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

[unreasonable]

Just now, the_emperor said:

 

Well, I dont know the detonation speed of the fuze, but so so far there are no hints that indicate, that the shell is deliberately detonated inside plane structure and most of the blast happens when hitting.

I am sure, some of the blast is directed forward, but the round seems to be a combination of Blast/fragmentation (heavier than other 20mm rounds  -> higher frag potential)/incendiary.

It seems to be more of a multipurpose HE/I round since it seems quite effectiv vs unarmourd vehicels and due to its higher fragmentatio  potential also vs personel.

 

My point is that "instantaneous" fuzes are not actually instantaneous. The only one I have been able to find that quantifies the delay is an artillery shell, with an instantaneous delay of 170 micro seconds.  http://www.vxltechno.com/fuzes.htm  POINT DETONATING FUZE PDM 572 C1

 

 A shell travelling at 500 m/s will move 85mm in that time - in other words, if a 20mm shell has the same delay, it will be at least partly and sometimes entirely inside the skin, depending on the angle of the strike.

 

The German drawings you posted earlier show a verzogerung (delay) of 0.75m +/- 0.25m  I would normally take that "m" to mean meters:  that makes perfect sense for a mineshell where you absolutely want it well inside the structure of a heavy bomber. 

 

Note that a certain proportion of HE shells would ricochet and explode outside the skin when they hit at a very acute angle, whatever the fuze, so not all damage pictures will look the same.

[[DBS]Browning]

No doubt it was also common for the skin to fail to cause detonation.

[JtD]

3 hours ago, unreasonable said:

The German drawings you posted earlier show a verzogerung (delay) of 0.75m +/- 0.25m  I would normally take that "m" to mean meters:  that makes perfect sense for a mineshell where you absolutely want it well inside the structure of a heavy bomber.

 

The Germans classified their noze fuzes as instantaneous, but the description include a delay mechanism to "make sure the shells goes off inside". This is how they manage the half meter. Real instantaneous fuzes will be a somewhat faster. But since the all are based on mechanical and/or chemical reactions, they don't work at the speed of light. I don't think your 170 micro seconds is far off.

[the_emperor]

2 minutes ago, JtD said:

This is how they manage the half meter. Real instantaneous fuzes will be a somewhat faster. But since the all are based on mechanical and/or chemical reactions, they don't work at the speed of light. I don't think your 170 micro seconds is far off.

That seems reasonable since both fuzes use "superqick" as terminology, and would result in  about 5-10cm of travel depending on the rounds velocity

[Barnacles]

I'm starting to think the 50 cal AP speed loss isn't too far off, but the HE rounds are over modelled and my initial thoughts were affected by the big disparity in game between HE and AP.
 

In game, if you deliberately rip your gear doors off, and fly with your bomb bay doors open, in the pe2 S.35 you lose about 30kmh from your top speed.

If you get hit by 1 x 151/20 HE you lose the same.

Now the bomb bay alone looks like around 3 square meters at least.

How big does the game think the holes made by HE rounds are?

Also a tempest goes 600kmh clean at 2000m at full power. Lowering the landing gear slows you to 463kmh. In my test 1 x 20mm HE to the tail slows you down to 474kmh, (This value doesn't vary wildly in game, so HE and gear lowered speed losses are almost the same)

Now I'm sure you can find an example of a plane damaged by 20mm he where the damage is going to without doubt cause speed loss, maybe so severe (panel loss) where it might be of the same order as lowering the landing gear, but there is no way that this should be the routine consequence of getting 1 x 20mm hit every single time (which I've pretty much found through testing)
 

I know it was an effective weapon. BUT every time I've tested it, HE 151/20 causes massive speed loss comparable to things like much bigger holes, or something obviously more significant.
 

Edited November 23, 2020 by Barnacles

[Barnacles]

This is a thirty millimetre hit. I'd say something like this should be causing that order of speed loss. Is it correct to say then that in game all 20mms are hitting like 30mm, in terms of aero damage at least?

 

[Cpt_Siddy]

1 hour ago, Barnacles said:

This is a thirty millimetre hit. I'd say something like this should be causing that order of speed loss. Is it correct to say then that in game all 20mms are hitting like 30mm, in terms of aero damage at least?

 

 

This hit is fatal. 

[Barnacles]

"probably fatal due to loss of control"

Doesn't really affect my point.

It's still going to impart an increase in frontal area/increase the coefficient of drag of the wing. It may well cause airframe loss of control due to loss of lift, but so might say lowering only one of your landing gears in certain flight regimes.

My point is, *you can argue* that because the area of the hole and the increase in frontal area is approx. the same as lowered landing gear/open doors,  the decrease in speed owing to extra drag should be of the same order ALL THINGS BEING EQUAL ie assuming you could control the plane, which you probably couldn't. Yes you rightly point out that's an assumption so thanks for that.

Edited November 23, 2020 by Barnacles

[unreasonable]

2 hours ago, Barnacles said:

I know it was an effective weapon. BUT every time I've tested it, HE 151/20 causes massive speed loss comparable to things like much bigger holes, or something obviously more significant.
 

 

I am sympathetic to this line of argument, you might be right,  but there are still a few theoretical problems with it. There are holes - and holes. What one thinks is "obvious" may not be true at all. 

 

While the drag penalty may be broadly proportional to the size of the affected area, +/- some allowance for roughness of the edges, the lift penalty, if any, is not. Holes of a given size on the upper surface of a wing, I believe I am right in saying, will create a much larger penalty than those on the lower surface. Holes not on a lifting surface will not create any significant lift penalty.

 

When a plane is trying to maintain a set altitude and power output, but suffers a lift penalty, it will have to increase AoA to stay level, thus increasing induced drag in addition to the surface drag caused by the hole itself.  Additionally, unlike the cases of bomb bay doors or gear coverings, damage is always almost inflicted asymmetrically, potentially creating significant yaw. 

 

  

[JV69badatflyski]

20 minutes ago, Barnacles said:

"probably fatal due to loss of control"

 

You took the wrong comment, the right one is:
30mm HE without tracer to Spitfire wing - "lethal"

https://imgur.com/gallery/HkGqW

But actually whatever comment you take from the above mentionned link, none of the spits serving as target survived the tests, and this was without any kind of aerodynamical-load on the airframes.
Until now, playing only offline, never saw a 20mm causing an immediate loss of control, but with the 30mm yes, even if the wing doesn't come off, most spits hit in the wings simply go into an unrecoverable spin.
KR
 

[Barnacles]

44 minutes ago, unreasonable said:

 

I am sympathetic to this line of argument, you might be right,  but there are still a few theoretical problems with it. There are holes - and holes. What one thinks is "obvious" may not be true at all. 

 

While the drag penalty may be broadly proportional to the size of the affected area, +/- some allowance for roughness of the edges, the lift penalty, if any, is not. Holes of a given size on the upper surface of a wing, I believe I am right in saying, will create a much larger penalty than those on the lower surface. Holes not on a lifting surface will not create any significant lift penalty.

 

When a plane is trying to maintain a set altitude and power output, but suffers a lift penalty, it will have to increase AoA to stay level, thus increasing induced drag in addition to the surface drag caused by the hole itself.  Additionally, unlike the cases of bomb bay doors or gear coverings, damage is always almost inflicted asymmetrically, potentially creating significant yaw. 

 

  

I fail to see, even if you make a maximum allowance for the things that you mentioned above ( jaggedness, asymmetric losses, depth of hole etc. )And err on the side of high loss, that you'd end up with justification for most 20mm hits causing the same speed  loss as lowering your landing gear. Just because I don't think the surface area etc is even close between the two. If they were of course a jagged, asymmetric hole would be way more draggy.I'd yield that you may be able to justify that worst case scenario damage might, but that's a stretch.

And even then, many of your points don't apply because my test was in the tail, so lift loss did not apply

 

But your points are nonetheless very valid, so thank you

Edited November 23, 2020 by Barnacles

[Barnacles]

1 hour ago, JV69badatflyski said:

You took the wrong comment, the right one is:
30mm HE without tracer to Spitfire wing - "lethal"

https://imgur.com/gallery/HkGqW

But actually whatever comment you take from the above mentionned link, none of the spits serving as target survived the tests, and this was without any kind of aerodynamical-load on the airframes.
Until now, playing only offline, never saw a 20mm causing an immediate loss of control, but with the 30mm yes, even if the wing doesn't come off, most spits hit in the wings simply go into an unrecoverable spin.
KR
 

I've gone into a spin from being hit by 13mm he in a p47 in game.

[JtD]

Yeah, gear down is pretty sh*tty aerodynamicwise, and while it might be possible to score a 20mm hit that has a similar effect, as a standard it shouldn't (on aluminium skinned aircraft).

 

Ballpark: If you were to assume a speed drop from 600 to 474 km/h CAS and a 1200kW engine (at prop), you'd have created about 4000N of extra drag. Dynamic pressure at 474 means that you'd need about half a square meter cross section minimum to create that kind of drag (you'd need to stop the air dead over that cross section). A wing with a thickness of say 0.3 meters would thus need a about 1.5 m damage spanwise in order to achieve this, which is about 5-10 times of what you typically get from 20mm HE.

[Barnacles]

3 minutes ago, JtD said:

Yeah, gear down is pretty sh*tty aerodynamicwise, and while it might be possible to score a 20mm hit that has a similar effect, as a standard it shouldn't (on aluminium skinned aircraft).

 

Ballpark: If you were to assume a speed drop from 600 to 474 km/h CAS and a 1200kW engine (at prop), you'd have created about 4000N of extra drag. Dynamic pressure at 474 means that you'd need about half a square meter cross section minimum to create that kind of drag (you'd need to stop the air dead over that cross section). A wing with a thickness of say 0.3 meters would thus need a about 1.5 m damage spanwise in order to achieve this, which is about 5-10 times of what you typically get from 20mm HE.

Thanks ever so much. I would add that my test wasn't an outlier. I only recorded one sample exactly but I did another few single hits  and they were all below 100kmh speed loss and around. 115 kmh for the tempest. 

 

I'd like to have a bigger sample though because I am genuinely surprised how little variation there is. 

[unreasonable]

15 minutes ago, Barnacles said:

Thanks ever so much. I would add that my test wasn't an outlier. I only recorded one sample exactly but I did another few single hits  and they were all below 100kmh speed loss and around. 115 kmh for the tempest. 

 

I'd like to have a bigger sample though because I am genuinely surprised how little variation there is. 

 

The lack of variation - assuming that you are usually getting a similarly sized  part of the plane - probably reflects that while the damage output from the shell may be RNGed, the drag from a damaged area is linked to it's graphic surface damage level, perhaps on a constant quantity per level. Your hit on a certain part might almost always trigger the same level of surface damage, if the range of damage from the shell is small compared to the bands of damage needed to trigger the levels.

 

Having said that, I would expect level 2 on a large wing hit box to create more penalty than level 2 on a smaller hit box.

[Barnacles]

3 hours ago, unreasonable said:

 

The lack of variation - assuming that you are usually getting a similarly sized  part of the plane - probably reflects that while the damage output from the shell may be RNGed, the drag from a damaged area is linked to it's graphic surface damage level, perhaps on a constant quantity per level. Your hit on a certain part might almost always trigger the same level of surface damage, if the range of damage from the shell is small compared to the bands of damage needed to trigger the levels.

 

Having said that, I would expect level 2 on a large wing hit box to create more penalty than level 2 on a smaller hit box.

That would explain a lot, but when they issued this DM they said to "ignore the visuals, as they weren't necessarily tied". IIRC

 

But TBF I'm totally with you on that theory until someone in the know confirms otherwise

 

[RedKestrel]

6 minutes ago, Barnacles said:

That would explain a lot, but when they issued this DM they said to "ignore the visuals, as they weren't necessarily tied". IIRC

 

But TBF I'm totally with you on that theory until someone in the know confirms otherwise

 

I think what they mean by that 'not really tied' thing is that if you see a bullet hole in a specific location, it doesn't mean that a bullet hit that exact spot. Sometimes people were saying "there's a hole in the plane here, that bullet should have hit the pilot' but it was just the position of the damage decal. But the degree of damage shown by the decal as an abstraction is pretty representative of the effect on speed and lift. 

[unreasonable]

That is what I thought was meant too - additionally that the damage graphics are generic to all shell types: small AP and large HE use the same selection of graphics per damage level. You cannot tell what type of ammunition caused the damage just by looking at it. 

 

[Caudron431]

On 11/20/2020 at 7:51 AM, -SF-Disarray said:

Except there are other things in the wing that can be hit that will affect the plane negatively other than the spar. First and foremost, the skin of the plane: If you disrupt the surface the increase in drag should cause a loss of speed. And if the round were to come in from any kind of angle other than perpendicular the disruption to the skin of the aircraft is going to be more than a half inch hole on either side of the wing. This isn't happening in an appreciable sense. Next you have control systems and those are not being damaged with any frequency in so far as I'm aware. In some planes you have pressurized tanks in the wing, the 109 has a nice oxygen tank nestled into the wing on the right side for example. Strike one of those with a round and you can get a nice explosive decompression that would cause all kinds of bother for a plane. Some planes have guns in the wing and the associated ammo box but neither the guns are being broken nor the ammo being detonated with any great frequency. The mechanisms for the flaps and landing gear extension are in the wings too but they never seem to break or jam up. Now, all of these things are bigger than wing spars, perhaps with the exception of control linkages, but we don't see them getting damaged. Instead we see planes regularly taking hits that should result in damages to these things, by virtue of volume of fire if nothing else, but persist in being combat effective. Curious that.

 

There are also those little and fragile devices called slats. On aircraft that have them like La5, MiG3, Bf109,  a damaged or destroyed slat would make  controlling aircraft under G very difficult or maybe even impossible in some instance. However i have never seen slats damaged in any other way than detaching/dissapearing when wing is already separated from the plane.

[-332FG-Buddy]

On 11/21/2020 at 2:44 AM, BCI-Nazgul said:

Because we all know that in real life American pilots had the  time and training to carefully aim at certain parts of the enemy all the time???  Do realize how ridiculous this statement is?  Or are you being sarcastic?

That's part of the problem.   They don't anything UNLESS there is a critical hit, so your opponent just keeps on fighting and killing you.  Meanwhile one hit from any HE round and you out of the fight including 13mm.  ONE HIT.   People are frustrated.  If the .50 hits actually did something to make the other plane less flyable on non-engine and pilot hits people would probably shut up.

Sure, if you have a nice stationary target that lets you fill it full of holes in one place.   That will NEVER happen online or in single while a plane is actually flying.   The precision required is impossible.  You'd have to be at exact convergence firing at completely non-maneuvering target.  I've never seen it in the entire time I've played this game.   The problem is that the damage model does not account for hits all over the plane to achieve the same effect as level 2 damage in one certain area.   My guess is that dozens of holes all over the plane would make it at least as hard to fly as 20 holes in one part of the wing like your picture shows.

I need to look into DCS.  Clearly they have the .50s figured out.  Maybe it's time for a switch.

Ive switched already, and in my opinion they have it figured out nicely.  There has been a issue with these 50s since April.  We have tried to bring it up but the conversation is muddied by people trying to say our complaint isn't valid.  The devs havnt responded, and don't know what their thoughts are, but I do know they keep closing threads.  

 

It's funny, as some one who has actually used a 50 cal in combat and seen it's effects, I wonder how much of these people commenting share that experience or get it of a website or youtube?.  Knowing what I KNOW, I IMAGINE 30-40 ROUNDS  to cause at least enough damage to affect the aerodynamics.

 

I loved this game spent money on it for myself and other people .......and I want it to be good and historic as much as possible, but it just doesn't seem it's going that way.  I'm not a 51 fanboy, I like the 190 and spitfire, 47, p40 and more.  So this isn't coming from fanboy mindset, it's coming from an enthusiast mindset.  

 

Unless the devs address this we are just speaking in circles and allowing people to continue to deflect the conversation, creating a convoluted thread ...the devs won't look at.  

 

O7

[-250H-Ursus_]

I will repeat myself over and over untill there is a change.

 

There is always the same 2 versions of M2 .50 cal problem.

 

"It kills my pilot everytime, the armor of german figher / bombers are wrong" (Most common in ppl which doesn't use allied fighters never, or only one time per month)

 

"I suffer for shot down a single target with .50s, if i don't pilot kill them"

 

 

And in my opinion, and based on my experience, the second version of the complaining is the correct. Since i think the problem is the lack of structural damage, aero penalty after severe hits like a burst and of course, the lack of incendiary ammo which should increase the .50 cal damage by a lot.

 

Also, there is a few problems which there seems related to the DM, like the visual damage doesn't reflects the structural damage, that is specially well noticed on 190s after get hitted by the 20. Or the most common now "SPARKS" no damage of big cannons like 30mm or 37mm, that wasn't hapening in the previous damage model.

 

Off course this makes me think that the DM is not fully developed yet, since the previous one, with their faults like the glass made P-47 and the flying Tank LaGG-3 were something, it seemed more finished and polished than this one.

 

I can't ask to much to. This year has been rough to think about replace the entire DM and polish it fast. So i think it will change sooner or later. And is not the first time since something was actually wrong and it was fixed in time, or added in time.

Edited December 10, 2020 by RoyalUrsus

[ACG_Cass]

Exactly. The problem isn't that they don't work at all. It's that the actual damage they do to the air frame seems incorrect. 

 

They are quite effective providing you kill the pilot or manage to set a fire. But the amount of rounds it takes to actual affect the handling or create a speed penalty to the aircraft appears to be way off. 

 

I selected a month (August 1943) and compiled a report of all the encounter reports on - http://www.wwiiaircraftperformance.org/p-47/p-47-encounter-reports.html.

 

I made some estimation on the rounds being fire. Sometimes it is the total rounds from the report divided by the number of aircraft, other times it is estimated from their reported burst time. These obviously don't necessarily correlate with hits, but thought it was useful information. 

 

 

This is just from a single month so the reports haven't been cherry picked to suit the argument. The conclusions you can reach from the language used is that the P47's 8 .50 Cals were pretty effective against fighters. They appear to be able to regularly cause - fires, smoke, severe controlability issues, structural issues, pieces falling off. 

 

I understand we do not have API implemented so the fire and explosion aspect will be reduced. But you would think pure AP would actually be more effective at structure and skin damage. 

 

But you can see below in the sim we get:

• very limited speed loss for a large number of rounds
• almost no pieces or skin coming off (understand the effects for this don't necessarily have to be there but we don't appear to get any speed loss from skin damage caused by pieces falling off and the decals remain in their first stage)
• structural damage only seems to come after an enormous amount of rounds (caveat to the is the 109s wing tips appear to be modeled almost too weakly and will come off after a very limited number of rounds - but who aims for the wing tips?)
• controlability doesn't seem to be an issue even after taking a huge number of rounds

You can see at the end of the video the comparative effectiveness of a single 20mm Hispano + 4 .50s. 

 

It's not a case of a single .50 not having an effect. It's the exponential damage to the structure and skin that would be expected of 10/20/30 hits to the air-frame that is missing. 

 

That is where the complaints come from. They are effective providing you hit one the modeled components in the right way, but outside of that they don't cause the damage that they should and allow an e/a to fight on without any penalty - that's the problem. 

 

 

 

 

 

[-250H-Ursus_]

On 12/13/2020 at 11:21 AM, Cass said:

Exactly. The problem isn't that they don't work at all. It's that the actual damage they do to the air frame seems incorrect. 

 

They are quite effective providing you kill the pilot or manage to set a fire. But the amount of rounds it takes to actual affect the handling or create a speed penalty to the aircraft appears to be way off. 

 

I selected a month (August 1943) and compiled a report of all the encounter reports on - http://www.wwiiaircraftperformance.org/p-47/p-47-encounter-reports.html.

 

I made some estimation on the rounds being fire. Sometimes it is the total rounds from the report divided by the number of aircraft, other times it is estimated from their reported burst time. These obviously don't necessarily correlate with hits, but thought it was useful information. 

 

 

This is just from a single month so the reports haven't been cherry picked to suit the argument. The conclusions you can reach from the language used is that the P47's 8 .50 Cals were pretty effective against fighters. They appear to be able to regularly cause - fires, smoke, severe controlability issues, structural issues, pieces falling off. 

 

I understand we do not have API implemented so the fire and explosion aspect will be reduced. But you would think pure AP would actually be more effective at structure and skin damage. 

 

But you can see below in the sim we get:

• very limited speed loss for a large number of rounds
• almost no pieces or skin coming off (understand the effects for this don't necessarily have to be there but we don't appear to get any speed loss from skin damage caused by pieces falling off and the decals remain in their first stage)
• structural damage only seems to come after an enormous amount of rounds (caveat to the is the 109s wing tips appear to be modeled almost too weakly and will come off after a very limited number of rounds - but who aims for the wing tips?)
• controlability doesn't seem to be an issue even after taking a huge number of rounds

You can see at the end of the video the comparative effectiveness of a single 20mm Hispano + 4 .50s. 

 

It's not a case of a single .50 not having an effect. It's the exponential damage to the structure and skin that would be expected of 10/20/30 hits to the air-frame that is missing. 

 

That is where the complaints come from. They are effective providing you hit one the modeled components in the right way, but outside of that they don't cause the damage that they should and allow an e/a to fight on without any penalty - that's the problem. 

 

 

 

Take in consideration, those reports are WITHOUT the API-APIT ammo belts which were more common in 1944 (M8-M20 bullets)

[357th_KW]

1 hour ago, RoyalUrsus said:

Take in consideration, those reports are WITHOUT the API-APIT ammo belts which were more common in 1944 (M8-M20 bullets)

 

The 4th FG reports from August '43 all mention API being used (presumably the M8 round).  The 56th FG from this period all mention AP & I (their later 1944 reports mention API) so they appear to have used a mix of M2 AP and M1 Incendiary.  Sadly none of the 78th FG reports for the entire war mention ammo expenditure or type.

[-250H-Ursus_]

9 hours ago, -332FG-KW_1979 said:

 

The 4th FG reports from August '43 all mention API being used (presumably the M8 round).  The 56th FG from this period all mention AP & I (their later 1944 reports mention API) so they appear to have used a mix of M2 AP and M1 Incendiary.  Sadly none of the 78th FG reports for the entire war mention ammo expenditure or type.

Could be the M8 Round, is earlier. But i read once than M8 with M20 were used later.

And some damage reports of M23 round even, but that is for 1945 only and very late war

[Creep]

speaks for itself. 

 

[Roland_HUNter]

On 12/21/2020 at 7:17 PM, QB.Creep said:

speaks for itself. 

 

You guys wanted stronger .50 cal?

At the end the Fw-190 took, looks like  300-400 hit in himself. You can see he sustained the same damage as it would be in the game.
Lots of hole  on it and engine on fire.

[-SF-Disarray]

300-400 hits? That looked like 20 or so hits to me. It is kind of funny that one piece of grainy film and your 'estimation' of the number of hits is enough evidence that everything is fine for you when all the other evidence pointing out the problem isn't.

[JtD]

US guncam evaluation gives an average of 6.7s firing time for a 8 gun P-47 from footage where a kill against German opposition was recorded.

 

Say 100 rounds per gun, 8 guns, 800 rounds spend. Say 3% hit ratio, which would be excellent*, you're at 24 hits per kill average.

 

*Evaluated gun cam from German fighters gives about 1 noticeable hit for 200 rounds fired. Incendiary and HE would mostly qualify as noticeable, while AP would not. Small caliber would also be harder to notice than larger caliber. If you were to disregard anything smaller than 20mm for this reason, you'd be at aout 1 hit out of 100 rounds fired, if you were to assume that only one out of three rounds created a visible hit, you'd be at about 3 hits out of 100 rounds fired. So 3% hits is pretty much the upper end of what can be assumed as a typical average, while 0.5% is the lower end.

[Roland_HUNter]

7 hours ago, -SF-Disarray said:

300-400 hits? That looked like 20 or so hits to me. It is kind of funny that one piece of grainy film and your 'estimation' of the number of hits is enough evidence that everything is fine for you when all the other evidence pointing out the problem isn't.

I counted 41. And its only the API-T(white flashes) hits. You cant see the AP-I Hits.
If u see how much those flashes are scattered u can imagine easily: he not used small bursts to shot down that 190.

[-SF-Disarray]

The flashes are incendiary rounds detonating, be they rounds fitted with a tracer bead of not; I guess you could say the flash is the ignition of the incendiary compound if you like that better. The tracer compound is the light coming off the back of the round. It is ignited when the round is fired, not when it impacts. In that clip of frame by frame footage there might be some tracers to be seen, but it is hard to tell what is a tracer and what are artifacts from the old, poor quality film.

 

At any rate the number of rounds that hit that target are far lower than the 400 you had said originally. If that many rounds were to have hit the target where those impacts were shown to have hit, I'd expect rather more catastrophic damage. 40 impacts seems more realistic but would still be a statistical outlier; it was estimated, by the Army during the war, that it took between 15 and 25 .50 rounds to bring down a fighter on average. And I'm still standing by my count of around 20 impacts. Being very generous on what can be considered an impact, I'd say the plane was already on fire by the time the 15th round hits. Further, this is one, isolated, example and doesn't really prove anything. Going even further, this has little bearing on how the guns are performing in the game.

Edited December 27, 2020 by -SF-Disarray

[357th_KW]

Just for some reference, a squad mate of mine pulled a bunch of multiplayer stats data for me and the .50s are currently taking at least 60 or so hits on average to produce a kill right now (I say at least, as there was no practical way to filter out cases where other calibers or flak had damaged the plane that eventually went down).  I'm trying to get some more refined data that filters for target type, and also includes stats from the Spit and Tempest to get a better breakdown of how the compare to the Hispano 20mm in game.  Hopefully I'll have some more concrete data in the future.

[Hawk-2a]

13 minutes ago, -332FG-KW_1979 said:

Just for some reference, a squad mate of mine pulled a bunch of multiplayer stats data for me and the .50s are currently taking at least 60 or so hits on average to produce a kill right now

As far as i remember, this thread is not about how much it takes to kill a plane, but rather on how much drag .50 cal hits add when hit by them...

[Roland_HUNter]

11 hours ago, -SF-Disarray said:

The flashes are incendiary rounds detonating, be they rounds fitted with a tracer bead of not; I guess you could say the flash is the ignition of the incendiary compound if you like that better. The tracer compound is the light coming off the back of the round. It is ignited when the round is fired, not when it impacts. In that clip of frame by frame footage there might be some tracers to be seen, but it is hard to tell what is a tracer and what are artifacts from the old, poor quality film.

 

At any rate the number of rounds that hit that target are far lower than the 400 you had said originally. If that many rounds were to have hit the target where those impacts were shown to have hit, I'd expect rather more catastrophic damage. 40 impacts seems more realistic but would still be a statistical outlier; it was estimated, by the Army during the war, that it took between 15 and 25 .50 rounds to bring down a fighter on average. And I'm still standing by my count of around 20 impacts. Being very generous on what can be considered an impact, I'd say the plane was already on fire by the time the 15th round hits. Further, this is one, isolated, example and doesn't really prove anything. Going even further, this has little bearing on how the guns are performing in the game.

[357th_KW]

22 minutes ago, -[HRAF]Roland_HUNter said:

Based on those calculations, 10 hits of .50 API-T from 12 o’clock low on the P-47 has roughly a 17% chance of producing an “A kill” (what we’d consider a kill).  So about 30 hits gets you around 50%.  So just a bit higher than what @-SF-Disarray mentioned, but against a P-47 rather than a 109 or 190.  Both data points seem to correlate.

[HandyNasty]

Correct me if I am wrong but in the document, the line of fire unto the P-47 is "Front and Below". So idk about comparing it with shooting down a plane from "above and behind" like the video of the 190 getting shot down.

[unreasonable]

Just now, =FSB=HandyNasty said:

Correct me if I am wrong but in the document, the line of fire unto the P-47 is "Front and Below". So idk about comparing it with shooting down a plane from "above and behind" like the video of the 190 getting shot down.

 

You are not wrong - and of course it is a different model of aircraft -  but you can still use the data to ball park the probability of kills from other angles: at least it is better than guessed rules of thumb.  The report's overall probability is worked out from the probability of a kill from a hit on a component area (pilot, fuel tanks, engine, structure), multiplied by the percentage of the overall area presented by each component from that particular angle, taking into account any specific armour protection. So if you took the P-47 numbers for the p of a kill when a type of area is hit and re-weighted them for the relevant areas in a different radial engine plane at another angle you would have a reasonable estimate.

 

For instance, as the report states, for the angle of fire in the P-47 tests the pilot is not well protected. Firing from an angle where the engine is not much in view and the pilot is well protected could generate probabilities per kill for engine and pilot considerably lower than in the report case, which models ground fire or bomber defensive fire. On the other hand you might get more damage to the super/turbocharger - which I suspect would be more likely to create B kills, but an engineer would know better. 

 

A recalculated probability will not necessarily be exactly what the experimenters would have found if they had run real tests, but given the range of the confidence limits it would be a good place to start. 

 

Just now, -332FG-KW_1979 said:

Based on those calculations, 10 hits of .50 API-T from 12 o’clock low on the P-47 has roughly a 17% chance of producing an “A kill” (what we’d consider a kill).  So about 30 hits gets you around 50%.  So just a bit higher than what @-SF-Disarray mentioned, but against a P-47 rather than a 109 or 190.  Both data points seem to correlate.

 

You should not just add probabilities like that.

 

A kill p = 0.017, the report assumes independence.   That means after 10 hits, you have p= 0.983^10 of not being an A kill = 0.842     so p 0.158 of being A killed at some point in ten hits. (Say 16%)

 

After 30 hits you have p = 0.983^30 of not being an A kill = 0.598 so 0.402 of being an A kill at some point in thirty hits. (Say 40%)  To get to 50% you need 40 hits.

 

Not wildly different from your answers, but better to do it the right way.  Also note that most planes are shot down with a number of hits lower than the mean average. The distribution of frequency and number of hits is not a normal distribution, but will have a long tail: ie those lucky planes that take a lot of hits before going down will skew the mean upwards.  So 40 hits A kills half of the planes: it is not the mean number, which would be higher. 

 

For a genuinely independent p of A kill of 0.017 the mean number of hits = 1/0.017 = 58.8  

 

 

 

 

[Creep]

On 12/26/2020 at 11:50 AM, -[HRAF]Roland_HUNter said:

You guys wanted stronger .50 cal?

Am I to understand that you believe the US .50 rounds in-game are modeled correctly relative to the MG131?

[Roland_HUNter]

13 minutes ago, QB.Creep said:

Am I to understand that you believe the US .50 rounds in-game are modeled correctly relative to the MG131?

MG-131 has HEI shells, 50 cal has not. HEI shell ll damage the plane surface more. Its cannot be equal.

[ACG_Cass]

@unreasonable
thank you for finally explaining the mathematics behind those! Being trying to wrap my head around it for a while now.

 

I'd like to the "C" damage chart as well. I think the overall average rounds to fully kill  a plane with .50 cal probably isn't that far off in game. We see some very quick kills providing the right components are hit and there are outliers where a lot more rounds are needed.

 

The issue, and the reason for this thread, is that the .50s don't appear to do enough of the "B" and "C" damage categories and the exponential aerodynamic and structural damage you'd see from hitting the aircraft with 20/30+ rounds doesn't appear to be modelled properly. It's the fact that until you hit something, the target can fly unimpeded in a situation where it should be quite badly damaged.

 

@-[HRAF]Roland_HUNter

They shouldn't be equal no. But the difference between a 13mm HEI round and a 12.7mm AP round is not as pronounced as it is in the game. The HEI component isn't big enough to create the skin damage associated with 20mm+ and is largely there for it's incendiary proposes.