rexford

You made it sound like this was an actual trial during the war. I take it from the rest of the conversation, this was actually you? </font>

Did some additional experiments yesterday in the empty gym (it's mine, all mine!), and put together the following write-up which is a little more concise: Experiments with a simulated German gun sight of 5x magnification and a scale model T34 resulted in the following range estimation statistics under ideal conditions (gunner able to separate front and side views of target, target fully exposed in the open): 350m to 750m Target Distance ============================ Average range estimate error of 10.9% based on random selection of 70 cases using center of curve and standard deviation Bell shaped curve centered at a 0.58% error with a standard deviation of 13.54% 34 cases 750m to 1000m Target Distance ============================= Average range estimate error of 9.9% based on random selection of 70 cases using center of curve and standard deviation Bell shaped curve centered at a -6.54% error with a standard deviation of 12.03% 48 cases 1000m to 1500m Target Distance ============================== Average range estimate error of 7.8% based on random selection of 70 cases using center of curve and standard deviation Bell shaped curve centered at a -1.77% error with a standard deviation of 10.56% 31 cases 1500m to 2000m Target Distance ============================== Average range estimate error of 8.9% based on random selectionof 70 cases using center of curve and standard deviation Bell shaped curve centered at a -8.17% error with a standard deviation of 10.17% 36 cases Compared to the typical British gunner who was found to average a 20% range estimate error during firing trials, use of the German gun sight triangles would result in a significantly lower first shot ranging error. The interesting thing about a 5x magnification gun sight is that a 2000m target presents the same visual view as a 400m target to the unaided eye in terms of size. As long as the German gunner could make out the front of the tank target from the side (which seems to be possible under some conditions with a 400m range to the "naked eye"), the ability to estimate range would be close to what I came up with. The problem with separating side and front armor is that at small hull angles to the sighter, such as 7 degrees, a 3m front width T34 would show quite a bit of the side armor (6m length) and the perceived width of front and side armor would be: 3m x cosine (7 degrees) + 6m x sine (7 degrees) = 3.7m, which right off the bat throws the range estimate off by about 20%. [ September 05, 2004, 07:28 AM: Message edited by: rexford ]

The trajectory height is measured from a straight line drawn from the gun through the bottom of the target, and changes as the target round changes. The one constant is the point at which the round passes through the gun-target bottom line, which is the gun range setting for zero dispersion. Drawn a Tiger sitting on level ground and a 2m high T34 at 500m distance. Draw a straight line from the Tiger gun through the bottom of the T34 and let the line run down thru the ground. Now draw the trajectory for a 1000m shot, which starts at the Tiger gun and lands on the gun-target bottom line at a point 1000m from the Tiger. The maximum trajectory height of the shot is 2.3m over the gun-target bottom line. Trajectory height is measured against the line from gun to aim point. The Panther Fibel shows this sort of aim line. If the T34 is at 500m the shot flies over the bottom of the tank by about 2.3m, a miss most of the time.

Penetration data for 88mm Flak 18 & 36 firing Pzgr shows two different figures at 30 degrees from vertical, suggesting an improved round at some point (9.6 kg weight). John Diehl's analysis of German ammunition in AFV-G2 magazine showed the 88mm Flak 18 & 36 firing Pzgr and Pzgr 39 APCBC.

i feel the Axis gunners where aided by the Allies using varients of the same model throughout the war. if you've shot at enough Shermans/T34's you know the range at first contact. give or take a small enough margin of error for it not to matter with a HV gun. </font>

The maximum trajectory heights for the rounds discussed in this post are: Tiger I 88mm APCBC 800m aim, 1.4m 900m aim, 1.8m 1000m aim, 2.3m 75L48 APCBC 800m aim, 1.5m 900m aim, 2.0m 1000m aim, 2.5m The Tiger 88 has a higher muzzle velocity and loses less velocity with range percentage wise, so has a lower trajectory height than 75L48 shots with APCBC.

That's good info. Thanks. The following are the computed hit percentages against a 2m high T34 that is in the open and stationary, where the hit rate considers shot scatter due to range estimate errors, random scatter and varying target width: Tiger 88mm APCBC Gun Set at 800m 100% hit rate to 700m 50% at 800m 0% hits at 900m and 1000m Gun Set to 900m 100% hits to 300m 95% hits at 400m 88% hits at 500m 98% hits at 600m 100% hits at 700m and 800m 50% hits at 900m Gun Set to 1000m 100% hits to 200m 93% at 300m 21% at 400m 9% at 500m 19% at 600m 66% at 700m 99% at 800m 100% at 900m 50% at 1000m 0% at 1100m 75L48 APCBC using the same firing technique with an 800m gun setting would score almost 100% hits at every range from 100m to 700m, and 50% at 800m. With a 900m gun setting the percentages would decrease from 100% at 100m to 52% at 500m, and then increase to 99% at 800m: 75L48 APCBC with 900m Aim 100m 100% 200m 100% 300m 98% 400m 61% 500m 52% 600m 71% 700m 98% 800m 99% 900m 50% It's like JasonC says, if the trajectory height is lower than the target height one scores big time at all ranges up to the aim distance, if the trajectory goes over the target height or skims the top some of the hit rates will be around 50% or so in the mid-ranges. And if the trajectory goes over the target height for a while the hit chances will be very low in the middle range area. Good explanation JasonC.

The Tigerfibel actually says that the 3 man technique be used 'if they have time'. </font>

The curve which resulted from the 60 and 65 trial data formed a nice bell shaped normal distribution curve, and the standard deviation was around 12.5%. The data was input as percent error. Normal distribution curves are defined by the mid-point (0% error in our case) and the standard deviation (12.5%), while range estimation by naked eye has the same mid-point but a 25% standard deviation. The standard deviation does not indicate correlation or the niceness of fit in this case, it just defines how the curve spreads out away from the mid-point.

Correspondence with Miles Krogfus brought the following points to light, based on information he received from numerous Tiger vets: A. no indication that 3 man range estimate averaging was ever used B. Various gunners set their guns for 800m to 1000m for the first shot at a tank sized target, a technique that was used by some of the best gunners (aim at target bottom) C. Tiger Fibel sets out technique of using gun sight triangles and perceived target size to estimate range My analysis indicates that setting the gun range for 800m to 1000m and aiming at the bottom of the target would result in a very high hit percentage at all ranges between the Tiger and the range setting. This technique, which is referred to as Battlesight Aim by post-WW II tankers and was hinted at in the Panzertactik book, would be very effective against T34's and Shermans in the open and would enable a Tiger crew to get off repeated shots in quick succession since the range estimate would stay the same.

DeMarre Estimates for German APCR Against Vertical Plate from U.S. 76mm HVAP Range-50L60-75L48--88L56----88L71 0m----162mm-183mm--198mm---325mm 100m-150mm--177mm--194mm---320mm 500m-110mm--156mm--178mm---297mm 800m---84mm 1000m--------131mm--159mm---271mm 1500m--------110mm--142mm---245mm Core statistics from Miles Krogfus follow: APCR Tungsten Core Data Notes 37L45: 16mm diameter and 0.230 kg 50L60: 21mm diameter and 0.335 kg 75L48: 28mm diameter and 0.902 kg, also used by 75mm Pak 40 88L56: 30mm diameter and 1.124 kg, also used by Panther 88L71: 36mm diameter and 2.000 kg Data from Krupp firing tests at 30 degrees from vertical with German tungsten core ammo follows: German APCR Penetration At 30 Degrees from Vertical Range------50L60-----75L48----88L56----88L71 0m---------127mm-----130mm----166mm----247mm 100m-------113mm-----123mm----160mm----240mm 500m--------77mm-----109mm----148mm----220mm 800m--------52mm 1000m-----------------90mm-----132mm----200mm 1500m-----------------70mm-----119mm----178mm Applying a 1.33 slope multiplier to the above table results in the following penetration estimates against vertical plate: German APCR Penetration Against Vertical Plate (30 Degree Data x 1.33) Range------50L60------75L48---88L56----88L71 0m----------169mm----173mm----221mm----329mm 100m-------151mm----164mm----213mm----320mm 500m------- 103mm---145mm----197mm----293mm 800m----------69mm 1000m---------------120mm----176mm----267mm 1500m----------------93mm----159mm----237mm

Although the dispersion data for the Flak 88mm Pzgr shows a marked inferiority to the Tiger Pzgr 39. Rate of fire would be an important factor, as you note.

Mr. Tittles, Just wanted to say that much of my recent research, including the home experiments with triangles, was a result of the questions you've raised on the various threads. You ask good and difficult to respond to questions, and your efforts are appreciated. Lorrin

How does one add a drawing or scanned page to their posts? One other problem at the gym was the neanderthals who kept walking on the 25' long tape measure. They must have been working through the pain and entered the numb zone.

The sight was slightly longer than a toilet roll, being 12" long. The treadmill folks did not like my constant walking between them to take measurements and adjust the T34 position on the floor. The T34 was not just pointing at the sighter, it was placed at angles from straight-on to a pure side view and everything in between. One thing, I forgot to wear my long pants and skinned my knees crawling on the harsh rug trying to estimate range from the T34 height (get down as low as possible for that estimate). Got same general results whether range was estimated using the height, width or length. One thing that stuck out was that a tank at 1000m with 5x magnification looks the same as a tank at 200m with naked eye sighting. It is possible to clearly make out the front and side aspects at 200m with unaided vision, which is an important requirement when one is basing the triangle measurement on the front view and quite a bit of the side armor is visible. The wheels and shadows give away the side aspect. With 2.5x magnification, a 1000m target is the same as a 400m target with unaided eyes, which still allows for a somewhat clear division of front and side armor. I peered out my window at home looking at the Macy's ring road, which is 400m way, and tried to estimate range to the UPS trucks with a ruler with mils markings drawn on it for 2.5x magnification. Not easy, but possible. [ September 02, 2004, 04:59 AM: Message edited by: rexford ]

Well said. German sights had superior light gathering ability and clarity, and when that is added to the triangles one gets a very good sighting system.

Good question. Previous studies showed that my guessing ability is about average. We've done similar experiments tossing pennies and trying to guess the range, looking at cars or trees at some distance on the street and guessing range, and the average range estimation error was 20% to 25% using the eyes alone. We compared our estimated ranges to measured distances using a yard stick or tape measure where possible, or used a laser range finder. Having a 4 mil triangle to compare the perceived height or width of a T34 against is a great aid.

The trajectory displacements per 100m gun setting error suggest that hits might be rare at many ranges, since a 100m error may result in an aim error of more than 1.20m. Hits will still occur with very large aim errors due to two factors: A. random dispersion, which adds to or subtracts from the mean trajectory to cause high and low diversions from the average flight path B. the bell shaped nature of the range estimation curve Looking at the range error distribution, a 20% average range estimation error is a bell shaped distribution that varies from the maximum individual probability at 0% error, with 68.3% of the errors within 125% of the average (+/- 25%) and a few at 50% or more. The following factors convert the average range estimation error to a random distribution if one rolls a 20 sided dice (1-20): A. range error = range x average error x 1.25 x dice roll factor Roll/Dice Roll Factor 01/0.03* 02/0.09 03/0.16 04/0.21 05/0.28 06/0.34 07/0.42 08/0.49 09/0.56 10/0.64 11/0.72 12/0.80 13/0.89 14/0.98 15/1.09 16/1.22 17/1.36 18/1.54 19/1.79 20/2.22 Note: *- suggested that a small percentage of these scores be associated with 0% error, 0.2 to 0.33 might be reasonable. For the Tiger 88L56 APCBC at 1000m, the trajectory displacement from the aim point is 0.97m per 100m gun setting error. If one is firing on a 1.2m high target, this allows for a maximum range error of 1.2m x 100m/0.97m or 124m to place the average trajectory on the target vertical height (aim at center). Using the above dice roll factor table, if the Tiger crew averages a 10% (0.10) range estimation error the "range x average error x 1.25 x dice roll factor" must be 124m or less: 124m = 1000m x 0.10 x 1.25 x dice roll factor, resulting in a factor of 0.99 or less to place the average trajectory on the target. According to the above table, a roll of 1-14 would be successful (70% probability). If the average range estimation error was 20%, the equation would be 124m = 1000m x 0.20 x 1.25 x dice roll factor, and the dice score range for a success would be 1-8 (40% success). The 1000m vertical success rate against a 2m tall target with a 1200m range estimate would be 30% (roll 1-6), which only applies to having the average trajectory cross the vertical height of the target at 1000m. Due to random dispersion, the final hit percentage would be less due to up and down variations from the average trajectory and left and right misses. The overall hit probability would also be lowered by nervous and unpredictable errors by the gunner, who might have the gun aimed far in error and still fire, hitting nothing but air even at close ranges. [ September 02, 2004, 06:14 AM: Message edited by: rexford ]

Additional stats for British, American and German ammo trajectory errors per 100m range estimation variation: 500m ==== 17 pdr APCBC, 0.35m 2 pdr AP, 0.54m 2 pdr APCBC, 0.42m 6 pdr APCBC, 0.46m (2600 fps muzzle velocity) 6 pdr APCBC, 0.41m (2725 fps muzzle velocity) U.S. 76mm APCBC, 0.45m U.S. 76mm HVAP, 0.27m U.S. 37mm APCBC, 0.37m German 50L42 APC, 0.68m German 75L46 APCBC, 0.45m 1000m ==== 17 pdr APCBC, 0.75m 2 pdr AP, 1.39m 2 pdr APCBC, 0.96m 6 pdr APCBC, 1.03m (2600 fps muzzle velocity) 6 pdr APCBC, 0.94m (2725 fps muzzle velocity) U.S. 76mm APCBC, 1.00m U.S. 76mm HVAP, 0.63m U.S. 37mm APCBC, 0.85m German 50L42 APC, 1.68m German 75L46 APCBC, 1.00m 2000m ===== 17 pdr APCBC, 1.75m 2 pdr AP, 4.01m 2 pdr APCBC, 2.42m 6 pdr APCBC, 2.58m (2600 fps muzzle velocity) 6 pdr APCBC, 2.35 (2725 fps muzzle velocity) U.S. 76mm APCBC, 2.44m U.S. 76mm HVAP, 1.61m U.S. 37mm APCBC, 2.19m German 50L42 APC, 4.69m German 75L46 APCBC, 2.44m 3000m ===== 17 pdr APCBC, 3.01m 2 pdr AP, 7.59m 2 pdr APCBC, 4.39m 6 pdr APCBC, 4.68m (2600 fps muzzle velocity) 6 pdr APCBC, 4.25 (2725 fps muzzle velocity) U.S. 76mm APCBC, 4.34m U.S. 76mm HVAP, 2.97m U.S. 37mm APCBC, 4.00m German 50L42 APC, 8.91m German 75L46 APCBC, 4.34m The interesting aspect of the trajectory displacement per 100m range estimation error is that the U.S. 37mm APCBC is more accurate than the Tiger 88L56 to almost 3000m, and U.S. 76mm HVAP is a better round in terms of trajectory accuracy than every round except 88L71 APCBC. The vertical trajectory displacement per 100m range error is only one piece of the overall accuracy puzzle, and would be supplemented by wind effects (lighter rounds are more impacted), trunnion cant, lateral jump and random dispersion. Just plain bad shooting would also play a part, although the projectile characteristics might play a minor role in how bad the shot ended up being. The trajectory displacement for a given range estimation error approximately equals: 4.936 x (flight time to target x flight time to aim range - (flight time to target squared)) The flatter the trajectory the less flight time to the target (gravity does not pull the round down as much), and the less variation from the aim point for a given gun setting error. Even though 76mm HVAP loses a higher percentage of its initial velocity at all ranges than 76mm APCBC, the high velocity of the HVAP results in a flatter, lower trajectory. [ September 02, 2004, 05:17 AM: Message edited by: rexford ]

Good suggestion. I believe that there is a combat report in Jentz' Dreaded Threat where a group of 88mm Flak guns took on a pack of T34, and it took about 12 shots per tank kill. Didn't sound like the 88's were too successful in getting hits that day.

For comparison purposes, it is useful to compare how much a 100m range estimate error misses the intended target mark by (center of mass aiming was followed by the Americans and British): TRAJECTORY HEIGHT ABOVE AIM POINT FOR A 100m RANGE ESTIMATION ERROR 500m ==== 75L40, 0.73m 75L48, 0.50m 50L60, 0.46m 88L56, 0.45m 75L70, 0.32m 88L71, 0.27m 1000m ===== 75L40, 1.63m 75L48, 1.11m 50L60, 1.13m 88L56, 0.97m 75L70, 0.72m 88L71, 0.57m 2000m ===== 75L40, 3.99m 75L48, 2.72m 50L60, 3.16m 88L56, 2.27m 75L70, 1.75m 88L71, 1.31m 3000m ===== 75L40, 7.11m 75L48, 4.84m 50L60, 6.00m 88L56, 3.93m 75L70, 3.12m 88L71, 2.22m All rounds are APCBC except for 50L60 which is firing the APC round with a poor ballistic shape (high drag resistance and light weight combine for relatively rapid velocity drop-off with range). For preliminary estimate purposes, the trajectory distance from the aim point is proportional to the 100m figures presented above times the actual range estimation error divided by 100m. Double the listed error for a 200m error in range setting, half for a 50m error. A +10% range estimation error results in the following trajectory error with regard to the aim point for the 75L70 gun: 0.16m high at 500m 0.72m high at 1000m 3.50m high at 2000m 9.36m high at 3000m A +20% range estimation error results in the following trajectory error with regard to the aim point for the 75L70 gun: 0.32m high at 500m 1.44m high at 1000m 7.00m high at 2000m 18.7m high at 3000m Random dispersion or scatter would be added or subtracted from the average trajectory placement noted above. While the Germans initially aimed the gun at the target bottom they added an adjustment to the initial range estimate to bring the ideal shot placement near the center of the target height. [ September 01, 2004, 03:52 PM: Message edited by: rexford ]

British trials during WW II showed that the average crew was capable of estimating range to a target tank with an average error of about 20%, when only the eyes were used. The distribution was bell shaped with a standard deviation of 25%. To see whether those German gun sight triangles would improve things and to examine the ins and outs of the triangles, two trials were conducted. The trials consisted of placing a scale model T34 M42 on the rug and estimating the range in meters using a homemade gun sight. The gun sight actually had no magnification, but 2.5x and 5.0x magnification was modeled by increasing the size of the triangles and multiplying the actual scale range of the model by the appropriate multiplier (if the scale range to a perceived target was 300m using the straight model scale, it would represent 750m with a 2.5x gun sight). 65 trials were conducted with the 2.5x gun sight model, and 60 with the 5x sight, and both tests resulted in an average range estimation error of 10% from 350m to 1000m (bell shaped curve, standard deviation of about 12.5%). The 5x magnification sight trials resulted in faster range estimation, due to a larger target size, clearer target image and larger triangles. It is also likely that the 5x gun sight would retain a low average error to a longer range than the 2.5x sight, since an important aspect of the tests was a visual distinction between the front and side armor when both were in view, which would be evident longer with the 5x sight. Various precautions were taken to assure that the person with the sight had as little knowledge about the new T34 placement as possible and relied totally on the sight triangles for the estimate. Going by the triangle trials, which represent one case (target in open terrain), the Germans would have approximately halved the first shot average range estimation error of the British through use of the gun sight triangles. The abovementioned trials were run in an empty house, and to see how commotion and an unfamiliar and uncomfortable setting impacted triangle estimate the model tank and tape measure were brought to the gym downstairs. The average error from the mean for the busy gym was similar to the quiet house case (about 12.5%), but the center of the gym curve resulted in the most likely shots being 10% long at the center of the curve, while the quiet house curve was centered about the actual target range. The noise, unfamiliarity and stress of the gym setting through off the accuracy, which suggests that crew experience and calmness would be important. Note on using Triangles to Estimate Range: The triangle at the center of the sight is 4 mils wide and 4 mils high, and a T34 M42 at 1000m has a 3 mil front hull width, 2 mil height and 6 mil hull length for estimating purposes (3 mils cuts a distance of 3m at 1000m). If the T34 front hull width is measured at about 4 mils using the triangles, the estimated distance equals 1000m x (3 mils/4 mils) or 750m. A 3 mil measurement for the height would result in an estimated range of 1000m x 2 mils/3 mils or about 650m.

After setting up a bracketing program on my computer, the following results were obtained for 75L48 and 75L70 APCBC against the front of a stationary T34 M43: 21 Guns Firing at 21 T34, Gun Stops Firing After a Hit Program Stops At End of Fourth Round Attempts Assumes Excellent Guns with Low Dispersion 1250m ===== 75L48 1- 4 of 21 shots hit (19%) 2- 5 of 17 hit (29%) 3- 8 of 12 hit (67%) 4- 4 of 4 hit (100%) 21 of 21 hit 75L70 1- 6 of 21 hit (29%) 2- 8 of 15 hit (53%) 3- 5 of 7 hit (71%) 4- 2 of 2 hit (100%) 21 of 21 hit 1500m ===== 75L48 1- 3 of 21 hit (14%) 2- 4 of 18 hit (22%) 3- 7 of 14 hit (50%) 4- 4 of 7 hit (57%) 18 of 21 hit 75L70 1- 4 of 21 hit (19%) 2- 6 of 17 hit (35%) 3- 6 of 11 hit (55%) 4- 3 of 5 hit (60%) 19 of 21 hit 2000m ===== 75L48 1- 2 of 21 hit (10%) 2- 3 of 19 hit (16%) 3- 4 of 16 hit (25%) 4- 6 of 12 hit (50%) 15 of 21 hit 75L70 1- 3 of 21 hit (14%) 2- 4 of 18 hit (22%) 3- 5 of 14 hit (36%) 4- 6 of 9 hit (67%) 18 of 21 hit The initial range estimates had an average error of 20% from the actual range and followed a bell shaped normal distribution, from 0% error to +/- 49%. The Germans required that crews be able to hit a target at 1200m-2000m by the fourth round at the completion of their training, which appears to be possible in most cases. If the initial range estimates were less than 20% in error on average the 75L48 would probably make it (+/- 200m would do it, which is extremely good estimating for 2000m targets and was not considered reasonable).

If a Panther targets a 1300m T34 M43 with an initial range estimate of 1050m (20% error on low side), the range setting would be 1150m for the navel area. The shot would land 128m short of the target on level ground and the BoT correction would bring the second round closer to the target but still short on the great majority of tries. Bracketing after the first miss would bring the second try to a point where 90% would hit. In this case the Panther might use bracketing or burst on target for the second shot, with significantly different results.

"I would guess that at ranges under 1500m, the panther would need about 2 rounds and it would not need to use bracketing till 1500m+ or so." Sir, it is okay to guess but please recognize that initial guesses may not be correct. As I mentioned in an earlier post on another thread (did you read my discussion on BoT, which corrects some misconceptions about the method's effectiveness), burst on target doesn't work with high misses, which is half the misses. And it won't work with rounds that are short by quite a bit, which is a good share of the short misses. BoT will not lead to great second shot corrections on a good share of the shots were it might be used. The Germans also instructed gunners to use BoT type corrections to 1200m, and bracketing thereafter. Panthers would have to use bracketing quite a bit on shots beyond 1200m (2m high T34 M43): average range estimate for 1300m target is 1550m for 20% error. Set gun to 1650m for bottom aim. First shot is 3.5m over target bottom, a random dispersion for this case brings shot down -.2m for 3.3m over target bottom. Panther uses bracketing to decrease range setting by 200m, for 1450m shot. Trajectory is 1.5m over target bottom, dispersion brings round down -.4m so it lands near target center (1.1m over bottom). A hit. This is for one case out of a million or billion possible for the target range and target height. If the initial range estimate is 30% in error, which it could be, the 1300m target is estimated to be at 1700m and the gun is set for 1800m. The first shot is 4.8m over target bottom with a random dispersion. Second shot uses range setting of 1600m, is 2.6m high at target and overflies by 0.6m. Third shot uses 1400m range setting, shot is 1.0m over target bottom for middle area hit.