Mr. Tittles

The Germans had test requirements for tank gunners that were based on correcting fire. They had to hit targets at unkown ranges with so many rounds. They werent being tested for luck but for skill. The Germans trained 100s of thousands of gunners for ATG, Panzer and Assault guns. They certainly had a reputation for accuracy. I dont buy Jasons trust the gun and damn the corrections. Even he says that you usually dont know the range, so aiming and eventually correcting must be done. I think he overstates this supposed zeroing error also. Zeroing targets typically have a easily identified center area and the magnification of the sight would allow the gunner to put his 'cross-hairs' acceptably close. Once the gun is zeroed, than any pointing errors are a function of the human not the gun. It isn't built into the gun. [ August 29, 2004, 09:48 PM: Message edited by: Mr. Tittles ]

I wonder if a tank would have to reaim after each round when zeroing. That is, would the gun be repeatable enough in returning to its firing position? So just aim center of mass and fire a shot group without constant sight adjustment? I read of how M48 tanks zeroed. They adjusted the sight to the shot group. They aimed at a center of the target and the middle of the actual shot group was then where the sight was adjusted to point. Then they aimed for the center again and fired a new shot group to verify adjustment of the sight. "The Tank Commanders Guide" compiled and edited by William L. Warnick, Lt. Col. John G. Cook, USA Ret.,and Dr Robert A. Baker of The United States Army Armour Human Ressearch unit Fort Knox, Kentucky Military Service Division and I quote; "Zeroing is firing the gun to ascertain the point of projectile impact, then all instrument crosshairs should be aligned with the center of the shot group on the target." "The gun is said to zeroed if the check round hits within 2 feet of the aiming point at 1500 meters" (for the M41 90mm gun)

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).

What method to use is not always range dependant. Yesterday while driving, I entered a long stretch of road once I came over a slight rise. In front of me the road stretched about half a mile down a gentle slope and then up another slope. It occured to me that if I was firing rounds and they flew over the cars ahead of me that were going up the slope ahead of me, I would be able to see where they landed quite clearly and judge the amount short or long they were. This being because the cars ahead of me were on the forward slope and long rounds would still strike ground that was in my LOS. On very flat terrain, it is very difficult to judge long rounds simply because the target is in the way of viewing where they land. The road had electric power poles every 100 yards and I was quite sure of the range. I was just using my naked eyes but having any binos would have made it even easier. But Jason brings up a good point about 'tweaking'. Its a human reaction to fiddle with things because the mind wants to correct a situation once any data is presented. In the APCR thread, I was not happy with the area spread that rexford is claiming for shot (single) dispersion. I was not buying some of the double dispersion spreads either. Hitting targets (which are basically characterized by area lxw) would require a certain level of precision (which is also a area function). If the spread of shots is greater than the area size of the target (or even very close), then corrections can not be made without firing quite a few rounds to first 'zone in' the shot spread. You are actually trying to move this shot spread area onto the target area. As Jason points out, if your life is on the line, then you do not want to hang around and be a target area yourself. I would venture a guess that if using bracketing, shorts are more valuable and range estimation should go for the conservative initial guess. [ August 29, 2004, 12:44 PM: Message edited by: Mr. Tittles ]

Rexford claims the dispersion actually follows a bell shaped curve. Its not random in that there is no prediction to it, he claims the germans took data on where 50% of the rounds would impact and that statistical methods can then be used to predict where the other 50% will impact. Please review the the APCR thread for more on this. i am sure people would like to hear your opinion. http://www.battlefront.com/discuss/ultimatebb.php?ubb=get_topic;f=23;t=010029 [ August 29, 2004, 12:27 PM: Message edited by: Mr. Tittles ]

The russian 45mm had a very low velocity HE round. It was used against US troops in Korea and could snipe HMGs out of existance. In Panzerjaeger (forgot the author) the 37mm is used against all types of targets. In some cases to defend against enemy infantry that have got very close. The author describes seeing individuals in his sights and plinking away at them. I believe he runs out of HE and kills enemy troops with AP rounds.

In Tiger Tanks-Green on pg 46, there is a report from British testing of a Tiger I gun. Its stated that a 5 shot group of 16in by 18in was obtained. Note that it is not saying that is the 50% zone, its saying that all 5 rounds landed in that area at 1200 yards (1100m~). 3 out of 5 rounds fired at a moving target (15mph) were also hits. I would assume they used a known range method.

http://tiger1.info/EN/Target.html Heres the German gun calibration target for roughing in the gun at 50m. I have seen pics of Germans putting fine wire across the end of the gun tube for just this purpose. The next procedure would be to fire at a known range. Recently I read of a Tiger I that could not adjust on Target. Every correction brought the rounds either too close or too far. The range was around 1000m and the crew would have nailed the enemy long before the third round. A technician arrives and finds the sight was loose! Every firing moved the sight a little so that corrections were meaningless. He tightens sight, roughs it in and fires at 1000m to zero the gun.

I am beginning to think that this double dispersion business only applies to doubling the 50% data and applying it to first round shots. I do not think that doubling any other area, like the first sigma area, means anything. And having range data like pre-measured ranges (either through firing shots/MGs into those area as tests or at previous targets, measured ranges from dedicated rangefinding equipment, surveying, etc) throws this double dispersion ballpark figure out of the window. I know that much of the penetration model in the game is based on rexfords work, is the hit model based on double dispersion?

At 25m it would not be apparent that a gun had unacceptable dispersion. The rounds would make holes that overlap or very nearly overlap. Even a 75mm Sherman could do this. The repeatability would allow the gun to be zeroed for center fire and adjustment to the crosshairs. But unless the gun is fired at some range (hopefully 500m+), the real accuracy of the gun is not apparent. Its basically an open ended rough-in at best. By zeroing at a close range and then testing at a real battle range, you have a test grounded at two points and a basis for accuracy. The real nature of the dispersion must be taken into account if it follows a distribution as you say. Look at all the data for the German guns at 100m. In some cases its 0 vertical and horizontal. Can you really say what the dispersion is by looking at the 100m data? What about 25m data? Do you think the dispersion goes away by ignoring it? Ana analogy is as follows: You put a 4 in by 4 in pole in the ground. Its 4 feet high. You climb to the top and nail another 4 by 4 at the top and its nailed at its very end. Its hanging off into space 4 feet. You claim that you used the overlapping 4 inch area to insure its square and therefore you know that at 4 feet away from the pole, you can predict where the other end is. [ August 28, 2004, 08:56 AM: Message edited by: Mr. Tittles ]

Guaging range is probably not a linear function and more a function of the range itself. Guaging out to 1000m might be linear but it might go sevrely non-linear beyond that. It might start out at 100m as a 5% error and ramp up t0 10% at 1000m. Beyond 1000m it might ramp faster depending on the optics involved. If its just a human eye then its probably the worst case. Eyes using binoculars would be better and enhanced stereoscopic devices better still. Theres a chance that a coincidence type range finder may be used and the error would go down dramically. The case of when to use bracketing or BOT is largely a function of being able to percieve the fall of shot. The ability to guage the depth perception being critical. If firing from a slight height advantage and the TC has a very good stereoscopic binos, he would be able to percieve long and short shots and guage the amount of error to correct the fall of shot on target. If firing at a tank on the back edge of a hill, long shots can not be seen to fall on terrain in relation to the target. They just fly over. Since flying over and the height difference between flying over is extremely difficult to judge, the best course of action would be to bracket a round to fall short and 'walk' a round up to the target. Tall tanks, like the Panther TC position, gives a built in height advantage albeit a small one. [ August 28, 2004, 10:05 AM: Message edited by: Mr. Tittles ]

For bracketing by 75L48 APCBC vs T34 M43 at 1200m, following results were obtained (avg error of 16% in first round range estimate, single dispersion, firing by 20 guns vs 20 targets on first try): 4 of 20 first rounds hit target 8 of 16 second shot rounds hit target 3 of 8 third round shots hit target 3 of 5 fourth round shots hit target 18 of 20 targets hit by fourth round or less, as per German training requirements that a target be hit by fourth round from 1200 to 2000m. Average number of shots per target, 41 shots to kill 18 T34, for 2.3 shots per kill on average. Since you have a 10% failure to pass the class (2 out of 20 need 5+ rounds), then these gunners in your test are barely average (well, there were quite a few A's and B's so maybe 10% washout is not that bad?). You are also at the minimum range stated in the test. The test calls for 1200m+. I realize this is just one run, but like dispersion itself, how do you know where this one run lies on a graph of runs? Interesting how single dispersion is seeming to fall in line with both combat reports and tank school testing. Note the additional requirement to hit a moving target in the final test. It is somewhat easier because the range is 800-1200m. It differs in that it is not an unknown range and the crew could set the gun for 1000m initially. This probably models a defensive action where general range data is known and the enemy is advancing into a kill zone. If 3 rounds are needed for a moving target; Could a stationary target under similar circumstances be a 2 round sure thing? Less than two rounds? [ August 28, 2004, 10:08 AM: Message edited by: Mr. Tittles ]

In Tankerschool (end 1943) the crews had to fulfill the following: 1st Exercise: Using HE on a target at unknown range but less than 1200 meters. Own tank stationary target stationary (size of AT-Gun) Criterion to pass: 1 Hit out of 4 rounds 2nd Exercise: HE on a target at range greater 1200m, six HE rounds authorized (target the same as in 1) Criterion to pass: 1 Hit 3rd Exercise: AT round on a (stationary, frontal) tank target at greater than 1200m. 4 rounds authorized Criterion to pass: 1 Hit 4th Exercise: AT round on a moving (ca. 20km/h) tank target across the field of vision at 800 - 1200m. 3 (!!!) rounds authorized Time: 30 sec. Firing time, target moves 150 m Criterion to pass: 1 Hit Notice: No Examination on tanktarget stationary below 1200 m !!

The average number of rounds fired at a T34 M43 to score a hit in the math simulation was: 1 round each for 2 tanks hit 2 rounds for 1 tank hit 3 rounds each for 9 tanks hit 4 rounds each for 6 tanks hit 55 rounds fired for 18 kills You forgot the rounds fired at the two non-hit tanks! You need to add 2 tanks not hit with 4 shots gives you 8+55=63. You should have run simulation till all tanks were hit. The other two tanks would probably require another round? So 65 rounds and 20 hits? So 3.25 rounds per hit? Also, the hit=kill may not be reality given the armor protection and the performance of the gun at these ranges. The report said they would have destructive effect but not an absolute kill/burn. Panzertruppen 2 also states that Panthers could open up at 2000+ meters. They state that every 4-5 rounds was a hit at 1500-2000m (battlefield conditions, its precision was probably better). Even the Panther HE had this performance against guns and buildings at these ranges. Didnt the French test the Panther gun after the war and find similar results? I recall that they fired HE at target tanks at some great range and could get repeatable hits. 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. [ August 27, 2004, 06:00 PM: Message edited by: Mr. Tittles ]

I think any understanding of antitank fire should start by documentation of the guns precision. That is, the precision of the gun when all other variables are eliminated. So the crews ability to guage range, nerves, etc. are not to be part of the methodology. In the case of the churchill 6 pdr, it would have been best if all the guns were fired by the same gunner (hopefully the most experienced) and that they were checked for alignment before the shoot. Hopefully they were all about the same in barrel life. In any case, the majority of the weapons showed some excellent precision against a very short target. To get that many hits against a 0.6 m x 1.5m target (less than 1 sq m!) at that range is remarkable. [ August 27, 2004, 04:38 PM: Message edited by: Mr. Tittles ]

A. 2 of 20 first round shots landed on a T34 M43 front aspect B. 1 of 18 second shots hit the target (didn't fire at previous hits) C. 9 of 17 third shots hit the target D. 6 of 8 fourth attempt shots landed on the T34 So, after four shots with bracketing 18 of 20 targets were hit. But it took 63 rounds. In Panzertruppen 2 on pg 41, theres a report about 75mmL43 Panzer IV. Pzgr39 were fired at 1200m to 1600m. Every hit had a destructive effect. 2-3 rounds were expended per tank killed. Gr38HLB was seldom used. One to five rounds were required to set an enemy tank on fire. Note: 17 KV1, 26 T34, 1 T26, 1 MKII, 3 MKIII, 1 General Lee destroyed by 4 Panzer IVL43 during Feb to Mar 43 Note that many accounts state that AT fire would be used against a target till it caught fire. That is, 2-3 rounds may have been used to destroy a tank, but that could mean multiple hits also. The 75mmL43 and 75mmL48 were the most produced KWK weapon in the German army. Many millions of rounds were produced for this weapon. It was also in use for years during the war. The schools would have had a solid understanding of this weapon and its capabilities. The APCBC round had a very small HE cavity and this lends itself to a more solid equally distributed rotational balance. I think the second round shots above show a very low percentage (1 of 18). I would think it would be better than the first round shots by a factor of two (about 3 of 18 given good observation of first round shot). But I do think you are getting more in line with reality. [ August 27, 2004, 04:32 PM: Message edited by: Mr. Tittles ]

Bell shaped curves are not all the same. I do not say I am anything beyond stats 101 but I know there are different shaped bell curves. The diagram above shows how it can vary.

My gut feeling is that the distribution needs to be tighter. Basically, this is an density or area distribution question. The Germans were probably annoyed that the data was not circular in that all the points were centered about an aim point. They therefore broke up each hit location into its x and y component. Suppose that we apply the sigs to area instead of the individual lengths? So for a 1 m by 1m area, the first sig would 1.48 sq m or 1.2mx1.2m? The 95% 2 sig would be 2.91 sq m or 1.7m x 1.7m or a total vertical component of +/-0.85m from the aim point? Notice that doubling the 1mx1m data dispersion yields 4 sq m (2mx2m). Perhaps the Germans were saying that doubling the 50% zone gives a battlefield fudge when the range was known. [ August 26, 2004, 04:09 PM: Message edited by: Mr. Tittles ]

The next procedure is ADJUSTMENT OF SIGHTS FOR 1,000 INCH FIRING. With 1,000 inch firing trials (about 83 feet or 25.4m) dispersion would not be an issue. The Americans checked the sights without having to use 1000 yard shots, and thus avoided having to deal with random dispersion in the vertical and lateral directions. This is laughable.

It would be nice to have a shoot n hide command like shoot n scoot. Basically take one shot and hit the dirt.

Ive written many test procedures and the manufacture of tank guns and antitank guns would have certainly had an acceptance criteria. More than likely it would be something like: 1. mount test sight (this would be the same sight used for all tests, the sights would also have an individual acceptance test but the gun is proofed with a 'known-good' sight). 2. Boresight weapon to 25m to get sight and barrel aligned. This could be a large piece of paper with two crosses on it. One for the barrel and one for the sight. This will rough in the weapon. 3. Fire 10 rounds at 100m. 5 must be in a rectangle no larger than x/y. 8 must be within X/Y. Adjust shot group to center of target to align sight. Refire test. 4. Fire 10 rounds at 1000m. 5 rounds must be in x1/y1. 8 must be within X1/Y1. Adjust as in the first test. If more than one round is outside X2/Y2, then repeat test. The x's and y's are obviously derived from the test data. The 50% zone is certainly known. The gun is therefore calibrated for repeatabilty and accuracy. To me, this would be a minimal test procedure. The gun may actually need to be fired several times before testing just to break it in.

A German speaking friend of mine at work, whose father flew German aircraft at a production center during the war, translated the ballistic table column headings for me. Here are some of the more interesting ones: a. Hit Percentage for a target area of 2.5m x 2m two percentages are given, second one is in brackets The footnote associated with hit percentage in brackets translates as: " Parenthetical values valid for battle condition dispersion (double 50% dispersion)" HIT PERCENTAGE AT A KNOWN RANGE TUNGSTEN CORE AMMUNITION DOUBLED DISPERSION RANGE...50L60...75L48...88L56...88L71 100m..........100......100........100.......100 300m..........100......100........100.......100 500m............98........99........100.......100 700m............84........88..........95.........98 900m........................69..........87.........93 1100m......................52..........74.........85 1300m......................37..........63.........76 1500m......................25..........52.........66 1700m......................19.......................58 1900m......................14.......................50 Just to be clear, did the German report specify that its for a known range? Shouldnt this be titled 'First Round Hit Percentage...'? Could you post both columns? I take it this data is second column? I would still like to see 75mmL48 HE and HEAT data (both columns) Thanks PS I edited my post above. Almost within a minute of your post.

50.00% are outside 1.00m/0.90m. 31.74% are outside 1.44m/1.30m. 25.00% are outside 1.66m/1.49m 20.00% are outside 1.85m/1.67m 15.00% are outside 2.07m/1.87m 10.00% are outside 2.37m/2.14m 05.00% are outside 2.82m/2.55m 01.00% are outside 3.72m/3.36m 00.50% are outside 4.03m/3.64m You truly think outside the box. Half are in 0.9 sq m. The other half are spread out in a little over 8 sq m. If we double the 0.9 sq m to 1.87 sq m we only get 68%. If we triple it, we get about 3/4. It just seems that there is a concentration and too much non-concentrated. [ August 24, 2004, 05:01 PM: Message edited by: Mr. Tittles ]

No you misunderstand. He was only doing a drill where his part of the drill was to announce a full stop and his 'Fire!' alert was just that it was safe to fire without motion. The TC/Gunner may have had a command of 'Target!' that would alert the driver to come to a halt before the driver declares 'Fire!'. Once the driver felt the recoil, and barring a command from the TC to remain still, he would get it in gear and move on. He was not designating targets.

75L48 APCBC 100m....0.1m/0.0m 300m....0.2m/0.2m 500m....0.3m/0.2m 800m....0.4m/0.4m 1000m..0.6m/0.5m 1300m..0.8m/0.7m 1500m..1.0m/0.9m 2000m..1.6m/1.3m 2500m..2.4m/1.8m 3000m..3.3m/2.3m So for a 75mmL48 APCBC firing at 1500m, the vertical spread could be up to 3 m. This is so sloppy that walking rounds in would be nearly impossible. The main technical difficulty is that the overall area spread of the rounds is greater than the target area size. And this is with a known range mind you. Trying to adjust after the first round is a waste of time. You would have to fire two or three rounds without adjusting just to get some idea where your 'firing-box' is centered. The fact that 50% of the rounds WOULD have the needed precision makes me question still the methodology used here. If 50% of the rounds land in 1 sq m and the other 50% land in the surrounding 8 sq m; is this a bunching up bell function? [ August 24, 2004, 09:08 AM: Message edited by: Mr. Tittles ]