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Also considering only a single diameter sized hole for AP projectiles would be the most pesimistic scenario. Since you would often have exit holes that would be usually larger than the entrance holes. Also you would have to consider the angle of projectile impact. It's not the same having a round going perpendicular into a flight control surface than working it's way in from a very angled aspect, like it happens from 6 o clock hits. You can also have projectile deformation and tumbling depending on what internal elements are impacted inside, which would also lead to bigger and messier exit holes.


 

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Testing tracks for the .50 cal 

 

Here are are a short series of tracks with P-47 AI firing at a G-14. It doesn't show the tech tips and info in the video but almost immediately that the G-14 is hit systems internal damage is taking place. For those interested the tracks are here :-    https://drive.google.com/file/d/1Lmjni-7SQvbFPUxydwM0upRXVKT0iRSv/view?usp=sharing

 

You are free to make your own minds up from the videos posted here.

 

 

 

 

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5 minutes ago, sniperton said:

For a better understanding of the problem please read it thorougly:

I understand perfectly well. Unfortunately this complaint has been spread across so many sections of the forum that it's ranged from the .50 cals are utterly useless and completely ineffective to the .50 cal AP have absolutely no determinable effect on aerodynamics/drag.

 

People are free to download the tracks above and come to their own conclusions.     

 

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For starters, thank you @Han and @=FB=VikS for getting back to me. This kind of dialogue is exactly what myself and dozens of other community members have been asking for. Through this we can come to a collective conclusion on what the DM should be. There's a lot to break down, and a lot of evidence to supply, so I'll try to keep it organized.

 

Response to Initial Claims

 

For starters, the photographic evidence you provided to make your point is misleading. The top picture is of a 20mm shell, as has been confirmed by @ZachariasX, and the bottom image a DO-17 receiving .303 fire in 1940. Neither of these pictures are representative of the caliber we are discussing. As such, they contribute little to the discussion.

 

Secondly, you state that "API rounds are very effective to...", but I would like to clarify that within IL2 only AP ammunition is modeled. I'm just making sure we are on the same page.

 

VikS, the video you provided was very interesting, but it should be noted that this is not a good comparative test, as for the HEI rounds, the barrels were empty, while the API was fired against barrels filled with water. Also, the impact angle was at 90 degrees, providing the bullet with the smoothest path for entry, resulting in smooth entrance holes. It should also be noted that the exit hole of the API was far more significant than the HEI round, as shown in the below screenshot.

 image.png.11ada9dbea40ac1b926c96939906ee3c.png

You can see in the following screenshot that the HEI only let small fragmented bits through the back barrel, as the HE component was expended on the skin. 

image.png.f694028fb5d97cdd4778b5fe629f08ed.png

 

 

New Claims

From this point on in the post, I will be providing further evidence as to why the AP HMG rounds are currently under-modeled, and why the HE HMG rounds are over-modeled. Each section of evidence will be denoted with a header for ease of reading.

 

Tumbling and Drug Planes

Probably one of the best documented incidents of an aircraft receiving fire from the rear aspect through it's wing, is a drug bird in Brazil that was forced down by an FAB A-29

An article covering the matter is linked here: https://www.cavok.com.br/policia-civil-apreende-suposto-aviao-interceptado-e-alvejado-pela-fab-no-ultimo-sabado-um-setanejo-prefixo-pt-exp

 

The aircraft that was shot was a Piper Cherokee, an aircraft of comparable size to the BF-109.

Below is an image of the Cherokee's damage from 5 bullets of 12.7x99 API-T, which is standard use by the FAB's A-29 fleet. This image is overlaid and scaled to a Bf-109G14's wing in IL2, that has sustained 'Level 2' damage. Note that this damage level is impossible to achieve with M2's, as they will experience structural failure before showing any appreciable drag penalty. Further note that it only takes 1-2x MG131 or UB HE hits to achieve this level of damage.

image.png.b82456cdf823b22840d9ffcd78eb73fd.png

Once again, this damage level was caused by Five bullets. Not 83, which is what we found the average amount in IL2 to cause this damage level with M2 .50's. 

 

It should be noted that this type of tumbling is caused when the AP bullet strikes internal supporting structure, and will thus exit the wing of the aircraft at an off angle, possibly fragmenting as well. The internal structure of a Bf-109 is more resilient than the General Aviation Piper Cherokee, and thus, will have stronger and more plentiful internal structure to result in even more tumbling and fragmentation than shown in the Cherokees wing. 

 

https://www.sto.nato.int/publications/AGARD/AGARD-AG-238/AGARD-AG-238.pdf  The following NATO ballistic model further supports the idea that AP ammunition does the majority of its damage due to tumbling, and in its exit wound.

 

Note that the entrance angle is critical for this, and the current modeling of AP is a reasonable assumption to make if the shot is being made from a top down angle, where there is little supporting structure for the round to tumble on. 

 

This runs contrary to the statement that Han made: "13mm AP rounds makes makes 13mm holes in skin, or may be 13x25mm holes in case of shallow angle hit."

The hits in the above image look larger than 13x25mm

 

1.5g of PETN and a 300mm Hole?

Han also made the following statement: "13mm HE round may do a hole up to 300mm in diameter approx."

Both myself and many community members find this claim to be dubious. 

 

The following picture displays a German test displaying a strike from both a 30mm, and 20mm Mineshell round. 

unknown.png

 

The right hole is from the 20mm shell, and the diameter of which is roughly calculated to be 350mm.

A German MG131 HE tipped round contains a mere 8.3% of the explosive found in a 20mm Mineshell. 

The claim that a round using less than 1/10th the explosive of a larger cannon shell, can yield a hole that is 85% the size of a 20mm strike, is very, very questionable. 

 

A Distinct Lack of Structural Damage

The video that VikS provided on the HEI and API bullets, yielded a very interesting point. As shown in the picture above, the exit wound of the HEI round was a cluster of small splinters, as all of the rounds energy was expended on the surface of the barrel. Meanwhile, the exit wound of the API round, was a larger, more comprehensive gash, indicating that the round retained most of its structure, and retained more energy when traveling through the target, as only a small fraction of it was spent entering the barrel.

 

By referring to the bug report, you can find that both the UB and MG131 machine guns are 25% more effective at causing structural damage when compared to the Browning M2. 

 

This is in spite of the fact that 2/3rds of the bullets they fire should be HE tipped (1/3rds for the Russian UB's), and thus will have minimal effect on the supporting structure of the aircraft as the majority of its energy would be spend on the skin of the aircraft. Meanwhile, the AP rounds would retain more energy, and thus have more to translate to the main spar/supporting structure of the wing, and even if 100% energy transfer is not achieved, the remnants of the round that penetrated, would have a fragmentation pattern of gashing wounds as they exited. You can see this demonstrated in the first picture of the Piper Cherokee I posted. 

 

Possible Parallels in Ratios

As stated before, the following claims were made: 

“13mm AP rounds makes makes 13mm holes in skin, or may be 13x25mm holes in case of shallow angle hit.

13mm HE round may do a hole up to 300mm in diameter approx."

Through testing that was performed for the earlier bug report, we found that on average, AP ammunition is 2,352% less effective than German and Russian HE tipped HMG's at creating aerodynamic damage.

 

It seems that 300mm, the hole size that Han stated was possible for an HE tipped 13mm round to make, is exactly 2,350% larger than 12.7mm, the hole size that 12.7mm AP ammunition was claimed to make. The DM seems that the best and worse case scenarios for each ammunition type and stack them head to head.

 

Once again, it seems that only the entry damage is being calculated for  the bullets, with AP ammunition has been proven through both the picture of the drug plane and the video that VikS provided to do most of its damage when exiting its target. I will happily be corrected on this fact if I am wrong. 

 

Conflict with Reality

There are dozens upon dozens of accurate and verified AAR's of aircraft predominantly armed with M2 .50's that can be found at http://www.wwiiaircraftperformance.org. These reports consistently make note that a large volume of .50 AP/API rounds is easily capable of shredding off bits of the aircraft skin. The damage compounds very quickly as gashes in the skin rapidly link up to create larger holes. This phenomenon can be observed in the video VikS shared, as the barrels turn into a mangled mess after a burst of fire.

 

In Closing

I'd once again like to express my thanks for the devs opening up a dialogue on the matter, and I sincerely hope you consider the claims and evidence I've laid out in this post. This post is not made to badmouth the simulation. Myself and everyone who has offered invaluable help in gathering this evidence are exerting all of this energy because we genuinely love the experience it offers, and want to see it continue to improve in it's accuracy.  

 

Credit: I just quickly want to thank all the wonderful folks in the CB community who helped me compile all of this evidence. Special thanks to @Barnacles @Cass and @Bad_Aim for offering critical bits of information. 

 

Edited by QB.Shallot
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Awesome posts guys, 

 

Out of respect for the Devs and those providing such great information,

 

I'm going have a seat in the corner and let those with the knowledge discuss and hopefully have a good dialogue with one another. (Hopefully, because I know they are busy people)

 

I kindly suggest those coming from the emotional, or the, "that's not fair" stand point do the same. 

 

Cheers guys.

Again some top notch pictures and information. Thanks for all the effort on both sides.

Edited by Denum
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On 2/17/2021 at 6:19 PM, 6./ZG26_Custard said:

Testing tracks for the .50 cal 

 

Here are are a short series of tracks with P-47 AI firing at a G-14. It doesn't show the tech tips and info in the video but almost immediately that the G-14 is hit systems internal damage is taking place. For those interested the tracks are here :-    https://drive.google.com/file/d/1Lmjni-7SQvbFPUxydwM0upRXVKT0iRSv/view?usp=sharing

 

You are free to make your own minds up from the videos posted here.

 

 

 

 

Based on these tracks, I decided to do some more testing which showed the p-47 is the worst offender on the .50 cal equipped planes and one of the most apt to explode due to cannon rounds which is odd considering there are stories of German pilots emptying their ammo belts into p-47s and the pilots still made it back to base. I do also think putrid AI gunnery is at work here to an extent, mixed with a lack of extensive systems modeling (control cables), fuel systems modeling, and the lack of API rounds. But this result is confounding in a 2021 combat flight sim.

 

 

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There have been  numerous posts   basically claiming that API  is going to be the holy grail  for the .50 cal  guns and  somehow  make it the equal of the HE filled rounds the russians and germans used.  My understanding is that  API can be good at igniting fuel,  and leaves a nice puff of smoke  letting a pilot know  if  and where his strikes were.  It's not really explosive,  it's a hot burn.  It seemed to do wonders vs the light,  non sealing fuel tank,  japanese ac in the pacific.  Since the US was more heavily involved there well before africa and europe ,facing  european, mainly german and italian aircraft,  the view on effectiveness  of the .50 cal was tainted when compared to european ac.  They didn't increase the caliber to 20mm,  like all of the other combatants in europe,  who realized .50 cal was not up to the job,  even the he filled rounds that they fielded, and in a totally different class,a magnitude more effective than API, and they upgunned there ac with larger cannons. For the german 20 and 30mm guns, they were able to find a way to put more HE in the mine rounds than any of the enemies they faced so they had more damage capability.  API could be marginally better than AP,  but will still be nowhere near as effective as what the germans and russians were using.

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21 minutes ago, JG1_Wittmann said:

There have been  numerous posts   basically claiming that API  is going to be the holy grail  for the .50 cal  guns and  somehow  make it the equal of the HE filled rounds the russians and germans used.  My understanding is that  API can be good at igniting fuel,  and leaves a nice puff of smoke  letting a pilot know  if  and where his strikes were.  It's not really explosive,  it's a hot burn.  It seemed to do wonders vs the light,  non sealing fuel tank,  japanese ac in the pacific.  Since the US was more heavily involved there well before africa and europe ,facing  european, mainly german and italian aircraft,  the view on effectiveness  of the .50 cal was tainted when compared to european ac.  They didn't increase the caliber to 20mm,  like all of the other combatants in europe,  who realized .50 cal was not up to the job,  even the he filled rounds that they fielded, and in a totally different class,a magnitude more effective than API, and they upgunned there ac with larger cannons. For the german 20 and 30mm guns, they were able to find a way to put more HE in the mine rounds than any of the enemies they faced so they had more damage capability.  API could be marginally better than AP,  but will still be nowhere near as effective as what the germans and russians were using.

 

I agree that a .50 round is never going to be more powerful than HE 20mm which has a high likelihood of being a 1-short burst, 1-kill round for Axis and Hispanos   and less-so for Russian models.  (Am I correct in saying that's somewhat historical?)

What I disagree with is the currently modelled ineffectiveness of .50 when sheer volume of fire (convergence or not) comes into play. 

 

It's the difference between "death by a thousand cuts" over time vs. said "thousand cuts" happening all at once.  

I have little doubt that .50s sent alot of enemy planes home to be permanently decommissioned after their final landing and that result is likely closely comparative to outright kills but, I also do believe that a good, solid snap-shot should be enough to kill instantly.  When the chance to "park" on the enemy and blast away is happening, it should be highly fatal.  Accuracy for critical systems should be less of a concern because, let's face it, as long as you're hitting, you're most likely hitting everything.  

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I agree  with  the  amount of strikes, death by a thousand cuts,  analogy.  I think the problem  the community has  is how can that be tested ?  Does the ability exist  to add up every single round  that strikes an AC,  not  just  what you fired, but  actual hits ? Does the server logs show an entry for each individual round striking a target ?  How does it calculate if a second round enters the same hole,  maybe not perfectly bullseye but close ?   Those are the things that need to be known with  100%  accuracy  before any kind of actual damage test can be  close.

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7 hours ago, 69th_Mobile_BBQ said:

What I disagree with is the currently modelled ineffectiveness of .50 when sheer volume of fire (convergence or not) comes into play. 

I‘d say that there is only one case where this supposed „ineffectiveness“ really comes into play. This is shooting from straight 6, where they behave more like the .303 rounds. Else, it is generally easy to zap any other aircraft with them, SP or MP. That 13 mm HE are *very* effective currently in this game in dishing out hurt is another factor that raises the perception of the BMG rounds being „ineffecive“.

 

The problem here is that those long range shots from straight 6 are one of the principal strategies for us gamers. Normally, one strike and the other guy loses enough speed that you can creep up to him and finish him, as taking HE hits also gives him (usually) a siginficant disadvantage in the ensuing fight.

 

I don‘t think this is a simple issue to „fix“ in the current DM setting without having significant side effects. This should be looked at carefully.

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14 hours ago, ZachariasX said:

I‘d say that there is only one case where this supposed „ineffectiveness“ really comes into play. This is shooting from straight 6, where they behave more like the .303 rounds. Else, it is generally easy to zap any other aircraft with them, SP or MP. That 13 mm HE are *very* effective currently in this game in dishing out hurt is another factor that raises the perception of the BMG rounds being „ineffecive“.

 

The problem here is that those long range shots from straight 6 are one of the principal strategies for us gamers. Normally, one strike and the other guy loses enough speed that you can creep up to him and finish him, as taking HE hits also gives him (usually) a siginficant disadvantage in the ensuing fight.

 

I don‘t think this is a simple issue to „fix“ in the current DM setting without having significant side effects. This should be looked at carefully.

 

I'm not sure what game you're playing but, I've NEVER seen anything Axis lose speed or maneuverability from being hit.  

It's quite the opposite for the Allied planes which can't out-turn, out-climb, out-accelerate, out-decelerate, out-dive, out-top speed, out-stall speed or out gun ANYTHING Axis (including 88s and 111s).  Allied planes take ANYTHING greater than a few MG hits in the side of the fuselage as a reason to lose 75kph and/or disintegrate. 

If you get hit by anything casually sprayed in your general direction flying Allied planes, you might as well just bail out. 

Meanwhile, Axis flies perfectly fine when hit.  Hell. 109s don't even show a reaction when a wheel falls out of the wheel well.  110s, have ZERO penalty when flying with half the horizontal stab blown off.  They can continue pulling max Gs on half an elevator with ZERO need to compensate for any extra roll incidence or over loading this would cause.  

He-111s can even tank rocket hits directly to the tail, putting the damage graphic at max-level (all controls stripped of surface) and they can still turn and burn with the best of 'em.

 

I'm not sure what "significant side effects" you're trying to avoid.  As far as I'm concerned, if those "side effects" result in a FM and DM that's finally not BROKEN, I'll take it.  

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With regard to API and whether it would really improve .50 caliber performance in game, we don't have to guess.  There's real life test data on those rounds, and I did some extensive testing of the .50s in game and their ability to light fires back in 4.006 right after the new damage model dropped.

 

Testing of M1 Incendiary and M8 Armor Piercing Incendiary against German style tanks showed an average of around 1.5 hits to cause a fire.  Against the G14 and K4 in game I got averages of 58.4/79.3 & 49.8/78.7 hits to ignition from the side/rear.  Against the A8 and D9 it was 49.9/24.9 and 102.3/41.8 hits to ignition.  Those averages were from 10 passes at each aspect, fired statically using the A-20 gunner against a parked and running target.  It was clear that the rounds were hitting the fuel tanks and causing a leak right from the first burst.

 

In a different test using M20 API-T against American tanks in P-38s and B-25s (which had a different construction compared to the German tanks) showed far fewer one hit fires - around 10%.  But it showed that followup hits on a damaged tank had a 66% chance to start a fire.  Testing with just a rear shot on the wing tanks of these in game I got averages of 32.4 for the P-38 and 39.3 for the B-25.

 

So compared to real life results, ours in game are FAR worse.  An incendiary round that could actually start a fire with a handful of fuel tank hits, as real life tests indicate was likely, would be a HUGE upgrade to the vanilla AP we have in game right now.

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I can not seem to get my FW190 or variant AC  that are said to have 1.65 ATA of boost available  anywhere close to 1.65.  In winter it is closer.    Why it would be higher, but not 1.65 in the colder temps, I am not sure, as the supercharger was capable, as all are, of producing higher boost than regulated for.   1.54 1.55 is all I can achieve  on a summer map.   With the attention to detail taken by the developers I  find it difficult to believe that this inability to achieve the published level of boost is modeling error  ( is it ? )   so I have to assume that I am doing something wrong with my controls  in game that is restricting me from the proper pressure.

Please assist  in any way possible

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FC Vol1

 

Losing control cables is totally fine and next step in more adavanced damage simulation. But current FC implementation is IMHO wrong and unrealistic. Control surface can be jammed by push rods which they were not existant on most ww1 aeroplanes! This has other consequence - one side jammed  aileron will block other side, elevator was slipt into two and had redundant wires for both sides but in game elevator push rod will jamm whole surface at once in fixed possition when damaged. All this is fatal to the plane  and many time to the pilot, when during hit your control surface was deflected, becouse you can't compensate with working half surface. Lost (broken cable or control horn)  control surface or half of it should flutter freely on the air and you should fly by compensating and most plane had double redundant cables or 4 ailerons like Camel which is not implmented in the game.

 

 

VDp7slk.jpg

 

 

QAiWAwr.jpg

 

 

In the same spirit ,visual damage (no cables present) but whole control surface is operational.

 

 

 

Edited by 1PL-Husar-1Esk
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2 hours ago, -DED-Rapidus said:

@1PL-Husar-1Esk, so what's the question?

You need two hits for certain planes to snap two redundant control cables in order to lose control. This makes it almost impossible for random hits to eliminate control. In the game, it is a very likely occurrence. It is also not likely that the control surfaces can get stuck in a deflected position.

 

How that translates into the current DM and your application of the RNG is a different question though.

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3 hours ago, -DED-Rapidus said:

@1PL-Husar-1Esk, so what's the question?

Hi. This is mine and many others opinion (feedback from users @ forum) about current bad implementation of control surface damage model. Question is do devs team  gonna check it  and fix it if you decided that We as community are right in that subject?

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On 3/1/2021 at 8:48 PM, JG1_Wittmann said:

I can not seem to get my FW190 or variant AC  that are said to have 1.65 ATA of boost available  anywhere close to 1.65.  In winter it is closer.    Why it would be higher, but not 1.65 in the colder temps, I am not sure, as the supercharger was capable, as all are, of producing higher boost than regulated for.   1.54 1.55 is all I can achieve  on a summer map.   With the attention to detail taken by the developers I  find it difficult to believe that this inability to achieve the published level of boost is modeling error  ( is it ? )   so I have to assume that I am doing something wrong with my controls  in game that is restricting me from the proper pressure.

Please assist  in any way possible

Climb to 3km. By then the supercharger should shift into gear 2 and you'll be able to to pull 1.65ata. (the mp limit is lower in gear 1)

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8 hours ago, Barnacles said:

Climb to 3km. By then the supercharger should shift into gear 2 and you'll be able to to pull 1.65ata. (the mp limit is lower in gear 1)

Someone on the A6 thread has kindly posted a link with some test docs.  1.61 to 1.68   was  done in emergency use for the jabo FW's  in colder temps.  Not as cold as russian winter temps, but say  hovering around, slightly above or below freezing.  So,  the second speed is not necessary from the compressor  at 100m  altitude

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Could we look at updating the dispersion levels for planes that rely on wing mounted guns?

 

I created the below mod by slightly changing 1 value in the M2 weapons txt file and it had a significant impact on the weapons effectiveness. I tested all other M2 weapons including the Sherman, A20 rear gunner and the M2 AAA emplacements. There seems to be no detrimental effect to slightly increasing this. 

The data that is being used appears to be incorrect for the BoBp planes. The reference in Air Forces Manual No. 64 states that the expected accuracy for a Cal .50 fighter machine gun should be about 4 mils for 75% of the rounds, in game it is 4 mils for 100% of the rounds (below is a picture of the 4 mil pattern of a P47 out to 610m (2000ft).

 

withoutmod.PNG.cbccc18cfa8aee2cd800b07d22c799d8.PNG

 

This means every gun is pointed at exactly the same pixel even out to 2000ft, which is far fetched for what even the most experience crew chief would be wanting to do. 

 

The mod adds roughly 25% on top of this and you get a 5 mil spread out at 2000ft. A small change but it has a big impact in deflection shots and shooting from dead 6. It also means the comparatively high levels of accuracy required for gun platforms that were designed not to need it is reduced. 

 

withmod.PNG.e1031612a01ba02d1e1578d1a8a822c5.PNG

 

(these were measured with a ruler on the screen)

 

Dispersion post for reference:

 

Understand you guys are flat out trying to sort out the new update but for such a quick, simple change, this has an incredible impact on the multi-wing gun .50 Cal planes effectiveness without having to modify any of the damage model values. My method probably sits outside of what you would do internally as I can see that value is 0.0 across almost all the guns. But I assume there is another value that can be changed and this easily it would be such an easy win

 

 

Additional:

So after re-looking at the plane files it appears as though each plane has the below value:

 

P47
image.png.e8217e5559249f007ea79fddc735287b.png

 

P51

image.png.8db1d6c3b38cc115f6214b910e4448a0.png

 

(all appear to have the same value)

 

Unfortunately we don't appear to be able to edit the plane files without the game crashing, but wondering if this is something that can be updated?

 

Here is the harmonization chart for the P47. 

 

330731812_P47chart.PNG.bf6ccf0dfeaaf11ce4b3452e7c5f018c.PNG

 

Below are the 8ft squares out to our range tested in game. The difference being that only 75% of rounds were expected to hit within those holes, not the 100% we currently have implemented. 

 

p47chart2.PNG.ae726723390209ca2add182afb74ad7a.PNG

 

 

sidenote: more than happy to do any additional testing if needed

 

 

Edited by ACG_Cass
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Someone has kindly pointed out that there is a a direct example of a typical dispersion cone for the M2 AP ammunition, please see below. 

 

p67.thumb.PNG.09a2563570161436badd88feb97d9350.PNG

 

This means that in terms of total dispersion the current implementation is roughly 50% of what it should be historically in the BoBp planes. Completely understand as we can see from the notes in the code that this was either taken from a direct test with a P40 or an earlier piece of documentation and has been applied to all other M2 equipped guns, so no fault from a development perspective. 

 

Without understanding the way the ballistics model calculates dispersion levels based off the values inputted I would hazard that 8 mils might be too much, especially with the the increase based on barrel temperature, but at least a 25% increase to ~6 mils would still have a very significant impact and bring them very close to historically accuracy.

 

I also understand that my current implementation isn't ideal as it closes the gap between the minimum and maximum dispersion levels. The means that although the dispersion increases at the same rate with temperature rise, the increased starting value means it increases quicker. 

 

Sorry to keep bringing this up but with the completely understandable difficulties your facing trying to create a damage model that spans 2 era's of air combat and a tank module, something that can so easily be updated and so significantly increase the effectiveness of one of the most affected weapon platforms is a very unique opportunity. I've tested a further small additional increase on top of my mod and the difference between the 6 and 8 gun platforms in even more significant. Something that isn't very pronounced with the current dispersion. 

 

Again, more than happy to field any questions on PM or here and do any additional testing of values if needed. I know your workload at the moment with the new update must be very significant. 

 

Thanks, 

Cass

 

Also credit to @VBF-12_KW
for actually finding the page.

Edited by ACG_Cass
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On 4/5/2021 at 11:09 AM, ACG_Cass said:

Could we look at updating the dispersion levels for planes that rely on wing mounted guns?

 

I created the below mod by slightly changing 1 value in the M2 weapons txt file and it had a significant impact on the weapons effectiveness. I tested all other M2 weapons including the Sherman, A20 rear gunner and the M2 AAA emplacements. There seems to be no detrimental effect to slightly increasing this. 

 

withmod.PNG.e1031612a01ba02d1e1578d1a8a822c5.PNG

 

(these were measured with a ruler on the screen)

 

Additional:

So after re-looking at the plane files it appears as though each plane has the below value:

 

P47
image.png.e8217e5559249f007ea79fddc735287b.png

 

P51

image.png.8db1d6c3b38cc115f6214b910e4448a0.png

 

(all appear to have the same value)

 

Unfortunately we don't appear to be able to edit the plane files without the game crashing, but wondering if this is something that can be updated?

 

sidenote: more than happy to do any additional testing if needed

How did you decide that 0.1 was the correct amount? I think you may find that your pattern is likely to change based on the map's ambient temperature.

 

Also, how are you accounting for distance in your measurements? If your measuring 10 cm of dispersion at 100m, then dispersion is 1 mil. However, if you measure 10cm  of dispersion at 200m, then the dispersion is .5 mil.   Based on your  P-47  example (4 mil 100%) at 610 meters all the rounds should fall with in 2.4 meters of the aim point. Then you also have to account for convergence. I'm just wondering how you account for those variables.

 

I know it doesn't seem like it, but I agree with your assessment that the dispersion is too low. I actually think it's much to low.  Given what's visible in the files. 

 

From what I can tell a few separate files define the accuracy parameters of the gun.

The aircraft file located in: \luascripts\worldobjects\planes\

The weapon file located in: \luascripts\worldobjects\weapons\mg_usa_m2-50.txt

 

Dispersion Data for the M2 .50 cal is also located in

\luascripts\worldobjects\weapons\mg_usa_m2-50.txt

 

Where we find:

BulletDispertionAngleData = 0.0, 0.6, 700.0, 3.5 // base VO 0.1 thousand range cold, 1 thousand hot, corrected in vepon modes

 

More detailed instructions are found in the same directory \luascripts\worldobjects\weapons\guninstruction.txt

 

BulletDispertionAngleData = 0.2, 0.5, 700.0, 6.0 

// The law of increasing the angle of dispersion of bullets (projectiles) relative to the axis of the barrel of small arms, depending on the absolute temperature of the barrel:
// the first number is the minimum (theoretical) angle of dispersion of bullets (shells) relative to the axis of the barrel of small arms at the absolute temperature of the barrel: Т = 0 ° K = -273.15 ° С, [°], (> = 0)
// second number - the angle of dispersion of bullets (projectiles) relative to the axis of the barrel of small arms at the absolute temperature of the barrel specified by the third number, [°], (> = first number)
// the third number is the absolute temperature of the small arms barrel, at which the second number specifies the scattering angle of bullets (shells) relative to the axis of the small arms barrel, [° С], (> -273.15
// fourth number - the degree of dependence of the angle of dispersion of bullets (shells) relative to the axis of the small arms barrel from absolute temperature of the barrel of small arms, [dimensionless], (> = 1)

 

The M2 50 cal is

BulletDispertionAngleData = 0.0, 0.6, 700.0, 3.5

Based on the instructions we can say;

When the barrel temp is -273.15 ° С, there is zero degrees of dispersion, When the barrel gets to 700c degrees the dispersion is .6 degrees. The scaling coefficient is 3.5.

 

My first question was how does this scaling coefficient effect the dispersion pattern. To test I put a P-39 with 50 cal only at 3000 m in Kuban Fall map.  I maxed out the coefficient high and low.  First we increase the value  a lot.

BulletDispertionAngleData = 0.0, 0.6, 700.0, 10000 

This reduce the dispersion effects to almost nothing, until the guns reach over 700c. Once the gun temp is over 700c, the dispersion went to max dispersion and above as long as the trigger was held down. The bullets would return low dispersion when the gun was allowed to cool.

 

Next we change the value to it's lowest setting.

BulletDispertionAngleData = 0.0, 0.6, 700.0, 1

According the instructions, 1 is the lowest value the coefficient can have. Thus we set it to 1. The result: dispersion begins to increase before the barrel reaches 700c.

 

 This value seems to effect how much dispersion is applied per unit of barrel heat.  Thus it looks like we scale the dispersion from 0.0 to .6 degrees based on the barrel temp from -273 to 700c. With result divided by the scaling factor.  It may end up something like this

Dispersion in degrees = ( Barrel Temp * 0.00061 / Scaling Factor)

 

I then wanted to see if the guns start out -237c or are they effected by the ambient temperature. To test we'll max the scaling coeffiect so that rounds are not effected by the barrel temp until the barrel temp is above the critical temp. Are test setting looks like this.

BulletDispertionAngleData = 0.0, 90, 15, 10000

The theory of operation here is, only when the guns get above 15 c the will they start dispersing wildly 90 degrees.

 

To test we put a P-39 on the ground in Stalingrad in the winter. Here we get  ~3 shots before the guns start to disperse. Which makes sense because the guns heat up 4.659 degrees per shot. From our weapon file.

BarrelTemperatureIncreasePerShot = 4.659

We then test on the summer map. Here the 50 cals shoot wildly from the start, As they are ambient temp which is above 15 c.

I think we can say that guns start at ambient temp, Do I want to test the alt to temp gradient in the sim and see if that has an effect on these parameters. No but I think it's sufficiently modeled. 

 

As noted each aircraft has a value that can increase the dispersion. It's defined as, and is loacted in that aircraft's lua file.

eg: \luascripts\worldobjects\planes\_

CarriageAdditionalBulletDispertionAngle = 0.019100955, 0.03820191" 

A guide to this files contents is found in:

\luascripts\worldobjects\planes\_weaponmodesinstruction.txt

CarriageAdditionalBulletDispertionAngle = 0.0, 0.0 
// Additional angles of dispersion of bullets (shells) relative to the axis of the small arms barrel, due to the design features of the small arms carriage:
 // the first number is the additional scattering angle at the first shot in the queue, [°], (> = 0) 
// second number - additional scattering angle for the second and subsequent shots in the queue, [°], (> = first number) 

This looks like it adds an additional few degrees of dispersion to our dispersion. Since I have no way to test this variable, I can't tell if it's added before or after the scaling factor:

EG: is it, this for the first shot:

BulletDispertionAngleData = 0.0191, 0.6, 700.0, 3.5 

or this

Dispersion in degrees + .0191 = (Delta Barrel Temp * 0.00061 / Scaling Factor)

 

 

Your setting of:

BulletDispertionAngleData = 0.1, 0.6, 700.0, 3.5

On a standard day, at an alt 2400 meters, where the temp ~0c, Your mod may change the base dispersion to:

 

(0.00061  * 273 + .1)  / 3.5 = 0.0761 degrees = 1.32 Mils

 

Accounting for the added dispersion from the the carriage effects the total dispersion may equal:

 

(Base dispersion.0761) + (Carriage effect .0382) = 0.114 degrees =1.99 mils 

 

or if it calculated differently:

 

(0.00061  * 273 + .0382  +.1 ) / 3.5= 0.087 degrees = 1.51 mils

 

 

Which is probably fine. Perhaps even low. The default settings seem to indicate the dispersion is low until the guns heat up. 

 

Taking our standard day conditions again we can expect an air temp of 0c degrees ~ at 2400 m. And compute out the base dispersion.

 

The stock game  dispersion would likely be  ~ 

.0382(aircraft added dispersion) + Dispersion in degrees = ( 273* 0.00061) / 3.5)

 

.0382 +  .0475  = 0.0857 degrees = 1.495 mil 

 

Or if the aircraft added dispersion is computed differently 

 

 Dispersion in degrees = (0.00061  * 273 + .0382)  / 3.5 = .0584 Degrees = 1.01 mils.

 

Here's where things get really interesting. When we talk about the concept of dispersion. The rating of gun, ie 4 mill 75% relates to the standard deviation from aim point. This relates to your mod because, you may have inadvertently nailed the right amount of dispersion for the gun at 0 degrees C.

 

The dispersion of the gun can be described by a probability function, if we assume the rounds are distributed normally. The US military uses this function. https://apps.dtic.mil/dtic/tr/fulltext/u2/a193618.pdf

 

It is:

Dispersion diameter = 2 sigma * sqrt chi square critical probability for 2 dof of the % of the radius

Where sigma is the standard deviation from impact point.

 

We know the 50 cal is rated at 4 mil 75%, inputting this into our formula:

 

4 mil = 2 * X * sqrt 2.77

 

Solving for X gives us the Standard deviation of the round in either the X or Y axis.  Which is  1.22 mils. Since the round can deviate in both the Y and X axis the formula says the standard deviation for the round is 2 sigma. Thus the diameter of standard deviation of the 50 cal ap round is 2.44 mils. Your mod of 

BulletDispertionAngleData = 0.1, 0.6, 700.0, 3.5

 

Likely results in a dispersion diameter, (1.99 mils). That is much closer to reality than the default setting.  Not sure how you got there but, seems to be very close. However temperature variations will likely result in higher dispersion, especially at sea level.


A final note: a sanity check on degrees or rads.

Spoiler

 

A final note; I wanted to do a sanity check that everything was in degrees. So I set up a test: See If i could get the bullets dispersing 180 degrees,  backwards.

we test two setting one set for rads


BulletDispertionAngleData = 0.0, 3.142, 15, 10000

The other set for Degrees.


BulletDispertionAngleData = 0.0, 180, 15, 10000

We put a P-39 on the ground in the summer and shoot the guns. Only the setting for 180 degrees dispersion at 15c resulted in the rounds going backwards.

 

 

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Awesome stuff @Yak_Panther! Thanks for putting this all together. I'll admit it took a few reads through as maths isn't my strong point (angular maths especially so). 

 

On 4/12/2021 at 3:32 AM, Yak_Panther said:

How did you decide that 0.1 was the correct amount? I think you may find that your pattern is likely to change based on the map's ambient temperature.

Bit of guess work and testing. I wasn't sure whether more than 1 decimal place would be accepted and just wanted to see if a quick solution is possible. I only did the mils test on the deck during the evening so the tracers were more easily visible. 

 

On 4/12/2021 at 3:32 AM, Yak_Panther said:

Also, how are you accounting for distance in your measurements?

The only effective way I could find to measure this was by utilising the convergence settings. The dev notes state 4 mils at 2000ft, so I set the convergence to 610m (~2000ft) and then fired a short salvo with the time compression slowed to 1/32. You then know, once the rounds begin crossing in the sight they are at approximately 2000ft and you can take measurements (sizing the site up to 10cm and the measuring out mils in mm). The convergence in the game is a perfect point, so we know all the guns are aimed at the same pixel. 

 

Will do some more testing and see how much OAT affects the dispersion. I wonder if the game models the gun heating systems on the P51 and P47? I understand that temp outside may be <0° C, but would this mean the barrel temp is that? Always more questions...

 

I was aware of the relationship between the high and low dispersion settings and that increasing the lower number would mean a quicker onset. Am I right in thinking that a change to the variable would mean you could keep the same curve despite the smaller gap between the numbers?

 

The main approach for this was to make it simple and do as much legwork as I could for the devs so it would be easily implementable for them. I know their commitment to making sure the sim is as historically accurate as possible, whilst balancing what the engine and develop timelines allow. The magic number for 6 mil dispersion probably lies between 1 - 1.5 so will try some additional numbers between there and mess around with the variable. 

 

 

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On 4/14/2021 at 1:22 AM, ACG_Cass said:

Will do some more testing and see how much OAT affects the dispersion. I wonder if the game models the gun heating systems on the P51 and P47? I understand that temp outside may be <0° C, but would this mean the barrel temp is that? Always more questions...

I don't think the heating system is modeled, there doesn't seem to any indication of it in the file structure.  The best way to test the effect of temperature on the the effects of dispersion is. To conduct the testing on the ground at the same runway, then vary the season in the editor to change the temps. IE Going from winter to summer.

 

I like to use The P-39 here because the 50 cals guns are basically level, due to the tricycle style landing gear. There's also only two guns, so its a bit easier to observe the rounds. Ground testing also minimizes the recoil effects, since the guns return to basically the same spot after a short burst. Unlike an aircraft in motion. 

 

The best way to measure the dispersion would be to fire while on the ground at a target of a known size and distance.

On 4/14/2021 at 1:22 AM, ACG_Cass said:

I was aware of the relationship between the high and low dispersion settings and that increasing the lower number would mean a quicker onset. Am I right in thinking that a change to the variable would mean you could keep the same curve despite the smaller gap between the numbers?

I'll break down my calculation a bit more. That way you can play with the variables as you see fit.  I actually made an error in my previous calculation, I'll show where. Then we can see how it effects the calculated dispersion. The error also relates to your question about the curve.

 

We'll take your dispersion setting and calculate the dispersion step by step.

BulletDispertionAngleData = 0.1, 0.6, 700.0, 3.5

From the previous post, we know what each of these variables is supposed to do. Now let walk through how they are applied to determine the dispersion angle. 

 

Let's look at the previous example for these dispersion settings where the barrel temperature is 0c. We determined the base dispersion before the aircraft effects were 1.32 mil or .0761 degrees. It's important to note the variables the game uses are degrees for angular measurement and degrees of Celsius for temperature. The previous equation was.

 

(0.00061  * 273 + .1)  / 3.5 = 0.0761 degrees = 1.32 Mils

 

The first number in our equation (0.00061) is the base amount of dispersion per degree of barrel temp. This is computed by subtracting the max dispersion from the min and dividing by the the total number of degrees that the dispersion happens over. 

Dispersion Max - Dispersion Min / Absolute Value of Temprature Degrees Min and Max

 

From our variables above it looks like something like this:

.6-.1 / 973.15 = 0.000513

We know the min  (.1) and max dispersion(.6). The total amount of dispersion that occurs is .6 - .1 = .5 

 

The .5 dispersion happens over the temperature range of -273.15 to 700 degrees, or 973.15 degrees.  

 

Thus the dispersion per degree of barrel heat is; .00051.  As .5/973.15 =.00051

 

Meaning for every 1 degree rise in barrel temperature the dispersion increases by .00051 degrees. This is where I made my error in my previous post. I used a dispersion per degree of barrel temp of .00061, because I forgot to account for your .1 in this part of the calculation. We'll see how this effects the outcome going forward.

 

Onto the next part of the Equation: 273. This is the difference between the barrel temp and absolute zero. The difference between 0 degrees and -273 deg is 273. Which is why we use it to calculate the dispersion at 0 degrees c. If we we're checking at 20c we would use. 273 + 20 = 293 degrees to calculate the base dispersion.

 

We multiply the dispersion per degree (.00051) * Delta in Barrel temp from -273 (273) to give us the temperature modified base dispersion.

 

.00051 * 273 = .139 degrees of temp modified base dispersion.

 

Back to our equation, lets now correct it and apply the variables for your mod. The equation for your mod now looks like this.
(0.00051  * 273 ) +1 = .239

 

The .1, is the min dispersion value from the  gun setting file. We have to add this to the temperature modified  base dispersion( .139) because the gun starts with .1 degree of dispersion. So the net amount of temperature modified dispersion is .1+.139 = .239 degrees of net temp effected dispersion.

 

We then scale net temp dispersion by the scaling coefficient defined by gun parameters. In this case 3.5. I believe that we divide the net temp dispersion (.239) by the scaling factor (3.5).  This gives us the total amount of gun dispersion 

 

.239/3.5 = .0682 degrees of calculated gun dispersion.

 

{(0.00051  * 273 + .1)}  / 3.5 = .0683

 

But we still need to account for the added dispersion from the aircraft carriage variable defined in the Aircraft.txt. It's .0382 so we just added  it to total computed dispersion.

 

{(0.00051  * 273 + .1)}  / 3.5 = .0683 + .0382 = total amount of dispersion. =.1065 degrees of dispersion.  To convert degrees to mills, multiply by 17.777 which give us 1.89 mils

 

Thus

{(0.00051  * 273 + .1)}  / 3.5 = .0683

.0683 + .0382 = .1065 degrees

.1065 * 17.777 = 1.89 mils.

 

Therefore, your mod puts out around 1.89 mils radius of dispersion when the guns are zero degrees.

I know it was a long way to get there but I wanted to lay it all out as clearly as possible.

On 4/14/2021 at 1:22 AM, ACG_Cass said:

I was aware of the relationship between the high and low dispersion settings and that increasing the lower number would mean a quicker onset. Am I right in thinking that a change to the variable would mean you could keep the same curve despite the smaller gap between the numbers?

All things be equal, When we change the min and max dispersion variables. We alter the slope of dispersion per degree. To keep the curve the same the min and max both have to increase at the same rate.  If you want to keep the slope of the same in your mod you would increase both min and max by .1.

 

Your mod changes the amount of dispersion per degree to .00051. Because were moving from .1 to .6 a change of .5 degrees. The base game moves from 0 to .6 degrees. Therefore the amount of dispersion per degree is .0006.  If you want to keep the slope the same in your mod you would need to increase both number the same amount. To keep the base game's slope the same in your mod the min dispersion of your mod should be .1 and the max .7 . This would give you .006 degrees of dispersion.

as .1 -.7 = .6

 

What kind of effect will this have? Lets see what happens before we take into account the aircraft effects.

First the base mod.

{(0.00051  * 273 + .1)}  / 3.5 = .068 degrees of dispersion = 1.21 mils

Now we keep the slope the same as base, by transforming .00051 to .00061

{(.00061* 273 + .1)}  / 3.5 = .076 degrees of dispersion = 1.35 mils

 

A change so small that it would probably impossible to measure it accurately. .So I wouldn't worry to much about the slope of the dispersion per degree of heat. I went and made spread sheet calculator if you want to play with the variables.

 

https://docs.google.com/spreadsheets/d/1R9M0ESAPI_amWheTN25fItMNCNLnPVSUFLGhXkjVz4k/edit?usp=sharing

 

Inputs are Min (B) and Max dispersion (C), the Temp At Which Max Dispersion Occurs (D), The Scaling Effect (E), the Barrel Temp (G) and Aircraft Effects (K). Changing one will give you the total dispersion in cells B11 in Degrees and B12 in Mils.

Edited by Yak_Panther
clarification, and order of opp errors.
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Brief description: 

 

P-47 damage model seems to be rendering higher damage than IL-2 Stat Page


Detailed description, conditions:

 

I searched all 5 pages of this thread looking for other reporting on damage model for P-47. I found nothing.

Lots of comments in other sections, but nothing here.

P-47 Damage on stats in showing 10% but rendered far worse in game. Is this a bug to render more than reported or vice versa, is IL-2 Stats in the wrong and damage worse than 10%?


Additional assets (videos, screenshots, logs): Attached IL-2 Stats page and in game screen shots (MP - Unprofessionals Server - Sunday 4.18.2021)


Your PC config data (OS, drivers, specific software):

 

Windows 10

Intel i9-9900k - 5.0 GHz

MSI MPG Z390 MB

32GB DDR4 3200MHz RAM

GeForce RTX 2080 Super 8GB 

HP Reverb G2

 

 

I appreciate you looking into this and if previously addressed, my apologies as I did search the forums.

 

S!

Hollywood

 

P-47 Damage Stats.png

Il-2 Sturmovik 4_19_2021 5_11_38 PM.png

Il-2 Sturmovik 4_19_2021 5_12_01 PM.png

Adding additional screen shot

 

 

 

 

 

 

Il-2 Sturmovik 4_19_2021 5_10_59 PM.png

Il-2 Sturmovik 4_19_2021 5_11_29  v.2.png

1513001944_Il-2Sturmovik4_19_20215_12_45PM.thumb.png.727cf4ad9dd2861595d762f3aed616d1.png

P-47 Damage percentage.PNG

Edited by AH_Hollywood
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Is there something wrong with Spit XIV? it seems as if the speeds, although shown  in Km/h (in the HUD) are actually in MPH, as high G loads are achieved even with gentle pull on the stick. I've switched HUD on and pressed I key to see g-load, and it is excessive for that speed (500 Km/h and really gentle pull on the stick), as 4-5 g are achieved almost instantly.

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1 hour ago, daliborsky said:

Is there something wrong with Spit XIV? it seems as if the speeds, although shown  in Km/h (in the HUD) are actually in MPH, as high G loads are achieved even with gentle pull on the stick. I've switched HUD on and pressed I key to see g-load, and it is excessive for that speed (500 Km/h and really gentle pull on the stick), as 4-5 g are achieved almost instantly.

 

Spitfires are just about neutrally stable in pitch, making them very fast to respond to elevator input, but also very sensitive. You only need to move the stick a tiny bit, and then possibly neutralise it, to hold a steady turn, just like the real thing. If anything, my initial impression is that the XIV is a little more stable in pitch than the V and IX in IL-2 GB, though you still have to be careful.

 

Not sure about the HUD, as I didn't really look.

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7 hours ago, daliborsky said:

Is there something wrong with Spit XIV?

Yes, it is very wrong. It is rubberbanding like in the old days. @AndyJWest is right that the Spit is sensitive to elevator input, this mostly due to a very far aft CoG, making it very neutral in control. It makes the aircraft want to always follow the stick input immediately, and it makes the Spit a very aerobatic aircraft, as if she was telling the pilot to do maneuvers, encouraging it. You feel utterly confident doing maneuvers. She is very easy to fly in maneuvers. (Within reason.)

 

The Spit moves its nose so readily and proportionally (in the practical range you use the stick inputs) and you don‘t need much input. But she follows your hand immediately and without rubberbanding or wobble. Think of your hand being directly connected to her nose and wings. Adding half a ton on the Mk.IX will not change that fact. And if so, that total change in behaviour would have been noted. And that is not the way such changes have been described.

 

The self tightening of circles is due to the far aft CoG, increasing AoA will shift the center of lift. But again, the poor controls due to this rubberbanding make this an issue. You are constantly fighting an aircraft that has her own mind with poor and indirect controls.

 

This

6 hours ago, AndyJWest said:

You only need to move the stick a tiny bit, and then possibly neutralise it, to hold a steady turn, just like the real thing

is the antithesis of the real thing. If the real thing was like that, they would not have built more than one of it.

 

We got a train load worth of sim artifacts.

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I have flown military jets from 60' and some other aircraft too, so I have plenty of stick time. I was wondering that there is someting wrong with speed conversion (internaly) as very tiny stick movment in pitch results in 4-5 g loads, which is not correct. I've tested that in some other planes in IL2 and they allow much more concrete movements of the stick withouth g-overload. OR - transition of the stick movement to simulated Spit is wrong, i.e. the stick movement (joystick) equals much bigger input in "real", i.e. simulated spit.

 

I'm aware of the fact, that Spit was very eager to follow input in pitch, but the problem I have is that I move my stick by milimeters and already graying out.

Edited by daliborsky
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1 hour ago, daliborsky said:

I'm aware of the fact, that Spit was very eager to follow input in pitch, but the problem I have is that I move my stick by milimeters and already graying out.

I agree it's overdone now. The thing is in the real aircraft, inputs are so precise that it doesn't really bother you that you that she is so responsive once you get used to control forces not being harmonic. I mean, same as with the ailerons, it takes very little deflection to make her roll or pitch. But if you want a lot of roll or pitch, then you still use plenty of deflection. You should never worry about how she's react to an input, because you know it.

 

If you have stick time from 60' jets then she might be a tad less precise in the center, as cables are clearly inferior to pushrod arrangements.

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