rexford
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Posts posted by rexford
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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
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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
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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
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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
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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 ]
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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.
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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).Originally posted by Jeff Duquette:Lorrin Said: “British evidence shows that the Tiger 88mm L56 and the Flak 88mm L56 fired different APCBC rounds at least through late 1944. Tiger used small capacity round, 88mm Flak used large capacity round.”
The heavier and more accurate 8,8cm Pzgr.39 FES was employed by both the FLAK18 & 36 as well as the 8,8cm KwK36. The Flak18 & 36 were employing the more accurate round as early as 1942.
The less accurate APCBC round employed by the 8,8cm Flak18 & 36 is the 8,8cm Pzgr.Patr.mBd.Z. This round was not employed by the KwK36. The 8,8cm Pzgr.Patr.mBd.Z round has a higher level of shot scatter, or a larger dispersion pattern than the FES round.
Flak 18 & 36 firing pzgr 39 FES had a 50% dispersion zone at 1000m of 0,2m (horizontal) and 0,4m (vertical).
Flak 18 & 36 firing Pzgr.Patr.mBd.Z had a 50% dispersion zone at 1000m of 0,4m (horizontal) and 0,7m (vertical).
KwK 36 Firing pzgr 39 FES had a 50% dispersion zone at 1000m of 0,2m (horizontal) and 0,4m (vertical).
The greater accuracy issue appears to be associated with ammunition type rather than the Tiger-1’s main gun being more accurate than the Flak-36.
Source information:
1) H.Dv.481/541 “Merkblatt fur die Munition der 8,8 cm Flugabwehrkanone 18, und der 8,8 cm Flugabwehrkanone 36” dated May 20, 1942.
2) H.Dv.481/60 “Merkblatt fur die Munition der 8,8 cm Kampfwagenkanone 36”, dated Jan 1, 1943.
John Diehl's analysis of German ammunition in AFV-G2 magazine showed the 88mm Flak 18 & 36 firing Pzgr and Pzgr 39 APCBC.
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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>Originally posted by Other Means:</font><blockquote>quote:</font><hr />Originally posted by JasonC:
Note that over 800-1000m the shell drops about 2m. So basically they set the sight so the round is level with the point of aim at 800-1000m. And the round is above the point of aim by up to 2m, closer than that.
Then they aim at the bottom. This is suppose to hit the actual bottom of the target at 800m or 1000m, and hit higher up but still on the target at closer ranges. Beyond 1000m, the round will land short, not long. So the first round tells them - with a visible short - if they need to increase the elevation.
This relies on a target being about 2m high, however. Not the best practice against a hull down target. And round dispersion could easily make half of the shots miss low at the actual "zeroed" range i.e. 1000m.
It is fine for quickdraw shooting at 800m or less, though, against a hull up target.
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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.
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That's good info. Thanks.Originally posted by K_Tiger:I`m not sure where i read it, but it was a interview with Bobby Woll (Wittmans Gunner) who sayd, that he allways pre adjusted his gun to 800m.
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.
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The Tigerfibel actually says that the 3 man technique be used 'if they have time'. </font>Originally posted by Mr. Tittles:</font><blockquote>quote:</font><hr />Originally posted by rexford:
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
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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.Originally posted by FM Paul Heinrik:I don't really remember much from my econometric studies, but isn't a standard deviation above 2-3% basically, means that the data sample is too small or that what is being hypothesised needs to be redefined. 20%+ is a huge standard deviation.
Also, range estimation is an aquired skill, are the tests preformed using controlled testing or AARs? The more you estimate range the better you get at it, ask any hunter. In Vietnam there were reports of VC mortar crews consistantly hitting targets on their 1st shots (now they might have been infiltrating and pre-marking targets, I don't know).
Regardless, I highly enjoy reading all the gronard info from Rexford.
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.
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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.
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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
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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.Originally posted by Mr. Tittles:My main thought would be that that while the earlier 88mm AP rounds may not have had the accuracy of the later Tiger I 88mm rounds, they may have made up for it with very accurate range/heading readings and vast amounts of rapid fire.
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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
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How does one add a drawing or scanned page to their posts?Originally posted by Mr. Tittles:
Yeah and stop playing with these F_Knives and go do your homework.
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.
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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.Originally posted by flamingknives:Classic! I've now got a mental image of a grog sighting down a toilet roll at a toy tank in the middle of a gym.
The lengths people go to for their hobby!
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 ]
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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.Originally posted by Mr. Tittles:Sights are Optics. German sights were excellent optics at that. his test bears out the value of a triangle with precision being built into the optics.
Having excellent optical qualities only enhances the ability to read the 'triangle'.
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Good question. Previous studies showed that my guessing ability is about average.Originally posted by flamingknives:Incidently, have you tried ranging said toy eyes only? It might be that you're above average at guessing range.
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.
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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 ]
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Additional stats for British, American and German ammo trajectory errors per 100m range estimation variation:
500m
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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
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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
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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
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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 ]
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Good suggestion.Originally posted by Mr. Tittles:Perhaps you should do a run for the 88mmL56 flak gun with both types of AP?
The 88mm Flak guns did have a means of measuring ranges to less than the +/-200m presented here. The rather large rangefinder was part of the kit of this unit (actually most flak had some type of rangefinders).
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.
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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
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75L40, 0.73m
75L48, 0.50m
50L60, 0.46m
88L56, 0.45m
75L70, 0.32m
88L71, 0.27m
1000m
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75L40, 1.63m
75L48, 1.11m
50L60, 1.13m
88L56, 0.97m
75L70, 0.72m
88L71, 0.57m
2000m
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75L40, 3.99m
75L48, 2.72m
50L60, 3.16m
88L56, 2.27m
75L70, 1.75m
88L71, 1.31m
3000m
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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 ]
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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.
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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
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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
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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
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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).
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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.
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"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.
Estimating Range With Gun Sight Triangles: Home Experiments
in Combat Mission: Barbarossa to Berlin
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