound off the pressure hull of a surfaced German submarine.

 

Though they probably ran it over in short order, so I guess its something of a moot point....

 

When you think of the pressure hull, imagine a cylinder with only a small part of the upper curve above water when surfaced. A ricochet is very likely unless one hits at the base of the conning tower. 

 

Type VIIC plating was 18.5 mm.

 

SRH009-p58.jpg

 

 

Yep.

 

Makes you wonder if they ever considered a light AT Gun for warships. I know the 57mm when fitted to Mosquito was a pretty good can opener.



#33 DougRichards

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Posted 21 May 2017 - 0348 AM

 

 

 

Re: Destroyer escorts

In 1940/41 German aircraft sank a lot of ships in waters near and sometimes not that near the UK. Thus DE needed some kind of heavy AA gun. At first nothing but the old 3" was available and I'm fairly sure they weren't even having FCS. The guns were also not able to reliably penetrate U boat hulls.

I read a biography by an RN ASW group commander some years ago, and Im sure I recall him saying the 3 incher they had only had solid shot, and were horrified to see it bound off the pressure hull of a surfaced German submarine.

 

Though they probably ran it over in short order, so I guess its something of a moot point....

 

When you think of the pressure hull, imagine a cylinder with only a small part of the upper curve above water when surfaced. A ricochet is very likely unless one hits at the base of the conning tower. 

 

Type VIIC plating was 18.5 mm.

 

SRH009-p58.jpg

 

 

Yep.

 

Makes you wonder if they ever considered a light AT Gun for warships. I know the 57mm when fitted to Mosquito was a pretty good can opener.

 

 

You mean

 

http://www.navweaps....pounder_m2a.php

 

But HE rounds only were carried by MGB:  which again raises the question of HE rounds being available for 6pdr AT and tank guns!



#34 Markus Becker

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Posted 21 May 2017 - 0700 AM

When you think of the pressure hull, imagine a cylinder with only a small part of the upper curve above water when surfaced. A ricochet is very likely unless one hits at the base of the conning tower. 
 
Type VIIC plating was 18.5 mm.


And in the center section you have the saddle tanks sitting outside the pressure hull.

https://goo.gl/images/SSsybD

Shell hits, penetrates but starts to veer off course and bounces off the hull?

#35 shep854

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Posted 21 May 2017 - 0801 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.


Edited by shep854, 21 May 2017 - 0809 AM.


#36 bojan

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Posted 21 May 2017 - 0833 AM

You mean

 

http://www.navweaps....pounder_m2a.php

 

But HE rounds only were carried by MGB:  which again raises the question of HE rounds being available for 6pdr AT and tank guns!

 

 

They were, they were shipped to Yugoslavian 1st Armored Brigade for use with AEC II armored cars, 60% of ammo shipped was HE (35% AP, 5% APDS).

So, they definitely became available at some moment. Long time ago, Gerry Chester (who had excellent site, now defunct http://www.northirishhorse.org/), noted that Churchills got HE for Italy campaign.



#37 Marek Tucan

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Posted 21 May 2017 - 1322 PM

Soviets mated the 57mm frag to 6pdr case, right?

 

Did they do anything for the 2pdr?



#38 bojan

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Posted 21 May 2017 - 1623 PM

They did, but then British deliveries of 6pdr HE started so project newer advanced to real production (there was some production but low level compared to other types of ammo).

For 2pdr they developed the HE rounds, one based on 37mm AA gun HE, with very wide driving bands and it was not accepted other using 40mm Bofors HE. Neither was accepted.



#39 Ken Estes

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Posted 22 May 2017 - 0029 AM

That Molins gear looks very bulky and clunky in operation for the navalized 6-pdr. The autoloader for the 3"/50 that came later [prototyped Sept45] was much better.

 

 

The saddle tanks on a submarine are free-flooding and I doubt they would even set off a base detonating fuze. These boats are really low in the water and not at all easy shots from a wet gun mount on a DE or smaller vessel:

 

350px-U995_2004_1.jpg  Out of water

 

u218.jpg U-218 under attack.

In presence of the enemy they ballasted down quite a bit. This is a view from an attacking aircraft. Imagine what it looked like from a spray-swept gun mount.


Edited by Ken Estes, 22 May 2017 - 0032 AM.


#40 Ken Estes

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Posted 22 May 2017 - 0155 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.






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