rexford

Does Carius explain the use of the gun sight triangles for range estimation, or the use of battlesight aim where one sets the gun for 950m or 1000m and is theoretically able to obtain first round hits on targets 2m high at any range from 0m to 900m? The Panther 75mm would still miss more often than not at ranges beyond 700m, and it would be expected that the gunner might have as good, if not better, range estimate than the commander if the triangles were used. Two heads are better than one if the driver cannot see the target (a hulldown position would almost automatically limit or rule out a driver range estimate, especially if the tank were hidden in the brush).

Good question. The Germans required that the HE burster in the round be able to detonate on the other side of the armor, which suggests that almost all of the round had to get completely through and damage to the ammo would be minimal. A U.S. study of penetration criteria found that the percentage of the round which had to pass completely through the plate did not have much impact on the thickness. The criteria that a certain percentage of the round has to pass through for a successful hit is there to make sure that a hit where the round sticks in the plate, but a tiny portion of the nose breaks off and makes it through, is not counted as a success.

Here are Derek Ward's findings (from AFV News site) on the likely cause (yaw) of 17 pdr APDS accuracy and penetration problems, based on WW II research reports: "Well I got them in and digested them - alas they are still NOFORN and US Contractor/DOD only after all the years. I can not publish the data here but I will publish the report titles and the conclusions I have drawn from them without giving away the farm. The first is 'Yaw of a 3"/57mm sabot fired from the British 17pdr' Dated June 1943 - Author HP Hitchcock Memorandum Report 171. Projectile stability of this experimental round was rated as satisfactory. This was a 57mm APC core fired as trial ammunition. Yaw was comparable to standard APCBC in most cases. In this regard there appears nothing particularly peculiar about the 17pdr as a gun that would confirm or deny gas blowby of the projectile in the data. A limited number of rounds were fired, and I note nothing unusual in their performance expect for one problematical sabot separation. Thse second report is 'Exterior Ballistics Of The British APDS Shot For The 17pdr Gun' - Same author - BRL Memorandum Number 325 - Dated 5 Sept 1944. This report deals with the production ammunition, and gives a detailed break down of the shot components by weight/diameter/etc. The trial was run in a standard manner for the time - yaw screens coupled to rather crude electric switches. It is obvious from this data that projectile yaw is an issue. There were also some problems with APDS components hitting these components and destroying them during firing. Reviewing the data I can tell everyone that the degree of yaw is sufficient to result in marked penetration/velocity loss, certainly enough yaw to degrade penetration by the amount Lorrin has seen in some of the other test data (IMHO). The problem is obviously one of sabot/base plate separation, with resulting velocity degradation and loss of penetration on impact (angle of impact). There was a problem noted with the ammunition that might have been a quality control issue or lack of attention at the storage depot prior to delivery to the US. It would have had an impact on the performance of the ammunition in test given the nature of the problem, and I was suprised to see it in ammunition this recently off a production line. If that were typical of production ammunition then ammunition quality/storage/preparation is also a definate culprit...and could have acted in synergy to make the demonstrated problem worse. The quality isssue is such that it could have varied between lots and/or storage conditions. In summary - two major culprits - projectile yaw (a definate major symptom) and an issue with the ammunition itself - not pertaining to design - but to premature degradation. (demonstrated in the test ammunition, probably at least one of the causes??). Typical of all lots? I dont know...but it would have also played a role in this issue if it were. (hint: yes it did relate to the sabot and base plate) Given the yaw demonstrated with trial ammunition in the first report vs the production ammo in report 2, I don't think its a fault of the gun...its definately the ammunition...its definately a yaw issue...and if the test ammunition is an indicator then there is possible quality problem resulting in premature ageing. Regards All Derek" Good work on his part.

Where did you learn how to use a panzerfaust?

The Sherman fired an APCBC round with an armor piercing cap that was specifically designed to defeat face-hardened armor, which is what the PzKpfw IVH and StuG IIIG carry on their front aspects. The T34 with the 76.2mm gun fires a flat/soft nose projectile without an armor piercing cap. At 500m, the Sherman 75mm M61 APCBC can penetrate 95mm of face-hardened armor, the T34 76.2mm BR-350B APBC can penetrate about 70mm face-hardened. While the T34 76.2mm shoots APBC at 655 m/s, the round is inferior to the Sherman APCBC fired at 619 m/s. The face-hardened penetration data for T34 76.2mm ammo comes from Russian sources, and is verified by German firing tests (see my thread on the 1942 trials held at Kummersdorf). To my mind the argument is not over face-hardened penetration or modeling with regard to the T34 76.2mm rounds, it is the armor resistance of the 30mm/50mm and 80mm frontal armor. And the CMBB model where 85mm rounds bounce off of just about everything during 1943. JasonC has made several good, no, great points. The StuG IIIG front cannot be modeled as a few 80mm plates because the gun mantlet is flat and 50mm thick and a nice big target, the upper superstructure offers about 75mm vertical equivalent resistance, the low slope frontal plates on StuG IIIG contain many openings for bolts and vision areas creating low resistance edge effects, etc. In later games the Stuart 37mm round isn't as lethal because of the small diameter and the lack of an HE burster. The Brits found that it took one penetration with a 2 pdr to stop a PzKpfw II, but it usually took at least two to stop a PzKpfw III. Target size relative to projectile size is an important consideration.

The Tiger Fibel presents two procedures to increase the accuracy of first shot attempts, the use of gunsight triangles (2 mil and 4 mil distances) to judge target range by relative ratio's and a three man range estimation method (using averages) where the gunner's estimate is weighted twice as heavily. If a 3m wide target appears to be 4 mils wide on the gun sight, the target would appear to be 3 mils wide at 1000m and therefore is at 750m range. Using an average of three range estimates might increase the first shot accuracy by 50% to 60% over that of a single man's estimate. The question is whether the three man range estimating procedure as detailed in the Tiger Fibel is mentioned in the Panther Fibel, and whether such a method was used as a general rule in other German tanks or was limited to Tigers. The relevant Fibels can be found at: http://www.geocities.com/desertfox1891/pantherfibel.htm http://64.26.50.215/armorsite/TIGER-1%20FILES/tigerfibel.pdf Assistance on this would be appreciated. Thank you. Lorrin

The face-hardened penetration data for the Russian 45mm anti-tank gun is consistent with our estimates for the M1937 model with L46 barrel length, which fired AP at 760 m/s. 2 pdr AP was fired at 792 m/s but was a smaller and lighter round. 45mm AP weighed 1.43 kg while 2 pdr AP weighed 1.077 kg. There is a possibility that the 45mm anti-tank gun was the Model 1942 with a barrel length of L66 (I think) and a muzzle velocity of 820 m/s.

The 45mm ammo appears to be uncapped AP due to the face-hardened penetration thicknesses and the rate at which penetration falls off with range. The 45mm APBC round would penetrate more face-hardened armor and the penetration would fall off slower. My book estimates for 2 pdr AP face-hardened performance have 50mm at 0° and 500m, not around 40mm.

Here is a comparison of the German estimates converted to 0° penetration and 50% success versus Russian data at the same angle for the same guns (face-hardened armor appears to apply in both cases): British 6 pdr AP 100m: 109mm German est. vs 103mm Russian 500m: 91mm German vs 90mm Russian British 2 pdr AP 100m: 56mm German and Russian 500m: 38mm German vs 40mm Russian Russian 76.2mm Tank Gun (APBC) 100m: 83mm German and Russian 500m: 70mm German vs 72mm Russian Note: There is a possibility that the Russian penetration test figures are based on super-hardened BR-350B and should be increased by 6%. Russian 57mm Anti-Tank Gun (APBC) 100m: 129mm German vs 114mm Russian 500m: 121mm German vs 100mm Russian The Russian penetration data is not flagged as to whether it represents 80% success (6% thinner than 50% success thickness), 20% success (6% thicker) or the average of 20% and 80% (which would be 50%).

Here is a comparison of the German estimates converted to 0° penetration and 50% success versus Russian data at the same angle for the same guns (face-hardened armor appears to apply in both cases): British 6 pdr AP 100m: 109mm German est. vs 103mm Russian 500m: 91mm German vs 90mm Russian British 2 pdr AP 100m: 56mm German and Russian 500m: 38mm German vs 40mm Russian Russian 76.2mm Tank Gun (APBC) 100m: 83mm German and Russian 500m: 70mm German vs 72mm Russian Note: There is a possibility that the Russian penetration test figures are based on super-hardened BR-350B and should be increased by 6%. Russian 57mm Anti-Tank Gun (APBC) 100m: 129mm German vs 114mm Russian 500m: 121mm German vs 100mm Russian The Russian penetration data is not flagged as to whether it represents 80% success (6% thinner than 50% success thickness), 20% success (6% thicker) or the average of 20% and 80% (which would be 50%).

Miles Krogfus has discovered a graph that appears to present 1942 German firing tests of captured Russian and British guns and ammo. The graphed penetration data at 30° from vertical equals: ========================================= Russian 57mm anti-tank gun: 88mm at 100m, 83mm at 500m, 77mm at 1200m Russian 76.2mm tank gun: 60mm at 100m, 51mm at 500m, 45mm at 1200m Russian 45mm anti-tank gun: 40mm at 100m, 28mm at 500m, 18mm at 1200m Russian 45mm anti-tank gun: 71mm at 100m, 48mm at 500m (looks like HVAP) British 6 pdr tank gun: 70mm at 100m, 59mm at 500m, 49mm at 1200m British 2 pdr anti-tank gun: 40mm at 100m, 28mm at 500m, 18mm at 1200m Analyzing the data required a number of assumptions after reviewing the information, researching published WW II data and trying various alternatives: 1. All of the ammo appears to be uncapped AP rounds except Russian 57mm and 76.2mm APBC, and 45mm HVAP. This is consistent with the ammo types prevalent during 1942. 76.2mm APBC may be BR-350A. 2. Data is based on five or more consecutive penetrations, which represents close to 100% success probability and was a German standard for defining penetration. 3. The plate thickness for 50% success is about 21% greater than the 100% success thickness. Due to variations between rounds and experimental variations the actual difference for individual ammo types could be as low as 12% to 14% (0° penetration estimates could be high by about 7% in some cases). 4. Test armor appears to be face-hardened Applying the above assumptions to the data with slope effect multipliers from our book (Armor & Gunnery) results in the following 0° penetration figures for 50% success (half penetrate, half don’t): Estimated Penetration at 0° from Vertical with 50% Success =========================================== Russian 57mm anti-tank gun: 129mm at 100m, 121mm at 500m, 112mm at 1200m Russian 76.2mm tank gun: 83mm at 100m, 70mm at 500m, 61mm at 1200m Russian 45mm anti-tank gun: 56mm at 100m, 38mm at 500m, 23mm at 1200m Russian 45mm anti-tank gun: 115mm at 100m, 77mm at 500m (looks like HVAP) British 6 pdr tank gun: 109mm at 100m, 91mm at 500m, 73mm at 1200m British 2 pdr anti-tank gun: 56mm at 100m, 38mm at 500m, 23mm at 1200m Comparison with face-hardened penetration estimates from the Russian ARTKOM equation and published British data suggests that the above estimates for 0° penetration by AP and APBC are fairly consistent with national figures. It is possible that the Germans used a method with fewer than 5 consecutive successes for HVAP, so the above estimate for 45mm HVAP against face-hardened armor is highly suspect. The above estimates for Russian 76.2mm are very close to the ARTKOM equation estimates after they are converted to 50% success (80mm at 100m, 72mm at 500m, 63mm at 1200m). The 57mm APBC penetration drop-off with range is not consistent with Russian estimates of velocity vs range and may include an error of some sort (penetration on graph drops off too slowly). It is worth noting that neither the Russian 45mm or British 40mm guns would be expected to penetrate the 50mm face-hardened plates on the front of PzKpfw III and IV tanks at 500m range with uncapped AP.

Miles Krogfus has discovered a graph that appears to present 1942 German firing tests of captured Russian and British guns and ammo. The graphed penetration data at 30° from vertical equals: ========================================= Russian 57mm anti-tank gun: 88mm at 100m, 83mm at 500m, 77mm at 1200m Russian 76.2mm tank gun: 60mm at 100m, 51mm at 500m, 45mm at 1200m Russian 45mm anti-tank gun: 40mm at 100m, 28mm at 500m, 18mm at 1200m Russian 45mm anti-tank gun: 71mm at 100m, 48mm at 500m (looks like HVAP) British 6 pdr tank gun: 70mm at 100m, 59mm at 500m, 49mm at 1200m British 2 pdr anti-tank gun: 40mm at 100m, 28mm at 500m, 18mm at 1200m Analyzing the data required a number of assumptions after reviewing the information, researching published WW II data and trying various alternatives: 1. All of the ammo appears to be uncapped AP rounds except Russian 57mm and 76.2mm APBC, and 45mm HVAP. This is consistent with the ammo types prevalent during 1942. 76.2mm APBC may be BR-350A. 2. Data is based on five or more consecutive penetrations, which represents close to 100% success probability and was a German standard for defining penetration. 3. The plate thickness for 50% success is about 21% greater than the 100% success thickness. Due to variations between rounds and experimental variations the actual difference for individual ammo types could be as low as 12% to 14% (0° penetration estimates could be high by about 7% in some cases). 4. Test armor appears to be face-hardened Applying the above assumptions to the data with slope effect multipliers from our book (Armor & Gunnery) results in the following 0° penetration figures for 50% success (half penetrate, half don’t): Estimated Penetration at 0° from Vertical with 50% Success =========================================== Russian 57mm anti-tank gun: 129mm at 100m, 121mm at 500m, 112mm at 1200m Russian 76.2mm tank gun: 83mm at 100m, 70mm at 500m, 61mm at 1200m Russian 45mm anti-tank gun: 56mm at 100m, 38mm at 500m, 23mm at 1200m Russian 45mm anti-tank gun: 115mm at 100m, 77mm at 500m (looks like HVAP) British 6 pdr tank gun: 109mm at 100m, 91mm at 500m, 73mm at 1200m British 2 pdr anti-tank gun: 56mm at 100m, 38mm at 500m, 23mm at 1200m Comparison with face-hardened penetration estimates from the Russian ARTKOM equation and published British data suggests that the above estimates for 0° penetration by AP and APBC are fairly consistent with national figures. It is possible that the Germans used a method with fewer than 5 consecutive successes for HVAP, so the above estimate for 45mm HVAP against face-hardened armor is highly suspect. The above estimates for Russian 76.2mm are very close to the ARTKOM equation estimates after they are converted to 50% success (80mm at 100m, 72mm at 500m, 63mm at 1200m). The 57mm APBC penetration drop-off with range is not consistent with Russian estimates of velocity vs range and may include an error of some sort (penetration on graph drops off too slowly). It is worth noting that neither the Russian 45mm or British 40mm guns would be expected to penetrate the 50mm face-hardened plates on the front of PzKpfw III and IV tanks at 500m range with uncapped AP.

Thanks. Now I can play the tune on my harmonica and accompany the intro music. Makes me feel like marching. Only problem is finding the right key. Lorrin

Thanks, lots of good info and data which I hadn't seen before.

Anyone out there have any data on the weight and diameter of the German 75mm APCR tungsten core which would have been fired by the 75mm L43, L48 or L46 guns? Thank you. Lorrin

Thanks. There seems to be much in there that is good for our research. Lorrin

Test report on the Mycenius site includes a report of U.S. use of 57mm APDS during tests against captured Panther tanks: "5) 57mm Gun, M1 a) APC, M86 will penetrate the sides and rear of the 'Panther' Tank at 1500 yards. Sabot fails to penetrate front glacis slope plate and gun shield at 200 yards. Due to difficulty experienced in obtaining hits no conclusion as to the effectiveness of this ammunition was reached." Given the 100mm thickness of the curved Panther mantlet and the 200 yard range, there is a possibility that the failure of 57mm APDS was due to excessive yaw. There is another good AFV News thread on APDS ammo at: http://www.activevr.com/afv/cgi_bin/web-bbs/webbbs_config.pl/read/53369

Reports of Allied firing tests against captured Panthers and Tigers suggest that 17 pdr APDS hits were failing when the penetration was significantly greater than the effective resistance. The following lists identify the cases from two series of firing trials where over-penetrating 17 pdr APDS hits failed to defeat the armor, with angled hits converted to an equivalent vertical resistance. Jentz’ Germany’s Tiger Tanks, Tiger I & II ========================================== 17 pdr APDS attack on Tiger Armor Fails 82mm @ 50° => 180mm/0°, round hits at 3511 fps with 237mm/0° penetration 102mm @ 48° =>207mm/0°, hit at 3437 fps with 229mm/0° 102mm @ 48° =>207mm/0°, hit at 3215 fps with 209mm/0° 102mm @ 41° =>163mm/0°, hit at 3427 fps with 229mm/0° 102mm @ 41° =>163mm/0°, hit at 3602 fps with 245mm/0° Isigny Firing Trials ============== 17 pdr APDS attack on Panther Armor Fails (82mm glacis armor is assumed) 82mm/57.1° =>249mm/0°, 2 hits at 600 yards with 3700 fps and 255mm/0° penetration (glacis #2) 82mm/57.6° =>255mm/0°, 2 hits at 400 yards with 3781 fps and 263mm/0° (glacis #1) 82mm/57.1° =>249mm/0°, 3 hits at 400 yards with 3781 fps and 263mm/0° (glacis #2) 82mm/57.1° =>249mm/0°, 1 hit at 300 yards with 3823 fps and 267mm/0° (glacis #2) 82mm/57.1° =>249mm/0°, 1 hit at 200 yards with 3865 fps and 271mm/0° (glacis #2) 82mm/56.9° =>246mm/0°, 1 hit at 200 yards with 3865 fps and 271mm/0° (glacis #3) One explanation for the failures is flight instability due to yaw created by uneven shedding of the sabot petals, which was one of the suspected causes of accuracy problems. Another failure explanation is tungsten core shatter gap, where firing trials revealed that hits which exceeded a certain velocity at each angle shattered, resulting in the need for significant over-penetration for the hit to succeed. The tungsten core shatter gap curve identified the following velocities where shatter would occur and the penetration needed for success would be higher than the effective resistance: 0 degrees, 4093 fps 10 degrees, 3757 fps 20 degrees, 3458 fps 30 degrees, 3290 fps 40 degrees, 3234 fps (limited firing tests) 45 degrees, 3252 fps (limited firing tests) 50 degrees, 3290 fps (limited firing tests) 55 degrees, 3364 fps (limited firing tests) 60 degrees, 3589 fps (limited firing tests) The problem with the shatter gap theory is that the Panther failures turned into success in several cases when the penetration was raised to about 12% above the effective resistance, while the trials against Tiger show failures with 30% to 50% more penetration than effective resistance. This suggests that the most likely cause of the 17 pdr APDS failures against Tiger and Panther were due to excessive yaw.

John Salt, Please see new topic which I posted on 17 pdr APDS failures when penetration far exceeded effective resistance. Lorrin

When the U.S. First Army tested 57mm APDS rounds against captured Panthers in France (July 1944, see mycenius site for test report), using British made APDS that the U.S. had limited supplies of from D-Day through the end of the war, they had trouble hitting the targets and could not determine effective penetration ranges. Mycenius report can be accessed at: http://www.geocities.com/mycenius See test report #2.

No, it is new and is much appreciated. The British did not prepare new gun sights or range tables when APDS ammo was given out, but told the troops to use a certain fraction of the range for APCBC ammo.

Go to following site and thread for an interesting discussion of 17 pdr APDS problems and solutions: http://www.activevr.com/afv/cgi_bin/web-bbs/webbbs_config.pl/read/52422

17 pdr APDS was actually much better than U.S. 76mm HVAP against sloped armor, due to higher penetration (when it worked) and lower slope multipliers. Against a 100mm plate at 55 degrees, 17 pdr APDS would be resisted with an equivalent vertical thickness of 275mm while U.S. 76mm HVAP would be resisted with 345mm. Since 17 pdr APDS outpenetrates U.S. 76mm HVAP by a wide margin, 17 pdr APDS will be more effective when it works. In British tests with 17 pdr APCBC and APDS, 90% of the APCBC fell within a 4.1 minute distance of the mean point of impact, while 90% of the APDS rounds fell within a 11.5 minute distance. At 800 yards, the 90% distances relate to 0.95m for 17 pdr APCBC (90% of constant aim shots from 0.48m below to 0.48m above mean impact), and 2.68m for 90% of APDS (from 1.34m below to 1.34m above mean impact). For the same range estimate, 17 pdr APCBC would have some significant advantages. There is an interesting thread on the AFV News site that deals with the relative inaccuracy of 17 pdr APDS. I will try to get the address and date of the posts.

17-pdr APDS inaccuracy has been commented on before, but I can't recall anyone ever criticizing the penetration performance. What's your source for this, please? All the best, John. </font>