wip Over-cooling

[Yo-Yo]

8 hours ago, Pyrocumulous said:

Attached is a track of the Spitfire engine degrading and failing at around +4 boost, 2200rpm while crossing the Channel at 20,000' with +1 degree surface temperature. This is with DCS 2.8.1.34667.1 Open Beta in Beware Beware Beware sortie #6. I don't know much about historic accuracy of the thermostats in these planes, but if they behaved like it's modeled, the war would have had a different outcome.

https://drive.google.com/file/d/1plguA4p1LcXSquDVHZbm6z6uGsITS1kd/view?usp=share_link

Did you clean the spark plugs periodically?

[NineLine]

19 hours ago, Pyrocumulous said:

Attached is a track of the Spitfire engine degrading and failing at around +4 boost, 2200rpm while crossing the Channel at 20,000' with +1 degree surface temperature. This is with DCS 2.8.1.34667.1 Open Beta in Beware Beware Beware sortie #6. I don't know much about historic accuracy of the thermostats in these planes, but if they behaved like it's modeled, the war would have had a different outcome.

https://drive.google.com/file/d/1plguA4p1LcXSquDVHZbm6z6uGsITS1kd/view?usp=share_link

I am watching the track right now, just at the beginning but you did taxi with quite a cool engine. 

[NineLine]

So I saw a similar failure at the roughly the same time even with taking care to warm the engine and make sure to clear the plugs, will keep investigating, will check a clean mission with same weather as well. 

[Pyrocumulous]

12 hours ago, Yo-Yo said:

Did you clean the spark plugs periodically?

No, I didn't clean the spark plugs, in fact, I was not aware that was possible. I do not see any mention in the Flight Manual or Chuck's Guide, and I am unable to locate a proper keybinding to accomplish that. How do I do it?

I generally let the engine oil warm to 20 degrees prior to taxiing, but even waiting until 15 degrees in Beware Beware Beware sortie 6 means you leave too late to catch up to the AI squadron before they reach France. Reflying that mission, the engine survives if I warm it all the way to 20 degrees and maintain +7 boost and 2650rpm.

[NineLine]

So a clean mission doesnt seem to have an issue. I have asked Reflected to send me that mission resaved and will test again.

Cleaning the plugs is as simple as increasing the power for a short period of time. (when I was a kid my Dad had a 69 Impala, he used to stomp on the gas occasionally, when my mom gave him a nasty look he said he was just cleaning the plugs  )

I also asked Nick "20C Oil is the critical one, coolant can be on or around 60, doesn't really matter. Oil is life... 40 for run up and takeoff"

Anyways I think there is something else at play right now so I will let you know. Thanks all.

 

[Pyrocumulous]

appreciate your efforts, the Spitfire is a gem to fly, and having two Reflected campaigns is the cherry on top!

[Rutch]

So glad the spit’s cooling system is getting some attention. Thank you. 

[grafspee]

10 hours ago, Pyrocumulous said:

No, I didn't clean the spark plugs, in fact, I was not aware that was possible. I do not see any mention in the Flight Manual or Chuck's Guide, and I am unable to locate a proper keybinding to accomplish that. How do I do it?

I generally let the engine oil warm to 20 degrees prior to taxiing, but even waiting until 15 degrees in Beware Beware Beware sortie 6 means you leave too late to catch up to the AI squadron before they reach France. Reflying that mission, the engine survives if I warm it all the way to 20 degrees and maintain +7 boost and 2650rpm.

It is mentioned in some manuals, but clearing sparkplugs was well known procedure so it may not be in all manuals.

How to clean sparkplugs in flight ? You just need to use higher power for every 20 min of low power cruise (example 2000rpm at 0 boost), also you can do spark plug cleaning before landing if you are planning to take off again with same plane.

Using climb power for couple minutes is enough to clear sparkplugs.

Back in ww2 times they used high lead fuels to get high octane ratings at low power setting lead buildup on sparkplugs, at higher power lead would burnout from sparkplugs, if we would have 150 fuel available this issue would be a nightmare, sparkplugs cleaning had to be done more frequent. 

Now, warbirds uses in most cases modern low lead fuels so this issue do not exist.

Edited December 24, 2022 by grafspee

[NineLine]

8 hours ago, Pyrocumulous said:

appreciate your efforts, the Spitfire is a gem to fly, and having two Reflected campaigns is the cherry on top!

Ok so I checked your track and then tried myself. I believe it comes down to just now warming the engine up to where it needs to be.

So this was your temps when you began to taxi:

I think the key here is your oil temps are just not good enough. But overall you are not very well warmed up.

I also noticed you warm up you let the engine idle. I, when its cold out, will bring the RPM up as much as 1500. This gets you warmer faster. As I said above, Nick said that the 20C oil temp is critical. The coolant is less as much, but doing it this way you should see coolant at least over 40 for taxi. 

Let me know if this works any better for you. 

[grafspee]

Don't forget to exercise engine before take off, this will bring temps even higher

Edited December 24, 2022 by grafspee

[Yo-Yo]

I performed 2 hours of flight at -4lb/1800...1900. Take off with 60C coolant. And every 15 minutes 15lb/3000 for 2-3 min. No problems. +1C at SL.

By the way, taxiing is the best way to warm the engine as you do not exceed 1000 +- rpm. As you are ready for engine check, the engine will be ready too.

[Art-J]

I guess the follow-up question is - is this plug fouling simulation implemented in other DCS warbirds and can cause similar engine problems when flying for longer periods at -4 lbs / 1900 RPM in Mustang or Mossie for example?

I know it's there in the Mustang when idling on the ground, but haven't tested long cruise flights at such low power settings.

[grafspee]

@Art-J I know that K-4 has this, at low power cruise you can notice speed drop and pitch of the prop decreasing.

[Rutch]

Hi all, thanks for the efforts here. Just a quick question. So if we want to fly at 0+ boost and 2000 RPM, we have to periodically clean the spark plugs by throttling up to 15+ boost and 3000RPM otherwise the engine dies?
 

The video below is from ‘The Longest Flight’ and at 0:27 you can see they are in the cruise at 8000 ft, 0+ boost and 2000 with the rad temp just above 60 degrees. 
 

 

In my experience the oil pressure goes through the roof and then the engine quits. the Rad temp goes below 40 which doesn’t seem right. Is this being looked at? Thank you and happy holidays all. R

[grafspee]

22 hours ago, Rutch said:

Hi all, thanks for the efforts here. Just a quick question. So if we want to fly at 0+ boost and 2000 RPM, we have to periodically clean the spark plugs by throttling up to 15+ boost and 3000RPM otherwise the engine dies?

If pilot ignore sparkplug fouling symptoms, when serious fouling occur, you can expect that some cylinders will miss fire and eventually power loss will be so significant that you will no longer be able to maintain alt. I don't know if this is modeled but when cylinder stops firing due to sparkplug fouling there is no way to fix that in flight only by replacing sparkplugs. 

Main effect of fouled sparkplugs is lost of power and this is very important thing during engine run up or engine test before take off,  if rpm of the engine are lower then expected or rpm drop on mags check is higher then expected this indicates problem with sparkplugs.

Screen shot from P-51 manual.

Edited December 25, 2022 by grafspee

[Gunfreak]

12 hours ago, Yo-Yo said:

I performed 2 hours of flight at -4lb/1800...1900. Take off with 60C coolant. And every 15 minutes 15lb/3000 for 2-3 min. No problems. +1C at SL.

By the way, taxiing is the best way to warm the engine as you do not exceed 1000 +- rpm. As you are ready for engine check, the engine will be ready too.

Every 15 minutes sounds very often. And doesn't 2-3 minutes at 15lb and 3000rpm kinda negative the reason for -4 boost and 1800rpm as 15lb and 3000rpm will use about as much fuel in 3 minutes as you do for 15 minutes at -4 and 1800.

[NineLine]

6 minutes ago, Gunfreak said:

Every 15 minutes sounds very often. And doesn't 2-3 minutes at 15lb and 3000rpm kinda negative the reason for -4 boost and 1800rpm as 15lb and 3000rpm will use about as much fuel in 3 minutes as you do for 15 minutes at -4 and 1800.

I think its a best practice type thing, its only needed when you are running very low power for long periods of time. I am also going to do more tests to see if there is any warning that the plugs are fouling, the track seemed very absolute... boom dead.

[grafspee]

12 hours ago, Gunfreak said:

Every 15 minutes sounds very often. And doesn't 2-3 minutes at 15lb and 3000rpm kinda negative the reason for -4 boost and 1800rpm as 15lb and 3000rpm will use about as much fuel in 3 minutes as you do for 15 minutes at -4 and 1800.

This is from P-51 manual

Definitely no need for 3 minutes of high power, imho 30sec of high power each 30min should be enough to prevent fouling.

BTW i love those drawings from US manuals  

The highest fouling happens at low power and rich mixture so, in case early P-51s don't know about Spitfires, you had 4 position mixture control like we have in P-47 now, if you go for cruise and forget to lean mixture you will get serious fouling with in maybe 20-30 min. But what i've read about this topic including 150 octane fuel test, roughness may appear after couple hour low power cruise and this was said about 150 octane fuel so with fully automatic mixtures in our Spitfire or P-51 and 130 octane fuel spark plug fouling should not be a big deal at all.

Take note that engine roughness is serious situation, when appears you are in trouble. 

The highest fouling appear to happen at idle engine speed while taxing or waiting for your turn to take off, a lot less in flight. 

I totally agree that running high power for 3 min each 15min of flight would defeat the purpose

1 min of max power each 30 min looks much more resonable. Since spitfire has no stop gate for emergency power, power setting for spark plugs clean up would be +15 boost or what ever max boost you can achieve at cruise alt and 3000rpm, it is obvious that 15boost won't be available if you cruise at 30k ft

It is very important to take off with high power but if you take off with low power which a lot Spitfire pilots do, it is recommended to increase to max power after take off to clean spark plugs from ground operations, fail to do so will contribute to faster fouling in cruise flight. 

Part of Spitfire pilot's notes

 

Edited December 25, 2022 by grafspee

[Yo-Yo]

9 hours ago, Gunfreak said:

Every 15 minutes sounds very often. And doesn't 2-3 minutes at 15lb and 3000rpm kinda negative the reason for -4 boost and 1800rpm as 15lb and 3000rpm will use about as much fuel in 3 minutes as you do for 15 minutes at -4 and 1800.

Yes, but 1) you fly longer distance at 3000/15 during these minutes, and
2) I forgot the manual directions, so, butter does not spoil porridge.

 

3) and it's better than to ignore spark plugs burning

[grafspee]

When ED introduce 150 octane fuel some day, proper warming up and ground operations like pre take off checks will be so important, other wise you won't fly anywhere

Edited December 25, 2022 by grafspee

[AndytotheD]

On 12/24/2022 at 5:50 AM, Rutch said:

Hi all, thanks for the efforts here. Just a quick question. So if we want to fly at 0+ boost and 2000 RPM, we have to periodically clean the spark plugs by throttling up to 15+ boost and 3000RPM otherwise the engine dies?
 

Discussion of the Longest Flight is not readily applicable to what our aircraft represents: modern aviation gasoline isn’t leaded anywhere near as heavily as WWII 100/130 fuel. 

[Rutch]

Ah I see your point @AndytotheD what I meant to point out was the radiator temperature staying above 60 at moderate power settings. 

[Rutch]

Also, found this on YouTube. The engine failure issue appears to be less of a thing:

 

[Art-J]

Well, correct o not, for the time being, good pre-takeoff warmup seems to be more important than sparkplug cleaning and increases chances of completing long, cold missions.

Combining conditions Pyrocumulous and Yo-Yo gave above, I just did a test flight on Caucasus map with 0 degrees SL temp (I don't own the Channel map, but that shouldn't matter). After startup immediately diluting oil to get the pressure below 120, then warming up to oil 50, coolant 60 for takeoff, then climbing to 20k, powering down to -4 lbs @ 1900 and flying around to see what would happen if I DIDN'T clean the plugs every now and then.

Well, temps went down and stabilized on oil ~52, coolant ~45, pressure ~100. After 40 minutes of flying... nothing happened, so I got bored and landed at the nearest airfield ;).

I'm not sure I would even try cleaning the plugs at full power, because that would bump oil pressure up to 150 easily and I'm a bit concerned about such high values after poor experiences with Thunderbolt and Anton (yes, I know, master bearing failure simulation and all that, but I wonder it "through the roof" oil pressures are not somewhat dangerous for DCS V-12 engines as well).

[grafspee]

@Art-J

At 52C oil temp, going for full power won't be an issue.

And clearing sparks every 30 min was just precaution, report which i paste in couple posts earlier states that engine roughness appear after couple hours of low power cruise.

Another thing is that sparkplugs had to be changed or cleared by ground crew eventually because high power plug clean wasn't cleaning them completely.

Edited December 30, 2022 by grafspee