rexford

The discussion I'am in requires an exact figure, I think Hunnicut's Pershing or Sherman books might have the 90mm HVAP stats but I sold em both.

British and American tests with 17 pdr APCBC show that the round will not penetrate the Panther glacis even when the armor is of lower quality, and even at 0 and 200 yards range. So the Panther glacis quality should probably be about 0.95 against 17 pdr ammo. CMAK and CMBB make Panther glacis quality problems a random event that mostly occurs with Panther G's made during 1944 and 1945. Not every Panther has a deficient glacis, which accurately models what firing tests suggest. 17 pdr APDS is too accurate and too effective when it hits in CMBO. I have not looked at how it works in CMAK. Lorrin

Mr. Tittles, Do you have data on the tungsten core weight and diameter in the U.S. 90mm HVAP round (M304) used during WW II. I would appreciate your assistance if you have access to such data. Thank you. Lorrin

Firefly APDS should not be used, or the amounts should be radically decreased, cause the stuff was inaccurate and would often/usually fail to penetrate anything and everything if it did hit. There are tests against the Tiger 100mm and 80mm plates where 17 pdr APDS penetrated at a relatively low velocity and failed at much higher velocities. Against Panther, APDS is much too effective in CMBO. First off, the quality factor should be a function of plate thickness and projectile diameter, so instead of 0.85 against 17 pdr hits (APCBC and APDS) it should be about 0.95. Secondly, the APDS is too inaccurate and too irregular in penetration really be effective a whole lot.

Thanks for all the web site addresses and info, good stuff I never would have seen otherwise.

A question came up regarding the diameter and weight of the 90mm HVAP round used during WW II, and it would be appreciated if someone on the forum could post the information. My available references are not sufficient. Thanks.

Good point on the Tiger II turret front design, which I included in a post on the AFV News site.

Thanks for the site addresses, neat photo's. What it comes down to is would you rather have a Panther type mantlet, 100mm maximum thickness and some very good slope effects away from the center area, or the Tiger mantlet which clearly overmatches the penetrative effects of the Russian 85mm and U.S. 76mm guns firing steel AP type ammo? Being curved, the Panther mantlet has this advantage: when it defeats a hit it will do it by angle and slope effect, which means that the round damages itself and is deflected away carrying velocity with it, which reduces the impact on the Panther mantlet. The Tiger mantlet will defeat the round by just being too thick and causing the round to crush itself, or the round will really dig in. So there are advants and cons to each mantlet type.

Yes, a hit that digs in that much and transfers its energy to the mantlet by pushing armor out of the way would do quite a bit of shaking and rocking. But my point is that the thickness of the Tiger mantlet would prevent alot of those deep dig-ins by Russian 85mm and U.S. 76mm AP type ammo, hits that would completely penetrate or kick the heck out of the Panther mantlet. As the penetration stats show, Russian 85mm and U.S. 76mm won't do much to the Tiger mantlet at 500m and beyond, but they can fry the Panther mantlet on center area hits or shake things up real good on partial penetrations.

One point which came out during a discussion is that the Panther mantlet may weigh about the same as the Tiger mantlet even though the Panther has a thinner casting (100mm max versus 150mm+ on Tiger). If the Panther mantlet is assumed to be half a circle with a 92.5mm average thickness (it tapers down to 75mm or so at the edges), the total mass would equal 92.5mm x pi x radius x width, or about 145mm x height x width. If the Tiger and Panther mantlets ahev about the same height and width, their weights would seem to be comparable. The difference in ballistic resistance would make the Panther mantlet more vulnerable than Tiger on hits within the center half (within 30 degrees of apex) and less vulnerable on hits above and below the central area. And the curved shape would create a shot trap where hits could be deflected down onto the hull top where they could penetrate. Rounding of the Panther mantlet may make gun balance and elevation easier, but I am not sure.

With regard to my previous message, British tests with German 75mm and 88mm APCBC showed that the burster would be damaged and fail to work properly on 45 through 55 degree hits. This may explain why Shermans and T34's would not be 100% protected by added spaced junk, the German bursters did not always work.

The point which you overlook is that the impact with a 20mm plate was sufficient to set off the burster. Another point which I raised which you did not acknowledge is that a plate thickness of 6mm is sufficient to set off the 88mm APCBC fuze. That thickness would not create or require much of a G force, would it? Going through a 6mm plate sets off the burster. Seems extremely sensitive to me. Would ground impact be sufficient? Maybe yes, maybe no. I suspect that the 6mm sensitivity of 88mm APCBC fuzes may have been designed to permit detonation of armor piercing rounds inside lightly armored armored cars and halftracks, and the rapid detonation of the 75mm Sherman APCBC round after partial penetration may have been a similar tactic to allow explosions inside German light armor. I also suspect that large naval rounds required more of an impact than the 88mm (where a 6mm plate is required) to set off the burster, which explains why hits on destroyers would go completely through the ship without a detonation inside (minimum thickness for detonation and delayed detonation which would not be a problem against heavy armor). And why skipping off water might not be enough with a naval round. I have also read of armor piercing penetrations of light armor where the round passed completely through the vehicle and detonated outside the car. However, if early detonation of German APCBC bursters (before full penetration) were the general case than placing wheels, tracks and other relatively thin things on the front of a Sherman, with a short space to the main armor (6" or so), might be expected to defeat Tiger and King Tiger hits through detonation of the sensitive APCBC burster. Did the Allies miss an important tactic which might have rendered the German Big Cat guns impotent? It's possible that the 20mm spaced plate on PzKpfw III set off the burster because the hits were at 30 degrees or so which caused the round to jerk and change direction as it penetrated. The radical change in direction might have contributed to the projectile damage. For Sherman 75mm and Russian 122mm armor piercing rounds with bursters to detonate against a spaced 20mm plate with a 6" spacing does suggest that the round detonated prior to full penetration. But note that in both cases the detonation of the burster was sufficient to cause defeat of the hit by damage to the projectile. The 50mm main armor was able to defeat the fragments. You're both right (detonation of Sherman 75mm APCBC and Russian APHE occurs with less than full penetration) and wrong (HE burster is incapable of severely damaging the projectile and leading to defeat, 75mm APCBC had pre-detonation problems and various other subjects). Looking back at the original issue which started all of this, an 88 hit next to a Sherman that supposedly rocked the tank, it seems most likely that the round was HE as you originally theorized. I would also note: The 90mm APCBC detonation on the armor surface in the tests before penetration was a flaw which was corrected, and Sherman 75mm and Russian 122mm AP detonation prior to complete passage through armor may have been a design tactic. Or it may have been a production or design problem. The British use of armor piercing rounds without bursters, and the removal of the burster in U.S. 75mm APCBC ammo, may have been based on spaced armor considerations. And the Brits and Russians acknowledged that a 6" space was sufficient to set off bursters and defeat hits. If you would be more open to other folks' comments it would help. [ June 29, 2004, 04:55 AM: Message edited by: rexford ]

That's a good question that deserves an answer. Right now I don't know but will look into it and maybe some others will as well. Some of the web sites that deal with the German gun sight make the assumption that the triangle sighting marks were generally used for range estimation. Haven't seen anything on the three man estimating procedure outside the Tiger Fibel. Thanks for raising an important point.

The triangles on the Tiger gun sight were expected to be used for range finding, and we did some figuring as to the expected accuracy of the method. Assuming that the gunner wasn't too great with fractions and didn't have a hand held calculator or slide rule, we noted the following: 1. Assuming 3m frontal width works great for a tank facing directly at the Tiger. As the angle increases above 0 degrees the width goes above 3m as side armor contributes to the width: Tiger looks straight at T34 hull front: 0% error 5 degrees angle: 17% error (actual width is 3.5m) 10 degrees: 33% error (actual width is 4m) 15 degrees: 50% error if assuming front view, 33% assuming side 20 degrees: 18% assuming side and 63% assuming front view 25 to 90 degrees: 0% to 12% error range with 8% average if side view is assumed by gunner The risk here is that the gunner will assume the wrong facing, such as when a T34 is at 1200m and the angle is 30 degrees but it looks like a front facing. The starting error in that case would be 80%! 2. The second series of tests placed a T34 at 30 degrees to a Tiger and predicted the range that the Tiger gunner would estimate based on the perceived target width. The T34 at 30 degrees angle projects a width of 5.6m, or 5.6 mils at 1000m. Looking at ranges from 450m to 1200m with 50m jumps, and with the Tiger crew assuming that the T34 was 6m width even though the actual presented width was 5.6m, the range of errors was 0% to 23% with an average of 9%. Accounting for human error might increase the average error to 15%, which is still below the average error of British tankers (20% to 25%). 3. As an example of how the system works, assume the T34 is at 30 degrees angle and is at 650m. The perceived width on the gun sight is 8.6 mils, so the estimated range equals 1000m x 6/8.6 or about 700m. 4. Using the triangles on the Tiger gun sight would appear to result in fairly good range estimates as long as the gunner worked out and rounded the fractions reasonably well, and did not lose his cool, and did not mistake a predominately front view with a side view (in most cases both front and side armor would be presented, but the gun sight distinction between the two might not be especially clear in all cases). 5. The range estimates presented by the Tiger gunner would be given twice the weight of the estimates made by the commander and driver, so the triangles would help to further improve a system which already had many advantages (the Tiger Fibel states that three sets of eyes are better than one, which is statistically true). 6. One problem area is that the T34 is associated with a 3m height, although the T34 M43 appears to have been more like 2.4m. Done correctly and cooly, the Tiger range estimating system would work much better than the single man methods used in Allied and Russian vehicles.

I guess you conveniently forgot about the 122mm APHE trials against spaced armor, which disproves your point. A 20mm plate isn't go to do much damage to a 122mm APHE round. The 122mm APHE isn't go to bulge much due to a 20mm thick plate, so it was the contact that set off the HE burster and not some theoretical stuff about shell casings bulging and what have you. Naval rounds skipping off water has nothing to do with WW II armor piercing anti-tank ammo. Good bye on this thread. [ June 29, 2004, 04:54 AM: Message edited by: rexford ]

No, no, no! The test data shows that the burster in APHE will detonate and go off after passing through a 20mm plate, and then the round will not be able to penetrate a 50mm plate 6" behind the first. This is not predetonation, it is the normal action of an APHE fuze where the burster goes off after the round passes thru the armor. The 90mm APCBC-HE round predetonated when it hit test plates during May 1944 trials, where the round failed to penetrate because the burster went off BEFORE penetration. In the 75mm APCBC and Russian 122mm tests the burster went off after penetration, as it should. Bye.

You were plain out wrong regarding my ability to analyze things, and calling my questions to you silly will not change things. Asking a question is not taking a side or making a definite statement, so it is not as silly as you think. It is logical to ask if APCBC-HE will detonate on glancing ground hits since HE will. Prove that it wouldn't detonate. Don't just talk, show us the money! If you are so sure it will not detonate substantiate your statement. I previously invited you to research the issue and get back to us, and eagerly await your findings.

Notice that Mr. Tittles said the mantlet hit in the image "could throw off the zero", and he didn't say it definitely would. No one can say any hit would definitely do anything, cause short range Panther hits on Shermans failed due to cracked projectiles and even the thickest armor could send fragments flying inside a tank. That being said, the Tiger mantlet would have less of a chance for bad results on defeated hits due to its thickness and mass. With a minimum mantlet thickness of 135mm, the Tiger mantlet would defeat hits from M10 3" APCBC at 750m with a comfortable margin (109mm penetration, 135mm to 197mm resistance). The Panther mantlet is 100mm at its thickest, and on a 25 degree impact would present about 120mm effective resistance. Given the mass and thickness of the Tiger mantlet, the 3" APCBC hit on the Tiger mantlet would have a higher probability of using alot of its energy destroying the projectile than against the Panther. There would be a higher probability that the hit would bore into the Panther mantlet and shake the heck out of the lighter mantlet. There would be a higher probability of the M10 hit throwing off the gun zero on the Panther. There would be a higher probability that the M10 hit on the Tiger would suffer severe damage and bounce away without digging in very far. Heavier mantlets would seem to have many advantages over lighter mantlets. And it should be noted that the 100mm to 110mm curved mantlets on Panther and IS-2 tapered, with the Panther mantlet reducing to 75mm at the upper and lower edges. There are many reports of single Tigers taking all sorts of hits from 57mm and 76mm guns after being surrounded and not only blowing away the enemy but driving off afterwards. Thick armor helps. Mr. Tittles is right that some hits have enough penetration to dig deep into the mantlet and shake things up really well, but the Tiger mantlet is probably going to do better against rounds it can defeat than the Panther. That's my point. As an aside, the curved 100mm Panther mantlet will present over 120mm resistance on half the hits and over 150mm on a good percentage of hits, and that is the benefit of a curved mantlet. The resistance can be very high on hits near the upper and lower edges. But around the center area, and considering the cast armor, the Panther mantlet puts up less than 110mm resistance on a good share of the hits.

While I wasn't go to dignify your posts with a response, the personal comments above deserve one last post: 1. the Panzer IV Universe data on 75mm APCBC burster weight is wrong, the data was prepared in the 1960's and has been eclipsed by actual measurements taken during the war. 2. I lack logic and technical skills? Here are a few tidbits from my personal background: licensed professional engineer 30 years studying armor penetration/projectiles cowrote book WW II Ballistics: Armor & Gunnery Derived slope multiplier and armor quality system used in Combat Mission games Contributing editor to Campaign Magazine in 1970's and early 1980's Over 35 published articles on WW II tank combat Created the AFV Kill system used in Advanced Squad Lead Member of playtest team on over 10 games Like most of the other things you recently posted, your comment about my logical and technical skills is based on what appears to be an insufficient research effort.

In a manner of speaking, yes, although I tend to trust them more than internet sites. The timing on an APHE shell is important because it is intended to detonate inside the tank. To skip a shell into a tank would require: * That the ground is hard enough for the round to skip off * That the angle is acute enough that the round will skip without being too damaged or the trajectory be altered too much (i.e. if the direction of travel is still along the long axis of the shell * That the target tank is close enough that the shell will not detonate prior to hitting it. OR * That the impact with the ground is not sufficient to trip the fuse. OR * That even if detonated, the charge does not significantly alter the shell mass/shape/trajectory As to whether the HE in an APHE shell is sufficient to reduce the shell so that it is not capable of further penetration, one would need to know the proportion of shell mass that is HE. If it is comparable to the US 75mm APCBC-HE, then one can conclude that the detonation would radically alter the shells mass. Real world experience? Of skipping 88mm APHE shells into tanks, no. I have no experience of that. Am I probably a student, or probably have little real world experience. As we're working with theory and history, it will suffice to prove me wrong rather than say that I'm wrong because I'm inexperienced. </font>

Last response to your posts on this thread for me. British say German 75mm APCBC had a 14 gram HE burster based on their analysis of actual combat rounds, data which you previously quoted had 82 to 83 grams. Your data looks incorrect. That's the point. I thought you would compare your previously quoted numbers to the figures I had posted but I guessed wrong.

You missed the point of my statements on HE shells, and need to correct your statement about HE shells being fuzed for delay detonation. First, I discussed HE shells to show you that a glancing blow on the ground can set off an HE shell fuze, which shows that bouncing off the ground can generate enough of a force to detonate a round. Sufficient G's from a bounce off the ground, which appears to be "severe enough" to set off the burster. Which suggests that your opinion may not be correct. Secondly, HE shells can be set for instantaneous detonation. Suggest you get access to ARMORED FORCE MANUAL, TANK GUNNERY, April 22, 1943, which is U.S. FM 17-12. Pages 19 and 20 of the FM disprove your above statement and suggest that you should do more research on projectiles: "The PD fuze M48 used with the 75mm shell, HE M48, is a combination superquick and delay point-detonating duze. The shell comes at superquick". "It may be set to burst 0.05 seconds after impact by turning the slotted key on the side of the fuze so that the slot points to the word DELAY stamped on the bidy of the fuze. Always set the fuze at DELAY before stowing the ammunition." Superquick action: is so sensitive that the shell detonates immediately upon impact. Therefore, when striking armor plate, a gun shield or a building the shell will burst before it can penetrate. Delay action: 0.05 second delay before bursting when it strikes light armor, gun shields or buildings. Based on my analysis of the Sherman 75mm APCBC=HE going through the 20mm spaced plate and detonating before it reaches the 50mm main armor, the delay for armor piercing ammo is very short.

British report M.69144/4 No.1 analyzes German 75mm and 88mm APCBC ammo: 75mm APCBC fired by Kwk 40 14 grams HE burster, minimum armor thickness to set off burster is 12mm 88mm APCBC fired by Pak 43 60 grams HE burster, minimum armor thickness to set off burster is 6mm German 75mm APCBC had one of the smallest HE bursters by percent weight of any WW II ammo, 0.2% of projectile weight. Suggest that Mr. Tittles recheck his source for the 82 gram to 83 gram HE burster in 75mm APCBC. Looks terribly high. [ June 27, 2004, 09:29 PM: Message edited by: rexford ]

First off, the German 75mm APCBC-HE round is not a good comparison to the American 75mm APCBC-HE, for two reasons: 1. German 75mm has one of the smallest HE bursters for a WW II round on a percentage basis, Sherman 75mm APCBC burster is quite a bit larger 2. German 75mm APCBC is one of the hardest steel armor piercing projectiles of WW II, Sherman 75mm APCBC is one of the softest. Sherman 75mm APCBC with HE burster is going to detonate with a bigger bang, and the metal will tear apart easier, than the German 75mm APCBC. Suggest you go to following site and click on U.S. Army Test #1 for a discussion of the tests regarding detonation effects when 75mm APCBC is fired against spaced plates: http://www.geocities.com/mycenius Regarding ground hits and burster detonation, the Sherman gunnery manual suggests that HE ricochet fire be used against troops in trenches where the round is bounced off the ground and explodes in the air. The HE round burster is set to delay so it won't go off as it hits the ground. If an HE round will detonate on a glancing hit against the ground, why wouldn't APCBC? I don't have the time or interest to research any of this anymore but would be interested in hearing what others come up with. [ June 27, 2004, 03:58 PM: Message edited by: rexford ]

Mr. Tittles said: "Are you sure you havent confused the AP with the HE? Why don't you research that?" Already responded.