We have velocity versus range data for most German guns, APCBC, HE and APCR, as well as American data in TM 9-1900.
88mmL56 APCBC velocity from 0m to 2000m changes from 780 m/s to 607 m/s. That's 2580 fps to 1991 fps, for a -23% drop in speed over 2000m.
76mmL52 APCBC goes from 2600 fps at 0m to 1910 fps with M1A1C gun and 1978 fps with M1A2 gun. Small differences, but 88L56 is slightly more accurate if one considers better gun sight and possibly smaller dispersion.
We don't have American dispersion data for their APCBC. We do have dispersion for 50mm L60 APC (very small, even smaller than 88L56),50mm APCR, and for 75mmL48 APCBC and APCR. 76.2L51.5 used by Germans has largest round to round dispersion we have ever seen for main ammo, 75L48 is not far behind.
U.S. velocity loss with range based on a commonly accepted method of estimating velocity with range called Sciacci's method, using ballistic coefficients. German data for striking velocity at range is probably based on similar estimates. It is very difficult to measure velocity accurately at 2000m.
British field test data for lead errors versus moving targets suggests that errors don't improve as number of shots increases. Leading a target is tricky stuff, you move the gun with the target as it moves and then move the gun out in front by the desired lead and quickly pull the trigger.
Following is a detailed discussion regarding potential problems with published data. We are constantly re-examining published info and our conclusions.
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Published Russian penetration data is defined in WW II German documents as DeMarre calculations against "zementen platten" using a penetration constant K, which suggests face-hardened plate. Russian data is similar to German for AP and APBC, main difference is ballistic cap on APBC slows velocity loss so penetration at range is greater.
Russian penetration data looks like test data but it probably is calculated, we have American test data for 122mm APBC versus U.S. plate at angles from 0° to 70° and it goes through alot more than 168mm at 0m and 0°, and it has unbelievably low slope effect due to flat nose. 122mm APBC slope multiplier of 1.62 versus Panther glacis at 55°, while U.S. 76mm APCBC has 2.52.
We have carefully reviewed alot of German, U.S. and British penetration range listings over a long period of time and most eventually prove to be calculations using available information. British charts even say, on occasion, that about 10% of penetration ranges in a document are based on actual field tests and rest are calculations, but report won't say which is which.
Panther and Tiger Fibel contain figures showing how far guns could penetrate enemy armor such as Matilda and T34, and it all appears to be calculated based on (incorrect) assumption that T34 and Sherman armor was same resistance as German penetration test plate.
The publishers of penetration ranges sometimes thought they represented field tests, and say they are test results based on a curve of best fit through field results, but ALOT of data out there was computed in an office and is not reliable.
Jentz presents alot of penetration range data and it appears to be based on field tests. Like when they shot all sorts of guns and ammo at PzKpfw IIIH front hull in Africa and reported the penetration ranges, this is the real thing (we have original reports, they match and also verify it is a test result).
The British often tested ammo at 30° and then used an assumed slope multiplier to convert data to 0°, which overlooked T/D ratio and presents questionable data for
0°. If 17 pounder APCBC penetrates 140mm/30° at a given range, 0° penetration might be listed at 140 x 1.25 = 175mm if 1.25 is assumed multiplier.
We have a published set of U.S. penetration data that is all based on one set of slope multipliers for all ammo and all armor thicknesses, so most of the data is suspect.
When Soviet data is presented for guns and ammo pen. range versus Tiger II in Jentz, we went through the calculations and the data seems to be real. However, Soviet pen. ranges are often based on calculations from their published data which assumes that AP and APBC penetrate same armor at same velocity, so both have same penetration at 0m: this is unlikely to be true, AP is sharp nose and APBC is flat nose (sounds like Land Before Time).
Changes in 122 flat nose penetration with velocity are also different from 122mm AP.
That German 50% hit probability by 88L56 against 2.5m x 2m target at 2000m is a calculation based on 0m range estimation error, we reproduced the analysis from original German data sheets.
Analysis suggests that 88L56 has 5% accuracy at 2000m vs. 2.5m x 2m when 25% average range estimation error is used with bell shaped distribution curve, based on trajectory and dispersion analysis.
British analysis of Panther A armor shows it to be face-hardened on lower front hull and hull side. We have original reports on this. How many books list Panther A hull side armor as face-hardened. Panther D glacis appears to have been face-hardened at first, even though it exceeded 60mm.
We play armor miniatures and have graphs that we use to resolve play. Plus the computer spreadsheet that computes everything one might want to know. We are thinking of putting the spreadsheet and supporting documentaion booklet into the public domain when we finish data collection in a month or so.
Our group is a loose collection of folks that look at things and present data and speculation. We then try to confirm the speculation.
My profession is civil engineering, licensed airport engineer in New York, and mathematical models are a hobby. Tank gunnery makes an excellent subject since it is loaded with odd twists and turns, like shatter gap.
Your game seems to be quit excellent and we enjoy the forum.
