Marco Bergman Posted July 2, 2011 Share Posted July 2, 2011 While collecting the data for a new version of my UI mod which shows the slope effect values of armour on all the vehicles in CMBN, I made a simple spreadsheet which calculates the slope effect values. It occurs to me that since this spreadsheet contains armour thicknesses, angles, slope effect equilalents and gun penetration for every CMBN vehicle and gun, a printout of this spreadsheet could be a useful reference for gamers. The calculations used internally in CMBN are based on the equations and charts contained in: "World War II Ballistics and Gunnery" by Lorrin Rexford Bird & Robert D Livingston The most important factors considered in-game based on this book are the reduced resistance of cast armour, and the slope effect of armour plate. I'm not sure how specific the game is concerning national differences in cast armour resistance ( probably very), but the average cast armour multiplier is x0.87 i.e. cast armour has only 87% of the penetration resistance of rolled plate armour. Slope effects change with the T/D ratio ( thickness of armour vs shell diameter ) which means that smaller calibre guns are seriously affected by sloped armour, very large calibre guns less so. The charts below are for a 75mm round, since this is the most common in the game. This is what I'm basing my mod on. I'm ignoring a bunch of other factors like shatter gap and manufacturing flaw modifiers ( although the game doesn't) and basing the calcs on 90° angle to the target. Note that turret front values are usually for the turret amour not mantlet (except M10 and Tiger I) but a mantlet hit is probably hitting 1.5x-2x this thickness. Looking at the charts, you can see that a Pz IVH at 500m penetrates 123mm, and that a M4 (mid) is equivalent to Turret: 87mm, Upper hull: 131mm, Lower hull: 56mm, so you would expect a non-penetration against the upper hull. A M4A1 (mid) has Turret: 87mm, Upper hull: 76mm, Lower hull: 56mm, so would be vulnerable everywhere. The Sherman penetrates 95mm, and the Pz IV has Turret: 50mm, Upper hull: 82mm, Lower hull: 83mm, so penetrations against every location would be expected. Links to charts for the main calibres: 37mm http://i52.tinypic.com/sztv1d.png http://i52.tinypic.com/2d2jbpd.png 57mm http://i54.tinypic.com/w7d854.png http://i52.tinypic.com/f2oglv.png 75mm http://i51.tinypic.com/b635ee.png http://i56.tinypic.com/hrzv29.png 88mm http://i55.tinypic.com/2nhkej5.png http://i55.tinypic.com/nuzde.png The spreadsheet is available for those interested here: http://www.captskidd.com/cmn/slopeeffectCMBN.zip All gun penetration values taken from the Bird/Livingston book. Missing values calculated from the charts in Terminal Ballistic Data vol3 (Ordnance Dept, 1945). German armour values taken from "Encyclopedia of German Tanks of WWII" by Doyle, Chamberlain, Jentz American armour values taken from "Sherman", "Stuart", "Half-track", "Armored Car" by R.P. Hunnicutt Here's the calcs from the book: Homogeneous and Face Hardened armour treated as equivalent for slope effect calculations. Cast armour multiplier used for both nationalities: x0.87 Shell is assumed to strike the target at 90° vertical obliquity. Compound angle = arccos(cos(Angle1) x cos(Angle2)) - not used since I have specified 90° horizontal obliquity to target. Slope effect calculation (APCBC & APC) at 90° to target: A = angle to vertical T = armour thickness D = calibre of striking shell Effective armour resistance (0° to vertical) = T x F x (T/D)^G Angle < 55° F = 2.71828^(0.0000408 x (A^2.5)) G = 0.0101 x 2.71828^(0.1313 x (A^0.8)) 55° <= A < 60° F = -3.434 + (0.10856 x A) G = 0.2174 + (0.00046 x A) 60° <= A < 70° F = 0.00000518 x (A^3.25) G = 0.00002123 x (A^2.295) 70° <= A < 85° F = 0.0678 x (1.0634^A) G = 0.1017 x (1.0178^A) 0 Quote Link to comment Share on other sites More sharing options...
Marco Bergman Posted July 2, 2011 Author Share Posted July 2, 2011 Mod preview: 0 Quote Link to comment Share on other sites More sharing options...
Vanir Ausf B Posted July 2, 2011 Share Posted July 2, 2011 I can't believe this post just sunk down to the bottom of the page! What's wrong with this forum? The mod looks good. It's cluttered, and I know there is no way around that, but I may use it anyway. But I will definitely be printing out that spreadsheet and the formulas. I've been looking for those. 0 Quote Link to comment Share on other sites More sharing options...
Barrold Posted July 2, 2011 Share Posted July 2, 2011 looks good Marco BDH 0 Quote Link to comment Share on other sites More sharing options...
Wego McPbem Posted July 2, 2011 Share Posted July 2, 2011 This looks awesome but I think I'm too dumb to make good use of it. Love your ui mod btw, very useful. Keep up the great work. 0 Quote Link to comment Share on other sites More sharing options...
dieseltaylor Posted July 2, 2011 Share Posted July 2, 2011 Very nice. Thanks. Would you like to post them on the wikia? With of course all the detail not just the charts : ) http://combatmission.wikia.com/wiki/Combat_Mission:_Battle_for_Normandy 0 Quote Link to comment Share on other sites More sharing options...
Other Means Posted July 2, 2011 Share Posted July 2, 2011 Great stuff as usual Marco. 0 Quote Link to comment Share on other sites More sharing options...
xian Posted July 2, 2011 Share Posted July 2, 2011 Very useful stuff indeed. Thanks for putting in all that effort. Can't wait to DL. 0 Quote Link to comment Share on other sites More sharing options...
siffo998 Posted July 3, 2011 Share Posted July 3, 2011 first i want to say very nice work...! but i have two little corrections: first: self-propelled guns in game (like stug III or the jagdpanzer 4) do not use the term "turret" but the term "superstructure" armor second: the tiger tank ingame also has an additional armor term (4 in total)... the turret armor: like menntioned in your sheet the superstructure armor: like mentioned in your sheet as upper hull the upper hull armor: 60mm at 80° angle (at the front) the lower hull armor: like mentioned in your sheet just wanted to note that so that you could maybe correct it because some people might get confused by the different terms ingame and in your sheet... nontheless...very nice work... very time consuming 0 Quote Link to comment Share on other sites More sharing options...
Agua Posted July 3, 2011 Share Posted July 3, 2011 Thank you Marco! I wondered how in the world Chris with CM Database was ever going to be able to compile this info since the #s are opaque in BN. 0 Quote Link to comment Share on other sites More sharing options...
Steiner14 Posted July 3, 2011 Share Posted July 3, 2011 Wow. Incredible. Thank you so much! 0 Quote Link to comment Share on other sites More sharing options...
Steiner14 Posted July 3, 2011 Share Posted July 3, 2011 Links to charts for the main calibres: 37mm http://i52.tinypic.com/sztv1d.png http://i52.tinypic.com/2d2jbpd.png 57mm http://i54.tinypic.com/w7d854.png http://i52.tinypic.com/f2oglv.png 75mm http://i51.tinypic.com/b635ee.png http://i56.tinypic.com/hrzv29.png 88mm http://i55.tinypic.com/2nhkej5.png http://i55.tinypic.com/nuzde.png What is the difference between the pics? They seem to contain the same data. 0 Quote Link to comment Share on other sites More sharing options...
Bastables Posted July 3, 2011 Share Posted July 3, 2011 Really nice Marco 0 Quote Link to comment Share on other sites More sharing options...
Marco Bergman Posted July 3, 2011 Author Share Posted July 3, 2011 What is the difference between the pics? They seem to contain the same data. The only difference is in the yellow line for slope effect at 0 degrees. For example, the Jadgpanzer IV (early) has 60mm @ 50 degrees superstructure front. For a 37mm shell, this equates to 136mm For a 57mm shell, this equates to 125mm For a 75mm shell, this equates to 118mm For a 88mm shell, this equates to 114mm The more slope, the more effect and also the thicker the armour vs the calibre, the more effect. 0 Quote Link to comment Share on other sites More sharing options...
Marco Bergman Posted July 3, 2011 Author Share Posted July 3, 2011 but i have two little corrections: I am not unaware of these issues. You might like to bear in mind that I made this spreadsheet for my own use to do the calcs for my mod. There were three considerations for me: 1) CMBO only tracked 3 locations per side of the vehicle and I have a mod that deliberately reflects the CMBO layout while hopefully improving it. 2) there just isn't room for more data. 3) It was a quick spreadsheet. I know what my labels mean I just put this up as is to see if anybody is interested. If I decide to put the charts up on the repository as a reference, then I will expand and relabel, because glacis and mantlet should both be listed. But that is quite a bit more work and the mod is taking up all my little free time at the moment so don't hold your breath. 0 Quote Link to comment Share on other sites More sharing options...
Fetchez la Vache Posted July 3, 2011 Share Posted July 3, 2011 I can't believe this post just sunk down to the bottom of the page! What's wrong with this forum? I saw this post, something went "pop" in my head and I started bleeding from both ears. Not sure this a good sign. I may have suffered a haemogrogembolism. :-( 0 Quote Link to comment Share on other sites More sharing options...
Vanir Ausf B Posted July 4, 2011 Share Posted July 4, 2011 A few discrepancies I noticed between the charts and the values in the game as stated in the CMBN manual. Sherman M4 (75) Late: Chart shows front upper hull armor 64mm @ 47°. Manual says 51mm @ 56° (same as M4 Mid). Sherman M4A1 (75) Mid: Chart shows front upper hull 51mm @ 46°. Manual says 51mm @ 56°. Sherman M4A1 (75) Late: Chart shows front upper hull 64mm @ 46°. Manual says 51mm @ 56°. Panther D and A: Chart shows front lower hull 60mm. Manual says 63mm. I have no idea which is correct. 0 Quote Link to comment Share on other sites More sharing options...
siffo998 Posted July 4, 2011 Share Posted July 4, 2011 I am not unaware of these issues. You might like to bear in mind that I made this spreadsheet for my own use to do the calcs for my mod. There were three considerations for me: 1) CMBO only tracked 3 locations per side of the vehicle and I have a mod that deliberately reflects the CMBO layout while hopefully improving it. 2) there just isn't room for more data. 3) It was a quick spreadsheet. I know what my labels mean I just put this up as is to see if anybody is interested. If I decide to put the charts up on the repository as a reference, then I will expand and relabel, because glacis and mantlet should both be listed. But that is quite a bit more work and the mod is taking up all my little free time at the moment so don't hold your breath. hm sorry if my post was to ambiguous but it wasnt meant to be a offense (or complaint) at all... i just tried to help you improving your mod... 0 Quote Link to comment Share on other sites More sharing options...
Marco Bergman Posted July 4, 2011 Author Share Posted July 4, 2011 Sherman M4 (75) Late: Chart shows front upper hull armor 64mm @ 47°. Manual says 51mm @ 56° (same as M4 Mid). Sherman M4A1 (75) Mid: Chart shows front upper hull 51mm @ 46°. Manual says 51mm @ 56°. Sherman M4A1 (75) Late: Chart shows front upper hull 64mm @ 46°. Manual says 51mm @ 56°. Panther D and A: Chart shows front lower hull 60mm. Manual says 63mm. A) Don't have the game on hand so will check tonight. Can't remember which glacis type this model has in the game. I could easily be mistaken. & C) Hunnicutt gives hull front as 37-55 degrees. 46 is average. Have used average, especially of angles, in several places. D) This seems to be a relatively new finding, based on actual measurement, same as the 50mm lower hull on the Ausf G. Might update to suit. 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted July 4, 2011 Share Posted July 4, 2011 Marco, hi, Truly fantastic work.... I use your great mod and now to have figures in table form is stunning . BTW... Seeing we are allowing ourselves to be nerdish about these matters . For the L40 75mm use gun I think you will find you are using the penetration figures for the developed but never used tungsten round for that gun. The APCBC figure should be about 85mm at 100m and 75mm at 500m. Will check when I have time. Also... the Panther upper front hull 80mm plate was of very low quality and its effective zero degree equivalent was reduced by about 20%. Say 165mm on your scale. Great stuff.... thanks... You have done wonders.... All the best, Kip. 0 Quote Link to comment Share on other sites More sharing options...
kipanderson Posted July 5, 2011 Share Posted July 5, 2011 Marco, hi, For the US 75mm gun and the US 76mm gun you may have used the penetration figures against Face Hardened German armour plate. By the second half of ’43 there was very little of this stuff around, 90% of German plate was homogenous. For the L40 75mm gun the figures you are after are 100m/88mm, 500m/81mm, 1000m/73mm, 1500m/65mm and lastly 2000m/59mm. This is why the US 75mm gun can “just...” handle German MarkIVH and StugIII lower front plates which have vertical equivalent of around 80mm with slope and quality taken into account. But at over 1000m the Sherman gun struggles against such plate. Take a look at page 63 of the Rexford book. Great stuff.. All the best, Kip. 0 Quote Link to comment Share on other sites More sharing options...
Narses Posted July 5, 2011 Share Posted July 5, 2011 This was certainly a huge job and its so well done. Congratulations on an important improvement. 0 Quote Link to comment Share on other sites More sharing options...
Marco Bergman Posted July 5, 2011 Author Share Posted July 5, 2011 Marco, hi, For the US 75mm gun and the US 76mm gun you may have used the penetration figures against Face Hardened German armour plate. By the second half of ’43 there was very little of this stuff around, 90% of German plate was homogenous. Take a look at page 63 of the Rexford book. Kip, you are correct, I did use FH figures. In the Rexford book p66-68 the following vehicles are listed as having FH armour: Pz IV G: TF, TS?, TR? UHF,UHS, LHF, LHS Pz IV H: TF, TS?, TR? UHF,UHS, LHF, LHS Pz IV J (early): TF, TS?, TR? UHF,UHS, LHF, LHS Panther D: UHF,UHS, LHF, LHS Panther A: UHF,UHS, LHF, LHS Stug IIIG:UHF,UHS, UHR, LHF, LHS, LHR That covers a pretty wide selection of vehicles, especially when you add in all the lighter vehicles which tend to have FH. So from a mod point of view, given only enough space for one set of figures, it seemed to make sense to use the FH penetration figures. I welcome your comments. 0 Quote Link to comment Share on other sites More sharing options...
aka_tom_w Posted July 17, 2011 Share Posted July 17, 2011 Thank You! What a FANTASTIC job! Nice Work! 0 Quote Link to comment Share on other sites More sharing options...
GerryCMBB Posted July 17, 2011 Share Posted July 17, 2011 Hello Marco: The spreadsheet has the data for the 75mm only I think. Could you post the spreadsheet files for the other calibers - so far there is just a pgn for these? Thanks very much, Gerry The spreadsheet is available for those interested here: http://www.captskidd.com/cmn/slopeeffectCMBN.zip 0 Quote Link to comment Share on other sites More sharing options...
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