Cardonald Shells?

[marty1]

I am looking for information on British Cardonald shells. Apparently Cardonald 15" APC was superior in penetration capability to similar shells produced by other ammunition manufacturers. I am curious if anyone knows why these shells were superior?

Thanks in advance for any help.
Regards
marty

[Tiornu]

The Cardonald shell strikes me as something of an achievement. In practical terms, its superiority was in its ability to handle extreme obliquities, almost matching US shells in that regard, but retaining the larger burster typical of British shells. If you look at the FACEHARD calculations, you won't find much difference in effective penetration, but the Holing Limit is more favorable.

[marty1]

Thanks Tiornu. There are a couple of things I am hoping to look at over the next day or two, at which point I was hoping to be able to ask one or two additional questions on the subject. And yes, my question was motivated after looking over the open source code for FACEHARD. Cardonald shows up quite often in the code which prompted me to wonder what was so special about this projectile to warrent so much attention in the source code.

Best Regards
marty

[marty1]

The Cardonald shell strikes me as something of an achievement. In practical terms, its superiority was in its ability to handle extreme obliquities, almost matching US shells in that regard, but retaining the larger burster typical of British shells. If you look at the FACEHARD calculations, you won't find much difference in effective penetration, but the Holing Limit is more favorable.

Try as I might, I have been unable to find anything in my myriad of USN or RN ballistic trial reports that describes "holing limit". Is this your own term?

Regards
marty

[Ulrich Rudofsky]

Armor Penetration Definitions - The ability of an Armor Piercing projectile to penetrate armor is defined as follows:


From: http://72.14.207.104/search?q=cache:a7Y ... 3&ie=UTF-8


Partial Penetration - For hits of less than 45° obliquity, the forward half of the shell penetrates the armor while the rear half is rejected. For hits over 45° obliquity, the nose and upper body are rejected while the broken lower body penetrates.
Holing Limit - The maximum thickness of face hardened armor plate that can be damaged by a particular AP projectile. The projectile itself is rejected, but a plug of armor, usually of the diameter of the striking projectile, is pushed into the ship.
Naval Limit - The maximum thickness of armor where at least 80% of the projectile penetrates. Usually this means that the projectile is broken up and will probably not explode, but it will still inflict splinter damage on whatever is behind the armor plate.
Effective Limit - The maximum thickness of armor a projectile will penetrate relatively intact and still explode as intended.

[mike1880]

Terminology is specific to time and place. I don't think you'd find any such terminology in a British Admiralty document of WW2 or earlier, I haven't seen enough USN ones to know what they were doing. My interpretation is that although they would recognise the concepts these terms represent a convenient and not very precise shorthand; at the time they used a more precise (if less handy) descriptive schema. If you want you can equate the descriptions to the terms, for example "retrieved intact behind butt" or whatever the phrase is = same as "effective limit" (assuming - big if! - that the fuse is still in place).

As far as I'm aware, the whole furore about the Cardonald APC is based on a throwaway comment in an Admiralty report that its oblique penetration was equivalent to previous APC at ten degrees closer to normal. I stand to be corrected if there's anything more rigorous and scientific than that, but if that's all there is then it's all bricks without straw.

Mike

[marty1]

Thanks for posting the URL Ulrich -- you are an amazing search engine . As you know I am in the process of a bit of research on WWI AP projectiles. To that end I am interested in information that is traceable to specific source material. Over the years I have become a little skeptical of unreferenced information on the internet. Do you have any idea where those Misc Definitions were obtained?

For instance I have never seen US Naval Ballistic Limit defined in the manner described on the above URL before. I have typically seen it defined as the "majority" of the projectile must pass completely through the target plate. Moreover the exact proportion of passage -- i.e. the web site says 80% -- was less critical than the ability of the bursting charge to deliver a high order detonation following complete penetration. Perhaps this is a post WWII refinement, although I have a DPG memorandum on the subject of “Definition of Terminology used in Ballistic Testing” dated 1947, and there is no specific percentile attached to projectile passage.

Were the definition derived from a USN Ordnance manual? If so what is the title and year of publication?

Thanks again for your help Ulrich.
Best Regards
Marty

[marty1]

Terminology is specific to time and place. I don't think you'd find any such terminology in a British Admiralty document of WW2 or earlier, I haven't seen enough USN ones to know what they were doing. My interpretation is that although they would recognise the concepts these terms represent a convenient and not very precise shorthand; at the time they used a more precise (if less handy) descriptive schema. If you want you can equate the descriptions to the terms, for example "retrieved intact behind butt" or whatever the phrase is = same as "effective limit" (assuming - big if! - that the fuse is still in place).

As far as I'm aware, the whole furore about the Cardonald APC is based on a throwaway comment in an Admiralty report that its oblique penetration was equivalent to previous APC at ten degrees closer to normal. I stand to be corrected if there's anything more rigorous and scientific than that, but if that's all there is then it's all bricks without straw.

Mike

Hi Mike:

I agree. I have a fair amount of ADM material on ballsitic testing spanning from pre-WWI to post WWII. My Dahlgren material is mostly pre-WWII (1930's), WWII and post WWII. Definition of terminolgy used in terminal ballistics change subtly over the years.

I havent seen the "holing limit" term before, but am always willing to learn . It sounds from the definition provided on the above URL that holing limit was very similar to the more modern "Protection Limit". I want to make sure I understand what the subtle advantages provided by Cardonald produced shells were supposed to be.

Regards
marty

[Ulrich Rudofsky]

It may be that Nathan Okun coined the term of HL and HBL: " I call the velocity that allows a hole to be punched through the plate of roughly caliber size or greater, whether the projectile itself penetrates or not, the "Holing Ballistic Limit" (HBL) and it is very important to impacts against brittle face-hardened armor, where the armor material that used to be in the hole is punched out the plate back at high speed and acts as a second, rather large, solid shot projectile (intact or in pieces), or in homogeneous, ductile armor at high obliquity when the projectile breaks or it explodes prior to bouncing off (especially at very high obliquity where the canoe-shaped gouge and tear in the plate may be quite long and the base fuze delay short enough to explode the projectile before the projectile has moved far enough from the initial impact point to begin to be deflected away from the plate face). The sometimes even lower striking velocity that begins to crack the plate open entirely through from face surface to back surface is termed the "through crack" or, in the U.S. through the end of WWII, the "Army Ballistic Limit" (ABL)--for face-hardened armor, the ABL and HBL are virtually the same (all or nothing effect), but the ABL may be far lower than the HBL at high obliquity against homogeneous, ductile armor where a hair-line slot may be torn in the plate during ricochet that satisfies the definition of the ABL but has virtually no effect on decreasing the protection afforded by the plate against that impact. At low obliquity against homogeneous, ductile armor hit by a pointed-nose projectile, the ABL may also be much lower than the HBL--the NBL and HBL are usually quite close to one-another--but the heavy projectile nose plugs the hole and prevents any explosive effects from passing through the small hole in the plate when the plate is hit at between the ABL and HBL, so the ABL may have little meaning. If the projectile has a flat or at least very blunt nose, however, it may cut out a disk-shaped plug at the ABL in homogeneous, ductile armor that can cause some damage behind the armor even if the projectile does not penetrate itself--here, as in face-hardened armor, the ABL and the HBL are the same.
http://www.combinedfleet.com/miscarmor.htm

[marty1]

Hi Ulrich:

I think you’re onto something with that last post. It would certainly explain why I can’t seem to find this terminology in DPG testing reports and memoranda. A useful term if I understand it correctly -- particularly for confined areas. It's unclear how a particular projectile --Cardonald Produced Shells that is -- would be more inclined to cause back-surface spalling than another projectile of the same basic shape. This would seem to be more of an armor quality issue.

I guess I took Tironu's original comment to be that the Cardonald produced projectiles were more resistant to bending stress indicative of oblique penetration -- i.e. Cardonald's are less inclined to break-up in oblique penetration. Instead -- they seem to be more efficient at generating back-spall from non-penetrating hits than other manufacturer’s versions of the same projectile?

Thanks again for your efforts.

Best Regards
marty