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Apr 21 17 2:21 PM
ther are several problems involved
the formulas may appaer accurate as they deliver results in tenths of any unit.
Older rangtables or drawings may also show "pseudo" preciseness.
Many german rangetables deliver inputdata and results on millimeter-paper with line thicknesses equivalent to 5-10 metres(per second) drawed with a Standard(fixed sqrt) curveline lineal. So any of the input data is best case approximative and the same is valid for the output data.
much data in printed rangetables was interpolated from approximative surveys of trajectories.
If they used a numerical solution and the intervals of calculation were comparatively wide - the result may differ considerable from a calculation with the same mathematical model with same constants but smaller intervals.
I had the impression if you can reproduce a rangetable with a new calculated solution within 5-10m/s compared to the original rangetable you can use the calculated one. This is even possible without any "Mach based" dragfunction.
I have seen ballistic models (mostly for small arms) wich omitted the vertical speed component for calculation of deceleration of the projectile.
influence of stability and obedience (hope this is the correct translation for "Folgsamkeit") of rotatet projectiles change with density of air
(orientation of the longitudinal projectile axis to the Tangent of the actual trajectory point).
with the result
under(over)spun projectiles may have different trajectories compared to the "normal" one. And they may additionally differ depending on angle of departure.
Apr 21 17 5:20 PM
Apr 21 17 7:07 PM
Apr 22 17 2:55 AM
bill jurens wrote:I'm delighted to see that several correspondents are interested in working on this problem and moving the exterior ballistic solutions forward. If I can provide any additional assistance, please let me know. One should start with a good basic program, and extend forward from there, to the limit of one's ability and/or interest. The BASIC code and the information in my paper will get you started. If copies are required, please let me know, and I can send them via e-mail.
Apr 22 17 3:34 AM
May 11 17 3:00 AM
#639…According to primary British
source 1.5" outer plate will not decap nor change path of the Green Boy
shell at 60 degree oblique impact. No decapping no change of path. So why never
18" should be decapped? And why in lower oblique? That decapping of Iowa's
belt is a myth. Possibly it could decap US shells as the only need they had in
attach head was that head will not detach during firing from muzzle. Even if
head will detach during storage was not reason for throwing avay lot of shells.
Yes WWII era shells. Not everyone made such a poor connection between cap and
rest. And more even I cap was detached but not fully destroyed will work
I. US WWII
US Navy mid-WWII 6" Mk 35
MOD 5 AP projectiles with moderately-hard AP caps (mid-500s BHN on their face
and most of their thickness, softening to circa-225 BHN in the region in
contact with the projectile nose, held on by low-temperature solder AND
crimping around the edge of the cap into a ring of shallow pits in the
projectile nose, this "double-grip" method following closely to British
post-WWI design practice) were tested at MANY penetrating velocities (near the
NBL and far above it) and obliquities up to 70 degrees. The cutoff
between no effect and decapped was extremely clean at 0.0805-caliber of any
plate (MS, STS, or HTS, it did not matter which) in this test. Only one
test had the projectile decapped at exactly 0.08-caliber plate thickness, all
other impacts against a plate of this identical thickness remained capped at
all times. This is why I added the final "05" to the required
thickness, so emphasize this sharp boundary. NOTE: One test against
a 1.5" cemented face-hardened plate (similar to that armor used in US Army
armored cars, for example, being essentially a Cr-Ni-steel version of 1891
naval Harvey armor) knocked the cap off, but otherwise did not damage it or the
projectile, indicating that such thin brittle material was useless against
capped shells that overmatched the plate by such a large amount.
In this test series, US Army
37mm M51 APC and 75mm M61 APC and 76mm M62 APC shells were also tested.
The 37mm and some of the 75/76mm projectiles required TWICE the thickness to
decap so I use 0.1605-caliber for them. From discussions of Krupp APC
projectiles (see below), it seems that some of the several manufacturers of these
projectiles in WWII were using a high-temperature, much stronger solder to hold
the projectile caps on (no crimping in Army APC shot/shells). This
exceeded the specs, which allowed low-temperature solder as used with all Navy
capped AP shells (never high-temperature solder), but they had been using the
high-temperature solder in their business prior to the Army projectile
contracts and just kept on doing so. This solder was not as strong as the
Krupp solder described below, but still way above minimum requirements,
US Army WWII decapping tests
with 76mm APC projectiles -- I assume M62 shells -- demonstrated that a plate
of, to quote, "1/12th-caliber thickness of steel" (0.0833-caliber)
would reliably decap the projectiles tested. It is from this that I
realized that US Army projectiles depended on who made them, since the tested
shells had probably come from a single batch made by a single manufacturer
(unknown, unfortunately) and all of them had acted exactly like US Navy AP
shells in this regard, implying the use of low-temperature solder, not that
used by the US Army M62 shells that the Navy tested for decapping, which must
have come from a different manufacturer or manufacturers (again, unknown,
though it could probably be dug up from my existing files). If the solder
used varied even by the same manufacturer, which is not impossible, such as if
that manufacturer was using several production lines at different facilities,
then even knowing the manufacturer would not help much. You would then
need to flip a coin as to what solder was being used in what shell, if it
mattered in some impact trial.
II, German Krupp WWII
A series of decapping tests
using Krupp standard WWII L/4.4 naval APC shells of up to 38cm (14.96")
showed that, typically, against the 38cm APC shells, 100mm (0.263-caliber)
plate would knock the AP cap off reliably and result in projectile shatter
against a thick face-hardened plate spaced at least 60cm (1.58-caliber) from
the decapping plate. If the space between the two plates was filled
with solid cement, the decapping plate thickness could be reduced to 75mm
(0.187-caliber) and the gap reduced considerably, though with a more than 10%
increase in the weight of the decapping plate/cement array. I split the difference
and use 0.23-caliber as the decapping cut-off point, since Krupp did not use
any in-between decapping plate thicknesses in its tests here, to my
knowledge. This much higher value is due to the use of a much stronger,
high-temperature solder by Krupp (no crimping was ever used) -- discussed in
the US Navy NavTecMisEu Report on German projectiles and in US Naval Proving
Ground examination reports and tests of German APC shells after WWII -- who
made almost all German naval APC ammo (some coast defense 40.6cm (16") APC
shells were made by another company in late-WWII with good results in tests,
but, to my knowledge, never any shipboard shells). High-temperature
solders have a problem in that they have to applied with very narrow tolerances
or the heating will damage the temper of the projectile nose that the cap is
being attached to, with increased nose damage and poorer test results in armor
trials. However, Krupp obviously knew how to do this properly and really
wanted to eliminate all of that crimping nonsense used in prior AP cap
attachment methods and also used by every other manufacturer in the late 1890s
(the British only added soldering ("sweating") to crimping when they
developed their much-improved post-Jutland hard-capped Greenboy APC shells in late
WWI, for example. NOTE: Even Krupp realized that it did not really
need a solder that strong and during late-WWII it made batches of 40.6cm L/4.4
APC shells for coast defense held on by RUBBER CEMENT, due to severe problems
obtaining scarce resources that late in WWII, which, when tested for grip
strength by the US Navy NPG after WWII, was about as strong as US Navy standard
low-temperature solder. These shells would only need 0.0805-caliber steel
plates to knock off their AP caps.
III. British WWII
During the time frame of 1945-49
the British Navy used 380-lb 9.2" Coast Defense gun APC projectiles
-- the latest WWII Mk XIIB APC shells, I assume, though I am not sure which
manufacturer, if this mattered (during WWII some were made by the US Crucible
Steel Company, for example) -- in a rather large series of decapping trials
using decapping plates of either CA (face-hardened) or NCA (homogeneous) of
0.98" (0.107-caliber), 1.47" (0.16-caliber), and 1.96"
(0.213-caliber) thickness versus CA main back plates from 5.39" to
6.37" thick all hit at 30 degrees obliquity. The gap between the
plates was usually a standard 10" (1.087-caliber) based on a mass-produced
"egg crate" framework. To compare the results, two solid CA
plates 7.84" thick were tested -- unfortunately, one of these two plates
gave rather poor results, though the other was fully within the British Navy
acceptance requirements and was used as the reference plate to score the
decapping arrays as to effectiveness. These 9.2" APC shells are
rather light in weight, their total weight being the same as used in British
pre-WWI naval guns. Amazingly enough, these APC, pound-for-pound, in
tests showed that they were the best British APC shells ever made, to my
knowledge, which is even more amazing due to the fact that, along with their
original weight, they also kept their original filler weight of 3.87% (near the
SAPC level by WWII, where all other British APC had reduced their filler
weights to only 2.5%) -- now insensitive Shellite HE filler, I believe, instead
of the original WWI too-sensitive Lyddite filler -- yet without any seeming
problem in shell breakage at oblique impact in tests compared to their larger
brother APC used in British WWII battleships.
Tests where a 1.96" CA plate
was laminated to the face of a 5.88" CA plate (no gap) was a miserable
failure, as expected, with the shells penetrating virtually undamaged in most
impacts at a rather low velocity and even the one shell that broke up did so
while completely penetrating the plate (no shell tested failed to penetrate
completely). Face-hardened armor does not stack well, it seems.
A similar test with a 1.47"
NCA plate laminated to the face of the 5.88" CA plate did not have
particularly a low resistance compared to the other, spaced, plate arrays, but
it did have the only two other tests with paired plates (as opposed to the two
solid 7.84" plates, both of which had more than one intact complete
penetration, each) where an intact complete penetration and a Stuck-in-Plate with
damaged cavity, but still in one piece, otherwise, occurred in this test
series. Thus, it was not quite up to damaging the projectile as much as
the spaced tests described below were.
All other tests used the egg
With the various spaced arrays
using different combinations of decapping plates and main back plates, the
following became evident:
(1) The strength of the
homogeneous NCA plates (two different hardnesses were used) had no noticeable
effect at all as to decapping (same as the US Navy 6" Mk 35 MOD 5
(2) The thinnest
0.98" NCA plate (no CA plate this thin was made) was quite capable of
ALWAYS decapping the projectiles, which were standard British Navy Service
designs using their regular low-temperature solder and lower edge of cap
crimping to the nose of the shell (again, as with the US tests).
(3) The thicker the main
plate, the higher the minimum striking velocity to get even a hole in the plate
was, as would obviously be expected, all else being equal.
(4) Note that these many
arrays arrays >>>DID NOT<<< increase the average required
striking velocity to penetrate compared to the best 7.84" solid
plate. In fact, the average NBL of all of these arrays was somewhat below
that of the better 7.84" solid CA plate. There most definitely needs
to be some minimum gap (Krupp found it to be about 1.6 caliber) to allow the
projectile and cap to totally separate so that the projectile's bare nose hits
the main back plate and shatters, with the resultant increase in CA plate
resistance and a net improvement in the entire array's level of
protection. As noted, though, the greater the gap, the more weight must
go into supports and such, so the total weight needed to stop the shell in many
cases is more than the weight gained by just making the main plate thicker and
having done with it. The US SOUTH DAKOTA and IOWA spaced systems had the
main belt plate tilted top-over-bottom by 19 degrees (way more than other,
foreign belt plates), but could get away with that due to way the anti-torpedo
system below it was designed (also tilted considerably so that the lower in the
ship, the wider the anti-torpedo protection was; very logical) and the
relatively thick waterline anti-fragment (and, incidentally, decapping) STS
vertical amidships waterline outer hull (1.25" for SD and 1.5" for
IOWA). This use of non-parallel plates in a decapping system was not used
by anyone else, including in these 9.2" shell trials, since even those,
like the French RICHELIEU Class, that had an internal tilted main belt did not
have the thick hull in front of it required to decap any projectiles, so that
part of the system was missing completely. More work should have been
done on such non-parallel designs.
(5) ******BUT HERE IS THE
MOST IMPORTANT THING: >>>NOT ONE<<< intact penetration
occurred with the 0.98" NCA plate or any thicker decapping plate of either
kind, if it was spaced the standard 10" away from the main plate, no
matter what the main plate thickness was, either. Even though the
projectile nose was not shattering properly to get the big boost in main plate
resistance at low obliquity (20-40%, usually close to 30%, at right angles as
to the effective thickness increase of the main plate, gradually going down
until it disappears at 55 degrees obliquity, which obviously was not going to
be of any concern here), SOMETHING was happening to the projectile that caused
it to ALWAYS -- repeat, ALWAYS -- have its nose break up during the penetration
through the plate, this breakup spreading in most cases to the entire
projectile so that it was ALWAYS -- again, ALWAYS -- in many pieces when it
exited the plate back. What this spaced array does, it seems, even
against >>>THE BEST APC SHELL THAT EVER EXISTED IN THE BRITISH
NAVY<<< (!!!!), is to render these shells into pre-WWI AP Shot with
virtually no deep penetration ability if WWI-type internal splinter screen and
protective decks were used, thus saving the ship an ENORJMOUS AMOUNT of total
weight by allowing a much thinner waterline belt and requiring marginally
thicker internal bulkheads/decks just behind that belt to essentially ***STOP
COMPLETELY*** >>ALL<< ENEMY SHELL EFFECTS FROM REACHING THE SHIP'S
VITALS!!! What you want is to minimize the damage a shell does, here by
making the shell into small pieces, even if those pieces can get through the
main armor. A MAJOR improvement!
IV. ANALYSIS OF RESULTS
What is happening here with the
9.2" tests is due to the improved toughness of modern projectiles
versus modern armor. In WWI, the more brittle plates would be
defeated by a reasonably strong, tough projectile (the improved Midvale
Unbreakable US AP shells set as the new spec in 1916, for example) using a soft
AP cap that had no damage-causing ability of its own, but merely acted as a
shockwave absorber as the cap was crushed into a doughnut ringing the nose and
absorbed the impact energy moving sideways in the projectile nose that would
otherwise be trapped there, without which this shockwave would have cracked
that nose and starting the shatter process that would end up breaking the
projectile into pieces. Without that added damage to the projectile, the
older, brittle armors would fail afterwards first, as the projectile nose
tip continued to press harder and harder on the plate face directly under
it as the projectile's inertia built up due to the stopping of the nose mass
and this stopped projectile mass increasing as the shockwave moving back up the
projectile body toward the base gets closer and closer to the projectile base
(think a railway train with many cars suddenly having the front locomotive
engine stopped by something solid and the wreck moving backward from the front
as more and more cars get stopped too, slamming again and again into the rear
of the locomotive engine). Later face-hardened plates, including all
British CA made after 1930, had greatly improved toughness (crack resistance)
and the plate no longer was at a disadvantage as the inertia of the
post-initial-impact forces increased due to the increasing projectile inertia on
the impact point just described. This is why hard caps were now
absolutely needed against the newer face-hardened plates -- tests with older,
soft-capped AP shells against newer face-hardened plates showed that the older
shells, no matter how good they used to be against the older face-hardened
armors, no longer "cut the mustard" and failed against these new
plate types (the very superior, for their day, WWI US Navy Midvale Unbreakable
AP shells just mentioned are an example of this, shattering against the new US
Navy Thick Chill Class "A" armor developed in the mid-1930s). A
hard cap destroys the face of the plate as the cap is crushed, making a pit in
the plate and allowing the projectile, when it too is stronger, as the newer
projectiles were, to punch through the now-weakened plate in front of the
still-undamaged projectile nose, with in many cases negligible damage to the
projectile in the process. The harder the cap is, the better, as US tests
showed, resulting in the last versions of the latest 6" and 8" US
Navy WWII AP projectiles having extremely thick cap hardened entirely through
to 650-680 BHN, even harder than the surface layer of most face-hardened
plates! These new AP shells were greatly superior to their
otherwise-identical, but softer-capped, predecessors.
In this 9.2" decapping test
series, this superior APC projectile was hitting superior CA armor, but now the
AP cap, while still in-between the projectile nose and the plate face due to
the gap being too narrow to allow the cap to get out of the way properly, was
cocked off when it hit the plate and smashed itself to pieces, so when the
projectile rammed itself into the cap from the other side, the damage to the
plate was no longer a neat, symmetrical pit, but an irregular gouge with perhaps
much of the excavated face material caused by the cap's destruction no longer
even in front of the projectile nose (these tests were at 30 degrees
obliquity, remember, too). This greatly increased the stress on the
projectile nose when it hit the plate face itself shortly afterwards and,
because the plates were so much stronger now, without the properly-made deep
pit in the face prior to nose impact, the projectile nose broke as it pushed
through the remaining plate face. The pit that was made by the dislodged
cap was enough to help penetration somewhat, preventing full shatter on the
surface, but not enough to keep the projectile nose from breaking
afterwards. As a result, the projectile penetrated more easily than
without the cap, but the gain was only partial and the projectile nose and, as
the cracks spread from the nose backwards, projectile body was reduced to small
pieces by the strong plate, anyway. If the inter-plate gap had been big
enough to get the cap completely out of the projectile's path, the shatter
effect would have been complete and the NBL would have gone up significantly,
too. However, even "half a loaf is better than none" as far as
the plate is concerned in these tests. The ship using this system would have
been protected much better from major shell-filler-caused deep internal
destruction than if nothing had happened to the projectile during the
penetration, after all.
Since the Japanese 18.1" AP
projectile used a somewhat improved form of British-spec low-temperature solder
-- the US Navy experts were impressed by it, as it seemed to be easier to apply
than the US (and British) solders with identical results -- it will be decapped
just as easily as these US and British shells were and, due to the much larger
gap between the hull and belt plates (3' minimum or, for the 18.1" AP
projectile, 1.99-caliber minimum gap, even at the very top, getting wider lower
down), the cap will, according to Krupp results, no longer function at all,
causing the projectile nose and, as a direct result, body to shatter against
the main belt armor of an IOWA and giving the IOWA belt the full 30-odd-percent
thickness benefit of shattering an uncapped AP shell.
I hope this analysis has been
thorough enough to explain the situation vis-à-vis decapping of AP shells,
particularly the Japanese 18.1" AP shell being discussed here.
May 11 17 9:35 PM
******BUT HERE IS THE MOST IMPORTANT THING: >>>NOT ONE<<< intact penetration occurred with the 0.98" NCA plate or any thicker decapping plate of either kind,
May 12 17 2:03 PM
You seem to be hanging your entire argument
on a very thin thread.
Nathan based his results on tests
involving 18 different calibers/shells including 29 different shots just with
the 9.2” Mk12B as well as about a dozen more additional shots that included the
14” Mk8B the 15” Mk17B as well as a scale model of the Mk17B in 5.25” caliber. So….” No
exceptions. The caps were always
knocked off by the thinnest plates that was above the 0.0805-caliber value
since the shells all broke up…” Also,
there was never an “intact rebound” or “stuck
in plate” behind any de-capping plate (of at least .0805 caliber thickness) even
with the thinnest CA main plate tested. One must also assume , based on the extensive 9.2" trials, that the Brits considered the 9.2" results would accurately reflect those of the 14" and 15" shells as well.
believe what you will but the most important part of his answer, if you want to
be correct, was the last…… Since the Japanese 18.1" AP projectile used a
somewhat improved form of British-spec low-temperature solder ….-- it will be
decapped just as easily as these US and British shells were and, due to the
much larger gap between the hull and belt plates, the cap will, according to
Krupp results, no longer function at all, causing the projectile nose and, as a
direct result, body to shatter against the main belt armor of an IOWA and
giving the IOWA belt the full 30-odd-percent thickness benefit of shattering an
uncapped AP shell.
May 12 17 2:13 PM
May 12 17 7:01 PM
Maciej Chodnicki wrote:Problem is than NOT ALL broke up.
I have at last 4 examples of shells "not broken up", and even 1 example is enough to show that sentece "Always, no exception" is simply wrong, as there were exceptions.
So proof is broken. End of stroy. Simple math metodology.
May 12 17 8:46 PM
May 12 17 10:42 PM
Maciej Chodnicki wrote:Test in 1948 - same as noted by Nathan, but combination of external plate 80lbs, internal plate 240 lbs.
Shell 9.2", oblique 30 degree.
Striking velocity ~1600 fs - perforation in "condition to burst", striking velocity ~1680 fs - perforation in "condition to burst", striking velocity ~1710 - penetration in broken condition
What is interesting for me - striking in lower velocity resulted with better total performance.
Similar description (with various decaping plates lower velocity is better, as higher striking veocity will generate shatter, lower whole peroration) are from other primary soruces, but on smaller calibre guns "tank size" not "battleship size", so I'm a bit careful with extrapolation of those results to larger caliber. And one 9.2" example is not statisticaly significant, but corresponds well with those results with smaller guns.
Same series of tests, external plate 80 lbs, internal 220 lbs, shell 14", oblique 30 degree, striking velocity ~1110 fs - perforation in "condition to burst", striking velocity ~1190 fs - perforation in "condition to burst" (striking velocities taken from draving)
Test with 15" Mk II shell. Oblique angle 60 degree. External plate 1.5", internal plate 4.5", distance between plates 18", shell not decapped nor deflected. Striling velocity 1399 fs.
In the same series of tests single plate 6" thick broken shell, but disk was ejected from plate, so conclusion was that "plate was defeated", but damage to internal plate of decaping structure was larger than this on 6" plate.
Unfortunately I don't have exact descriptuion if shell was fully active after penetration of 4.5" plate or not. Reading from context, possibly was broken (very probable, and hardly surprising at this oblique), but descriptuion was clear. External plate 1.5" thick did not decaped, nor deflected this shell at this oblique. Mk II is WWI era.
Similar constructions, or Tressider decaping devices (some king of steel bar mattress - try to google "tressider device" and even patent could be found) worked against soft capped shells. Hard capped not.
What was construction between external and internal plates - I don't know.
From ADM 186/169
May 13 17 12:12 AM
May 13 17 9:00 AM
May 13 17 6:10 PM
The decapping plate test chart
for the 9.2" projectiles, original points plus the one I added, has FIFTY
-- repeat, 50 -- tests. ALL of them are consistent when the gap is over 1
caliber wide using the 9.2" tests using the 10" (1.09-caliber) gap
from the "egg crate" at 30 degrees.
The 80lb + 240-lb tests at 1600
ft/sec and 1680 ft/sec and 1710 ft/sec he mentions are there, but with one
"slight" defect in his reasoning: THAT TEST SET-UP HAD THE TWO
PLATES LAMINATED TOGETHER, NOT SPACED, AND THUS IS NOT A TRUE DECAPPING PLATE
TEST, JUST A LAMINATED PLATE TEST. Not relevant. In fact, there was
a fourth test against this set-up at only 1491 ft/sec that also penetrated
intact. Not effective by any measure.
German WWII tests found that for
KC plate up to half-caliber (7" for a 14" shell) at 20 degrees
obliquity and below an AP cap was not even needed to have no nose damage (the
projectiles were strong enough to handle this). The 14" test case is
hitting a CA plate only 5.39" thick at 30 degrees after going through a
1.96" decapping plate but, since they were using that same egg crate
setup, the 10" gap is only 0.714-caliber wide against that large
projectile, which is really less than the length of the cap from the tip to the
lower edge, so that it is not possible for the cap to leave the nose even if
decapped, since the cap skirt cannot move far enough away from the nose in this
narrow-gap case to have any effect. ANY gap created makes soft and tough
caps ineffective, but hard caps smash a pit into the plate face and even if the
solder is cracked, this will not change the effects of the cap on the plate
with the projectile nose still very close to the inside of the cap and simply
reseating itself when the cap stops moving when it hits the plate. It
seems that the gap has to be about 1-caliber minimum (9.2" tests with
10" gap) to cause the projectile breakup and 1.57-caliber minimum, from
the Krupp tests, to get the cap and nose to separate to the point that
projectile shatter occurs.
I have those results from the US
Army and Navy decapping tests during WWII and they again were very consistent,
with the only differences being when some projectiles had a better solder and
needed at 0.1605-caliber plate to decap them, these being most Army APC
projectiles used in Navy decapping tests, while most of them -- all US Navy AP
shells tested and most of the US Army APC tested by the Army itself -- only
needed 0.0805-caliber to decap it. When testing with 37-75mm APC shells,
the decapping effect was certain when using a 0.0833-caliber decapping plate in
the Army tests. The 75mm M61 APC shells, when decapped, were found to
increase the resistance to penetration by the next (main) plate, a 321 BHN
plate 2.5-3" thick at 35 degrees obliquity and up (frontal armor of
the SHERMAN tank, I assume), due to shatter by up to 5 times the needed
striking velocity when capped. Scale-model APC projectiles 0.3" in
diameter were made and confirmed the results with the larger projectiles.
The 15" Mk IIA APC
projectile was a soft-capped APC shell. How do you know that the soft cap
was not removed by the 1.5" plate? Where are the pieces of the
cap? A 1.5" HT/NCA plate will absolutely knock off the caps here
because THEY WERE NOT SOLDERED ON. At the time British caps were only
held on by crimping of the cap lower edge into or around pits or raised
bumps/ridges ringing the lower nose. The hard-capped 15" Greenboy Mk
IIIA APC shells added soldering ("sweating") to crimping of the cap
edge into shallow pits in a ring in the lower nose. US soft-capped AP
projectiles hitting thin KC plates at 60-68 degrees always shattered into
pieces and the plates also shattered, creating huge holes. It did not
make a difference if the cap was there or not, at such a high obliquity the
slamming of the projectile side against such a thin plate flattens out and
breaks the projectile body and this overmatches the plate even more, literally
causing it to explode downward due to the impact shock being far more than
these older, brittle armors could stand. They found that a 5" KC
plate hit by a 12" AP projectile at that high obliquity literally could
not be kept intact, both the shell and plate both shattered around the impact
point and no amount of lowering the striking velocity to the absolute minimum
that could be fired from that gun would stop it from happening.
May 15 17 9:16 AM
May 15 17 10:46 PM
May 16 17 12:51 PM
Addition to the last post
about 0.5 cal Fh armor almost invariably shatters any incoming uncapped projectile except at low obliquities (exception I know about is the german 7,5 cm Pzgr 39/43 with small cavity and possibly the 8,8 cm Pzgr 39/43-both with no AP Cap attached)
at low obliquities (0°-<20°) a penetration in shattered condition may occasionally occur.
(4) ... The US SOUTH DAKOTA and IOWA spaced systems had the main belt plate tilted top-over-bottom by 19 degrees (way more than other, foreign belt plates), but could get away with that due to way the anti-torpedo system below it was designed (also tilted considerably so that the lower in the ship, the wider the anti-torpedo protection was; very logical) and the relatively thick waterline anti-fragment (and, incidentally, decapping) STS vertical amidships waterline outer hull (1.25" for SD and 1.5" for IOWA). This use of non-parallel plates in a decapping system was not used by anyone else, including in these 9.2" shell Trials...
the outer hull plate appears to thin for enabling decapping of major naval caliber shells for sure.
May 16 17 1:46 PM
Thoddy wrote:--------------------------------------------------------------------------------------------------(4) ... The US SOUTH DAKOTA and IOWA spaced systems had the main belt plate tilted top-over-bottom by 19 degrees (way more than other, foreign belt plates), but could get away with that due to way the anti-torpedo system below it was designed (also tilted considerably so that the lower in the ship, the wider the anti-torpedo protection was; very logical) and the relatively thick waterline anti-fragment (and, incidentally, decapping) STS vertical amidships waterline outer hull (1.25" for SD and 1.5" for IOWA). This use of non-parallel plates in a decapping system was not used by anyone else, including in these 9.2" shell Trials...highly speculativethe outer hull plate appears to thin for enabling decapping of major naval caliber shells for sure.
May 18 17 8:16 PM
More thoughts relative to the 9.2" shell de-capping and penetration from Nathan,
I have this and other data, BUT
that "Perforated Whole & Fit to Burst" -- large black dot -- and
the "Lodged in Plate Whole with Adaptor Out (Not Fit to Burst)" --
(L)A -- result next to it were mislabeled on my document. So, out of
FIFTY (50) tests that I have, most of which are shown here, we have ONE (1)
that partly disagrees in that the cavity and base plug ("adaptor")
were not compromised. Note, however, the word "whole" is used
here, not "intact". In British ballistic test terminology, the
former means that the explosive charge in the cavity, if present, is still
functional, while the latter means no major damage to any part of the
projectile (including upper body and nose here), too. Thus, the front end
of that single Fit-to-Burst shell could have been destroyed (nose broken), but
the damage did not quite reach the cavity in that one case. Thus, the
damage may be the same as the other tests, just not quite as bad in this one
case. Since shatter and other forms of breakage are rather random in
degree from test to test, this is not surprising.
Ditto for the (L)A result, which
was enhanced as to impact shock being transmitted back to the base (cap did not
work properly here either), which is what causes the base plug to be torn out
in these projectiles (shell base damage cannot do this due to the much farther
forward placement of the base-plug attachment threads and the use of a second
threaded reinforcing ring to further lock the base plug in, which is why the
unique British "Patent Relief Base Plug" design was created),
possibly with nose broken damage, too. In this case, the end result was
the same as complete breakage.
Using one test that will allow
the shell to explode properly (if the base fuze was not damaged, which was not
tested here but is probably the case) to say that the large number of other,
consistent tests (Shell Broken/Not Fit to Burst) are invalid is kind of
bizarre, don't you think? "Follow the odds."
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