cbo

<BLOCKQUOTE>quote:</font><HR>Originally posted by Formerly Babra: I'm pretty much hoping that cbo is right, and that these are all IC Hybrids. It certainly wouldn't make much sense to change turrets on a IIA (though I doubt it's as difficult a conversion as suggested) when more likely candidates are available. Still no word from BTS on THEIR reasoning for inclusion of the IIC.<HR></BLOCKQUOTE> Helge just send me some CM data and from that it seems that they have a Sherman IIC but not a IC. So I guess it could simply be a blooper. Regarding the rebuild of the vehicle, the turret rings of the Sherman IIA and the VC are the same, but the interior layout is rather different. There would be no room for the 17pdr rounds in the wet stowage boxes for 76mm ammo on the hull floor, so basically the whole ammo stowage would have to go and be replaced by Firefly 17pdr bins. The turret basket of the two turrets were also different, but whether that would have any effects on the fittings inside the IIC hull, I dont know. But it would require some effort for the fitters in the field. But of course, anything is possible, I wont dispute that, I just like to see some proof that it was done before accepting it. Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by Spook: Also, you argued earlier that IC Hybrids had a relatively sharper edge to their front hull curvature than for an M4A1. The lighting on the front hull is quite sufficient to Babra's tank, IMO, to show no such "sharpness". So the portrayed tank is weighted to the IIC in my view.)<HR></BLOCKQUOTE> No, the side hull of the I Hybrid around the turret is a tad more "peaked" than in the Sherman II. The front hull is nearly identical. But it would impossible to really see either way under all that cammo, tracks etc. <BLOCKQUOTE>quote:</font><HR>Originally posted by Spook: The funny thing to this whole topic's start (concerning the IIC) was the argument stated that the "IIC never existed because no photographic evidence exists to prove it." The "IIC" photos provided since are now argued as insufficient to prove the IIC. But they've similarly failed to prove Hybrid to me also.<HR></BLOCKQUOTE> A slight correction. There is no pictoral evidence of the IIC, nor is there any source material to prove its existence. All the books I've seen that claims that there were such a thing as the IIC either shows a picture of the IC Hybrid or something that could be anything and does not give any pointers to production orders, field-manuals etc. anyting, something that could actually prove its existence. The Hybrid does not need proving. There is a ****load of nice photos of vehicles with little if anything obstructing the view of the vehicle. Asking me to prove the Hybrid is like asking me to prove that there ever was a German Tiger tank But here is a picture of a Sherman Firefly IC Hybrid complete with Typhoon rockets. Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by Formerly Babra: You are right. Am I missing something? A IIC is a Sherman II armed with a 17 pounder. Why wouldn't the hatches be the same if it was converted from a IIA? <HR></BLOCKQUOTE> They would, but the Sherman IIA is the British designation for the M4A1 armed with the US 76mm gun in a new and completely different turret. So if the critter pictured above is a Sherman IIC, then you have to accept that they ripped the new turret and 76mm gun off a Sherman IIA, basically gutted the vehicle for ammo stowage etc, then found a spare 17pdr turret and put it on top (if at all possible) and rebuilt the stowage arrangements. All this when they would have had plenty of 75mm armed Sherman Vs to put the turret on. This is pretty far fetched and even if this is what happened, it would still only be a one-off like the Grizzly Firefly or the M4A3 Firefly. Claus B [This message has been edited by cbo (edited 08-27-2000).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Formerly Babra: Mystery solved. Here's a nice clear pic of a Sherman IIC of the 8th Princess Louise's (New Brunswick Hussars). Churchill track has been welded on for protection and the 17 pounder has been camouflaged to look like a 75, but there's no mistaking this vehicle. The caption underneath it read in part "many people say the IIC never existed..." <HR></BLOCKQUOTE> Problem is you still cannot see the rear hull and that is the critical part. The front hull could just as well be a IC Hybrid and probably is. I you look at the hatches, they are the large ones used only in the Sherman I Hybrid and the M4A1(76mm) (Sherman IIA), not in the Sherman I. (GUAAARGH - that should read "not in the Sherman II (M4A1)) How come all the alleged Sherman IICs are always picture from the frontal arc, always have the rear obstructed by cammo, luggage, tracks etc. while all the clear photos are Sherman IC Hybrids? Claus B [This message has been edited by cbo (edited 08-27-2000).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski: The US projectile tips look different than the German, the 90mm APCBC has a tip to rod diameter ratio of 9:1 compared to ~ 4:1 for german APCBC rounds while the HVAP shot is 14:1 like the british APDS and different from the german AP 40 type shots which are ~ 9:1 for the 75 and 88mm guns. <HR></BLOCKQUOTE> I am not shure how you calculate the tip to rod diameter or ogive radius but cross-sections of US 76mm and 90mm projectiles compared with the 7,5cm PzGr 39 shows that the penetrating cap of the German projectile is nearly flat while the actual projectile have a fairly shot but pointed nose. The cap of the US projectiles follow the nose of the projectile which is slightly longer than the German projectile. Unfortunately, I do not have a cross-section of the 8,8cm PzGr 39-1, but I would be surprised if it did not look like the other rounds with the blunt penetration cap. Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by Paul Lakowski: I was looking at Hunnicutts Pershing book and the 90mm ammo diagrams that Claus posted to the TANK NET. Claus could you post the link here?<HR></BLOCKQUOTE> Certainly. These are from papers provided by Robert Livingston: http://www.mobilixnet.dk/~mob75281/pic/diag/17pdrAPBCvelocity.jpg http://www.mobilixnet.dk/~mob75281/pic/diag/90mmHVAPvelocity.jpg http://www.mobilixnet.dk/~mob75281/pic/diag/90mmAPCvelocity.jpg While this is from Spielberger: "Panther..." http://www.mobilixnet.dk/~mob75281/pic/diag/75mmKwK42velocity.jpg Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by Durruti: Simon Fox posted some interesting stuff on British tank usage [snip] He seems to have pretty detailed sources - love to know what they are.<HR></BLOCKQUOTE> I am pretty shure that his source is http://www.geocities.com/MotorCity/8418/ Look under 21st Army Group Tanks. Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by DEF BUNGIS: Can someone explain why there are rounded muzzles on some barrels and on others there's just straight tubing.<HR></BLOCKQUOTE> I am not shure what you referring to, but in the case of the Firefly picture, the round thing at the end of the muzzle is the muzzlebrake. Some guns have it, others have not and it comes in all shapes and sizes. Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1: 17Pdr APDS @ 30^ Source: Hunnicutt's Sherman. 500yrds - 192mm 1000yrds 176mm 17Pdr APDS @ 30^ Source: CM Data 500ms - 190mm 1000ms - 190mm<HR></BLOCKQUOTE> You must have blinked, John - it is even worse : 500yds - 208mm 1000yds - 192mm 1500yds - 176mm Hunnicutt p. 565. Claus B [This message has been edited by cbo (edited 08-26-2000).]

<BLOCKQUOTE>quote:</font><HR>Originally posted by DEF BUNGIS: M haufbauer: Thanks for hosting the PIC. I guess it doesn't look to bad. Now the way I see it, the chassis looks smaller than the M4A1 chassis. Width wise. I dunno, i'm not an armorment expert. <HR></BLOCKQUOTE> Yes, thank for posting it. Even though it is difficult to see what the hell is under all that camouflage, it is evidently not a VC as it does not have the long hull of that vehicle. It does not look like a Sherman II though, the rear hull is much too "boxy" and the pronounced "peak" of the hull side near the turret looks a lot like the a welded hull Sherman or perhaps a IC Hybrid. I dont think this photo will rock the the armour community in its foundations Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1: Now can I have your opinion concerning the validity of the Wa Pruf Live fire tests of 8.8cm KwK.43 ammunition performance as used by Jentz etc, for 30^.<HR></BLOCKQUOTE> Frankly, I haven't got a clue. The fact is that no matter how you look at the numbers, the 8,8cm 0deg/30deg values are different from just about anything else. But they do not look like calculated data, the ratio goes up and down like other rounds do: 100 1,08 500 1,13 1000 1,11 1500 1,13 2000 1,14 Spielberger has a table on p. 253 in his Panther book showing penetration curves for the 7,5cm KwK 42 and the 8,8cm KwK 43. The odd thing is that while the curves for the 7,5cm shows both Panzersprenggranate and Panzergranate mit Stahlkern at both 90deg (0deg) and 60deg (30deg), there are only two curves for the 8,8cm: Panzersprengranate and Panzergranate mit Stahlkern at 90deg (0deg). If this table is a truthfull reproduction of the original source for the 8,8cm KwK 43 WaPrüf data, then it does not include 60deg data. It is difficult to form an opinion about, without having acces to the original data. What also puzzles me is that while calculated 30deg data for the 7,62cm PaK36r and the Soviet 85mm both uses the 1.23 30deg slope modifier that is straight out of the standard "Neigungswinkeltafel" found on my homepage, the 1.14 value seems odd. I recall Robert referring to the Germans using different tables for different velocities, so I wonder if the 1.14 value used in the calculated 8,8cm PaK 43 30deg data is the 30deg slope modifier found in another table, perhaps the one for 1000 m/s and beyond? Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1: What did the Febuary 45 US Army tests report that Robert gave you Claus?.<HR></BLOCKQUOTE> It is a long list of German pen data in inches, ranges in yards at 0deg and 30deg. The data is fragmentary, but for the 8,8cm KwK 43 the numbers available corresponds with the German data. It would be interesting if the CM people would post the 8,8cm KwK 43 APG test firing data that backs up their figures. OK, as I said before, I am not a math nut, half of what Paul and Andrew writes are miles above my head - I get the principle but rarely the technicalities. So bare with me if this is somewhat simplistic. First I tried to find out whether the 8,8cm data I have are test data or calculated data. It appears that WWII calculated data, at least the German variant, does not take T/D into account when calculating 30deg figures from 0deg figures. The ratio between the 0deg values and the 30deg values remain constant regardless of penetration. In the case of some German calculations of the Soviet 85mm gun, the ratio was 1.22-1.23. Looking at testdata for the US 76mm gun, the ratio goes from 1.32 to 1.17, for the 90mm from 1.27 to 1.20 and so forth. Here came the first surprise. Data found in Hogg and Senger und Etterlin forthe 8,8cm KwK 43 showed a constant ratio of 1.14 between the 0deg and the 30deg values while those from Spielberger (see below) varied from 1.08 to 1.14. I would suggest that this means that the 30deg data found in Hogg and Senger und Etterlin are calculated data, not real test firing data. Jentz only posts his 30deg figures, at least I've never seen the corresponding 0deg figures. However, in his book on the Panther, Spielberger shows both 0deg and 90deg figures for the Jagdpanthers 8,8cm PaK 43 gun, the original source being "Kraftfahrwesen e.V, Fachauschuss Wehrtechnik, Oberst a.D Theodor Icken". Icken was with WaPrüf 6. Spielbergers and Jentz 30deg figures vary only with a few mm and both apparently comes from WaPrüf, so I assume they are likely to come from the same source. Here comes the funny part: Spielbergers figures for 0deg are: 100 - 220 500 - 205 1000 - 186 1500 - 170 2000 - 154 CMs figures for 0deg are: 100 - 220 500 - 205 1000 - 188 1500 - N/A 2000 - 157 So the German wartime data for penetration at 0deg is not in conflict with CMs data. It is in the calculation of the slope effect at 30deg that things go wrong. Spielbergers figures for 30deg are: 100 - 203 500 - 182 1000 - 167 1500 - 150 2000 - 135 CMs figures for 30deg are: 100 - 177 500 - 165 1000 - 151 1500 - N/A 2000 - 121 The relationship between Spielbergers 0deg and 30 deg figures range from 1.08 to 1.14 while CMs range from 1.24 to 1.30. Looking at the 76mm, 90mm and 17pdr they all have a ratio between 0deg and 30deg around 1.20 to 1.30 while the 8,8cm KwK 43 is down at 1.08 to 1.14 and thus appears to be less effected by slope. Why? Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by Spook: Thanks, DEF. Up 'til now, I didn't realize that the Firefly IIC was made up to be a hen's-teeth issue in its field usage. The B&W photo will show just enough camoflauge (foilage) attached to keep the issue contentious for some. But after repeated study of the hull lines, my own assertion of the tank being a IIC still stands.<HR></BLOCKQUOTE> Believe me, in the tank nut crowd, this could be like pissing in the punch bowl Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by PzKpfw 1: Wow Claus, good to see you. . <HR></BLOCKQUOTE> You too John You mentioned that "Aberdeen data" backed the CM results. What exactly is "Aberdeen data"? Is it posted somewhere in this thread? I have some of Roberts data from a US Army February 1945 report, but this does not support the CM figures. Thanks for the CM 0deg figures, I'll go type them in and see what happens... Claus B

<BLOCKQUOTE>quote:</font><HR>Originally posted by Spook: So I had to make the distinction by visual inspection. The Firefly on pg. 60 makes use of applique armor which breaks up the vehicle outline in that picture, but for that case, I'm more inclined to label that vehicle a IC Hybrid. The one on pg. 61 (with snow camo and side-mounted logs) can't be discerned right off as one or the other. But on the picture in pg. 51, in spite of the loosely-applied camo, I can state with much more certainty that that is an M4A1 hull (NOT the Hybrid hull) given the back-hull rounding & curvature. If so, then it is the Firefly IIC.<HR></BLOCKQUOTE> Any change that you (or anyone else with the book) could scan and post the IIC photos? I believe it is generally recognized today that during the war only the IC, IC Hybrid and VC were built. The IVC was a one off when the US Army played around with the possibility of using the M4A3 for Firefly conversions to the US Army and the IICs are postwar museum mixups (like the Grizzly version) or one-off experiments. If there really is solid pictoral proof of the IIC in operation in WWII, I think it will ruffle a few feathers Claus B

First of all, I am not math nut and I do not (currently) play CM but the discussion about the 8,8cm KwK/PaK 43 penetration being either "doctored", obtained under circumstances different from other German data etc. is interesting. I do have a couple of questions I hope someone can answer. 1: Are there any WWII-era test data that backs up the results of the CM formula for the 8,8cm KwK 43? 2: If so, are there similar results obtained under the same circumstances for the 7,5cm PaK/KwK 40 and KwK 42 and do these correspond with the results of the game formula for these guns? 3: What are the CM penetration data for the 8,8cm KwK 43 L/71 at an angle of 0 degrees at 100m, 500m, 1000m, 1500m and 2000m? I went over whatever data I had for the KwK 43, most of it originating in WWII primary sources. While most of it appears very similar, there are some destinct differences in the penetration curves that the numbers produce, which seems to indicate that some of it is not actual firing data, but rather calculated data using some form of simplified formula (compared to both the CM formula and what others have posted). Claus B