Thoughts on the aerodynamic penalty for .50" cal hits.

[SAS_Storebror]

1 hour ago, Aurora_Stealth said:

Would be good if we could see how a MG 131 (13x64B) API round would stack-up against the (shown) .50 calibre API (12.7x99). Unfortunately the former is missing from the first table.

 

The intermediate AP / HE round shown for the MG 131 seems neither here nor there

 

Maybe we're reading the tables differently, but to me the table lists specific values for both types of projectiles, ap and he.

The ingame belting for 109 and 190 guns seems to be 2xHE + 1xAP, and for the He 111H-16 turret 1xHE + 1xAP.

 

Mike

[Aurora_Stealth]

You're absolutely right Storebror, thanks for correcting me - I misread that when glancing through.

 

That makes sense now, it looks like on second look that the MG131 didn't have a straight incendiary (API) round but did have HEI (high explosive incendiary - Brandsprenggranate) rounds.

 

Its quite an obscure gun to be honest, especially as there are none left functioning today... the engineers seemed to have gone off in a very curious direction - much lighter weight and compact size being ideal to fit into the nose of an aircraft. However seems ballistically weaker than the .50 calibre on paper, yet by using special ammunition types like HEI rounds it probably compensates quite a bit by giving an explosive punch and then ignition to anything flammable its punched through.

 

And like you highlighted, there were straight AP or HE rounds as earlier alternatives that could be mixed into the belts.

 

Cheers,

[unreasonable]

And that is why a single figure comparison is not helpful in the context of comparing game damage, whatever you think about the methodology behind that particular article.  What we should expect to see is that while MG131 bursts have more effect against aircraft skin,  as they indeed do, .50 cal bursts have more effect against any hard object like an engine or any component protected by armour.  But has anyone actually tested that? I certainly have not seen it posted.

 

If we know the He111 H-16 uses HE and AP then it should be fairly easy (but time consuming) to do comparisons firing the turret guns of the He and A-20 at various components on the ground. 

 

 

 

Edited July 24, 2020 by unreasonable

[JG13_opcode]

On 7/23/2020 at 12:50 AM, BCI-Nazgul said:

My guess is that there probably is a statistical relationship of some kind, but I'm not going to spend the time to try to do all that research and math.

 

I'm sure there's a statistical relationship of some sort too, but the fact that your memory happens to match the figure from a heavy bomber divided by an arbitrary meaningless constant doesn't mean you should present it as fact.  Moreover I think you misunderstood what unreasonable wrote, because you argued with me earlier that 14 hits to the wings should have brought down my Bf 109, but unreasonable's arithmetic predicts (rightly or wrongly) an average of 62 hits to the wings or fuselage (and that's for a P-47).

 

I get it:  the 50 cal in game doesn't feel the way it's represented in media and in historical anecotes.  But you're ascribing meaning to something that has none.

Edited July 24, 2020 by JG13_opcode

[HR_Zunzun]

US Navy in some study during ww2 made the comparison between 0.50 and 20mm (hispano) and conclude that 1 hispano was equivalent to 3x0.5. In the german paper it takes 20x 20mm to down a b-17 while it took 50 to 100 of 0.50. So that is a relationship of 2.5 to 5 (avg 3.75). More or less on the same ball park. So, for example, a p-47 had the equivalent destructive power of 2,6 hispano (a mustang is two). And do not forget that everytime you hit with the p-47 you do it with 4guns (as we have point converngence and the guns are very near to each other).

Do they keep this relationship in the sim?......

[unreasonable]

2 hours ago, HR_Zunzun said:

US Navy in some study during ww2 made the comparison between 0.50 and 20mm (hispano) and conclude that 1 hispano was equivalent to 3x0.5. In the german paper it takes 20x 20mm to down a b-17 while it took 50 to 100 of 0.50. So that is a relationship of 2.5 to 5 (avg 3.75). More or less on the same ball park. So, for example, a p-47 had the equivalent destructive power of 2,6 hispano (a mustang is two). And do not forget that everytime you hit with the p-47 you do it with 4guns (as we have point converngence and the guns are very near to each other).

Do they keep this relationship in the sim?......

 

Which German paper discusses how many .50 cal hits to down a B-17? Which US Navy Study? Please identify your sources.  

 

The overall effectiveness comparison, even if a useful rule of thumb, does not change the fact that HE shells tend to down their targets in a different way to ball/AP, whatever gun they are fired from.  Your tests and complaints are only with respect to damage to wing surfaces. You have not made any tests of their effectiveness on pilots, engines or fuel tanks, therefore you cannot say anything useful their overall effectiveness in the game.  

 

 

[HR_Zunzun]

7 hours ago, unreasonable said:

 

Which German paper discusses how many .50 cal hits to down a B-17? Which US Navy Study? Please identify your sources.  

 

While I cannot find the original source, the quote comes from Anthony Williams and his book "Flying Guns of World War II". Regarding the german one I think nazgul has already provided a source.

 

7 hours ago, unreasonable said:

 

The overall effectiveness comparison, even if a useful rule of thumb, does not change the fact that HE shells tend to down their targets in a different way to ball/AP, whatever gun they are fired from.  Your tests and complaints are only with respect to damage to wing surfaces. You have not made any tests of their effectiveness on pilots, engines or fuel tanks, therefore you cannot say anything useful their overall effectiveness in the game. 

 

Yes, it is only a rule of thumb but nonetheless relevant as it was based in their respective operational experiences.

To be clear, I didn´t use this comparison as proof of the poster initial conclusions. It was  an answer regarding the relationship between 0.5 browning and 20mm cannon. In any case, I think it adds to the overall discussion.

 

The problem with DM is that is very difficult to find unambiguous rigorous tests. Even the "Airplane vulnerability and overall armament effectiveness" that you have quote many times has its own quirks. It is as much a study of the sturdiness of the p-47 (and b-25) to different ammunition as it is of the effectiveness of this same ammo in general. For comparison, the relationship in weight and wing surface area of a p-47 to the one of a 109 is roughly the same that are in between the p-47 to the b-25. They seem to be in different categories regarding “ammo absorbing mass”. So the results yielded in this study can only loosely translate to the effect they will cause on a 109 (the usual target of M2 ammo). Regarding the wing of a mustang is more comparable to a p-47, but the paper indicates the P of downing the plane (A or B kill) no aerodinamyc losses in such a plane so, again, not all that relevant.

Do not get me wrong. I do think it is a extremmely good test, probably as good as we ever going to get regarding ww2 planes but DM is an extremmely complex subject and all test are going to be inevitably limited.

 

Coming back to the original poster test and conclusions, I think that it showed that there is a problem with the DM (or specific ammo) if you can empty the whole 0.5 ammo of a p-39 in a -51 wing, with reasonable accuracy, and the mustang as a result is not, at least, struggling to remain in 1G level fly.

[unreasonable]

19 minutes ago, HR_Zunzun said:

 

 

Coming back to the original poster test and conclusions, I think that it showed that there is a problem with the DM (or specific ammo) if you can empty the whole 0.5 ammo of a p-39 in a -51 wing, with reasonable accuracy, and the mustang as a result is not, at least, struggling to remain in 1G level fly.

But that is just the point - the test showed nothing of the kind. Most of the shots missed altogether, and those that did hit mostly hit aileron or flap, not the wing.  And when there were eventually enough hits to get level two damage - there was an obvious and immediate decrease in speed visible in the cockpit by looking at the instruments.

 

I also find it odd that you chose the P-51 for this test - to start with, how many people fire at P-51s with .50 cals in MP?  (Actually quite a lot given my experience of rife team killing in MP - but I am sure you take my point).  The P-51 is known for it's damage resistance in BoX,  presumably you know that. Why not test against a Fw190 or 109 wing?

[HR_Zunzun]

13 minutes ago, unreasonable said:

But that is just the point - the test showed nothing of the kind. Most of the shots missed altogether, and those that did hit mostly hit aileron or flap, not the wing.  And when there were eventually enough hits to get level two damage - there was an obvious and immediate decrease in speed visible in the cockpit by looking at the instruments.

 

I also find it odd that you chose the P-51 for this test - to start with, how many people fire at P-51s with .50 cals in MP?  (Actually quite a lot given my experience of rife team killing in MP - but I am sure you take my point).  The P-51 is known for it's damage resistance in BoX,  presumably you know that. Why not test against a Fw190 or 109 wing?

Well, if it hit the aileron or the flap then is hitting the wing. Not only because it is part of it (at least in my limited knowledge on aerodynamics) but also because, once it hit them, it´ll most likely carry on forward (aileron and flaps are not armoured structures) and will exit out of and damage some of the wing ahead. Wouldn´t it?

I didn´t look at the track in detail and I seem to be unable to get it know. But, considering that the P-39 carries 200rpg and in ideal condition (closed, behind and with cooperative target) a 5% hit prob (and likely 10%) can be achieved, then something between 20 to 40 rounds could have reached the wing. It is my uneducated guess that at least the assymetrical drag caused by the dozens of entry and exit holes would be enough to make the pilot strugle to maintain coordinated level flight.

 

By the way, I am not part of the original posters so can´t answer about the choice of the mustang wing. In my opinion a 109 wing would have been better but, in any case, the comparison they made with other guns in the same category (the german 13mm and the berezin) makes the test still valid in my eyes.

[unreasonable]

I accept the point about hits to aileron and flap not necessarily passing through - I just do not know enough about the details of the DM to say what is happening or why in that case. My guess is that this is just a DM limitation - there is only so much hit recognition the program can handle. But that is just a guess.

 

What both the OP's test and my tests firing at He111s show, however, is that if you get level 2 or more surface damage graphics on a wing hit box - not flap or aileron - you get a lift/drag penalty.  So the thread title is factually incorrect.  .50 cal hits can and do create aerodynamic penalties. The problem is that he only got that level of damage right at the end of the test. I got it in an He111 outer wing section with less than one box of .50 cal. Less than one box because I also got severe damage to the aileron.  All I am asking for here is accuracy in the claims. 

 

To compare .50 cal with the MG 131 here are two static firing missions where anyone can do that precisely - and also compare 20mm FF and MG 81. If someone was so inclined they could check how many hits are required to create the different damage graphic levels, and/or detatch wing sections. You can also test how many hits needed to kill the pilot, stop the engine etc, after minor changes to the mission reorienting the target planes in the ME if necessary.   

 

It appears to me that the MG FF and possibly MG 131 are firing alternate AP and HE rounds, but if someone has unpacked the files they could confirm this. I am just going by the graphics, trying to fire as close to one shot at a time.  Note that the different wing hit boxes are not equally damage resistant - the outer ones take far fewer hits to show damage.

 

Checking that these missions work, my concern is not so much the .50 cals, which I find entirely plausible, but the HE rounds. Something that always bothered my in the BoX DM is the ability of even small HE shells to damage components over a wide area, and you see it again here.  I am not convinced that a MG 131 or even 20mm HE (even with mineshells) should almost always wreck the skin of not just the hit box where it impacts, but also adjacent ones, yet my preliminary checks indicate that this usually happens. This is not a firm conclusion - I am happy for someone else to do the work of enough repetitions to come up with a convincing average.  

 

He111 h16 static test vs P47.zip

A-20 50 cal static test vs P-47.zip

 

If anyone has trouble making the missions work let me know - unzip in your missions/my missions folder and you should see them under these names. Make sure throttle is in neutral then switch firing positions and take control of the dorsal turret in the A-20 or side, rear or front guns in the He111. You can then shoot at the target. To change the target open mission in ME and change the model, make sure that you press the "on the ground" button, resave. 

Edited July 25, 2020 by unreasonable

[-SF-Disarray]

The video posted back on page 2 by Ewoksithlord shows German planes being hit by .50 AP ammo. Watch that if you want to see what it does to German planes. It falls in line with our testing and general observations. It is even non-multiplayer data. The G-14 test sample is of particular note. Large sections of the wing are removed and there is no observable change in the plane's orientation relative to the horizon and no obvious control input from the bot to maintain that orientation. Then the wing falls off. An interesting follow on test would be to produce this kind of damage to a G14 and then stop shooting and see for how long this plane can maintain both stable flight and formation with the other, undamaged planes. This is later contrasted by the demonstration of a cannon impact. The D-9 footage shows similar behavior, though it could be argued that there are power setting changes indicated by the increase of exhaust smoke; this is why I don't like using bots for this kind of test as there is no way to know exactly what is happening with the tools I have available.

 

As to why the 51 was chosen as a target for this particular instance of testing: Initially we thought this might have been something tied to the flight/damage model of an individual plane, the 109. We were talking among ourselves and began to wonder why 109's in particular were so capable of absorbing fire and carrying the fight. So we did tests with various target planes planes, a 109-G14, a P-40, a P-39 and a P-51 were all used at various points of testing, using a P-51 as the shooting plane, and found the same results each time, eliminating the target plane as a variable, at least as far as fighters are concerned. Ultimately this means the P-51 was chosen in the tests tracks that were posted for no particular reason and as far as I can tell it would make no difference to the results if you put any other fighter in the place of the P-51. We didn't think to utilize any bombers or attackers in this testing so while I can't say with certainty the results would be similar, I suspect that they may be.

 

This led us to wonder if it was the guns, specifically the ammo, that was causing the issue. We then switched out the plane doing the shooting to isolate the number of guns in a comparative test of various guns, specifically the M2, the MG131 and the UBS 12.7 mm. The tracks posted were from this last batch of tests comparing equal number of guns and their effectiveness against the same target. So the P-39 was chosen for the number of guns and configuration of those guns being the closest match to the other planes used, a 109-G14 and a Yak-7; all the planes have 2 HMG set into the nose of the plane. The 131 and UBS guns performed remarkably better than the M2's. That is how the tracks we posted came to be.

[357th_KW]

4 hours ago, unreasonable said:

It appears to me that the MG FF and possibly MG 131 are firing alternate AP and HE rounds, but if someone has unpacked the files they could confirm this. I am just going by the graphics, trying to fire as close to one shot at a time.  Note that the different wing hit boxes are not equally damage resistant - the outer ones take far fewer hits to show damage.

 

Checking that these missions work, my concern is not so much the .50 cals, which I find entirely plausible, but the HE rounds. Something that always bothered my in the BoX DM is the ability of even small HE shells to damage components over a wide area, and you see it again here.  I am not convinced that a MG 131 or even 20mm HE (even with mineshells) should almost always wreck the skin of not just the hit box where it impacts, but also adjacent ones, yet my preliminary checks indicate that this usually happens. This is not a firm conclusion - I am happy for someone else to do the work of enough repetitions to come up with a convincing average.  

The MG/FF is definitely belted, with AP and I believe both an HEI and the Mine shells.  What the exact pattern is I can’t say, but it’s obvious when shooting at pilot armor, where the shells that don’t explode easily punch through and one shot the pilot, while the exploding shells often cannot.

In my very extensive static testing in 4.006 I saw odd issues with the area of effect of the MG/FF.  I gave up on testing with it fairly quickly because the results became so unpredictable that it was difficult to draw much of a conclusion and was quickly becoming a giant time-suck.  On the P-51 for instance I was trying to test how many rounds it took to ignite the fuselage tank from a side angle with the 20mm - within a few rounds I’d end up with one or more wing tanks or the engine on fire, often before I could get the fuselage tank burning.  When doing fuel tank testing on the B-25 (trying to simulate the US ordinance tests) I was shooting at the right wing tank between the fuselage and engine, and about 1/3rd of the time the LEFT wing tank was catching on fire at the same time as the right tank.  That would require fragments passing through two walls of the fuselage, and then into the wing tank with enough force and heat left to defeat the self sealing tank and start a fire.  

[unreasonable]

That was rather my experience with testing the P-47 vs 20mm HE LAA a while back - HE fragmentation damage seemed implausibly wide.  I did not try to test individual components though, just getting a reasonably random spread of hits from the same angle as the US report used and assessing the overall results in terms of how many hits were needed to get kills, and what element was the cause.  On average it took about half as many hits in the game as in the report.  That was running the test 100 times!

 

Whether you blame that on the P-47 being half as robust as it should be, or the 20mm HE shell being twice as powerful, or a combination of the two requires a comparison between planes - done using the airfield attack test. That indicated that the P-47 was unusually vulnerable, especially to hits to engines, although not enough to explain the full difference between test and US report conclusions.

 

Hence my general conclusion that HE hits were over-modelled. (For which I got abused by some of the MS crowd.... )  This was a few DM iterations back and I do not think the same tests are even possible now in any reasonable timescale, now that the ground gunner AI has been made much more unpredictable in how long it takes to wake up.

 

All that aside, it should be easy enough to count hits required to get a given hit box to show level 1-2-3 damage graphics using a static test. I am just not inclined to do it myself at least until the present iteration of DM changes (fuel system etc) is complete.   

 

Edited July 25, 2020 by unreasonable

[-SF-Disarray]

While this is ranging rather far afield from the topic I suspect you may be correct that the effects of HE detonations are over modeled. Perhaps not in power but in area of effect. I have observed many times a hit from a 20 mm round, and even 131 rounds, causing damage along the entire length of a wing. Looking at photographs of damage caused by these weapons it seems like it should be much more localized to the point of impact. This could play into the topic of discussion as well, the difference between HE and AP hits in HMG's is very pronounced and seemingly exaggerated which could lead to an impression that the AP rounds are having an insufficient, or no, effect. Comparisons aside, I still feel there is enough evidence to suggest that the .50 AP rounds lack the appropriate effect in terms of aerodynamic impact.

[QB.Shallot]

6 hours ago, -SF-Disarray said:

I have observed many times a hit from a 20 mm round, and even 131 rounds, causing damage along the entire length of a wing.

This is because visual damage is not representative of the actual damage that the aircraft experiences within the DM. This was made clear by the devs when the new DM rolled out. Visual damage being more accurately modeled would require the dev team to use a lot of time and effort that I assume is currently being aimed at the BoN expansion. 

[unreasonable]

22 minutes ago, QB.Shallot said:

This is because visual damage is not representative of the actual damage that the aircraft experiences within the DM. This was made clear by the devs when the new DM rolled out. Visual damage being more accurately modeled would require the dev team to use a lot of time and effort that I assume is currently being aimed at the BoN expansion. 

 

If an engine stops or there is a fuel leak after a 20mm hit on a wing, that is not a visual graphic issue - it is real systems damage. Even for skin damage, the issue is whether damage to one hit box should also show up as damage on another hit box - which is also actual damage with real effects. We are not just talking about the location of hit damage graphics within one hit box, where your point is valid.

 

BTW, my test of .50 cals vs AI planes flying at full speed also works on fighters: there is clear evidence of an aerodynamic effects. These two F4s started side by side flying to the same distant waypoint set for top speed. The screen shot is about twenty seconds after I finished firing one box, not all of which hit.

 

 

 

[JG13_opcode]

Seems pretty conclusive to me.

[-SF-Disarray]

1 hour ago, QB.Shallot said:

This is because visual damage is not representative of the actual damage that the aircraft experiences within the DM. This was made clear by the devs when the new DM rolled out. Visual damage being more accurately modeled would require the dev team to use a lot of time and effort that I assume is currently being aimed at the BoN expansion. 

 

I'm speaking less of the actual visuals and more to the effects of a 20 mm round appearing across a whole wing. If you shoot a wing with AP rounds of any kind you can find there are multiple, for lack of a better term, hit boxes where damage can be applied. If a 20 mm round hits a wing tip, for example, one would expect the damage to be localized to that hit box but that isn't what is happening. The damage can often extend all the way to the wing root. I know the reasons why we can't have 1:1 representation of damage dynamically applied to planes and frankly the effort that it would require to put into effect could be better applied elsewhere.

 

Do you have a track of this test? Or a video?

[unreasonable]

2 hours ago, -SF-Disarray said:

 

I'm speaking less of the actual visuals and more to the effects of a 20 mm round appearing across a whole wing. If you shoot a wing with AP rounds of any kind you can find there are multiple, for lack of a better term, hit boxes where damage can be applied. If a 20 mm round hits a wing tip, for example, one would expect the damage to be localized to that hit box but that isn't what is happening. The damage can often extend all the way to the wing root. I know the reasons why we can't have 1:1 representation of damage dynamically applied to planes and frankly the effort that it would require to put into effect could be better applied elsewhere.

 

Do you have a track of this test? Or a video?

 

Was that question for me? If so not at the moment, I just reformatted the mission quickly to see if it could work with firing at fighters. A bit tricky because of the A-20 vs F4 speed difference, when you give the F4s their top speed waypoint, but doable if you set the game to half speed. It could probably be made easier with some slight repositioning of the planes to give a closer shot. You do not have very long to get into the dorsal firing position and take control of the gun before the fighters overtake.

 

Apart from changing the plane model and the waypoint speed plus a little fiddling with the plane positions, the mission is the same as in the firing at He111s mission I posted in the other thread.     50 cal vs 109F4 test A20.zip

 

I have no intention of making videos. I could post a track but to be honest it is always much better to perform these tests yourself if you are sceptical about the results. 

 

 

[BCI-Nazgul]

15 hours ago, unreasonable said:

 

If an engine stops or there is a fuel leak after a 20mm hit on a wing, that is not a visual graphic issue - it is real systems damage. Even for skin damage, the issue is whether damage to one hit box should also show up as damage on another hit box - which is also actual damage with real effects. We are not just talking about the location of hit damage graphics within one hit box, where your point is valid.

 

BTW, my test of .50 cals vs AI planes flying at full speed also works on fighters: there is clear evidence of an aerodynamic effects. These two F4s started side by side flying to the same distant waypoint set for top speed. The screen shot is about twenty seconds after I finished firing one box, not all of which hit.

 

 

 

Was that test created online or offline?  We have not seen that damage view online in our tests and I've never seen damage like that online during my playing.

Edited July 26, 2020 by BCI-Nazgul

[QB.Shallot]

@-SF-Disarray @unreasonable,

I'm not entirely sure if your points actually stand true.

I don't have a lot of time atm, but I did some quick testing. There doesn't seem to be a graphical texture for "heavy aerodynamic damage" that only applies to a portion of your wing. Now I will note this testing was pretty rough, so I'm not claiming it as the holy truth. If either of you have a picture of localized "heavy aero" damage that only applies to a portion of the wing, I'll happily accept defeat. 

 

I've proven myself incorrect. It is possible for heavy damage textures to be applied locally. My mistake. \

However, it appears that HE rounds, regardless at how low yield the shell is, will apply moderate-heavy damage textures. The fact that both the UB machine gun and the German 13mm's apply heavy damage textures so easily compared to the .50's makes this fact pretty clear.

Edited July 27, 2020 by QB.Shallot

[RedKestrel]

58 minutes ago, QB.Shallot said:

@-SF-Disarray @unreasonable,

I'm not entirely sure if your points actually stand true.

I don't have a lot of time atm, but I did some quick testing. There doesn't seem to be a graphical texture for "heavy aerodynamic damage" that only applies to a portion of your wing. Now I will note this testing was pretty rough, so I'm not claiming it as the holy truth. If either of you have a picture of localized "heavy aero" damage that only applies to a portion of the wing, I'll happily accept defeat. 

 

I've proven myself incorrect. It is possible for heavy damage textures to be applied locally. My mistake. \

However, it appears that HE rounds, regardless at how low yield the shell is, will apply moderate-heavy damage textures. The fact that both the UB machine gun and the German 13mm's apply heavy damage textures so easily compared to the .50's makes this fact pretty clear.

I think the basic information the tests show is that it is definitely possible for the fifty cals to cause aerodynamic damage, unlike the OPs assertion. It simply seems to be that the way it is implemented is what causes this impression. With wing mounted guns scattering hits all over a plane, you can encounter scenarios where a plane gets hit dozens of time with no drag. This seems to be what people are seeing. It’s why sometimes when I get good hits I notice immediate speed loss, while others I don’t notice any...it’s just that the hits are too scattered to trigger the drag.

[QB.Shallot]

@RedKestrel,

It has nothing to do with the spread of the guns, just how the game visually represents HE damage, no matter how minimal. 

[unreasonable]

1 hour ago, QB.Shallot said:

@RedKestrel,

It has nothing to do with the spread of the guns, just how the game visually represents HE damage, no matter how minimal. 

 

No. The damage graphics are generic - you can get them through HE and you can get them through ball/AP.  I have seen 20mm HE hits from LAA produce only the minimum "bullet holes" damage graphic more times than I can count while testing LAA.  [Edit - that was with pre 4.008 DM - AFAIK only the amount relative amount of damage has been changed in 4.008, but it is possible that this now means that HE hits always reach stage 2 threshold].  

 

It requires a certain quantity of damage in a particular hit box, that is all, which is why the spread of the hits does matter. If using wing mounted guns [using ball], especially far from convergence, causes you to spread your hits over the wing surfaces you are less likely to get a higher level of graphic skin damage and hence less likely to see a lift/drag penalty. I can get any level of damage using .50 cal provided I score enough hits in a particular hit box.

Edited July 27, 2020 by unreasonable

[unreasonable]

This P-47 was hit by one 20mm Flak shell in my Airfield Defence mission (ver 4.008c). As I hope you can see, the inner wing surfaces look like level 1 damage to me, although this was not the hit location.  The problem - IMHO, without extensive testing of 4.008 DM - is the same that it has always been. Small HE hits (20mm and less) spread extensive damage over far too large an area and are too lethal.  I think severe skin/structural damage should be much more local,  with only very small probability of damage further away, given the limited amount of metal in these shells.

 

[QB.Shallot]

@unreasonableThe spread of the guns is a no factor though. If I'm in a Mustang, I'm just firing 2 different 3 gun streams. It's actually more massed fire power per stream than the 13mm's or single UB machine gun. Those guns produce moderate damage decals within a handful of hits, while the .50's take a far longer squirt. It seems that the minimal damage decal will only occur for the UB and 13mm's if an AP round strike the wing. 

 

Edit: The picture you shared of the ground fire damage shows clear moderate damage to your rear fuselage. The light damage is the splash. What I'm saying is the point of impact will not have level one damage. 

Edited July 27, 2020 by QB.Shallot

[unreasonable]

4 hours ago, QB.Shallot said:

@unreasonableThe spread of the guns is a no factor though. If I'm in a Mustang, I'm just firing 2 different 3 gun streams. It's actually more massed fire power per stream than the 13mm's or single UB machine gun. Those guns produce moderate damage decals within a handful of hits, while the .50's take a far longer squirt. It seems that the minimal damage decal will only occur for the UB and 13mm's if an AP round strike the wing. 

 

Edit: The picture you shared of the ground fire damage shows clear moderate damage to your rear fuselage. The moderate damage is the splash. What I'm saying is the point of impact will not have level one damage. 

 

Understood - and you may be right in 4.008  I have not done enough testing to say otherwise. I can say definitively that under previous DMs you could and did get level one damage at the point of impact, usually tail surfaces, ailerons and flaps from 20mm LAA hits.  P-51s hit in the 20mm LAA test often only showed level one damage anywhere.  So I suspect that the mechanism still allows this, but the amount of damage being done has been increased so you do not see it anymore.

 

As to the number of .50 cal hits required - in both my He111 test and the F-4 test I fired one box of .50 cal from the A-20 - 30 rounds, according to the ammo counter, that is all. In each case I got damage on at least two hit boxes per target plane, which slowed down. 

 

Here are pictures from static test of A-20's .50 cal against P-47 wing.  One box used. I took the shot when I reached each damage level. Ammo counter on the left.

 

 

Edit - note that this is at 20-30m range, so if the DM is determining damage applied for solid shot based on impact kinetic energy + (RNG?), then at longer ranges more hits are required for the same quantity of damage. ~ 50% more at 500m  twice as many at 250m and ~ three times as many at 500m, more when flying fast.  whoops! wrong ballistics preset.  I am sure someone can work that out exactly. 

Edited July 27, 2020 by unreasonable

[357th_KW]

With regard to 13mm compared to .50cal here's some resources:

 

https://ww2data.blogspot.com/2017/05/german-projectiles-792mm-to-30mm.html

 

https://www.inetres.com/gp/military/infantry/mg/50_ammo.html

 

The 13mm had an HEI and an HEI-T, as well as an AP-T.  In all cases it was a lighter projectile at a lower velocity then from the US .50, with significantly less armor penetration.  Chemical payload as compared to an American API or API-T was similar in weight.  Roughly 18 grains of PETN for the German round vs. 15-27 grains of incendiary compound on the M8 API or M20 API-T. 

 

Here's a video showing some small quantities of PETN - it's not gonna do much beyond lighting fires:

 

[SAS_Storebror]

Nice find @KW_1979, thanks for sharing!

 

Mike

[BCI-Nazgul]

On 7/27/2020 at 1:18 AM, KW_1979 said:

With regard to 13mm compared to .50cal here's some resources:

 

https://ww2data.blogspot.com/2017/05/german-projectiles-792mm-to-30mm.html

 

https://www.inetres.com/gp/military/infantry/mg/50_ammo.html

 

The 13mm had an HEI and an HEI-T, as well as an AP-T.  In all cases it was a lighter projectile at a lower velocity then from the US .50, with significantly less armor penetration.  Chemical payload as compared to an American API or API-T was similar in weight.  Roughly 18 grains of PETN for the German round vs. 15-27 grains of incendiary compound on the M8 API or M20 API-T. 

 

Here's a video showing some small quantities of PETN - it's not gonna do much beyond lighting fires:

 

The quantity was not specified unfortunately.  Also, I have a feeling that result in a confined .50 round hitting at full force would be different than these tests.

[-SF-Disarray]

The hammer test is probably the closest approximation, even though the quantity is probably lower than the .9 to 1.9 grams used in these rounds. It would be interesting to see live footage of these rounds impacting. I did a bit of searching but couldn't come up with anything that didn't have a lot of other stuff mixed in with the HE filler and even that didn't make much of a bang.

[the_emperor]

8 hours ago, -SF-Disarray said:

The hammer test is probably the closest approximation, even though the quantity is probably lower than the .9 to 1.9 grams used in these rounds. It would be interesting to see live footage of these rounds impacting. I did a bit of searching but couldn't come up with anything that didn't have a lot of other stuff mixed in with the HE filler and even that didn't make much of a bang.

 

Here you can see the MG131s of a FW 190A8 vs a La-5. But by 1944 the HE round was already phased out in favour of the pure incendiary round. (the videos will start at that specific point)

 

 

Edited July 31, 2020 by the_emperor

[Barnacles]

If you assume:

1. The 20mm mine shell makes a 70cm wide hole. (apologies I couldn't find it, but there was a reference giving the wingspan of this wing, by measuring it the hole for the 2cm shell was 70cm)



2. A 50cal AP hole is always .50" wide (diameter). This assumes just ONE neat entry hole.

The ratio of area between a mineshell hit and a 50 cal hit is 0.38485/0.00013= 2960 (rounded)
Ie the mine shell leaves a hole 1255 times bigger than the 50 cal.

A simple assumption would be to assume the decrease in lift and increase in drag would be 1255 greater in the case of a 20mm hit.

Now if you assume that the 50 cal makes a simple half inch wide exit hole as well  the ratio becomes 1480



NAs you can see from the above photos, the exit holes from 50 cals are not .5 inch wide. I think it is reasonable to assume they are somewhere near the size of a filler cap or a fist, which I'll assume is about 12 cm
So 0.38485/(0.00013+0.01131) 34
Is the new ratio. IE. ASSUMING 1. The 20mm mine shell makes a 70cm wide hole (seems reasonable) and a 50 cal makes a .5 inch (12.5mm) entry hole and a 12cm wide exit hole (estimated from the pictures)

So in game if we saw about the same speed loss for 60 50 cal API hits as for one 20mm mine shell hit, it would match my estimations above.
I know I haven't factored in an exit hole for the mine shell, because the disadvantage with the mineshell is that it doesn't create large shrapnel fragments. 

From in game testing you saw a 65kmh reduction for one mine shell and slightly less than 20kmh for 60 x 50 cal hits. 
In game the number seems to be around 200

My conclusions are:

The game *could* be an almost perfect fit, but only if you assume on average you get exit holes 3 times the area of the round's cross section. That seems the low end of reasonable to me. Also,  I feel the 20mm damage was representative, (you can see historical evidence of bigger and smaller holes) it certainly is possible to see panels dislodged by them (but so can 50s) and for what it's worth there are some mineshell photos where the holes caused are not 70cm (over two feet!) wide. There several photos of confirmed 20mm mine shell hits  which are around 30cm wide. Obviously these could be subject to survivor bias, but when you consider it generally took 5-6 20mm mine shell hits for airframe loss, it is not reasonable to say that 1 or 2 hits on a returning airframe would necessarily be sub typical in size.
I therefore think that the aero damage should be increased by around 300-600% for 50 cal hits REALATIVE to 20mm mine shells.

This would still not make 50 cals an uber cartoon death ray, but it would make it significant if you got say 10 hits in the wing. At the moment even 20 hits in the wing mean you're still combat capable, whereas a 20mm hit means you're not.



 

Edited August 1, 2020 by 71st_AH_Barnacles
I've changed the numbers because I made a mistake in calculation, but the new calculation still supports my point

[unreasonable]

Much as I like your method, I think the assumption that every .50 cal makes an exit hole, and the 20mm mineshell (or conventional HE) never does, is indefensible.  A HE blast in a thin wing compartment can blow off the surfaces on both sides of the wing.  Typical photos of fighter planes with mineshell damaged (probably) wings and tail surfaces often show large bite shaped pieces missing.   It is not completely clear from the German test picture of a HS124 if there is another hole on the other side of the wing, but it looks to me as though there is.

 

If you were looking at fuselage hits - like the unfortunate shortest lived Spitfire, see link - your assumption might be more reasonable, but still ignores splinter exits. In that case the internal space was too large for the pressure to blow off the surface forwards of the entry point, so what you had was something that looks far more like a conventional HE hit, (indeed it might have been), with an entry hole and a lot of splinter damage in a forward cone  (other side of the fuselage).  This Spitfire, of course, survived in our game terms, although the pilot was wounded - it landed and was written off. If those hits had been to the wing I expect the pilot would have bailed.

 

 

https://imgur.com/a/GrRxX

 

 

 

 

Also not sure about your numbers based on your assumption, I am a bit tired today, maybe making a mess of this. Please correct me if I am getting something here wrong.

 

Working in cm:  

 

20mm shell hole = 70cm diameter, therefore area  = 3.14*35^2 = 3847 cm^2

 

.50 cal bullet hole = 1.27cm diameter, therefore area = 3.14*0.635^2 = 1.266 cm^2

 

Cannon hole is 3032 times as large in area as neat .50 cal hole (counting one side for both).

 

So even if the cannon shell has no exit hole at all (unlikely), and the .50 cal has a nasty exit ten times the size of  neat entry (possible), the ratio would be 3848/(1.266*11) = 276

 

 

 

 

Edited August 1, 2020 by unreasonable

[Barnacles]

31 minutes ago, unreasonable said:

Much as I like your method, I think the assumption that every .50 cal makes an exit hole, and the 20mm mineshell (or conventional HE) never does, is indefensible.  A HE blast in a thin wing compartment can blow off the surfaces on both sides of the wing.  Typical photos of fighter planes with mineshell damaged (probably) wings and tail surfaces often show large bite shaped pieces missing.   It is not completely clear from the German test picture of a HS124 if there is another hole on the other side of the wing, but it looks to me as though there is.

 

If you were looking at fuselage hits - like the unfortunate shortest lived Spitfire, see link - your assumption might be more reasonable, but still ignores splinter exits. In that case the internal space was too large for the pressure to blow off the surface forwards of the entry point, so what you had was something that looks far more like a conventional HE hit, (indeed it might have been), with an entry hole and a lot of splinter damage in a forward cone  (other side of the fuselage).  This Spitfire, of course, survived in our game terms, although the pilot was wounded - it landed and was written off. If those hits had been to the wing I expect the pilot would have bailed.

 

 

https://imgur.com/a/GrRxX

 

 

 

 

Good point.

 

I'd agree that worst case scenario would include damage the other side of a wing. I found the picture of the other side of that spit. You can see the splinter holes are very small, but the pressure has removed a panel.

 

Even then though my 1 : 54  ratio becomes 1: 108 which is still half that seen in the game.

 

Importantly I'm glad I've gone through the process though, because if it is only 50% out in my thought experiment, that's probably closer than my gut instinct was, if I'm being honest with myself.

 

Even so, I still think as much as there's incredible energy in the mineshell blast. There's an incredible amount of KE in 50 cal hits, so at the moment I'm still thinking that the amount of ripping and tearing they do is underrepresented in terms of aero damage. 

 

But it's a case of doubling it, rather than multiplying it by any larger factor, I think.

 

 

Edited August 1, 2020 by 71st_AH_Barnacles

[unreasonable]

Obviously we are cross posting - but see my edit below the pic. One of us has got our original area numbers wrong and I cannot see how you derived yours. 

[Barnacles]

27 minutes ago, unreasonable said:

Obviously we are cross posting - but see my edit below the pic. One of us has got our original area numbers wrong and I cannot see how you derived yours. 

Yeah I'll check.

 

I got 0.63617 square meters for the 70cm mine shell hole because I used 45cm diameter (Doh!, I was tired) instead of 35cm.

And recalculating, I get 0.38485 m^2 for the 20mm round (same as you @unreasonable)
0.00013 m^2 for entry 50 cal (using .25 or 0.635 cm radius) same as you
0.01131 m^2 for exit 50 cal (using 6cm radius)

0.38485   ÷   ( 0.00013   +   0.01131 ) = 1:34 ratio.

Which is less than my original 1:54 number because I fat fingered the calculator (45 instead of 35cm) and actually increased the area of the mine shell hole in my estimation (I'm sure you could get 90 cm diameter holes IRL, esp. with panels ripping off in airflow)

So I'll I'll leave the post up there with an edit.

Edited August 1, 2020 by 71st_AH_Barnacles

[unreasonable]

So we can get a large range of ratios depending on the assumptions, especially about the exit holes. Your estimate for the .50 cal exits is IMHO right at the upper end of what is reasonable, and no exit allowance at all for the HE shell - ratio 1:33 Which must be a minimum.  Allowing an equal sized HE exit and an average exit for 50 cals of ten times the entry area, ratio over 1:500!  

 

Clearly there is a very wide range in which the game could be more or less "right".   TBH I would be more worried about the MG131 and equivalents.  But thanks for doing this exercise - I was thinking about it then decided to take a break....

Edited August 1, 2020 by unreasonable

[Barnacles]

1 minute ago, unreasonable said:

So we can get a large range of ratios depending on the assumptions, especially about the exit holes. Your estimate for the .50 cal exits is IMHO right at the upper end of what is reasonable, and no exit allowance at all for the HE shell - ratio 1.33 Which must be a minimum.  Allowing an equal sized HE exit and an average exit for 50 cals of ten times the entry area, ratio over 500!  

 

Clearly there is a very wide range in which the game could be more or less "right".   TBH I would be more worried about the MG131 and equivalents.  But thanks for doing this exercise - I was thinking about it then decided to take a break....

Yes definitely. You've made me think now that an allowance for the reverse side damage of an HE shell is essential.

If I was writing the DM I would assume my 12cm exit hole for a 50 cal to be the absolute worst case (save for panels being knocked off), but equally I'd say 70cm with an equivalent 70cm hole on the reverse to be the absolute worst case (save for panels being knocked off).

I think the lower end for HE 20mm (save for dud rounds) would probably be between 60 and 45 cm hole with no significant hole on the reverse. and the 50 cal would be just a .50 inch diameter hole.

You're right about the range of assumptions, but I would say.

1. The game is the closest match when you use IMO a high assumption of the damage of a 20mm (70cm hole both sides), and an IMO middling assumption of 50 cal damage (significant exit holes only every 3 hits.
2. In game the engine almost always gives you around a 60kmh penalty for one 20mm mg151 hit. and almost always only gives you a significant 50m cal penalty if part of the wing actually falls off. (This was from testing).
3. I agree with the statement that the systems damage is credible on 50s. They are indeed killers if you get a decent convergence shot. But in terms of effectiveness compared to the German 20mm, they are not even in the same ball park in game. There's nothing of the 3:1 equivalency that the USN declared for 20mm cannon v BMG 50 cals. The US armed forces were clearly aware of the relative performance of their weapons to the enemy, (even though this is a morale boosting propaganda piece) and I think would have at least mentioned it if there was such a disparity.

 

38 minutes ago, unreasonable said:

TBH I would be more worried about the MG131 and equivalents.  

Yeah, that stands out to me as something that's 'wrong'

I think my back of a cigarette packet calculations are as you say saying the game not a million miles away for being a match for 20mm and 50 cal aero damage. But not with 131s.

My gut instinct is HE damage is more credible for the larger rounds, ie 30mm is a kill in 1-3 rounds, as it was IRL. 20mm is 5-6 (close to RL) 13mm can render you unflyable with a handful of hits though, which IMO is a bit fishy.

 

[Creep]

On 5/15/2020 at 11:48 AM, 71st_AH_Yankee_ said:

...consider that the .50s don't just fire AP ammo, but API. I imagine that would do more than just drill a neat hole in a surface. Given this, and the above in the OP, the .50s almost certainly need to have their aero effects increased.

 

Alongside this, of course, it seems very important that API effects also be modeled. Right now the .50s act like they're firing AP slugs only, and that severely decreases their effectiveness. As things are currently modeled, we'd be better off using the VVS .50s, with their mix of AP and HE ammo. Until we have proper aero damage modeled, and the API effects, the .50s will continue to be anemic.

 

I completely agree with this. Explosive damage is modeled which causes a significant amount of damage, but incendiary is not. Until that changes, I think it would be reasonable to use whatever tools are immediately available to the dev team in order to address the concerns of the multiplayer community.