Damage Model Bug Stomping

[Pursuivant]

This is a continuation of the FW-190 Durability topic, and the work I did prior to the 4.13 release.

Using RPS69's test mission as a base, I've been working my way through the single-engined propeller fighters, testing their vulnerability to engine fire and wing breakage when fired upon at point-blank range by .50 caliber MG fire.

Each "mission" consists of setting up a B-25J on the runway, with the target plane immediately behind it at a distance of approximately 20 m, then blazing away using the twin .50 caliber guns in the tail to pour concentrated fire onto the engine and wings.

I use unlimited ammo to give myself sufficient firepower and arcade mode to judge exactly where my shots hit. At such short ranges, there's almost no chance of missing or hitting anything other than the intended parts of the target.

Tests consist of waiting until the target plane starts it engine and runs it up to operating temperature, then firing on the engine to see if a fire occurs. Once the fire starts, I start walking bullets along one wing until the wing breaks.

When shooting at the wing, I always try to aim at the leading edge so that the bullets would penetrate the main wing spar in real life. Realistically, the intense concentration of .50 caliber fire through the spar should cause a wing collapse, even when the plane is parked on the ground. (Mind you, this should be a difficult thing to achieve in aerial combat, I'm only testing whether a particular plane has parts which can be broken using .50 caliber fire.)

Typically, only 5-10 seconds of fire is necessary to trigger the desired result. When an anomalous result occurs, the target plane will take enough damage to make it "vanish" (that is, lethal damage and despawn when the plane touches the ground) after about 15-30 seconds.

Here are my results so far:


Buffalo Series (B-239, F2A, Buffalo Mk I) - Engine fires: yes. Wing breakage: No, regardless of where the bullets hit.

CW-21 - Engine fires: yes. Wing breakage: Yes, wing breaks at midpoint, but will not break at the wing root.

Fokker D-XXI series (Danish & Dutch): Engine fires: yes. Wing breakage: Yes, wing breaks at midpoint, but will not break at the wing root.

F4F series (F4F-3, F4F-4, FM-2) - Engine fires: yes. Wing breakage: Yes, but only for hits to the outer wing. Aiming anyplace else on the wing will not break it, either at midpoint or at the wing root.

The fatal damage texture/breaking parts for outer wing damage represents damage that the F4F was provably able to survive!

F4U series (F4U-1A, F4U-1C, F4U-1D, Corsair I, Corsair IV) - Engine fires: yes, but only after 8-9 seconds of concentrated and continuous point blank fire. The fire might represent a fuel tank fire rather than an engine fire. Wing breakage: Yes, but only for hits to the extreme outer wing. Aiming anyplace else on the wing will not break it. Aiming anyplace else on the wing will not break it, either at midpoint or at the wing root.

The fatal damage texture/breaking parts for outer wing damage represents damage that the Corsair was provably able to survive!

F6F series (F6F-3 late, F6F-5) - Engine fires: Yes. Wing breakage: Yes, but only for hits to the outer wing about 3 yards/meters in from the wingtip. Aiming anyplace else on the wing will not break it, either at midpoint or at the wing root.

FW-190A series (FW-190A-4 to A-9, including mistel & ATA) - Engine fires: no. Wing breakage: Yes. Wing will break at both midpoint and wing root.

Fulmar - Engine fires: Yes. Just a few bullets will start a full-blown fire, so perhaps the engine catches fire a bit too easily. Wing breakage: Yes, but hits to extreme outboard wingtip cause the wing to break off just outside the landing gear. Hits to the inboard wing can't make the wing break off at the wing root.

Hurricane Series (Mk I, Mk IIb, Mk IIc, Field Mod) - Engine fires: Yes. Just a few bullets will start a full-blown fire, so perhaps the engine catches fire a bit too easily. Wing breakage: Yes. Wings break at both midpoint and at wing root. Good DM!

I-15bis series (I-15bis, I-15bis w/ skis): Engine fires: Yes. Just a few bullets will start a full-blown fire, so perhaps the engine catches fire a bit too easily. Wing breakage: Yes. Top wings break at both midpoint and at wing root. Bottom wing just breaks at wing root.

[Furio]

Good job. This is a simple but effective experiment, producing facts, rather than feelings.

[majorfailure]

Did a quick check:

UB(Pe-8 ) vs. Fw190D9 -engine burns, wings break
vs. F4F and F4U -same
.50cal(B-24) is not able to break wings - engine fire still possible.
neither Italian 7.7mm SAFAT nor MG81 can break any wings, but F4F engine can be set on fire.

[Woke Up Dead]

Did a quick check:

UB(Pe-8 ) vs. Fw190D9 -engine burns, wings break
vs. F4F and F4U -same

You sure it was the UB and not the 20mm cannon on the Pe-8? Cannons in the tail and on the back of that plane. The IL-4 has a UB on its back.

[majorfailure]

You sure it was the UB and not the 20mm cannon on the Pe-8? Cannons in the tail and on the back of that plane. The IL-4 has a UB on its back.

I had to turn the Pe-8, else you cannot fire from the engine gondolas, so yes, I'm pretty sure, and also the traces were pure white, and only white(IIRC ShvaK has slightly roseish and yellowish white traces), and RoF was what I would expect from a HMG not a cannon. And I did check what happens when firing from the top of a Pe-8, just to be sure, and the results are more devastating, engine gone in a few shots, wings usually break with first burst.

[RPS69]

Pursuivant, this is placed on the folder files/com/maddox/il2/objects.

The file is technichs .ini

; Number of shots to kill tank (panzer thickness(meters) \ energy)
[_TankShotPanzer_]
;thick\energy 0.00 7.62- 7.62 12.7 20.0 37.0 45.0 75.0 100 150
0 1000 3500 10000 27250 160000 300000 1100000 4800000 8000000
0.000 9999 60 10 2 0.0 0.0 0.0 0.0 0.0 0.0
0.005 9999 100 15 5 2 0.5 0.0 0.0 0.0 0.0
0.010 9999 400 35 20 8 0.8 0.1 0.0 0.0 0.0
0.015 9999 9999 1000 40 18 1.0 0.4 0.1 0.0 0.0
0.020 9999 9999 9999 700 28 1.3 0.5 0.2 0.0 0.0
0.025 9999 9999 9999 900 50 1.5 0.8 0.3 0.0 0.0
0.030 9999 9999 9999 2000 120 1.8 1.5 0.9 0.0 0.0
0.040 9999 9999 9999 9999 200 3 1.8 1.1 0.1 0.0
0.050 9999 9999 9999 9999 1000 10 5 1.5 0.6 0.0
0.070 9999 9999 9999 9999 9999 500 50 1.9 0.8 0.1
0.100 9999 9999 9999 9999 9999 2000 1000 6 1.0 0.5
0.150 9999 9999 9999 9999 9999 9999 9999 100 5 0.8
0.200 9999 9999 9999 9999 9999 9999 9999 800 200 15


That's how the game evaluate a penetration, that actually implies destruction of a ground object.
Air objects should not behave differently.
You may try to fire 9999 bullets on a wing, but I doubt it will actually break.

Also, there must be some damage boxes inside the wing that will trigger different effects. From what I tested, bigger planes got more damage boxes than small ones.

So, hitting the plane in different places may not break the wing in different patterns, because there will probably be just one box for the whole wing, unless someone coded a varied wing breaking pattern, it will probably be always the same.
Bigger planes got boxes for ailerons, so they can miss ailerons, but smaller ones appears not to have them.

If you start hitting them selectively, you will just be finding the boxes placement.

[KG26_Alpha]

Well iirc "hit boxes" are not used for aircraft DM.

Of course I will stand corrected but I'm sure a different method is used to damage the actual parts.

;)

Damage modelling explained in the link.

http://www.sas1946.com/main/index.php?topic=357.0

Damage
As explained in the general overview & parts & naming, an Il-2 aircraft is really a collection of parts flying in formation. There are three basic sets of parts, each corresponding to a "level" of damage. Levels are explained as follows:

D0 - No damage: This is the aircraft completely undamaged in normal running condition.
D1 - Light damage: Small holes from small or medium caliber machine guns and shrapnel.
D2 - Heavy damage is Light damage, plus large, threatening holes blown in the individual parts from cannon shells. Internal structure may well be visible, represented by D4 parts (see Caps & Internals page).

Note:
Perhaps some revisions may have taken place since the original post in later DT patches
I'm unsure but I would expect it to be untouched from the original concept.

[RPS69]

You know... from what I have read on that SAS post, damage boxes aren't overruled.
The collision objects aren't defined by modders.
They appear to be added after.

Nice guide BTW, thank you.

[Pursuivant]

I realized that comprehensive damage model testing reports aren't suitable for a standard forum thread. So, I'm in the process of creating a spreadsheet.

Results will be up in a few days once I've finished testing. At this point, I'm about 60% done. With 300+ aircraft in the game it's a lot of work!

I've also expanded the DM test to determine how all parts of the various planes stand up to concentrated .50 caliber fire from the front, as well as how AI handles damage.

Discoveries so far:

* The way that IL2 models wingtip damage is just wrong. Realistically, unless it's very lightly built or underpowered, almost any military plane should still be able to fly (sort of) if it's missing the outermost 10-15% of its wing.

Some very powerful and tough planes, such as the F4U, were noted for being able to fly home with up to a third of their wing missing!

But, IL2 models damage such that hits to the extreme wingtip cause a wing breakage at mid-wing - triggering fatal damage. For example, bullets which hit the last few feet of the wing will often cause the wing to break 3-5 yards inboard from the damage!

This might seem like a minor problem, but it means that most planes are far more vulnerable to wing hits than they should be, especially for ground attack missions (flak) or in hard-turning dogfights where sometimes the only shot your opponent can make on you is a wingtip shot.

* There is little consistency to wing breakage models. Aircraft like the P-51 can't have their wings broken by .50 caliber fire, but other planes of equivalent mass and construction (like the F6F or Tempest) can have their wings broken.

* The P-38, P-51 & P-47 series are invulnerable to wing breakage from .50 caliber bullets. This gives the late war USAAF fighters a huge and unfair advantage.

* The Buffalo series is invulnerable to wing damage. That explains why the B-239 is my favorite Finnish fighter!

* The A5M2 and A6M series are terribly vulnerable to wing breakage, perhaps unrealistically so. Just 3-5 .50 caliber bullets in any given wing section is enough to break a wing. In fact, the wing usually breaks before you can ignite the wing fuel tanks!

* There is little consistency in wing damage models. Planes like the Bf-109, FW-190, or Spitfire can have their wings shredded by fewer than a dozen .50 caliber bullets, while other planes of equivalent wing area can take far more damage before they show heavy damage textures.

* The Bf-109K series has slightly tougher wings than the earlier Bf-109s - despite having the worst production quality of the entire Bf-109 family. (Seriously, they were assembled by concentration camp inmates working in salt mines, made from parts shipped in from all over Occupied Europe, and their airframe lifespan was measured in terms of dozens of hours.)

* Engine damage models are a bit more consistent, but there is still some variation in the ability of the same engine to take damage based on the plane in which it is mounted. For example, the R-2800 mounted in the P-47 is much tougher than the same engine mounted in the F4U or F6F.

* The Rolls-Royce Merlin and Packard Merlin series engines are consistently very fragile, requiring slightly fewer hits to stop or to set on fire than the DB605 or Klimov M-105 series.

* Modeling of whether an engine catches fire seems to be linked to whether it stops - at least for most plane. The progression seems to be light damage > heavy damage > stop > fire. Realistically, once you get engine damage (i.e., chance of fuel or oil leak) the chance of engine fire should be separated from chance of engine stoppage. That is, you can still have an engine that runs - at least for a while - while it's on fire. For inline engines, which seem to catch fire almost as soon as they stop, there should be the chance of engine stoppage without fire.

* Fire results seem to be a bit extreme. Any damage which triggers a fire instantly causes a full-sized fire, rather than triggering a small fire which grows.

* Most crew won't bail out following a landing gear collapse on the ground.

* Damage modeling for landing gear is often quite crude - with tail wheels and landing gear struts often not being modeled. This is particularly true for the older planes in the game.

* There is no DM for flaps or air brakes - they don't take damage, can't be broken off & don't seem to contribute to wing damage.

* On many aircraft various externally-mounted vents and coolers aren't modeled. For example, the wing-mounted coolant radiators on the Bf-109 and Spitfire series aren't modeled. Kind of a big omission!

* Some planes, especially the really old ones, will have an explosion as a fatal damage effect - even if there are no bombs, ammo, or fuel in the fatally damaged areas.

* Broken parts, or sometimes the fuselage itself, will bounce around or tumble unrealistically, even on the ground. This is particularly true of some of the older planes.

[RPS69]

Pursuivant, after reading your post, I'm feeling guilty.
It is nice to do some tests, but we all know this game has it's flaws and limitations.
And unless someone on Daidalos team cares about what you are doing, it is almost a useless effort.
It will only help you to look at the game as a flawed one.
Take it easy pal.

[Pursuivant]

Pursuivant, after reading your post, I'm feeling guilty.
It is nice to do some tests, but we all know this game has it's flaws and limitations.

At this point it's an exercise in curiosity. I'm certainly not angry wiith IL2 for all that I criticize it!

I recognize that some things are impossible in the game, and that other things just aren't a big enough deal that DT needs to fix them.

In any case, DT, or modders, can pick and choose which DM errors they wish to fix.

[Pursuivant]

The results are in. Attached is a tab-separated text file which shows the results of point-blank twin .50 caliber MG fire against all the planes in the game. It can easily be turned back into a proper table in the word processor or spreadsheet of your choice.

In addition to lots of stuff that really can't be fixed, like the way that IL2 models wing damage and breakage, there are many things which can be fixed, including outright "hook" problems and DM omissions.

http://forum.1cpublishing.eu/attachment.php?attachmentid=15115&stc=1&d=1442263874

All of what I mentioned in my previous posts still stands. But, I'll add that many of the Japanese aircraft have really odd DM choices. For example, in terms of survivability, the Ki-43 series is far tougher than the A6M series, even though they were planes of comparable mass and size. The Ki-21 series also seems to be quite durable - possibly moreso than the G4M series. Arguably, the Japanese Navy aircraft should be made more durable.

In any case, it's clear that DM modeling is technically quite tricky and that there's no really good formula for doing it.

[Furio]

Thank you, Pursuivant, an excellent job!

I don’t think that our game is “flawed”. In my opinion it is (relatively) simple, but this simplicity allow us to have an unequalled planeset, today covering almost all major combat types and a lot of minor ones.

My feeling is that many of the inconsistencies tend to level out each other. For example, I never noticed that B239 wings are unbreakable, because it is relatively easy to break up its fuselage.

But the real value of your experiment is for us all. Now we have a lot of facts to read and ponder about, a reality check for all the claims about “porked” or “uber” planes.

Thanks again.

[falconilia]

* The P-38, P-51 & P-47 series are invulnerable to wing breakage from .50 caliber bullets. This gives the late war USAAF fighters a huge and unfair advantage.

If you fly historical air battles you dont have to worry about 0.50 caliber bullets but for lots of 20mms and some 13mm calliber (i think they are more powerfull but not tested).

So to minimize your results maybe you should test only vs Axis planes.
You will save time and strength!:) :)

[dimlee]

Many thanks for your work. The table is impressive.

Just two notes:
I-153 was indeed very vulnerable plane. According to German reports, it used to get fire quickly if hit by MG from the side.

Regarding "unfair advantage" of late USAAF fighters... Well, if P-38 does have any advantage it is annuled by ridiculous fragility of horisontal stabilisers and tail beams.

[RPS69]

If you fly historical air battles you dont have to worry about 0.50 caliber bullets but for lots of 20mms and some 13mm calliber (i think they are more powerfull but not tested).

So to minimize your results maybe you should test only vs Axis planes.
You will save time and strength!:) :)

I don't share your point of view.
Some Italian fighters have .50s as their only weapon. And they ARE vulnerable to .50s fire.

I also tested the effect of .50's on 190's, and even if they won't break their wings, it will become so unwieldy, that even an alive AI won't be capable of controlling it. That won't happen on a P51. Not with the same amount of fire.

[Pursuivant]

If you fly historical air battles you dont have to worry about 0.50 caliber bullets but for lots of 20mms and some 13mm calliber

Valid points, but one step at a time.

Future tests will determine vulnerability to side and rear attacks, as well as vulnerability to .30 caliber & 20 mm fire.

But, I'm limited by the selection of flexible guns mounted in flyable aircraft. Pe-8 for SHVAK, G4M for Type 99/Oerlikon FF 20 mm.

If anyone can recommend a flyable aircraft with twin .30/.303 caliber or 7.62mm flexible guns in a rear turret, I'd be grateful.


So to minimize your results maybe you should test only vs Axis planes.
You will save time and strength!:) :)

I chose .50 caliber as the mid-point in terms of weight of fire, and because the original focus of my test was determining if the FW-190's wing could be broken & its engine set on fire using that caliber of gun.

I might be making a mistake, but I also think that IL2 has "damage thresholds" required to damage certain aircraft parts. I'm guessing that the "damage threshold" classes are .30/.303 caliber & 7.62 mm, .50 caliber/12.7/13 mm, 20 mm & 30 mm. But, they might also be as simple as MG vs. cannon.

In any case, I'm assuming that any plane part which can be broken with .50 caliber/12.7 mm can be broken with rifle caliber MG, and that any part that can't be broken using .50 caliber/12.7mm can be broken using 20mm fire. I'm probably wrong, but further testing will tell.

[RPS69]

Valid points, but one step at a time.

In any case, I'm assuming that any plane part which can be broken with .50 caliber/12.7 mm can be broken with rifle caliber MG, and that any part that can't be broken using .50 caliber/12.7mm can be broken using 20mm fire. I'm probably wrong, but further testing will tell.

That assumption appears to be wrong. Riffle caliber may detach control surfaces on planes on which is enabled, but it won't cut wings.

You can't take out a whole aileron on any fighter, but you can do it on a Bf110, and many bombers. On those planes, rifle caliber will have the same effect.

[RPS69]

Pick a TB3. Lots of gun firing on many directions, and all rifle caliber.
You can also use a Bf110, or a Stuka.

The MG81, is a very fast shooter, and the MG81Z is the same thing, with double fire.

[majorfailure]

I don't share your point of view.
Some Italian fighters have .50s as their only weapon. And they ARE vulnerable to .50s fire.

Italian .50 SAFAT is not anywhere near other HMGs, low RoF, low muzzle energy - still concentrated burst can make plane parts break, it is possible to shoot off a Hurricanes tail or wing, but usually you get unspectacular kills - fuel tank/pilot/controls/control surfaces/engine dead.

I'm guessing that the "damage threshold" classes are .30/.303 caliber & 7.62 mm, .50 caliber/12.7/13 mm, 20 mm & 30 mm. But, they might also be as simple as MG vs. cannon.

Please test UB HMG against planes you thought invulnerable against .50 cal. If I am not totally mistaken, you can break Fw190/F4U/F4F wings with it.

[falconilia]

I don't share your point of view.
Some Italian fighters have .50s as their only weapon. And they ARE vulnerable to .50s fire.

I also tested the effect of .50's on 190's, and even if they won't break their wings, it will become so unwieldy, that even an alive AI won't be capable of controlling it. That won't happen on a P51. Not with the same amount of fire.

AXIS side for me are German/Italian/Japan/Romanian planes.
Im sorry if i didnt mention it.

I flew some test missions P51D vs P51D.
I didnt brake any wing but also i didnt have to.
Few hits and was on fire or thick smoke on engine or with even fewer hits on wing AI couldnt control it.

[Pursuivant]

I-153 was indeed very vulnerable plane. According to German reports, it used to get fire quickly if hit by MG from the side.

Unless there's a DM bug for a particular plane, just about all planes are quite vulnerable to being set on fire by .50 caliber bullets.

If anything, they're a bit too flammable, because fires start instantly once enough bullets hit a fuel tank, rather than starting out small and growing as more fuel spills from the tank.

A few planes are quite vulnerable to explosions. In particular, jet aircraft are quite prone to explosion, despite the fact that they either used regular 100/130 octane AvGas (i.e., no more flammable than any other fuel modeled in the game) or less flammable kerosene.

Oddly, the ME-163, which was fueled by a witches' brew of two highly flammable, corrosive chemicals can't be exploded!


Regarding "unfair advantage" of late USAAF fighters... Well, if P-38 does have any advantage it is annuled by ridiculous fragility of horisontal stabilisers and tail beams.

The P-38 also loses its engines quite easily.

In general, most aircraft in the game lose their control surfaces far too easily. Yes, the breaking parts effect is supposed to model lethal damage to a particular part, but often it's overdone. It's quite strange to see a giant piece of a bomber fall off due to just a dozen or so .50 caliber bullets.

[Pursuivant]

Please test UB HMG against planes you thought invulnerable against .50 cal. If I am not totally mistaken, you can break Fw190/F4U/F4F wings with it.

Is there a flyable plane in the game which has that weapon in a flexible gun mount?

[RPS69]

Is there a flyable plane in the game which has that weapon in a flexible gun mount?

IL2 3M, Pe2 and 3.

[Woke Up Dead]

IL2 3M, Pe2 and 3.

Except not the oldest series of the Pe2 in game.

[majorfailure]

IL2 3M, Pe2 and 3.
Also engine nacelle guns on Pe-8.

Does anyone know a useable platform for an Italian SAFAT 12.7mm or a German 13mm HMG?

[Torsteven]

Also engine nacelle guns on Pe-8.
You can add the dorsal gun on IL-4.
Also an Italian SAFAT 12.7mm
SM.79

German 13mm HMG?
He-111 H-12

[Pursuivant]

Thanks to everyone for the suggestions for different gun types. I will definitely be checking some of these out.

My new project is to revisit my first experiment using the M2 .50 caliber HMG, but to try firing on target aircraft from angles other than just the front. This should give me a good picture of how all breaking parts work in the game.

Results so far indicate that most aircraft in the game are far more vulnerable to airframe damage than their size and construction would indicate. In particular, just about every aircraft in the game is very vulnerable to damage to wing & control surfaces. Even if you can't break a particular aircraft's wing, it's often incredibly easy to trigger damage textures on it