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Complex Engine Management


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I feel it's way to easy to lock up the engine on the P-51 without any warning. Yes, you can glue your eyes to the temp gagues which is what real P-51 pilots did back in thier day. But it seems there is almost no warning audible until "clunk", and the prop/engine lock up. If you ever get the chance, check out A2A's P-51 for FSX. Your able to hear the bearings wear out, there is a loss of power, steam pours out the radiator, heavy engine smoke, maybe fire, and then the engine slowly grinds to a halt. Looks and sounds great!

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Can't really argue with you. That would be pretty awsome indeed. Although in IRL by the time smoke comes out not much chance the engine survived unscathed. (Or as we used to say If you can get the smoke back in she'll probably be OK again )

 

 

It did take me by surprise the 1st time the engine seized after the new patch haha. I did have to look at the Summary after the mission to see what happened.

I'd rather have a bottle in front of me than a frontal lobotomy and I've had both.

 

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You get those sounds and drop in performance, as the engine dies from overheating. If the engine is overstressed but remains cool enough it can still throw a rod = instant engine death.

 

Also as I've discovered recently running at too cool a temperature can be just as catastrophic.

 

Nate


Edited by Nate--IRL--
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Since 1.2.1 I've had my engine seize on me several times without obvious maltreatment, and then in the debriefing it says "engine shutdown" or sometimes "failure," followed by shutdown, so I really don't know what's going on.

 

I just finished a flight where I was flying for about 40 minutes before I got the engine failure. At the time, I was flying at max cruise MP and RPM and I had my oil and coolant radiator controls on automatic. I noticed that the oil temperature was above the green optimum band, but still had plenty of room before redline. I figured that was alright, because after all I would think the automatic controls would do something if it weren't. And there wasn't any combat involvement, so unanticipated presence of extraneous metal isn't a factor.

 

Aside from the oil temperature, everything was in the green, so I'm wondering if I should intervene when that oil temp is above the green (but below the red) and manually adjust the radiator or not. Thanks for any wisdom you guys can share.

 

EDIT: Oh, and I was flying at about 29,000 ft. Speed was probably around 300 mph, but I'm not certain.

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  • ED Team

Did you use 2700 46" rating all the time?

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Did you use 2700 46" rating all the time?

 

Yesterday, myself and flew a 65 minute training flight. I was using max constant power for pretty much all of this time and kept the engine well within the temperature and pressure limits. No adverse effects here and no damage as far as I know.


Edited by SkateZilla

Virtual Horsemen - Right Wing (P-51)  - 2008... 

Virtual Ultimate Fighters - Lead (P-47) - 2020...

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  • ED Team
Yesterday, myself and Fadec flew a 65 minute training flight. I was using max constant power for pretty much all of this time and kept the engine well within the temperature and pressure limits. No adverse effects here and no damage as far as I know.

 

Thanks!


Edited by Yo-Yo

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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How long can you run the engine on full power before it becomes a problem? Yesterday I was doing some dogfighting, and since Im not very good at this I was pretty much running max power all the time and I was flying for about 20 minutes, but didnt notice any problems with the engine.

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How long can you run the engine on full power before it becomes a problem? Yesterday I was doing some dogfighting, and since Im not very good at this I was pretty much running max power all the time and I was flying for about 20 minutes, but didnt notice any problems with the engine.

 

I suppose that would depend on all kinds of factors...

 

What your speed is, altitude and what the temps were like just prior to you going to full throttle. There's a lot of variables there

Virtual Horsemen - Right Wing (P-51)  - 2008... 

Virtual Ultimate Fighters - Lead (P-47) - 2020...

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Twice now I've been flying around at 32" and 2200 RPM at about 10,000 feet and had the engine seize after about 15-20 minutes of flight. Oil temp was in the green range.

 

I'm assuming we shouldn't do such "over-square" operation? Should our cruise power be more like 30" and 2400 RPM?

 

--NoJoe

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Yes, it seems you need to be rather cautious not to overboost the engine at low RPM. Take the power setting given on the plate in the pit as maximum boost pressures for the indicated RPM and you should be fine. As soon as you notice rough engine operation (indicated by shaking), immediately reduce MP or risk damage.

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Yes, it seems you need to be rather cautious not to overboost the engine at low RPM. Take the power setting given on the plate in the pit as maximum boost pressures for the indicated RPM and you should be fine. As soon as you notice rough engine operation (indicated by shaking), immediately reduce MP or risk damage.

 

Ahhh, thanks! :thumbup:

 

--NoJoe

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  • 4 months later...

Hi guys. My auto rads don't seem to want to open in 1.2.3 after having been in manual mode.

 

1) I was fighting the AI in instant action dogfight; noticed things were getting a bit warm in the oil & coolant depts and since the auto's weren't keeping up, manually opened them both fully & reduced RPM and MP to help. Eventually shot the AI down and noticed now things were a little too cool so slapped the rads back into auto & began my fast but gentle descent to the airfield. Low level doing 400+mph IAS I glanced at the temps, surprised to see both crawling towards redline beyond the green and then popped to external to see if the rads had opened.

 

Nada. Not a thing. Not even partially open. Is thera bug which means having gone manual the auto system is disabled?

 

2) Maybe I don't grasp the intricacies of how the Mustang rads work, but my understanding is that the doors were thermostaically controlled to provide the correct back pressure so that the heated air was forced from the opening at high velocity - high enough in fact that it more than cancelled the drag from the radiator housing.

 

It seems odd then that consistently I find that my engine is coming close to overheat but by going manual I can reduce it; shouldn't the auto function do that already? Surely if the automatic system is doing it's job I shouldn't be able to open the rads further?

 

Something seems a bit off.

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  • ED Team
Hi guys. My auto rads don't seem to want to open in 1.2.3 after having been in manual mode.

 

1) I was fighting the AI in instant action dogfight; noticed things were getting a bit warm in the oil & coolant depts and since the auto's weren't keeping up, manually opened them both fully & reduced RPM and MP to help. Eventually shot the AI down and noticed now things were a little too cool so slapped the rads back into auto & began my fast but gentle descent to the airfield. Low level doing 400+mph IAS I glanced at the temps, surprised to see both crawling towards redline beyond the green and then popped to external to see if the rads had opened.

 

Nada. Not a thing. Not even partially open. Is thera bug which means having gone manual the auto system is disabled?

 

2) Maybe I don't grasp the intricacies of how the Mustang rads work, but my understanding is that the doors were thermostaically controlled to provide the correct back pressure so that the heated air was forced from the opening at high velocity - high enough in fact that it more than cancelled the drag from the radiator housing.

 

It seems odd then that consistently I find that my engine is coming close to overheat but by going manual I can reduce it; shouldn't the auto function do that already? Surely if the automatic system is doing it's job I shouldn't be able to open the rads further?

 

Something seems a bit off.

 

Probably you were hit and automatics was gone. Regarding your observation I can only say that the temperature balance depends on scoop position, IAS and engine power. Automatic control is not of analog type but basically is wide hysteresis type. It has two thresholds. If the temperature exceeds the high level an actuator opens the scoop with constant velocity. If the temperature is within limits the scoop keeps its position. If the temperature is lower than low limit the scoop opens. The overall scoop travel time is about 15 and 20 s for oil and water radiators. Make your conclusions.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Probably you were hit and automatics was gone.

 

Hi Yo-Yo, thanks for your response. Negative on the battle damage front; the AI was never in a firing position.

 

Regarding your observation I can only say that the temperature balance depends on scoop position, IAS and engine power.

 

OK, this concept I understand; if I end up in prolonged climbing or turning manoeuvres I'm essentially flying in a worst case scenario situation; engine generating a lot of heat but not enough volume of cooling air at low airspeed being pushed through the rads.

 

Automatic control is not of analog type but basically is wide hysteresis type. It has two thresholds. If the temperature exceeds the high level an actuator opens the scoop with constant velocity. If the temperature is within limits the scoop keeps its position. If the temperature is lower than low limit the scoop opens. The overall scoop travel time is about 15 and 20 s for oil and water radiators.

 

Ah okay... so if the upper limit is reached the doors will start opening till they either go full open or at such time the temp falls below this datum point, say as an example 2/3rds open. If I reduce power and speed up and this causes the temp to fall below the lower limit the doors will start to close until they reach fully closed or until temperature rises above that lower limit.

 

My point is this; if I'm at 2800rpm and 50" and the gauges are tickling the redline, is this not at or beyond the upper threshold? And if so why haven't the rads gone full out already, if not on their way given the time scale you suggest?

 

If I can manually open the rads and get lowering temps in this situation. would it would not suggest that the upper threshold is too high?

 

Make your conclusions.

 

Trying man, bear with me - thanks for your patience!

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Hi Yo-Yo, thanks for your response. Negative on the battle damage front; the AI was never in a firing position.

 

 

 

OK, this concept I understand; if I end up in prolonged climbing or turning manoeuvres I'm essentially flying in a worst case scenario situation; engine generating a lot of heat but not enough volume of cooling air at low airspeed being pushed through the rads.

 

 

 

Ah okay... so if the upper limit is reached the doors will start opening till they either go full open or at such time the temp falls below this datum point, say as an example 2/3rds open. If I reduce power and speed up and this causes the temp to fall below the lower limit the doors will start to close until they reach fully closed or until temperature rises above that lower limit.

 

My point is this; if I'm at 2800rpm and 50" and the gauges are tickling the redline, is this not at or beyond the upper threshold? And if so why haven't the rads gone full out already, if not on their way given the time scale you suggest?

 

If I can manually open the rads and get lowering temps in this situation. would it would not suggest that the upper threshold is too high?

 

 

 

Trying man, bear with me - thanks for your patience!

 

As the system is not for exact keeping the exact temperature value, the actual temperature will be anywhere within the limits< and it depends on history and how fast you add power, etc, etc. THe normal situation is when the temperatures are below red ticks. At transition you can get it higher - it's normal. Imagine that you significantly reduce MP diving and make it slowly. The temperature will be catched near upper limit as the scoop almost completely closed. If you set MIL or WEP and begin to climb loosing speed the scoop can not be so fast to chase the increased power... so the temperature can escape throught the red tick. :) for a while.

 

And, by the way, the radiator drag will be zero or even negative only at high power ratings and high speed. The radiator installation works as a ram-jet. Compressing and heating then converged nozzle - it's a ram-jet.


Edited by Yo-Yo

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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  • 8 months later...

I have never seen this thread before... But after seeing it, i still agree that the engine is too sensitive to high throttle inputs. I think that destroying an engine after 15 minutes of flying is very strange (what woud hapen to real WWII pilots on those long dogfights where the engine was constantly at the top?).

 

And now referring to the engine high temperature failure, you should learn some more with the A2A P51D (sorry to mention other sims), you should see a lot of smoke and fire coming from the engine, and it should start slowing down instead of stopping instantly (this is impossible due to the huge amount of kinnetic energy stored on the engine)....

I think these are the only things that are missing to make the sim perfect

 

Peace

[sIGPIC][/sIGPIC]

 

"Your eyes only see what your mind is ready to comprehend"

 

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I have never seen this thread before... But after seeing it, i still agree that the engine is too sensitive to high throttle inputs. I think that destroying an engine after 15 minutes of flying is very strange (what woud hapen to real WWII pilots on those long dogfights where the engine was constantly at the top?).

 

And now referring to the engine high temperature failure, you should learn some more with the A2A P51D (sorry to mention other sims), you should see a lot of smoke and fire coming from the engine, and it should start slowing down instead of stopping instantly (this is impossible due to the huge amount of kinnetic energy stored on the engine)....

I think these are the only things that are missing to make the sim perfect

 

Peace

 

Most dogfights in WWII were very short. 15 minutes is an incredibly long time to dogfight. Only in the movies do pilots fight long drawn out engagements were they re-engage multiple times. In addition to that, the manufacturer of the engine specifically states that the engine should not be run at full for more than 15 minutes at a time. Wouldn't you think they are the authority on the subject?

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Most dogfights in WWII were very short. 15 minutes is an incredibly long time to dogfight. Only in the movies do pilots fight long drawn out engagements were they re-engage multiple times. In addition to that, the manufacturer of the engine specifically states that the engine should not be run at full for more than 15 minutes at a time. Wouldn't you think they are the authority on the subject?

 

Ok.... If it's the manufacturer who says so, i'm shutting up. :smilewink:

 

But there's still the engine explosion, which is very unrealistic...

Thanks for the heads up

:pilotfly:

[sIGPIC][/sIGPIC]

 

"Your eyes only see what your mind is ready to comprehend"

 

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Most dogfights in WWII were very short. 15 minutes is an incredibly long time to dogfight. Only in the movies do pilots fight long drawn out engagements were they re-engage multiple times. In addition to that, the manufacturer of the engine specifically states that the engine should not be run at full for more than 15 minutes at a time. Wouldn't you think they are the authority on the subject?

 

That's correct. Only very few engagements were that long. But probably some existed!

Nice one (P51 VS BF 109 - no time related): http://www.military.com/video/operations-and-strategy/second-world-war/dogfight-from-wwii/658292587001/

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  • 1 month later...

I'm sure boost limitation exceedences are not failure points in the Merlin as they are depicting in this sim. Max continuous is designated to meet TBO requirements for the engine and it's subsystems, it's not a point of failure and it is highly unlikely running at higher power is outside the automatic cooling system's parameters.

 

Max power limitations (wep or "mil") are points past which there is an increasing, and unacceptable probability of excessive engine wear, failure of various parts or loss of power, or coolant overtemp, or some combo etc.... it's not a single point of likely or certain complete failure. IMO making limitations failure points, then degrading the effectiveness of the coolant or oil systems to meet that point of failure, is not accurate.

 

I think under certain conditions of engine and operating environment the engine could overheat at wep, but not normally... To give an example of engine durability at high power, any use of wep in a Merlin (in US use) required an inspection for damage. 5 hours of logged wep required a complete engine teardown, even if there was no evident damage. If the engine is that durable, with repeated use of wep (even if they didn't exceed 5 min per use), I wouldn't expect lower power settings to routinely cause failure or coolant problems.

 

There are more obvious points of material failure I think, from combat damage etc, rumaway prop loss of fluids etc, reliability issues with certain parts, but I think wear and tear from high power and engine cooling capability needs to be further considered.

 

It may be going too far, but a Merlin overhaul shop like "51-Factory" could probably shed some light on what wears out, what fails, and why under what use. I think they have guys that have been overhauling Merlins in every conceivable condition for decades.

 

Anyway, just a few thoughts :) This sort of thing stands out as a minor issue IMO against what is a really impressive sim effort.


Edited by Barfly
Edited for clarity
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Here's a link to Merlin coolant system maintenance... some interesting details, may already be known by the developer:

 

http://www.51-factory.com/cooling_system_maintenance.pdf

 

Also, some notes about problems with cylinder head temperature increase with high time motors, due to "corrosion and scale in the coolant jackets inside the heads"... something you wouldn't see on a new motor:

 

http://www.51-factory.com/documentation.htm

 

Fascinating company... they have many cool pictures on their website of complete Merlins and parts in various conditions.


Edited by Barfly
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Barfly, that's very interesting. I recall the test on a (loaded? unloaded? I don't recall) Allison V1710 ended up running at WEP for a startlingly long period of time--I think it was ten continuous hours at WEP before it failed. I don't remember for sure, but it was nothing like fifteen minutes.

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There are accounts of pilots flying home at WEP and not even realizing it until they went to land.

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Associated with that are a lot of anecdotes on both sides about tired, worn out engines... No doubt to a large degree too much boost for too long. Certainly a lot of use variables come into play- some of the late war mustangs had 200+ hour overhaul intervals, mostly due to long missions at low power settings and relatively few engine start stop cycles. Some of that was also probably lessons learned and improved maintenance and operating procedures. Some MW50 equipped DBs lost cylinder pressure and performance from new engines getting run hard in relatively few hours by not complying with the factory prescribed breakin schedule (cant remember what it was... 5 - 15 hrs maybe?).

 

Of course late war German aircraft were expected to last an average of 15 hrs given attrition, so that was kind of a moot point, and many Mustangs and their pilots just cruised around and didn't see anything, never putting undue stress on the birds.

 

I'll keep digging for potentially useful info.


Edited by Barfly
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