Bf-110 C4N - poss engine oil temp bug (stb engine)?

[ATAG_Ezzie]

I've noticed this a few times but havent been able to screen capture it until just now when i had a long one engined flight back to Theville from the IOW (S Maru!).

It seems the engine oil temp of the stb engine is somehow linked to the engine oil temp of the #1 engine -maybe?. During this sortie due to damage i had to throttle my port engine (#1) down to zero throttle with the radiators closed and pitch at 0830 as per standard single engined SOPs. I opened the radiators of the good engine (#2) to fully open and flew the rpm/ata at the continuous setting.

What is interesting is the oil temps.

The #1 oil temp dropped to 81 degrees which is expected given the zero throttle. However the #2 engine oil temp was also showing 84 degrees despite it still working and operating at continuous setting with rads fully open. Normally the #2 engine oil temp is around 92 when in typical cruise mode with radiators at 50-50. So 84 seems a tad low.

Ive attached some screen grabs showing the #1 and #2 engine oil temps and rpms etc.

20170827195412_1.jpg20170827195427_1.jpg20170827195455_1.jpg20170827195504_1.jpg20170827195713_1.jpg


Intuitively i would not expect #1 and #2 engine oil temps to have similar temps given the different operating configurations (#1: zero throttle, fuel still on, 0830 pitch fully closed rads; #2 continuous settings for rpm and ata, fuel still on, rads fully open) and i'm wondering if the #2 engine oil temp is modelled to just be similar to whatever # 1 is at the time (ie #1 temp plus a few degrees) maybe to simplify the coding? But i could be wrong.

Before i log it I'd be interested in what others think. Does it make sense for these 2 engines to have similar oil temps despite different operating conditions or is there something unusual going on. Again its not a big deal but just thought i'd raise it and perhaps log it for investigation down track perhaps?

Ezzie

[ATAG_Ezzie]

2nd time lucky

Did a quick test offline with one of the quick missions. Set up level flight at continuous settings with rads fully open and took screen grabs of the temps (#1 92, #2 89)

20170827205246_1.jpg20170827205255_1.jpg

Throttled #1 back to zero throttle and 0830 pitch and re-established level flight. Took screen grabs that showed the temp drop on #1 to 80 and #2 to 83

20170827205405_1.jpg20170827205417_1.jpg

I hadnt done anything to the #2 engine which was still operating at the same rpm and ata and yet its oil temp had dropped by 6 degrees. This strikes me as odd?

Ezzie

[ZG26_Sir_Racha]

I have noticed this too. I didn't look into it much, just figured the engine was running off both sets of rads or something wacky.

[RAF74_Buzzsaw]

Thanks, will have a look.

[Artist]

Hi Ezzie,

Thanks, will have a look.

now you definitely can put it in the bugtracker. It is not simply *not a bug*.

Cheers,
Artist

[Erpr.Gr.210_Mölders]

Maybe Ezzie in the first post add also a link to the first discussion about it so it will be easy to cross-check if needed.

[Artist]

Maybe Ezzie in the first post add also a link to the first discussion about it so it will be easy to cross-check if needed.

Standard requirement of Bugtracker entries: Link to the discussion in the forums...

[ATAG_Ezzie]

Hi Ezzie,



now you definitely can put it in the bugtracker. It is not simply *not a bug*.

Cheers,
Artist

Will do later this week hopefully Artist.

Ezzie

[ATAG_Ezzie]

Maybe Ezzie in the first post add also a link to the first discussion about it so it will be easy to cross-check if needed.

Molders - is there an earlier discussion? I did a quick search but couldnt find any - could u post the link if there is an earlier discussion and i will include it.

Ezzie

[Erpr.Gr.210_Mölders]

Molders - is there an earlier discussion? I did a quick search but couldnt find any - could u post the link if there is an earlier discussion and i will include it.

Ezzie

No mate sorry I've confused the previous discussion about the fuel tanks with this...it's the age...

[ATAG_Ezzie]

Will do later this week hopefully Artist.

Ezzie

Artist - just added this to bug tracker as requested.

Ezzie

[ATAG_kiwiflieger]

Took a look at this over the afternoon today, can confirm what Ezzie experiences. Here are my test results for oil temperature:

Bf 110 C-4, Rads W60-O40 except when closed on inop engine. Temps all in degC.

Left engine shutdown
Before: L 94 R 91
After: L 78 R 85

Now here's the weird bit:

Right engine shutdown
Before: L 94 R 91
After: L 94 R 81

Shutting down the right engine on the 110 has no effect whatsoever on the left, but not vice versa! Water temperatures were unaffected by each other and only by their own engine state.


Also noticed something else weird, when you fully feather the engine to stop the propeller from rotating there is the message "Engine Stopping", and if you unfeather the engine back to full fine pitch it will only achieve about 1200 RPM at full throttle. Selecting the affected engine and hitting the "Toggle Selected Engines" binding, or start, it jumps straight back to normal RPM with no engine start message! I noticed that when I tested the right-hand engine in this state it could still drive the hydraulics for gear and flaps at normal speed.

[RAF74_Buzzsaw]

Pleaes add this to the bugtracker.

Took a look at this over the afternoon today, can confirm what Ezzie experiences. Here are my test results for oil temperature:

Bf 110 C-4, Rads W60-O40 except when closed on inop engine. Temps all in degC.

Left engine shutdown
Before: L 94 R 91
After: L 78 R 85

Now here's the weird bit:

Right engine shutdown
Before: L 94 R 91
After: L 94 R 81

Shutting down the right engine on the 110 has no effect whatsoever on the left, but not vice versa! Water temperatures were unaffected by each other and only by their own engine state.


Also noticed something else weird, when you fully feather the engine to stop the propeller from rotating there is the message "Engine Stopping", and if you unfeather the engine back to full fine pitch it will only achieve about 1200 RPM at full throttle. Selecting the affected engine and hitting the "Toggle Selected Engines" binding, or start, it jumps straight back to normal RPM with no engine start message! I noticed that when I tested the right-hand engine in this state it could still drive the hydraulics for gear and flaps at normal speed.

[ATAG_kiwiflieger]

Done

[MicroWave]

I don't think there is a bug here. It seems the radiator is very efficient even on the ground(?), so I performed the worst case scenario test.
Start on the ground.
Shut down engine #1 (magnetos off).
Close oil radiator for #2.
Press full wheel brakes.
Throttle max engine #2.
Results in slow spinning around on the ground.
Fairly soon oil temp on #2 went to 110 C, while temp on #1 remained around 80 C.
Started new mission and doing opposite for #1 and #2.
Oil temp on #1 went to 110 C, on #2 lingered around 80 C.
So, all good more or less.

But...
There seems to be a problem with water temps. Wrong engine water radiator blew up
in both cases (when #1 running, rad blew on #2 and vice versa). Instruments actually
show what game engine supplies (#1 stopped, #1 water temp goes high, while on #2 it
remained steady, which is exactly opposite of what is expected). Even the smoke (I guess
water vapor) started from the wrong engine.
The correct water rad actually blew only when there was damage on the oil system reported.
I tried He-111, same thing. Ju-88 looked OK, Beau looked OK.
If you are interested, you can repeat those tests on all available twin engine planes and report
so maybe I can find a common denominator (it could be 3d model, flight model, damage model,
bug in the code). I tried a few things, but I couldn't find anything wrong.

[Tibsun]

But...
There seems to be a problem with water temps. Wrong engine water radiator blew up
in both cases (when #1 running, rad blew on #2 and vice versa). Instruments actually
show what game engine supplies (#1 stopped, #1 water temp goes high, while on #2 it
remained steady, which is exactly opposite of what is expected). Even the smoke (I guess
water vapor) started from the wrong engine.
The correct water rad actually blew only when there was damage on the oil system reported.
I tried He-111, same thing. Ju-88 looked OK, Beau looked OK.
If you are interested, you can repeat those tests on all available twin engine planes and report
so maybe I can find a common denominator (it could be 3d model, flight model, damage model,
bug in the code). I tried a few things, but I couldn't find anything wrong.

It has been somewhere reported that the He-111 blows rads on the wrong side even when shot.
This is as far as I know not true for the Bf 110 and I think also not true for the Ju-88 - could be wrong about the Ju-88 though.

[ATAG_Ezzie]

I don't think there is a bug here. It seems the radiator is very efficient even on the ground(?), so I performed the worst case scenario test.
Start on the ground.
Shut down engine #1 (magnetos off).
Close oil radiator for #2.
Press full wheel brakes.
Throttle max engine #2.
Results in slow spinning around on the ground.
Fairly soon oil temp on #2 went to 110 C, while temp on #1 remained around 80 C.
Started new mission and doing opposite for #1 and #2.
Oil temp on #1 went to 110 C, on #2 lingered around 80 C.
So, all good more or less.

But...
There seems to be a problem with water temps. Wrong engine water radiator blew up
in both cases (when #1 running, rad blew on #2 and vice versa). Instruments actually
show what game engine supplies (#1 stopped, #1 water temp goes high, while on #2 it
remained steady, which is exactly opposite of what is expected). Even the smoke (I guess
water vapor) started from the wrong engine.
The correct water rad actually blew only when there was damage on the oil system reported.
I tried He-111, same thing. Ju-88 looked OK, Beau looked OK.
If you are interested, you can repeat those tests on all available twin engine planes and report
so maybe I can find a common denominator (it could be 3d model, flight model, damage model,
bug in the code). I tried a few things, but I couldn't find anything wrong.

H MW,

Thanks for looking into this. Interesting results you got. If i get a chance i will see if i can replicate my earlier results in the air and then do what you did on the ground etc.

Do you know what -110 variant you used when you did the spinning on the ground test?

Ezzie

[MicroWave]

I used Bf 110 4CN.

[ATAG_Ezzie]

OK so i did some more testing. All online using sealion map.

First test was on the ground and i opened up both sets of radiators on #1 and #2 and then only turned on #1 and opened throttle up to ~ 25%. #1 engine temp and oil temp went up and #2 stayed down

Slide6.JPGSlide7.JPGSlide8.JPGSlide9.JPG

I then shut down#1 engine and watched the water temp rise until it got to about ~ 120 and then it blew - correct engine damage message shown and correct visuals

Slide11.JPG

Second test - repeated the test but this time used #2 engine with everything else the same. Same result including blowing the correct water radiator.

Third test - same as above but had both engines running but advanced the throttle on #1 to ~ 50%. #1 oil and water temps went up and #2 stayed down

Slide27.JPGSlide28.JPG

Slide29.JPGSlide30.JPG

So based on these test on the ground it appears that #1 and #2 engine and oil temp readings are independent of each other as MicroWave concluded earlier.

Fourth test - went flying and established level flight at 2K alt on ~ 30min settings with temp readings showing what i normally see (these are taken as i climbed to 2K)

Slide32.JPGSlide33.JPGSlide34.JPGSlide35.JPG

Shut down #1 engine leaving #2 more or less untouched re settings (some uncommanded changes did happen to pitch and ata but reconfigured) and watched what happenned. #1 temps dropped and so did #2 which is odd given the engine was running pretty much unchanged (I reset it to 30 min continuous settings)

Slide39.JPGSlide40.JPGSlide41.JPGSlide42.JPG

I flew back to base on one engine (#1 feathered) and watched temps. #1 dropped some more but #2 stayed at about the same temps.

Slide43.JPGSlide44.JPG

So the airborne temps seemed to confirm that #1 and #2 oil and water temps are independent of each other. But i'm not sure why #2 temps dropped when #1 was feathered given it was more or less working just as hard. And the aircraft was eventually much slower and i would have thought velocity would have some effect on temps ie if the engine is working just as hard but the aircraft is going slower then the temps should increase if airflow is being used in the cooling system. Maybe?

This might be totally legit behaviour and normal given how this system is designed / modelled. But it does seem a tad counter-intuitive.

But at the end of the day this isnt a show stopper in my opinion - there's only a very small number of people who fly -110s and only a small subset of them who probably fly often on a single engine and it doesnt provide any real advantange/disadvantage in my opinion. But if its a symptom of some underlying issue with engine cooling/heating that affects more than just the -110 it might be worth exploring some more.

Perhaps a Blennie flyer could repeat the above and see what happens?

Happy landings...

engine_temp.jpg

Ezzie

[Tibsun]

I didn't came to test anything about this topic yet, though I want to give you the note that since 4.5 the water cools more rapid than before.

Because of the cooling being best at low altitude, the temps go lower than 4.312 at sea level as an effect of the rapid cooling.

But temps do still rise normal above limits, when using full throttle and max rpm at full throttle-height with max boost available (+12lbs for Spit and Hurri).