rexford

PzKpfw IVH had 80mm of face-hardened armor on the front hull at 10°, hit it at 30° side angle with 75mm APCBC and resistance is 102mm at 0° of face-hardened armor. 75mm APCBC penetrates 102mm of face-hardened armor at 100m and 0°, which is an exact match with the data for Sherman 75mm vs PzKpfw IVH at 100m and 30° side angle (face-hardened armor). When 76mm APCBC hits 80mm at 10° at 30° side angle, resistance is 102mm at 0°, Sherman 76mm penetrates at 1100m.

When Germans indicate 60° impact, they are talking about a shot with 30° side angle, firer is sitting 30° from straight-on against the target. If hit is on enemy tank front hull, 60° angle to Germans is a firer sitting 30° from direction of hull facing.

First IS-II tanks carried BR-471 AP rounds as only armor piercing type, and this continued for awhile. Many IS-II tanks carried mostly BR 471 for quite awhile, others had BR 471B APBC. Big difference in effectiveness against sloped armor between 122mm AP and APBC.

Russian Battlefield and some old articles by Valera Potapov put IS-2 rate of fire well below 3 with improved breech block under ideal conditions. Will look into turret removal process. Good question.

3 rounds a minute sounds high for IS-2 with improved breech.

Didn't Hitler change his name to that from something else? Shicklegrubber or something like that?

Thanks Jeff. Flat nose APBC apparently had break-off grooves just below the flat nose that would remove the nose in case of violent impact, such as a high angle hit or face-hardened armor at an angle. In effect, this would act like a quasi-armor piercing cap where the initial damage upon impacyt is limited to a "throw away" armor cap and the main body would then be in perfect shape to pound the plate. This break-away tendency would probably boost the penetration ability against face-hardened armor on angled hits, but might do little on hits at vertical angles. The identification of the break-away grooves is a major find and I thank you for bringing this to our attention. Lorrin

If one looks closely at the Russian assessment of Panther penetrations at Kursk, see where they assume 85mm for Panther glacis and 65mm for nose. We always assumed that Russians measured alot of Panthers and found that the actual thicknesses were greater than 80mm and 60mm. Brits use 85mm and 65mm, Americans use same. Seems only the Germans regularly used 80mm and 60mm. This is what we found when we went over actual measured thicknesses on German tanks with 80mm and 60mm armor, the actual thickness was much larger (and greater than the 5% max allowable deviation that the specifications supposedly imposed).

Since APBC already has a flat nose why would one want to have the nose break off to provide a flat nose? The remainder of the round would not have enough mass left to do much of anything after the forward part broke off and bounced away. Are the grooves you are looking at for the rotating bands? A fellow in Australia noted that uncapped Russian AP may have had grooves to knock off the pointed nose on impact, producing a quasi-flat head round.

45mm guns had APCR during Kursk battle.

In British test, German 75mm APCBC penetrated 37% more armor at 610 m/s than Russian 76.2mm APBC at 0° impact. Difference is due to nose hardness (German at 61 Rockwell C, Russian at 52), projectile weight (German round a little heavier) and nose shape.

Jeff, Thanks for posting that info from British report. The Russian AP grooves and the part about the nose falling off to improve angled penetration is a new one for us, and may account for some battlefield results. The grooves in the APBC ammo seem to be there to hold the ballistic windscreen cap, where it is crimped into place. See special notes in our book after page 63, the 76.2mm APBC drawing where the ballistic cap joins the main body of APBC. The part about the nose falling off on an angled hit to improve penetration seems to be about the uncapped AP round with a pointed nose even though the report does not state that fact. The amazing thing about the report is that they don't mention the flat nose on APBC, and miss the extremely low slope effects which greatly improve penetration on angled hits. The British had 76.2mm APBC ammo during the war (came with T34 and KV-I they were sent), they shot it against 0° slope armor and reported results, yet nothing in that report Jeff obtained on magnificant slope effects. 76.2mm APBC fired at 680 m/s could penetrate almost as much 60° armor at 500m as German 75mm APCBC fired at 750 m/s. But at 0° impact German 75mm outpenetrates Russian 76.2 by 123mm to 75mm. Flat noses buy excellent penetration at angles but kill the effectiveness when target impact has small angle. Russian Battlefield indicates that Russian 122mm AP (one with grooves so nose leaves round, leaving it "flat nosed") could not penetrate Panther glacis during initial combat. Then it penetrated at about 650m. Finally, late 1944 found 122mm AP shattering a Panther glacis at 2500m!!! [ 07-19-2001: Message edited by: rexford ] [ 07-19-2001: Message edited by: rexford ]

76.2mm Russian APCR not available till October 1943, so none at Kursk. Our figures for Russian APCR penetration are based on three data sources: 1. comparison of all published figures we can find 2. DeMarre estimates for all sizes from most valid figure (45mm would be estimated from 76.2mm, if 76.2mm looks the best) 3. Correlation with listed penetration ranges in Russian and German sources, which is usually (but not always) a calculation based on best available info. We took what looked like the best after reviewing all three lists. At one time we had core diameters and weights for Russian tungsten core ammo, so DeMarre estimates were probably very good and they turned out close to other figures that seemed creditable.

Any data on the ranges where those Panther penetrations took place?

45mm tungsten core ammunition at 0° 45mmL46 anti-tank gun 94mm at 100m, 84mm at 250m, 70mm at 500m 45mmL66 anti-tank gun 108mm at 100m, 97mm at 250m, 81mm at 500m Both 45mm guns could hole the Panther mantlet at 50m with tungsten core ammo and a hit near the mantlet vertical center.

After the Panther attack where tanks got caught in bad terrain and were blown away by Russian 45mm, 76.2mm and 85mm guns, the Russians went out and analyzed the guns, ammo and impact angles that made armor penetrations. Ranges were not listed although one 45mm APCR hit was at 50m. For those who like that sort of thing, the following is a summary of the widest wide angle penetrations by 76.2mm APBC that occurred against Panthers (source in in Archives section of Russian Battlefield, look for Panther damage report): http://history.vif2.ru/library/archives/losses/losses6.html Tank 95 Rear hull 40mm penetrated at 50° side angle Tank 122 Upper side hull 40mm penetrated at 50° side angle Turret side 45mm penetrated at 45° side angle Tank 142 Rear hull 40mm penetrated at 65° side angle Tank 170 Upper side hull 40mm penetrated at 60° side angle Tank 615 Upper side hull 40mm penetrated at 50° side angle The large compound angle penetrations are only possible, in many cases, with flat nose APBC. Flat nose APBC is less effective than Allied APCBC against vertical armor, but APBC really burns em on angled hits. Based on little or no real data, I'am guessing that the ranges were 100m to 200m. There were no 45mm APBC penetrations of Panther upper side armor. A 65° side angle hit on rear armor is odd, since the great majority of the tank target would have been side armor.

What is the address for the Achtung Panzer data for Tiger II which suggests 65mm added armor to turret front. Thanks.

We have never seen a photograph of a Tiger II with added armor to the turret front, the mantlet only covered the area immediately around the gun opening. WW II tanks had trouble adding turret front and mantlet armor due to the impact it would have on turret balance and weight on front wheels. This is why Pzkpfw IVH turret front armor is not increased when hull front goes from 50mm to 85mm, why IS-2 tanks only have 100mm turret front/mantlet, why 76mm armed Shermans only have 89mm mantlet, Panther mantlet is only 100mm thick, etc. Tiger E mantlet has minimum thickness of 135mm in center areas, upper and lower mantlet edges thin to 100mm but these are backed up by a space and then the 100mm turret front armor. Tiger mantlet is much thicker than the hull front, but Tiger E is an unusual example. Tiger II turret speed was slow enough, adding another 65mm to turret front would throw balance out and do all sorts of bad things. The only tank I can think of that had added resistance to turret front is PzKpfw IIIL and M, where 20mm spaced was added in front of turret and upper hull. I bet the PzKpfw IIIL,M turret rotation speed decreased.

We look at reports before we accept them as reasonable, and we analyzed the penetration range results. It looks valid, and we wrote up our findings in our book. We took the penetration range info for 85mm and U.S. 76mm guns against the Tiger II side armor and analyzed the data, filling in some of the missing data from the bits and pieces (76mm penetration range is longer than 85mm, penetration range for both guns was from XXX to XXXX, etc). The resulting analysis showed the penetration range results to be in line with U.S. penetration data for 76mm APCBC, and with our data for 85mm projectiles. The Tiger II firing tests at Kubinka appear reasonable and realistic for WW II ammunition.

I have posted the actual test results for 122mm APBC (angles from 0° through 70°) on the Saumur Intranets site as a group document, document access is limited to members. Site address is http://musee-des-blindes.intranets.com/login.asp?link= [ 07-15-2001: Message edited by: rexford ]

Discussions with Nathan Okun on Russian APBC resulted in the following notes: 1. Russian APBC may be an attempt to gain the advantages of an armor piercing cap without the actual cap 2. Flat nose APBC may be more vulnerable to shatter, and may be less effective than APCBCC against face-hardened armor at vertical 3. Rounds without noses are often more effective on highly angled hits due to the energy that noses absorb and use going through the armor What data is out there, particularly in Jentz, regarding penetration ranges for 76.2mm T34 hits on PzKpfw III and IV?

The following address might be a faster way to access the tenth post on the thread, which analyzes the relative differences when different type rounds strike 60° armor: http://musee-des-blindes.intranets.com/r.asp?a=10&id=6623&t=6602

In other words, APBC kills thin armor on highly angled hits.

I have posted a drawing on the following site that illustrates the impact and slope effect differences between AP, APC, APCBC and APBC when they strike 60° slope armor: http://musee-des-blindes.intranets.com/login.asp?link= Sign in as a guest, go to discussions, armor and projectiles, and the 122mm charts and high angle slope effects thread. The post will be the tenth on the thread, and the .gif file is attached. At 60° and T/D=0.8, APBC and APCBC slope effects are about 5% different (APBC is lower), and AP is much higher. At 60° and T/D=0.49, APBC slope effect is much lower than AP, and AP is lower than APCBC. [ 07-15-2001: Message edited by: 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.