Fluid systems - damage models?

[Whacker]

My friends, crabby ol' Uncle Whacker is in need of some education.

As of 4.11hotfix, I'm trying to ascertain exactly what's modeled in terms of damage to systems that contain fluids. This includes fuel, oil, coolant, and hydraulics. What I understand is covered are the following:

1. Damage to fuel tanks is modeled. When damaged, the tanks will leak fuel in the form of a light white stream behind the aircraft from whichever fuel tank was hit. The plane will leak and stream fuel like this until the affected tank(s) is/are empty. Questions: if the message "fuel tank damaged" shows up, does this mean the tank is damaged and self-sealing (if applicable) failed? Does it mean the fuel tank was damaged and self-sealing worked? Does it just mean fuel tank damage irrespective of self-sealing?

2. Damage to the oil/lubrication system is modeled. If hit or damaged, the windscreen will show the "oil splash" graphic. The aircraft will trail a darker black smoke. Questions: Does the aircraft trail smoke only until the oil runs out? Until the engine quits? Forever? Is the amount of smoke generated variable, and does it depend on the amount of damage?

3. Damage to the coolant systems is NOT modeled. Question: Any plans to include this in future patches?

4. Damage to the hydraulics systems is modeled. Questions: Does this create any "streaming fluids" like the fuel system? I don't recall it ever doing so. If yes, what does it look like?

Please see my questions, and correct any wrong information.

[Luno13]

I believe the game HUD message for damaged fuel tanks is simply: "fuel tank: leak". It doesn't give any info as to whether or not it has or will re-seal. You can only watch the gauge and find out.

The game also models 3 levels of fire: thin grey smoke, thick black smoke, and full-on fireball. The thin grey smoke typically burns all the fuel in a matter of minutes. There is no way to stop this, which is why I'm lobbying for fuel-tank selectors. The thick black smoke also burns fuel quickly, but after a random amount of time, it will almost certainly develop into a fireball, killing the player, exploding the tank, or melting the wing spar.

The fire can be put out with great speed, but will always return. I think some more variability should be implemented here, and I think an empty tank shouldn't keep burning forever (unless I'm wrong about that).

The engine burns in a similar way to fuel tanks, which is why a fuel-cutout valve should be added. Some planes had extinguishers for the engine, but as far as I'm aware, this is only implemented in the Avia B.534 and bombers. The PZL.11 had a jettisonable fuel tank.

Thin grey smoke from an engine however, typically is caused by burning oil. It's not the only indication of damage, though. I've had shot-up engines whine and seize without any smoke at all, or even damage textures visible on the cowling. Maybe this is an indication of coolant damage?

As far as I know, coolant was mostly some glycol mix, and should look like leaking fuel (thin white stream). If it's in the DM, it certainly isn't represented visually.

There are no streaming fluids from hydraulics, but I imagine the reservoirs for those aren't as large as for fuel and oil tanks. Hydraulic damage only affects landing gear, but some aircraft had a system which used a valve to control flaps, cowl flaps, etc. from the same reservoir. Other aircraft had pneumatic systems, which can't be damaged, or simply act like hydraulic systems. Hand-pumping landing gear systems are impossible to damage.

O2 lines and bottles aren't modeled, but it would add an interesting element to the DM.

It's worth mentioning, though a little OT, that engine controls can be damaged, causing the throttle to be stuck at the last setting it was left at. There is no HUD text to indicate this. Damage to control lines affects the control and trim, but this wasn't always the case (there are stories of guys flying back using only trim after controls were shot out).

[BadAim]

One thing to keep in mind, Mate is that the code base is c13 years old now. Granted it has been greatly improved over the intervening years, but there's only so much that can be done.

I have seen fuel leaks in self sealing tanks, stop after a few minutes, indicating a slightly delayed reaction (which is historical from my understanding), other times the damage is just too great and the tanks drain out, so I'm with Luno; it would be nice to have even a simplified system to allow for say having only the holed tank drain out and not the whole system, if not a full tank selector system.

The rest I think would need a TD member to answer.

Interesting questions though.

Oh, yeah I just thought that run away props are modeled too. It's very common it spit's and P-40's, less so in other planes.

[Grach]

I was under the impression that fuel systems are treated rather generally as one big tank in the game.

I recall an experience in a TB-3-4M17 which suffered a fuel leak in one wing and some while later had all four engines cut out simultaneously. No fuel left in the gauges... Now, while I'll pay a TB-3-4M17 not having self sealing tanks, one would suspect that there would be a multitude of individual tanks and valves/plumbing to prevent this sort of thing happening on the real thing.

I'd be interested to hear what the situation in the game actually is.
Still, as BadAim points out, it's not doing too badly for a sim that was designed around one featured aircraft over a decade ago...

[Untamo]

Originally Posted by Whacker

2. Damage to the oil/lubrication system is modeled. If hit or damaged, the windscreen will show the "oil splash" graphic. The aircraft will trail a darker black smoke. Questions: Does the aircraft trail smoke only until the oil runs out? Until the engine quits? Forever? Is the amount of smoke generated variable, and does it depend on the amount of damage?

Being mainly a 109 pilot I get oil splatters a lot, even a AAA gun crew looking angrily at it makes it to spill its oil supply

There are 3 kinds of oil leaks, depending on amount of damage:
1) Mild leak, thin black smoke coming out. Does not smudge the windscreen, but you can notice the mild smoking in the cowling. Easily misinterpreted as fuel leak seen from other planes. The trail is the same but more black. Not dangerous and you can in most cases operate the engine with normal power output for about 10-30min, after which the engine starts to lose power slowly. Haven't seen cases that this would get worse with just engine mismanagement.

2) Medium leak, medium thickness black smoke. About the same thickness as when putting out that brownish smoke when having too rich mixture setting. More dangerous, engine starts to lose power after a couple of minutes and will usually die after 10min. Medium smoking can become heavy leak(!) in some cases, usually something to do with high RPM and overheat (or getting more damaged of course ).

3) Heavy leak, thick black smoke, the smoke now also makes little puffs instead of just a steady stream when coming out. Very dangerous in 109, usually leads to a fire and explosion within seconds. Recommend bailing immediately. In some other planes (bombers mostly) I've seen they can last in the heavy smoking state longer (few minutes) before catching on fire, but they always do eventually.

Common to all:
You can't get better ... Even when you run out of oil and the engine has stopped, you will still have a smoke trail. Maybe the smoke is related to a small fire that is going on in the engine which might get worse as in point 2.

[Whacker]

Originally Posted by Untamo

Being mainly a 109 pilot I get oil splatters a lot, even a AAA gun crew looking angrily at it makes it to spill its oil supply

There are 3 kinds of oil leaks, depending on amount of damage:
1) Mild leak, thin black smoke coming out. Does not smudge the windscreen, but you can notice the mild smoking in the cowling. Easily misinterpreted as fuel leak seen from other planes. The trail is the same but more black. Not dangerous and you can in most cases operate the engine with normal power output for about 10-30min, after which the engine starts to lose power slowly. Haven't seen cases that this would get worse with just engine mismanagement.

2) Medium leak, medium thickness black smoke. About the same thickness as when putting out that brownish smoke when having too rich mixture setting. More dangerous, engine starts to lose power after a couple of minutes and will usually die after 10min. Medium smoking can become heavy leak(!) in some cases, usually something to do with high RPM and overheat (or getting more damaged of course ).

I honestly haven't ever seen a difference between these two. Whenever I get hit, it's either "thin" or "thick" black smoke. Thin smoke will cause the engine to go south pretty quickly unless you nurse it along, but it'll almost always sound like hell warmed over after about 5-10 minutes. If I can keep it in the air long enough it'll eventually quit on me. The smoke trail doesn't ever go away though, that I'm positive of now.

3) Heavy leak, thick black smoke, the smoke now also makes little puffs instead of just a steady stream when coming out. Very dangerous in 109, usually leads to a fire and explosion within seconds. Recommend bailing immediately. In some other planes (bombers mostly) I've seen they can last in the heavy smoking state longer (few minutes) before catching on fire, but they always do eventually.

Dunno about "seconds", I've seen a few AI planes get hit bad enough to have the thick black smoke, and limp along for upwards of 2-3 min before the fires start. Once the fire starts, the crew will always bail unless they're dead.

As an aside, I did a quick mission with me in a P-47D vs. an H8K1 over Okinawa. I shot it up pretty good, started a fire on the underside of it. Let it go to see how long it would last. It kept flying on fire for about 5 minutes before I realized I forgot to turn on autopilot and crashed. This was in DBW 1.71 on 4.10.1, but I still found it rather amusing.

[Untamo]

I have no extensive experience about these in other aircraft so I can't say anything about them, but this is the case for the 109... in all versions of IL-2.

In it, the thin smoke isn't a reason for panic and quick RTB as is the case for the medium smoking which will start to decrease your engine power quite quickly.
The heavy smoking has a umm... 80% chance of fire within less than 30s and it always ends in an explosion just a couple of secs after catching fire.

[Luno13]

I think the thickness of the thin smoke you are referring to is caused by two layers of the regular thin-smoke texture (smoke in il-2 is rendered in 2-D, but always faces the camera to look more voluminous; this was important to save resources).

The two layers are coming from the engine and possibly fuel tank, or both from different parts of the engine. Because they are in line with each other, the smoke looks "thicker" even though it's the same texture.

This doesn't happen with most other planes. As such, there are still only 3 classes of fire: thin grey smoke, thick black smoke, and fireball. The only thing that really varies is the damage it does and how long you have until you explode. Still, it's not bad for a really old game.

[TBear]

Im kinda an avid onliner.

Doing BFT`s it was normal to train new pilots on how to estimate visual damedge.

Pilot A say think something is wrong. Pilot B flyes up close to him and estimate the visual damedge of the plane.

That is a problem ofline or playing point servers

But that is how we do it

[Untamo]

Originally Posted by Luno13

I think the thickness of the thin smoke you are referring to is caused by two layers of the regular thin-smoke texture (smoke in il-2 is rendered in 2-D, but always faces the camera to look more voluminous; this was important to save resources).

The two layers are coming from the engine and possibly fuel tank, or both from different parts of the engine. Because they are in line with each other, the smoke looks "thicker" even though it's the same texture.

Cannot agree with this. In the 109 there are 3 distinct oil leak levels before full on fire.

As I described on the point 1, there is also the smoke coming under the cowling(seen from the cockpit) which is much lesser than what is coming under medium smoking, described in point 2. And to more separate the light smoking from the medium, the light one doesn't smudge the windscreen with oil.

But both create black smoke behind the a/c. These too are very distinct from each other. The light smoking stream doesn't dissipate in the same way as the medium smoke. The light smoke trail stays the same width when the a/c gets further, but the medium smoke starts to fan out, getting wider before fading away.

The heavy smoking is also distinct from the two lesser ones in the way it makes the puffs of smoke along with the stream of smoke, which is also a bit more darker and wider than in the medium smoking.

Originally Posted by Luno13

This doesn't happen with most other planes. As such, there are still only 3 classes of fire: thin grey smoke, thick black smoke, and fireball. The only thing that really varies is the damage it does and how long you have until you explode. Still, it's not bad for a really old game.

I think I have seen these in the Spit too, but I think the variation is much lesser. Usually they only go for the "medium" type. Cannot be sure though. Don't usually have so much time to analyze them so properly .. But one clear heavy smoker champion is the Mig.. shoot at the wing root with couple of 20mms and heavy smoke comes out, and very soon the thing is on fire