The Complex Engine Management Work Group

[Farky]

Ok, my 2 cents -

 

Lot of errors in "report". For example, engine modes from game are wrong. And I don't agree with proposed limits at all, they are very strange (COMBAT 43.5" MAP @ 2600 RPM for 30 minutes, really?).

 

To be perfectly honest, I don't like the idea of replacing time limits with another time limits. Time limits can work, I don't mind if there is time limit (with some randomness) hidden behind the curtain. But what is missing here are signs that pilot is overloading or hurting the engine. You should keep watching temperatures and pressures, just like in real life, not the clock.

 

One more thing - I am not co-author of this "report", please delete my name from it. Thanks.

[Venturi]

Second that, if changes are not made. Please remove my name as well.

[Venturi]

1. I do not agree that logistical considerations need to be taken into account regarding "limiting MAP", as you state in your report. No other aircraft in the sim operates this way. If anything, the extremely long TBO time of the Allison in comparison to other engines should argue that this is not a factor.

 

2. Your limits are off. 52" is NOT WER for the Allison.

 

3. You say nothing about removing the RPM limits from the modes.

 

4. You say nothing about adding in any of the detonation aspects I explained so laboriously, nor of overhauling the rest of the engine management system.

 

 

 

Basically, what this is, is a slight increase in the "emergency mode' timer, and nothing else. In fact, it also decreases continuous rating for MAP.

Edited August 21, 2017 by Venturi

[Venturi]

(for P-40E)

 

1. Overheat

   a. coolant (>125C) -- randomized timer from 1-5 min of overheat, leads to water gasket rupture and loss of cooling efficiency, loss of power

   b. oil (>95C) -- leads to immediate engine failure, randomized timer from 1-5min of overheat (major parts strength failure)

 

Coolant and oil temps should be more fluctuant than they are in game, and require tighter control of both heating and cooling.

 

2. Overspeed * (>3500rpm) --- leads to immediate engine failure at 10sec (major parts strength failure) 

 

3. Engine strength failure (1500hp or 56"/3000rpm) 

 

Add in timer with randomization for exceeding 5min at 56"/3000rpm (1500hp) strength rating, randomized time should be from additional 1min to 5min before immediate engine failure (major parts strength failure).

 

All modes below this power level are not limited, except as in 1, 2, and 4.

 

4. Detonation *,**

   a. air / fuel mixture too lean (must run auto rich at >38", maximum rich at >56")

   b. RPM / MP mismatch (per P38 chart, in general)

   c. absolute MP limit (60" MAP, based on compression ratio of 6.65:1 in V-1710 and 100/130oct fuel)

 

Add in detonation timers for:

 

4a, depending on variation from optimal mixture - if mix is too lean, progressive damage starting in 30sec, leading to engine failure in 2min at most, faster if at >40" - if mix is too rich, loss of engine power but no damage

4b, depending on how much higher MP is than it should be for the current RPM - progressive damage starting in 30sec, leading to engine failure in 2min at most

4c, in 15sec once exceeded (no randomization) - immediate engine failure

 

*No other RPM timers should be applied, besides those in 2 and 4b

**Detonation without damage can be apparent to the pilot with RPM fluctuations and increased vibration.

Edited August 21, 2017 by Venturi

[Venturi]

This is what I agree to ^

[216th_Lucas_From_Hell]

I'll go over it later today.

 

Quick answer to some things - might as well go without the names at all, added them in case anyone felt strong about it; can you get me a photo or pdf of an operations manual with the 56" rating? They'll surely require one to have this looked at; as previously agreed it's important to see how far they are in terms of in house detonation works and if they would welcome outside input on it before putting something anything together.

[Venturi]

This was the final rating for the V-1710-39, which agrees with 1500hp design capacity of the engine.

 

 

[216th_Lucas_From_Hell]

Addressed some concerns raised, edited the in game table (mine was from a user manual apparently, not an official source), added the 1944 limits as well, added 1944 limits to supporting material, changed suggestion of new limits based on it, names have been removed, added maximum dive RPM from three different sources (all agree on 3120) instead of the "over 3000 RPM" one in game, added suggestion to remove RPM from timer limit (oversight in the first version), added discussion thread to supporting material for both reference and to showcase different suggestions by members, generally fixed a lot of problems (forementioned and not) derived by late activation of caffeine ingested so my apologies.

 

Ok, my 2 cents -

 

Lot of errors in "report". For example, engine modes from game are wrong. And I don't agree with proposed limits at all, they are very strange (COMBAT 43.5" MAP @ 2600 RPM for 30 minutes, really?).

 

To be perfectly honest, I don't like the idea of replacing time limits with another time limits. Time limits can work, I don't mind if there is time limit (with some randomness) hidden behind the curtain. But what is missing here are signs that pilot is overloading or hurting the engine. You should keep watching temperatures and pressures, just like in real life, not the clock.

 

One more thing - I am not co-author of this "report", please delete my name from it. Thanks.

In game limits fixed, proposed limits fixed and linked directly to sources from 1941, 1943 and 1944.

 

I´m under the impression that the limits are not their way to go, but rather their way to create some consequence for engine operators without modelling too much under the hood. To be exact, until they get to model everything under the hood. Once DD120 points on detonation and finer fuel management have been added, then actually accurate rather than synthetic damage triggers can be implemented. In a way, these suggestions are to improve the placeholder rather than the final version.

 

 

(for P-40E)

 

1. Overheat

   a. coolant (>125C) -- randomized timer from 1-5 min of overheat, leads to water gasket rupture and loss of cooling efficiency, loss of power

   b. oil (>95C) -- leads to immediate engine failure, randomized timer from 1-5min of overheat (major parts strength failure)

 

Coolant and oil temps should be more fluctuant than they are in game, and require tighter control of both heating and cooling.

 

2. Overspeed * (>3500rpm) --- leads to immediate engine failure at 10sec (major parts strength failure) 

 

3. Engine strength failure (1500hp or 56"/3000rpm) 

 

Add in timer with randomization for exceeding 5min at 56"/3000rpm (1500hp) strength rating, randomized time should be from additional 1min to 5min before immediate engine failure (major parts strength failure).

 

All modes below this power level are not limited, except as in 1, 2, and 4.

 

4. Detonation *,**

   a. air / fuel mixture too lean (must run auto rich at >38", maximum rich at >56")

   b. RPM / MP mismatch (per P38 chart, in general)

   c. absolute MP limit (60" MAP, based on compression ratio of 6.65:1 in V-1710 and 100/130oct fuel)

 

Add in detonation timers for:

 

4a, depending on variation from optimal mixture - if mix is too lean, progressive damage starting in 30sec, leading to engine failure in 2min at most, faster if at >40" - if mix is too rich, loss of engine power but no damage

4b, depending on how much higher MP is than it should be for the current RPM - progressive damage starting in 30sec, leading to engine failure in 2min at most

4c, in 15sec once exceeded (no randomization) - immediate engine failure

 

*No other RPM timers should be applied, besides those in 2 and 4b

**Detonation without damage can be apparent to the pilot with RPM fluctuations and increased vibration.

 

1. Already in game

2. Added. Up until 3120 RPM was considered safe, so something between 3250 and 3500 RPM seems reasonable for absolute damage

3. Added.

4. Added, but might require additional work per DD120.

[Retnek]

...

To be perfectly honest, I don't like the idea of replacing time limits with another time limits. Time limits can work, I don't mind if there is time limit (with some randomness) hidden behind the curtain. But what is missing here are signs that pilot is overloading or hurting the engine. You should keep watching temperatures and pressures, just like in real life, not the clock.

...

+1 - well put! That's the difference between a complex game and a simulation aiming for realism as far as possible. No offence here, please. I would prefer not to have any complex engine damage, if it can't be done realistically.

 

Next to checking the gauges most important input would be changing the sound of the engine depending on it's state of attrition or damage. Same like we hear the changing of wind noise near critical flight conditions. In a lot of reports the pilots stated they were able to detect / analyse at least some problems by the ear. From a generally alarming "rough sound" to certain reasons like spark plugs or charger problems.

[JG5_Schuck]

+1 - well put! That's the difference between a complex game and a simulation aiming for realism as far as possible. No offence here, please. I would prefer not to have any complex engine damage, if it can't be done realistically.

 

Next to checking the gauges most important input would be changing the sound of the engine depending on it's state of attrition or damage. Same like we hear the changing of wind noise near critical flight conditions. In a lot of reports the pilots stated they were able to detect / analyse at least some problems by the ear. From a generally alarming "rough sound" to certain reasons like spark plugs or charger problems.

 

Exactly....... a point i've been making since BOS was launched.

 

The ONLY way to have realistic engine management in this game and turn it into a Simulator is to have a server side option to disable the Technochat, 

This would then force people to use the gauges...... and thus be as realistic as it can be within the limits of the game.

Whilst the technochat is there anything else is superfluous!  

[unreasonable]

Exactly....... a point i've been making since BOS was launched.

 

The ONLY way to have realistic engine management in this game and turn it into a Simulator is to have a server side option to disable the Technochat, 

This would then force people to use the gauges...... and thus be as realistic as it can be within the limits of the game.

Whilst the technochat is there anything else is superfluous!  

 

I never use technochat -  since I find the little bubbles or anything on the HUD -  break my illusion of being there.  I have seen a number of people saying the same.

 

So the CEM is as realistic as the programmers choose to make it, if you chose to fly that way. 

 

That is not to say that the server option you suggest is a bad idea: I have no opinion, since I do not MP anymore. Just that doing away with it is irrelevant for those of us who already prefer to do without. 

Edited August 22, 2017 by unreasonable

[xvii-Dietrich]

Brilliant thread this.  You all really know this topic well, and it is a joy to read and learn from the information presented herein.

 

 

The ONLY way to have realistic engine management in this game and turn it into a Simulator is to have a server side option to disable the Technochat, 

This would then force people to use the gauges...... and thus be as realistic as it can be within the limits of the game.

Whilst the technochat is there anything else is superfluous!  

 

Agreed completely.

 

I also agree with the comments on the audio. Hearing subtle variations in pitch, the occasional cough, or some roughness in the sound would be superb.

[216th_Lucas_From_Hell]

Dietrich, would you be able to verify something for me? On the LaGG-3, at 500m, try to set the maximum manifold pressure with about 30% of the RPM lever. Then do the opposite - 2600 RPM, whatever MAP reading you get with 30%. Finally, get both to 30% or so. I recall one of these combinations giving a rougher, deeper sound with RPM fluctuations (no damage though) but I can't recall which one was it. Is it still present in game? That would give us a clue on whether there is some infant modelling of detonation and, more importantly, safe RPM/MAP zones in game.

[Venturi]

The best indicator of roughness I have found modeled so far, is the Pe-2 s.87 RPM fluctuations when at max RPM for a time. There should be additional vibrations noted in the airframe possibly.

 

Sounds would be difficult, severe detonation usually has an *extremely* rapid jackhammer sound to it. It is from the explosion wavefront in each cylinder slapping the pistontop as it comes up, which slams the piston,

 

(via the clearances in the piston to cylinder / piston pin / connecting rod / crankshaft / crank journal all going from a few thousandths of an inch to zero in an incredibly short time)

 

right as it transitions to preignition and just before the engine fails. Otherwise not much sound difference.

 

What DOES change the pitch of sound, is the fuel air mixture. Too rich, and the engine sounds "fat" and gives a bit more "blubbery" combustion sound. You get dark soot from exhaust stacks. Too lean, and it sounds "thin". Extremely lean, and the engine will begin to "miss", some cylinders will not have enough fuel in the mix to explode on every revolution. NO smoke from this. Combine lean mix with high boost, and you paradoxically go from "thin" to detonation. Lean fuel air mixes actually are very susceptible to detonation, as the fuel itself prevents too-rapid explosions. Did you ever ask yourself why the mixture is said to go from "rich" to "lean"? The sound of the engine is why.

 

RoF actually also does this sound / exhaust smoke effect pretty well, with the caveat that it also gives exhaust smoke from lean mixes (incorrect). Of course, with a supercharged 1500hp V12 engine, the sounds are more intense than in RoF and the consequences of mismanagement (primarily from detonation due to too lean a mix, PLUS high boost) should be much more severe.

Edited August 22, 2017 by Venturi

[Venturi]

See attached re RPM overspeed.

[216th_Lucas_From_Hell]

Great stuff, could you give me the name/date of the book and, if possible, the source document they used for this?

[Venturi]

Whitney's Vees for Victory. You can look it up on Amazon.

 

The source document is "Allison 'firsts' as of 1942, from J.L. Goldthwaite files at Allison"

[216th_Lucas_From_Hell]

Perfect, thanks!

[JtD]

It should be mentioned that even these 4000+rpm weren't necessarily the absolutely limit, they way I understood it (at some point), was that these were still 'rated' rpm, with a reserve towards the actual mechanical limit.

 

4000rpm would significantly increase full throttle altitude for this engine, if supercharger and all auxiliary equipment (pumps, generators) could also take a 25% overspeed without falling apart or burning up. Auxiliaries would be important to consider for complex engine management, too.

[Venturi]

I certainly agree that the accessories would be spinning at similar overspeed and this would be an issue in reality. And that such RPM increases could also increase the critical altitude of the aircraft if able to be sustained. 

 

However, note that the duration of these RPM overspeeds was limited to 30 seconds. It says more that the engine could withstand severe overspeeds for short durations without damage, than it does about operational regimes.

 

I have seen anecdotal statements from pilots regarding their use of higher than maximal rated RPMs (in the order of 3200rpm) to obtain higher boost levels, and the tech sheet itself mentions that diving RPM was limited to 3120. Hazen additionally mentions the possible practice of engine overspeed to achieve higher maximum boost levels in his famous letter.

Edited August 25, 2017 by Venturi