rexford Posted January 9, 2001 Share Posted January 9, 2001 CM slope effect for 76 HVAP vs 47mm armor at 60° is 2.1, U.S. test data results in 4.3 estimate. CM also shows HVAP slope multiplier changing with T/D, firing test data shows that it remains constant. Panther glacis resistance to 76 HVAP will be about twice what CM predicts, 55° slope effect for HVAP should be 3.3. This is something else that needs fixin'. Link to comment Share on other sites More sharing options...
Forever Babra Posted January 9, 2001 Share Posted January 9, 2001 LOL... I'll bet they have their hands twitchin' toward the ban key by now... You don't have to find ALL the faults y'know Link to comment Share on other sites More sharing options...
dog6880 Posted January 9, 2001 Share Posted January 9, 2001 umm.. so can my shermi kill that tiger at 500 meters? one day someone has got to explain all that stuff about 60 degrees and slop mutifier... Link to comment Share on other sites More sharing options...
Bastables Posted January 9, 2001 Share Posted January 9, 2001 Bugger, my poor Fireflys and their APDS. Link to comment Share on other sites More sharing options...
rexford Posted January 9, 2001 Author Share Posted January 9, 2001 Just about run out of things to say. Would like game to be about the same as our rules, cause it is easier to play with computer tanks, infantry and scenery than maneuver scale models on my bed and then have a stray infantryman stick into my back late at night. Link to comment Share on other sites More sharing options...
rexford Posted January 9, 2001 Author Share Posted January 9, 2001 APDS slope effects might be close to HVAP. Plus about half of APDS shots might go astray and lose penetration due to uneven shed of sabot pieces. Link to comment Share on other sites More sharing options...
Bastables Posted January 9, 2001 Share Posted January 9, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by rexford: APDS slope effects might be close to HVAP. Plus about half of APDS shots might go astray and lose penetration due to uneven shed of sabot pieces.<HR></BLOCKQUOTE> Thats what I thought too glad you're with us Rex Link to comment Share on other sites More sharing options...
rexford Posted January 9, 2001 Author Share Posted January 9, 2001 We use U.S. HVAP slope effects for all tungsten core, since tungsten brittleness makes slope multipliers greater than steel. Link to comment Share on other sites More sharing options...
Dan Robertson Posted January 9, 2001 Share Posted January 9, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by rexford: We use U.S. HVAP slope effects for all tungsten core, since tungsten brittleness makes slope multipliers greater than steel.<HR></BLOCKQUOTE> From some data I got from Britwar site I found that the modifier for APDS over 30 dregrees is (Cos Angle)^(2/1.1) under 30 (Cos Angle)^(2/1.37) and over 30 degrees for a modern tungsten alloy APDS (ie 105 and 120) (cos Angle)^(2/1.25) BTW the I am looking at the velocity curve for APCR, in the game it seems that they have far too great penetration at the muzzle and then drop off at too greater weight, I haven't looked into it yet fully though. Link to comment Share on other sites More sharing options...
Dittohead Posted January 9, 2001 Share Posted January 9, 2001 Sounds good to me. Link to comment Share on other sites More sharing options...
Mr. Clark Posted January 9, 2001 Share Posted January 9, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by Forever Babra: LOL... I'll bet they have their hands twitchin' toward the ban key by now... B]<HR></BLOCKQUOTE> LOL! That's hilarious... and probably true! But seriously, I'm incredibly happy to have as many hard core Grogs here as possible to answer all my random Q's. Link to comment Share on other sites More sharing options...
Monte99 Posted January 9, 2001 Share Posted January 9, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by rexford: We use U.S. HVAP slope effects for all tungsten core, since tungsten brittleness makes slope multipliers greater than steel.<HR></BLOCKQUOTE> I keep hearing the voice of HAL... Link to comment Share on other sites More sharing options...
Marlow Posted January 9, 2001 Share Posted January 9, 2001 Opps. Sorry, wrong thread. [This message has been edited by Marlow (edited 01-09-2001).] Link to comment Share on other sites More sharing options...
WolfLord Posted January 9, 2001 Share Posted January 9, 2001 This probably explains why ONE Sherman 76 took out 3 of my HULL-DOWN Panthers! Arrrggggg!!! Ok, I feel better. Link to comment Share on other sites More sharing options...
Tiger Posted January 9, 2001 Share Posted January 9, 2001 I read about tests conducted by the US army in Isigny France of 76mm HVAP vs 6 captured Panthers' front glacis plate. No penetrations were acheived at ranges over 300 yards (274.3m). John Link to comment Share on other sites More sharing options...
rexford Posted January 10, 2001 Author Share Posted January 10, 2001 At Isigny France, 8 hits by APDS at 400 yards on Panther glacis, 1 penetration. 76 HVAP penetrated Panther glacis at 200 yards, 1 penetration in 6 hits on glacis. Panther glacis resistance is 80 x 3.35 slope effect, or 268mm at 0°. 76 HVAP penetration is 227mm at 0°, penetration/resistance ratio is 227/268, or 0.85. Combination on low quality armor and low probability penetration resulted in 76 HVAP penetration. CM slope effects for HVAP would seem to warrant re-examination. Link to comment Share on other sites More sharing options...
Olle Petersson Posted January 15, 2001 Share Posted January 15, 2001 Which HVAP are we discussing? There are many different aspects on which ammo that is best at penetrating sloped armour, there was one (full calibre) round developed for the US 90mm gun that had far better performance against the Panther frontal armour than the British 17pdr APDS, while it fared much less against vertical armour... Read all about it at Sub-calibre ammunition. ( http://www.wargamer.org/GvA/background/ammotypes6.html ) Cheers Olle ------------------ Srategy is the art of avoiding a fair fight... Link to comment Share on other sites More sharing options...
Simon Fox Posted January 15, 2001 Share Posted January 15, 2001 Yea, right Olle, and British sub-calibre ammunition was not 'the same' as HVAP in fact it was much better which is reflected in the latest patch as they are not shatter prone. Certainly APDS rounds are less accurate at longer ranges due to problems with the sabot but I can't see this affecting penetration since they are unlikely to hit the target. I am happy to be convinced but the exceedingly condensed proclamations of the mysterious 'we' are falling a wee bit short so far. Maybe I should insist that BTS model the plugging effect of non-penetrating hits on face hardened armour causing catastrophic internal damage to the vehicle and it's occupants. Or even the increasing chance of penetration under certain circumstances when the projectile shatters. ------------------ Muddying the waters as usual. Link to comment Share on other sites More sharing options...
Ari Maenpaa Posted January 16, 2001 Share Posted January 16, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by Olle Petersson: There are many different aspects on which ammo that is best at penetrating sloped armour, there was one (full calibre) round developed for the US 90mm gun that had far better performance against the Panther frontal armour than the British 17pdr APDS, while it fared much less against vertical armour... Cheers Olle <HR></BLOCKQUOTE> David Michael Honner’s excellent site states that Pershing’s 90mm M3-gun had an APC M82 (late) ammunition which could penetrate Panther’s glacis up to 1006 meters. Regular ammunition could only do so at up to 411 meters, due to the different effects of slope on the two types of projectile. However this "better" projectile was in shortage and according to same source, only few rounds reached the troops in time for use in World War II. And there is only ONE type of US76mm HVAP (M93) mentioned so no change of misconceptions there. Same thing about 17pdr APDS shot. <BLOCKQUOTE>quote:</font><HR>Originally posted by Simon Fox: Yea, right Olle, and British sub-calibre ammunition was not 'the same' as HVAP in fact it was much better which is reflected in the latest patch as they are not shatter prone. Certainly APDS rounds are less accurate at longer ranges due to problems with the sabot but I can't see this affecting penetration since they are unlikely to hit the target. I am happy to be convinced but the exceedingly condensed proclamations of the mysterious 'we' are falling a wee bit short so far. <HR></BLOCKQUOTE> Hmmm. I find Rexford’s "proclamations" to be well based. Mysterious 'we' doesn't bother me at all because his/their conclusions are backed up with cold facts. According to the Isigny tests 17pdr APDS was VERY inaccurate. 42 rounds of 17pdr SABOT were fired and only 57% (24 rounds) were hits at target at 200 - 800 yards range. The target was Panther’s glacis plate and 7 rounds missed the whole tank. Of 13 shots fired from 200 - 300 yards only 7 hit the glacis. And this happened in test conditions. I find it stunning. It’s hard to believe those shots to hit anything beyond 1000 meters in battle conditions. The testers themselves made a conclusion: 17pdr SABOT of the lot tested is considered an unsatisfactory ammunition because of its inaccuracy. They also concluded that the 17pdr APCBC and the 76mm HVAP, T4 are considered the best antitank ammunitions available in these calibers for use against heavy armor. The 17pdr APCBC is somewhat superior to the 76mm HVAP, T4, against the Panther Tank. NEITHER one can be be depended upon to penetrate the glacis plate of the Panther in one fair hit on average quality plate. I made a test with CM 1.1: Firefly VC against dug in Panther at 1000m range on open ground. I changed FF's ammo load from regular AP to tungsten between tests. To begin with the hit percentage with tungsten ammunition was better (29%) than with normal Aps (27%). My tests confirmed that in CM Firefly's 17-pdr APDS ammunition doesn't suffer from any kind of accuracy penalty compared to regular AP-ammunition. Ari Link to comment Share on other sites More sharing options...
PzKpfw 1 Posted January 16, 2001 Share Posted January 16, 2001 Good post Ari I was going to point out the poor LF 17lb round results from Isigny as well. Regards, John Waters ------------------ "We've got the finest tanks in the world. We just love to see the German Royal Tiger come up on the field". Lt.Gen. George S. Patton, Jr. February 1945. Link to comment Share on other sites More sharing options...
rexford Posted January 17, 2001 Author Share Posted January 17, 2001 17 pounder APDS slope effects are less than 76 HVAP, and 90 HVAP slope multipliers very close to 76 HVAP at higher angles. Jentz states in his book, the one that includes tests against Tiger I by British, that APDS was "not especially accurate" (it's on page 12, but I lost my notes regarding the book title). If accuracy is bad then penetration is also bad because both are related to irregular flight path (with wobbles). 17 APDS should penetrate Panther glacis out to 1200m WITHOUT the 0.85 quality factor, if British 30° penetration figures are converted to 55° using British slope effects. At Isigny they failed at unbelievably close ranges. WW II APDS is not consistently accurate, and Jentz goes further and states it was "not particularly accurate" and had trouble against the Tiger II front lower hull (which should have been penetrated at 1300m, based on comparisons using APDS slope effect at 50° and 0° penetration by 17 pdr APDS). Panther glacis resistance at 1.00 quality is 80 x 2.75 for 55° to 0°, or 220mm at 0°. 17pounder APDS penetration at 0° works out to be: 256mm at 500m 233mm at 1000m 223mm at 1250m 213mm at 1500m These are highest British estimates (converted 30° to 0° using 1.24 multiplier). Following are reduced British estimates found in alternate source: 230mm at 500m 217mm at 750m 205mm at 1000m Tiger II has 100mm at 50° front lower hull, resists APDS penetration like 220mm at 0°. Jentz book suggests that when 17 pdr APDS fired at Tiger II, penetration way off test results. Similar to Isigny. Link to comment Share on other sites More sharing options...
Dittohead Posted January 17, 2001 Share Posted January 17, 2001 From http://www.britwar.co.uk/salts/salt6.htm Lots and lots of good info on this site. WO 291/1263, "Firing Trials, 17pdr Sherman." "Table VI has been constructed which shows the probability of a hit on a target 5' wide by 2' high (representing a Panther turret) at various ranges using both types of round." Range(yds)APC% AP/DS % 400/ 90.5/ 56.6 600/ 73.0/ 34.2 800/ 57.3/ 21.9 1000/ 45.3/ 14.9 1500/ 25.4/ 7.1 Comments and corrections These assume that the MPI is placed centrally on the target. The trace from the AP/DS round was not seen in 73% of cases by a flank observer, and in no case from inside the tank. Link to comment Share on other sites More sharing options...
Simon Fox Posted January 17, 2001 Share Posted January 17, 2001 <BLOCKQUOTE>quote:</font><HR>Hmmm. I find Rexford’s "proclamations" to be well based. Mysterious 'we' doesn't bother me at all because his/their conclusions are backed up with cold facts.<HR></BLOCKQUOTE> I disagree. Irrespective of the value of the contributions of the conglomerate entity known as Rexford (which I happen to think are excellent) the methodology of presentation is extremely brief. Do you find these "proclamations" to be "well based" because they agree with your opinions based on your knowledge? Certainly they are seldom presented with any supporting evidence, although admittedly with some prompting this can be forthcoming. There is no such thing as "cold facts", merely evidence of one form or the other which may or may not support a point of view depending on the nature of the interpretation. Slapdragon has made some good posts on precisely this subject (though how he came by this knowledge in his professional capacity is incomprehensible to me ). This is precisely why I bumped this thread by kip anderson http://www.battlefront.com/discuss/Forum1/HTML/011166.html which is a great example of a well reasoned, structured and supported argument even if you don't agree with it. Isigny anybody would think it was the only test done or that the results were universally suprising. It is fairly common knowledge that 17lbr APDS was less accurate than APCBC. I was talking about real life in my post not CM. I assumed this was modelled in CM but if it was not it should be. The only problem with this was the incremental improvement in allied sabot rounds through this period which seems fairly poorly documented and therefore difficult to model. Also some sources suggest the British APDS was a little better in this regard than US HVAP. Well dittohead has beat me to it and posted the British data but note also WO 291/762, "Accuracy of APCBC/HV shot and AP/DS when fired from the 6-Pounder Gun mounted in the Churchill IV." My inclination from these and other data is that APDS doesn't suffer to badly vs APCBC in accuracy out to about 500m but beyond that it does. Even so the proviso exists that the date of these tests may be 1943 and it is not entirely clear what "ranging rules" were used. Certainly I have read that APDS is more accurate if bracketing is performed with that round rather than APCBC (if you have enough of course ) The British were well aware of the difficulties the highly sloped Panther hull plates would cause them even with the 17pdr when Soviet reports of this tank prompted them to test at angles greater than 30degrees: WO 185/118, DDG/FV(D) Armour plate experiments. . "...but recent trials have shown that a 75mm plate at 53º can only be holed at point blank range by 17 pdr APC and that the 17 pdr APCBC will not defeat the plate at any range." British postwar data might prove useful in this discussion since they seem to have started to test at up to 60degrees and many of these weapons were still in use. [This message has been edited by Simon Fox (edited 01-16-2001).] Link to comment Share on other sites More sharing options...
rexford Posted January 17, 2001 Author Share Posted January 17, 2001 Many times my posts state results and leave things at that. Other times they fully document the case,a nd sometimes they beat it to death. It is difficult to be at the same level for alot of posts. Did you read what Jentz said about APDS accuracy? About Isigny? We had other firing test results from WW II British sources on APDS dispersion, and it seemed to easily be the most inaccurate ammo used during WW II. At Isigny they aimed at the Panther glacis and missed the entire tank. Soviet T62's were the first to use armor piercing fin stabilized discarding sabot rounds, smootbore gun so stabilization in flight came from fins that came out after ammo left barrel. Israeli's noted after 1973 war that many T62 shots came at them sideways!!!!!!!! Discarding sabot of any kind goes thru a long development period. Link to comment Share on other sites More sharing options...
Basebal351 Posted January 17, 2001 Share Posted January 17, 2001 <BLOCKQUOTE>quote:</font><HR>Originally posted by rexford: CM slope effect for 76 HVAP vs 47mm armor at 60° is 2.1, U.S. test data results in 4.3 estimate. CM also shows HVAP slope multiplier changing with T/D, firing test data shows that it remains constant. Panther glacis resistance to 76 HVAP will be about twice what CM predicts, 55° slope effect for HVAP should be 3.3. This is something else that needs fixin'.<HR></BLOCKQUOTE> So, what you're saying is that Panthers are even awesomer??? That's all you had to say. No need for fancimication by datafying us all with numbers and whatnot. Simple slogans should do the trick... "Forget the Velocity and the Mass, Panthers Should Just Kick More A.." -Rexford ------------------ "...you're just jealous that the UK didn't get to join the war before the Americans took Berlin. But, I WILL give credit to where credit is due. If it wasn't for America's almighty industry, we might not have been able to win the war single-handedly. You UK-landers would have been the first people we would have called, though, if we needed some help... or some more tea. We promise." Link to comment Share on other sites More sharing options...
Recommended Posts