HerrTom
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Posts posted by HerrTom
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Also, a slight correction from my big post with the plots - the first equation set is the THOR equations. I somehow mixed them with the Mott equations which describe the fragmentation pattern (the last two plots).
Damn - and I also meant to say the Recht and Ipson model takes into account the material plug created by the penetrating object. I think it comes largely from first principles and was later verified against data, compared to the purely empirical THOR equations - which are limited by their very definition.
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My phone is not kind to me and I'm a bad checker haha. I meant to say that Erwin is a war GOD!
Though maybe a "war his" is a sort of demigod? The machinations of the mind are endless... or something like that.
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2 hours ago, Erwin said:
Understood. However, in these cases (Missions #1 and #2) the defender would be better off waiting in ambush. Any attacks by the defender given the Russian strength (and vision/spotting capabilities) seems suicidal.
Or, it could just be that I am such brilliant player. Take your choice.
I choose to believe you're a war his the likes of which the world has never seen. Spartacus, Alexander, von Manstein, Rommel and Schwartzkopf all wrapped into one.
I may be misreading this, but is the scenario pack tied into a patch?
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I was under the impression that shells were thinner on the cylindrical section line these 152mm shells. Further looking shows this is not always the case. Thanks!
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Yep, Muzzleflash beat me to it. It seems artillery shells are slightly thinner along the sides so when the blast starts pressurizing the inside, it shatters there first, taking most of the energy sideways. There are also some fragments from the ends, but they are much slower and larger, generally.
It's also worth noting that the spray shown in the histogram is larger than it looks. I'll try to put together a graphic to show it better tonight.
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I've been hard at work reading a lot of papers dating from the 2000s all the way to the 1940s about penetration mechanics and artillery shell fragments. It's been quite exciting. I still have some work I want to do regarding making a probability field and a "lethality plot" of an artillery shell against various armor plates.
So - here are some hopefully interesting plots. Here is the velocity of fragments from a 152mm shell exploding.
This contour plot shows the velocity of fragments as they get further away from the epicenter. As one would expect, heavier fragments are able to travel further, faster - since their weight versus their surface area is larger.
Fragments traveling more than about 60 m/s are generally going to be lethally dangerous. The dangerous speed is faster for smaller fragments and slower for larger fragments.
The following plots use the Mott equations of armor penetration, which are quite old, but still considered somewhat reliable for at least a first guess. They use data from the top graph as an input.
The Mott equations were created from empirical data from shell penetration tests in the 1940s, and as such has some doubt in my mind to the applicability to artillery shell fragment penetration. Nonetheless, it remains a common model.
What's worth noting about the Mott equations is how quickly the penetration velocity falls off.
I also created some plots using the Recht and Ipson model - which is supposedly better for penetration of materials with a similar thickness to the projectile - which is more like what we're looking at here - fragments of ~1 inch thickness penetrating steel plates ~1 inch in thickness.
The Recht and Ipson model takes into account
Note that the penetration on the thinner plate is actually slightly worse using this equation compared to the Mott equation! This model then shows the fragments capable of penetrating significantly thicker armor compared to the old Mott model. According to the Recht and Ipson model, you'll need a 3" or 76mm plate to be relatively safe against 152mm shells.
Finally, I hope to get a probability field using the artillery shell fragmentation presented in one of the papers that has already been posted in this thread using the probability of fragment mass:
As well as the angular dispersion of fragments on the cylindrical section of the shell.
That's all I have for now, but I'd be happy to answer questions and I'll try to analyse the data I already have in a bit more detail later.
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Wow look at those holes in the track covers. That must have been noisy.
3 hours ago, IICptMillerII said:My main point has been that HE artillery is not an optimal tool to use to destroy tanks.
I'm not sure anyone has been arguing against that. I think the main argument is that in the chance that artillery lands nearby tanks and other AFVs, they appear to be less vulnerable in CMBS than they should.
Regarding modeling, I haven't had much time to do it so far, but I hope to free up this weekend. I'm just as interested to see the results - still have to figure out how to present any data in a useful and legible fashion.
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@John Kettler I think the scale on mass may be grains, since ballistics people can't be bothered to use even the imperial units we American measurement pariahs use. That would place the largest fragment 15x larger than you said. Or 60x as much as a .45ACP bullet.
EDIT: Bah, I'm wrong. I even got the conversion way wrong! Interesting question... This requires more research.
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@John Kettler I found the document:
WARHEAD PERFORMANCE CALCULATIONS FOR THREAT HAZARD ASSESSMENT
Document # ADA509688
In particular, from page 5:
When I have the time and motivation, I'm going to plug away at some of the (extensive) data you presented in your previous links and attempt to make a model of fragment penetration according to:
http://www.globalsecurity.org/military/library/report/1997/penetration_equations.pdf
We'll see what we find.
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8 hours ago, John Kettler said:
whereas MOAB, a thermobaric munition
Are you sure about that? I'm pretty sure that the MOAB is just some 18 kips of TNT or tritonal in an aluminum body. The aluminum gives way easily maximizing the blast, instead of a focus on fragmentation like smaller bombs.
I thought you were confusing it with the BLU-82, which I've always heard was a fuel-air explosive, but apparently it's just 12 kips of ammonal. Whodathunk?
By contrast the Aviation Thermobaric Bomb of Increased Power, which all the news is saying is the Russian "equivalent" of the MOAB, is, as its name suggests, a fuel-air explosive.
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11 hours ago, John Kettler said:
TheForwardObserver,
Do you by any chance have any sort of frag size and weight breakdown for when 155 mm HE PD detonates? Haidul talks about a heavy fragment ripping through the side of a BMP and setting it ablaze, which I got me curious. Also, I recall an incident (during the SAE, maybe) in which a large frag from 155 mm HE PD, much to the surprise of the testers, speared right through the turret side (didn't go clean into it, but stuck partially into the interior, causing spall for sure) of what I recall as being an M60, though that may well have been a M46 or M47. Any idea how I can get a copy of the full SAE? Would love to read it.
Regards,
John Kettler
I've looked in vain for the SAE results. My guess is the detailed results may still be classified, though it's curious the artillery article uses images and data from it. Maybe it's a FOIA request away...
I also found a breakdown of fragment weight and velocity by angle somewhere. I'll post it when I find it.
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I for one think it's perfectly reasonable that a C130 would fly over the frontlines in CMBS' world in order to deliver a MOAB. It's not like it's an easy target or anything.
The Russian thermobaric bomb at least has the advantage of (on paper) being delivered by a strategic bomber.
Doctrinally, these are obviously released to the platoon leaders to call on at will, right?
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Remember how the last Emu War went? Imagine now emu, sheep, and kiwis! The horror! The suffering! I can't see why Aussies would ever put themselves through that!
OT: It's interesting to see kitted out Kalashnikovs. It still looks a little wrong to me. Would Spetsnaz have any real role in Combat Mission? I know Cold War plans had them sabotage ammo depots, bridges and other disruptions during the opening shots of the war, but those actions don't seem to fit CM's picture.
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0820
2nd company moves out, alarmed to see Russians straight ahead. I have a feeling that the Russians were just as surprised to see an entire company come over the hill!
The battalion attached tank moves down the road along with the headquarters section, which includes one PRP-4, a BMP-2, and an MTLB. These contain the battalion headquarters, an air observer, HQ support team and another FO.
One of 2/4's tanks receives a Bastion, detonating the ammo rack.
Its comrades return fire, exploding a Ural crossing the bridge.
Meanwhile, the headquarters receives autocannon fire from downrange. It's not clear if the MTLB and PRP are knocked out yet, but I'm marking it as such on the map for now.
While 2/1 moves into cover behind the trees, one of its BMPs receives a penetrating hit, forcing the passengers to bail out.
Artillery begins to slam into the bridge. A number of shells hit it, though most land in the water. A couple of BMP-3s cross over the bridge as the shells land around them (Ahem!)
A T-72B3 shows its ugly face as it drives into Pryvitnoe. This would normally be very dangerous, but the survivors in the town are heavily demoralized and lacking heavy AT assets. The ATGM team has one more left, but I doubt their ability to engage in close combat with this bugger.
One of 2/4's T-64s knocks out the BMP harassing the headquarters group.
Not much has changed. I'm still hoping I can get 3. Platoon, 2. Company into the northern end of Pryvitnoe to discourage Russian probes further north, allowing me freedom to maneouvre around the northwest area shielded by the trees. Perhaps even get an AT asset into the small complex there.
Only time will tell...
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For what it's worth, I think an SSD vs an HDD likely only affects the load times. I doubt CM loads anything dynamically from the disc, or if it does, it's not often.
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Thank you John for the plethora of information. That fragment modelling one might take me a while to parse - a lot of math, even for me!
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33 minutes ago, Artkin said:
Must be those blast doors
Haha! Pure depleted uranium, I hear!
I've continued to search through DTIC, and while I've found a lot of interesting things that I've saved (like a series of books on designing ammunition, including artillery shells) I haven't really found anything particularly useful on artillery fragments' effects on armor beyond the things I've already posted.
If only the USSR/Russian Federation maintained something like DTIC, then we might be able to see some reports on their artillery tests...
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2 hours ago, shift8 said:
Right but this doesn't mean much. If you read the hard data later in the document, the number of perforations per shell per square foot are measured in the .01 and similar. The chances of a penetration is so low as to be more or less assured for practical purposes.
All things being equal:
A BMP presenting its side to an artillery shell at 30 meters presents approximately 0.4 steradians. Okay, I'll give you that - it's not a huge angular size. But even at that, you have 0.6314 (from the data there) perforations per shell on this vehicle - those odds don't seem so insignificant under an artillery barrage.
Now P(H) isn't the same as P(K), which I can't really provide data on - but I think it's safe to say that a perforation has a chance to damage interior components.
If we take this shell and move it closer and closer to the vehicle, the solid angle will approach 2pi steradians as it lands directly next to the vehicle - 15x larger! Even using the data from the 90 foot blasts, you can see that the number of fragment impacts are going to dramatically increase. Unfortunately, they don't seem to have data of steel plates at anywhere closer than 90 feet, so I can't give hard-er numbers to give an idea of the penetrations you'll see per shell. But we can reason our way to an educated guess:
Fragmentation hitting the target shouldn't change if the solid angle doesn't change (ignoring them hitting things or gravity and things like that). So we can guess that the BMP will receive about 15x more hits as it gets closer to the vehicle.
We can also get a rough guess as to the increase of penetration power by looking at the 1 1/4" aluminum plate they used in the phase I testing. I'm going to do some math with this and see what I find.
Using an exponential fit to the data plus a scaling factor to match the aluminum plate with the steel plate performance at 90 feet (oddly enough it seems 1.25" of aluminum is roughly equivalent to 1/2" of steel. Cool!
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Page 13 of the Swedish-sourced study says " At 90 foot standoff distance, 100% protection cannot be obtained against... fragments from the 155-mm, HE, M107 projectile using thicknesses of rolled homogenous steel armor of both specification and modified hardness up to and including 1/2 inch."
Here's (the only such, oddly enough) image of the BMP-1's armor thickness (Plus a Marder for fun and profit!)
The data in that study would mean that the rear and top armor are not thick enough to protect it from airbursts and groundbursts within 90 feet, or about 30 meters. Now, not every shell would kill or even penetrate the vehicle - but there's a chance.
At any rate, I'm more inclined to believe the data presented in the real-world tests in the Soviet Artillery Effectiveness study compared to the almost 30-year prior study. Both provide data, but a different type.
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Honestly I would kill just to have it run smoothly. I don't buy the whole "calculations in the game are too complicated" argument, especially seeing how much a difference is made by changing quality levels. I can hit a smooth 15 FPS by going to balanced in Galloping Horse Downfall, compared to 5 on best and 20 on minimum. Looking around the map drastically changes that.
Funnily enough, reshade for the most part doesn't affect framerate significantly.
Maybe sbobovyc is right, and legacy OpenGL is killing us.
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4 minutes ago, DreDay said:
No doubt. One question that I have though (outside Saudi issues) is the performance of turbine engines in high altitude. I remember hearing that their performance gets significantly downgraded when you get high above the sea level. Is there any truth to that, or is that just an old wife's tale?
Ostensibly, this makes sense. Air density lowers with altitude and gas turbines are more sensitive to the amount of air entering them. But, even in Colorado (for example), the air is on average only 90% as dense as sea level, which I imagine impacts engine performance even less than 10%.
An ICE will also run a little worse too, so I'm not sure the difference between the two would be too significant though.
I'm no expert though, my experience is mostly with other types of engines.
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Ceramics won't be happy, they'll fracture and pulverise under shock. I am not sure that that will significantly affect its ability to resist penetration though. CMCs would fare better than pure ceramics, but not much.
DU and tungsten have a similar problem in their lack of ductility, though they are significantly tougher.
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The tests from the article were a 4-year-long study starting in 1988.
As for the 1960 study, which you seem to have confused, steel is steel. They ran tests on plates, not vehicles. Yes, modern vehicles have more complex armor in certain areas, but others are still just steel.
I'm trying to find more on NATO standards for testing armor as well as looking to see what the USSR let leak. Hopefully I can find something juicy.
Edit: You seem to know something we don't. By all means show us a source to back up what you say. I want to figure out how accurate the game is. My gut says something is wrong, but that doesn't mean anything in this kind of argument.
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Thanks Ian. I hadn't really noticed that. Good to know!
c3k, the Ft Sill publication should be the second link in my post. I would have linked to the pdf oh the army website but it's currently having routing issues I think. On the rest, I agree, a good model of this problem needs to be stochastic in some sense to capture the immense variability.
I seem to remember someone saying that explosives on this game were scaled down, at least for infantry, due to engine limitations with spacing. This presents a bit of a conundrum: Do we scale it's effect on vehicles to the same level? Do we present realistic effects for vehicles, but then be inconsistent in effect between target types?
Maybe the new engine's infantry behavior has mitigated the original problem?
Unofficial Screenshots & Videos Thread
in Combat Mission Black Sea
Posted · Edited by HerrTom
It's awful! I've lost 3 or 4 T-64s to brave BMP-3s firing ATGMs, and one of them was to a 30mm cannon on the front arc. Needless to say, that surprised me. At any rate, I can attest that they use ATGMs at ranges around 1 km.
Kaboom. They charge fearlessly, firing ATGMs while driving at high speed. It's like they're piloted by a crew of Arnold Schwarzeneggers and Sylvester Stallones.
Edit: I wish we had more modding control over the explosion graphic and how it scaled - sometimes it gets a little ridiculous (see above!)