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BF109 Engine Damage in boost/emergency mode

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22 hours ago, 1./JG2_Little_D said:

Hi guys,

Have you ever looked at the complete manuals of the 109 engines, doesent matters if E/F/G 109`s? And not only the ATA/rpm information? There it is clearly described, that one should fly from full pressure altitude with max power (max ATA, max RPM with autoprop). This also applies to the engines that have a 1 minute limit of ATA 1.42. Why? So that the turbocharger can even bring enough air into the combustion chamber, in order to be able to obtain a clean air/gas mixture at high altitudes. Yes ATA falls with the altitude, but the rpm`s remains !! The engine does not have the load and heat due to the changed mixture above the full pressure level as it would have on 500m or 3000m. So no problem with max power to fly above the full pressure level until the tank is empty and without damaging or overburdening the engine. 

 

regards

 

Little_D

 

 

 

 

Do you have images / references to this? Could use it as hard evidence to prove the point.

 

 

I am also surprised at some people in this thread literally disregarding logic to push their point along - multiple times people had to explain why their picture of a German document says something completely different to what they are claiming.

Edited by JaffaCake

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I guess the use of WEP was kind of self regulating. You could use it as long as you could keep temperature down. You always find numbers for temperatures in the flight manuals splitted in short duration and continiuous use.

So we know that the engine wont blow up after one minute WEP.
We know WEP wasnt used for long durations.

Maybe thats a solution?

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29 minutes ago, Grim said:

I guess the use of WEP was kind of self regulating. You could use it as long as you could keep temperature down. You always find numbers for temperatures in the flight manuals splitted in short duration and continiuous use.

So we know that the engine wont blow up after one minute WEP.
We know WEP wasnt used for long durations.

Maybe thats a solution?

 

 

This is the obvious outcome of WEPping continuously - 100% radiator that actually makes you less aerodynamically efficient than if you flew on combat with 15% rads....

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1 hour ago, Grim said:

I guess the use of WEP was kind of self regulating. You could use it as long as you could keep temperature down. You always find numbers for temperatures in the flight manuals splitted in short duration and continiuous use.

 

Temperature limits are typically given for water/coolant and oil temperatures, however, the critical points in the engine are typically exhaust valves and spark plug - metal items that protrude into the hot gas during the combustion process. Even with water and oil temperatures well inside the limits you can still damage/destroy/melt highly stressed parts inside the engine at too high power settings. An overheated spark plug for instance can cause pre-ignition, which can kill the cylinder, which can kill the engine. An overheated exhaust valve might not be able to properly close any more, reducing compression for that cylinder, reducing power output or just mess up the engine in different ways, it may also get stuck, in which case compression is pretty much completely gone and mechanical damage will occur. You'll also send unburned fuel into the exhausts which at some point will be burned off, and you'll be spilling the fuel over the engine for fatal consequences...

 

It's not reasonable to assume that a power setting like Notleistung, which was meant for shortest periods of time, for use in emergency situations, is to be run indefinitely, because the manual gives no time limit. It's no more reasonable than to assume the engine blows after one minute just because the manual gives a one minute time limit. We need to get rid of this entire line of argumentation, even if right now the game is modelled like this.

 

In the end it's physics and technology which matter, not words on paper.

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On 4/18/2018 at 9:21 AM, Gunsmith86 said:

Tryed it in the 109 G6

 

Test1: at 6000m you still get 1.42 ata the engine started to fail after 1min and 45 sec.

 

Test2: at 6000m 1.42 ata the engine started to fail after 1min and 15 sec. reduced power to 1.0 ata for 15min and than tryed again this time the damaged engine run for 1min and 58sec. on 1.42 ata before stopping completely

 

Test3: at 8000m with full power we get only about 1.16 ata the engine withstand this for 3min and 58 sec. before stopping.

 

The damage modell of the engine is at least more complex than some may belive because it never stops at the same time.

The bigest problem in the game with this limit is proberbly that you get no warning at all before the engine is damaged.

Also calling it a limit is proberbly wrong it should be seen more as a warranty from the engine manufacturer ( your engine will last at least 1min at 1.42 ata )

 

The biggest problem with this scenario in the sim, and it is true of many engines modeled, is that IRL, high RPMs are tolerable almost indefinitely, unlike high manifold pressures - as long as the RPMs are within the maximum engine design parameters. 

 

The bearing stress, or conrod stress, is a exponential function with increased RPM. Simplistically, it is this which causes failure due to excessive RPMs. Up to a certain point (varying by engine desgin) the engine can withstand the stress from revs, but beyond that certain point stresses go very quickly beyond design limits with increased RPM due to exponential increase.

 

Therefore quick failures are the way to model this rev limit, but ONLY when revs go above the maximum, which is usually indicated specifically in the manual. For instance, it was common for pilots to manually overrev the Allison, and the maximum RPM permissible for that engine, 3120rpm iirc, was ABOVE that rpm given by the maximum prop governor setting of 3000rpm. It is NOT proper to model engine failure due to 3000rpm and moderate boost pressures. Revs alone should NOT place the engine into “combat mode” and especially not “emergency mode”. 

 

However, on aircraft with combined controls such as the Bf109 or Fw190, revs and boosts are matched. In this situation things get more confusing, and it is important to differentiate when RPMs are going up, but not boost pressures. In the 8km altitude test above, maximum revs are exploding the engine very quickly (just as quickly as the other test at lower altitude with maximum boost), even when the boost pressures are below maximum permissible - and this should not be the case. There is one exception, with the Db601N - because the German engineers were trying to eek every bit of possible performance out of their design. But for 99% of the engines this is the way it is (because other engineers didn’t go into more complex altitude/combat regimes for the RPMs - and the Db601/5 series were long-stroke engines anyways, comparatively, which raised RPM-associated stresses even more anyways). Again, in aircraft engines, maximum revs do not have a “time limit”. Rather, due to the exponential increase of stress on engine parts with increased revs, there is a “do not exceed” rev limit. When you see a RPM and MP setting in a manual - associated with a time limit - the reason for the specified RPM is because that is the correct RPM for that MP to avoid problems like detonation or plug fouling, NOT because the revs by themselves are damaging to the engine. 

 

Whereas intracylinder temperature increase and subsequent detonation, is a linear function. The mathematics people will understand what I mean by comparing linear vs exponential increases. 

Edited by Venturi
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1 hour ago, Venturi said:

However, on aircraft with combined controls such as the Bf109 or Fw190, revs and boosts are matched. In this situation things get more confusing, and it is important to differentiate when RPMs are going up, but not boost pressures. In the 8km altitude test above, maximum revs are exploding the engine very quickly (just as quickly as the other test at lower altitude with maximum boost), even when the boost pressures are below maximum permissible - and this should not be the case. There is one exception, with the Db601N - because the German engineers were trying to eek every bit of possible performance out of their design. But for 99% of the engines this is the way it is (because other engineers didn’t go into more complex altitude/combat regimes for the RPMs - and the Db601/5 series were long-stroke engines anyways, comparatively, which raised RPM-associated stresses even more anyways). Again, in aircraft engines, maximum revs do not have a “time limit”. Rather, due to the exponential increase of stress on engine parts with increased revs, there is a “do not exceed” rev limit. When you see a RPM and MP setting in a manual - associated with a time limit - the reason for the specified RPM is because that is the correct RPM for that MP to avoid problems like detonation or plug fouling, NOT because the revs by themselves are damaging to the engine. 

 

Just to clear things up at no time in my test RPMs are going up they always stay at 2800 rpm! You cant run more  than this whitout takeing manual controll.

Updated my earlier post with RPMs.

Edited by Gunsmith86

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7 hours ago, JaffaCake said:

 

 

This is the obvious outcome of WEPping continuously - 100% radiator that actually makes you less aerodynamically efficient than if you flew on combat with 15% rads....

The cooling systems of most ww2 planes are not going to have a problem with WEP, or even higher boosts than WEP. The cooling system was not designed with such a small tolerance. When mustang units switched to 150 octane 72/75in of boost (a gain to 200bhp) test results showed massive gains in both level speed and climb rate. It takes alot of time to test both of those, meaning you would have to run WEP for long periods. The business of the rads being inadequate is only relevant for badly designed cooling (yak1) or games like War Thunder or il2 46. Where you might see a deficiency is in the most extreme maneuvers only. You wouldn't have any issue if just flying in straight lines or doing turning fights. Where you might see issues are something like a 50deg of flaps 109mph turn for 5 minutes or something. Or repeated hammerheads at WEP. In general flight you would not see a problem. 

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Oil temps are more indicative of engine load / power output. However, in water/glycol cooled engines, the oil and water cooling systems interchange heat. This means that the oil temp might rise, but it will be buffered by the rise in water temperature. Because water has a much higher specific heat (defined as the thermal energy required to raise a cubic cm of the substance 1deg K) than oil, that means that water can absorb much of the heat that the oil does, given a little time for the heat exchange to take place.

 

On the other hand, air-cooled engines do not have water (with its high specific heat) to buffer the oil temperature (or the cylinder heads' temps - which are made of steel, which also has a low specific heat compared to water). The advantage of an air-cooled engine is that although the material which dissipates most of the heat (the engine heads and block themselves - made of steel or aluminum) has a low specific heat, its thermal conductance is extremely high. That means that the engine block as a whole absorbs much of the heat originally concentrated in the cylinder heads, and it does so quickly. This entire mass of the engine block (some several hundreds of kilos) then participates in heat exchange with the air. So although steel has a low specific heat compared to water, there is much more of it in terms of MASS, participating in heat exchange, when compared to the mass of the exchange medium in a water-cooled engine (really only the coolant itself which might be a hundred to two hundred liters of coolant approximately).

 

So the bottom line is that the first thing to overheat on both an air cooled and water cooled engine would be the oil, but given enough airflow and enough time to equilibrate, the water or cylinder heads temps will be the main issue.

Edited by Venturi

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First problem is the developers did not include any working coefficient. If manual say 1 minute it means the engine - for sure - would be extensively tested and proved to withstand 5 minutes and return home.

If engine would mean fatally explode after 1 minute manual would state 20 sec. Or completely forbidden.

 

Second problem is even after exceeds the work regime there would be gradual wear with many signs. In the game everything is perfect, than there is just one random second and you can jump, the engine is completely destroyed. There is not how combustion engine dies.

 

We just need to wait for some more complex engine model being implemented, not random failure after arbitrary time without any working coefficiency.

 

Cheers;)

Edited by bies
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1 hour ago, bies said:

First problem is the developers did not include any working coefficient. If manual say 1 minute it means the engine - for sure - would be extensively tested and proved to withstand 5 minutes and return home.

If engine would mean fatally explode after 1 minute manual would state 20 sec. Or completely forbidden.

 

Second problem is even after exceeds the work regime there would be gradual wear with many signs. In the game everything is perfect, than there is just one random second and you can jump, the engine is completely destroyed. There is not how combustion engine dies.

 

We just need to wait for some more complex engine model being implemented, not random failure after arbitrary time without any working coefficiency.

 

Cheers;)

Of course that is the best case scenario.

Until then we need the same standards for every plane. That is what the manual states. And again, the manual simply doesn’t say 1 minute.

Edited by =EXPEND=SchwarzeDreizehn
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It's all about working coefficient. Every engine of the same type is different.
If real engine would be expected to blow up completely just after 1 minute it means another one withstand  1 min 20 seconds  when next just  40 seconds. So if engine would be expected to really stop/explode after 1 minute nobody would even consider allowing more than 20 seconds because 30% of the engines would stop in the middle of the air in the allowed limit!
Next you have to include some engines are new, some are wear. And if you put 1 minute in manual you have to guarantee this time + working coefficient for the most wear ones allowed to fly.
To allow 1 minute they needed to test the engines and prove they can go about 5 minutes before the failure.
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How are we back to discussing the ticking engine go boom timer. Good Lord people. The engine limits were not written with engine go boom in mind. It has nothing to do with it, so discussing at what time the the engine go boom is a non sequitur.

 

I agree with the concept of working coefficient, but you guys need to apply this to all thoughts regarding a boom time. Nobody who is sane would approve a engine power setting that is within minutes of engine destruction, for the precise reasons you guys are pointing out regarding 1 min. 

 

There is good reason that we do not have a SINGLE document that lists a engine go boom time, and all the evidence we do have is for extremely long test runs (like the 7.5 hour ones I linked for the 38, 47, and 51). 

 

That reason, is that engine go boom is not a time related concern at officially approved boost ratings. The time restrictions are there EXCLUSIVELY to ensure a certain operational life of the engine. That life, depending on the plane and conditions, is something like 50-200 hours. 

 

That is why it is so bogus for this conversation to revolve around "what time" should we implement. The only reason we are discussing TIME, is because for some reasons we cant extrude our brains out of the manual residue. 

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15 hours ago, Fumes said:

How are we back to discussing the ticking engine go boom timer. Good Lord people. The engine limits were not written with engine go boom in mind. It has nothing to do with it, so discussing at what time the the engine go boom is a non sequitur.

 

I agree with the concept of working coefficient, but you guys need to apply this to all thoughts regarding a boom time. Nobody who is sane would approve a engine power setting that is within minutes of engine destruction, for the precise reasons you guys are pointing out regarding 1 min. 

 

There is good reason that we do not have a SINGLE document that lists a engine go boom time, and all the evidence we do have is for extremely long test runs (like the 7.5 hour ones I linked for the 38, 47, and 51). 

 

That reason, is that engine go boom is not a time related concern at officially approved boost ratings. The time restrictions are there EXCLUSIVELY to ensure a certain operational life of the engine. That life, depending on the plane and conditions, is something like 50-200 hours. 

 

That is why it is so bogus for this conversation to revolve around "what time" should we implement. The only reason we are discussing TIME, is because for some reasons we cant extrude our brains out of the manual residue. 

I very much agree with you Fumes, it is so logical and I suspect that 'Spock' would be smiling at this human failing (artificial engine timer boom thing) and 'Scotty' would have nothing to do with it, LOL.  I think 'Spock' and 'Scotty' would be in total agreement.

 

Happy landings,

 

Talisman 

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And the developers disagree totally so there's no chance of seeing this in game. So what's the point? 

 

Changing the engine model so that it's more advanced and covers detonation and several other things we don't see in game now, that's a possibility though.

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If the correction proposal is made right and justified by proof, Devs should listen. Otherwise, the entire complaint process is useless.

Edited by VesseL

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I think IL2 , Han ... Developers are correct about the argument  of 1 minute of emergency power .

 

we have another answer in YouTube video  obout this interview :

 

But obviously is not a test  answer obout the maximum emergency power at 1.42   ata time limit . That could objectly clarify at all . 

 

For this plane is always at 1.3 ata like the Bf 109 G2 .

 
 
Ra man
We are from the forum of I2Sturmovick BOS Thanks waiting for answer . RAY-EU forum founder member.
 
 
 
 
III/JG 52 Virtual
As far as we know the flugmuseum Messerschmitt does not use the "emergency power" in his BF-109´s for conservation reason. The use of "emergency power" decreases the TBO (Time Between Overhault) and the engine´s live, that is very important for these unique and rare airplanes. This issue was mentioned by Volker Bau in the minute 7:24 of our video interview, he stated that only uses a maximum power of 1.3 ATA, and this match with "Climb and Combat power" (steig- und Kampfleistung) in the Bf-109G operation manual.
As far as we know, the time of one minute of "maximun continous use" in DB-605, at "Take-off & emergency power" are "preventive recommendations" for prevent; material stress, excessive bearings wear, oil or water overheating, etc and prevent for in-flight engine destruccition.. but after a resting time working at low power settings, which restauring the fluids temperature, oil presure, etc. The engine can be used a few times more at "Take-off & emergency power", always for a minute, and it would be replaced for inspecction and overhault, after landing.
Today DB-605 engine replacement and overhault is very expensive and difficult because lack of spare parts, certified manufacturer, workshops, etc
Mostrar menos
 
 
Edited by RAY-EU
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11 hours ago, RAY-EU said:

As far as we know the flugmuseum Messerschmitt does not use the "emergency power" in his BF-109´s for conservation reason. The use of "emergency power" decreases the TBO (Time Between Overhault) and the engine´s live, that is very important for these unique and rare airplanes.

 

How can this be interpreted like a 1 min blowup timer, seriously. He clearly said "for conservation reason" and "The use of emergency power decreases the TBO and engines live". This is what we all already now since forever. No words about a blowup timer or anything near like that. Notleistung decreases engine live, no body would argue that fact. I mean all engines degrade even the russian ones in real life. Yeah, even M105-PF and Ash82F/FNs, even when there is no time limit in the manuals. If you try to simulate engine wear, do it the same for all engines. This 1 minute blowup timer is ridiculous and has nothing to do with real life. 

 

11 hours ago, RAY-EU said:

in DB-605, at "Take-off & emergency power" are "preventive recommendations" for prevent; material stress, excessive bearings wear, oil or water overheating, etc and prevent for in-flight engine destruccition

 

Nothing about that more then one minute blows up the engine. Remember, these guys from Messerschmitt Museum dont use Notlesitung to prevent uneccesary engine wear and not out of fear to blowup the engine after 61 seconds. They dont need Notleistung, they even dont need Kampfleistung for everything but for takeoff maybe. And i wouldnt be surpreised when they only use Dauerleistung to prevent engine life even further. Because they need to pay for engine overhaul big price because there are just a few flightready planes worldwide and people and replacement parts are rare.

 

Do you guys think that a Yak1b for example would be flown at 1.41ata at 2700rpm all day long today? Come on!

Edited by Ishtaru
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On 4/22/2018 at 8:23 PM, VesseL said:

 and justified by proof, 

 

Alas, after wading through the rhetoric there's not really much of that to be found in this thread.........  

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3 hours ago, Ishtaru said:

 

 

 

Do you guys think that a Yak1b for example would be flown at 1.41ata at 2700rpm all day long today? Come on!

 

It is almost like you did not read or digest a single thing said in the other thread by JTD that you recently commented on.... Where it explains that klimov is producing same power as DB at 1.15 ATA, engines are not the same and should not be directly compared, it is more complicated than you want to understand 

 

Cheers, Dakpilot 

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[edited]

 

20 hours ago, Dakpilot said:

it is more complicated than you want to understand 

 

I think this should be the epitaph for this whole thread.  Interesting post by RAY-EU.  

Edited by SYN_Haashashin

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1 minute ago, Dakpilot said:

It is almost like you did not read or digest a single thing said in the other thread by JTD that you recently commented on.... Where it explains that klimov is producing same power as DB at 1.15 ATA, engines are not the same and should not be directly compared, it is more complicated than you want to understand 

 

I understand and accept what JTD said but i just dont believe that klimovs are not at the absolut maximum. Read again what i said.

 

3 hours ago, Ishtaru said:

Do you guys think that a Yak1b for example would be flown at 1.41ata at 2700rpm all day long today? Come on!

 

So you think that a Yak1b with a M105PF engine, would be flown at 1.41ata @2700rpm all day long in real life TODAY? Like on an airshow for example?

 

You just didnt understand in what context my rethoric question was made. Sorry for you. Read again the post i replied to! And the fact that we cant compare the DB605 with M105PF has nothing to do with what i mean.

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21 minutes ago, Ishtaru said:

You just didnt understand in what context my rethoric question was made. 

 

:cool:

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Well , the last challenge difficult  chance. We could ask Erich Brunotte pilot of WW2 that flight in combat 3 kinds of Bf 109 and Fw190 A4 , A6 A8 . How you see in his biography historic book of the lutwaffe of technic . About :

The  1 minute time limit emergency power at ata 1.42 . ?

In the youtube video of The Interview I published of Volker Bau , Erich Brunotte appears at the beginning saying hello at the technical pilot of the Airbus of the historic Bf109 as a Consultant.

Many Thanks to III/JG52_Otto-I- that has give us all that information who we are in contact.

And Here is his webside biography : 

 

http://video.flyingheritage.com/v/116079427/feldwebel-erich-brunotte.htm

Edited by RAY-EU

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On 4/20/2018 at 3:21 AM, Grim said:

The main problem that prevented WEP in the earlier 109s was temperatur related bubbles in the oil film.

 

The main problem was detonation, which will ruin bearings and erode/burn through piston tops. It is why you do not see nearly any German aircraft rngine using above 1.4 Ata pressures until mw50 was released for use, while even early war Allisons and Merlins used more. Why? Because they had access to 100 octane, or higher, fuels. Strategic material shortages have real impacts. 

 

It is extremely difficult to differentiate main bearing wear due to detonation, versus due to oil pump deficiencies. Especially when you want it to be the other guy’s fault for all the ruined engines, and double especially while operating DB gmbh in Nazi germany during wartime. 

Edited by Venturi

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6 hours ago, Venturi said:

 

The main problem was detonation, which will ruin bearings and erode/burn through piston tops.

 

No it was not. http://kurfurst.org/Engine/Boostclearances/DB605A_GLmeeting_September1943.html

 

It is why you do not see nearly any German aircraft rngine using above 1.4 Ata pressures until mw50 was released for use, while even early war Allisons and Merlins used more. Why? Because they had access to 100 octane, or higher, fuels. Strategic material shortages have real impacts.

 

Except the Germans were producing large quantities of synthetic 100 octane (and later 150 grade) fuel since the beginning of the war of course. High octane performance numbers are a result of additives to the base stock fuel. Synthethic plants were already producing a large volume of those additives as a side-product.

 

Part of the reason why Allisons and Merlins were running on higher manifold pressures was their limited swept volumes - about 27 liters vs. the typical cc. 35 liters used on German engines. If an engine has lower swept volume, it need to use either higher RPM or more supercharging to keep up the pace with the big bore engine.

 

And its not particularly difficult to do, since supercharged engines already have plenty of surprus pressure to be tapped, however, in order to enable higher manifold pressures withot detonation, both Merlins and Allisons had to be kept down at relatively low compression ratios (6:1), resulting on low specific effiency and at the expense of high altitude performance. Hence why the Merlin for example always run at high manifold pressures, even on 87 octane fuel it rant at almost 6+ lbs/sq. inch, which is about 1.6-1.7 ata IIRC.

 

It is extremely difficult to differentiate main bearing wear due to detonation, versus due to oil pump deficiencies. Especially when you want it to be the other guy’s fault for all the ruined engines, and double especially while operating DB gmbh in Nazi germany during wartime.

 

German engineers found it pretty easy to differentiate though, for their discussions about the DB 605 issues are always revolving around lubrication issues and not ignition issues. 

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Can we get back on topic with this?

 

What we have right now :

- Different aircraft have different "times" specified in the manuals that devs referenced

- By current design the engine blows up after such time is exceeded, with a little more complexity (i.e. if manifold pressure is lower at altitude it would extend the time)

- Currently all models of bf109 have 1 minute emergency time

 

What is being argued :

- Not all b109 engines were the same, as far as I could gather:

---- bf109-e7 engine had 1 minute emergency boost time in the manual

---- bf109f-onwards had either :

--------- Completely banned emergency power

--------- Unspecified duration of emergency power after "reinforced cylinder heads" modification to the engine

--------------- With some indications that the time was either 5 minutes ( factory testing ), or 3 minutes ( picture of 109 dashboard with such mark ).

 

 

Currently we, again, do not have any proof provided that says that 1-minute emergency limit was present AFTER cylinder head reinforcement (Edit: or before reinforcement - it was banned then completely). Bear in mind that pilots themsleves may have put different anecdotal limits on these engine modes to conserve the engine resource, especially later in the war for LW side. (which is why IMO 5 minute factory test is more reliable than the 3 minute mark picture).

 

 

Edit: in regard of bf109f-onwards I mean 1.42 ata when I mention "emergency".

Edited by JaffaCake
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9 minutes ago, JaffaCake said:

Currently we, again, do not have any proof provided that says that 1-minute emergency limit was present AFTER cylinder head reinforcement.

 

No wrong. There is no evidence of a 1 minute emergency limit for all F and Gs period.

It is either banned or allowed.

 

The argument with the 3 minute markings and 5 minute break in, is simply adding to the fact that the 1 minute is absolutely wrong. They are by no means proof that the engine would break after 3 or 5 minutes.

Edited by =EXPEND=SchwarzeDreizehn
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1 hour ago, VO101Kurfurst said:

Except the Germans were producing large quantities of synthetic 100 octane (and later 150 grade) fuel since the beginning of the war of course.

 

C3 fuel was of limited supply late in the BoB. Was used by some Bf110s and a few Bf109s. Late war C3 was lucky if it had a PN of 140.

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Since we sort of got spun around a bit, Ill reiterate my desire for the game:

 

-Emergency power in current and future BOX titles should be unlimited without damage (this does not just apply to German planes). Exceptions to this rule would have to be supported by some specific evidence. Airplanes that require injection of some form would be limited to however long their injection mixture tank lasts. 

 

-1.42ata in BOX should be implemented on a case by case basis. F model should be unlimited. G serious should have 1.42ata as a modification that can be controlled by the scenario designer depending on the intended date span of the scenario. 

 

-If possible, complex engine failures should be added at a future date. Any added failures should be due to pilot error of some kind. No RNG. No Timers. Limits should still be removed in the mean time since WEP usage will still be unlimited for all intensive purposes even if we do get complex engine management. 

 

-Power settings of planes without MP regulators like the P-40 will have to work on some other system entirely. An effort will need to be made to determine the max safe power and implement engine damage above that. If a precise estimate can not be made some semi-arbitrary but reasonable power setting will have to be established.  

 

 

 

 

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10 hours ago, Venturi said:

 

The main problem was detonation, which will ruin bearings and erode/burn through piston tops. It is why you do not see nearly any German aircraft rngine using above 1.4 Ata pressures until mw50 was released for use, while even early war Allisons and Merlins used more. Why? Because they had access to 100 octane, or higher, fuels. Strategic material shortages have real impacts. 

 

It is extremely difficult to differentiate main bearing wear due to detonation, versus due to oil pump deficiencies. Especially when you want it to be the other guy’s fault for all the ruined engines, and double especially while operating DB gmbh in Nazi germany during wartime. 


I read that the detonation problem was also solved when they changed the ignation point for 2°. But it seemed that the detonation wear was the smaller problem.

@WEP timing

I heard a interview where a LW Pilot referred to the G-6 WEP. They where allowed to use it for 5 minutes because you head to revise the engine if you would use it any longer.
In actual combat he never used it longer then 1 minute. ..but he didnt explained why.

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5 hours ago, Grim said:

In actual combat he never used it longer then 1 minute. ..but he didnt explained why.

 

Maybe he didnt need to because aircombat, how we experience it ingame, has nothing to do with real life aircombat back then i guess or that he just didnt remember using it longer. Aircombat is terrifying, So i wouldnt blame him for forgetting how long he used what setting in combat. And a part from the fact that engines degrade over time, you have much more to worry about, not just engine wear at higher powersettings. Fuel consumption raises, heat produced increases, oil can get to hot, cooling liquid can vaporize if to hot and im sure there are much more things happening which worsens engine wear. So a real pilot would use Notleistung only when really needed and not just to cruise around but infight he will use it as long as he needs to and the observable parameters are within limits.

 

How did he know that he never exceeded the 1 minute self destruction timer? Did he had to use a stopwatch or did he count in his head? Thats pretty much to be aware of while being in a combat situation. Maybe he only talked about non combat situations which happen more often then actual aircombat? Only then the strict 1 minute timer would make any sense, to not stress the engine unnecessary while not in combat and guarantee max perfromance in an actual emergency situation. Which aircombat is when you ask me. They didnt had technochat like we have. ;)

 

16 hours ago, Venturi said:

The main problem was detonation, which will ruin bearings and erode/burn through piston tops.

 

If detonation was the limiting factor. Why should any sane engineer allow a powersetting where this can happen after just 1 minute without any possibility to recognize that a failure start to happen before the engine blows up? I dont understand. One minute is so short, it makes no sense to give performance numbers for such a powersetting like climb and topseed when it is so limited, that you even cant reach that topspeed in that one minute.

 

I mean, try to estimate one minute while playing soccer or doing something which is exciting and occupay your thoughts. You will fail, one minute is just to short for anything. Even for Sex it is to short and now try to estimate how long you could hold it. Was it exactly one minute or was it infact just 20 secs because time is time but it depends on the situation how you percieve time yourself. Time seems to be shorten when doing something exciting and slows down when you do something boring. Everyone should experienced that. So how to be sure that you be in that one minute timeframe while doing aircombat in real life where your brain pumps out adrenalin and you are terrified.

 

Im not arguing to get time limits changed, i gave up on that. Devs obviously think the same as most of the constant defnders of blowup timers. So this system will stay, maybe forever who knows. I just want to point out how little sense it makes to alow such short timers when it comes to guarnateed engine blowups (detonation) and that it makes no sense to allow such a setting when it does more harm then it is of any use. Even the 3 minutes in the 190s are very short but it is at least kind of useable and helps here and there. And if detonation caused through low octane fuel is the reason for such short timers. Why does the 190 also has short timers with C3 fuel then? So detonation happens just 2 minutes later in high octane fuel but the Ash82FN, which is comparable to the BMW(?), dont have any detonation issues and can run at higher performance forever where BMW have to be time limited even at lower powersettings of 1.3ata. There is no time limit at 1.36ata for the Ash82FN and the cooling efficiency is superb so no drag at even the highest powersettings of 1.60ata even at summer temps.

Edited by Ishtaru
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17 hours ago, VO101Kurfurst said:

 

No it was not. http://kurfurst.org/Engine/Boostclearances/DB605A_GLmeeting_September1943.html

 

Goring had about as much technical knowledge of engines as your average bureaucrat. He was a WW1 flyer and an amble imbiber of delicacies, not an engineer. It would have been very easy for him to be duped. As I said before, you do not get burnt through pistons from oiling issues.

 

Except the Germans were producing large quantities of synthetic 100 octane (and later 150 grade) fuel since the beginning of the war of course. High octane performance numbers are a result of additives to the base stock fuel. Synthethic plants were already producing a large volume of those additives as a side-product.

 

TEL was available, (the Germans used other substances too) but you can only add so much before plug fouling. If your base fuel is much lower in octane content, you still can't reach the numbers that a better octane fuel will with the same amount of TEL.

 

Part of the reason why Allisons and Merlins were running on higher manifold pressures was their limited swept volumes - about 27 liters vs. the typical cc. 35 liters used on German engines. If an engine has lower swept volume, it need to use either higher RPM or more supercharging to keep up the pace with the big bore engine.

 

Thanks for enlightening me. https://ww2aircraft.net/forum/threads/which-country-designed-the-best-engines-for-wwii.8253/page-14#post-1285556

 

And its not particularly difficult to do, since supercharged engines already have plenty of surprus pressure to be tapped, (really? at what altitude hmm?) however, in order to enable higher manifold pressures withot detonation, both Merlins and Allisons had to be kept down at relatively low compression ratios (6:1), resulting on low specific effiency and at the expense of high altitude performance. 

 

That's not the mechanism of CR to MP tradeoffs. Lower compression ratios give the ability to cram more actual chemical REACTANT into the cylinder via higher boost. Compression stroke increases the efficiency of the mix already there. Actually the lower compression ratio'd engines make MORE power, due to higher boost levels allowed, assuming you have the fuel octane to handle it. If you don't, then better up the compression ratio. A higher compression ratio also increases performance at idle, and allows more valve overlap, among other things. All of which may play into the automated engine management system of the DB601/5 series.

 

 

 

50/50 fuel production, at most 60/40 fuel production by 1944 to 1945, does not sound like they had a "surplus" of high octane fuel to go around, especially in the east. Especially since ALL BMW 801D's had to have C3...

 

https://ww2aircraft.net/forum/threads/german-c3-fuel-production-and-consumption-during-1944-1945.22499/#post-614541

 

 

7 hours ago, Ishtaru said:

If detonation was the limiting factor. Why should any sane engineer allow a powersetting where this can happen after just 1 minute without any possibility to recognize that a failure start to happen before the engine blows up? I dont understand. One minute is so short, it makes no sense to give performance numbers for such a powersetting like climb and topseed when it is so limited, that you even cant reach that topspeed in that one minute.

 

Because they miscalculated, and were pushing the absolute limit of the engines. Pilots don't always follow the rules, especially in combat. You give a pilot a rule, and he may follow it, or not, in the heat of battle. It is the same reason the Allison could overboost to well over 60" in the right conditions, although the maximum rated was much lower.

 

The DB601/5 series has a history of pursuing maximum performance possible given the strategic limitations the 109 fighter was expected to fulfill (cheap, high performance, easily maintained). It is the same reason the Germans didn't do multi-stage superchargers, even though they certainly had the technology to do so:: The improved performance was not justified for the cost increase. The engineers were simply trying to give the pilot the maximum possible performance with the most cost-effective tech available (existing engines and fuel supplies).

 

Later, they realized they had pushed too far on the pressure, and dialed back the maximum boost available to safer limits (1.3ata). All that was required, though, was for the mechanics to reset the engine to 1.42ata maximum...

Edited by Venturi
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7 hours ago, Ishtaru said:

 

And if detonation caused through low octane fuel is the reason for such short timers. Why does the 190 also has short timers with C3 fuel then?

 

The 190 uses C3 fuel all the time. One of the reasons it was used less on the East than the West (good luck using captured Russian fuel supplies... but maybe in a B4 using Bf109?). The BMW 801D requires 100oct + fuel. What the "C3 system" in the game does, is super-enrich the air/fuel mix so that detonation is retarded.

 

So detonation happens just 2 minutes later in high octane fuel but the Ash82FN, which is comparable to the BMW(?), dont have any detonation issues and can run at higher performance forever where BMW have to be time limited even at lower powersettings of 1.3ata. There is no time limit at 1.36ata for the Ash82FN and the cooling efficiency is superb so no drag at even the highest powersettings of 1.60ata even at summer temps.

 

There are many inconsistencies in the engine modeling, which is one of the reasons physics and engine basics need to be employed on a widescale basis in the sim, rather than the ad-hoc system that we have now. Part of that modeling would require an understanding of what fuel each plane is running on.

 

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It could take weeks to get fuel from refineries to airfields, especially late war.

 

german-oil-production-1944.jpg

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Guys, if we want something to change in the game, I believe asking for far-fetched long-term goals (i.e. more complex engine model) won't get us anywhere quickly.

 

However, if we focus on collecting the evidence to debunk the 1-minute myth for bf109-f-onwards aircraft, and enough people write to the devs, we may actually get their attention, get the timings fixed, and finally aftewards can start requesting general (for all aircraft) engine model improvements.

 

 

19 hours ago, Grim said:


I read that the detonation problem was also solved when they changed the ignation point for 2°. But it seemed that the detonation wear was the smaller problem.

@WEP timing

I heard a interview where a LW Pilot referred to the G-6 WEP. They where allowed to use it for 5 minutes because you head to revise the engine if you would use it any longer.
In actual combat he never used it longer then 1 minute. ..but he didnt explained why.

 

 

Could you find that interview? While, again, interviews are not the best source of "proof" (manuals and testing is), it would still be handy to have.

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Since were posting anecdotes, Ill post one that has a little more relevance and is alot more revealing. 


When I was overseas in 44 and 45, flying the J winter thru summer,
the policy was to drop tanks and push up MP to 45 inches when German fighters
were spotted in a position where an engagement was likely.  When you actually
went for them, throttle up to WEP, 60 inches or so, rpm all the way up too, up
past 3000 rpm.  And there it would stay until the engagement was over and you
remembered to throttle back.  You could easily be at WEP for 20 minutes or
more."

 

Note the important bit here that it was the POLICY of his unit to do this. Were the time-limits of engines actually based on preventing kaboom, then this would have been impossible. 

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