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Comparing HMG Damage, and issues with .50 cals


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edit 2: Yep, I'm not smart enough to calculate this. There are certain constants and equations you have to use based of the relation between the thickness and round diameter and I can't seem to work out which one it is. The example equation doesn't seem to use the correct one so must be reading something wrong. 

 

edit: I'm not 100% sure these calculations are right, I've made what I think are potential corrections below. Certain constants need to be used based off the relation between the size of the round and thickness of the material. 

 

This is actually pretty interesting stuff. I didn't think I'd be as into calculating this as I was. It's definitely a workable model to use.

 

Things that have a massive impact are thickness and material type. We are restricted in terms of 3 types of aluminium so we would need to understand which one is closest. From what I can find, 2024 is used as skin and 7075 would be used for strengthening structures. The difference between 2024 T3 and 2024 T81 is still pretty significant so we would need to understand which one was more likely to be used. 

 

I've so far calculated NILMD, which is the maximum damage under normal impact (perpendicular). 

 

2024 T3:  1.9928125 inches      after recalculating:  0.7954067528 inches

2024 T81:  3.7295125 inches    after recalculating:  1.598178394 incheas

 

(I've got a spreadsheet that can calculate these now which I will share once I've worked out how to do the angled ones)

 

I've also calculated the HVLD, which the high velocity damage (this is the same of both types of 2024)

 

HVLD:  0.75972 inches

 

Now if I'm reading the below chart correctly, V1 = 100, V2 = 500, V3 = 1500

 

1737584498_Screenshot2021-01-30at18_09_59.thumb.png.e9d8e8143beaf796f98ee270fe8d1b3b.png

HVL

We then apply this to the graph provided. 

 

427761487_Screenshot2021-01-30at18_07_54.thumb.png.80bcfa2bb686bdb08a3efbcc68baf840.png

 

 

So at normal ranges where velocity is definitely going to be >1500 ft/s, at a perfect perpendicular angle a .50 round is going to leave a maximum size hole of 0.75972 inches in diameter. 

 

What we now need to understand is, what is the velocity loss after penetration? The maximum damage is achieved at 500 ft/s and roughly looking at the graph, 1000 ft/s would give you a maximum approximately halfway between HVLD & NIMLD. 

 

Of course the NIMLD isn't a perfect 4 inch round hole in these examples, it is likely a crack similar to this:

 

1168711147_Screenshot2021-01-30at18_37_58.thumb.png.770b36e8bfb9deeda98a7cdcba2f7c5b.png

 

So the maximum damage at a perfectly perpendicular angel is pretty insignificant, but that's not a huge surprise as the surface is only 0.090 inches thick. 

 

The big question - how thick is the skin on a ww2 aircrafts wings?

 

 

 

 

Edited by Cass
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Differs greatly. Japanese aircraft for instance typically use a lot thinner skin than US aircraft, German/British ones are somewhere in between. And then there's the size of the aircraft, the type, particulars of the part and so on.

 

Some info I found quickly because I still remembered where i read it: The Bf110 wing skin ranges from 0.8mm to 2.1mm in thickness.

 

For the Fw190 it appears to be a little bit less, couldn't find the exact range, but 1mm is not wrong - there are bits that are thicker and bits that are thinner, that I know.

Edited by JtD
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@unreasonable we can play the conspiracy and suppression of information game, or we can be honest. 

When we presented our data, we did not state what our outright goal was, or tell the devs what do to. We will not pretend to have knowledge of how the game works that's comparable to the devs. All we did was compare similar weapons in a live environment. 

We found that MG131's and UB's performed better than the M2's in the structural damage, and far far better than the M2's in the Aero metric. We did not explicitly state that the .50's aero or structural penalty be improved.

We said that M2 .50's seem weak, and that 131's and UB's seem strong. 

 

For the life of me I cannot find any documentation proving that the UB and 131 guns should be 25% more effective at structural damage than the M2's. I also can't find any to support that 131's and UB's are 2000% more effective at tearing up an aircraft wing from a rear aspect shot than the .50's. 
 

I can find information (thanks to the wonderful participants of this thread) that from the aspect that we shot at the target with, the M2's should be creating large gashes in the wing surface, and not creating perfect .5 inch holes in the wing. I can find information that the Germans eventually switched to an API only belt for the MG131's. It doesn't seem logical to me that you'd stop using a round that can cause a 50kph speed penalty on a bandit for an incendiary component. 

 

I can also find information that the tidying up of an airframe and sealing of the gunports can yield a 20mph improvement in an aircrafts maximum speed. 

Through in game testing we found that 70+ M2's will not create a speed penalty greater than 3mph. 15% of the above figure. In game testing also shows that the MG131 and UB guns will cause a 30mph speed penalty with 2 hits. 150% of the above figure. 

 

That's all I'm saying. 

 

I'm just looking to compile and present data to the developers so they can determine if they should do a second pass on the DM. I will not pretend that I have the know-how and resources to calculate the hypothetical real world outcomes of these tests. I'm also not a fan of letting other folks pretend that they somehow do have these resources. I'm a huge fan of people presenting legitimate documentation on all ammunition types used in the test, as well as their performance under various conditions. 

 

Quick aside, @Mitthrawnuruodo I am aware that the physiology changes were made due to a player bringing attention to some documentation that presented a different model, and was performed under different conditions. I'm hoping that we can play a similar role. I don't recall the individual telling or encouraging others to tell the developer exactly how to make their game. I don't plan to do that either.

Edited by QB.Shallot
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Just now, QB.Shallot said:

@unreasonable we can play the conspiracy and suppression of information game, or we can be honest. 

 

That would be good. So here are some facts:

 

Your definition of the damage levels is incorrect and potentially misleading, as my screenshots show, since you do not state or show pictures in the OP of what you meant by "level 2". Something that is still uncorrected. Adjusting for that, I have not disputed your numbers.

 

Nor have I said that the ratio of damage between the rounds in the game, or the absolute values of either, is correct. Quite the opposite: I have repeatedly said, in this and previous threads on this subject, that it looks intuitively odd, and needs some justification if it is to be believed, and may need significant revision. Also that API should be in the game with other incendiaries, explicitly modelled.

 

Most of my posts have been directed to various other posts that contain misunderstandings or factual mistakes.

 

I have explained how the use of percentages in ratios is potentially misleading, especially in red bold emphasis, as shown by the case of the poster who misunderstood this figure as a measure of total effectiveness, with no understanding of gearing effects.

 

I have said that it is untrue that high velocity shots at an aircraft wing cannot ricochet, also pointed out that the definition of damage size in the ASGAR report is not necessarily the size of the holes but a larger definition. Also, slightly OT, that mixed belts were not the optimum. 

 

I have said I would like to know if we have more information of the effect of various holes on aircraft wings, since this seems to be the largest empirical gap in our understanding. So I provided two links to scientific papers doing just that.

 

None of this is having an argument with you, unless you choose to make it one.  

 

A large number of posters here and in other threads, identifying as "allied players", wish to see aerodynamic damage from .50 cals substantially increased, one reason often given, that they find it frustrating that a burst of .50 cal AP does not cripple a target. I am perfectly happy to go with what the data shows, including this result if it is justified.

 

The side I am on, is the side that wants the DM to be, as far as possible, based on facts and well grounded theory, not based on the subjective preferences of a MP faction or calls for balance.  I am assuming that we are on the same side: in which case you should be as concerned as I am, when people misunderstand or misrepresent data, and less defensive when other people wish to continue the topic by constructing their own checks for reasonableness of the game's results. 

 

As the OP you can always ask people to start a new thread if you think that the discussion has strayed too far.

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2 hours ago, unreasonable said:

As the OP you can always ask people to start a new thread if you think that the discussion has strayed too far.

 

I feel like we have both been trying to drop hints so you would stop derailing this discussion for the last three pages of this thread. 

 

Side note... I went back and edited this post to address your concerns regarding our definition of "level two" aerodynamic damage: 

 

Edited by QB.Creep
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12 hours ago, Cass said:

There are certain constants and equations you have to use based of the relation between the thickness and round diameter and I can't seem to work out which one it is

 

Where?

 

Given that the limiting velocities and the HLVD are easily calculated, wouldn't it be easier to check what speeds are relevant in the first place? According to the model you can simply use projectile speed times cosinus impact angle to determine v*, and as long as v* is bigger than v3, use HVLD. Which as far as I can tell you've calculated properly (for a 0.09" plate).

 

At 400 yards, you should be at somewhere around 2400fps projectile velocity, as 1500fps is the limiting v3, anything less than 50° off the perpendicular will produce HVLD, in the range of about 0.6-0.8 inches. Also, for as long as you produce HVLD, the damage done is small and the energy absorbed is, too, so you can assume without any large error that the projectile will continue uneffected.

 

Obviously, the part we need to be interested in when firing at a wing from the rear is beyond 50° obliquity.

Going with your 0.09"/2024 aluminum skin. Taking T81, because it's going to give a bigger hole. We use C1, because t/d=0.09/0.5=0.18>0.15 (and < 0.85), so

C1 = 9.8

a1 = -31.7

b1 = 86.539

y1 = -83.258

d1 = 31.835

e1 = -3.178

This gives me NIMLD = 1.6", same figure you've gotten to after recalculation. Why did you cross it out?

Edited by JtD
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On 1/29/2021 at 4:28 PM, sniperton said:

What we can plainly claim (and I guess most of us are in agreement in this respect):

1. Allied .50cals are misrepresented in game with inadequate ammunition. [fact]

2. These misrepresented .50cals do significantly less (aero) damage than other board guns with similar caliber, but different ammo. [demonstrated multiple times]

 

So I think there's no need for "further in game testing" on our side. It is not our task "to quantify the bug", it's the duty of the devs to remedy an obvious inadequacy and imbalance more or less frustrating a bunch of players. Human patience is a merit, but a limited one.

 

It's telling tons of stories about these forums and it's users that this absolutely level headed post went completely unnoticed, almost ignored, and people - especially our "nay" saying friends - keep bitching about the tiniest aspects of the issue they can find and think they could work up upon, most likely to derail the thread until it gets locked.

 

The OP and this reply of @sniperton is all there is to say about the issue, seriously.

Any attempt to justify the current reprensentation of the cal .50s says more about the poster than he's trying to tell about the guns.

 

:drinks:

Mike

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@JtD

I think that parts right.

 

I couldn't work out which equation to use. There are 3 different equations for NIMLD.

 

Also in basic form you appear to have to raise certain numbers to the power of 3 or 4 and then in the calculation form that isn't the case.

 

Not sure I'm understanding it correctly.

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The calculation form still has the powers the basic form has, it is just more computer friendly by braking them down into multiplications. Got me, too, for a moment. But this is a 1981 paper, they used buildings instead of smartphones to get some decent computing power.

 

a*x³ + b*x² + c*x + d = d + x(c + x(b + x(a))) - so don't let it confuse you.

 

From what I gather, the 2024-T3 aluminum would be the one most typical for the era, as it or similar alloys were used on most (US) aircraft of the time. The other two alloys are of later date. So the good news would be, that we have a valid upper limit calculation for 0.50 AP on 2024 T3 top right pdf-page 77. It covers 0-3200fps speed range (plotting the maximum obtained within that range), so we can be sure this is indeed the maximum for practical purposes, and it also includes 0-40-70 angles, giving us a good range. So I've decided to stop calculating this and just go with that chart, but if you want to continue, I think you can use it to validate your findings.

 

The interesting thing about that chart is that it remains flat at t/d lower than 0.1 inches or 2.54mm, which, as I posted above, pretty much covers the thicknesses of wing skin typically used on German aircraft. So the upper limit of damage would be somewhere around 1-2" for angles between 0°-70° impact, with all projectile speeds reasonably expectable. Aircraft skin is just so frigging thin. As also posted above, the aerodynamic consequences of such simple hits, even when numerous, are pretty small.

 

There are at least two ways out of this, because at least two important factors are not being included in the above considerations:

In order to do more damage at these angles, you can hit structural elements, but by this I do not only mean spars, but also ribs, panel edges, rivets and so on. This will result in larger damages, including shot off bits of significant size.

Or you need really low angles of impact, at which the penetration (or not) of the first layer does have a significant impact on the ballistics of the projectile, which will not only increase damage on the first layer, but, penetration provided, anything behind it as well.

 

For both cases, the damage equations given, as interesting as they are, are not applicable. This is why I've moved on and find the

 

https://apps.dtic.mil/dtic/tr/fulltext/u2/a030268.pdf

 

also linked by Yak Panther more interesting. Sure, it is discussing spheres and it doesn't go to really high obliquities, but then some mechanics will be applicable to an AP round that is, at low angles of impact, hitting with the rounded flange instead of the pointed tip.

Edited by JtD
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Good points @JtD
 

Agree they don't appear to be relevant. New question: Is it solely the >70 degree shots that are causing pieces to fly off? Unfortunately means we're unlikely to get a similar model due to the randomness associated with hits like that.

 

Interestingly though, deflections internally, unless pieces coming off the structures hit and break through the aircraft skin, are still only able to create hole 2 inches big even at optimum velocity. It's not unlikely that deflections will be <70 degrees.

 

Would the skin thickness be uniform across entire aircraft, or could you expect for instance ailerons, leading edges and cowlings to be thicker?

 

I've found a plan of the panel thickness for the P39s fuselage but it was very thick due to the forces from the drive shaft (0.3-0.4").

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On 1/20/2021 at 7:02 AM, QB.Rails said:

You're telling me at 530 kph he's going so fast that the prop is having no yaw effect on his plane? I don't buy it.

 

The prop blast effect will depend on power and speed. Aircrafts are generally stable at cruise speed and cruise power. Same goes for warbirds. 

With speed, the fuselage participate to yaw stability. 

 

 

On 1/21/2021 at 4:43 PM, QB.Creep said:

I thought you were a stunt pilot?

 

Doesn't make me an aerodynamical engineer. 

 

 

The times I lost my vertical stab in the game, here what happened: 

- My plane was less but still stable on yaw axis as soon as I kept my speed up and fly smoothly. 

- When slowing down (to try to land for example), my plane was progressivly loosing its yaw stability and went into a spin even by flying or adjusting power carefully.

 

It's "aerodynamicaly logic". 

Edited by JG300_Faucon
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I found this as an example for skin thickness distribution on a wing. This is from a general aircraft design book of the late 1930ies. Basically the bending forces as well as the aerodynamic (pressure) forces are mostly taken by the ribs and spars, and you're supposed to reduce distance between them if loads get to high. You don't necessarily make skin thicker. So essentially, the skin doesn't have to take a lot of forces, with the exception of torsional moments on stressed skin designs, but this still allows it to be reasonably thin.

As said above, US aircraft often used somewhat thicker skin than contemporary designs of other nations. This makes them slightly heavier (no problem if you've got big engines), cheaper to produce and more tolerant against front line abuse.

 

 

image.png.d0773812a515d0c634ab8dbc3922e278.png

 

 

I think that pieces can fly off from hits at any angles of impact. You just have to hit the proper spots. Of course, high obliquity increases chances for that.

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One of the things that is a bit unclear in the DM is where the difference between skin and structural elements starts, or what exactly the skin graphics indicate.  It is clear that anything with a distinct 3D hit box (eg wing fuel tanks?) or virtual hit box (eg spars), counts as a separate internal structure.  But I seem to recall a post about the new DM, stating that the amount of stuff in the wing (and presumably other places) was now measured explicitly so that the developers did not have to make so many judgement calls. 

 

I have not done a large sample, but the P-51's wings seem to take a comparatively high number of shots to get the damage graphics. This may reflect a greater number or size of ribs and stringers than in other types as well as thicker skin? Firing at very close range, it is hard to see a slightly thicker skin making much difference to the size of the holes.

 

 

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That would seem correct. Only evidence I've found is a 2005 post on ww2aircraft.net but it states the P47 and P51 had ~.0.04 with most other aircraft a bit below that. Not exactly a gleaming source but it aligns with others.

 

According to 2-42 that you referenced, even 1.5mm (0.06") is still well below the threshold before you see an increase in maximum damage.

 

We're back to conjecture and guesstimation then it seems!

 

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The loose of vertical stab & rudder has been corrected in 190- A8 & D9, so as soon as they loose that part inflight they suddently flip-flop and go down in a flat spin with no possibility of recovery, totaly aerodynamically logic when you loose the one & only part of the fusselage that keeps the engine torque force balanced. 

 

26 minutes ago, JG300_Faucon said:

The prop blast effect will depend on power and speed. Aircrafts are generally stable at cruise speed and cruise power. Same goes for warbirds. 

With speed, the fuselage participate at yaw stability. 

 

You're talking about ideal situations, but when you loose a vertical stab is cause you've been shot and/ or due the high G-forces (remember you're fighting not cruising) and high preassures and parasite drag applied in the damaged parts finished in a ripped off the stab and the rudder, only because you're not in an ideal situation like cruising. 

 

That is the aerodynamics logical at least in planet Earth but then we can disscus if it matches same way in planet PC. 

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On 1/8/2021 at 3:18 PM, Jayhawk said:

So to keep the discussion going with a larger audience. I don't believe that there is an issue with .50's.

A studying of WWII aircraft metal composition found that BF109's had between .5mm and 3mm skin thickness and FW190's had 1.4mm skin thinkness (Source)

If you look at a US Army Study on aircraft survivability from 1971 (Here), you will see on Page 79 that a .50 hitting aircraft aluminum will make a clean hole the size of the round though the aluminum without petaling or crack propagation.The .50 has so much energy it is just blasting though the aluminum not causing any damage.

And if it was just a hollow skin they were shooting at that would all make sense. But what you're failing to take into account is the structure, fuel tanks, engine, and all the other objects inside of the skin. 

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The skin you're talking about is this one, in this case for P-51 

 

499052123_Capturadepantalla(4).thumb.png.daff84abfeda770c83f922228f9331bf.png 

 

But as you've said this skin is (not 100% sure) barely connected with the damage hit/boxes or the hit boxes are empty of A/C internal systems to be damaged, related with some 109 models. In P-51 works fairly well due german bullets are more focused in generate heavy damages in the A/C external skin also critical damages in A/C's with a few rounds. So as soon as your A/C is impacted by them your P-51 will suffer instant asynmetrical drag and an important loss of speed.... well basically the damage what is supoused  for those kind of shells.

 

But with the 0.50 cal only AP rounds..... it's a turbulent love/hate  story to be explained and, of course, to be improved. I can only say after several related opened / closed posts for several months is that the DM works pretty fine over external skins, also 0.50 AP rounds physically impact and go thru (pretty close to their properties IRL when they impact some thin soft materials like the aluminum alloys used in external skins) without inflicting any damage cause at internal level the DM seems to be in panties. This could be a great example when people want to increase the complexity of systems (no problem on that), but they precipitate in their implementation (all problems are going to come like dominoes). 

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At the risk of derailing this just a little bit, I have a question: I've been reading this thread and finding the information here in rather interesting, though I must confess I don't fully understand some of the mathematics. However, it has occurred to me that while there is a great deal of demand for data on why the AP modeling is broken or wrong or what have you, there has never, to my knowledge, been any such requirement of so weighty a proof that the HE modeling is correct as it stands now. So, while we have people here that seem to have a fairly solid grasp on what is, or what should be, going on in this regard, does anyone have any solid information on exactly how HE rounds should behave? I mean in depth, beyond the simple 'they go boom and hurt skin.' I can't help but see how it would be useful as a point of comparison.

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3 hours ago, -SF-Disarray said:

At the risk of derailing this just a little bit, I have a question: I've been reading this thread and finding the information here in rather interesting, though I must confess I don't fully understand some of the mathematics. However, it has occurred to me that while there is a great deal of demand for data on why the AP modeling is broken or wrong or what have you, there has never, to my knowledge, been any such requirement of so weighty a proof that the HE modeling is correct as it stands now. So, while we have people here that seem to have a fairly solid grasp on what is, or what should be, going on in this regard, does anyone have any solid information on exactly how HE rounds should behave? I mean in depth, beyond the simple 'they go boom and hurt skin.' I can't help but see how it would be useful as a point of comparison.

It is interesting that quite a few of the people that don't want to see any AP changes are constantly asking for detailed scientific proof that they should do more while for HE rounds I haven't seen a single comment asking for detailed scientific proof that they are/were correct to begin with.  They seem to have to have been accepted on their face with little if any detailed "scientific evidence" being demanded in the forums.    You don't see dozens of threads with hundreds of posts saying the 20mm HE is too weak or too strong, etc...  It's OK to demand evidence for making a case about something, but to simply demand detailed scientific proof simply because you want to delay or derail changes you simply don't want any seems like a double standard to me.  My guess is that a detailed "scientific" study of the HE effects and damage would reveal serious problems.   Let's be realistic, we don't even know if ANY of the weapons in game are "scientifically" accurate in their damage.   The closet are probably the bombs and even they have known issues.

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3 minutes ago, BCI-Nazgul said:

The closet are probably the bombs and even they have known issues.

Bombs are extremely broken. With default durability values, a 1000 pound bomb cannot destroy a dugout from 10 feet away.

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21 minutes ago, QB.Creep said:

Bombs are extremely broken. With default durability values, a 1000 pound bomb cannot destroy a dugout from 10 feet away.

I thought the target durability could be set by the map maker??   I don't do maps so I'm not sure.   What I was thinking about mostly was the blast wave propagation and lack of distinction between various target types.

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9 minutes ago, BCI-Nazgul said:

I thought the target durability could be set by the map maker??   I don't do maps so I'm not sure.   What I was thinking about mostly was the blast wave propagation and lack of distinction between various target types.

You are correct, and that's why I said default. So the map makers have to reduce the durability of ground targets so bombs can kill them... and by doing so, cannon rounds can destroy them.

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@-SF-Disarray

 @BCI-Nazgul

Thats one of the points I was going for. There is no precedent for low yield HE HMGs to be so much more effective than M2 Browning's. Not only that, but their effectiveness as is, seems to be unreasonably high.

 

The point aero damage between 20mm HE and 13mm HE is pretty much identical. The main differentiating factor is the high amount of splash damage on 20mm rounds, which will do fuselage damage if you hit the mid wing of a 109. I'm just asking for the devs to do a second pass on how damage is calculated, because I feel that there might be some outliers in how rounds interact with aircraft. Some being constantly modeled in their best case scenario, and some perpetually stuck in their worst case scenario. 

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17 minutes ago, QB.Shallot said:

@-SF-Disarray

 @BCI-Nazgul

Thats one of the points I was going for. There is no precedent for low yield HE HMGs to be so much more effective than M2 Browning's. Not only that, but their effectiveness as is, seems to be unreasonably high.

 

The point aero damage between 20mm HE and 13mm HE is pretty much identical. The main differentiating factor is the high amount of splash damage on 20mm rounds, which will do fuselage damage if you hit the mid wing of a 109. I'm just asking for the devs to do a second pass on how damage is calculated, because I feel that there might be some outliers in how rounds interact with aircraft. Some being constantly modeled in their best case scenario, and some perpetually stuck in their worst case scenario. 

 

I think 13mm HE is WAY too powerful and 20mm HE is too powerful as well, but not as much as 13mm.  Unreasonable would now ask me to "prove" 20mm is too powerful, but I would ask where is the evidence that's it's correct as it is?  Just because the devs say it is?  That seems to be the starting point for all these damage threads.

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image.thumb.jpeg.20bd93d9646793c4b58b7b7ff8e00e1f.jpeg

image.thumb.jpeg.3a82f64f04e85a73016544aacbd4e78e.jpeg

These pictures depict a Mávag Héja II, which was a licence-built and improved version of the Reggiane 2000, which, in turn, was an improved version of the Sikorsky P-35. Alloy and manufacturing technology was American all the way.

This airplane, V.539, piloted by sgt. Ferenc Kass, was lightly damaged in a fight with P-38s on the 13 April 1944 over Hungary.

The damage to the right horizontal stabilizer might be the result of a Hispano (20mm) hit. The rest are from .50cals hits. Left wing, left engine cowling, left horizontal stabilizer, right wing root.

Note how the bullet entering from behind chipped off the surface of the left elevator and how it made the skin bent upon impact.

Note the entry hole on the right wing root and the exit hole a bit further.

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Just now, BCI-Nazgul said:

 

I think 13mm HE is WAY too powerful and 20mm HE is too powerful as well, but not as much as 13mm.  Unreasonable would now ask me to "prove" 20mm is too powerful, but I would ask where is the evidence that's it's correct as it is?  Just because the devs say it is?  That seems to be the starting point for all these damage threads.

 

I take the starting point to be the same as in the case of the FM, where the developers' rules are clear. If you think the model is wrong it is up to you to provide the evidence, in the form of track, tests or whatever (in SP) plus a reference document.  The starting point is not about what is correct: it is about what is needed to get change.

 

Look, and you will find a thread on the damage done by 20mm, using the US ballistics report as a reference, concluding that the 20mm HE was about twice as effective in causing one shot kills compared to the reference  tests. That was a previous DM version, and did not look at cumulative aerodynamic damage, but it came as close as I think is possible to "proving" that at least one HE shell was way too powerful in certain respects.

 

Unfortunately, changes to the way the AI gunners work make it immensely more time consuming to replicate that test, so I have been unable to see if the most recent version is closer to the reference. With a player controlled AA gun on the way, testing may be easier.

 

I have said enough times that I suspect both 13mm and 20mm are too powerful currently. Unfortunately, demonstrating that aerodynamic damage is incorrect is much harder that determining one shot kill probabilities since:

 

1) We are short of outside references explicitly measuring speed loss in this kind of case, so we have to rely on theoretical studies, analogy from gun ports etc, and anecdotes.

2) AP and HE rounds are significantly different in mechanism and types of damage.

3) The game gives only three generic damage levels, which have to represent the whole range of damage from a few bullet holes through to extensive but survivable flak or mineshell damage, on all aircraft from small fighters to the largest bombers.

 

If I was tweaking the .50 cal DM, the .50 cal AP would stay as it is, there would be an API shell doing perhaps ~50-100% additional surface damage, plus higher % chance of igniting fuel, and the 13/20mm HE would have surface damage much more limited in area and degree. That would be more plausible to me: of course I cannot "prove" that is right. 

 

As for this constant mention of "derailment" that we see in this and other threads. I find it interesting that posts that are wrong in fact, are not criticised for "derailment", while posts pointing out those errors are so condemned.  So it is clear what "the rails" actually are: a fixed route to one desired destination, not an open discussion on the topic.  Much easier to claim a consensus in "the community" if dissenting voices are absent. 

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I've been thinking in all this mess..... could it be possible that 50's as AP  works pretty near to it main properties? My answer is:  it could be plausible. Could it be possible that the actual DM works pretty fine? It could be plausible. Could it be possible that the actual DM gives more importance to the A/C's surface damages than a the damage in rather simplificated internal systems (also inexistent ones)? Very plausible.

 

My nose is pointing in third case for 2 reasons:

1- german 13mm. HE, also 20mm. HE mainly work that way, massive damage in skin and problems related with flying surfaces.  

2- Russian 12.7 mm. HE mainly works similar to german 13 mm. HE.

 

But AP 0.50 got the main property of penetrating in Hard & thick materials using its special core of tungsten and its higher muzzle velocity. So AP rounds impacts and inflicts damage in systems and skin represented, but if after impacting the skin there is no other internal system represented in game to damage then the bullet does nothing. This matches with the online reports some dudes had contributed: a lot of bullets shot and a huge lack of damage in opponent in the server statics.  Opponent keeping flying with enough energy and lack of damages to stay in combat or just run away, also 109 turning the odds with desperate bursts and dissabling allies A/C when everything was lost for them.  I might not accept those problems due net lags or high pings: it never happened to anybody otherwise this forum would be full of complains from german pilots reporting that.

 

For those reasons I'm starting to change my COMPLAIN (still being a complain) from 0.50 AP rounds to a problem, glitch, issue, lack of programing, whatever you want to call it in the DAMAGE MODE. But  the bad new of all of this is the long term time we should have to wait to see a more complex damage system developed and the API rounds.

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1 hour ago, QB.Shallot said:

@sniperton Are you able to find any more examples of aircraft shot at by M2 .50's? I've done some preliminary looking, but it doesn't seem to yield many results. Then again, I might be looking in the wrong places. 

You'd think that would be easy, but it in all the years I've been reading about WW II I've seen far more pictures showing FLAK damage to Allied planes.   Pictures showing air to air damage against Allied planes are harder to find and pictures of Axis planes damaged by air to air fire are even harder to find.

 

Surely, the Germans, English, Japanese did some official studies about fighter weapon effectiveness.  Someone needs to find them.  I refuse to believe they armed planes based on "guess work" and word of mouth accounts.

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@BCI-Nazgul I've noticed the same. It makes it really hard to compare damage done with hard real world evidence. Gun cam footage will always be ridiculed for being selected because it makes the weapons look effective. The next best thing would be photographic evidence of an aircrafts state after taking nonlethal fire. 

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4 minutes ago, QB.Shallot said:

@BCI-Nazgul I've noticed the same. It makes it really hard to compare damage done with hard real world evidence. Gun cam footage will always be ridiculed for being selected because it makes the weapons look effective. The next best thing would be photographic evidence of an aircrafts state after taking nonlethal fire. 

The best document I've seen so far was the US study that Unreasonable found, but it is very limited in both targets and weapons.

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@BCI-Nazgul the documentation is useful. But as was shown even in just one example, seeing these weapons in use in the wild provides interesting perspectives on the damage they can produce. Even peeling away edges of panels that they strike for example. I’ll try to do some more hunting tomorrow. I have a feeling I’ll at least be able to find pictures of the UB guns in action.

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2 hours ago, BCI-Nazgul said:

You'd think that would be easy, but it in all the years I've been reading about WW II I've seen far more pictures showing FLAK damage to Allied planes.   Pictures showing air to air damage against Allied planes are harder to find and pictures of Axis planes damaged by air to air fire are even harder to find.

 

Yes, it's amazing. I also kind of expected to have pictures of 0.50 jump at me when just going through the regular literature. But somehow, it's nearly always freshly polished machines on a nice summer days...

 

Might be worth going through this topic:

 

https://ww2aircraft.net/forum/threads/battle-damaged-aircraft-of-ww2.15431/

 

Lots of big caliber damage, but certainly also 20mm HE stuff in there, and since you've been wondering about HE damage as well, might be intersting.

WRT 13mm HE - this is not really something you do for structural damage, you do this to rip internal components apart - in particular fuel tanks. Essentially and simplified, 13mm HE is the equivalent of 0.50 API.

 

Regarding the Heja - do I see this right that one prop blade has been chipped (first pic)? Probably from the hit that went through the cowling, if so.

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2 hours ago, BCI-Nazgul said:

The best document I've seen so far was the US study that Unreasonable found, but it is very limited in both targets and weapons.

 

I did not find it - forget who did, I just used it for one series of tests.  The range of weapons/rounds is actually pretty good, from .50 cal API up to 37mm HE. Once you deconstruct the numbers to look at the effectiveness of hits on engine, fuel tanks, pilot and structure separately, for the two planes and aspects tested, you have over 100 data points from which you could build a model for other weapons/ammo and targets. Certainly better than just guessing, at least for HE damage. 

 

But it does not help on this topic. It is missing the rifle calibre rounds and any pure AP rounds.  Also, the report only gives the probability of kills from independent hits, with the exception of some fuel tank compound hit data.  It does not address aerodynamic degradation at all, unless it was so severe that the target was judged not flyable.

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17 hours ago, unreasonable said:

As for this constant mention of "derailment" that we see in this and other threads. I find it interesting that posts that are wrong in fact, are not criticised for "derailment", while posts pointing out those errors are so condemned.  So it is clear what "the rails" actually are: a fixed route to one desired destination, not an open discussion on the topic.  Much easier to claim a consensus in "the community" if dissenting voices are absent. 

 

You've always been a great addition to these threads. I think one thing to understand is that people aren't just plucking this opinion out thin air (although it can certainly feel like it). There are hundreds of guncams and even more AARs that show and describe a type of damage that we simply aren't seeing in the sim. What people are trying to work out it a way for us to get to the point and the way to do that is to find data that shows how it's possible. We have a hypothesis that we're trying to prove it. 

 

We now understand that .50s wouldn't cause that much damage against purely aircraft skin <70 degrees. Unfortunately >70 degrees there is a level of randomness that means we're unlikely to see an actual model based off of it. 

 

17 hours ago, unreasonable said:

.50 cal AP would stay as it is, there would be an API shell doing perhaps ~50-100% additional surface damage, plus higher % chance of igniting fuel,

This I'd disagree with. API is an inferior round to the AP in terms of kinetic energy delivery and penetration. A munitions report actually states B17 pilots didn't like the addition of API as they were less effective against the more armoured front section of the plane. Earlier in the post there was was P51 AAR where a pilot complains about the lack of "pieces coming off" associated with the AP. API was so effective because fire means the plane is going down and the pilot is definitely going to want to get out very quickly. The ignition is not just confined to hitting the fuel tank either, hence why you read a lot of AARs describing parts of the plane smoking after hits. 

 

Question is, how do we understand why this "pieces flying off" is happening and build it into the DM. 

18 hours ago, sniperton said:

image.thumb.jpeg.3a82f64f04e85a73016544aacbd4e78e.jpeg

The hit on the tail is obviously an example of not leaving a nice neat hole. But again, that doesn't prove anything. 

 

@QB.Shallot

There's a good forum post on ww2aircraft.net but it is also mostly B17s with flak damage. A few of note:

 

This is the other side of the "famous one". A He111 brought down by what appears to be cannons and rifle calibre.

 

tumblr_nid9gvjbYv1tcucayo1_1280.jpg.cb1be9543f6a1750fbf2ca0db724fa43.jpg

 

P40 hit by 20mm

 

79Th_Fighter_Group_Based_At_Capodichino_Italy_pilot_Examines_his_Damaged_P-40.thumb.jpg.8acf407051dd51217d90ea9bdffa0ca9.jpg

 

Spitfire hit by 20mm and what appears to be MG17

 

1072073305_SpitfireMkIIbP8342UZ-N_2.jpg.44dcb5aef807b9fdbee4579cad47e466.jpg

 

 

Here's the interesting one. This is a He111 from KG55 that were originally stationed in the Western Front during BoB, but those are definitely not .303s. They spent the remainder of the war on the Eastern front which would mean these are either SsVAK 20mm or 12.7mm (.50 Call). I'd side with these mostly being 20mm but some of the gashes look like they are potentially from smaller rounds. 

 

He111_G1FT_KG_55.thumb.jpg.4d46739ab0ffefdceac38fb500dda0e9.jpg

 

Of course these are all moot points as unless we come across some archive of downed Luftwaffe planes before the use of API.

 

 

 

Edited by Cass
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@Cass Thank you kindly for sharing. I suppose the trouble then is always lack of detail. Like with the third picture picture, are the holes in the tail and fuselage caused by fragmentation, or hits from a smaller caliber weapon? My brain is to small to contain such grey area. 

 

If I could get my hands on a .50 and some reconstructed 109 wings I'd love a chance to see what actually happens. One can dream. 

 

I will make a note that when API was used, (I'll try and find the AAR at some point) pilots noticed a lack of debris coming off from the aircraft when compared to using standard AP slugs, but stated that the increased ability to light targets on fire made API the far superior ammunition, regardless of its perceived reduction in structural/skin damage. 

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9 hours ago, unreasonable said:

 

I did not find it - forget who did, I just used it for one series of tests.  The range of weapons/rounds is actually pretty good, from .50 cal API up to 37mm HE. Once you deconstruct the numbers to look at the effectiveness of hits on engine, fuel tanks, pilot and structure separately, for the two planes and aspects tested, you have over 100 data points from which you could build a model for other weapons/ammo and targets. Certainly better than just guessing, at least for HE damage. 

 

But it does not help on this topic. It is missing the rifle calibre rounds and any pure AP rounds.  Also, the report only gives the probability of kills from independent hits, with the exception of some fuel tank compound hit data.  It does not address aerodynamic degradation at all, unless it was so severe that the target was judged not flyable.

The only problem I have with the study is that the targets they chose (P-47 and B-25 IRRC) are not Axis planes.    I could accept results for the two engine bomber as typical, but to derive results as typical for fighters from a P-47 is more of a stretch since it is about twice the size of anything else, especially the 109 and Spitfire, and generally regarded as a very tough target.  (As well as the weapons you mentioned.)  A similar mid-war German study, if one exists, would probably help us greatly.

 

https://apps.dtic.mil/dtic/tr/fulltext/u2/a179871.pdf 

 

This article (that I have posted before) does seem to point to sources in the German military somewhere as evidenced by the the following quote on page 4.

 

"German experience showed that it took 50-100 hits with 12.7mm (.50 in.) projectiles to down a B-17. By way of comparison, they obtained similar results from only 18-20 hits with 20mm high explosive (HE) projectiles, or four hits with 30mm HE projectiles. (15:44)"

 

The references (15:44) seem to point back to this magazine article:  15. Marsh, Roger. "Mauser MG-213 Cannon." Aviation Ae, Vol. 18 (August 1952), pp. 44-45.

 

I'm assuming if someone could trace that back to original German source we may have something.  It may be cited in the magazine article.

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52 minutes ago, BCI-Nazgul said:

"German experience showed that it took 50-100 hits with 12.7mm (.50 in.) projectiles to down a B-17. By way of comparison, they obtained similar results from only 18-20 hits with 20mm high explosive (HE) projectiles, or four hits with 30mm HE projectiles. (15:44)"

Is the Magazine article misquoting when its states 12.7? At the time wouldn't the only HMG in German service have been the MG131's firing 13mm rounds. By that point should have been API belts.

 

So if this could be sourced, it would be a useful document for comparing MG131 to 20mm damage, but since there's so much disagreement on how similarly the M2's and 131's act, the source couldn't be extended to cover that base. 

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Anyone able to dig out the USAAF microfilm this comes from?

 

1604702513785.thumb.png.98588f406516890f9ed425d438f8a308.png

 

How we reach something like this I don't know. Clearly we shouldn't have the .50 as a singilarity doing decent amounts of skin damage as that's been proven false. We've seen the absurdity of upscaling 12.7mm HE on the P47 and P51.

 

 

But there needs to be a way of creating some kind of skin damage to denote the tearing hits we see and read about.

Perhaps adding a "ghost" HE shell every 5 or 8 rounds to signify a more significant hit.

 

Of course we'd need Mg calibre HE sorted but it would at least be a stop gap to increase their effectiveness relative to the current implementation of other weapon platforms.

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@Cass

Can you provide anymore context to what that page is explaining?

 

As for an interim solution, I think the first concern should be fixing the overblown damage of HE tipped HMG's. I'd say those are 'broken' while the M2's are merely undermodeled. 

 

A fix to AP ammo in general would be better than using an already broken mechanic as a stop gap. I don't know how stat based or "sim" based their damage model is, but I hope that with some tweaking, they can bring the damage for AP HMG's in line with what's been reported in various AARs. People like to say adding API would fix the issue, and while it would reduce peoples perception of the problem as you'd be setting fire to bandits left and right, the core under modeling of the round in certain aspects would still be present. 

 

 

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