DB 605A-1 1.42 ata (WEP) duration

[JtD]

47 minutes ago, LColony_Red_Comet said:

There is only one reason these limits exist on  ww2 aircraft: Time Before Overhaul.

 

No, that's not true either. There are plenty of example where excessive power settings and high power settings over a long time caused engine damage, not just an extra maintenance effort. Prop reduction gears reduced to metal dust, exhausts burned off, valves burned through, cylinders being knocked out, brokes pipes and torn hoses. These damages aren't necessarily related to coolant, cylinder head or oil temperature limits, and some result in catastrophic damage eventually.

None of the WW2 aero engines were 100% reliable in the first place and all of them suffered particularly under high stress, be it thermal or mechanical. Many aircraft and many pilots did not return to base because of engine failures. Just doing away with the limits is about as wrong as keeping them.

My personal vote is (and has been since the start) to replace it with some sort of stress based, randomized reliability model.

[LColony_Kong]

16 minutes ago, JtD said:

o, that's not true either. There are plenty of example where excessive power settings and high power settings over a long time caused engine damage, not just an extra maintenance effort. Prop reduction gears reduced to metal dust, exhausts burned off, valves burned through, cylinders being knocked out, brokes pipes and torn hoses. These damages aren't necessarily related to coolant, cylinder head or oil temperature limits, and some result in catastrophic damage eventually.

 

Yes it is.

 

Engines failed due to stress, but its not directly connected to the time limits in any of the manuals. And none of those limits pertain to avoiding said stress due to the risk of immediate failure (except in the very specific case of the 109s having a 1 minute limit on the then unauthorized 1.42ata). They are only there for the purpose of TBO. Engines failed at high power settings after use, but not BECAUSE someone violated the manual time limit. Some planes ran engine power settings that were beyond their rated powers. Who can say how many hours an engine had on it or what other conditions caused failure after high power use. Engines also failed when operating at non-emergency powers etc. etc.

 

 

 

 

19 minutes ago, JtD said:

None of the WW2 aero engines were 100% reliable in the first place and all of them suffered particularly under high stress, be it thermal or mechanical. Many aircraft and many pilots did not return to base because of engine failures. Just doing away with the limits is about as wrong as keeping them.

My personal vote is (and has been since the start) to replace it with some sort of stress based, randomized reliability model.

This is just special pleading. Please do apply this line of logic to every other mechanical thing in the game. Oh wait, no one does that. Where are the requests for engines to just randomly fail even at continuous power? Gun jamming? Brake failure? Air-frame warping? I mean we could go on about this all day. Putting RNG in for engines is just flat out ridiculous.

[JtD]

 

48 minutes ago, LColony_Red_Comet said:

They are only there for the purpose of TBO.

No, they are also there because running high power settings all day did not fulfill the requirement of the "accepted operational safety", which was required from all aircraft components back in the day (in most countries, at least, and for as long as they didn't appear to lose a war). Without it, there was no acceptance of any component into operational use. Exceed the given limits, and you will get failure rates that were considered inacceptable.

 

45 minutes ago, LColony_Red_Comet said:

This is just special pleading.

No, it's something we've had in earlier iterations of Il-2 Sturmovik, where it worked well.
 

[41Sqn_Skipper]

4 hours ago, LColony_Red_Comet said:

There is only one reason these limits exist on  ww2 aircraft: Time Before Overhaul. That is it. Nothing else.

 

 

 

Air Publication 2095 Pilots Notes General, 2nd Edition clearly disagrees:

 

 

"The limitations are designed to secure an adequate margin of safety against immediate breakdown and to give a reasonable life between overhauls."

 

[CountZero]

They should fix techchat message first because if they build system that punish player so harsh compared to how it worked in real ww2.

If i can see techchat message that tels me when game wonts me to stop i can somehow go with this arcade system. Its easy way to make it better but they still dont wont to fix it.

There is no way that in real ww2 pilot care more about some saving time for overhale of engines when he was in battle, he didnt have to know exact seconds he used it like we are forced to do in game, so thats why its important that broken messages that inform player when hes safe time ended work. They build them in game but tied them to wrong realisam option that have nothing to do with techchat messages.

For me i dont expect them to make new engine timer system as its to long for them to do so, but to fix few broken tech chat messages should not be to hard for them to do if they cared about it, no action regarding this just shows they dont care about it. Same like problem with nav lights, its small and easy bug to do compared to other stuff, but its still glaring problem in game.

Edited November 7, 2021 by CountZero

[the_emperor]

Well, I know the engine timer itself is a hot topic that needs to be discussed please stay on topic. this is not about the timer itself but if the current one of this specific engine in the game logic we have is correct.

Cheers ?

[Raven109]

17 hours ago, the_emperor said:

f@Raven109

thank you very much for your work and extensive testing. 

 

No worries. 

 

17 hours ago, the_emperor said:

Does the damage also happen when above FTH where boost is around 1.2-1.3 and rpm at 2800?  

 

Yes, the damage happens also with these settings. Can't infer a precise pattern, since I don't have the time to run extensive tests, however it seems that reducing ata to anything in the range of 0.7-1.3 while holding 2800rpm will almost double the base no-damage period - i.e. it will go from 1 min up to 1min:50s. After this new base period has elapsed, the damage will occur at a random interval and with random intensity, just like it did for 1.42ata/2800rpm. 

 

Holding ata constant (e.g. 1.3ata) and reducing rpm, e.g. from 2800rpm to 2700rpm, will raise the base period even more from ~1min50s to ~5min30s. Reducing rpm to a bit above 2650 will lead to the base period being over 22 min.

 

At least for the 109g6 early, the game seems to consider that you are in the Emergency mode once you go above 2650rpm, regardless if ata is at 0.7. Both ata and rpm are used as factors when scaling the timer, and rpm has the most weight. Timer scaling most probably occurs between the minimum timer value for the previous operation mode (e.g. 30 min for 1.3ata/2650rpm) and the minimum timer value for the current power mode (i.e. 1.42ata/2800rpm - 1 min).

 

Edited November 7, 2021 by Raven109

[Raven109]

12 hours ago, LColony_Red_Comet said:

No this is just a generalized procedure to get the pilot to not run the engine a high power without need. If there really was a thermal problem, a silly procedure like this would do you zero good. What speed are you flying at? What altitude? What engine power were you using before you initiated WEP? How hot is it outside? Etc. You cant just stamp on some rubbish 10 min limit and think that will keep you in parameters if indeed there was such a thermal problem. Not to mention that the idea that the engine heated up over 10min to a critical condition, but is somehow ready for another 10min after only 5 minutes is some fairly absurd sounding thermodynamics. Odd isnt it, that this hypothesized thermal problem has such exact parameters across numerous 109 variants using different engines?  And on top of all this, what condition of engine are we assuming for this procedure? If a new engine lasts 10 minutes, what about a worn out one? Do you think the pilot is really going to take a 5 minute break with a Mustang up its ass?

 

There is a simple explanation. This is not war thunder. They did not have thermal time limits.

 

There is only one reason these limits exist on  ww2 aircraft: Time Before Overhaul. That is it. Nothing else. And there is tons of explicit and implicit proof of this that has been posted by myself and others on this forum regarding many different aircraft over the years.

 

 

 

Well, if I were to tell someone to follow a rule during wartime, I would make sure that the rule would lean to cover the most extreme conditions. So, in the case of high power regimes I would tell them the period of time for a hot day, for a plane which is running close to stall speed, basically the worst case scenario.

 

If your entire response is directed at me, I would suggest you (re-)read my posts. Nowhere do I say that within 10 minutes of operating at maximum power the engine is taken to a critical condition. Rather, what I'm thinking about is that the 10 minutes of high power operation lead to a condition which can exponentially reduce the engine life/TBO and <<occasionally (think along the lines of e.g. 5%)>> it lead to engine failure, depending on the state of the engine. 

 

Also, when I'm talking about overheating, I'm referring to local hot spots in the context of engine knock (e.g. spark plugs, carbon deposits overheating and becoming a source for detonation). Knock is not a condition which will always ruin an engine outright, although it can depending on its severity.

 

The manual we were discussing about is for the G-14. For cases where B4 fuel was used, the manual states that you should reduce the throttle immediately  to 1.3 ata once you run out of MW50, otherwise the engine will be destroyed .

 

As you see, the engine can be run at a power setting which leads to instant damage. Of course, MW50 was used to significantly reduce (hopefully eliminate) this situation. The question is, did it do it even after running the engine at full boost for over 10 minutes? 

 

I am well aware of the discussion regarding TBO.

Edited November 7, 2021 by Raven109

[41Sqn_Skipper]

2 hours ago, Raven109 said:

 

As you see, the engine can be run at a power setting which leads to instant damage.

 

Maybe it just loweres TBO to 3 sec 

[the_emperor]

I found the time to do some testing.

I did use only the Kuban autumn map as it is often referenced as the standard map (atmospheric pressure wize):

WEP Test throttle to 2800rpm:

Below FTH the warning message for "emergency time exceeded " seems to pop up at "exactly" 1min, after that engine damage occurs randomly between 0:30 and 2:00.

Above FTH (tested at 7000m,9000m,10000m) it gets weired: that same pattern occurs "always" after 2 minutes instead of 1. Height, and therefor the drecreasing boost, does not seem to matter...

It seems that below FTH a combination of rpm and boost are  limiting factors and above FTH it are rpm only that limit WEP use.

[JtD]

Maybe both, rpm and boost, contribute 50% each towards the "overload" condition, and if one is within limits, it takes twice as long to fill the overboost condition stack solely with the other.

[the_emperor]

@JtD yeah, that seems to be the simplified case for the WEP modell of the 109G6 here...

But I have not tested the other case thus far (Below FTH/manually set to 2600rpm, or lower/boost to 1.42ata)

[Raven109]

2 hours ago, the_emperor said:

I found the time to do some testing.

I did use only the Kuban autumn map as it is often referenced as the standard map (atmospheric pressure wize):

WEP Test throttle to 2800rpm:

Below FTH the warning message for "emergency time exceeded " seems to pop up at "exactly" 1min, after that engine damage occurs randomly between 0:30 and 2:00.

Above FTH (tested at 7000m,9000m,10000m) it gets weired: that same pattern occurs "always" after 2 minutes instead of 1. Height, and therefor the drecreasing boost, does not seem to matter...

It seems that below FTH a combination of rpm and boost are  limiting factors and above FTH it are rpm only that limit WEP use.

 

the_emperor, thank you. This is in-line with what I've found and described in my last post about the timers.

 

There is one note though, the behavior is not getting weirder above FTH. What you are noticing is the influence of altitude on ATA and since ATA starts dropping at a certain altitude,  the timer value will start increasing as a consequence. If you run a test below FTH you'll notice the same results, once ATA drops below 1.3 (so it's outside the Emergency power setting interval), the timer will only be increased if rpm is reduced.

 

Below are some extrapolated graphs. I don't have enough data points since it's a pain waiting for up to 30min for a technochat message to appear, so the ramps might not be linear in-game, but I think they're a good approximation.

 

 

 

The blue area is where no damage occurs. Once time is outside the blue area, random damage can occur after a random period of time. Previous tests have shown that this period is between ~0 - ~3min, with a higher probability of the damage to occur in the lower half of the range.

 

As you can see the max timer for the 1.3ata/2650rpm setting is close to 30min which matches the time period for the Climb and Combat power setting as given by the manual.

Edited November 8, 2021 by Raven109

[the_emperor]

thank you @Raven109.

with "weird" I ment, that the decreasing boost itself does not seem to have the effect I thought it would have above FTH on the WEPtimer. it seems more influenced by the rpm setting. though did only measure time till WEP warning appears.

Will have more deeper look into it tonight but will limit that to the kuban autumn map only.

Thanks again?

 

Edited November 8, 2021 by the_emperor

[the_emperor]

I did some more testing this is what I came up with thus far. Tested on Kuban Autunm throttle/Boost set to automatic.

10.000m/2.800rpm/0.92ata → 2min till WEP exceeded warning

9.000m/2.800rpm/1.04ata → 2min till WEP exceeded warning

8.000m/2.800rpm/1.17ata → 2min till WEP exceeded warning

7.000m/2.800rpm/1.31ata → 2min till WEP exceeded warning

6.500m/2.800rpm/1.39ata → 1:20min till WEP exceeded warning

so everthing in line with your testing @Raven109 just not as visually appealing ?

 

this begs the question, why cant the engine withstand 2800rpm for more than 2 min before the WEP warning pops up when the boost setting is well below the limits, while the MW50 injected engines can do?

My guess (and it is just a guess) we are still missing the revised DB605A engine ingame for the the second half of 1943, and the devs chose for some kind of hybrid model, lifting the ban but sticking to the 1 minute limit of the DB601E engine? Probably missing data themself for the usage of WEP after the engine was revised.

Personally I think they should look into it with the upcomming Normandy module. since flying a 109-G4/6 with access to more WEP duration still puts you at an disandventage vs the Packard/Merlin 18lbs driven Mustang/Spitfires perfomance wise. Of course only if the WEP ban lift is justified by the time frame (I am absolutely OK with keeping the WEP-ban, where it is historically correct for G4/G6 models).

 

[Raven109]

In the G14, where MW50 is available, once you push the throttle past 93-95% of its movement range, MW50 will be injected into the compressor intake, and it will reduce the risk of detonation due to its properties. MW is injected regardless of what the current ATA value is as long as ATA is above a minimum value (1.2ata) which is used to pump the fluid. It's all based on the physical position of the throttle lever, so basically at higher alts you can be running at "non-damaging" ata values, but still at 2800rpm and active MW injection.

 

I'm assuming that the game engine is looking at high ATA and/or RPM values as factors that increase the chance of detonation (heat build-up both due to the compressor working harder to provide the higher boost and also due to mechanical stress and friction between engine components at high RPM). Once MW50 is being injected, the game engine will reduce the risk of detonation caused by high ATA/RPM. 

 

If you take the G-14 at lower alts where you can pull back the throttle such that it doesn't engage the MW system, but still hold high ATA/RPM (1.42ata/2800rpm) values, you'll find that the G-14 has the same timer limits as the G-6, because without the MW-50 it's actually a G-6 (with minor differences, not relevant to this discussion).

 

I think you're right in your assumption that the post-ban DB605A is still using the 1 min limit for the banned value. That's because the only documents which list 1 min next to the 1.42ata/2800rpm setting are those which also prohibit pilots from using it.

 

As said before, the game models the ban in the form of the G-2 (also powered by DB605A) where it limits ata to 1.3. The G-4/-6/-14 are all supposed to model the DB605A after the ban was lifted. However, we have this legacy 1 min value timer in-game which has already been discussed to death on these forums (actually in this thread as well).

 

Attached is a document for the DB605A which might be the source of the 1 minute limit. Right below the table, note 1) is saying that the setting is blocked. Later documents don't show a time limit next to the Take-off and emergency setting.

 

Not sure who in their right mind would use such a power setting, if 1 minute later you could be hanging below your parachute since you're engine gave up on you, or even worse a fire engulfs your engine, if we are going to believe that the limit was so strict as it is in the game world. Usually a limit is declared with a certain safety margin, which I assume is what the random timer which starts after the 1 min limit in game is supposed to simulate, however it still seems too drastic for comfort, meaning that the engine completely self-destructs too often after the random value has been exceeded - but then again there was a war going on.

 

A good compromise, at least for the DB605A would be to decrease the chance of catastrophic failure once the random timer has elapsed, and also give more feedback to the pilot that something went wrong.

 

To wrap up my "dive" into engine timers for the 109G-6 early, below is a table showing timer values at different ata and RPM values.

 

 

 

Edited November 10, 2021 by Raven109
Added linked ata and RPM to the chart

[41Sqn_Skipper]

35 minutes ago, Raven109 said:

Later documents don't show a time limit next to the Take-off and emergency setting.

 

To be more precise: The later manuals don't show any time limits at all. With other words: There are time limits, but they are not given in that manual or that part of the manual. 

 

35 minutes ago, Raven109 said:

Not sure who in their right mind would use such a power setting,

 

Don't forget that the power limit it's also very important for take-off with short runways. In this case a 1 minute is feasible. 

 

[the_emperor]

8 hours ago, Raven109 said:

I'm assuming that the game engine is looking at high ATA and/or RPM values as factors that increase the chance of detonation (heat build-up both due to the compressor working harder to provide the higher boost and also due to mechanical stress and friction between engine components at high RPM). Once MW50 is being injected, the game engine will reduce the risk of detonation caused by high ATA/RPM. 

 

If you take the G-14 at lower alts where you can pull back the throttle such that it doesn't engage the MW system, but still hold high ATA/RPM (1.42ata/2800rpm) values, you'll find that the G-14 has the same timer limits as the G-6, because without the MW-50 it's actually a G-6 (with minor differences, not relevant to this discussion).

Thank you. But why is the usage of higher rpms depending on MW50 even in lower boost settings?

is there a technical reason for that or this is because of the game mechanic you described?

Cheers ?

 

[Roland_HUNter]

16 hours ago, Raven109 said:

In the G14, where MW50 is available, once you push the throttle past 93-95% of its movement range, MW50 will be injected into the compressor intake, and it will reduce the risk of detonation due to its properties. MW is injected regardless of what the current ATA value is as long as ATA is above a minimum value (1.2ata) which is used to pump the fluid. It's all based on the physical position of the throttle lever, so basically at higher alts you can be running at "non-damaging" ata values, but still at 2800rpm and active MW injection.

 

I'm assuming that the game engine is looking at high ATA and/or RPM values as factors that increase the chance of detonation (heat build-up both due to the compressor working harder to provide the higher boost and also due to mechanical stress and friction between engine components at high RPM). Once MW50 is being injected, the game engine will reduce the risk of detonation caused by high ATA/RPM. 

 

If you take the G-14 at lower alts where you can pull back the throttle such that it doesn't engage the MW system, but still hold high ATA/RPM (1.42ata/2800rpm) values, you'll find that the G-14 has the same timer limits as the G-6, because without the MW-50 it's actually a G-6 (with minor differences, not relevant to this discussion).

 

I think you're right in your assumption that the post-ban DB605A is still using the 1 min limit for the banned value. That's because the only documents which list 1 min next to the 1.42ata/2800rpm setting are those which also prohibit pilots from using it.

 

As said before, the game models the ban in the form of the G-2 (also powered by DB605A) where it limits ata to 1.3. The G-4/-6/-14 are all supposed to model the DB605A after the ban was lifted. However, we have this legacy 1 min value timer in-game which has already been discussed to death on these forums (actually in this thread as well).

 

Attached is a document for the DB605A which might be the source of the 1 minute limit. Right below the table, note 1) is saying that the setting is blocked. Later documents don't show a time limit next to the Take-off and emergency setting.

 

Not sure who in their right mind would use such a power setting, if 1 minute later you could be hanging below your parachute since you're engine gave up on you, or even worse a fire engulfs your engine, if we are going to believe that the limit was so strict as it is in the game world. Usually a limit is declared with a certain safety margin, which I assume is what the random timer which starts after the 1 min limit in game is supposed to simulate, however it still seems too drastic for comfort, meaning that the engine completely self-destructs too often after the random value has been exceeded - but then again there was a war going on.

 

A good compromise, at least for the DB605A would be to decrease the chance of catastrophic failure once the random timer has elapsed, and also give more feedback to the pilot that something went wrong.

 

To wrap up my "dive" into engine timers for the 109G-6 early, below is a table showing timer values at different ata and RPM values.

 

 

Did you checked the historical documents in this topic on pages 1-6?

[Raven109]

  

20 hours ago, 41Sqn_Skipper said:

Don't forget that the power limit it's also very important for take-off with short runways. In this case a 1 minute is feasible. 

 

I agree, however the setting is named Take-off and Emergency, and I'm assuming most here are concerned with the emergency part. 

 

11 hours ago, the_emperor said:

Thank you. But why is the usage of higher rpms depending on MW50 even in lower boost settings?

is there a technical reason for that or this is because of the game mechanic you described?

Cheers ?

 

 

I'd say that it's just a game mechanic. High RPM can lead to engine wear and stress, but I doubt it was an immediate issue for the DB605 engine. An even worse condition for an engine would be low-medium RPM coupled with a high load (boost), though, but this is not modeled. IRL there was no benefit to using MW50 when running at lower boost and 2800rpm, as the G14 manual states.

 

3 hours ago, Roland_HUNter said:

Did you checked the historical documents in this topic on pages 1-6?

 

Yes.

Edited November 9, 2021 by Raven109

[Venturi]

On 11/6/2021 at 10:29 PM, JtD said:

My personal vote is (and has been since the start) to replace it with some sort of stress based, randomized reliability model.

I seem to recall someone detailing that.

 

One thing that is conspicuously missing are the consequences to lean mix, high boost. And high boost, low RPM.

[the_emperor]

I found some additional mentioning of the 1 Minute limit in a BF-110 G-2/R manual dating from July 1943

It says limit for 1 Minute but still banned

 

 

 

The August/September issue for the manual of the G-3/G-4 dont mention any duration for any setting (emergency/climb,combat/continious).

So far the 1 minute duration is actually all that is mentioned but only when the ban is still in effect, thus far no mentioning of duration limit after the ban lift.

Cheers ?

Edited November 10, 2021 by the_emperor

[the_emperor]

The D.(Luft)T.3605 Motoren-Karte from September 1942 still mentions the WEP ban but gives further informations:

1) it seems that it is specificaly blocked to not overrev the engine (so maybe more an rpm issue than an boost issue?): "2650rpm (2600rpm +2%) must not be exceeded under any cirumstance"

2) no time limit for the use of WEP (though it is still blocked and therefore not usable):

"If WEP is used, the engine is heavily stressed, so use of  WEP only in an emergency situation"
.

 

 

The D. (Luft) T. 2109 G-6/U4 (Stand 1943) issued Februar 1944

mentions the D.(Luft)T.6605 Motoren-Karte (so probably the 6th issue of that manual). does any one have access to that issue or maybe D.(Luft)T.4605 or D.(Luft)T.5605. I guess the would bring some enlightenment

Edited November 11, 2021 by the_emperor

[the_emperor]

I found a manual from Juli 1944. There are no limits to the engine except temperature/pressure for oil and coolant and of course fuel consumption and the advise to use WEP sparingly and only in emergency situations:

From ´44:

 

 

There is differences though, the Cooling system of the revised engine is higher pressurized namely with 1.00atü instead of 0.75atü and can run slightly higher temperature 102°C at all altitudes from 0km-15km while the earler engine can rund 102°C only up to 6.75km height

and the revised engine has a slightly diffrent setting of rpm/boost in the lower throttle settings:

from:´42

From: ´44

Edited November 11, 2021 by the_emperor

[41Sqn_Skipper]

3 hours ago, the_emperor said:

...

 

I'm a bit confused which page is from what year in your post. 

 

Also, what's the "**)" footnote in July 1944?

[the_emperor]

12 minutes ago, 41Sqn_Skipper said:

I'm a bit confused which page is from what year in your post. 

 

Also, what's the "**)" footnote in July 1944?

I did mark the 44 and 42 manual.

there is no **) footnote only the *) footnote regarding boost varriing during climb and the rev limit of 2870rpm

probably a typo in the manual or a copy and paste mistake from the older manual from 1942.

Edited November 11, 2021 by the_emperor

[Raven109]

Nvm, misread.

10 hours ago, the_emperor said:

1) it seems that it is specificaly blocked to not overrev the engine (so maybe more an rpm issue than an boost issue?): "2650rpm (2600rpm +2%) must not be exceeded under any cirumstance"

 

The 1.42 ata ban was because the bearings would overheat due to foaming of the oil. So, higher revs, more parts moving, more heat, and oil pumps were connected to the crankshaft, which meant they spun faster - possibly what caused the foaming.

It's interesting to note the behavior of engine damage when the banned 1.42 ata setting was used:

 

<<The take-off and emergency output with a boost pressure of 1.42 atm. and 2800 revs. may not at present be used. The climbing and combat output with 1.3 atm. and 2600 revs. may, in the case of the older engines (for works numbers see below), be used when operationally essential.

 

If, in spite of these regulations, a piston does burn through, this is indicated by a strong regular vibration of the engine.

It is still possible to reach the nearest friendly base if the stress is immidiately reduced to about 1600 revs. and the lowest possible boost pressure. The vibration of the engine as a result of piston damage remains unchanged when both magneto 1 and magneto 2 are switched on, so that it is possible to confuse it with the a damaged sparking plug. On the bench, bursts of blue vapour are emitted from the housing ventillatorwhen a piston is damaged.

In engines with reinforced pistons the danger of their burning through is not so great as in the older version of the piston, but the take-off and emergency output may still not be used.>>

 

Source: http://kurfurst.org/Engine/Boostclearances/DB605_142ban_June1942.html

Edited November 11, 2021 by Raven109

[the_emperor]

Thank you @Raven109

is there a document for the statement "The clearance for the 1,42 ata, 2800 R.P.M. 'Start und Notleistung' rating was ultimately given for service use in October 1943 after several improvements to the DB 605A powerplant."?

Thus far there are only the manual of the G-3/4 that dont mention the ban but not in detail like the "Motoren-Karte" of ´44.

Currently the WEP for the DB605 should be locked at least till autumn ´43 but still no evidence how it could be used until  ´44.

[the_emperor]

Currently it looks more like the DB605A should have WEP blocked till April 1944 According to the Engine Manual of 1944. Literally saying it replaces the Manual of 1942:

 

 

[41Sqn_Skipper]

On 11/11/2021 at 11:19 PM, the_emperor said:

Thank you @Raven109

is there a document for the statement "The clearance for the 1,42 ata, 2800 R.P.M. 'Start und Notleistung' rating was ultimately given for service use in October 1943 after several improvements to the DB 605A powerplant."?

Thus far there are only the manual of the G-3/4 that dont mention the ban but not in detail like the "Motoren-Karte" of ´44.

Currently the WEP for the DB605 should be locked at least till autumn ´43 but still no evidence how it could be used until  ´44.

 

Only a secondary source. 

 

 

Page 23 in 

 

 

[the_emperor]

Thanks @41Sqn_Skipper are there any footnotes one could follow up to that statement in the book?
 

[41Sqn_Skipper]

1 hour ago, the_emperor said:

Thanks @41Sqn_Skipper are there any footnotes one could follow up to that statement in the book?
 

 

No footnotes or source directory. 

[LColony_Kong]

On 11/7/2021 at 2:09 AM, JtD said:

No, they are also there because running high power settings all day did not fulfill the requirement of the "accepted operational safety", which was required from all aircraft components back in the day (in most countries, at least, and for as long as they didn't appear to lose a war). Without it, there was no acceptance of any component into operational use. Exceed the given limits, and you will get failure rates that were considered inacceptable.

This is counterfactual and also entirely illogical given the state of affairs these engines were operating under. We have multiple manuals that state clearly and unambiguously that the time limits have to do with keep the engines running a certain number of hours before the have to be overhauled or replaced. We have reports by Rolls Royce documenting typical failure times of over 25 hours or so at full power. We also have multiple tests with allisons, merlins, and r-2800s running nearly 8 hours at WEP for the very purpose of establishing that the WEP rating was safe to use. This is among many many documents I have posted on this matter, including the excerpt from "Aeronautics for Naval Aviators" which also states that the time limits are for TBO purposes.

 

How many sources do I need JTD? How many manuals and documents do I need that state over and over again what I have been saying this entire time?

 

On top of all this it is patently ridiculous that the timer limits of a few minutes on these engines would have given any useful margin of safety given what they were. If an engine is being pressed to the limit such that you expect failure at 5 minutes, even with a standard engineering margin of safety like say 50%, this is so close to the limit that it might as well be useless. Precisely because of the all the finicky behavior that ww2 piston engines exhibited, and that you guys on that side of this issue love to point out. % minutes or boom? Spare me. There would be no assurance, much less anything that could be considered "acceptable operational safety", if the timer were only 5 minutes because such a narrow margin would be not only extremely hard for a pilot to keep track of, but would be out the window as soon as the plane got any use. Every ounce of wear and tear, much less WEP, would reduce any assurance that this tiny time limit would hold...were it the case that that is what the time constraint was for.

 

The purpose to the time limits was simply to prevent wanton use of the engines that would wear them out too quickly and pose unnecessary risks.

 

And I have never stated that it was reasonable for pilots to just fly around at WEP all the time in real life. The point is that the engines were capable of it, and the time limits had nothing to do with preventing an immediate failure due to exceeding the timer.

 

What I have stated is that given how long we KNOW the engines could handle WEP, there is no reason in this game or IRL that pilots should be tactically ham stringed by time limits whose real life purpose has little relevance to this game.

[ZachariasX]

3 hours ago, LColony_Red_Comet said:

The point is that the engines were capable of it, and the time limits had nothing to do with preventing an immediate failure due to exceeding the timer.

You are talking of high performance engines. I give you an example of a timer, one that you can see about every two weeks. F1.

 

An F1 car can go full bore for about 5 km straight, give it take. You can expect the engine to explode before you reached the 10 km mark. By not exceeding a timer corresponding to a 2.5 km straight, you can operate the engine for several (single digit though, like the later DB) hours. This equates to a 30 sec useable „WEP setting“ based on a 1 min destructive timer. That is what you can do if you have fancy computers aboard and telemetry that monitor every milisecond of engine life.

 

Going full bore will not make the engine make fewer hours as TBO, but it will make it a „1 min until new build“- engine.

 

Also you should be careful comparing bench runs with running the engine in aircraft in the old days. Bench runs provide an ideal environment for the engine (it has to be for the sake of a controlled experiment), in aircraft it is less so. If the engine blows after 5 min on a certain rating on the bench, you will NOT clear that engine for 1 min in aircraft.

 

EDIT: This just to say that a) it is very easy to let engines run on a timer as we have it and b) it is surprisingly easy to let engines that qualifly for longer times at given rating on the bench run on such a timer, as it is always the weakest component (that might not even be present on a bench run) that sets the engine as a whole in the red.

Edited December 11, 2021 by ZachariasX

[41Sqn_Skipper]

3 hours ago, LColony_Red_Comet said:

There would be no assurance, much less anything that could be considered "acceptable operational safety", if the timer were only 5 minutes because such a narrow margin would be not only extremely hard for a pilot to keep track of, but would be out the window as soon as the plane got any use. Every ounce of wear and tear, much less WEP, would reduce any assurance that this tiny time limit would hold...were it the case that that is what the time constraint was for.

 

Now just assume that the aircraft you have in the sim is not factory new, but has already seen much use and abuse. Then the small safety margin is very plausible.

[the_emperor]

6 hours ago, LColony_Red_Comet said:

The purpose to the time limits was simply to prevent wanton use of the engines that would wear them out too quickly and pose unnecessary risks.

At least the manual for the revised DB 605A (April ´44) supports the assumtion. There is no time Limit on the WEP use and the manuals says, it should be used when starting on small airfields and/or heavy loaded plane. And: "The engine is heavily stressed during emergency power, so this power can only be used in an emergency"

that engine also features an improved cooling system. This is also the engine which had to run and handle the increased power of the MW-50 with ~1700hp at 1.7ata/2800rpm (2x 10min).

The engine manual with the blocked WEP seems to be still in effect till ´44 and then was substituted for the new one. Maybe revised engines did reach frontline units earlier, but according the manuals, the blocked WEP was still in place till spring ´44 and was released in April 44. So for late G-4/G-6 at the eastern front which did not have the MW-50 installed, there should probably be no limit on the use of WEP (if we are following the game logic, that we always get a factory new/up to the specs aircraft)

[Bremspropeller]

10 minutes ago, the_emperor said:

There is no time Limit on the WEP use and the manuals says, it should be used when starting on small airfields and/or heavy loaded plane. And: "The engine is heavily stressed during emergency power, so this power can only be used in an emergency"

 "Start und Notleistung" isn't WEP. It's "Takeoff and Emergency Power". The manual advises to use T&EP for takeoffs on small airfields and/ or heavy aircraft.

Takeoffs on normal airfields are to be made with Steig- und Kampfleistung (Climb and Combat Power).

 

 

Edited December 11, 2021 by Bremspropeller

[the_emperor]

WEP = war emergency power = Notleistung (max rpm/boost)

in the context of what is for discussion here I would say its the same and easier to type and understand for the non-german speaking community?

Edited December 11, 2021 by the_emperor

[Bremspropeller]

6 minutes ago, the_emperor said:

WEP = war emergency power = Notleistung

 

No. WEP = War Emergency Power, which is a rating above Start- und Notleistung, which is the normal take-off rating (as the name says).

There is no german equivalent to WEP, except Sondernotleistung and MW50 or Erhöhte Notleistung.

 

 

[the_emperor]

all right. cut the W and call it Emergency Power ?

(max. rpm/max. boost = WEP or Notleistung to not confuse you)

but is that relevant for the engine rating, that is up for discussion here (2800rpm/1.42ata)?

Edited December 11, 2021 by the_emperor