rexford

During late 1943, Aberdeen Proving Grounds conducted firing tests against three captured Tigers. The results showed that: 1. Tiger armor plate with 60mm, 80mm and 100mm design specified thickness measured an average of 62mm, 82mm and 104mm. 2. Tiger armor was, on average, equal in resistance to American penetration test plate 3. The standard deviation of the Tiger armor resistance ratio to U.S. plate quality was 8%, which means that: a. if penetration is 16% above theoretical armor resistance based on thickness and slope effects, 98% penetration probability b. if penetration is 8% above armor resistance 84% success rate c. if penetration equals resistance, 50% of hits defeat armor d. when penetration is 8% below armor resistance, 16% of hits will still manage to penetrate fully e. if penetration is 16% below armor resistance, expect about 2% to succeed The 8% standard deviation is roughly equal to what analysis of Russian penetration data indicated, and is similar to modern firing tests for WW II type projectiles (steel with pointed noses). The finding that Tiger armor is roughly equal in resistance to U.S. penetration test plate confirms the finding in our book, WW II BALLISTICS: Armor and Gunnery. Tiger armor also appears to equal British test plate in average penetration resistance.

The velocity versus angle curve for shatter failure of tungsten ammunition predicted failure cases for 17 pounder APDS where the round had more than sufficient penetration to defeat target armor, but failed. Since the original posts, additional research using data from Thomas Jentz' Germany's Tiger Tanks, Tiger I and II: Combat Tactics, has indicated that 6 pdr APDS succeeded at velocities where the tungsten shatter theory predicted failures. An additional contradictory case has been discovered with 90mm HVAP. The penetration curves following Page 17 in WW II BALLISTICS: Armor and Gunnery, by L. Bird and R. Livingston, were revised to depict the shatter failure velocity vs angle curve which appeared to apply to 17 pdr APDS. Two 90mm HVAP penetrations occur at velocities slightly above the shatter line, which theoretically would result in failures. While 17 pounder APDS failures and successes for cases with overpenetration of the target are in complete agreement with the previous theory, 6 pdr APDS and 90mm HVAP firing tests are not consistent with the firing test data and theory. So one can either assume that there is something about 17 pdr APDS that has it follow a firing test curve for shatter failure while other tungsten rounds do not, or one can take the approach that the 17 pdr APDS agreement with theory is a coincidence and the theory would be be disproved if more firing tests were made at velocities within the shatter fail zone.

We have a German test report dated 1942 where 50mm AP penetrated 47mm T34 type armor at 100m and 60° slope. From the 90mm APBC tests and the 50mm AP performance against T34 type armor, it appears that the high hardness of T34 armor works against the tank, and the brittle plate makes a T34 much more vulnerable. If T34 used 250 Brinell Hardness armor, which takes some care to produce properly, the 45mm at 60° front hull would have the same penetration resistance as a 122mm thick vertical plate. This will stop PzKpfw IVH hits at 500m. But T34 used 400+ Brinell high hardness armor, and the 45mm at 60° resistance drops to a 93mm vertical plate due to brittle behavior. A PzKpfw IV will have no trouble with this armor at 1000m at any angle. The German test results that we have show 37mm AP penetrating 54mm of high hardness armor like the T34 carried at 100m. Like the Sherman which suffers an 85% quality multiplier in CMBO, T34 in CMBB may have a 76% quality factor against 75mm hits due to the frailities of very high hardness. ------------------------------------- American APBC is uncapped pointed nose shot with a ballistic cap, Russian APBC is a flat nose round with a ballistic cap. When the ballistic limit falls with increasing hardness, the results are strongly suggesting that the armor brittleness is causing premature failure. High hardness armor is crystalline in structure, and is like a house of cards in that the structure is dependent upon a weird set up where molecular pieces are hanging by their edges. Once a sharp impact is made and one of the edges lets go, the armor fails suddenly and in a big way. Softer armor is much more giving, and will bend alot and absorb tons more energy before the round gets through. Soft armor stops the hit by making the projectile push its way through the thickness. Hard armor defeats hits by causing the round to absorb its own energy through nose and body damage, since hard armor cannot deflect much without falling apart.

The U.S. tests against high hardness armor were conducted with "decent" quality armor: defeated armor in tests that described armor failure modes did not suggest poor armor characteristics. The estimates in our book for high hardness armor resistance are based on equations drawn from U.S. test data. When our penetration range estimates for T34 against 75L43 APCBC are compared with actual combat reports in Thomas Jentz' Panzertruppen books, the estimates present reasonable agreement with reports. This was one of the factors we considered when we assumed that U.S. high hardness armor was similar to Russian. Reports on T34 armor also show undesirable elements as well. During 1942, the Germans reproduced T34 armor with the same composition and heat treatment, and fired 37mm and 50mm tank guns against the plate at various angles (100m range). High hardness armor is going to be less resistant than 250 Brinell plate when the projectile diameter exceeds the armor thickness, due to low impact resistance and brittle structure (high hardness requires crystalline structure which is brittle and subject to rapid failure, 250 Brinell will be fibrous and ductile when carefully mixed and produced). The German 50mm AP round fully penetrated 47.2mm at 60.5 degrees, and 42.1mm at 65 degrees, during the tests. Partial penetrations were obtained against 47.7mm at 59° and 47.1mm at 59.5°. The abovementioned results suggest a 1-in-3 complete penetration ratio when 50mm AP struck 47.3mm at about 60°, which requires a penetration/armor resistance ratio of about 0.98. If 47.3mm of 240 Brinell plate at 60° is estimated as equivalent to 123mm at 0° on 50mm AP hits, then the penetration/armor resistance ratio is only 0.80. However, if 47.3mm of high hardness armor resists with 83% of the resistance of 240 Brinell armor when it is hit by 50mm rounds, then the 1-in-3 penetration ratio is supported. WW II BALLISTICS: Armor and Gunnery, by L. Bird and R. Livingston, estimates that 45mm high hardness plate resists with 83% of 240 Brinell armor against 50mm hits. Granted we are talking about a handful of firing test results, but the German tests are consistent with the equations prepared using U.S. high hardness armor, and are reasonably consistent with reported penetration ranges in Jentz' works. Interestingly enough, when 50mm AP hit 40.9mm high hardness plates at 40°, two of five hits failed even though the armor resistance was well below the penetration of 50mm AP at 100m. 40.9mm at 40° should resist 50mm AP like 63mm, and less when high hardness deficiencies are considered. It appears that 50mm AP rounds were shatter failing against the 40.9mm plates even though they possessed more than enough penetration to defeat the armor.

We recently received excerpts from a WW II Aberdeen Proving Grounds reports on the penetration of 90mm T33 APBC rounds as a function of armor thickness, angle and brinell hardness. The Army Protection Limit varies with armor hardness in the following manner at angles from 60° and 65° against 3" plate: 60° Impact 2629 fps against 280 Brinell, 2554 fps against 360 Brinell and 2348 fps against 400 Brinell 65° Impact 3026 fps against 280 Brinell, 2948 fps against 300 Brinell and 2870 fps against 320 Brinell What does this mean for WW II penetration range estimates against tanks with high hardness armor, like the T34, T34/85, SU 85 and SU 100? When 90mm T33 APBC strikes 3" armor the thickness/diameter ratio (T/D) is 0.85, and 400 Brinell Hardness armor at 60° resists with about 85% of the 0° resistance of 280 Brinell plate((2348 fps/2629 fps) raised to 1.4 power). Since penetration tests are conducted against armor with about the same resistance as 280 Brinell plate, this means that 400 Brinell armor is going to lose substantial resistance when the T/D ratio is 0.85 or less. When 45mm high hardness armor (400 Brinell) is hit at a 60° angle by 75m German rounds, the T/D ratio is 0.60 (45mm/75mm) and the armor would be expected to resist with less than 85% of the resistance offered by 280 Brinell plate. Based on our research (which is presented in WW II BALLISTICS: Armor and Gunnery, by L. Bird and R. Livingston), 45mm armor at 400 Brinell would resist like 34mm of 280 Brinell plate when it is hit by 75mm rounds (slope effects based on the actual 45mm thickness). ----------------------------------------------- The 90mm T33 tests at 70° showed that a 2" plate at 280 Brinell presented 86% of the resistance offered by 3" at 360 or 400 Brinell plate.

If the British contingent was on ambush duty it is possible that they had scoped out the terrain and knew the ranges to various landmarks or trails. This would greatly improve Firefly accuracy by having a close estimate of possible target ranges. Under those conditions, even a moving Tiger might be hit quickly, especially if they were moving at a constant speed and in one direction, track for a while and hit the last tank. Then, knowing the target speed and lead to use, target the next tank, and so on. Past threads have beat to death the story of the M18 commander who spotted moving panzers at 2000 meters and hit them, one after the other, with single shots. If an M18 can do it at 2000 meters, a Firefly at 700-800 meters would certainly be just as able. The key to it all is keeping one's nerve about them and following training procedures. If they knew Wittmann was there it may have been enough to jiggle their nerves and lead to bad shots and worse decisions.

I agree with Tom's post, the APDS reference should have been APCBC, which was very accurate in terms of flat trajectory and low dispersion. There is little written about the 75mm armed Shermans in the Wittmann post on the Feldgrau site, they may have fired APCBC at the Tiger sides in hopes of drawing some return fire that otherwise would have gone for the Firefly. In terms of sighting a Firefly, Tom has sent me descriptons of 17 pounder APCBC muzzle flash in the past that noted a horrendous blast, the commander and gunner almost needed goggles to shield their eyes. Firefly muzzle blast and smoke probably would give away the fact that one was being fired at by a 17 pounder and not the puny 75L40. Hitting a target in the woods based on a muzzle blast target (no sight of tank) is not easy, the smoke moves and the blast radius is not small. Correcting for high or low rounds may also be difficult. If some of the Tigers were firing at 75mm Shermans it is possible that a Firefly could knock out several Tigers in succession. At 700m or 800m, there is a small chance that 75mm Sherman APCBC will penetrate 82mm armor unless the side angle is above 10°.

During Isigny tests (August 1944 in France) with 17 pounder APDS, 3 shots out of 7 at 800 yards failed to hit a Panther front target aspect, and while the shots were aimed at the glacis only one of four hits struck the glacis. At 800 yards, APDS aims at and hits glacis once in seven shots (1-in-7) At 700 yards, APDS hits glacis 2-in-7 tries At 600 yards, APDS hits glacis 3-in-4 tries At 400 yards, APDS hits glacis 8-in-11 shots At 300 yards, APDS hits glacis 4-in-8 shots At 200 yards, APDS hits glacis 3-in-5 shots All told 17 pounder APDS aims at glacis 42 times and hits 21, for 50% 17 pounder APCBC aims at glacis and hits 9-in-9 shots (100%) 76mm HVAP aims at and hits glacis 14-in-18 shots (78%) 17 pounder APCBC aims at Panther nose (small target partially obscured by ground folds) and hits 4-in-6 (67%) 76mm HVAP aims at and hits Panther nose on 4-in-6 (67%) The 17 pounder guns were fired by two superior British enlisted gunners, the U.S. 76mm by two officers with considerable test firing experience. On July 10, 1944, First U.S. Army tested 17 pounder APDS at Balleroy and obtained two penetrations of the Panther glacis on two hits at 700 yards. This result is contrary to the predictions for tungsten round shatter and also suggests much better penetration performance than obtained at Isigny. Lorrin

The following is a technical discussion of how much faith can be placed in the tungsten ammo shatter failure predictions. Don't mortgage the house and bet the money on the theory being 100% correct. ----------------------------------------------- The presented theory on tungsten shatter gap is supported by firing test data against Tiger and Panther, 2 of 17 hits by 17 pounder APDS on Panther glacis at 200 to 800 yards succeed at Isigny, France (8/43) even though most should have succeeded. See page 103 in the book, WW II BALLISTICS: Armor and Gunnery, by L. Bird and R. Livingston, for identification of 17 pdr APDS hits on Tiger that fail despite abundant penetration capability. U.S. firing tests during WW II showed that steel was not an adequate material for high velocity HVAP ammo because it tended to shatter at velocities approaching and exceeding 3500 fps, even on 0° hits. Tungsten was chosen for small, high speed carrier based projectiles because it had the ability to hold together at velocities in the 3300 to 4000 fps range. But tungsten will shatter on 0° hits when the impact forces become too high. We did some additional research on 17 pounder APDS against the Panthers at Isigny. The armor thickness might be assumed to be 82.5mm and the actual glacis impact angle was about 57.3° due to ground slope. The armor would present 252mm vertical equivalent resistance. The following table presents "penetration/armor resistance" ratio's at the Isigny ranges, estimated penetration probability and actual results (range in yards, assumed standard deviation for penetration probability is 4%): RANGE..PEN/ARMOR RATIO..PEN.%..ACTUAL PEN.RATIO 200....1.08.............98%.....1-in-3 300....1.06.............94%.....0-in-3 400....1.04.............84%.....1-in-6 600....1.008............58%.....0-in-2 700....0.988............38%.....0-in-2 800....0.972............24%.....0-in-1 The theory predicts all failures beyond 117m till 920m. At Isigny, minimum range for shatter failure appears to be about 200m (ranges in table are in yards), and even then one success occurs at 400 yards against a good quality Panther glacis. The theory does not hold as well as it did in Tiger case, where all hits within estimated velocity range for failure failed, and hits above the range succeeded. What the Panther analysis presented above suggests is that the shatter range for tungsten ammo may not be an "all or nothing" situation, but reduces the penetration probability from an average of 90% over the 200-400 yard interval to 17%. The effect of projectile yaw is another consideration, since WW II APDS accuracy was uneven and could be due to uneven shed of the sabot or unbalanced placement of the core in the round. Were the APDS failures against Tiger and Panther due to a combination of shatter tendency at higher velocities and striking armor at odd flight angles (nose and tail of projectile were not aligned along the flight path)? The APDS rounds fired at the Isigny Panther were very inaccurate, and would entirely miss the Panther on occasion. A similar situation occurred when U.S. forces fired APDS from a 57mm anti-tank gun at captured Panthers, an inability to hit the target was noted. The above discussion suggests that the tungsten shatter theory be applied cautiously and with full recognition of the fact that it might fall on its face when APDS performs in proper fashion (goes where it is aimed).

The interesting aspect of the combat in which Wittmann's Tiger was destroyed is the fact that several Tigers appear to have been killed by a single Firefly that fired first and caught the enemy with a flank ambush at about 800 yards. Also note that the Sherman 75mm gun is considered useless against Tiger side armor at 800 yards. The oddest fact is the British tanker who was dazed when an 88mm round struck the half open turret hatch, which closed and hit a tanker in the head.

Check out the following site address for a very good discussion of the combat in which Michael Wittmann's Tiger was destroyed: http://www.feldgrau.net/forum.html The discussion on Michael Wittmann is down the page. The descriptions of shots fired and missed, and the tactical issues involved (absence of any recon regarding the woods where the British were hiding, even though many Tiger crewman had concerns), touch on many important armor issues. [ 11-03-2001: Message edited by: rexford ]</p>

Past posts and threads have discussed the degree to which armor varies in resistance, and whether a single plate could have different resistance based on where one hit it, or the impact angle. The following lengthy and detailed analysis looks at the test results when the British fired 6 pdr AP at six plates which differed in thickness. --------------------------------------------- The report covering British tests of German 75mm and 88mm APCBC against oblique armor included tests with 6 pounder AP at various angles. By comparing the 6 pounder AP results to estimates from the British National Physical Laboratory equation we can gain some insights into the penetration variability of British armor plate and shot during those tests. 1. When 6 pdr AP struck 56.8mm at 40°, the actual velocity for 50% success was 1939 fps and the predicted was 2147. 2. Against 61.5mm at 40°, actual velocity is 2395 and predicted is 2307 3. Versus 65.3mm at 40°, actual is 2341 and predicted is 2434 4. Attacking 75.9mm at 30°, actual is 2113 and predicted is 2225 5. Impacting against 75.9mm at 40°, actual is 2800 and predicted is 2790 6. Hitting 80.8mm at 30°, actual is 2373 and predicted is 2342 Following is analysis of variation in terms of 0 degree penetration variations using a DeMarre estimate (penetration difference proportional to velocity ratio raised to 1.428 power): 1. -13.5% below predicted resistance..56.8mm at 40 degrees 2. +5.5% above predicted resistance...61.5mm at 40 degrees 3. -5.4% below predicted resistance...65.3mm at 40 degrees 4. -7.1% below predicted resistance...75.9mm at 30 degrees 5. +0.5% above predicted resistance...75.9mm at 40 degrees 6. +1.9% above predicted resistance...80.8mm at 30 degrees The average value of the absolute variation is 5.7%, and the standard deviation around zero variation is about 5.5% (67% within 5.5% variation, 83% within 7.1%). During U.S. tests with 37mm AP, the standard deviation was about 4%, so the British tests are somewhat consistent. The interesting aspect of the data analysis is that when 6 pounder AP hits 75.9mm at 30 degrees the armor resistance appears to be -7.1% deficient, but when the same armor is hit at 40 degrees the resistance is 0.5% above expectations. The inconsistencies in British armor resistance with angle changes continue when 50 degree hits are examined. 56.8mm plate was -13.5% deficient when struck at 40 degrees compared to 65.3mm plate being -5.4% deficient at same angle. At 50 degrees slope, 56.8mm plate has a higher slope multiplier than 65.3mm by 2.01 to 1.96, which becomes even more significant when the difference in T/D ratio is examined (1.00 for 56.8mm, 1.15 for 65.3mm). When 65.3mm is hit at 50 degrees, the slope multiplier is significantly less than for 56.8mm, which suggests a turnaround from the 40 degree case. The reason for the unusual results with the same plate may be due to varying ballistic characteristics as hits strike different locations, or major projectile changes. When 6 pounder APCBC attacked 65.3mm at 40 degrees, the actual resistance was -10.8% below expected, suggesting that 65.3mm plate was deficient on all hits during test. Reference: British report No. M.69144/4 No.1, German 75mm and 88mm APCBC Ammunition at Oblique Angle, currently held by British Public Records Office as WO 194/749 ------------------------------------------------ Could a welded hull Sherman have different resistance depending on where it was hit? Yes, because the glacis was made up of many pieces, as many as eight welded together, and some could be good, some bad, some inbetween. The welded hull Sherman also tended to mix rolled and cast pieces on the glacis, where 2" cast is appreciably less resistant to 75mm and 88 hits. Could a Panther glacis have areas that were bad and some that were good? Depends on how extensive the heat treatment problem areas are. When 2" cast armor went bad, the entire piece would usually have a crystalline structure and be very brittle. It is possible that weak areas could be localized in nature and not appreciably influence hits on better armor spots. U.S. tests on armor resistance decreases due to bad areas found the weakness causing factors could be restricted to small or large areas, which would result in a variety of results depending upon where on hit.

It is always good to keep checking results when they look odd to others. Thanks for continuing to bring up the 15° shatter results. The critical shatter velocity at 15° is 3528 fps, and the max velocity for shatter failure appears to be 10% higher, or 3881 fps. 17 pounder APDS velocity is 3528 fps at 950m, and is 3881 fps at 150m, based on our estimates. The 10° shatter velocity range is associated with 3792 fps to 4171 fps, which covers from 0m through 350m. 20° shatter occurs at 3472 through 3819 fps, which corresponds to the 300m to 1100m range interval.

If the posted table is what occurred on the battlefield, 17 pdr APDS would not penetrate the Panther glacis or nose on more than an occasional basis at 300m to 1100m. And the Tiger 25° nose armor would beat back APDS hits at 500-1300m. The Tiger driver plate (10°) could survive 17 pdr APDS at 0-300m. 6 pdr APDS would fail against Tiger front armor at: 350-850m against 25° nose 0-250m against 10° driver plate The curves are not symmetrical so the 15° results do not match up with higher angle stats.

I actually did wake up early one morning and saw that I must convert the velocity and angle data to a failure range interval as a function of angle. Luckily I sleep with a slide rule by my bed, mostly for cases where the calculator batteries run dry but it works so quiet and well. So I was able to work through the basics of my post without those noisy calculator clicking keys that may wake the others. And no, I do not wear a slide rule on my belt. Having the rule by my bed, in case of an emergency or wonderful insight that demands instant action, is more than enough security for me.

The British report, EFFECT OF IMPACT AND VELOCITY, listed the results of APDS testing for shatter velocity, which was found to vary with angle. Firing test data at Isigny, France (found on Mycenius site) and in Thomas Jentz' books for 17 pounder APDS against Panther and Tiger armor resulted in the following conclusions: 1. tests against Tiger 82mm and 102mm armor exactly followed the shatter failure limits set in the EFFECT OF IMPACT AND VELOCITY report 2. while the British report predicted that all hits on the 57° Panther glacis would fail from 150 to 950 meters, 2 of 17 fair hits penetrated between 200 and 800 yards. The following ranges represent target range intervals where all 17 pdr APDS hits are predicted to fail at the given compound angle: 0 degrees.....none 5.............0-200m 10............0-350m 15............150-950m 20............300-1100m 25............500-1300m 30............650-1450m 35............750-1550m 40............800-1600m 45............750-1550m 50............600-1400m 55............300-1100m 60............0-700m When 17 pounder APDS strikes the Tiger II turret front head-on, the compound angle is 10° and the hits should penetrate normally beyond 350m. However, if the APDS strikes the turret front at 11° from armor facing the compound angle is 15° and hits fail from 150 to 950 meters. When 17 pounder APDS struck the 82mm Tiger side armor at a 50° angle and 3511 fps, the hit failed. But when the rounds struck 82mm Tiger armor at the same angle but 3131 fps, it succeeded. The bottom line is that theory and practice show that APDS had a tendency to fail against the evry targets is was designed to combat, Tigers and Panthers and Hetzers (tests which support theory used 67mm to 102mm armor thicknesses).

We're re-evaluating slope effects for uncapped AP hits at angles above 40°, and would appreciate any data that can be provided. Indicate velocity or range. Thank you.

Analysis of published data strongly suggests that German APC and APCBC projectiles during the early war period were inferior to later ammunition. 88mm APCBC (9.54 kg) fired by Flak units 130mm penetration at 0 degrees and 0m to mid-1942 152mm by later war rounds 14.5% less penetration for early war APCBC 50mm L42 AP and APC rounds 70mm penetration at 0 degrees and 0m for AP 72mm penetration for APC 14.8% less penetration for AP when absence of caps is factored in (50mm AP has smaller HE burster than APC) 37mm L45 AP 51mm penetration at 0m and 0 degrees if combat round used in tests 64mm in DeMarre estimate from 75mm L48 adjusted for caps 20.0% less penetration 75mm L24 APCBC 50mm penetration at 0m and 0 degrees 53mm in DeMarre estimate from 75mm L48 5.7% decrease in penetration The early war 88mm APCBC and 50mm AP rounds appear to have about 15% less penetration due to metal characteristics Early war 37mm AP appears to have 20% less penetration due to less effective metal and a large HE burster (1.9% of total weight is HE filler, 0.2% of 75mm L48 APCBC is HE filler) 75mm L24 APCBC appears to have about 6% less penetration due to large HE burster (1.7% of total weight is HE filler, compared to 0.2% in 75mm L48 APCBC). The above data suggests that early war German ammo for 88mm, 50mm and 37mm guns was 15% less effective due to metal type, and large HE bursters reduced penetration by about 5%. Sources: 30 degree penetration data for 37mm L45, 50mm L42 and 75mm L24 from Panzertruppen 1943-1945, by T. Jentz 30 degree penetration data for 88mm L56 early war Flak from Dreaded Threat, by T. Jentz 30 degree penetration data for 88mm L56 later war Flak from American data sheet 75mm L48 APCBC penetration at 0m and 0 degrees, and slope effect multipliers for conversion of 30 degree penetration to 0 degrees, from WW II BALLISTICS: Armor and Gunnery, by L. Bird and R. Livingston

U.S. 57mm anti-tank gun did have limited supplies of APDS ammunition, available summer 1944. Bob McNamara, who designed Advanced Squad Leader, examined American ammo expenditure tables and found 57mm APDS use in Italy and Europe.

The post on 45mm accuracy against PzKpfw I's at over 1000m was brought up to point out that some crews, using what is considered to be a low accuracy weapon, were able to do a good job on long range shots (45mm tank round fired at 760 m/s, not 820 m/s, and loses velocity fast to 1000m and has a very curved trajectory, which decreases accuracy). Hand picked crews could hit with just about anything, and do it consistently. Tiger crews too. And a Canadian 75mm Sherman could hit specific spots on the Panther curved mantlet out to 800 yards. Some ace crews have unbelievable accuracy, that is the point.

Amedeo Matteucci sent me the following web site address due to a story about 88mm Flak use against tanks during the Spanish Civil War (88mm HE demolished the tanks), but it has some good info on 45mm tank gun accuracy: http://knox-www.army.mil/dtdd/armormag/ma99/2candil99.pdf The 45mm accuracy tidbits are late in the article, they note that 45mm fire was very accurate beyond 1000m range, and that the gun sights for the 45mm gun provided for ranges out to 3000m!!!!!! Jentz' books also note that T34 shots at ranges out to 1500m and beyond could be fairly accurate. It is obvious that Russian tank optics, guns and crews could include some very good shooters, especially if a little projectile like the 45mm was able to hit beyond 1000m.

German StuG and other self-propelled vehicles had no turret because it was the only way to get a bigger gun on a tank chassis that would otherwise have too small a turret ring. PzKpfw III tank could not accept a 75L43 or L48 gun, PzkPfw IV could not accept 75L70 or 88L56, PzKpfw II could not accept 76.2L51.5, PzKpfw 38t could not handle a 75L48 in a turret. M10 were supposed to defend against marauding German tanks, and emphasis would be on seeing and firing on attackers. Rate of fire probably is higher in open top unless it is raining or snowing. There have been posts where Sherman air intake was through commander hatch, so snow would be drawn into tank interior along with cold air. Theory was that in North Africa air intake from outside would help cool things inside vehicle. Wonder if M10 also drew air downwards into hull through open turret? Previous posts by Jeff Duquette indicated that tank engagements tended to be short lived affairs, where one side or the other would quickly disengage after suffering losses and total force annihilation was usually rare (U.S. experience, not so on Russian front). So M10 with open top would be used in limited time frame combat, get to breakthrough or go into action against defensive position, blast away and then get out before artillery zeroes in. Regarding StuG profile, Michael Wittmann was able to knockout T34 with the 75L24 gun on StuG IIIA using one shot per tank, by taking advantage of low profile and those scissor periscopes. The StuG would hide in total concealment and look over the LOS obstacle using the scissors scope, where the commander and gunner both had them. So when the StuG was ready to jump out and surprise the T34's it had every thing sighted with low risk. Wittmann took out the T34's by hitting the turret ring. The scissors scopes aided alot due to other factors, higher magnification and light gathering qualities than normal sights in PzKpfw IV, and binocular vision allowed greater accuracy in estimating target range. Regarding German SPG profile, the armor on those vehicles was often shoddy, like Marder, StuG III with 50mm plates and Nashorn, which meant that they either were used at long range where return fire was not expected to be too accurate (or SPG would back away once return fire became too accurate), or small/low profile would take advantage of low cover and reduce enemy hit probability. In terms of accuracy, a low profile is more important than a narror width.

Have read an account of an engagement between German heavy tanks and British Shermans coming down a hill, where the Germans were in a woodline and were camouflaged so well the Sherman crews couldn't see em. Due to low flash and smoke ammo, even when the Tigers fired the Sherman crews could not precisely locate the firers, and quite a few commanders got out of their tanks to try to spot the defenders. The only thing that gave away the enemy location was when the blast of the 88 moved the vegetation and other stuff tied around the gun barrel, or material was moved out of the way due to the blast. In North Africa the British used camo nets over their anti-tank guns, which seems to have been very good at concealment. Russian front stories also seem to have T34/85's and ISU-122's hiding in ambush waiting for Tiger II's, and the Germans don't see the hidden SPG till the firing starts. Concealment of tanks and SPG seems possible, given enough time and talent to do it right.

KV-2 had 110mm rounded mantlet and 75mm at 30° driver plate, which would give the 88mm Flak units some difficulty during 1941 if overpenetrating rounds shattered on driver plate and and mantlet hits took place at 500+ meters range.

The assumption that early war German ammo was inferior to later stuff also explains why 50mm AP penetrates less than 50mm APC, despite: 1. 50mm AP does not have an armor piercing cap, which absorbs about 12% of penetration 2. 50mm AP has a smaller HE burster than 50mm APC Here are 30° penetration figures for 50mm APC and AP at selected ranges: 50mm L42 AP, 53mm at 100m, 43mm at 500m 50mm L42 APC, 55mm at 100m, 47mm at 500m 50mm AP should outpenetrate APC by about 14% or so, but is inferior. The use of soft metal would also explain why 37L45 AP and 75L24 APCBC penetrate so little when they are compared to later German ammo like 75L43. Jentz' data for 75L43 APCBC penetration may also be based on tests with early ammo. Jeff Duquette posted a story some time ago where 88mm Flak units were having their shots shatter against KV and T34 armor at 2000+ meters, and it took 10 shots per kill. If early 88mm Flak rounds were used, and there must have been alot of them during 1942 and 1943, the penetration at 2000m would not be sufficient to get many penetrations against KV-I and T34 front hull, and KV-I turret front. The data provided by Richard Simmie answers many questions, and he did a great job digging into the material. ------------------------------------------------- This is a comparison of published 30° penetration for 88L56 APCBC and an explanation of what it seems to represent: 88L56 Early War Large HE Burster-88mm Flak (9.54kg projectile) 98mm at 100m, 93mm at 500m, 87mm at 1000m 88L56 Later War Large HE Burster-88mm Flak (9.54 kg projectile) 120mm at 100m, 110mm at 500m, 100mm at 1000m 88L56 Later War Small HE Burster-Tiger and Flak (10.2 kg projectile) 127mm at 100m, 117mm at 500m, 106mm at 1000m Early war 88mm ammo combines a large burster with what appears to be inferior steel to penetrate considerably less than later war ammo. 88L56 Flak ammo at 9.54 kg penetrates about 6% less than Tiger ammo due to less weight and greater burster size.