FW190A-8 Erhöhte Notleistung - Boost - how does it work

[sevenless]

48 minutes ago, 1stCL/Fucida said:

@CUJO_1970 @PainGod85 Yes, totally agree.

 

Current implementation of limits is simply wrong. When there was installed BMW 801 with Erhöhte Notleistung, there wasn't any limit for lower pressures. The only limit was 10 minutes for 1,58/1,65. I must repeat again what I've written above: The engine equipped with Erhöhte Notleistung was upgraded by stronger pistons developed for BMW 801 F, different vents from magnesium and different spark plugs. That all resulted in cancelation of former limits and setting of the new one (10 minutes @ 1,58/1,65).

 

The original document corroborates this:

 

Quote:

 

 

Source:

http://www.wwiiaircraftperformance.org/fw190/Fw_190_A-8_15-3-44.pdf

Edited July 25, 2018 by sevenless

[Arsenal53]

37 minutes ago, Sgt_Joch said:

 

No, the 3 minute limit is clearly stated in the manual. If it was cancelled, they would have taken it out.

 

I don't think so, the boost increase to 1.58 / 1.65 was made possible simply besause that the limits of the engine have been pushed further, it's different from the injection of A5 fuel. It could, in this manner sustain a higher pressure in the cylinders thanks to the engine modification. If the pressure can be higher then it must be logical that the engine must sustain a lower pressure for a longer time. As for the manual, they simply added a paragraph descibing this new feature. If the limitation at 1.42 had remained they would have written it on the new inscription near the button but they don't

[Sgt_Joch]

well again, did you guys even bother reading the "official" flight manual I posted? it explains very clearly how the system works.

 

The "emergency system" is a separate system. The pilot has to push the throttle to 100% AND pull a lever to get the system to work. That is what triggers the changes in the ECU and the increased fuel flow.

 

If you don't engage the system, i.e. you do not pull the lever, the ECU works normally, i.e. as in the A-3 and A-5 which is why the 3min/1.42 limit is still applicable.

 

Now is 3 minute too conservative, yah probably as as been discussed endlessly umpteenth time without coming any closer to resolution. Right now you have an effective 7 minute limit which is good enough until the Devs actually implement a better engine model.

[JtD]

35 minutes ago, 1stCL/Fucida said:

 I know about limits or let's say regimes by german engines (Dauerleistung, Steig und Kampfleistung, Start und Notleistung, and some kinds of Sondernotleistung). The BMW 801 D-2 with Erhöhte Notleistung was one of few, where wasn't usage of former pressures limited, but similar situation appeared also a little bit later by Fw 190 D-9.

 

In case of the BMW801 I have pilot manual, that contains both the 1.42/2700 Takeoff/Emergency 3minute rating as well erhöhte Notleistung, albeit with C3 injection, explicitly without time limit.

In case of the Jumo213 I have an engine card, that gives both the 3250rpm take off rating as well as the special emergency.

I also have technical data at least as late as December 1944 that state the take off rating of the BMW801D as ~1800hp, i.e. the 1.42ata performance.

I see no way that the take off rating of 1.42/2700 was overwritten/replaced by 1.58ata, given the fact that activation of this system on the ground was prohibited.

 

So, I tend to maintain my point of view that the increased power settings did not replace other ratings in the manuals, unless you provide a more suitable manual for a late war Fw190A/BMW801D.

 

Good thing is, I guess, we agree that from a technical point of view this is nonsense.

[PainGod85]

9 minutes ago, Sgt_Joch said:

well again, did you guys even bother reading the "official" flight manual I posted? it explains very clearly how the system works.

 

The "emergency system" is a separate system. The pilot has to push the throttle to 100% AND pull a lever to get the system to work. That is what triggers the changes in the ECU and the increased fuel flow.

 

If you don't engage the system, i.e. you do not pull the lever, the ECU works normally, i.e. as in the A-3 and A-5 which is why the 3min/1.42 limit is still applicable.

 

Now is 3 minute too conservative, yah probably as as been discussed endlessly umpteenth time without coming any closer to resolution. Right now you have an effective 7 minute limit which is good enough until the Devs actually implement a better engine model.

 

And what does the lever do exactly? It tricks the Kommandogerät into thinking MAP is too low. Which means it simply forces more air into the intake manifold so there's more oxygen to burn.

 

Consecutively, from a mechanical perspective, there is no reason why the engine would sustain a lower MAP for less than one third of the time it could at maximum load.

 

The 3 minute limitation at 1.42 ATA is nothing but an outdated relic at this point.

 

Also, do you not understand the 3 minute limit at 1.42 ATA was tested and found to still apply even with the boost system engaged?

1 minute ago, JtD said:

I see no way that the take off rating of 1.42/2700 was overwritten/replaced by 1.58ata, given the fact that activation of this system on the ground was prohibited.

 

That was almost certainly the case because the supercharger couldn't supply the higher MAP without ram.

[DD_Arthur]

1 hour ago, sevenless said:

 

Just out of curiosity...who translated this into english? And when was it translated into english? Focke-Wulf surely didn´t publish english handbooks about top secret stuff in 1944?

 

Sorry for the slight derail again but this is a very good question.  Where do these faux flight manuals in english come from?  I can imagine that the original manuals which fell into allied hands were transcribed into english pretty quickly but I can't imagine they would take the trouble to create a fascimile of the original FW document.

 

It would be a straight technical translation.  

 

I can't see any identifying marks on the PDF version at all.

 

@Sgt_Joch;  not any sort of knocking of your arguments btw, just a straight question

[Sgt_Joch]

8 minutes ago, PainGod85 said:

 

Also, do you not understand the 3 minute limit at 1.42 ATA was tested and found to still apply even with the boost system engaged?

 

 

And again do you not understand that the emergency system will only work if the throttle is at 100% (i.e 1.58/1.65) AND the system is engaged. It is not possible to engage the system at 1.42.

Edited July 25, 2018 by Sgt_Joch

[1stCL/Fucida]

Correct @sevenless, but be careful, the document, which you've sent, is OK, but that page, which you've quoted, is related to C3-Einspritzung. Erhöhte Notleistung is described on pages 3 and 4 (Blätter 4 und 5). and unfortunately there are not many details

 

16 minutes ago, JtD said:

Good thing is, I guess, we agree that from a technical point of view this is nonsense.

 

Yes

7 minutes ago, Sgt_Joch said:

And again do you not understand that the emergency system will only work if the throttle is at 100% (i.e 1.58/1.65) AND the system is engaged. It is not possible to engage the system at 1.42.

 

Of course it was technically possible to engage it in any conditions. But it was prohibited. The system should be started when the engine worked with full throttle, so 2700 rpm and 1,42 ATA. I think, that the main reason for this instruction was in not optimal Kommandogerät's functionality when the governor was fooled. A little bit later revision called BMW 801 TS offered complex solution with recalibrated Kommandogerät and of course with all mentioned improvements (vents, pistons, sprak plugs) as standard 

Edited July 25, 2018 by 1stCL/Fucida

[CUJO_1970]

1 hour ago, JtD said:

 

The BMW801D was cleared for erhöhte Notleistung and 1.58/1.65 ata, just like the TU. The relevant differences between the two models were armour thicknesses and oil cooler - the engine as such is the same in both cases. The game explicitly states BMW801D, for what it's worth.

 

Thanks JtD! I always appreciate your input and have learned much from you over the years.

 

I suppose you could say both TS and TU were variants of 801D, leading up to proposed (but not realized) serial production of 801F. (?)

 

My reason in distinguishing the two powerplants (D2/TU) is that TU incorporated more and higher strength parts from 801F development program than did earlier series D2. So, 801D2 (F-600) engines in the earlier series A8 were distinguished from 801TU "power eggs" in later production. Finally with 801TS power egg as you know, lead to a complete different designation from FW190 A8 to A9 as it benefited even more from 801F development.

 

BMW 801 D2 = early A8 with 1.42ata

BMW 801 TU = later A8, more parts applied to 801D from 801F development allowing 1.58 and 1.65ata.

BMW 801 TS = A9, most powerful BMW 801 to see series production.

 

That is my understanding of A8/A9 power eggs. Any insight of course is welcomed and appreciated.

 

[Arsenal53]

23 minutes ago, Sgt_Joch said:

 

And again do you not understand that the emergency system will only work if the throttle is at 100% (i.e 1.58/1.65) AND the system is engaged. It is not possible to engage the system at 1.42.

  yes it is perfectly understandable: without this system, impossible to draw more power from the engine. But the question is to know what is the reason of such limitation? it is the engine modifications (i mean the BMW801 F parts as pistons) that allow it to resist longer, isn't it?

Edited July 25, 2018 by Arsenal53

[3./JG15_Kampf]

What causes the engine to fail at 2700RPM 1.42ATA with restriction of 3 minutes? What causes the engine to not fail at 2700RPM 1.58 / 1.65ATA after 3 minutes?
We do not have C3 injection (FW190A5 / U17) which cools the engine at fw190A8

[PainGod85]

17 minutes ago, Sgt_Joch said:

 

And again do you not understand that the emergency system will only work if the throttle is at 100% (i.e 1.58/1.65) AND the system is engaged. It is not possible to engage the system at 1.42.

 

Yeah, because it was a hack job.

 

1. Do you agree the boost system on the A-8 increased manifold air pressure and nothing else due to the way it was constructed?

 

2. If yes, do you know of any other WW2 engine that used the same principle of (over)boosting an engine where time limits are growing more stringent with decreasing boost?

 

3. If no, do you believe BMW's engine factory operated on a different set of physics fundamentally incompatible with the one the rest of the planet was working with?

[CUJO_1970]

This is a very interesting technical discussion (IMO), no need for anyone to get excited ?

 

We are just trying to understand how these engines worked exactly.

[1stCL/Fucida]

3 minutes ago, 3./JG15_Kampf said:

What causes the engine to fail at 2700RPM 1.42ATA with restriction of 3 minutes? What causes the engine to not fail at 2700RPM 1.58 / 1.65ATA after 3 minutes?
We do not have C3 injection (FW190A5 / U17) which cools the engine at fw190A8

 

Upgraded engine. Especially stronger pistons developed for BMW 801 F, different exhaust's vents (from magnesium) and different spark plugs.

[CUJO_1970]

6 minutes ago, 3./JG15_Kampf said:

What causes the engine to not fail at 2700RPM 1.58 / 1.65ATA after 3 minutes?
We do not have C3 injection (FW190A5 / U17) which cools the engine at fw190A8

 

More powerful engine parts from 801F development as well as redesigned oil and cooling systems (greater capacities)

 

As far as cooling - even though the system is different from earlier C3 injection for A5, there were still some cooling properties from the additional air/fuel flow.

[3./JG15_Kampf]

5 minutes ago, 1stCL/Fucida said:

Upgraded engine. Especially stronger pistons developed for BMW 801 F, different exhaust's vents (from magnesium) and different spark plugs.

So the 3 minute limit for 1.42 ATA can be extinguished

[CUJO_1970]

The thing that we don't understand is this:

 

How can the A8 in flight be possibly capable of running higher boost pressures 1.65ata along with the higher cylinder head temps associated with it, while simultaneously having a 3 minute limit applied at a lower boost pressure (1.42ata) and lower cylinder head temperatures?

 

This doesn't make any sense.

 

 

[PainGod85]

1 minute ago, CUJO_1970 said:

The thing that we don't understand is this:

 

How can the A8 in flight be possibly capable of running higher boost pressures 1.65ata along with the higher cylinder head temps associated with it, while simultaneously having a 3 minute limit applied at a lower boost pressure (1.42ata) and lower cylinder head temperatures?

 

This doesn't make any sense.

 

 

 

The Germans found a way to run their engines on a different, inferior set of physics man, it's obvious!

[CUJO_1970]

4 minutes ago, 3./JG15_Kampf said:

So the 3 minute limit for 1.42 ATA can be extinguished

 

The only reason for it to remain may be restriction of higher boost pressures being forbidden on the ground due to lack of ram - as noted above by @PainGod85

[Sgt_Joch]

29 minutes ago, 3./JG15_Kampf said:

What causes the engine to fail at 2700RPM 1.42ATA with restriction of 3 minutes? What causes the engine to not fail at 2700RPM 1.58 / 1.65ATA after 3 minutes?
We do not have C3 injection (FW190A5 / U17) which cools the engine at fw190A8

 

I dont want to spend too much time on this since the system is complex and and not all the technical documentation agrees. What limits all engines, including the BMW is a combination of physical limits, heat, octane level, etc.

 

The ECU handles higher boost by steadily increasing mixture level to a very rich level, which is somewhat wasteful on gas and has other side effects, but does cool the engine somewhat and also retards the onsent of pre-ignition/detonation. There is a NACA document that explains this clearly. In the A-3/A-5, this effectively limited the "safe" boost level at 1.42 ATA since this was the effective limit of the fuel pump. Just increasing the boost would have just led to an increasingly lean mixture and unacceptable risks of pre-igniton/detonation.

 

In the A-8, larger capacity fuel pumps were installed so that the ECU could go to even higher mixture levels, i.e. a very very rich setting to partially compensate for the 1.58/1.65 setting. This is done by tricking the ECU which causes the much higher fuel flow, roughly 22% higher at 1.65 than 1.42 even though boost only increases by 16%.

 

Again I presume it would have been more elegant to redesign the ECU from scratch so that fuel flow would have been handled seamlessly all the way to 1.65 and the 1.42/3min. limit would be obsolete, but instead they went with this two-step system (no doubt for cost reasons), so you have the standard ECU with the same fuel flow/mixture setting at 1.42 ata and when the "emergency system" is activated increased fuel flow to handle 1.58/1.65.

 

That is how you get to this somewhat incongruous result that 1.42 is limited to 3 minutes when the regular ECU is working and 1.65 is limited to 10 minutes when the emergency system is activated.

Edited July 25, 2018 by Sgt_Joch

[PainGod85]

12 minutes ago, Sgt_Joch said:

 

I dont want to spend too much time on this since the system is complex and and not all the technical documentation agrees. What limits all engines, including the BMW is a combination of physical limits, heat, octane level, etc.

 

So why does the A-8's engine at lower cylinder head and oil temperatures at a lower boost setting die sooner than when it's running hotter on a higher boost?

 

Quote

The ECU handles higher boost by steadily increasing mixture level to a very rich level, which is somewhat wasteful on gas and has other side effects, but does cool the engine somewhat and also retards the onsent of pre-ignition/detonation. There is a NACA document that explains this clearly. In the A-3/A-5, this effectively limited the "safe" boost level at 1.42 ATA since this was the effective limit of the fuel pump. Just increasing the boost would have just led to an increasingly lean mixture and unacceptable risks of pre-igniton/detonation.

 

In the A-8, they replaced the fuel pump with one that has higher capacity. As such the C3 injection was rendered superfluous.

 

Following your train of logic, since the Kommandogerät is being tricked into allowing higher boost pressures (and since by your own admission mixture composition should be a function of boost pressure, shouldn't this mean mixture at 1.42 ATA and boost not engaged should be the same as with 1.58 // 1.65 ATA and boost engaged?

And if this is true, why is a richer engine setting sinking proportionally more heat into unburnt fuel while also producing less heat more destructive on the engine than at emergency overboost?

 

Quote

In the A-8, larger capacity fuel pumps were installed so that the ECU could go to even higher mixture levels, i.e. a very very rich setting to partially compensate for the 1.58/1.65 setting. This is done by tricking the ECU which causes the much higher fuel flow, roughly 22% higher at 1.65 than 1.42 even though boost only increases by 16%.

 

No. C3 injection in the earlier models, introduced because the fuel pump couldn't handle the volume of fuel flow necessary, was introduced to circumvent the issue. The larger fuel pump on the A-8 replaced that system.

 

Quote

Again I presume it would have been more elegant to redesign the ECU from scratch so that fuel flow would have been handled seamlessly all the way to 1.65 and the 1.42/3min. limit would be obsolete, but instead they went with this two-step system (no doubt for cost reasons), so you have the standard ECU with the same fuel flow/mixture setting at 1.42 ata and when the "emergency system" is activated increased fuel flow to handle 1.58/1.65.

 

You mean, like they eventually intended to do? And they didn't do it for cost reasons, they did it to get the higher boost to the fighter squadrons as soon as possible.

 

E: Wait one, I'll deconstruct your answer from the inside.

Edited July 25, 2018 by PainGod85

[JV69badatflyski]

Sgt_joch, it's so easy to understand, really.
Bmw received help through the Vril departement from inner-earth habitants.
What actually happens is some physical trick. The engine do not goes to1.65, that's just a placebo effect on the gauge for the pilot.
When the pilot push the button, the engine metal changes it's properties, due to the Vril trick, it activates it's transformation to Stalinium, as everyone knows, Stalinium is a living metal forged by inner-earth habitants in antarctica and known  for it's response when assaulted.
The Combustion process beeing considered as an agression by Stalinium, this last defend itself by reaction to heat through a heat expulsion process at molecular level, that's why the engine in 1.42 can be exploded after 3min because molecular level is like the iron cast one but once 1.65 button is pushed it's able to cool itself until a certain stress level.
But germans forgot to add the xanax injection , this way Stalinium could have been less stressed and could allow an auto coolling for much longer than 10min.
it's a shame their pharma industry was so bombed they didin't have enough stock to use.
 

Otherwise: can you prove at 100% that the following manual that has been like since 2005/2006 on the web is th full document with all adendums present?

[Sgt_Joch]

3 minutes ago, PainGod85 said:

 

So why does the A-8's engine at lower cylinder head and oil temperatures at a lower boost setting die sooner than when it's running hotter on a higher boost?

 

if it is running at a leaner mixture at 1.42, pre-ignition/detonation could occur sooner than at 1.65 with a richer mixture.

Edited July 25, 2018 by Sgt_Joch

[JV69badatflyski]

3 minutes ago, Sgt_Joch said:

 

if it is running at a leaner mixture at 1.42, pre-ignition/detonation could occur sooner than at 1.65 with a richer mixture.

1.32 is already rich and there is no pre ignition, 1.42 is full rich , 1.65 is like "ooooh mwoooore candy pliz"
 

[sevenless]

26 minutes ago, CUJO_1970 said:

The thing that we don't understand is this:

 

How can the A8 in flight be possibly capable of running higher boost pressures 1.65ata along with the higher cylinder head temps associated with it, while simultaneously having a 3 minute limit applied at a lower boost pressure (1.42ata) and lower cylinder head temperatures?

 

This doesn't make any sense.

 

 

 

I think the answer is written down here:

 

 

Baubeschreibung 284 (http://www.wwiiaircraftperformance.org/fw190/td284.pdf)

 

Basically we have the following situation:

 

A8 until 07/44 with BMW 801 D2 (F600) boost pressure (1.42ata) 3min

A8 since 07/44 with BMW 801 TU boost pressure (Boden 1,58ata and Höhe 1,65ata) 10min

 

What is BMW 801 TU? It is a 801 D2 supplemented with parts of the 801 TS/TH.

 

So planes with the TU engine had the 1,58ata/1,65ata boost, while planes with D2 engine were limited to 1,42ata boost.

Edited July 25, 2018 by sevenless

[-TBC-AeroAce]

I'm not saying the model is correct nor do i have an explination but after studying a lot of physics and engineering I have learned that things often do not work in the linear fashion you would expect. 

 

It is defo wrong just assume that it is wrong because there may be many factors why the engine has a shorter time limit at a lower ATA, I guess we are all here to work that out.

[Sgt_Joch]

well again if you guys have no interest in understanding how the ECU works, I will leave you to play your childish internet games.

 

for everyone else who is really interested, you should check out this document (especially page 11 and figures 17 and 18).

 

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093290.pdf

 

I will be back when the children have gone to bed. 

Edited July 25, 2018 by Sgt_Joch

[JtD]

There is no technical reason for 1.42ata/2700 rpm being more stressful that 1.58ata/2700rpm. In case of the first supercharger gear, the engine runs a leaner mixture at a higher boost and power. And even in second supercharger gear, I'm certain that both thermodynamically and mechanically 1.65 is harsher than 1.42.

 

The BMW801D (F-600) was cleared for erhöhte Notleistung. It's explicitly mentioned in the documents ("TU suitable for erhöhte Notleistung just like F600"). One cannot distinguish the D from the TU by that.

[PainGod85]

5 minutes ago, Sgt_Joch said:

well again if you gauys have no interest in understanding how the ECU works, I will leave you to play your childish internet games.

 

for everyone else who is really interested, you should check out this document (especially page 11 and figures 17 and 18).

 

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930093290.pdf

 

I will be back when the children have gone to bed. 

 

Switch to rich mixture at 2150 RPM.

 

No mention of overboost equipment on the engine.

 

Your own document source undermines your opinion.

[JV69badatflyski]

Damneeeed, paingod was faster.
Not to mention: what has it to do with 1.65 clearance by RLM?

[CUJO_1970]

17 minutes ago, JtD said:

The BMW801D (F-600) was cleared for erhöhte Notleistung. It's explicitly mentioned in the documents ("TU suitable for erhöhte Notleistung just like F600"). One cannot distinguish the D from the TU by that.

 

OK, understood.

 

Would you say that primary factors then to distinguish BMW801D (F-600) from TU and TS powerplants is then what components/systems were added from BMW801F development?

 

Also, is there any source we know of that documents what specifically what was included for each variant to require a new designation?

[-TBC-AeroAce]

28 minutes ago, JtD said:

I'm certain that both thermodynamically and mechanically 1.65 is harsher than 1.42.

 

 

 

In no way am I suggesting the following is what is happening but mechanically resonance could cause it to break at a lower ATA/rpm compared to a higher settings.

 

Also thermodynamically a weaker or disturbed boundary layer in the engine flow causing higher heat transfer could kill an engine at lower settings.

 

They are just the first two phenomenon I could think of and trust me there is a crap load more that could cause failure at lower settings. Simple are not these things are.

 

So no I don't agree with that statement at all.  Food for thought ?

Edited July 25, 2018 by AeroAce

[sevenless]

3 hours ago, JtD said:

 

The BMW801D was cleared for erhöhte Notleistung and 1.58/1.65 ata, just like the TU. The relevant differences between the two models were armour thicknesses and oil cooler - the engine as such is the same in both cases. The game explicitly states BMW801D, for what it's worth.

 

Where can we find the evidence that the BMW801D was capable of 1,58ata/1,65ata? Can you provide source and maybe a scan of the manual/paper? I find this astonishing because the Germans didn´t explicitely term the TU variant of the D2 with TS/TH parts for nothing. 

[PainGod85]

21 minutes ago, AeroAce said:

 

In no way am I suggesting the following is what is happening but mechanically resonance could cause it to break at a lower ATA/rpm compared to a higher settings.

 

Also thermodynamically a weaker or disturbed boundary layer in the engine flow causing higher heat transfer could kill an engine at lower settings.

 

They are just the first two phenomenon I could think of and trust me there is a crap load more that could cause failure at lower settings. Simple are not these things are.

 

So no I don't agree with that statement at all.  Food for thought ?

 

So mechanical resonance at 2700 RPM and 1.42 ATA is harsher on the engine than at 2700 RPM and 1.65 ATA? Ok.

[-TBC-AeroAce]

17 hours ago, PainGod85 said:

 

So mechanical resonance at 2700 RPM and 1.42 ATA is harsher on the engine than at 2700 RPM and 1.65 ATA? Ok.

 

[Edited] that is why i put ata/rpm settings.

 

Your missing my point which is that engines can break at lowers setting compared to highers ones due to certain things!!

[PainGod85]

1 minute ago, AeroAce said:

 

smart arse that is why i put ata/rpm settings

 

And what does this even have to do with engine durability at constant RPM?

 

Also, why should interrupted airflow in the induction system lead to lowered engine life? Why should it lead to increased engine life while at higher boost?

 

Have you ever heard of Occam's Razor?

 

If it walks like a duck and quacks like a duck, it's probably a duck.

[1stCL/Fucida]

 

2 minutes ago, PainGod85 said:

Have you ever heard of Occam's Razor?

 

If it walks like a duck and quacks like a duck, it's probably a duck.

 

Exactly. I don't understand, why some our friends here are trying to defend so huge mistake like current engine limit implementation. And they are still walking around and thinking about wilder and wilder theory, how could it be technically possible.

 

Ehmmm ?

[303_Bies]

 

10 hours ago, 1stCL/Fucida said:

I don't understand, why some our friends here are trying to defend so huge mistake like current engine limit implementation.

 

Maybe because it has beed coded by professional engineers with access to more source documents than we have. And probably with grater knowledge.

I'm not saying 1.58/65 ATA longer limit is correct or not, i don't know, i'm just saying it may be right.

We can discuss, but if the devs have the documents which support their model they will not change it.

If it is a mistake, a huge mistake like you said, they would know about that immediately, because it is more logical to have longer limit with smaller pressure, so probably they did it consciously with some reason behind the decision.

I can hardly imagine they didn't think about that.

And FW190A-8's BMW801 still run 1 minute longer with 1.42 ATA than A3 and A5 according to the test from previous page.

cheers

Edited July 26, 2018 by bies

[1stCL/Fucida]

@bies All the people, which are deeply interested in Fw 190 & BMW 801 knows the reason. It's implementation of well know (and not only here many times mentioned) manual, where is the original BMW 801 D-2 and also "upgrade kit" so-called Erhöhte Notleistung für Jäger.

 

Anyway I guess, that the developers will fix that silly implementation. Currently it simply doesn't make a sense.

[JtD]

18 hours ago, CUJO_1970 said:

Would you say that primary factors then to distinguish BMW801D (F-600) from TU and TS powerplants is then what components/systems were added from BMW801F development?

 

Also, is there any source we know of that documents what specifically what was included for each variant to require a new designation?

 

The Focke Wulf book by Peter Rodeike on page 270 contains a Focke Wulf memo dated August 3rd, 1944 which says (in short):

BMW801TH power plant (BMW801F engine) - problems, serial production unknown.

BMW801TU power plant - bastard power plant, interchangeable with F600: engine of BMW801D, cooler of BMW801F, oil tank of D/TH, 10mm nose armour (instead of 6), tank 6mm armour (instead of 4), 60kg heavier than F600, erhöhte Notleistung useable as with F600, no change / marking of A-8/F-8 equipped with TU

BMW801TS power plant - new power plant planned for autumn 1944, substitute for TH, same power as TH, engine improved 801S, rest of the power plant like TU, interchangeable with F600 and TU, no erhöhte Notleistung (insufficient reduction gear), 120kg heavier than F600, equipped aircraft to be designated A-9/F-9

 

I think that's a good summary. Basically speaking of a BMW801TU power plant still means the BMW801D engine, as the 801D engine at this time was working both in the F600 and TU power plants. I didn't realize that as clearly as now, where I've been typing the text I've read a couple of times already...

 

18 hours ago, AeroAce said:

In no way am I suggesting the following is what is happening but mechanically resonance could cause it to break at a lower ATA/rpm compared to a higher settings.

 

Also thermodynamically a weaker or disturbed boundary layer in the engine flow causing higher heat transfer could kill an engine at lower settings.

 

They are just the first two phenomenon I could think of and trust me there is a crap load more that could cause failure at lower settings. Simple are not these things are.

 

Yeah possible. That's pretty academic thinking, tough, given that the mechanical frequencies don't change and that the engine runs hotter at higher boosts. So I'll deliver an academic counter argument - erhöhte Notleistung above full throttle altitude can deliver exactly 1.42ata@2700rpm and would still be cleared for 10 minutes. Once you close the valve, absolutely nothing changes in the engine, but now it's only cleared for 3 minutes.

 

18 hours ago, sevenless said:

Where can we find the evidence that the BMW801D was capable of 1,58ata/1,65ata? Can you provide source and maybe a scan of the manual/paper? I find this astonishing because the Germans didn´t explicitely term the TU variant of the D2 with TS/TH parts for nothing.

 

Well, looking at the proper designations I transcribed above the TU power plant is in fact a D engine. Sorry for being messy with the designations myself. The other power plant found on the Fw190A-8 is the F600 power plant, but, as can also be seen in the transcription above, erhöhte Notleistung was cleared for it as well. After all, it's the same engine, just with a different cooler and extra armour.

 

---

 

We should all remember that engine development isn't really mirrored by updated designations. When we remade the Hurricane FM for Il-2:1946 I did a lot of research for the MerlinXX engine. Now we my all know that the early variant came with up to 12lb boost, optional Tilly orifice modification and a later 14/16lb boost version. And that's it. Truth is, however, that the list of changes done to the engine is a 450 page long list, containing dozens of changes for literally every subcomponent. At some time, the sum of all these changes allowed the clearance of a higher boost. And all these engines are equally labelled "XX". You can bet this is also true for the BMW801, so I wouldn't really put too much emphasis on designations. An early D has pretty much nothing to do with a late D (even when not labelled D-2).