rexford

I have read a report where a defensive M-10 in Normandy was able to knock out 3 of 4 Panthers in a column on a road with a few shots (side and rear hits), without any return fire. This was at very close range. The fourth Panther escaped because of the camouflage, the M-10 did not see it. Things change at close range.

SU 100 had 75mm of front upper hull armor. Some one suggested that 90mm HE was more effective than 75mm HE, which is not always the case and renders some select comments about my comments as off-base as always. Some folks just seem to always miss the point, or the boat. I guess some people can only grasp a fragment of my notes on HE fragments.

While U.S. 90mm HE has more explosive than Sherman 75mm HE, 75mm high explosive puts out a greater number of effective fragments at all distances from impact. Sherman 75mm HE is better than 90mm HE in terms of casualty production, and probably rate of fire, too. And as German ballistic data and independent analysis shows, the slower HE rounds from 75mm armed Shermans have an advantage against troops in the open that 90mm HE would not. 75mm armed Shermans were an exceptional infantry support weapon. Tiger tanks were very effective against Russian anti-tank guns, as evidenced by large numbers of ATG in Tiger kill totals, due to crushing overrun maneuvers and great accuracy hitting guns with direct shots. 90mm HE would have some advantages due to a heavier round with more HE filler, but 75mm HE put out a higher fragment density.

76mm HVAP could not penetrate Panther glacis at practically all combat ranges, and the firing test penetrations appear to be fluke hits against badly flawed and microscopically cracked glacis plates.

Rush job on 76mm HVAP was necessitated by poor showing of 76mm APCBC in France. Didn't M10's fight Panthers or Tigers in Italy prior to June '44? American calculations left out shatter gap and other factors. In initial combat against Panthers, M10's get a few penetration against Panther: 1. through hull MG 2. ricochets off mantlet At really close range, where initial M10-Panther combat took place, most hits land where they are aimed, namely the glacis plate. A few land on MG ball and drive it in, a few hit bottom of mantlet and bounce through hull top and kill crew members.

American planning prior to Overlord indicated that the 76mm gun firing APCBC was sufficient to penetrate the front hull of Tigers beyond 1000 yards, and the same range for Panther mantlet. No need for 90mm gun on tanks when 76mm takes care of German heavies. Shatter gap changes ranges to 50 yards against Tiger front and 200 yards against Panther. Firefly 17 pounder firing APCBC could not penetrate glacis of Panther, but could penetrate mantlet. And could defeat Tiger front hull, and mantlet. American calculations indicated that 76mm gun was all that was neeeded.

Currently researching mantlet ricochets off rounded Panther mantlet for a probability model, and CM board assistance would be appreciated. Could someone point me to the web site where the story on the fellow who specialized in these penetrations is located. And point me towards any past CM threads on this subject. The Canadian chap who made an art with his mantlet bounce penetrations seemed to indicate that the mantlet area where a hit had to strike was very small, and that the effectiveness of the hit depended upon a round wounding or killing a crew member. This seems to suggest that the Canadians were using 75mm APCBC without an HE burster, just like the British. Can anyone verify if the Canadians used inert fillers in their ammo in place of the HE material. Thanks for any help.

The Firefly IIC used the all-cast M4A1 hull type. Was it the early or late model M4A1 hull? The early M4A1 hull had 2" thick driver and bow gunner hoods at 37°, the late model M4A1 hull had 35° for driver and 47° for bow gunner hoods with 2.5" thickness. The early model hull would also be very prone to flaws since it was manufactured prior to October 1943 when quality control and heat treatment was improved, while the late model M4A1 was built with the maunfacturing improvements in place. Thank you for any help you can provide on this question.

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Panther G and PzKpfw IVJ ended the face-hardened armor use for those tanks.

The next few days will produce errata pages dealing with face-hardened penetration of Russian APBC, for which no published data or info exists. Putting together a model for this required extensive review of combat penetration range reports against German tanks, and the estimates will be combat report based. Paul Lakowski provided a modern report that tested a blunt nosed penetrator against homogeneous armor, where projectile hardness matched Russian APBC and armor hardness was similar to WW II American armor. The results suggest that DeMarre type equations can be used to estimate penetration if a few data points are found. The estimates will be the best that currently exist, since none exist, but they will match some combat reports and be reasonable. Our book states that face-hardened penetration data for Russian APBC is one of the major research issues from WW II, and our estimates will address the problem. Following tank areas were face-hardened: PzKpfw III and IV frontal armor, Panther D hull front and side, Panther A hull side, StuG III front, early Tiger II turret side. Sherman 75mm penetrates 81mm of homogeneous armor at 500m, and 95mm of face-hardened plate. Face-hardened armor penetration is a major issue.

In response to Michael emrys post, thanks for remembering those long ago days. I was a contributing editor at Campaign magazine and contributed to AFV NEWS, The General and various other publications. The AFV To Kill system that was contained in one of my Campaign magazine articles was adopted for use in Advanced Squad Leader. Our current work on an armor miniatures system uses the data from our book to significantly improve upon the accuracy of armor miniatures hit resolution, though the new work is a bit more involved.

Publishing errata for the book was discouraged by some friends since it might look bad. Since the changes were important and we did not anticipate major future revisions, we wanted book users to have the correct information as early as possible even if some sales might be lost due to appearances. One of the strongpoints of CM has been the willingness of BTS to consider the need for changes as they arise, and to implement justified revisions. Some typo's were contained in the original CM publication (75L48 muzzle velocity and penetration, tungsten core slope effects), and the game has been corrected. Large productions are bound to have a few things here and there in the original versions that could be improved upon. After living with the book data and equations for many years, and using the information in wargame design and posts on various sites, the validity of published information looks good.

A response to the Wargamer reviews that clarifies some points and responds to reviewer questions has been posted on the following site: http://www.wargamer.com/cgi-bin/ultimatebb.cgi The response is in the After Action Reports section. Book errata and the web site address at Saumur for existing and any future additions or clarifications are mailed with each copy and Charles received the errata with his order. The book equations and findings were developed over a 25 year period, and extensive proofreading and review of equations was done prior to publication. The Russian APBC penetration curves were received and analyzed late in the game and the original equations were thought to be okay. We then found that the APBC slope effects for angles above 55° were not as accurate as could be, and we developed better equations and a revised curve. The source we used for 90mm T33 ammo had 2700 fps muzzle velocity, the actual figure was 2800 fps. And one penetration at range figure was incorrect. While we did not use footnotes, the bibliography is annotated so that the sources include a statement as to what is relevant to the book. There are about 13 pages of references at the back of the book. Note that both reviews in The Wargamer indicate that our book is the only one of its kind, and they emphasize the value as a reference. Both reviews recommend the book. We're developing an armor miniatures system for micro-armour and larger scales, and have used the book data to produce wargame tables and procedures. Extensive play testing indicates that no major changes to book material is anticipated beyond those already included as errata. The stuff in the book and errata works well and produces good results. So, in response to reviewer questions, we have looked things over carefully and used the equations and curves after the need for the original errata, and things look fine.

One of the book aspects which we are particularly proud of is the Tiger mantlet section, which presents three scaled drawings of the mantlet on one page, with views from the front, side view through MG area and side view through vision openings. These drawings represent the state of the art work on Tiger mantlet as they indicate thickness through the armor, as well as weakened areas that were hollowed out. The presentation of these drawings took a combined and lengthy effort from both book authors, Mr. Byrden from Ireland and Mr. Erk from Saumur Armor Museum. Photographs from the Saumur Museum were used in the book to illustrate various important issues regarding Tiger mantlet resistance, including the tapered mantlet edges and the 100mm thick turret front bars that back-up the tapered mantlet edges.

One of the book errata deal with tungsten core shatter, which primarily occurs when tungsten rounds strike at over 3300 fps and hit at certain angles, which mostly impacts APDS. In tests against German tanks, APDS would often fail when it had too much penetration, which we thought was due to wobble. It was due to nose shatter. Guess tungsten wasn't as great as people thought. Data is presented in book errata for tungsten shatter as a function of impact angle and velocity.

Thanks for kind words on book. We are presently working on face-hardened penetration estimates for Russian APBC ammo, for which there are no sources or even hints. And a simplified hit resolution system is under development for major U.S. and German vehicles, which is for armor miniature game table use and may be expanded to other countries forces. The face-hardened penetration figures for Russian APBC will be released in near future as book errata. Thanks for helping to get the word out.

Discussion of T34/85-vs-Pershing combat in Korea on OnWar site presented actual hit percentages from over 100 tank engagements; M26 firing APCBC and HVAP 0-350 yards: 89% hit percentage 350-750 yards: 69% 750-1150 yards: 46% Somewhat higher for HVAP and lower for APCBC. These hit probabilities are lower than what comes out of a mechanical calculation using trajectory, range estimation error and correction through bracketing. The figures may be depressed from target in open due to full or partial hulldown status, moving targets, etc. 89% from 0 to 350 yards does suggest a few things about the ability to hit at close range, even with various factors that might depress expected number against stationary target in open.

If rate of fire were the primary concern for moving fire, the manual wouldn't stress that moving shots were emergency use at point blank range. The gyro is moving through an arc, the tank may be rotating while the gyro is moving (which keeps the gyro in swing mode), the ground may be choppy and a good shot may never be lined up. And even if it is lined up, the swing of the gyro makes it an "iffy" thing. Gyro inaccuracy is alot more than rate of fire problems, which may be considerable if the tank approaches the enemy at an angle (the gun would be constantly moving, making follow up shots a task and a half in terms of getting a round in the breech). The reason why Pershings don't have gyro stabilizers may help answer questions regarding the usefulness of gyro's. M10 and M36 probably didn't get gyro's cause tank destroyers were supposed to be light, and maybe they had to shoot from protected locations due to thin armor. Did M18 have gyro stabilized fire? If Pershing does not have gyro's for moving fire, this kind of suggests that stabilizers were not felt to be important (which suggests other things about moving fire during a period when Allied tanks were advancing). The British concepts about moving fire may have been responsible for the losses leading up to Alamein, which would not be the first time that a concept was held valuable but didn't work in practice. The Turks at Gallipoli knew that the British did not allow rifles to be loaded during bayonet charges, so the Turks came out into the open and prepared to shoot up the infantry charge. Does the British use of empty rifles with bayonets prove that the concept resulted in effective bayonet charges? Does the British use of moving fire prove that it was effective? Jeff made some references to Brazen Chariots and the status that real tankers afforded to fire on the move. Things that real tankers talking should hold more weight than arm chair theorizing.

The post by MarkIV is important, it lays out the mechanics of gyro use: "b. Crew teamwork....(2) The driver warns the gunner when rough terrain is ahead. When crossing rough terrain, the gunner does not fight the gun (attempting to keep it on the target by spinning the elevation handwheel), but waits until the stabilizer has regained control of the gun and the action has smoothed out." Real terrain may look smooth from inside the tank but has little changes that foul accuracy. Action may never smooth out if driving across a plowed field. "(3) The stabilizer does not lay the gun. It tends to keep the gun where it has been laid; that is, it eliminates extemely jerky vertical movements caused by the movement of the tank. Even with a stabilizer, the gun does not hold constantly on the target. The gunner watches the swing of the gun through the target and fires as the proper sight setting crosses the target." Firing as the gyro swing of gun reaches target? Sounds "iffy" and not easy to do without practice, like hitting moving targets. Except here one is firing on a stationary target with a moving gun!!!!!!! "(4) Laying for deflection is easier when the tank travels at a slight angle to the target instead of head-on." Cause it minimizes up and down rotation of tank relative to gun elevation. Moving fire sounds very inaccurate except at point blank range, which is what the U.S. manuals state. At 500m it sounds near impossible.

Based on the data in our book (WW II BALLISTICS: Armor and Gunnery), following is data on 75mm HE rounds: U.S. 75mm HE 14.6# projectile, 1.7# HE filler German 75mm Sprngr.Patr.KwK(34) 12.6# projectile, 1.9# HE filler German 75mm Sprgr. 42 12.7# projectile, 1.4# HE filler German 75mm Sprgr. 34 9.8# projectile, 1.0# HE filler Fragment density and velocity is function of metal quality, ratio of HE filler-to-total weight (more explosive per metal weight means more fragments), HE filler effectiveness (does 1# of German HE filler equal more or less than 1# of U.S. stuff), etc. U.S. 75mm HE puts out more effective fragments than 76mm and 90mm HE, so it is pretty potent.

A 0.15° change in tank angle represents a 0.63" inch difference between front and rear hull of a 20' long tank. 0.15° change in aim angle is about If a tank is moving and closing on a stationary target, chances are the tank is vibrating about a mean value, and the gunner will see the target going up and down on scope. If gunner watches target and notes midpoint of "vibration" they may be able to adjust aim based on mid vibration. Pilots flying instrument approaches to erratic beacon signals (which can change direction completely due to distance and intervening trees) may direct aircraft towards center of swinging pointer arc. Center of "vibration" is assumed to be correct course. If moving tank is on level ground without major vibration and the front of the hull suddenly pitches up by 0.15° compared to rear hull, a shot aimed at the center of a 500m target will miss (shot passes target at 1.3m above aim point). It would seem that the problem when shooting from a tank that has the gun "vibrating" through a vertical arc is that the gun sights would depict a target that is moving up and down. If the normal gun elevation aim for a 500m target is 0.244° and tank movement pitches the gun up by an additional 0.15°, the resulting weapon elevation is 0.394° (61% increase). This raises the 500m trajectory by 1.3m.

The ability to hit a target from a moving tank can be explained very simply. Say a Panther is moving towards a sitting T34 at 500m, the 75L70 is aimed at a 500m range and the gun is set against target center. If the gun elevates 0.15 above the range setting between aim and firing, due to a bump in the ground, a change in slope or a vibration in the running gear, the trajectory goes 1.3m over the aim point, and misses the T34. 500m x tangent (0.15°) = 1.3m higher trajectory for a given distance Fields generally have some slope changes, roads may have extremely small dips or grade variations, tank suspensions may generate some angular rotation of the front hull relative to the rear. It does not take alot of angular change to cause 500m shots to miss.

The U.S. test curves for 122mm APBC penetration have been downloaded onto the Yahoo! Tankers site at http://groups.yahoo.com/group/tankers One must start an account to access the site. Penetration curves are in Files section. 1500m penetration of Panther glacis (85mm at 55°) is predicted by curves if good quality armor (same as test plate), and Russian tests show greater than 2500m range when armor is not so good. Curves for APBC are flat nosed variety ammo, sharp nosed AP without ballistic caps was limited to no penetration against good quality Panther glacis armor, and 600 to 700 meters against poor glacis plate. The slope effects for Russian APBC, as well as penetration estimates for other Russian APBC rounds, have been compiled in our book.

If those penetration ranges are calculations, use them with care. Sherman armor on 56° glacis tanks is usually flawed, T34 front hull is high hardness and brittle on 75mm hits, none of this is usually included in WW II calculations.