rexford

Frederic Erk is handling European orders of the book and European orders contact Mr. Frederic Erk at curator@musee-des-blindes.intranets.com An announcement for USA, Canadian and other orders will be made on the General CM Forum shortly. I will be the contact.

The true test of equations and theories that are based on a few tank analyses is how well they compare to actual combat results. Using 85mm for Panther glacis thickness and 65mm for the nose gives better consistency with firing tests against Panther and combat reports than 80mm and 60mm. 85mm is not only 6% thicker than 80mm, it gives a higher slope effect. When 17 pounder hits 85mm and 80mm armor at 55° the armor resistances are 206mm and 221mm at 0°. A 7.2% difference that can make a difference on the battlefield and proving grounds. We have German and American firing tests against high hardness armor like the T34 carried. The Germans used 37mm and 50mm guns against very hard 45mm plate at various angles, the Americans used 37mm through 90mm ammo. An equation was prepared and is presented in the book for hits on T34 hardness armor. The predicted penetration ranges for 75L43 against T34 front hull armor compare well with the stories in Jentz. So a small sample test ends up working well when it is compared to larger scale combat situations. That is the final test and it appears to confirm the general validity of the firing test data and analysis. That is the best one can do in many WW II research cases. [ 07-05-2001: Message edited by: rexford ]

The German tests of 76.2mm Russian guns using 7.6 kg rounds were based on German made APCBC rounds, which were to German nose hardness standards. The rounds had rounded noses. These are the German made rounds that were fired by the rechambered captured Russian 76.2mm gun on the Marder. Tests with 7.6 kg projectiles are not indicative of what Russian made 76.2mm APBC flat nose ammunition would penetrate. Those tests do relate what a captured T34 would penetrate using German ammo and a rechambered gun. The Russian Battlefield and other sources indicate that Russian 76.2mm APBC weighed 6.3 and 6.5 kg.

John, what is the weight of the 76.2 rounds in those German tests. Thank you.

John, Given the limited data available to draw conclusions, the question should not have been that one needs a wealth of unobtainable data but whether there were enough different bits of data to support one figure over another. I am not uncomfortable with your question, it is the manner in which it is posed which may tend to shut down the communications. If the question is posed such that a positive answer is impossible, then that ends the discussion. Why not ask what is the total picture that favors using one or another, which leaves the door open. Refusing to go one way or the other unless unobtainable data is presented shuts all doors and locks them tight. That is my point.

[ 07-04-2001: Message edited by: rexford ]

John, I would appreciate it if you would share the German tests of 76.2mm BR-350A APBC with me and others on this board. They were at 30°? To summarize my previous posts, WW II projectile penetration did not occur on the same basis but varied according to nose hardness, nose shape, whether the ammo was solid shot or HE filler and if it had armor piercing caps. German 75mm APCBC outpenetrates U.S. 75mm APCBC at the same velocity, and both outperform Russian 76.2mm APBC at 0°. One can assume that they all penetrate according to the same equation but they don't appear to. We are not basing Panther 85mm on a few tests, but what the nations who fought the Panther found to be the case.

John, Since we only have a small picture of WW II tank combat and armor analysis, we have to take what we have and use it to extend the results to all the tanks. When someone asks for definite statistical proof that a conclusion is valid it obviously can't be found, and that tends to discredit ALL conclusions. Is that your intent, to discredit everything that is not based on analysis of at least 10% of the tank sample? Then we would have next to nothing. That is why asking for statistically valid conclusions is not a fair question because it invalidates almost everything. CM uses a single quality modifier for Panther that is not valid across the board. All Panthers did not have flawed glacis, only the glacis tended to be flawed, and the quality factor varies with the T/D ratio. Six Panthers have been analyzed and half were flawed, half were not. This suggests that half were good if we extrapolate to all the Panthers. That conclusion is statistically invalid and stuff like this in construction design would lose an engineering license quick as can be, but we're dealing with a subject with tremendous uncertainty and one has to draw conclusions based on limited data. When 17 pounder APCBC hits Panther glacis the quality is 0.95. CM is not an exact duplication of our work, and underestimates Panther resistance against 17 pounder APCBC. Now, since our work on flaws is only based on a few armor tests, should it be tossed due to small sample size? And our results on 75mm hits against 45mm high hardness? And cast armor deficiency to rolled armor? Russians assumed 85mm for Panther glacis, British do, Americans do. We do. What CM does is up to them. I'am not asking them to change anything, just pointing out that the WW II combatants thought the Panther frontal armor thickness was best described as 85mm and 65mm, based on their measurements and experience.

85mm is based on prevalent thickness measured and publicized during WW II, and my posts have indicated that oversize armor thicknesses do not appear to follow a bell curve distribution between 80mm and 85mm. They tend to be greater than 80mm, and by more than 1 or 2 millimeters. It would be nice if remaining Panthers could be measured, but this probably won't be done. Would this tend to show mostly oversize thickness Panthers since might have a theoretically higher chance to survive? No, since practically all Panther kills in Europe were penetrations of armor on side, rear or turret/mantlet. U.S. 75, 76 and 90 guns did not rack up impressive number of Panther kills through glacis penetrations, or even more than a handful. Panther penetrations on Russian front would have more glacis penetrations, and difference between 80mm and 85mm may be less important than armor quality in many or most cases.

The penetration figures for Russian APBC ammunition in our book are based on American tests using good quality armor, and yield results that are slightly below the published test results on the Russian Battlefield. However, the U.S. tests we have are for 50% success criteria and are based on ALOT of rounds fired. And the results are consistent with the British tests for 76.2mm APBC against vertical armor. Russian APBC penetrates less than German APCBC at 0° and 610 m/s due to nose hardness and nose shape. Russian APBC also follows a different penetration-vs-velocity curve than the DeMarre equation assumes, which is another reason why a DeMarre analysis of Russian APBC penetration does not work. The interesting thing is that at 610 m/s, U.S. 76.2mm APCBC outpenetrates Russian 76.2mm APBC by 90mm to 75mm at 0°. However, and this is the strange part of it, at 610 m/s Russian 76.2 APBC will penetrate a 40mm plate at 60° and U.S. 76.2 APCBC will not penetrate. The difference between a Russian flat nose round and U.S. APCBC is that the Russian round has less penetration at low angles but is exceptional at greater impact angle due to the flat nose that digs into the armor. Flat noses counter ricochet by turning the round into the armor. The U.S. tests showed this and theory supports the test results. The British report PENETRATION OF ARMOUR PLATE, and American reports, present the theory of flat nose projectiles and anticipate lower slope effects. Regarding German tests of Russian 76.2mm, one must be careful that they are not looking at test results for German made 76.2mm APCBC fired from rechambered 76.2 guns. Jentz and other sources published German penetration data for Russian 76.2 guns against German armor, and the rounds were German made. German made 76.2 rounds fired from captured 76.2 field gun and T34 76.2 weighed over 7 kg (7.6?), while T34 fired a 6.3 to 6.5 kg projectile. German rounds fired from Russian guns were at 61 Rockwell C nose hardness, Russian rounds were at 52 Rockwell C. This is in our book and was originally presented by Miles Krogfus, which strongly suggests that Russian rounds penetrate less than German under certain conditions (slope angle and impact velocity) due to nose hardness differences. See our book for American firing tests where nose hardness was varied and impact on penetration was analyzed. If one is looking at a test of Russian guns firing German made ammo they would penetrate the same as German rounds. The British and American tests of Russian APBC show that Russian ammo penetrated much less than German APCBC at 610 m/s and 0°. [ 07-04-2001: Message edited by: rexford ]

Regarding Kips' analysis of German, American, British and Russian penetration on the Der Kessel site, nose hardness figures varied widely. Averages are German at 61 Rockwell C, American at 54.5, Russian at 52, based on actual measurements taken during the war. British rounds use same DeMarre constant as U.S. ammo when we compared penetration. DeMarre cannot be used for Russian APBC since it has a flat nose and other ammo has rounded nose with armor piercing caps. And DeMarre cannot be applied to rounds with different nose hardnesses. We have actual U.S. tests of Russian APBC against American armor plate, and T34 76.2mm APBC penetrates about 91mm at 0m and 0°. WW II British tested various rounds at 610 m/s impact against vertical plate, Miles Krogfus published test results in AFV News magazine. German 75mm penetrated 103mm, U.S. 76.2mm penetrated 90mm and Russian 76.2mm penetrated 75mm. 17 pounder APCBC penetrated 107mm. All of this can be explained on basis of nose hardness, nose shape and whether a round is solid shot. 17 pounder is solid shot and outweighs the other rounds, so direct comparison cannot be made using test figures. HE cavities decrease penetration by 10% or more. U.S. tests of German ammo show that German 75mm would outpenetrate American 75mm by over 16% at same velocity and weight. British tests showed a 15.7% advantage of German 75mm over American 75mm at 610 m/s, when U.S. 76.2mm penetration in British test is used to estimate U.S. 75mm APCBC penetration at 610 m/s. If German 75mm penetrates 136mm at 0m at 750 m/s, U.S. 75mm APCBC in CM should penetrate about 89mm at 0m and 619 m/s after nose hardness differences are considered, which is consistent with TM9-1907. Based on British test data, U.S. 75mm APCBC would penetrate 89mm at 610 m/s, and muzzle velocity at 0m was 619 m/s. CM has about 100mm penetration for Sherman 75mm at 0m, which appears to be about 11% too high. Our book goes into penetration data analysis considering nose hardness and the impact of armor piercing caps and solid shot-vs-HE cavity rounds, and presents data that is consistent with actual firing tests. [ 07-04-2001: Message edited by: rexford ] [ 07-04-2001: Message edited by: rexford ]

Good point about sloped armor being a way to make a fast tank lighter. That may have been what was behind the first major use of sloped armor.

Since we have looked at armor thickness variations from design specs and changes from other published figures for over 15 years, we considered that the variations we saw might have been the upper range of the 0% to +5% allowable factory variation. 85mm is 6.3% over the 80mm spec, and 65mm is 30% over the 50mm spec, so it was obvious that we were not seeing normal variations, we were looking at oversize armor as a way of life. And some SU 100 glacis thicknesses are almost 10% below the 75mm spec. Instead of seeing many 80mm and 81mm results and a few 85mm, it seemed like everyone used 85mm for Panther glacis thickness in most cases. Knowing how careful the British were during the war about things, why would they use 85mm for firing tests and calculations when the average was 82.5mm? For the Tiger armor, the British use 102mm and 82mm and 62mm even though German sources have 100 and 80 and 60. Over and under size armor thicknesses are discussed in our book along with presentation of cases where the design specs and actual measurements did not match up and in some cases exceeded +5%. Robert measured tank armor thicknesses at Aberdeen and other locations (including tanks in front ot VFW and Legion Halls that he would drive by and then stop), and he carefully tabulated actual thicknesses measured during Allied and Russian analysis of captured German vehicles. The Ferdinand/Elefant armor measured over 5% thicker than spec for several armor pieces. Robert Livingston wrote a section in the Introduction to our book entitled ARMOR HISTORY, where armor hardness and quality is discussed as a function of thickness and year, as well as examples of armor thicknesses that have significant variations from the spec. Jeff's response to an earlier post was on the mark, during wartime bigger may be better when less stands a chance of being rejected. Our book is based on acceptance of the following assumptions: 1. Panther front hull armor is 5mm thicker than the design spec, for penetration range calculation purposes. 2. T34 armor is high hardness and conforms to the resistance-vs-T/D ratio trend noted during American and German firing tests (which assumes the same average armor quality as occurred during those tests). 3. Panther glacis quality varies widely, but about half the tanks have good quality plate (and half have lowered resistance which can vary from tank to tank). 4. Other than a 2mm increase above specs for Tiger I and plus 5mm for PzKpfw IVH front hull (85 instead of 80), we didn't see any trend for other tanks or armor areas that implied significant oversize armor. So 30mm on side of PkPfw III and IV is listed as 30mm, and 50mm on front of PzKpfw III and IV tanks is listed as 50mm. 5. If readers of the book or other folks wish to use 80mm and 60mm for Panther front hull, that is their right, we choose to use the commonly accepted 85mm and 65mm which is supported by firing test measurements. We wish someone would go out and measure the front hull armor on all of the Panthers lying and sitting around in Europe, in Museums and out doors. Without that we look at what was measured and the figures most people used during the war, and we accepted that as reasonable. P.S. One other little tidbit that was noted to me by a poster was that German armor had to pass ballistic tests, and an 85mm plate stood a better chance of passing than 80mm. While materials were in short supply, getting out Panthers without mass rejection may have been an important consideration. Oddly enough, there is little published evidence that T34 armor varied significantly from 45mm design thickness. A few references to 47mm thickness is about it. However, the 45mm side armor on SU 100 did not measure 45mm, and varied by some really large amounts. Maybe T34 armor specs allowed less variation due to speed and material conservation consideration on a mass produced vehicle, while SU 100 was a relativeley limited run specialty vehicle, late in the war, where tight controls were relaxed (45mm plus or minus 15%). The 45mm bow armor on one SU 100 measured over 55mm thickness, which exceeds 20% overage. Our book may be one of the first publications to look at actual measured thicknesses instead of using design specs, and to go with alternative thicknesses that looked reasonable. Robert Livingston did a great job summarizing armor history in the book Introduction, and provided examples of major variations from design spec thicknesses that appear to be the rule rather than the exception. The armor history section is 7 pages long and covers American, British, German, Russian and Italian armor to varying levels of detail. We did not find any significant examples where Italian or British armor varied widely from design thickness, but most of the reports available to us that could be used to compare armor measurements to design thickness were on German, American and Russian vehicles. American armor actually did not have a limit for oversize thickness, and Robert provided some examples where the measured thickness was more than 10% greater than the spec.

John, You're asking a question that is impossible to answer, and it may be an unfair question because the answer you ask for cannot be found. If one looks at a number of Panthers and most have 85mm, and the Russians, British and Americans use 85mm in most of their paper studies based on measurements, the data suggests that 85mm is it. Since we will usually have incomplete information on many or most WW II issues, all we can use is identified trends that cannot be proved statistically but seem correct. That is the best we can do. It is like asking for battlefield "proof" beyond a few anecdotes that the CM hit probabilities are too low for experienced and elite crews. There is no way to disprove the probabilities. Every time someone asks for "proof" beyond a few tank examinations it diverts attention from the basic character of WW II research, where we are all drawing conclusions from incomplete data on the basis of what sounds reasonable. With regard to T34 armor quality, that is also a non-issue. Americans and British looked at a few samples (1942 T34 and 1945 T34/85), and they were high hardness with irregular quality. Germans looked at a whole lot more and they were all high hardness. As I noted previously, armor quality is a relatively insignificant issue with T34 high hardness armor cause 45mm won't resist 75mm hits very well regardless of quality. Poor quality high hardness only makes poor T34 resistance even poorer. People have the right to ask for proof, just realize that this is not a tightly controlled experiment where everything is available and that we are using different levels of "proof". If the Russians, British and Americans use 85mm thickness for Panther glacis and 65mm for the nose, and measurements support oversize armor, that is good enough for me. They certainly don't appear to be repeating the 80mm thickness the Germans used.

Russian Battlefield has data on tank losses due to various size German guns, which offers unusual detail. Interesting data is % by 88 guns. Will try to identify exact location where the Russian tank loss % are contained.

85mm thick plates on Panther glacis and PzKpfw IVH front hull. 65mm thick plate on Panther nose, sometimes up to 75mm. We don't know what others found or used, but we went through firing test data, what was actually measured by others or Livingston, and what Russia, Britain and U.S. used in their calculations. We saw a trend towards more than 80mm thickness on Panther glacis plate and more than 60mm thickness on Panther nose plate, and it seemed that most studies assumed the greater thickness. Just about every Russian analysis of Panther armor on The Russian Battlefield says 85mm thickness Panther glacis. Look through John Salt site for the many analyses of penetration ranges against Panther glacis armor, how many assume 80mm armor thickness? Very few use 80mm. Since 85mm at 55° resists penetration like a much thicker vertical plate due to slope effects, when I refer to 85mm Panther glacis it is plate thickness. Tiger II example was just a shortcut that I neglected to explain. The book lays out all the assumptions and math so readers won't be confused.

Several posters on other sites have speculated that German armor was oversize so it would pass inspection. If the tank armor was a few millimeters short the whole output might be rejected, so make it a few mm too thick on average and make sure it passes. A StuH welded mantlet that was supposed to be 50mm thick actually measured out at 65mm! Robert Livingston measured several SU 100 glacis plates that were supposed to be 75mm thick, and they were all less than 75mm and some were under 70mm. We used figures that were accepted in many sources. Russians, Americans, British all use 85mm for Panther glacis calculations during many, if not most, of their analysis. And 65mm for Panther nose. Germans said 80mm and 60mm for Panther front hull, most penetration studies use 85 and 65.

PzKpfw IVH generally used one single plate of about 85mm thickness. PzKfw IVG started out at 50mm front and later added 30mm bolted or welded to 50mm. I am not sure about the bolting cause most pictures seemed to show welds, but it has been a long time since I looked. When two face-hardened plates are bolted or welded together, the total may be more resistance than the sum of the thicknesses. When PzKpfw IIIH put 32mm face-hardened on top of 30mm face-hardened, the resultant resistance of the two plates was 69mm of face-hardened armor prior to slope effects. This result is based on analysis of firing tests in North Africa using 37mm, 40mm, 57mm and 75mm ammunition (AP and APCBC). The usual assumption is that two plates bolted or welded together are less resistance than a single plate with same thickness, many British test results show layered armor can be more resistant. This is in our book along with spaced armor and edge effects.

PzKpfw IVG had 30mm on top of 50mm, both face-hardened. Only the PzKpfw III carried spaced armor. IVH had 80mm design thickness but German armor tended to be oversize, Panther glacis measures 85mm most of time, Tiger side armor is usually a few mm over 80mm, many British analyses use 85mm for IVH front. Panther nose is 60mm design, British measurements put it at 65 to 75mm. Isigny test report on Mycenius site included an actual Panther nose armor measurement, it was 67mm. 189 for Tiger II turret front includes angle, 185mm at 10° slope equals 189 at 0° against 90mm APBC. We use 85mm for Panther glacis and PzKpfw IVH front hull areas (driver plate and upper nose). 82mm for Tiger side and 102mm for Tiger front. Our book has a discussion of armor design specs versus what was actually measured, which includes measurements by Robert Livingston at Aberdeen Proving Grounds and other locations. Robert also measured angles, and we have a neat drawing of the M4A1 upper hull front with a detailed layout of angles and thicknesses. He found an M4A1 at a Legion Post on his way back from Pennsylvania, and stopped to measure angles. M4A1 upper hull front was one piece cast, which was 13% less resistance than rolled armor when 2" thickness hit by 75mm rounds. And American cast armor built prior to late 1943 tended to be flawed, so cut the resistance some more. And M4A1 is less than 56° that you find on rolled armor glacis Shermans, so decrease resistance some more. And M4A1 has those big driver and MG hoods at low angles. Zaloga wrote in one of his books that American tankers refused to use M4A1 when rolled glacis Shermans were available. Is it any wonder? The advantage of the M4A1 hull front is that the outside areas are sloped vertically and to the side, so hit the outside areas and ricochets will probably occur due to effective resistance. We looked at 76mm hits bouncing off Panther side armor many times. The comment about angled hits is on the mark. Armor is sloped at 40° vertically and say it is hit with side angle of 55° (35° from front hull facing). The resultant angle is 64° and armor resists like 120mm at vertical. 76mm APCBC penetration at 800 yards is 112mm, so rounds could all bounce off. 37mm APCBC penetration against face-hardened and homogeneous follows: 100m 78mm homogeneous, 73mm face-hardened 500m 69mm homogeneous, 67mm face-hardened 1000m 59mm homogeneous, 57mm face-hardened There is British data which shows that 6 pounder APCBC shatter failed against face-hardened armor that is should have been able to penetrate. The larger difference between 37mm APCBC penetration against face-hardened and homogeneous at 100m could be due to nose failure at higher velocities.

WW II German ballistic analysis of HE fire ground patterns due to dispersion show that slow rounds are more accurate against point targets on the ground. My review of the mechanics verified the German findings. If a 75L42 and an 88L56 are firing HE at a ground point target, the middle of a group of soldiers at 700m, and both rounds have the same vertical scatter about the average flight path, the 75L24 HE will land closer the aim point more often. Will 75L24 HE be more lethal than 88L56 HE if both land the same distance away? If 75mm fires Sprgr. Patr. KwK(34) and 88 fires any HE round available, 75mm HE will have a higher HE filler % of total weight, and probably will have thinner walls, and should put out more average fragments per unit area. 75mm will land at a higher descent angle than 88mm, but both are landing at relatively shallow angles. My analysis stopped at which HE lands closer to aim point and which puts out more fragments per unit area (on average). If there are graphs that dispute this post them on this site for review. Several folks posted data and scans that supported the German ballistic analysis of HE ground dispersion pattern (where shell lands, NOT fragment pattern).

One of the interesting aspects of German armor is that many tanks have face-hardened armor and some are limited to homogeneous armor, so one penetration figure does not cover both types. Sherman 75mm APCBC penetrates 81mm homogeneous and 95mm face-hardened at 500m, based on TM9-1907. PzKpfw IVH has face-hardened 85mm front hull, Tiger has 82mm homogeneous side armor. Panther has 40mm face-hardened side hull on A and D models, StuG III probably has 30mm homogeneous side armor while PzKpfw IVH has 30mm face-hardened. Tiger II with early turret has 100mm face-hardened mantlet and one side of turret is face-hardened, Tiger I is completely homogeneous armor. This issue will come up big time in CM2, since PzKpfw III and IV use lots of face-hardened armor (most of the front armor), and Panther D not only has face-hardened side hull armor but the first 850 Panthers have face-hardened glacis plates. And Russian data for face-hardened penetration does not appear to be obtainable, based on our searches. Russian ammo did not use armor piercing caps, so it would be less effective against face-hardened armor. The theory is that the Germans viewed Russia as the major threat, so armored their vehicles to defeat rounds without armor piercing caps. Face-hardened armor would also be good in North Africa where the British didn't recognize that armor was in use until way into 1942. But Allied use of armor piercing caps left face-hardened armor in a weaker position relative to homogeneous armor. As much as I hate to admit it, putting face-hardened armor on PzKpfw IVH front hull made the darn thing even more vulnerable to Sherman 75mm hits in France and Germany, and Panther side hull on A and D models is easier to beat with those low velocity Sherman hits due to the armor used.

IS-3 turret front was 220mm minimum, and mantlet was 205mm. Problem with IS-3 was glacis, and hitting the small mantlet area on a rounded spherical turret. Tiger II turret front is 189mm, IS-3 is not only thicker and spherical but is a smaller turret. U.S. published data for 90mm T33 APBC seems questionable, it would have to have LOWER nose hardness than normal American ammo to penetrate 117mm at 30° at 1000m. It had higher hardness, so something seems wrong.

If T33 APBC has 220mm penetration at 1000m, it also goes through Tiger II turret front well beyond that range. The main problem with the penetration estimates is that sources list 90mm T33 penetration at 1000 yards as 117mm vs 30° armor, which is the same as 153mm at 0°, well below 220mm. With less than 153mm penetration at 1000m, T33 would never be expected to pemnetrate Panther glacis.

90mm T33 APBC as fired by Pershing may be the second most penetrating steel round of WW II, next to 128mm and ahead of 88L71 APCBC, 122mm APBC and 100mm APBC. Hunnicutt states in PERSHING that 90mm T33 APBC was reheat treated M77 AP with ballistic cap added, and somewhere it lists a 1000m penetration range against Panther glacis. If U.S. 75mm solid shot AP penetrates 114mm at 2030 fps, DeMarre estimate for 90mm T33 would penetrate 220mm at 0m with same nose hardness (54.5 Rockwell C). With reheating of T33 to obtain German nose hardness level (61 Rockwell C), 90mm T33 APBC could penetrate 260mm at 0m and 220mm at 1000m, giving round more penetration at all ranges than 88L71 APCBC. That 220mm penetration estimate at 1000m is interesting because it equals the resistance of a 0.85 quality Panther glacis to 90mm APBC hits, which suggests that 90mm T33 could penetrate 220mm at 1000m. Why would 90mm T33 APBC outpenetrate 88L71 at 1000m despite lower muzzle velocity, 2800 fps vs 3280 fps? T33 is solid shot and does not have armor piercing cap, both of which are advantages over 88L71 APCBC-HE. The HE cavity in ammo weakens the projectile and decreases the penetration by at least 10% to 12%, and armor piercing caps decrease homogeneous penetration by 12% or more, so 88L71 at 3280 fps penetrates about 235mm at 0m (T33 does 260mm). Based on 1000m penetration range and penetration estimates with increased nose hardness, U.S. 90mm T33 appears to be one of the premier Panther killing rounds of WW II, maybe even better than 90mm HVAP. 90mm HVAP was listed as having less than a 500m penetration range against Panther glacis. HVAP slope effect at 55° is 3.45, giving unflawed Panther glacis a resistance of 293mm at 0°. 90 HVAP penetrates 293mm at 280m, which means the Panther which was penetrated by 90 HVAP at 450m had 0.96 quality (that variable Panther glacis armor quality pops up again).

T34 need for speed helps keep PzKpfw III with 50mm L60 gun an important part of the panzer picture. 50mm L60 tank gun and Pak penetrate 45mm at 40° side armor on T34 to 1250m with no side angle to shot. If T34 goes to 60mm at 40° side hull, penetration range for 50L60 drops to 500m, and less if shot is taken with at an angle to side plate. But 60mm side hull armor slows down T34, and just as importantly reduces the cross country distance the tank can move without refueling. Russians know that T34 side armor is very vulnerable and causes many losses that might be reduced by thickening armor. But speed and cross-country/road range are more important. Adding a cupola to reduce losses through side vision improvements adds weight but not so much, and cupola has less impact on maneuverability than those 15mm to 20mm armor add-ons to glacis that cause all sorts of problems and only reduce penetration ranges by a little bit. Placed in perspective, it seems likely that T34 design centered around certain objectives and radical changes were not allowed. T34/85 keeps side armor the same while they add bigger gun and heavier turret, cause speed and range are crucial. T34/85 has cupola to help when enemy is on sides.