reported P-51 engine does not quit when overheated

[Art-J]

10 hours ago, Gunfreak said:

So now I have to actually watch the temperature gauges and fly accordingly instead of following a "recipe"? Think I'm gonna try the blue nose bastard campaign again.  Gave up on mission 2. As I couldn't keep up with the AI flight 

Keep in mind every airplane out there has its own defined Vx and Vy (speed for best angle of climb and speed for best rate of climb), same for best speeds for continuous turn rate, various speed limitations etc. Thus, the "recipes" are still useful to remember. This 170 for the Mustang climb came from manual, I recall (?).

We can, however, push the -51 somewhat harder now, worrying about cooling a bit less than we did previously. 

 

Edited August 28, 2022 by Art-J

[grafspee]

31 minutes ago, Art-J said:

Keep in mind every airplane out there has its own defined Vx and Vy (speed for best angle of climb and speed for best rate of climb), same for best speeds for continuous turn rate, various speed limitations etc. Thus, the "recipes" are still useful to remember. This 170 for the Mustang climb came from manual, I recall (?).

We can, however, push the -51 somewhat harder now, worrying about cooling a bit less than we did previously. 

 

 

This is good point.

But before latest patch those speed were unavailable for P-51 sometimes even for 46/2700 rpm, i could only dream to climb mil power at 170mph  now i can do it, finaly.

Edited August 28, 2022 by grafspee

[NineLine]

On 8/24/2022 at 2:39 PM, amazingme said:

  I abused the P-51 for ~15 mins in zoom climbs or turning climbs with speeds even below 100mph, the coolant temp was at max, the oil temp was also at max (rads were on Auto, engine @ mil power). At some point it loses coolant (when reaching 0mph) but after recovering some speed it runs normally again after the coolant temp drops (I've tried that a couple of times).

The track is ~8MB so I uploaded to wetransfer.com: https://we.tl/t-GCJzVTWhUc

L.E. I've tried now with WEP climbing @90mph, the coolant was escaping, engine still running. Track attached.

server-20220825-005845.trk 1.81 MB · 4 downloads

Cheers!

 

Thread kinda got crowded but I will look soon.

[Jafferson]

My engine quit without overheating and sooner, like less duribility after the patch.

[Doughguy]

This can have a couple of reasons.

[NineLine]

1 hour ago, Jafferson said:

My engine quit without overheating and sooner, like less duribility after the patch.

If you are seeing something off, send in a track.

[NineLine]

On 8/24/2022 at 2:39 PM, amazingme said:

  I abused the P-51 for ~15 mins in zoom climbs or turning climbs with speeds even below 100mph, the coolant temp was at max, the oil temp was also at max (rads were on Auto, engine @ mil power). At some point it loses coolant (when reaching 0mph) but after recovering some speed it runs normally again after the coolant temp drops (I've tried that a couple of times).

The track is ~8MB so I uploaded to wetransfer.com: https://we.tl/t-GCJzVTWhUc

L.E. I've tried now with WEP climbing @90mph, the coolant was escaping, engine still running. Track attached.

server-20220825-005845.trk 1.81 MB · 5 downloads

Cheers!

 

Great track @amazingme, later in the track I do see you hold some very high temps for a decently long time, it does seem odd there is no apparent affect. I will look into it deeper. Thanks!

At the end there it seems you did have an occasional release of coolant, but never a full overheat, what was more concerning was the oil temps. 

[Hobel]

 

vor 2 Stunden schrieb NineLine:

Great track @amazingme, later in the track I do see you hold some very high temps for a decently long time, it does seem odd there is no apparent affect. I will look into it deeper. Thanks!

At the end there it seems you did have an occasional release of coolant, but never a full overheat, what was more concerning was the oil temps. 

As far as I have been able to observe, the damage is always different under absolutely the same conditions.
One time the engine gives up after 3 minutes and another time after 5 or 10. The values differ, of course, depending on how the engine is loaded.
Is such dynamic behaviour desirable?

 

I just did another test and the engine dies after ~13min web
Military afer ~30min
This can also happen sooner or later

 

Is the engine supposed to stall shortly after the time limits in the manual are exceeded, or is the behaviour described by @grafspee intended?

Am 28.8.2022 um 08:01 schrieb grafspee:

Those time limits on engine are  for engine life time, because engine was designed to work through many hours of flight so manufacturer says if you want this engine run fine through 600hours you need to do this and this. Exceeding time limits do not mean immediate failure.

 

BUT

The engine only suffers damage in the DCS P51 if the cooling fluid is in critical areas for too long - the oil does not seem to have any effect.

Here the track shows the whole thing I think well

I have had the coolant at a good temperature all the time and the oil could boil for ~40min without harming the engine, I think that shouldn't be?

40min P51 .trk

Edited August 31, 2022 by Hobel

[NineLine]

Yes, that is my thoughts as well, seems you can run the oil with the temp gauge pegged for ever, even the oil doesn't seem to thin much, at least for some time. I will ask about this, internally overheating works well if the gauge is pushed, but seems to be a disconnect with oil temps.

As for the damage being different, this is a good thing, engines are dynamic, all parts while should be created equal can fail differently, this will give a less scripted feeling to engine damage for sure.

[grafspee]

@Hobel If we talk about coolant max operation temperature, the main limiting factor back in ww2 was design of coolant radiator, germany with poor radiators design could run up to 100C in early B-109 and spitfires could run up to 130C which forced Germans to use double size of radiator to provide same cooling.  

So coolant temp limit is related mainly how high pressure cooling system can operate. But for engine it is very little difference, only what happens is that coolant pressured is safe guarded by pressure vent so when you overheat you start loosing coolant and at some point heat transfer deteriorate and engine dies due to internal overheat.

Oil does not boil at temps below 200-300C so boiling oil off is not an option, what happens is at some point it stops lubricate engine and it kills engine much faster.

Oil behavior is quite strange, try inverted flight and oli pressure remains steady whole time, manual states that 10s is max, prop governor stops working which indicates that oil supply to governor is stopped but oil pressure gauge remain unchanged.

Edited August 31, 2022 by grafspee

[grafspee]

I found old bug report which was reported but it contains same issue, oil temp way above limit just does not do anything.

It isn't tagged as fixed tho.

 

Edited August 31, 2022 by grafspee

[Hobel]

vor 6 Minuten schrieb grafspee:

So coolant temp limit is related mainly how high pressure cooling system can operate. But for engine it is very little difference, only what happens is that coolant pressured is safe guarded by pressure vent so when you overheat you start loosing coolant and at some point heat transfer deteriorate and engine dies due to internal overheat.

exactly and so far this is also happening in DCS
at a certain point the engine dies here

 

vor 6 Minuten schrieb grafspee:

Oil does not boil at temps below 200-300C so boiling oil off is not an option, what happens is at some point it stops lubricate engine and it kills engine much faster.

The maxiumum of the oil gauge in the P51 is 100C I think that should cause damage if you hold it too long?

[grafspee]

Just now, Hobel said:

The maxiumum of the oil gauge in the P51 is 100C I think that should cause damage if you hold it too long?

Oil temp is scaled to 100C but god knows who high it can go actually.

Max temp of oil in P-51 is 95C as manual, it is mentioned in part about WEP use, it can get to 95 for 5 min or so.

If oil temp stops at 100C you probably go away with it, if it goes higher like up to 150C then engine won't last long

[NineLine]

11 minutes ago, grafspee said:

Oil temp is scaled to 100C but god knows who high it can go actually.

Max temp of oil in P-51 is 95C as manual, it is mentioned in part about WEP use, it can get to 95 for 5 min or so.

If oil temp stops at 100C you probably go away with it, if it goes higher like up to 150C then engine won't last long

Yeah, and thats what I need to check, is the oil hitting an unrealistic limit and not getting hotter or is it getting hotter and just not responding corectly

 

[Hobel]

vor 38 Minuten schrieb NineLine:

Yeah, and thats what I need to check, is the oil hitting an unrealistic limit and not getting hotter or is it getting hotter and just not responding corectly

 

yet the engine should not survive that long when the red line is crossed or the indicator is at 100? and that is the case at the moment.
57min shows the gauge 100C with closed Oil cooler and I think it should be significantly more

the display is not stuck either. in the end i can cool the oil down again.

57min P51.trk

Edited August 31, 2022 by Hobel

[NineLine]

Thanks for the track, I am reporting this issue now.

I'll leave this open for now because the OP was about overheating, but currently I am not seeing an issue with that, although its harder to overheat now, its probably more like it should be. 

[OLD CROW]

I attach the track of this bug, track seems corrupted, but even that I attached it. I've observed both rads temps went stable (needles come back to green safe zone)  and engine gone into "god mode" (engine can be pushed beyond their performing and timing limits) even in WEP only after receiving some light scratches from one of those 109 I was fighting. When A/C is fresh cooling systems work as should be. All dogfight has been performed with engine at 3000 RPM's and MP between 50 and 64 Hg Inches on the deck. 

 

Cooling_Bug.trk

[NineLine]

I'll take a look, thanks.

[ShadowFrost]

Since this applies to other aircraft and probably all under the new temperature model I'll just add this data bit here for consideration. Most mineral aviation oils start to thermally breakdown near 270F so at that point you will see a rather extreme drop off in lubricating performance. If the temp gauge indicates 100C the temperature reading is likely near 212F at the oil temp pickup point. Internally, the oil will be anywhere between 30-60 degrees hotter (f) within the engine at specific points. 

 

Brand new engines and even used WW2 engines IRL have been known to take serious punishment and modest overheats (generally water coolant). For the purposes of DCS I don't imagine you should have much issue running an engine excessively hard below this oil limit, however, above this limit you are entering dangerous territory for once the degraded oil reaches a critical component it will likely serious damage the engine within a short period of time. The oil temp limit is especially important. Coolant less so. But generally speaking, if you keep an engine within temperature limits you should be able to run it as hard as you like.

Sure, there are other factors like shock cooling an engine (radials) but most things are maintenance concerns and really don't impact DCS. 

 

Edit- There is an assumption here that a temperature between 212 and ~270 F (the thermal breakdown point) is not critical. It could be very possible that a temperature within this range reduces the oil beneath the minimum needed lubrication amount and can accelerate wear/damage the engine before reaching the 270F/thermal breakdown point. This is a possibility, however, this is unknowable to me. The oil would almost certainly reach this limit at the thermal breakdown limit if it has not reached such a limit sooner. 

 

Edited September 11, 2022 by ShadowFrost

[NineLine]

On 9/7/2022 at 2:56 AM, OLD CROW said:

I attach the track of this bug, track seems corrupted, but even that I attached it. I've observed both rads temps went stable (needles come back to green safe zone)  and engine gone into "god mode" (engine can be pushed beyond their performing and timing limits) even in WEP only after receiving some light scratches from one of those 109 I was fighting. When A/C is fresh cooling systems work as should be. All dogfight has been performed with engine at 3000 RPM's and MP between 50 and 64 Hg Inches on the deck. 

 

Cooling_Bug.trk 2.94 MB · 2 downloads

Sadly you just crash into the ground on play back, if you can give me as many steps and events that happened in the track I will try and recreate. It sounds like an interesting bug, if indeed the engine is becoming invulnerable at some point. 

[OLD CROW]

Mission is the INSTANT ACTION DOGFIGHT VS 109 in Channel map

After merge first I started chasing 109 wingman on the deck. Wingman then started an extension just for putting me in a drag & bag situation. I noticed that maneuver I didn't follow the wingman's tight turn to the right. I check high 6 and I spotted leader diving while cutting the corner on me, so I pulled flap 1 and started to pull back gradually the stick, just to perform a breaking turn to the right and pull hard just when I noticed he reached the shooting distance. I evaded the main spray but he managed to put a few bullets in my left wing, nothing important as I checked visually (no big holes in the wing, just small holes done by shrapnel in the inner  part of the wing). I hadn't noticed any change in A/C FM: no lack of lift, no extra drag, no lack of control in any flying surface, no lack of engine performance... nothing remarkable ( I only noticed the visual damages 2 maneuvers after due I checked my 6 looking for the 109). Due the break turn I burnt a good amount of energy, so I decided to pull flap 2 and perform flat scissors just to force his overshooting due he had a lot of energy in the first dive. We did 2 flat passes and I converted the flat scissors into a rolling scissors just performing a barrel roll to force him the overshot if he wanted to keep the energy high or sacrifice a big amount of energy just to start a a very low energy combat on deck. I guess AI is not programmed for choosing the second solution (as  a human opponent normally does), so after the barrel roll we were on deck flying in paralel, he was on my 10-11 OC. 109 can build up energy faster than P-51. He started to extend away. I retracted flaps to position 1 and I slowly tried to put my nose in an very gently intercepting course, just to build a shooting window and put a few shots on him. As soon I pointed my gunsight on him he firstly turned tight right and then due his energy advantage he started to perform a breaking turn that he converted into a chandele to the right: enough relaxed for him to keep my nose out of any decent shot but enough tight for forcing me to mantain my engine in 3000 RPM's and full MP in case I decide to stay in the turn. We performed this ascendent turn for almost 2 complete turns. During those turns I had enough time for checking rads temps, last time was I checked temps was when I first was chasing the wingman and cooler needle was green but going to red zone and oil temp needle was in the bottom of the green box but dropping to the red zone too. Then I had to perform all that shaky-shaky jinking with the leader and after completing first chandele turn I noticed my MP was at 64 inches for, what I judged, too much time, but before relaxing throttle I decided to check temps and.... There they were!!!! after all that engine abuse needles were in green boxes and with no apparent movement or visual tendency to the red zone. Even that I decided to pull back MP into 59-60 but that slowered the A/C enough so he began to get away from my 2-3 OC. I stayed in the turn for another three quarters of a turn pushing and pulling throttle from 60 to 64 a couple of times more, just for experimenting with the needles (dogfight was already lost: he was building energy and I was on deck burning energy trying to keep his turn, so it would had been a matter of time he dove on me again or the wingman came after me) cause it was weird and confusing how could it be possible needles were marking good temps after all that shake at low speed solid as a rock. At this point I quitted mission thinking track was short enough for evading the possible corruption. I saved the track, went back to playback menu and.... the rest is history.

Maybe due the heat of the battle I could had missjudged the engine endurance timing, but in what I have zero doubts is how fast oil and coolant temps increase in mustang as soon as rads intake air flow is hindered or fully cutted and the fact I started the fight chasing wingman with rads temp going red, performed all jinks and shaking maneuvers with the leader that hindered fresh air in rads, perform an extension at 3000 RPM and MP in WEP (64 Inches)  position and then perform a chandele for almost 2 complete circles made me reaching the conclusion I've experimented any similar bug what you described in august 31 and its possible generator could be in the Damage Model.

I Hope it would be helpful. Regards.

[Hammock]

Man that was just fun to read!

2 hours ago, OLD CROW said:

Mission is the INSTANT ACTION DOGFIGHT VS 109 in Channel map

After merge first I started chasing 109 wingman on the deck. Wingman then started an extension just for putting me in a drag & bag situation. I noticed that maneuver I didn't follow the wingman's tight turn to the right. I check high 6 and I spotted leader diving while cutting the corner on me, so I pulled flap 1 and started to pull back gradually the stick, just to perform a breaking turn to the right and pull hard just when I noticed he reached the shooting distance. I evaded the main spray but he managed to put a few bullets in my left wing, nothing important as I checked visually (no big holes in the wing, just small holes done by shrapnel in the inner  part of the wing). I hadn't noticed any change in A/C FM: no lack of lift, no extra drag, no lack of control in any flying surface, no lack of engine performance... nothing remarkable ( I only noticed the visual damages 2 maneuvers after due I checked my 6 looking for the 109). Due the break turn I burnt a good amount of energy, so I decided to pull flap 2 and perform flat scissors just to force his overshooting due he had a lot of energy in the first dive. We did 2 flat passes and I converted the flat scissors into a rolling scissors just performing a barrel roll to force him the overshot if he wanted to keep the energy high or sacrifice a big amount of energy just to start a a very low energy combat on deck. I guess AI is not programmed for choosing the second solution (as  a human opponent normally does), so after the barrel roll we were on deck flying in paralel, he was on my 10-11 OC. 109 can build up energy faster than P-51. He started to extend away. I retracted flaps to position 1 and I slowly tried to put my nose in an very gently intercepting course, just to build a shooting window and put a few shots on him. As soon I pointed my gunsight on him he firstly turned tight right and then due his energy advantage he started to perform a breaking turn that he converted into a chandele to the right: enough relaxed for him to keep my nose out of any decent shot but enough tight for forcing me to mantain my engine in 3000 RPM's and full MP in case I decide to stay in the turn. We performed this ascendent turn for almost 2 complete turns. During those turns I had enough time for checking rads temps, last time was I checked temps was when I first was chasing the wingman and cooler needle was green but going to red zone and oil temp needle was in the bottom of the green box but dropping to the red zone too. Then I had to perform all that shaky-shaky jinking with the leader and after completing first chandele turn I noticed my MP was at 64 inches for, what I judged, too much time, but before relaxing throttle I decided to check temps and.... There they were!!!! after all that engine abuse needles were in green boxes and with no apparent movement or visual tendency to the red zone. Even that I decided to pull back MP into 59-60 but that slowered the A/C enough so he began to get away from my 2-3 OC. I stayed in the turn for another three quarters of a turn pushing and pulling throttle from 60 to 64 a couple of times more, just for experimenting with the needles (dogfight was already lost: he was building energy and I was on deck burning energy trying to keep his turn, so it would had been a matter of time he dove on me again or the wingman came after me) cause it was weird and confusing how could it be possible needles were marking good temps after all that shake at low speed solid as a rock. At this point I quitted mission thinking track was short enough for evading the possible corruption. I saved the track, went back to playback menu and.... the rest is history.

Maybe due the heat of the battle I could had missjudged the engine endurance timing, but in what I have zero doubts is how fast oil and coolant temps increase in mustang as soon as rads intake air flow is hindered or fully cutted and the fact I started the fight chasing wingman with rads temp going red, performed all jinks and shaking maneuvers with the leader that hindered fresh air in rads, perform an extension at 3000 RPM and MP in WEP (64 Inches)  position and then perform a chandele for almost 2 complete circles made me reaching the conclusion I've experimented any similar bug what you described in august 31 and its possible generator could be in the Damage Model.

I Hope it would be helpful. Regards.

 

[grafspee]

Still w/o track it is impossible to say is it a bug or not, maybe engine temps stayed with limits all the combat.

Why you can see temps being near red line and sometimes in green arc? This is how this termo regulator system works it opens cooling shutters at certain temp but closing temp is different lower then opening temp so there is a little range where shutters won't close even when temps drops, so sometimes you will fly with higher temps sometimes with lower temps.

There is old oil temp bug which indeed makes engine invulnerable to oil temps even running oil cooler closed and reaching 100C has no consequences,

It was reported april 16 2021 so some time has passed and by look of it recent cooling updated affected coolant only, for me oil behave haven't changed, maybe when ED release remaining part of this new cooling will fix that.

I only hope that it will happen sooner not later

Edited September 13, 2022 by grafspee

[OLD CROW]

5 hours ago, Hammock said:

Man that was just fun to read!

????......

Happy to make you having fun. Unhappy you have not contributed anything constructive to this thread. For next times don't waste your time in reading long reports... type your owns and share the fun with others.

 

2 hours ago, grafspee said:

Still w/o track it is impossible to say is it a bug or not, maybe engine temps stayed with limits all the combat.

Why you can see temps being near red line and sometimes in green arc? This is how this termo regulator system works it opens cooling shutters at certain temp but closing temp is different lower then opening temp so there is a little range where shutters won't close even when temps drops, so sometimes you will fly with higher temps sometimes with lower temps.

There is old oil temp bug which indeed makes engine invulnerable to oil temps even running oil cooler closed and reaching 100C has no consequences,

It was reported april 16 2021 so some time has passed and by look of it recent cooling updated affected coolant only, for me oil behave haven't changed, maybe when ED release remaining part of this new cooling will fix that.

I only hope that it will happen sooner not later

Could be plausible. I attached the track thinking they could recover it somehow. Maybe it was only my hunch... who knows... track is corrupted. Let's see how all this will develop also when all A/C's got the FM-DM reviewed. Cooling system is an step forward the way it has been implemented, but needs some fine adjustments. 

[Hammock]

2 hours ago, OLD CROW said:

????......

Happy to make you having fun. Unhappy you have not contributed anything constructive to this thread. For next times don't waste your time in reading long reports... type your owns and share the fun with others.

 

Could be plausible. I attached the track thinking they could recover it somehow. Maybe it was only my hunch... who knows... track is corrupted. Let's see how all this will develop also when all A/C's got the FM-DM reviewed. Cooling system is an step forward the way it has been implemented, but needs some fine adjustments. 

What I meant was that it was like you took the reader on the flight with you during the dogfight. It was like reading an account from a WW2 pilot!  Awesome!