BF109 Engine Damage in boost/emergency mode

[Fern]

I'm sure it's been brought up before about the engine damage in the 109s. I know each mode has a time limit.

 

Yesterday I went full throttle in the E-7 in boost mode. Around the 1 minute mark the engine blew up. The thing is, there was no indicator on my gauges saying the engine was overheating. This was during winter time also.

 

Is it just a time limit that blows my engine or some other factor?

[Finkeren]

Yep, once you go past the time limit, the engine suffers catastrophic damage after a random amount of time - shorter time the shorter the time limit. Nothing to do with overheating, it is simply mechanical failure.

 

It is a very strict system that hits planes with very short time limits on their highest power setting extra hard - in particular the Bf 109s and the P-40.

 

This has been debated to no end. I'm personally not a fan of the current system, but I do recognize the need to limit the use of emergency power somehow.

Edited October 12, 2017 by Finkeren

[Fern]

Thanks Finkeren. An indicator on the 109s and P-40 would be nice. I would just think, as long as you dont exceed your engine limits the engine should be ok. Sorry to bring this topic up again.

[Finkeren]

There is an indicator. It is part of the technochat.

[sniperton]

Just for curiosity, how was it in RL where no technochat was available to pilots? Did they have to rely on their instrumental or biological clock alone, or were they alarmed by a different engine sound or the like that the time were going off? Sorry if it has been discussed elsewhere.

[Nocke]

I would guess if you overstress a combustion engine to the point of mechanical failure - then it would anyways be too late to prevent it when you hear it?

[Willy__]

 

 

The thing is, there was no indicator on my gauges saying the engine was overheating. This was during winter time also.

 

The engine damage wasnt because of overheating. 

[Finkeren]

Just for curiosity, how was it in RL where no technochat was available to pilots? Did they have to rely on their instrumental or biological clock alone, or were they alarmed by a different engine sound or the like that the time were going off? Sorry if it has been discussed elsewhere.

In real life the engine didn't break like it does in the sim just because you used emergency power for a couple minutes too long. Instead it severely shortened the lifetime of the engine before complete overhaul.

 

To simulate the restrictions real life pilots were under in the use of emergency power, a random breakage is modeled when limits are exceeded.

 

Personally I think they are playing these restrictions far too strict. Yes, there should be a risk involved in exceeding limits, but it shouldn't be a complete breakdown within a couple minutes.

[JtD]

I would guess if you overstress a combustion engine to the point of mechanical failure - then it would anyways be too late to prevent it when you hear it?

No, typical reactions of the engine would be pre-detonation and knocking, which would be heard and felt by the pilot. Additionally, minor systems would typically be the first to fail, say a single piston losing compression by burning piston rings or damaging the piston surface, exhaust valves getting burned and not being able to close any more, exhaust stacks getting burned off changing gas dynamics and sound - all things you'd definitely feel and could (should) react to, without having instant engine failure.

[GridiroN]

The BF109 currently does not display water temp, i believe it only displays oil temp.

 

In any event,it's just a wear and tear simulation meant to simulate damage from stress as there is nothing to keep the player from not playin realistically and running the engines past factory recommended.

[LukeFF]

 

 

The BF109 currently does not display water temp, i believe it only displays oil temp.

 

All of them show water temperature; it's only the E right now that shows oil temperature.

[JG5_Schuck]

No, typical reactions of the engine would be pre-detonation and knocking, which would be heard and felt by the pilot. Additionally, minor systems would typically be the first to fail, say a single piston losing compression by burning piston rings or damaging the piston surface, exhaust valves getting burned and not being able to close any more, exhaust stacks getting burned off changing gas dynamics and sound - all things you'd definitely feel and could (should) react to, without having instant engine failure.

 

Most engines in this game seem to fail due to mechanical stress (unless you run it with the rads closed and the temp over 100 degrees for a period of time).

So yes by the time you hear or feel anything wrong, the damage is done!

Big ends, little ends, cam and crank main bearings tend to go with a bang and quite dramatic instant engine failure at high RPM.

 

And i do believe the Air-cooled engines do show oil temps, either inlet or outlet temps to the cooler.

 

Fw190 shows intake temp and needs to be run at 40-60 degrees, not 80-100.

[sniperton]

Thanks guys for your response!

 

Most engines in this game seem to fail due to mechanical stress.

So yes by the time you hear or feel anything wrong, the damage is done!

 

I understand how it works in the game, but, if I understand correctly, engine failure in RL is not discrete (a good engine doesn't suddenly turn into a bad engine), but rather the result of a longer process where the pilot can hear and feel that things are going south already before fatal and irreversible damage to the engine actually occures. Please correct me if I'm wrong, but I picture this for myself as something like a pre-stall warning or buffeting of the airframe, where damage can be prevented if immediate action is taken (e.g. throttle back).

I wonder whether it would be realistic to have an 'engine overstressed' type of engine sound as a warning sign before the engine gives up due to a longer misuse.

[JG5_Schuck]

It depends on the type of failure,

Ive been a technician for a number of years and engines can 'let go' with a bang or knock for days before finally dying.

Sometimes you can have warning signs, overheat, loss of oil pressure, vibration or harsh noise..... other times nothing, and BANG a rod can come through the block.

In the game there seems to be two distinct types of failure, overheat and mechanical failure, with one keep an eye on temps, and the other the revs and boost (limited time) you can find the specs for each aircraft in game.

Its actually quite hard to break an engine if you stick to these.

[sniperton]

I try to keep to the limits (my ride is the P-40 most of the time), but without the technochat I can barely see/feel in what engine regime I'm actually in (continuous/combat/emergency), and even if I can see it thank to the technochat, I cannot do anything to prevent an instant engine failure other than not using combat or emergency power at all. I'm only halfways towards the arcane knowledge of when that bloody engine will finally give up, and I wonder whether RL pilots were so much delivered to their sixth sense as I am. I'm not criticizing the game or how engine damage is modelled, I'm just curious about how WWII pilots did (or did not) overcome this issue.

Edited October 12, 2017 by sniperton

[GridiroN]

All of them show water temperature; it's only the E right now that shows oil temperature.

 

But if I'm not mistaken, The F, and G models have a temperature indicator on the right side that in real life could be switched between oil and water, but the sim only displays one of these, isn't that correct?

[LukeFF]

But if I'm not mistaken, The F, and G models have a temperature indicator on the right side that in real life could be switched between oil and water, but the sim only displays one of these, isn't that correct?

 

Yes, that's right. 

[Inkophile]

I try to keep to the limits (my ride is the P-40 most of the time), but without the technochat I can barely see/feel in what engine regime I'm actually in (continuous/combat/emergency), and even if I can see it thank to the technochat, I cannot do anything to prevent an instant engine failure other than not using combat or emergency power at all. I'm only halfways towards the arcane knowledge of when that bloody engine will finally give up, and I wonder whether RL pilots were so much delivered to their sixth sense as I am. I'm not criticizing the game or how engine damage is modelled, I'm just curious about how WWII pilots did (or did not) overcome this issue.

 

IRL you can hear the nuances of the engine better than we can in-game, but even then it'd require regular glancing down at the instruments. You should always check your manifold pressure, and more often so if you are in a situation where you'll cause it (and thus the need to adjust throttle) to change more rapidly, i.e. in all situations where you gain or lose speed/altitude with any rapidity.

 

You hardly need to be very precise about it. Running the engine at 2800 rpm and 43 inHg of power ("emergency" power as its 1 inHg more than full military) will make it survive faaaaaar longer than to run it at 3000 rpm and 56 inHg of power. As long as you stay in the ballpark of what power setting you intend to run at you'll do alright.

[sniperton]

I see, many thanks!

[Venturi]

56" limits are pretty hilarious.

 

The P-40 is pretty much the real indicator of the status of the engine modelling in this product.

[BlackBadger]

Can someone tell me if the limits are accumulative? i.e. if I fly 30s on emergency and then 5 minutes later I'll do 40 seconds do I trigger the random engine break algorithm?

 

If not, what is the cooldown period?

[YSoMadTovarisch]

Meanwhile the Yak 1B can go forever with rads closed in winter, reaching 610 kph TAS at 2500m, while the engine with WEP more or less immediately go busted for exceeding WEP time.

[Willy__]

 

 

Meanwhile the Yak 1B can go forever with rads closed in winter, reaching 610 kph TAS at 2500m, while the engine with WEP more or less immediately go busted for exceeding WEP time.

 

 

Not trying to defend that crap Yak, but these are two different things, while WEP will bust your engine because of mechanical failure, closing the rads will only make the temperature go up, if you are really really fast, it will take a long time for the heat to build up and start to damage the engine, but will do. The Yak at 100% isnt in WEP power.

[=RvE=Windmills]

Meanwhile the Yak 1B can go forever with rads closed in winter, reaching 610 kph TAS at 2500m, while the engine with WEP more or less immediately go busted for exceeding WEP time.

 

I just tried this and killed my engine in a few minutes?

[Barnacles]

Can someone tell me if the limits are accumulative? i.e. if I fly 30s on emergency and then 5 minutes later I'll do 40 seconds do I trigger the random engine break algorithm?

 

If not, what is the cooldown period?

 

I did some tests a while ago and it went a little something like this, aided by the technochat which will sometimes tell you 'emergency mode exceeded' then after a while 'emergency mode recovered.

 

I found that the p40's combat mode (5min) got recovered in 20mins, and it's emergency mode (2min) got recovered in 8 min. The 109 recovered in about 8 min as well. The LA5 recovered boosted mode (5min) in around 20mins. 

 

I'm not quite sure of the exact logic behind the timings, but I am sure that if you 'rest' your engine you do recover these time limits. It is also possible to do say 12 seconds of boost then 48 seconds of recovery and go like that for ages, or until you get bored, without risking engine damage.

 

I'll caveat this with I did the tests over 6 months ago, so things may have been tinkered with.

I just tried this and killed my engine in a few minutes?

 

Probably because the 'fact' you replied to can be filed along with a lot of the other 'rUssian planez are OP, OMG' nonsense.

[YSoMadTovarisch]

 

 

Not trying to defend that crap Yak, but these are two different things, while WEP will bust your engine because of mechanical failure, closing the rads will only make the temperature go up, if you are really really fast, it will take a long time for the heat to build up and start to damage the engine, but will do. The Yak at 100% isnt in WEP power.

 

I don't think if you fully close the rads, airflow gained  from speed will even help you.

[ZachariasX]

I don't think if you fully close the rads, airflow gained  from speed will even help you.

Fully closed is not least drag.

[Panthera]

Shouldn't the 109 be able to handle 1.42 ata for at least 5 min at a time though? IIRC the later models could run at even higher boost settings (1.8 to 1.98 ata) for 10 min at a time.

[Barnacles]

Shouldn't the 109 be able to handle 1.42 ata for at least 5 min at a time though? IIRC the later models could run at even higher boost settings (1.8 to 1.98 ata) for 10 min at a time.

 

The high ATAs for late 109s were permitted only with MW50 additive, as far as I know. What exactly was permitted and for how long also depended on whether C3 fuel or D4 fuel was being used. The Max boost for E7, F2, F4 and G4 is 1min in this game.

[Venturi]

The maximum possible boosts are always given by the fuel quality (octane rating).

 

This is why the DB60x series had to have quite a bit larger swept displacement to give an equivalent power to the 27L displacement Merlin / Allison.

 

Do a Google conversion of 1.42 ATA to inches of mercury, so see what the limitations to boost / results of having low-octane fuel are.

 

It's notable that the DB60x engines performed as well as they did on this lower octane fuel, and were no heavie than their smaller Allison or Merlin counterparts. However, if fuel is the limiting component to making more power... then you have to come up with an alternative method to reduce detonation, or forever be limited to a maximum power / L of swept displacement. And, that the Germans (and others) did... but it wasn't as effective, lightweight, or as elegant as simply having higher octane fuel to begin with.

[LColony_Kong]

The fact of the matter in all of this is that with perhaps 1 or 2 exceptions, there should be no limitations on boost time. 

 

Engine time limits had absolutely nothing to do with preventing engine failure in the manner we see in BOX, or other flight sims. They existed in order to preserve engine lifetime over multiple missions, and the time allowed involved considerations that stems not only from engineering concerns but also from whatever the tactical, doctrinal, and strategic situation was. The idea that these limits have to do with immediate failure mid mission is a pure game-isim. Many times during the war engines that had received NO modifications were allowed higher boost settings for the same time period. There are also ground run in tests of WEP settings that were over 8 hours long for some planes. Not to mention pilot anecdotes accounting for running max power for extensive periods of time over the manual limit. And anyone who has ever seen a time to climb test at WEP settings should have noticed that they somehow ran WEP for periods usually about 5 times longer than allowable to complete the test. What a miracle. 

 

This situation is somewhat analogous to OCing a GPU. Doing so properly will result in shorter lifespan of the card, but for all intensive purposes is not likely to cause immediate failure unless actual hard limits were breached. There is a big difference between exceeding a hard limit and wearing something out faster by running it constantly at a high setting. 

 

 

Debating what the time limit should be misses the entire point. 

All aircraft, unless there is specific evidence to the contrary, should NOT have time limits on their max engine settings. 

[Venturi]

Have to say, I disagree on that.

 

Detonation will kill an engine in short order. Flying at full boost the entire mission is ahistorical for the primary reason that it does in fact miss the point that using engines very hard can result in their failure, in short timeframes (during a mission). Although this may not happen every time...

 

I am reading a history right now of B-17 pilots, and it is repeatedly mentioned at different times, that some aircraft had to turn back from mission when trying to catch up to their formation - due to engines failure from excessive use of Manifold Pressure and RPM. There were no MP limiters on B-17s...

 

The point being, is that failure DOES need to be modeled for this to be a sim. The primary problem is not that the sim does this - but in the METHOD and WAY in which it is done.

[LColony_Kong]

Have to say, I disagree on that.

 

Detonation will kill an engine in short order. Flying at full boost the entire mission is ahistorical for the primary reason that it does in fact miss the point that using engines very hard can result in their failure, in short timeframes (during a mission). Although this may not happen every time...

 

I am reading a history right now of B-17 pilots, and it is repeatedly mentioned at different times, that some aircraft had to turn back from mission when trying to catch up to their formation - due to engines failure from excessive use of Manifold Pressure and RPM. There were no MP limiters on B-17s...

 

The point being, is that failure DOES need to be modeled for this to be a sim. The primary problem is not that the sim does this - but in the METHOD and WAY in which it is done.

Several things

 

-I did say there are exceptions to the rule. But they require specific evidence since the time limits have nothing to do with the sim notion in the first place. 

 

-If any airplane has no MP limiter, there is nothing to stop the pilot from going to a engine setting that exceeds the actual limits of the engine. This is analogous to using more volage than a GPU can actually handle our right...like 10 volts, instead of using a voltage that is functional but decreases the lifespan to something still on the order of years. 

 

-There are alot of other reasons that engine management at high altitude especially can cause failure that might seem power related but are not in the sense we are discussing here. Read about the woes of P-38 pilots for this. 

 

 

 

 

This really isn't a debatable issue. It is simply a mater of historical fact that the manual time limits for throttle settings are not for protection from destruction mid flight. They are there exclusively to prevent overly rapid wearing of the engine. That way you get 10 missions out of engine instead of 2-3. 

 

The idea that exceeding these limits (even for hours) will blow up the engine or kill it outright is for all intensive purposes a game fiction. It has been done so many times in sims that the sim community at large generally assumes it to be correct behavior. It is the coconut effect in action. 

Edited January 1, 2018 by Fumes

[Blutaar]

What was the "real cool off timer" for WEP in real life? :o

 

If an engine breaks while using WEP for longer then allowed it was already broken in the first place and could also break as soon as you go full throttle. How can anyone guarantee 1min, 3min or whatever amount of time when the engine is on the last flight before overhaul? I mean there is nothing mentioned in the manuals for such a case like "do not use WEP at all when your engine is old and must be replaced soon". 

The time limits are there for a reason so pilots dont use it longer then absolutely needed so that the engine will easily reach its lifespan before getting replaced. Most missions were flown without enemy contact and then such limits makes perfect sense but combat is another story. As long as your engine parameters are good you go full throttle as long as you need to survive. Back home you would tell your mechanic what you did and he decides what to do.

If engines would break so easy like portrayed ingame, engines would get restricted like for example in the 109 G2 i guess.

 

The comparison with overclocked CPUs/GPUs that Fumes did fits perfect.

[Venturi]

Actually, if you use the search feature (I note that you have only 35 posts to your name, Fume) - you will find it has been debated in threads many tens of pages long and with evidence far beyond what you're familiar with, I gather.

 

It is not a simple issue, but a few things stand out - and a major one is that detonation from high MP did kill engines, and that it was the primarily limiter of maximum possible boost.

 

Simple time limits were for guaranteed safe usage at that power level, only... and these were conservative limits (how conservative, depends on the particular engine and air force under discussion)... and do not necessarily reflect the mechanical underpinnings of the failure mode.

 

The TBO of the DB60x series (~150hrs) was far below that of the Merlin (~400hrs) and especially, the Allison (~700hrs) engines.

[SCG_OpticFlow]

What was the "real cool off timer" for WEP in real life? :o

 

If an engine breaks while using WEP for longer then allowed it was already broken in the first place and could also break as soon as you go full throttle. How can anyone guarantee 1min, 3min or whatever amount of time when the engine is on the last flight before overhaul? I mean there is nothing mentioned in the manuals for such a case like "do not use WEP at all when your engine is old and must be replaced soon". 

The time limits are there for a reason so pilots dont use it longer then absolutely needed so that the engine will easily reach its lifespan before getting replaced. Most missions were flown without enemy contact and then such limits makes perfect sense but combat is another story. As long as your engine parameters are good you go full throttle as long as you need to survive. Back home you would tell your mechanic what you did and he decides what to do.

If engines would break so easy like portrayed ingame, engines would get restricted like for example in the 109 G2 i guess.

 

The comparison with overclocked CPUs/GPUs that Fumes did fits perfect.

 

IRL the limits are prescribed from the manufacturer so that the engine would reach the specified hours between factory overhaul (200 hours for the DB-601E). More boost means shorter periods between overhaul. It is that simple.

[Blutaar]

IRL the limits are prescribed from the manufacturer so that the engine would reach the specified hours between factory overhaul (200 hours for the DB-601E). More boost means shorter periods between overhaul. It is that simple.

 

So tell me, how many times per mission was 1 min of full boost allowed for the DB-601E? How many minutes of full boost can you squeeze out of the 200hr before overhaul?

Edited January 1, 2018 by Ishtaru

[LColony_Kong]

Actually, if you use the search feature (I note that you have only 35 posts to your name, Fume) - you will find it has been debated in threads many tens of pages long and with evidence far beyond what you're familiar with, I gather.

 

It is not a simple issue, but a few things stand out - and a major one is that detonation from high MP did kill engines, and that it was the primarily limiter of maximum possible boost.

 

Simple time limits were for guaranteed safe usage at that power level, only... and these were conservative limits (how conservative, depends on the particular engine and air force under discussion)... and do not necessarily reflect the mechanical underpinnings of the failure mode.

 

The TBO of the DB60x series (~150hrs) was far below that of the Merlin (~400hrs) and especially, the Allison (~700hrs) engines.

I see we are commiting the classic "you arent a known quantity to me (35 posts) so I assume you are rube" rubbish. Typical forum bull. 

 

I am well familiar with the other threads on this forum that debated this issue. I have also discussed it at length with members of this community outside of this forum. I havent seen anything that would discredit what I just said to any significant degree. 

 

what you state about safe usage is totally false. The time limits were quasi-arbitrary numbers that existed ONLY to extend engine life to whatever was decided was needed. This is why engines repeatedly got uprated while keeping the same time limit. This is why there are manuals that specifically state this. This is why we have loads of pilot accounts of running engines well in excess without failure. This is why we have 8 hour WEP run ins. This is why a 109 carries enough MW50 for DOUBLE the manual allowed use even with breaks in between. 

 

Time limits are game fantasy. 

So tell me, how many times per mission was 1 min of full boost allowed for the DB-601E? How many minutes of full boost can you squeeze out of the 200hr before overhaul?

I cant speak to the E. But it was pretty common that engines that used WEP were replaced or worked over as soon as possible, regardless of how many hours on the. IIRC this was standard policy on Merlins in 51s. 

 

No pilot in his right mind stopped using max power because he exceeded a time limit in combat. If you get shot down, the engine life of 25 hours doesnt matter. 

[Venturi]

Well, if the devs want to develop a full engine simulator describing the various modes of engine failure (engine RPM / MP mismatch, causing detonation - engine mix too low for MP, causing detonation - engine mix too high for RPM/MP, causing plug fouling and cylinder misfires)... then by all means, I support it.

As I've written about extensively before... use search.

[SCG_OpticFlow]

So tell me, how many times per mission was 1 min of full boost allowed for the DB-601E? How many minutes of full boost can you squeeze out of the 200hr before overhaul?

 

If i understood correctly, the given values are per flight (i don't know how an average flight time is calculated).

 

I checked the engine service manual I had, it only says to keep the duration under Emergency power as short as possible. If you know German, I recommend to get it, its very detailed with nice color illustrations. Link (56 MB PDF):

 

http://www.deutscheluftwaffe.com/archiv/Dokumente/ABC/m/Motoren/Daimler%20Benz/Motorhandbuch%20DB%20601%20E-G.pdf

Edited January 1, 2018 by OpticFlow