lorrin

The past discussions centered on the following pro and con issues (StuG IIIG and PzKpfw IV generally carry face-hardened armor on front): A. British firing tests against 32mm/30mm layered (in contact) face-hardened armor on PzKpfw IIIH front with 37mm thru 75mm AP and APCBC results in an effective single plate resistance of 69mm for the two plates. B. American tests with 37mm thru 90mm APCBC against 30mm/50mm layered (in contact) face-hardened armor on front of PzKpfw IV shows that best test resistance is much greater than a single 80mm plate would provide C. Standard 76mm APBC from T34 would penetrate about 82mm face-hardened at 100m and 75mm at 500m. Since StuG IIIG and PzKpfw IVH carried single plate thicknesses of 80mm face-hardened or layered armor with resistance above 80mm, penetrations at 500m should be rare D. Russians had super hardened, limited availability 76mm APBC round for T34 and field guns that penetrated 90mm face-hardened at 100m and 82mm at 500m, which matches 500m penetration range quoted by JasonC E. Russians also had solid shot uncapped AP designed to kill Tigers from side, which penetrated about 74mm face-hardened at 500m F. Upper superstructure armor on StuG IIIG is highly sloped but thin, 50mm at 51 degrees from vertical and 30mm at 68 degrees from vertical, where the thinner plates which might be vulnerable to 76mm APBC at 500m despite large impact angles (APBC is very good against sloped armor due to flat nose, which cancels many of the ricochet forces that plague sharp or rounded nose ammo). G. Near vertical 30mm/50mm armor on front of StuG IIIG has large bolts and openings through it, is made up of limited size plate and probably would suffer from edge effects on many hits(lowered resistance when hits land near free ends), making it vulnerable to T34 76.2 APBC. H. Tests and combat results from various sources confirm that 2 pdr AP was not very effective against 32mm/30mm on PzKpfw IIIH front I. Combat results with 25 pdr AP against PzKpfw IIIH front suggest resistance equal to 62mm face-hardened and maybe more J. Two homogeneous plates in contact resist penetration with less than the total thickness, because homogeneous armor has less resistance at the surface and there are four surfaces with two plates in contact versus two with one plate. Two face-hardened armor plates in contact present two separate face-hardened layers which have a total combined thickness greater than a single plate with same overall thickness, first face-hardened layer removes armor piercing cap or blunts uncapped AP reducing effectiveness against second face-hardened layer K. Germans gave up on 32mm/30mm face-hardened on front of PzKpfw IIIH and went with single 50mm plates on PzKpfw IIIJ, suggesting 32mm/30mm about the same as one 50mm plate. Germans switch from 32mm/30mm because two bolted plates in contact became a maintenance headache, angled hits tended to shear or bend bolts loosening connections

If the Tiger 88mm is set for 800m and a target is further out, the APCBC elevation above target bottom would require the following increase in mils: 800m, 0 mils 900m, 0.94 mils 1000m, 1.94 1100m, 2.84 1200m, 3.88 1300m, 4.82 1400m, 5.90 1500m, 6.88 1600m, 7.91 1700m, 9.05 1800m, 10.08 1900m, 11.18 2000m, 12.41 A quick and dirty relationship would be to raise the target sight one mil above the normal aim point (target bottom) for every 100m above 800m that the target is estimated to be at. So if the target looks like it is 1200m, raise the triangle point so it is about 4 mils above target bottom if I have it correct. And since the center triangle is 4 mils high, the placement should be close to what is required. Beyond a certain range the relationship may start to vary a bit from the ratio below 1500m or so.

Thanks for the response. The German gun sights worked in the following manner (from GERMAN TANKS OF WORLD WAR II, by George Forty): A. There was a range plate and a sighting plate B. The range plate had the main armament scale marked around the outside amd rotated about its own axis C. The sighting plate, which contained the triangles, moved up and down D. Both plates turned together E. To select a range the range wheel was turned until the marker was opposite the correct range F. Then the sighting mark was laid on the target using an elevating wheel and traverse That's how Forty describes the process (page 103).

Sorry, but I don't keep them. JasonC and a few of the other regular contributors to the various discussions are the best bet. Lorrin

Abovementioned report provided by Miles Krogfus after discussions on German aiming methods.

"and you are showing your test/analytical inexperience." ?

No, I was indicating that it is impossible to describe the 100% shot capture distance for all tests, and certainly did not indicate that it would all be done with one gun. You're reading too much into my statement. When you asked for the 100% distance you did not, to my recollection, specify a 10 shot test so I described the issue in general terms. I did post up the results for the 90% zone associated with 17 pdr APCBC, which should have answered many of your questions regarding the general validity of the German 50% zones. As an aside, when the German reports from 1943 that are currently the subject of my recent posts calculated hit probabilities at 1500m, they did not double the 50% zone dispersion but used it "as is". So it was not common practice to use the doppelte streuung for hit rate estimates.

The report mentioned in my first post was provided by Miles Krogfus in response to a discussion we had on German aiming procedures, range estimation and possible use of battlesight aim type techniques.

Suggest you consult the Tiger Fibel for the answer.

Mr. Tittles, And I told you several times, and showed the procedure with numbers, where one can aim the gun at the target bottom (set triangles) and then set the range. DanielH was the first to note the constant aim/move the triangles around procedure on this forum, to my knowledge, so I mentioned his name. Lorrin

A German report on aim settings and range corrections after a miss indicates that one method is to keep the range setting constant and move the aim point. This is exactly what DanielH was saying that he used in his computer wargames. The report also states that the method of "constant range/move the aim" worked well when ranges were below 1500m, but when combat ranges extended out to 1500m-3000m the method lost effectiveness and crews were advised to use artillery type bracketing with 200m changes. The above procedure would then explain why Bobby Woll and other panzer crew members would set the gun for an 800m range setting as a standard operating procedure: a. if the target was between 0 and 800m and 2m tall (or higher), it would be hit on the first shot with a high probability using an 800m range setting regardless of actual range b. if the target were beyond 800m the gun aim could be quickly changed for the first shot by varying the triangle aim point from the usual "at target bottom", based on the adjustment experience of the gunner and crew range estimates The report is dated September 9, 1943, and my thanks to Michael Rausch for his translation assistance and explanation of the report statements.

A German report dated February 4, 1944, from Panzerjagerabteilung 14, details the use of a battlesight aim procedure for 75mm Pak 40 guns (the procedure is not called battlesight aim). Various examples in the report show how aiming at a longer range than the target is estimated to be at will allow hits against targets within a range spread where the width of the spread decreases as the range increases. If the gun aims for the bottom of a 2m tall target with a range setting of 1200m and using Pzgr 40 ammunition, hits will be scored on all such targets between 855m and 1200m, which allows continuous accurate fire without changing the gun range setting. The report indicates that gun crew commanders keep a table of range settings with them for use in the field, and the table settings are as follows (the German ballistic table results for 75mm Kwk 40 and Pak 40 are in brackets, for comparative purposes): 75mm Pak 40 Pzgr 39 ===================== 0-200m (0-200) 0-400m (0-400) 0-600m (0-600) 0-800m (0-800) 620-1000m (750-1000)* 1020-1200m (1020-1200) 1240-1400m (1260-1400) 1360-1500m (1375-1500) Notes: 1. If a group of 2m tall targets, or single 2m tall tank, is at 1020m to 1200m range, a gun range setting of 1200m will result in a hit. 2. *-for 750 m/s muzzle velocity, our calculations show that setting gun to 1000m range and aiming at target bottom will overfly 2m tall target at 620 by about half a meter but will just hit the top of a 2m tall target at 750m. Report table appears to contain an error for this range. 75mm Pak 40 Pzgr 40 ==================== 0-200m (0-200) 0-400m (0-400) 0-600m (0-600) 0-800m (0-800) 0-1000m (0-1000) 855-1200m (930-1200) 1165-1400m (1205-1400) 1300-1500m (1330-1500) 75mm Pak 40 Pzgr 38 Hl/B ======================== 0-200m 0-400m 455-600m 715-800m 980-1000m 1155-1200m 1365-1400m 1470-1500m The report ranges do not consider the impact of random shot to shot dispersion or scatter, which may result in some misses within the listed range intervals (locations where the trajectory is near the top or bottom of the target and scatter may move the flight path off the target). [ September 24, 2004, 04:31 AM: Message edited by: lorrin ]

Agree that there are some oddball aspects to it, the Panthers at Kursk knocked out some T34's at 3000m so a sight limited to 1500m is just not right. Shows what kind of stuff is possible during wartime. We've had years to go over the stats and compare different sources, they were in a hurry sometime and hadn't been looking at different tanks for a decade or so.

The British used a large number of different ballistic limits, so some variations could occur due to whether 50% of the rounds succeeded, or 80%, or one merely had to punch a small hole allowing light to pass as opposed to having 80% of the round pass through. My data is keyed to 50% success where the round makes it through with most of its mass. But 68mm/30 degrees/500 yards for the 790 m/s 6 pdr APCBC is way too low and may be a typo. 87mm at 30 degrees for 831 m/s 6 pdr APCBC seems high for rolled homogeneous armor, and could be the face-hardened figure or it could be for a lesser degree of penetration (like a small pinhole counts as a success). Most British sources for 831 m/s 6 pdr APCBC have 81mm at 30 degrees and 500 yards for 50% success, so 87mm would be about right for 20% success but not 80%. Look through the John Salt WW II Penetration Snippets and don't rely on one source. Our face-hardened figure for 831 m/s 6 pdr APCBC at 457m is about 88mm with 50% of rounds making it all the way through, so while the site you identified says the penetration is against machineable quality armor (homogeneous) at 80% success it may be a face-hardened figure at a lower success rate.

Same basis as their data, of course. Which is?

The posted penetration data for 6 pdr APCBC fired at 790 m/s on the site you identified is not correct, and the actual muzzle velocity was 792 m/s. It is not equal to 68mm at 0 degrees and 500 yards (457m), and is not consistent with the Ordnance Board Curves. A check on the 6 pdr APCBC penetration at 790 m/s vs at 830 m/s is to take the higher velocity penetration and multiply it by: 87mm x (790/830)raised to 1.43 power. According to our data, the 6 pdr APCBC fired at 792 m/s would penetrate about 97mm vertical at 457m, and the 30 degree penetration would be about 78mm The 6 pdr APCBC round fired at 831 m/s would penetrate about 104mm vertical at 457m, and about 83mm at 30 degrees. So both figures for 30 degree penetration by 6 pdr APCBC at 460m look questionable.

We obtained most of our British penetration data directly from Bovington Tank Museum, so we know what we are using and have the background info for the tests. We collected a set of ordnance board curves for 6 and 17 pdr APCBC, APDS, etc. The John Salt Snippets provide a wide assortment of penetration stats. Before using the info from Bovington or John Salt's Snippets we compared to actual shot-by-shot firing tests at a variety of angles.

The Ferdinand article is also interesting due to the description of what appears to be SU 152's against Tigers and Ferdinands, where the SU 152's totally demolished the attacking Tigers. The Lone Sentry index is at: http://www.lonesentry.com/index.html

These are my last words on the Panther mantlet business until I have better information on the British 6 pdr APCBC trials against the mantlet: 1. Failure of 76mm M62 APCBC against the Panther mantlet beyond 200 yards could be due to shatter gap, and no remarks would be found in the report because no remarks were made on any of the other failures. 76mm APCBC M62 penetrates about 123mm of RHA at 200 yards and 0 degrees, Panther mantlet center is 100mm case, so armor would have to put up 123% of flat rolled armor equivalance to stop 76mm hits beyond 200 yards. And that's on center area hits. Ditto for 76mm M79 AP except the percentage is even higher for flat rolled equivalence. 2. The British trials with 6 pdr APCBC show that the Panther mantlet did not offer any unusual resistance values and the cast armor did not act like it was better than rolled armor. When I have more data the factors can be expressed numerically. 3. Curved mantlet armor may be more resistant than a flat plate, or it may be less resistant. Or it may offer the same resistance for similar impact angle and T/D ratio. The British trials suggest that the Panther mantlet was not capable of stopping 76mm APCBC hits beyond 200 yards unless something else was occurring (like shatter gap), since the 76mm APCBC could outpenetrate 6 pdr APCBC against all sorts of armor. 4. The Isigny APDS rounds bounced due to excessive yaw which impacted the accuracy and penetration capability. 5. 6 pdr hits on the Panther turret anti-tank guns in Italy resulted in 6 pdr failures, which is contrary to the British firing trials. Difficult to explain, lots of possibilities (including subpar ammo). There is what appears to be conflicting data here. [ September 20, 2004, 08:44 PM: Message edited by: lorrin ]

The report suggests that the Ferdinand went into combat with the circular hatch wide open, as does the drawing. This suggests a major vulnerability if Russian infantry got to close quarters.

Following site has some early Russian figures on Panther armor which are interesting and curious: http://www.lonesentry.com/articles/ttt_panther/index.html 85mm glacis at 57 degrees, 75mm lower front hull at 53 degrees. Wonder if they measured these areas?

Found an English translation of a Russian Kursk report on the following site: http://www.lonesentry.com/articles/ferdinand/ Ferdinands fought with open circular hatch in rear superstructure? [ September 19, 2004, 05:51 PM: Message edited by: lorrin ]

Do you have the net address of the standard ordnance catalog? Thanks. Lorrin

Those figures you posted are questionable and we looked at them in the past and disregarded them. We made it a point to analyze published figures before using them, since many "official" numbers are questionable. 75mm M72 AP penetrates about 95mm of vertical face-hardened armor at 0 degrees and 0 yards. 76mm M79 AP was fired at 2600 fps, versus 2030 fps for 75mm M72 AP, and based on velocity differences alone the M79 should penetrate about 95mm x (2600/2030)raised to 1.25 power, or 129mm at point blank. Throw in a larger diameter round and the 0 yard/0 degree penetration figure we just estimates increases some more. 1. Looks like the catalog contains some bad data. 2. There is nothing, anywhere, which suggests that the Panther mantlet was face-hardened. ========================================== Now, would you please explain why a "100mm thick at its center" face-hardened Panther mantlet would defeat the 76mm M62 APCBC round beyond 200 yards? Please show the penetration and armor thickness figures to support your contention? It would be good to see your theory backed by numbers and analysis. My copy of TM9-1907 shows the 76mm M62 round penetrating the following thicknesses of face-hardened armor at 500 yards (the 250 yard penetration would be higher): 500 Yard Penetration of 76mm M62 APCBC Face-Hardened Armor ====================================== 4.76 inches at 0 degrees (121mm, armor is 100mm) 4.15 inches at 20 degrees (105mm, armor is 91mm) 3.65 inches at 30 degrees (93mm, armor is 84mm) [ September 19, 2004, 08:12 AM: Message edited by: lorrin ]

Shatter gap theory as we've been able to detail it results in a penetration failure potential for U.S. 76mm APCBC if the "penetration/effective armor" resistance ratio is between 1.05 and 1.25, more or less. Let's apply that to the firing test results on the Mycenius site. Penetrates 100mm/30 degrees at 500 yards. Well, penetration at 0 degrees is 117mm, resistance of plate is about 125mm at 0 degrees. Suggests above average penetration or below average resistance of armor, with penetration close to effective resistance. So no shatter gap. Penetrates Panther mantlet at 200 yards. Penetration equals 123mm, a hit on the mantlet center is resisted by about 95mm, so the penetration/resistance ratio is above 1.25 at 200 yards but may fall into the shatter gap ratio beyond that range. Just to clarify a point in my previous post, the 250m face-hardened penetration of the U.S. 76mm M79 and M62 rounds is 124mm and 123mm, respectively, which blows apart the theory that the firing trial failures against the Panther mantlet were due to face-hardened armor. Compare the data, throw out the theory.