Jeff Duquette
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Posts posted by Jeff Duquette
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More excellent work Slap. Thanks for sharing your findings and insights.Originally posted by SlapHappy:The building models as currently implemented in the game are basically textured solid shapes without voids for windows and doors. While it would be easy enough to create new models which had these voids, there is obviously a lot more involved in making them interactive with troops and creating the LOS requirements for the game. Right now, even if it were possible to place a soldier inside one of the building models, he couldn't get out of it. It would be a cell.
Based on what I know about 3-D modeling (which is basically not much), there are two different ways to approach soldiers in buildings.
Firstly, you could have a free-form method which would allow troops to move freely around inside the "cavities" of the buildings, restricted only by any solid objects like interior walls and such. The problem with this method would be a more complicated LOS procedure for spotting a human entity through a window or door. Not only proximity to an opening, but angle and percentage of enemy exposed would have to be considered to be realistic in such a system. If you plan on implementing multi-story buildings, the problem becomes even more complex as you have to factor in height to target-defender relationships. How much of the sniper who is crouched at the second-floor farmhouse window can be seen? And at what angle based on the relative height and body position of the firing element? Interesting stuff. And not easy to pull off convincingly I bet.
The second, and seemingly easier method would be to define fixed "crew" positions within the building that allow you to post soldiers at particular defined areas where they can achieve spotting. In such an arrangement, of course, the only way to "hide" in the building would be to allow the troops to still achieve a prone position. Or perhaps crouch position for windows set at upper torso-head positions. One downside of this system might include artificially limiting the number of troops allowed inside the building as defined by it's number of "crewable" portals.
I think it's at least fairly likely they will take the 2nd approach to enterable buildings as it fits nicely with the current vehicle modelling system and permits the designer to simply treat the building as a more complex version of their fortification model.
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For the track throwing thing, high explosives are used by combat engineers as cutting charges for rail road tracks, bridge trusses, etc. So explosives can cut construction grade steel. But fuzing, direction of the blast wave and explosive tamping are all crucial to maximizing target effects or target cutting potential.
Hardened nickel steel -- ala armor steel -- is a considerably tougher material to cut with explosives. Normally line shaped charges are used for this purpose. But track links and pins, road wheels, sprockets, etc are perhaps more vulnerable to the kinetic energy of a direct hit, or blast or splinters. Optics and antennas are also vulnerable to splinters.
But again target effects of HE-shell fire vs. tanks are more typically suppression. Get the vehicles to button up. I don’t think the ToW game in its present form distinguishes between a buttoned up tank and an unbuttoned tank. Of course M-Kills (mobility-kill – be this track related damage or engine related damage) and F-kills (fire power kill – be this optical damage – gun tube damage etc) are always possibilities as are K-Kills (catastrophic kill). It's just that the statistics don't jive with these effects being particularly prevalent. Again, it is why modern artillery has resorted to munitions such as copperhead or ICM. It bumps artillery capability vs. AFVs from one of suppressive effect to one of target destruction.
As with tactical air support, HE shell fire is at best only marginally effective at killing tanks. Does that mean tanks were not killed by TAC air or HE shell fire – no.
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Slap:Originally posted by SlapHappy:Emails fine with me, mines posted in my profile.
Sorry -- works got me swamped. But yes, let's kick this around a bit. I'll send an email today as a commo check.
Jeff
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Hi Slaphappy:Originally posted by SlapHappy:Jeff
So any suggestions for "normalizing" the HE performance against armor given the fairly simplistic modeling used in the game. Is there one shell type that could be used to extrapolate the performance to be applied to other ammos types?
Given that there is only one type of HE listed for each gun, does that seem like a reasonable approach?
Sort of similar to the approach you used when modeling the 50L42 for Oudy's mod tank....
Yes, I think so. I just had to do this several months back for one of the Steel Beasts designers. He was interested in similar information, but of course much more modern ordnance. Let me look it over and I'll forward along the results. Perhaps we should do this via a few emails?
Best Regards
Jeff
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While this is far removed from the actual topic\subject, I suppose this might be interesting to some folks here. Regarding the Battle of the Bulge being a major killing ground for Allied Tactical Air Attacks, a similar operational study as that I described above for the Mortain counterattack was conducted throughout the vicinity of salient by a joint group of Americans & British in January of 1945. This was conducted under the auspices of No.2 ORS Group. They were of course very interested in proving the efficacy of modern tactical air support and his ability to shape ground combat results. The group examined 101 German Tanks, self-propelled guns, and other "light armored vehicles". Of this total, four panzers, one SP-gun and one Lt AFV were identified as definite air-to-ground related kills. One SP-Gun examined had both a air to ground rocket hit and an AP penetration. Assuming the second SP was killed by the air to ground rocket, that would put the air to ground tank kill percentage at slightly less than 7%.
High Explosive Shells killed 3 Panthers, 1 Sp-Gun, and 4 Light AFVs. That's a total of eight HE shell kills; a little less than 8% of the sample attributable to HE shell fire.
Abandonment + Demolition accounted for 39-armoured vehicles. The rest were killed by AP.
See No.2 ORS 2nd TAF Joint Report No.1 "Air Attack on Enemy Amour in the Ardennes Salient, Operational Research in Northwest Europe."
[ June 13, 2007, 08:19 PM: Message edited by: Jeff Duquette ]
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So if I understand you properly, Jeff, you would suspect .2 or .3 calibers for most HE roundsOriginally posted by SlapHappy:</font><blockquote>quote:</font><hr />Originally posted by Jeff Duquette:
This is pretty simplistic as I am guessing impact velocity will tweak these numbers up or down. Moreover OF-412 is a pretty high velocity HE round, but perforation of about 0.2 to 0.3 calibers is about the ballpark for HE vs. steel armor. This isn't completely from the hind quarters. Having looked over a bit of ballisitic test material for CPC and semi-armor piercing projectiles it's apparant that this form of shell will do about 0.45 to 0.65-calibers of armor perforation. But of course CPC and semi-armor piercing are a bit more like AP-shell design in that these things employ a heavily thickend solid nose section and base fuze rather than no nose section and a relatively fragile PD fuze.
Best Regards
Jeff
or 100mm x .2-.3 = 20mm to 30mm penetration?
But in the case of the heavy, higher than normal velocity OF-412 you would say .45 to .65 calibers or:
100mm x .45-.65 = 45mm to 65mm penetration?
Or am I off by a decimal place?
In any event, what it does make me wonder is how the RPG-40 (non-heat) grenade manages to penetrate 20mm of armor (at least by several sources) without having anywhere near the velocity of an HE cannon round and lower projectile mass as well?
I'm trying to "normalize" the HE effects on armor in the game and am having a rough time doing so because of lack of available information sources. </font>
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Originally posted by GoodGuy:
[QB]
It is in Jentz. See page 133 of Jentz’s “Panther Tank, The Quest for Combat Supremacy”.Below is an excerpt from a report on the Operations of the Panzer (Panther) Regiment von Lauchert by Guderian following Kursk. The passage of interest:
“Armor. Enemy weapons did not penetrate through the frontal armor of the Panther. Even direct hits from straight on fired from 76mm anti-tank and tank guns did not penetrate through the gun mantlet. However, the sides of the Panther were penetrated at ranges exceeding 1000-meters. The 76mm antitank and tank rounds broke cleanly through the turret sides and both the sloped and vertical hull sides. In most cases the Panther immediately caught fire. This was possibly due to the large amount or propellent in the ammunition that is carried.
The Panther is basically invulnerable to artillery fire. However, direct hits by calibers of over 150mm on the roof of the hull and turret had the effect of deforming the armor and causing internal damage. Hits by light caliber shells hitting the commanders cupola and the roof armor showed no effect.”
The roof armor revisions were not made -- thickening of the roof armor that is -- at least according to the official response to Guderians report because the Panther's suspension was inadequate for the heavier loading entailed. See page 134 same Jentz title.
Actual operational studies conducted during the war suggest only rather limited success on the part of tactical air vs. armored targets. Typically K-Kill counts attributable to TAC air were invariably less that 10% of all tanks destroyed. But than I already said this earlier on. Of course the best example of this was the Mortain counterattack in which a huge amount of in theater tactical air was dedicated to air to ground attacks against German armored attacks.The British, having contributed a large number of sorties to this particular endeavor, sent in a number of Operational Research Teams to conduct "AFV body counts" in the area encompassing Mortain operation. Again the tank K-Kills attributable to this rather intensive use of tactical air was only about 10% of all Panzers KO’d during the counterattack. Again most panzer's were KO's by Kinetic Energy projectiles.
Undoubtedly we can all lay our hands on reports detailing such-and-such tank being destroyed in such-and-such manner. Like a Tiger tank being abandned as a result of a frontal hit from a 6-pdr. The point is of course to look at the larger picture. What does the statistical data tell us about how tanks were typically be destroyed. Again the overall numbers of tanks being killed by high explosive shells is a relatively small percentile of all tanks being destroyed. Again the biggest killer was of course kinetic energy projectiles -- AP. No big surprise. -
Does the game include Haft-Holladung (spelling?) magnetic antitank mines?
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Looks great Oudy!
The invisible portions of the Firefly barrel -- is this some sort of texture issue and the background color of the game’s encyclopedia screen? It looks like there is a camouflage scheme on the 17-pdr barrel. Do the same portions of the barrel disappear during actual game play, or is this only occurring in the game’s encyclopedia screen?
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I agree. Rather than assigning the player an on map Hummel or two for a scenario, give the player a couple of indirect fire missions. I have no idea why the designers would include this vehicle in a game of this scale when other more appropriate AFVs could have been included in the unit mix. Like an 105mm Sturmhaubitze 42 or 105mm Assault gun Sherman, or 88mm Flak 18/36 gun, etc.Originally posted by Kudos:Well Hummels and Wespes are not good anti tank and a waste of time on the pitch but.... If you can have them in reserve then you should be able to call in some fire support. The aiming u say is right but with infantry you should be able to gain eventual decent arty fire and no miles off. Like When I call in arty from off map, there should be some shells that come in as rangers then u give correction and say fire for effect at which point all hell breaks loose. That is true arty... I know all games can not be perfect but if I can not use Hummels or Wespes to good effect then we should knock them on the head and exclude them from the game...
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Yes, the small map size and minimum range of say a Hummel is partly an issue. Although I suppose you could in theory have a Hummel parked at the very edge of one of the bigger maps and be able to come up with the right charge and gun elevation solution to plop a shell onto the far half of a map. Like a howitzer firing charge one at max elevation, or a mortar battery.
But to add to the map size restrictions, inherent round to round dispersion, danger close etc, indirect fire within a game of this tactical scale should be abstracted – as it already is. The problem with allowing a Hummel or the like to use indirect fire in a game of this scale is that before indirect fire can be employed the location of the gun or battery has to be established via surveying – both X & Y coordinates as well as the guns altitude (elevation). Back in those days there were no GPS systems or satellites and such. Artillery crews had to be psudo-surveyors as well as artillerists. An Aiming circle needs to be setup, aiming stakes need to be placed. The gun crew needs to very accurately establish what its actual location is in X, Y, and Z coordinates. This information needs to be relayed to the fire direction center (FDC). While not always the case, typically a forward observer (FO) needs direct observation on the target. His position also needs to be known by the FDC. The FO needs to guesstimate the position of the target and feed this information to the FDC. The FDC than figures out the location of the target in X, Y, Z coordinates relative to the position of the FO. The FDC than needs to determine an appropriate firing solution for the gun or battery or battalion or whatever level of unit is going to do the indirect fire mission. This will be a function of the guns positions, the FOs position and the Targets position. Than the FDC can than establish range, deflection and altitude for the gun and target line and determine propellent charge. Adjustments are made for a number of variables – propellant temperature, gun barrel ware, air temp, humidity, non-rigidity of trajectory for large contrast in altitude between the gun and target line, etc etc – even curvature of the earth if the range is great enough. Of course there will than follow a series of spotting rounds or adjustment shoots while the FO + FDC “walk” the fire onto the target. The details associated with different army’s could be a tad different than the above. But in general these are some of the reasons what players could not realistically employ indirect fire with on map guns.
Players constantly want to move their Hummels or Wespes about. Each time they are moved, the aiming circle would need to be broken out, aiming stakes set, position of the gun reestablished, etc. I think the only intent of having these vehicles in the game is for use in direct shoots only. The games present indirect fire mission format is much more appropriate to this scale of game than allowing players to utilize indirect fire for Hummels or Wespes or whatever. I suppose one might be tempted to add FOs or FOOs to the game.
The manner in which indirect fire is currently used in the game seems OK to me. It's not the best system, but it is a reasonable approach and a good compromise given some of the complexities of indirect fires.
[ June 10, 2007, 08:21 AM: Message edited by: Jeff Duquette ]
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Hi Oudy:
What Nev403 said. Just to add a bit the US 12th Army Group began pressing the British to begin sending them 17-pdr Firefly’s a couple months into the campaign in Northwest Europe. According to the 12th Army Operations reports a handful did end up being shipped over to the Americans.
As to your new very nice(!) vehicle edit -- The error isn’t on your part. The Challenger, Archer and Firefly should all be using the same penetration values (and if someone were to make a mod with the Achilles -- M10 TD with 17-pdr -- it should be using the same gun and penetration values as Challenger\Archer\Firefly). The problem is that the game is showing one set of penetration values for the Challenger and another for the Archer. Both should be the same.
The Comet was equipped with the 77mm, and would have lower penetration values than the gun on the Archer\Challenger\Firefly\Achilles.
Knowing what I know thus far about how the game seems to be modeling slope effects, I think the Archer’s penetration values represent a better guesstimate for your Firefly mod. However, the same penetration values for the Archer should also be utilized by the Challenger.
ToW values for Archer’s 17-pdr APC @ 0-degress
100m = 172mm
500m = 162mm
1000m = 150mm
1500m = 136mm
2000m = 124mm
NOTE: These are not actual 17-pdr penetration values @ 0-degrees, however if you are trying to maintain consistency within the games engine the above would be the values you would use.
Best regards
Jeff
[ June 10, 2007, 08:31 AM: Message edited by: Jeff Duquette ]
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Very good point. I have had the same issue with infantry in built-up areas. It's almost as if tanks can get around built areas easier than infantry. Moreover tanks can plow right through fences and walls -- conversely infantry has to circumvent these obstacles.Originally posted by SlapHappy:The wall graphics also leave a lot to be desired. On many of the maps, the walls are slightly taller than man-height, and since infantry can't scale them, foot units are forced into streaming "around" these obstacles into the narrow openings represented by gates and such. Along with the enterable buildings, I think it would be nice to add in the extra coding and animations to allow infantry some obstacle scaling capabilities.
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Nice Oudy!
How come your not using the penetration figures listed for the Archer?
Jeff
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Oudy:
Sprengrante muzzle velocity for the 50mmL42 was 450m/s. Weight of the spgr shell is listed as 1.85Kg. Bursting charge is pretty much the same as the L60 so effective fragmentation between the two guns spgr rounds is probably a wash (same).
There are a couple errors in the games listed data that I spotted while plugging and chugging. There should be no difference in weight between the pzgr-39 APC projectiles for the 50mmL42 and 50mmL60 guns. They should both be 2.06Kg. My game shows the L60’s pzgr-39 weight as 2.08kg.
I couldn’t find any information on rate of fire for either the L42 or L60. The L42 pzgr-39 cartridge is of course lighter and perhaps 5 or 6 inches shorter than the L60 pzgr-39 cartridge. I suppose in theory, this would allow a loader to load a bit quicker. Although loading rate is also a function of the ready rack arrangements, amount of room in the fighting compartment, etc. Firing rate is often more related to the gunner and his ability to lay the gun on its target than the speed of the loader. I think it would be reasonable to leave the rate of fire the same as that of the L60; or it is also probably reasonable to increase the rate of the L42 over that of the L60 by perhaps 1 or 2 rounds a minute. What is the game’s listed ROF for the L60?
I also dug around a bit more in my bookshelves and these are the more typical penetration figures one comes across for pzgr-39 fired by both the L42 and L60.
50mmL42 firing pzgr-39 @ 0-degrees
100meters = 73mm of RHA
500meters = 59mm
1000meters = 45mm
1500meters = 34mm
50mmL42 firing pzgr-39 @ 30-degrees
100meters = 53mm of RHA
500meters = 43mm
1000meters = 32mm
1500meters = 24mm
50mmL60 firing pzgr-39 @ 0-degrees
100meters = 95mm of RHA
500meters = 78mm
1000meters = 57mm
1500meters = 35mm
50mmL60 firing pzgr-39 @ 30-degrees
100meters = 67mm of RHA
500meters = 57mm
1000meters = 44mm
1500meters = 34mm
Sources can vary by a couple mm’s here and there.
As you indicated above the ToW data for the 50mmL60 pzgr-39 are as follows:
50mmL60 firing pzgr-39 @ 0-degrees
100meters = 80mm of RHA
500meters = 68mm
1000meters = 54mm
1500meters = 42mm
These are of course much lower than what one normally sees for the 50mmL60. However, it appears to me that ToW 50mmL60 figures are based upon typical perforation values one sees for the L60 @ 30-degrees and subsequently bumped up to the 0-degree values by using a uniform slope effect multiplier of about 1.2 for 30-degree obliquity. For example the figures I reported above for the L60 are from the Dattenblatte for the 50mm KwK-39 L60 firing pzgr-39. These are also consistent with the figures reported by Jentz in “Tank Battles in N. Africa”. Which probably implies Jentz got his numbers from the original Dattenblatte for the 50mm KwK-39 L60.
For example Jentz & the Dattenblatte figures for 50mm KwK-39 L60 firing pzgr-39 at 30-degrees multiplied by 1.2 are:
50mm KwK-39 L60 firing pzgr-39 @ 0-degrees.
67mm x 1.2 = 80.4mm
57mm x 1.2 = 68.4mm
44mm x 1.2 = 52.8mm
34mm x 1.2 = 40.8mm
These look reasonably close to the ToW values for the L60 -- close enough for government work and computer games.
While the merit of using a uniform 1.2 slope effect multiplier for 30-degree is questionable or debatable, it is in fact consistent with at least one simplistic German wartime method for estimating penetration at 0-degree from 30-degree penetration data. To maintain consistency within the game I guess I would tend to run with the games slope multiplier rather than using a more rigorous approach to determining slope effects for the 50mm KwK L42. Moreover, I would simply take the figures for the L42 at 30-degrees and multiply them by 1.2 to obtain the 0-degree values.
50mm KwK L42 firing pzgr-39 @ 0-degrees via ToW slope effects method.
100meters: 53mm x 1.2 = 63.6mm
500meters: 43mm x 1.2 = 51.6mm
1000meters: 32mm x 1.2 = 38.4mm
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I spotted an unrelated an error in the Tiger-1’s listed muzzle velocity for pzgr-39. The game lists Mv as 733m/s. Jentz lists Mv = 773m/s for pzgr-39. The Schusstafeln for KwK-36 lists Mv = 780m/s for pzgr-39. Whether this make any difference to game play or not would be a function of what the actual games files are using and how (if at all) it is using Mv.
Best Regards
Jeff
[ June 09, 2007, 12:26 PM: Message edited by: Jeff Duquette ]
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Hi Oudy:Originally posted by Oudy:Thanks for your insights and data Jeff. The slope effect I came up with by analyzing the data from the long 50mm gun was:
50mm. Kw.K.39 L/60 (APC Pzgr39 ammunition)
(first penetration number is in-game figure)
100m 80/69 1.159
500m 68/59 1.152
1000m 54/47 1.149
1500m 42/37 1.135
2000m 30/?
2500m 23/?
3000m 17/?
I just wasn't sure if the slope effect varied from different caliber guns or not. Should this number be the same throughout the ranges, or should it vary like it does? As you can tell, I haven't the slightest idea of what I'm talking about. I was just trying to make the figures for the short 50mm gun roughly match the in-game figures.
Do you think the rate of fire would be the same for both the short and long 50mm gun?
Only slightly confused,
Oudy
Real slope effects (SE) should vary as a function of t/d -- t/d being simply the ratio of plate thickness (t) to the projectile diameter (d). If we hold projectile diameter constant, slope effect will increase as plate thickness increases. A thicker plate inclined at 30-degrees will have a greater advantage from slope effects than a thinner plate inclined at 30-deg. Sounds pretty obvious in the sense that a thicker plate should resist more cause' it's thicker. But the added advantage of higher t/d oblique impacts is of course above and beyond the simple advantage of a thicker plate vs. a thinner plate.
As to the caliber thing, I wouldn't worry too much about this level of detail given the caliber of guns in the game. You are of course technically correct in that there are scale effects involved with rigid projectile penetration of steel projectiles vs. steel armor. Larger caliber shot and shell will penetrate more efficiently at the same t/d than smaller caliber AP-shot or AP-shell. In other words, a 37mm APC shell tested against a t/d = 1 target will require more energy to perforate the target plate than a battleship's 15" APC shell fired against a t/d = 1 target. But as I say, I wouldn’t worry about the level of error this introduces as it is relatively small given the gun calibers in the game. There are larger sources of error that make this level of slop relatively insignificant.
As to the range thing and variations you are seeing in your calculated t/d values, if you hold plate thickness constant and projectile diameter constant, the slope effect will remain constant as well. What you are seeing in the variation of SE with range is the plate thickness is varying -- both the 0-degree thickness value and the 30-degree thickness value are changing at each range interval of interest. The t/d is also dropping with increasing range. For example take your values at 100meters and 1000meters range:
100m 80/69
1000m 54/47
t/d for the 100meter range target is 80/50 = 1.6
t/d for the 1000meter range target is 54/50 = 1.08
We are holding obliquity constant at 30-degrees. We should therefore expect the thicker plate (the 100meter range target with a t/d=1.6) to have a greater advantage over the attacking projectile than a thinner target. In other words the slope effect for the thicker target should be higher than that of the thinner target (the thinner target being the 1000meter range target with t/d=1.08). Examining your calculations of SE based upon the 50mmL60 we in fact see that your slope effects do make physical sense. Your numbers were:
t/d = 1.6, SE = 1.159
t/d = 1.08, SE = 1.149
1.159 > 1.149
What I would probably use for 30-degree obliquity SE for APC\APCBC would be as follows:
SE = 0.0854Ln(t/d) + 1.2695
SE = Slope Effect for 30-degree Obliquity
t/d = plate thickness divided by plate diameter
Ln: is of course natural log
For example:
t= 50mm
d= 50mm
t/d = 1
SE = 1.2695 (or 1.27 is fine)
These are average slope effects for APC\APCBC. They are not unique to specific foibles of a given projectile, but they are reasonably good for game purposes and should let you convert 30-degree penetration data to 0-degree data. Best results are bounded by t/d = 0.25 and t/d = 1.7. You can extrapolate a bit as long as you don’t stray too far east or west of the above t/d boundary conditions. Another boundary condition is that the function will not yield reasonable results for APBC or AP or subcaliber penetrators.
So yes you should see a variation in SE with range – but not because of the range itself – if you get my meaning. You see the contrast only because plate thickness and t/d will vary with range. This is a function of how penetration data is typically presented in mass consumption reference materials -- ala Jentz, Chamberlain, Hunnicutt, etc. I think it is easier for folks to understand penetration data in this format, or maybe we have just grown accustomed to seeing penetration data in this very watered down format. Real ballistic testing data is invariably presented in terms of limit velocity or limit obliquity and failure criteria. There are many more advantages to discussing plate perforation in terms of limit velocity or limit obliquity, but that is perhaps something more appropriate for another discussion.
I think your approach of using the 50mmL60 data to back out the L42 data is very logical and probably the best and most valid approach to the question. Much better than my initial approach of looking at 57mm M86.
The problem as I see it may be rooted in how the game designers are dealing with slope effects. But I need to plug and chug through some additional examples to make sure the 57mm M86 example isn't simply some weird outlier.
Best regards
Jeff
P.S. I’ll see if I have something laying about on ROF for the L42.
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Thanks a bunch. Got your email. I'll give him try.
Best Regards
Jeff
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Finn:Originally posted by FinnN:Also for each gun there's a minimum and a maximum aiming distance as well as a maximum range, a dispersion at 1000, an aim radius for various distances, a series of 'LinesH' and 'Lines' and a series of penetration values. There are also tables for different types of weapon aiming at different types of target. Obviously all these could have an effect, but which ones are used by the game engine and for what I'm not sure. For example the grouping stuff above - is it for damage? For targeting groups? A modifier for morale effect if one goes off next to you? Projectile dispersion?
Have fun
Finn
What are you using to look at the games data files?
Thnx
Jeff
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Perhaps this was the tactic you should have used in the first place rather than the extremely creative frontal assault.Originally posted by Wildwolf45:</font><blockquote>quote:</font><hr />Originally posted by Jeff Duquette:
</font><blockquote>quote:</font><hr />Originally posted by Wildwolf45:
I ended up having to order another squad in and they managed to catch it on the flank.
Out of curiosity, how many casualties do you personally think is a reasonable number when conducting a screaming stand-up and sprint frontal assault against an AT gun blasting away with HE? Zero, one, two, three, four, six, eight? Or are any one of these casualty rates a statistical possibility?</font>
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Sorry – the above doesn’t help you with making the new tank. Here are 0-degree Obliquity perforation values for 50mm L42 firing APC:
100meters = 73mm of RHA
500meters = 59mm
1000meters = 45mm
1500meters = 34mm
2000meters = 26mm
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Excellent work Slaphappy.Originally posted by SlapHappy:After looking at some of the data for a bit, it seems that there are 3 primary data elements that affect grouping
KDistance - Which seems to be a modifier. It's value is always less than 1.
Grouping Dist - Which seems to be a baseline in meters.
SizeTargetForGrouping - Which seems limited to two types man-sized? or 1.8 and vehicle? or 9. All the small arms are based on the 1.8 value, while shells are based on the 9 value.
Machine Guns are all lumped under one heading at least for these variables. There is no light or heavy differential. However, HMG appears on a separate table which uses an index of 9 for SizeTargetForGrouping along with the tank/gun shells. There is also a pistol, SMG, and Rifle group. Of course, there might be other variables not in this formulae which affect the final value as well.
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Never mind about my last idea. I started looking at the games slope effects model, and I’m not quite sure what to make of it yet. Below are comparisons of actual terminal effects data for the US Army’s 57mm M1 antitank gun firing M86 APCBC. I am comparing the actual testing data for the projectile with the ToWs penetration data. I have assumed that the games penetration data for the M86 represents penetration at 0-degree obliquity.
As you can see from the first graph, the ToW M86 data is a bit skewed from what one normally sees for performance of this projectile.
I pressed on with back-calculation of the ToW slopes effects, but the results are very odd. When determining slope effects for a projectile from proving ground data, one will tend to see some statistical slop, but the general trend for full caliber AP-shot and AP-shell will always be increasing slope effect with increasing t/d. They are directly proportional. In the second graph I show actual slope effects as determined from ballistic testing of the M86 projectile (actual test results shown in red). There is a bit of scatter in the data as one would expect, but the trend is one of increasing slope effect with increasing t/d.
I have also included Lorrin Bird’s average APCBC slope effect – shown by the blue curves. These blue curves are of course generalized slope effects and represent Lorrin's averaging of a large number of APCBC projectiles. Again, the thing of importance to note here is the increase in slope effects as t/d increases.
The ToW slope effects for this projectile are represented in yellow. These were calculated by utilizing the ToW listed data for the 57mm M86. I than utilized the projectiles actual performance at 20-degrees and 30-degrees to back-calculate the games slope effects. For example:
ToW Data: 57mm M86 APCBC penetration @ 0-deg @ 100-meters = 94mm of RHA
Actual 57mm M86 APCBC penetration data @ 20-deg @ 100-meters = 89mm of RHA
Actual 57mm M86 APCBC penetration data @ 30-deg @ 100-meters = 79mm of RHA
t/d = 94/57 ~ 1.65
Slope Effect @ 20-deg = 94/89 ~1.056
Slope Effect @ 30-deg = 94/79 ~1.190
Slope Effect Assuming Simple Cosine Relationship would be a constant at all t/d ratios and would be:
@ 20-deg ~1.064
@ 30-deg ~1.155
The trend in the ToW slope effects for this projectile is of course completely opposite of what one should expect. Moreover, the yellow ToW slope effects curves represent a decreasing trend in slope effect as t/d increases. This is obviously rather contrary to how this type of projectile should be expected to perform.
Best Regards
Jeff Duquette
[ June 07, 2007, 07:38 AM: Message edited by: Jeff Duquette ]
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Oudy:Originally posted by Oudy:I need a little assistance from ballistics experts.
I'm trying to add a Pz.IIIG with a 50mm Kw.K.38 L/42 (short 50mm gun) to the game. The Pz. III with the short 50mm gun is not in the game, but it was a major player in Barbarossa. It is simple to switch guns and alter armor values, but the data for the this gun isn't in the game data files.
I have the penetration data from Jentz, but I need some additional information.
Info needed:
Reload time or Rounds per minute
Maximum firing distance
Muzzle velocity for the 50mm SPgGr 38 (HE) shell
It would also be nice to have additional penetration data (other than Jentz)
Finally, does anyone have the mathematical formula for converting armor penetration values from 30 degrees to 0 degrees?
Thanks in advance for any assistance.
Oudy
Excellent idea. The game does need the earlier PzIII models.
Regarding your slope effects question, it is complicated as slope effects are a function of obliquity, t/d ratio and projectile type. German wartime estimations also included a slope effects factor related to impact velocity.
I have not looked at this two carefully in game terms, but as I understand this from earlier disscussions on the subject, the Anglo-Allied penetration figures represent 0-degree values. What you might initially try looking at is obtaining 30-degree penetration values for Allied guns firing the same form of projectile as your 50mmL42 KwK. I think the early 50mm KwK would be firing mostly APC, so look for Allied guns in this caliber range and same projectile type -- 2pdr, 6pdr, 75mm are possible candidates. Divide the 0-degree values provided in the game by the 30-degree values you have obtained from a little bookshelf research. This will give you an idea of what sort of slope effects multiplier the game designers may be employing.
Moreover, lets say the game data for a specific gun has a penetration value of 50mm at 100-yards at 0-degrees. Pop open one of your tank books (or do a google) to see what the author gives for 30-deg penetration. Most references indicate penetration in terms of 30-degree obliquity. Lets say the reference indicates the gun does 40mm at 100-yards at 30-degrees. Your slope effect is than the game 0-deg penetration value divded by the 30-deg value....50mm/40mm = 1.25. In other the game designers are implying that the projectile type does 1.25 times more penetration at 0-degrees than it does at 30-degrees.
[ June 06, 2007, 01:49 PM: Message edited by: Jeff Duquette ]
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Originally posted by FinnN:
I guess it'll be (penetration at 30 degrees) x (Cosine 30 degrees), so 0.866xP.
Have fun
Finn
Of course penetration should be greater at 0-degrees than 30-degrees -- not less as you have implied with the above. I think what you are trying to say is given penetration at 30-degree obliquity what is penetration at 0-degrees. Assuming a simple cosine function for slope effect the answer is:Penetration @ 30-deg divided by COS(30) = Penetration @ 0-degrees.
But this particular type of AP projectile is not well suited to prediction of penetration via a simple cosine function -- that is it's not well suited for any sort of plate inclination beyond about 8 or 10-degrees from the normal. Moreover, the actual performance vs. a cosine function diverges rapidly beyond about 8 or 10-degrees.
HE rounds r made wrong?
in Theatre of War
Posted