Tungsten Core Shatter Gap

[rexford]

Just like steel projectiles, tungsten core ammo can fail if it has too much penetration.

Test results presented in the report EFFECT OF IMPACT AND EXPLOSION show that tungsten ammo will fail if the velocity exceeds a critical value, which is a function of angle.

So when 6 or 17 pounder APDS hits the Tiger front hull at 100m, the APDS core may shatter and fail. And when 76mm HVAP blasts into the curved areas on the Panther mantlet at close range, a shattered nose may defeat the hit.

Based on the report text, hits that exceed the critical velocity abruptly increase the diameter of the penetration hole, which increases the velocity needed for penetration (more material thrown out of the way, more energy used).

What proof that these lab test results actually show up on the battlefield? Glad you asked.

Our book looks at APDS tests against Tiger tanks, and hits failed at velocities and angles that exceeded the critical velocity from the lab tests. And when hits succeeded, the velocities were below the critial velocity.

Like your mother always said, too much of a good thing is no good, and sometimes having too much penetration spoils the broth. Or something like that.

[ 07-14-2001: Message edited by: rexford ]

[Kanonier Reichmann]

Please, PLEASE... more, MORE!

I can't get enough of this info. Rexy. Keep up the good work!

Regards

Jim R.

[ 07-16-2001: Message edited by: Kanonier Reichmann ]

[Vanir Ausf B]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Kanonier Reichmann:

Sorry Rexy, but I thought this subject had been done to death.<HR></BLOCKQUOTE>

I guess I somehow missed all the other tungsten core shatter gap threads.

[PzKpfw 1]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Vanir Ausf B:

I guess I somehow missed all the other tungsten core shatter gap threads.<HR></BLOCKQUOTE>

Me to, wonder when the tungsten core shatter gap was discussed here.

Regards, John Waters

[ 07-14-2001: Message edited by: PzKpfw 1 ]

[Vanir Ausf B]

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1:

Me to, wonder when this was discussed.<HR></BLOCKQUOTE>

I was being sarcastic. It hasn't been discussed before.

[rexford]

Data table and discussion is presented on the Saumur Intranets site at following address

http://musee-des-blindes.intranets.com/disc/default.asp?command=detail&id=6615&thread_id=6534&l_form_id=

Log in as visitor, post should be under discussions, armor and projectiles, and then book errata page 6.

Previous shatter gap threads dealt with steel projectiles, this tungsten business is something new that I found in a report last week.

What sparked my interest is reading about how great tungsten ammo was, and how it was the end-all and be-all against German armor. APDS has a very high muzzle velocity and the hits appear to fall within shatter fail region quite often at close and medium range, which is CM country.

U.S. HVAP has muzzle velocities much lower than APDS and the chance for a shatter failure against Tiger or Panther armor is restricted, compared to APDS.

For those who hate technical hair splitting I have kept this thread simpler and in summary fashion. If one wants the details, go to Saumur Intranets and download the page with the table and write-up.

What I found interesting is how we think we have got things pinned down, and along comes another really odd and off-the-wall anomaly. I previously thought the penetration failures with 17 pounder APDS were due to flight instability, then along comes critical shatter velocity and it fits much of the failure data when rounds have too much penetration.

Did I detect a Mr. Bill accent in the "oh nooooooooo!" response. Well, rest assured that I have no plans to present endless technical posts that further refine intricate drawings on the head of a pin.

Elvis has left the building, and that is all for now.

[Vergeltungswaffe]

Don't ever stop, Rex. Striving to get things right is a noble and worthwhile pursuit.

I, for one, would love to see you become one of BTS' draftees from the community to keep making the world's best game even better.

[Ron]

Bring Elvis back!

What are the naysayers doing *here* anyway?

[rexford]

Rex (The King) says:

Thank you very much.

And here is a little number I call Shatter Gap Hotel, and it sounds a little like this.....

[rexford]

APDS is not so good.

Inaccurate quite a bit difficulty hitting targets in firing tests.

Shatter fails if impact velocity too high.

Decreases APCBC accuracy after APDS is fired.

Has about twice the constant aim scatter of APCBC ammo.

Not good.

All it has going for it is low slope effects when it does work properly. But how confident would crews be when a properly aimed shot at a stationary target at 500 yards misses by a mile. Would you want to face down a Tiger II and have your life depend on APDS flying straight and true?

And even if it did hit the turret front on a Tiger II, would it shatter into little pieces and anger the gunner.

[Freak]

Maybe thats why a Tiger II or Panther was rarley if at all ever taken out frontally in the entire war. Of course minus the shot trap for the panther, but from what has been said there is no record of a Kingtiger being penetrated frontally.

Darn...I shudder to think that Kingtigers and panthers get wiped out so easily by front turret penetrations so often in CM. What a PITA. Especially Kingtigers...I am amazed at the high percentage of turret hits in the game (knockouts). It seems extraordinarily high. I don't know how it worked out in the war, but the KingTiger seems to get alot of front turret hits compared to glacis. Maybe I should do a test. Damn KingTiger just aint worth its points with all the front turret hits (knockouts). Maybe I have bad luck. Damn, that front turret is small on the kingtiger compared to the glacis too. Oh well.

[rexford]

And now for a taste of T34 superiority over the Sherman.

The Russian Battlefield has an Archive report on comparative study of T34 and KV-1 at Aberdeen Proving Grounds. Russian 76.2mm was let loose on Sherman glacis, and penetrated it at 1100m!!!!!!!!!

Based on our numbers, Sherman 75mm APCBC would bounce of T34 glacis at point blank!!!

What gives, one might ask, since T34 penetration at 0° is inferior to Sherman 75.

1. Early Shermans have glacis with as many as EIGHT separate pieces welded together. Hit on or near a weld and resistance might drop.

2. Shermans use some cast pieces in glacis, and they have less resistance than rolled armor.

3. American armor very prone to flaws prior to late 1943

4. Russian 76.2 APBC penetrates less vertical armor than Sherman 75 but T34 gun penetrates ALOT MORE at high angles. This is due to wonderful flat nose rounds. Russian 76.2mm APBC penetrates about 40mm less vertical armor at 500m than American 76mm, but outpenetrates U.S. 76mm against 60° slope armor at that range.

T34 glacis armor is probably easier to penetrate with German 75mm than Sherman, but face to face T34 gun wins hands down against targets with sloped armor.

Unfortunately, Tiger has vertical armor, which brings T34 76.2 back to earth. Maybe Germans went for vertical armor on Tiger sides cause they knew (or guessed, or were lucky) about 76.2mm ability against sloped armor.

Granted that every T34 hit on a Sherman glacis at 1100m would not penetrate, but between that test at Aberdeen and the ability of T34's to cut open PzKpfw IVF2's and G's things are not that bad.

[PzKpfw 1]

Lorrin question if the Soviet 76mm flat nosed ammo was so great vs sloped armor why did it fail even at 100m vs the Panther glacis?.

76mm failings vs the Panther frontaly during Zitadelle, & even with 76mm sub-calibre rounds, was one of the main reasons, if not the main reason, the Soviet high command finaly accepted they needed a new tank gun.

Even the 85mm reportedly could only defeat the Panther turret frontaly by scoring a hit on the the small flat turret face below the mantlet.

Regards, John Waters

[kipanderson]

Lorrin, hi,

Once again, very, very interesting stuff. As I know you have realised I just absorb information on the WW2 Eastern Front like a sponge. And all matters on military technology.

From a careful look at the figures you have published on this forum it looks to me as though two APBC rounds, one Soviet one German, of “identical” diameter, identical mass and identical velocity would be of equal quality but at different angles. What I mean is that the German round would out perform the Soviet round against vertical plate by about the same margin that the Soviet round would out perform the German at 60 degrees. Have I got this “roughly” correct?

All the best,

Kip.

PS. Common-sense, and playing CMBO, indicate to me that there will have been “many” strikes at between 30 degrees and 70 degrees against the thinner side armour of Panthers and MarkIVs/StugIIIs. The Soviet way is not quite as eccentric as it may seem.

PPS. I have contacted your friend in France and pre-ordered. I know you must be asked all the time, but when do you think your book will be available? You must be bored with answering the question, sorry.

[PJungnitsch]

<BLOCKQUOTE>quote:</font><HR>Damn, that front turret is small on the kingtiger compared to the glacis too. Oh well.<HR></BLOCKQUOTE>

It's quite a design with most of the frontal area being very heavily sloped to deflect oncoming rounds, leaving only a small heavily armoured vertical portion with no shot traps.

[Jarmo]

<BLOCKQUOTE>quote:</font><HR>Originally posted by rexford:

This is due to wonderful flat nose rounds. Russian 76.2mm APBC penetrates about 40mm less vertical armor at 500m than American 76mm, but outpenetrates U.S. 76mm against 60° slope armor at that range. <HR></BLOCKQUOTE>

Does this mean Hetzers are very vulnerable to T-34?

Can a T-34 kill it just like that?

It would explain why german tankers much preferred the Stug.

[Freak]

Originally posted by machineman:

It's quite a design with most of the frontal area being very heavily sloped to deflect oncoming rounds, leaving only a small heavily armoured vertical portion with no shot traps.

Amazing photo. I don't think I have seen it up close as that....Amazing that there are so many front turret hits on that thing. The allied tank gunners must have amazing aim! I will have to check this out and do a test. Anyone know how frequent it was for an allied tanker to just hit the front turret on either the kingtiger or panther? More so on the kingtiger. Both of these tanks seem to get hit at the front turret more so the any of the other tanks in the game from my experience. (it may be that its what I notice) but I don't see how any allied tank gunner is going to hit that front turret with any frequency. Amazing! Its so small!

[ 07-14-2001: Message edited by: Freak ]

[Roksovkiy]

AchtungPanzer shows the king tiger with a

65mm mantle covering the entire front turret,

in addition to its 180mm turret.

The close-up picture above shows the turret with a cast armour mantle, that would give it a 245mm front turret.

For some reason SPWAW uses 215mm thickness for front turret value.

[rexford]

85mm APBC penetrates 145mm at 0° and 0m. Panther glacis resistance to 85mm APBC equals 182mm at 0° if good quality, 168mm at 0° with medium flaws.

No 85mm APBC penetrations against Panther glacis, and since 76.2mm APBC has less penetration against vertical, nothing for that gun either.

Hetzer 60mm at 60° resists 85mm and 76.2mm APBC hits like vertical plates of 145mm and 163mm, so no 85/76.2 APBC penetrations of good quality Hetzer glacis either.

APBC has low slope effects but that doesn't make up for low nose hardness, which depresses penetration all-around.

Hetzer is disliked due to tight fit of crew, and extremely vulnerable side armor. Plus gun didn't have a recoil mechanism, it was firmly attached to tank. In fact, Hetzer gun originally was same as 75L48 with a muzzle brake, but the lack of recoil mechanism caused wicked vibrations, so end of gun (with muzzle brake) sawed off. Shortened gun did not vibrate badly.

Hetzer muzzle velocity in CM should be 750 m/s.

APBC slope effect will make side armor on Panther, PzKpfw III and IV, StuG III and IV, etc. very vulnerable on wide angle hits.

[rexford]

At 500m, Russian 76.2mm APBC penetration at 60° is 41mm.

At same range, German 75L48 APCBC penetration at 60° is 45mm.

So 75L48 outpenetrates Russian 76.2 by 123 to 75 at 500m against vertical armor, but 60° difference is 45 to 41.

The Russian APBC slope effects are based on homogeneous armor, where projectile dig in allows flat nose to rotate round into armor instead of away from plate (ricochet reaction). With face-hardened armor, success or defeat will occur within a short distance of surface, which may not allow nose dig in.

Many German tanks use face-hardened armor which may not allow as much nose dig-in due to very hard surface layer, so we don't know if the APBC slope effects work against panzers such as PzKpfw III and IV (front) and Panther (side hull).

No one seems able to provide data for Russian APBC against face-hardened armor.

This is a serious data problem.

[rexford]

Face-hardened armor has a thin surface layer that is very hard. The armor defeats uncapped AP by shattering or cracking the nose.

Armor piercing caps have a fairly thick cap over the projectile nose and shoulder, with an air space directly above the vulnerable nose. This decreases the chance that face-hardened armor will crack the nose.

Flat nose rounds spread their impact on face-hardened armor over a larger area, which is less likely to crack the armor. Some sources state that face-hardened armor does better against flat nose rounds. Russian APBC is also low nose hardness, which might further decrease performance against face-hardened plate.

No one seems to know for sure if Russian APBC is good or bad against face-hardened plates. APBC would seem to have larger slope effects against face-hardened than homogeneous armor. We think.

Russian APBC has a windscreen ballistic cap, German APCBC has the windscreen ballistic cap and an armor piercing cap.

[Vanir Ausf B]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Freak:

Amazing that there are so many front turret hits on that thing. The allied tank gunners must have amazing aim! I will have to check this out and do a test.<HR></BLOCKQUOTE>

Freak, keep in mind that CM does not model different hit location probabilities for different tanks. In other words, the chance of hitting the turret of a KT is exactly the same as hitting the turret of a Mk IV, a Sherman, whatever. According to Steve this is a limitation of the game engine and won't change in CM2.

I actually did do a test on this and found that the turret is hit about 30% of the time on a non-hull down tank in CM. The upper hull was hit about 50% of the time with the last 20% divided between lower hull (12%), track hits and gun hits.

[Freak]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Vanir Ausf B:

Freak, keep in mind that CM does not model different hit location probabilities for different tanks. In other words, the chance of hitting the turret of a KT is exactly the same as hitting the turret of a Mk IV, a Sherman, whatever. According to Steve this is a limitation of the game engine and won't change in CM2.

I actually did do a test on this and found that the turret is hit about 30% of the time on a non-hull down tank in CM. The upper hull was hit about 50% of the time with the last 20% divided between lower hull (12%), track hits and gun hits.<HR></BLOCKQUOTE>

Thanks for the info Vanir B.I was unaware of this. Maybe it will make it into CM II.

Roksovkiy wrote:

AchtungPanzer shows the king tiger with a

65mm mantle covering the entire front turret,

in addition to its 180mm turret.

The close-up picture above shows the turret with a cast armour mantle, that would give it a 245mm front turret.

Is there any real validity to this? Rexford? Do you know anything about this? Kingtiger front turret armor thickness? Mantlet plate?

[ 07-15-2001: Message edited by: Freak ]

[rexford]

TIger II turret front and mantlet armor overlaps and openings can be best viewed on following site

http://history.vif2.ru/library/archives/weapons/weapons7.html

Photo's 7 and 8 show 88L71 hit on turret front at 400 meters going in the front (185mm at 10°) and out the back (80mm at 20°). Egads, that's over 281mm of effective armor resistance at 0°!!!!!!!!!!!!!! Time for another "underrated 88L71" thread?

Ah, but it also is an edge effect hit, where the round is fairly close to the turret front edge going in and leaves at the edge of a weld line. Hits on or near the weld line on Panther front hull (see Isigny tests) resulted in armor losing about one-third of its resistance.

It is also important to note that Tiger II turret front armor had a quality factor below 1.00 when it was hit by 100mm and 122mm projectiles, so add that to the equation, too.

Our book analyzes the Tiger II armor quality during the Kubinka tests, and it was about 0.85 for turret front but around 1.00 for hull side.

Our book has 222mm penetration at 0° for 88L71 APCBC at 400 meter.

But it is impressive having 88L71 go completely through the Tiger II turret via the front and rear armor. Sounds better than it is.

[Freak]

What about this extra 65mm of armor on the mantlet? Is this true? Would give kingtiger 185mm + 65mm armor thickness. Maybe an add on in the field?

[ 07-15-2001: Message edited by: Freak ]