Engine Managment help.

[Droning_On]

I think this is my lack of engine managment skill  rather than a bug

conditions:  winter and snowing, 0 deg C

After mission im low fuel over channel, heading back on low RPM (2000) to maximise range with oil pressure fine@100  Oil Temp @60+ degC & rad temp 40/50deg C  then this...............

            ["failure"] = "ENG0_ADVANCED_IGNITION_TIMING",
            ["failureDisplayName"] = "Engine #1 erroneous ignition timing induced damage",
            ["t"] = 2371.06,
            ["target"] = "SpitfireLFMkIX",
            ["targetMissionID"] = "116",
            ["target_coalition"] = 2,
            ["target_object_id"] = 16806656,
            ["target_unit_type"] = "SpitfireLFMkIX",
            ["target_ws_type1"] = 1,
            ["type"] = "failure",
            ["weapon"] = "Aw shoot.",
        },
        [960] = {
            ["failure"] = "ENG0_DAMAGED_BEYOND_REPAIR",
            ["failureDisplayName"] = "Engine #1 damaged beyond repair",
            ["t"] = 2371.06,
            ["target"] = "SpitfireLFMkIX",
            ["targetMissionID"] = "116",
            ["target_coalition"] = 2,
            ["target_object_id"] = 16806656,
            ["target_unit_type"] = "SpitfireLFMkIX",
            ["target_ws_type1"] = 1,
            ["type"] = "failure",
            ["weapon"] = "Aw shoot.",
        },

Am i too low RPM for weather ?? Help

[grafspee]

2000rpm but at what boost ?

 

[DD_Fenrir]

To my eye that looks like spark plug fouling; when running for long periods at low boost and RPM you need to periodically (every 15 minutes or so) punch up to combat power (2850 RPM, +12lb boost) for a minute to clean the plugs...

 

[Droning_On]

2 hours ago, grafspee said:

2000rpm but at what boost ?

 

Dont recall.... at 2000RPM i probably cranked the boost lever fully forward   

1 hour ago, DD_Fenrir said:

To my eye that looks like spark plug fouling; when running for long periods at low boost and RPM you need to periodically (every 15 minutes or so) punch up to combat power (2850 RPM, +12lb boost) for a minute to clean the plugs...

 

wow  didnt know that....  is that modeled ???  I was probaly only in low RPM for 5mins max hence why I thought it was weather related.

I was on the french side of the Channel... noticed fuel was on the lower tank so set course for home,, reduce RPM,  trimmed and after a very sort spell,,, dead stick.

Edited May 10, 2023 by Droning_On

[DD_Fenrir]

21 minutes ago, Droning_On said:

Dont recall.... at 2000RPM i probably cranked the boost lever fully forward   

 

Ah. Then it's more likely that you over-boosted the engine and this resulted in detonation. This could have caused the damage to the spark plus (ignition elements).

Remember if you open the throttle too wide at lower RPMs that it will result in detonation AKA knock.

At 1,800 RPM you shouldn't be above +2.75lb boost.

At 2,000 RPM you shouldn't be above +4.5lb boost.

At 2,400 RPM you shouldn't be above +6lb boost.

At 2,650 RPM you shouldn't be above +7lb boost.

At 2,850 RPM you shouldn't be above +12lb boost.

Anytime you go above +12lb boost you have to be at 3,000 RPM

 

21 minutes ago, Droning_On said:

wow  didnt know that....  is that modeled ???

Apparently, according to NineLine, it is.

Edited May 10, 2023 by DD_Fenrir

[grafspee]

Automatic boost regulator is preventing over boost but only at 3000 rpm, if you operate engine at lower rpm you need to respect engine limitation chart.

[Droning_On]

Damn... well that explains everything.

Thanks @DD_Fenrir& @grafspee

Going to test 

[Skewgear]

23 hours ago, DD_Fenrir said:

Remember if you open the throttle too wide at lower RPMs that it will result in detonation AKA knock.

At 1,800 RPM you shouldn't be above +2.75lb boost.

At 2,000 RPM you shouldn't be above +4.5lb boost.

At 2,400 RPM you shouldn't be above +6lb boost.

At 2,650 RPM you shouldn't be above +7lb boost.

At 2,850 RPM you shouldn't be above +12lb boost.

Anytime you go above +12lb boost you have to be at 3,000 RPM

 

Apparently, according to NineLine, it is.

 

Where do these numbers come from, out of interest?

You can certainly cruise at 2650rpm and more than +7lbs boost, the only reason for the pilot's notes giving +7lbs as max continuous is that's the highest boost setting before the mixture control veers rich of peak - it prolongs engine life.

Your statement not to use more than +12lbs boost unless you have 3,000rpm selected is strange. That's a slightly higher rpm setting than climb power. You can push our virtual Spitfire harder than that in perfect safety provided Ts and Ps stay within limits and the virtual pilot is careful about not running too hard for too long. Just keep the revs above 2,650rpm and the boost below +10lbs or so.

A new DCS player reading this might be confused into only using two thirds of the engine's maximum power output for fear of some catastrophic failure. That won't happen unless the engine is abused flat out for a prolonged period.

[DD_Fenrir]

I referenced this:

...these and the Mk.IX pilots notes.

Whilst I realise that the above are given for Mk.V airframes, the block of the Merlin from the 40 series to the 60 series was not much changed (primary modifications were supercharger related) and have assumed that these are relevant.

I made that the assumption that the max boost given for each RPM setting is the safe limit as for fuel economy it's revs that are the primary defining factor and you typically wish to fly at the maximum boost available at the a given RPM to maximise your airspeed (and minimise your flight time/exposure to risk in enemy airspace.)

I have not tested where the combination of RPM/boost causes detonation in the DCS Merlin, frankly my time is limited and I have better things to do when I do get a chance to play DCS than start a series of exhaustive trails and experiments, so I used these as a reasonable basis to go forward.

 

[DD_Fenrir]

20 minutes ago, Skewgear said:

Your statement not to use more than +12lbs boost unless you have 3,000rpm selected is strange. That's a slightly higher rpm setting than climb power. You can push our virtual Spitfire harder than that in perfect safety provided Ts and Ps stay within limits and the virtual pilot is careful about not running too hard for too long. Just keep the revs above 2,650rpm and the boost below +10lbs or so.

A new DCS player reading this might be confused into only using two thirds of the engine's maximum power output for fear of some catastrophic failure. That won't happen unless the engine is abused flat out for a prolonged period.

 

2850 @ +12 is Combat/Climb power and with a limit of 1 hour. Any RPM or boost setting over that is stressing the engine.

If RPM limits the maximum boost safely available would these figures be given in pilots notes? Why would +13, +15 or even +17 not be stipulated if that was 'safe' for limited periods.

Given that detonation cues in DCS can be masked by gunfire/buffet sounds (or just by being task saturated in a combat environment)and in previous years Merlins in Mustangs and Spits have been very unforgiving of over-boosting and suddenly seizing with very little warning, I assume the worst case; that is, those boost settings given are the maximum allowed for a given RPM setting to minimise chance of knock, and any boost setting above those should require an attendant increase in RPM to operate without risk of detonation.

[Droning_On]

5 hours ago, DD_Fenrir said:

Given that detonation cues in DCS can be masked by gunfire/buffet sounds (or just by being task saturated in a combat environment)and in previous years Merlins in Mustangs and Spits have been very unforgiving of over-boosting and suddenly seizing with very little warning, I assume the worst case; that is, those boost settings given are the maximum allowed for a given RPM setting to minimise chance of knock, and any boost setting above those should require an attendant increase in RPM to operate without risk of detonation.

Dont think ive ever heard detonation cues in DCS and probably wouldnt know one if I heard it tbh ..... on the ENG0_ADVANCED_IGNITION_TIMING it just stopped....   anyways following @DD_Fenrir boost guide I've not blown up any more Merlins 

Edited May 11, 2023 by Droning_On

[peachmonkey]

On 5/9/2023 at 8:41 PM, Droning_On said:

I think this is my lack of engine managment skill  rather than a bug

conditions:  winter and snowing, 0 deg C

After mission im low fuel over channel, heading back on low RPM (2000) to maximise range with oil pressure fine@100  Oil Temp @60+ degC & rad temp 40/50deg C  then this...............

            ["failure"] = "ENG0_ADVANCED_IGNITION_TIMING",
            ["failureDisplayName"] = "Engine #1 erroneous ignition timing induced damage",
            ["t"] = 2371.06,
            ["target"] = "SpitfireLFMkIX",
            ["targetMissionID"] = "116",
            ["target_coalition"] = 2,
            ["target_object_id"] = 16806656,
            ["target_unit_type"] = "SpitfireLFMkIX",
            ["target_ws_type1"] = 1,
            ["type"] = "failure",
            ["weapon"] = "Aw shoot.",
        },
        [960] = {
            ["failure"] = "ENG0_DAMAGED_BEYOND_REPAIR",
            ["failureDisplayName"] = "Engine #1 damaged beyond repair",
            ["t"] = 2371.06,
            ["target"] = "SpitfireLFMkIX",
            ["targetMissionID"] = "116",
            ["target_coalition"] = 2,
            ["target_object_id"] = 16806656,
            ["target_unit_type"] = "SpitfireLFMkIX",
            ["target_ws_type1"] = 1,
            ["type"] = "failure",
            ["weapon"] = "Aw shoot.",
        },

Am i too low RPM for weather ?? Help

hi, @Droning_On  out of curiosity and for my edification, where can I find these logs?

All I was able to find are the notes in SP briefing at the end of the mission that lists out all of the 'failures'. The logs you are showing are bit more in depth.

I you could point me to the location in files I would greatly appreciate it!

cheers.

nm, it's in debrief.log file..

Edited May 11, 2023 by peachmonkey

[grafspee]

This is fuel consumption chart for spitfire merlin 66

As you can see data for +7 boost is unavailable for rpm below 2400. So conclusion is simple, no one operate those engines at +7 boost at low rpm or at least no tests were performed at those power settings so +7 boost at rpm 2400 and lower was considered as unhealthy for engine.

Edited May 11, 2023 by grafspee

[Extranajero]

4 hours ago, Droning_On said:

Dont think ive ever heard detonation cues in DCS and probably wouldnt know one if I heard it tbh ..... on the ENG0_ADVANCED_IGNITION_TIMING it just stopped....   anyways following @DD_Fenrir boost guide I've not blown up any more Merlins 

 

I've never heard detonation in DCS either, I don't think there's a sound file for it.
Just to satisfy your curiosity it sounds like someone dropping glass marbles on concrete and it's unmistakeable once you've heard it.

[grafspee]

9 hours ago, Extranajero said:

I've never heard detonation in DCS either, I don't think there's a sound file for it.
Just to satisfy your curiosity it sounds like someone dropping glass marbles on concrete and it's unmistakeable once you've heard it.

Thing is that you won't hear knock in airplane, exhaust, propeller are just too loud. Fact that there is no sound for it in sound files proofs nothing.

Edited May 12, 2023 by grafspee

[Extranajero]

5 hours ago, grafspee said:

Thing is that you won't hear knock in airplane, exhaust, propeller are just too loud. Fact that there is no sound for it in sound files proofs nothing.

 

I couldn't say for sure, I'm quite experienced with classic racing engines, but none of those were attached to aeroplanes.

It'll be accompanied by stuff like rough running, power loss and black smoke though. All things that you can hear, feel or see.

Fuel mixture has an effect on the likelyhood of detonation, there is a bigger risk of it with the engine running lean.
 

[Art-J]

P-47 and 109 feature a cockpit vibration effect once you get really deep into the knock territory. No idea if "realistic", but a useful visual clue no doubt (for these who don't check the temps on instruments often enough). They're the only modules that have it, though.

[grafspee]

48 minutes ago, Art-J said:

P-47 and 109 feature a cockpit vibration effect once you get really deep into the knock territory. No idea if "realistic", but a useful visual clue no doubt (for these who don't check the temps on instruments often enough). They're the only modules that have it, though.

Both are capable of running engine at very high MAP w/o water injection so intense knock may happen. I can't tell that power loss due to knocking is modelled but engine damage due knocking is in sim for sure.

Thing like engine over heat during knock i can't tell is it in game or not.

Edited May 12, 2023 by grafspee