how many splinters from an AP shell/shot

[Mobius]

It is also more difficult to detonate (I assume more difficult relative to Lyddite).

Every time I hear that word I think of Luddite. They were volatile too.

[jwduquette1]

Every time I hear that word I think of Luddite. They were volatile too.

 

The thing I find rather odd, is that various British ammunition handbooks of the period specifically indicate Lyddite (or Picric Acid) as being a poor choice for bursting charges in armor piercing projectiles.

[DB]

The thing I find rather odd, is that various British ammunition handbooks of the period specifically indicate Lyddite (or Picric Acid) as being a poor choice for bursting charges in armor piercing projectiles.

Dunno about the period, but the 1915 Gunnery Manual (naval, obviously) indicates that Lyddite APC would be less effective than common and/or powder filled shell when faced with a thin plate over the main armour. Either the Lyddite was more sensitive and could premature, or the problems were with HC shells starting to break up on the thin plate.

 

Entering the realms of rampant speculation here: perhaps Lyddite got a reputation for over-sensitivity from this earlier data?

 

On a serendipitous and utterly off-topic note: your post had me reaching for Brown's "Grand Fleet", wherein I found, acting as a bookmarker, my long-lost nail file. I thank you

 

David

[Przezdzieblo]

AFAIR Brown mentioned over-sensivity reputation of Lyddite filled shells (reason for a little od configuration of warship construction with propelant charges magazine over - so, more in danger - shell magazine) AND fact that those shells give high amount of relatively small - and light - splinters, probably less effective in making a mess inside hulls and turrets.

OTOH no idea if in case of AP round, with thick walls and small amount of Lyddite inside, splinters would be small.

[jwduquette1]

On a serendipitous and utterly off-topic note: your post had me reaching for Brown's "Grand Fleet", wherein I found, acting as a bookmarker, my long-lost nail file. I thank you

 

David

 

Well I like to think I'm here to help if I can.

 

I do enjoy Brown's books, and you cant beat the price. Love that era of ships and am in fact at the moment rereading Castles of Steel.

 

On the Lyddite thing -- there is a snippet in the HM books\manuals "Text Book of Ammunition" -- both the 1936 and 1944 editions. The section on explosives. Lots of folks used picric acid back in WWI. But yes, under certain circumstances it can apparently be sensitive to shock. This is from the 1944 edition, although the 1936 edition reads almost identical:

Edited November 23, 2007 by jwduquette1

[Guest bojan]

...But yes, under certain circumstances it can apparently be sensitive to shock...

 

Heavy metals or metal oxides contamination...

Edited February 20, 2007 by bojan

[jwduquette1]

Heavy metals or metal oxides contamination...

 

yes -- I think it was picrate formation that resulted in shock sensitivity.

[DB]

yes -- I think it was picrate formation that resulted in shock sensitivity.

That seems clear from disadvantage point (vi) in the text fragment you posted, which itself seems to be a reasonable expansion of point (iv) - explaining *why* they'd used a phrase as loose as "not always sufficiently insensitive".

 

David

[jwduquette1]

That seems clear from disadvantage point (vi) in the text fragment you posted, which itself seems to be a reasonable expansion of point (iv) - explaining *why* they'd used a phrase as loose as "not always sufficiently insensitive".

 

David

 

I'm not sure if I am supposed to phrase my response in the form of a question or not? Sounds like we are playing Jeopardy.

 

Most folks had apparently stopped using picric acid between the end of WWI and WWII. The French being a notable exception.

As I recall the RN had conducted extensive trials with Lyddite filled base fuzed shells following WWI (AP-HE and common) and understood the problems associated with this explosive and it’s application to armor piercing shells -- varnished cavity or not. Yet the early WWII'ish 2-pdr AP-HE seems to have used Lyddite for its bursting charge. That seems odd to me. Makes me wonder if the German UXB manual (see image I posted above of 2-pdr MkI above) has it wrong, and perhaps the 2-pdr AP-HE shell used Shellite.

 

The United States had stopped using picric acid altogether because of the various "issues" associated with this explosive. Pre-WWII AP-HE shells manufactured in the USA used Explosive-D for tank projectiles and coastal defense base fuzed projectiles. Explosive-D being ammonium picrate -- a more stable derivative of picric acid -- albeit less powerful than picric acid or TNT. Perhaps Explosive-D is similar to Shellite? And of course as I already noted above the Germans were using PETN for at least some of their base fuzed pzgr. shells.

[Mobius]

I wonder if the added 20mm spaced armor on the Panzer L, N and M worked to decap 2pdr and 6 pdr APC shot? Then the shell would break up on the face harden hull plates.

[jwduquette1]

I wonder if the added 20mm spaced armor on the Panzer L, N and M worked to decap 2pdr and 6 pdr APC shot? Then the shell would break up on the face harden hull plates.

 

Or the spaced plates added to the front of Pz Mk-IVEs. I think the spaced plates could decap 2pdr and 6pdr APC. Although I don't know whether or not that was the specific design intent -- perhaps serendipity ala schurzen and bazooka rockets. The spaced plate could also pre-detonate bursting charges for AP-HE. I was just reading a paper on this very subject a week or two ago. I'll see if I can find it again and post the results.

Edited March 6, 2007 by jwduquette1

[Mobius]

Or the spaced plates added to the front of Pz Mk-IVEs.

There doesn't look like there is much of a gap between the plates in the IVE. It looks like some places the plates or fitting are in contact.

[jwduquette1]

maybe an inch or two on the drivers side add-ons cause of the vision slit. the other add-ons look pretty snug with the stock armor. prolly a gap around the plate in front of the ball on the radio operators side.

 

what sort of spacing on MkIII applique?

 

some photos I took when I was out at Aberdeen a few years back.

 

 

Edited March 6, 2007 by jwduquette1

[jwduquette1]

here's a mkiiiL photo I borrowed from:

 

http://www.achtungpanzer.com/pz8.htm

 

 

dunno where they burrowed it from.

 

little different arrangment in the frontal add-on plate relative to the mkiv. the add-on is monolithic as opposed to the two chunks on the mkiv. not the best photo angle, but you can sort of guess at the air gap between the applique and the main armour. the front face of the applique is maybe parallel with the front face of the drivers slit build-up -- maybe a little further forward. whats the air gap? couple inches?

[Mobius]

Here's a photo to the plate mounted on an Ausf J.

Interesting it looks like this might have some spring in the fittings from a shell hit.

[jwduquette1]

Here's a photo to the plate mounted on an Ausf J.

Interesting it looks like this might have some spring in the fittings from a shell hit.

 

good picture -- looks like maybe 100mm on top and ~140mm along the bottom. it looks more like an ad-hoc arrangement than the add-on plates to the MkIIIL and MkIIIM. Was this a standard detail on the MkIIIJ "Special", or was this something put together in North Africa?

 

 

here is a better shot of my aberdeen MkIV. They used pretty heavy buttresses relative to the brackets shown in your MKIIIJ. the appliqué is closer to the main plate than your MkIIIJ image. but like the MkIIIJ add-on these are sloped a bit steeper than the main armor plate -- about 20-deg relative to about 9-deg. spacing scales to about 25mm on the top and maybe 60 to 65mm on the bottom.

 

[Mobius]

here is a better shot of my aberdeen MkIV. They used pretty heavy buttresses relative to the brackets shown in your MKIIIJ. the appliqué is closer to the main plate than your MkIIIJ image. but like the MkIIIJ add-on these are sloped a bit steeper than the main armor plate -- about 20-deg relative to about 9-deg. spacing scales to about 25mm on the top and maybe 60 to 65mm on the bottom.

At first those look like some adhoc field mod. But the buttressing belies that.

I wonder how much armor basis added track links provide?

[jwduquette1]

my wife -- the structural engineer -- says she would call the buttress on the MkIV a "gusset". she said buttress is OK, but sort of a dumb-ass way to say gusset. who knew. I mean she doesnt know panzers from shinole -- but she apparently knows what a gusset is.

[Mobius]

my wife -- the structural engineer -- says she would call the buttress on the MkIV a "gusset". she said buttress is OK, but sort of a dumb-ass way to say gusset. who knew. I mean she doesnt know panzers from shinole -- but she apparently knows what a gusset is.

The German word for it probably is 30 or more letters long.

[jwduquette1]

The report of interest is WO 185/118. 6pdr AP and 6pdr APC trials vs. the MkIII Special. 20mm MQ plate -- ~4” air gap – 50mm FHA. Angle of tilt indicated as 10-degrees. Of the six fair hits by 6-pdr APC, it was reckoned all but one had its penetration capped stripped during passage of the 20mm MQ plate. The complete through limit velocity of the array was indicated as 1967-fps.

 

Of interest is that the limit velocity for complete through for US 57mm M86 APC of an equivalent monolithic FHA plate of 70mm thickness at 10-degrees is about 1975-fps. Same projectile vs. 70mm of monolithic RHA at 10-degrees is about 2050-fps.

[Mobius]

The report of interest is WO 185/118. 6pdr AP and 6pdr APC trials vs. the MkIII Special. 20mm MQ plate -- ~4” air gap – 50mm FHA. Angle of tilt indicated as 10-degrees. Of the six fair hits by 6-pdr APC, it was reckoned all but one had its penetration capped stripped during passage of the 20mm MQ plate. The complete through limit velocity of the array was indicated as 1967-fps.

Back to Okun's decapping formula. It seems that the plate/diameter is .44 still has a 16.6% chance of keeping the cap.

[jwduquette1]

Back to Okun's decapping formula. It seems that the plate/diameter is .44 still has a 16.6% chance of keeping the cap.

 

Yeah. But I guess if it were me I would avoid doing a Lorrin and taking one piece of data and making a mountain out of it. I assume you're trying to hone one of your wargame rule sets. In this case sometimes you only have one piece of data to go off of and are therefore forced to make a mountain out of mole hill cause' there is insufficient information to do anything else. I mean we have to do this sometimes...Don't get me wrong, I'm not trying to defend Okun's findings with any of the following.

 

Just so you are better aware of the context, the British testers were surmising the cap remained intact for one of the "fair hits". It was an educated guess on their part based upon the geometry of the penetration hole through the main armor. One clean penetration hole from the shot test in question. The other perforating and non-perforating hits suggested the projectiles were shattering or breaking up between the 20mm MQ plate and the main 50mm FHA plate. However the degree of damage to the projectile -- at least for the higher velocity perforating hits -- was insufficient to keep the damaged 6-pdr APC projectiles from perforating the main plate. Shattered perforation of the main FHA plate. The lower velocity non-perforating hits were found broken up between the MQ plate and the Main plate -- with non-perforating shatter damage to the main plate.

 

But lest someone besides yourself draws the wrong conclusion from what I am saying, the spaced array on the MkIII special appears to be less effective against 6-pdr APC than an equivelent thickness of monolithic armor -- even with the decapping and shot break up effects of the spaced array. Keep in mind my comparative "complete through" limit velocities described above are for an equivelent single plate thickness at about 10-degrees. However the actual spaced array looks to be a 20mm plate @ about 20-degrees and 50mm at about 9 or 10-degrees. Moreover the LOS thickness of the spaced array is actually slightly thicker than an LOS thickness of a single 70mm plate @ 10-deg. In the case of the spaced array it is a double whammie in terms of decreased efficiency in that the amount of plate @ 20-degrees required to cover the same space as a plate at 10-degrees will be greater. The spaced array is therefore giving less ballisitic protection and is also heavier than a single plate of equivelent thickness for the same space coverage.

Edited March 7, 2007 by jwduquette1

[jwduquette1]

for giggles have you tried running an estimate for 6-pdr APC vs. 70mm of RHA or FHA @ 10-deg using NAaB. The low obliquity is such that we shouldn't see any real masking issues as a result of Okun's weirdo slope effects model.

 

=======================================

----never mind --- just tried it and I see there is a default lower caliber limit for NAaB of 2.75" diameter APC

Edited March 7, 2007 by jwduquette1

[Mobius]

Yeah. But I guess if it were me I would avoid doing a Lorrin and taking one piece of data and making a mountain out of it. I assume you're trying to hone one of your wargame rule sets. In this case sometimes you only have one piece of data to go off of and are therefore forced to make a mountain out of mole hill cause' there is insufficient information to do anything else. I mean we have to do this sometimes...Don't get me wrong, I'm not trying to defend Okun's findings with any of the following.

Yes, I'm looking to add decapped values along side capped values for the penetration of shells. Then some die roll to see if to use the capped or decapped values. Even that might be too complicated for a miniatures game. Doable if it ever becomes a computer game.

 

I don't want to have to do any calculations of T/D vs D or whatever.