About 1.98 Ata

[Roland_HUNter]

Greetings.
 

First of all, I have no idea if this topic is shared in the right place. I only want to post this topic as a way of getting to know you, not as a complaint.
 

I have read in the past that many people doubt that the 1.98 ata was used in combat during the war.
 

Well I would like to show that there is evidence that it was used.

1.98 was banned in 1945 january.
http://kurfurst.org/Engine/Boostclearances/DB_Niederschrift6730_DB605DBDC_20-1-45.pdf

 

But in 1945 March it was enabled for usage.
http://kurfurst.org/Engine/Boostclearances/605D_clearance198.html

I don't want to upload the German/Allied pictures you find in the link to the March 1945 authorization.



I have pulled out several other books on the subject to see if I can find anything.
Messerschmitt Bf 109 F, G, and K Series: An Illustrated Study  page 174:

 

Another interesting fact I've never heard of myself:

MESSERSCHMITT Bf 1 09 G-1 through K-4 by Jean-Claude MERMET
Page 11:

Pge 46:

Page 54:

And also he is mentions the 1.98 ata at page 20:

 

Other books like:
The Messerschmitt Bf 109 (Part 2) F to K Variants by Lynn Ritger page 14.:

 

This report shows they used 1.98 in 1944.12.20.

But yes, as I mentioned before, they banned the usage from 1945 jan until 1945 march.

They even tested the 1.98 for K-6 in 1944.12.11.
Messerschmitt Bf 109 GK (Flugzeug Profile 44) page 42:

 

Monogram Close-Up #16 Messerschmitt Bf 109 K by Thomas H. Hitchcock 1979 page 33 (pdf edition)
He mentions the same fighter formations using the 1.98 ata that you read in kurfurst's link above.

If this information and facts are not enough. Then I guess nothing is.

Thank you for reading.
If anyone knows more information on this, I would be happy for that person to share it with all of you.

 

PS:I found a forum thread on this site dealing with this topic, also looking for historical documents and presenting them as arguments.

 

[CUJO_1970]

Gib G10 Erla with MW50+C3 fuel please:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

G6 Late could have C3+MW50 as option also. This G6 Late landed behind British lines July 1944 - it was equipped with C3 fuel and MW-50 tank (as noted in the British report) It is an interesting 109 as it is a non-/AS G6 with the standard supercharger...

 

EDIT: Crash-landed Messerschmitt Bf 109G-6 (W.Nr 413601) 'Black 7', flown by Unteroffizier Jakob Vogel who made an emergency landing behind British lines on the 24th of July 1944.

 

 

 

 

Edited August 31, 2022 by CUJO_1970

[357th_KW]

The reason many believe it was never used operationally is because there are some very compelling arguments in that direction, and because the "evidence" of its use is pretty weak.  Mike Williams makes a strong case against it on his page, and I'll try to add some pieces to that.

 

The initial 109K-4 manual from November of 1944 lists emergency power as 1.75 ata. 

 

The single page of the report you have posted from December 20th is a summary of a meeting between Messerschmitt and Daimler-Benz, and simply states that in testing MW30 and MW50 results were within the tolerances of their test, and so the two could be used interchangeably.  It then goes on to describe that DB605D's setup for 1.8ata will be marked with a white B on the crankcase, and those setup for 1.98ata with a white C on the crankcase.  The very next point states that they don't have all the performance curves yet, but should be getting those from Daimler-Benz around January 3rd.  Which brings us to the next point.

 

Here are the testing results for the DB605D, reported on January 4th 1945.  They state that the engine tested at 1.98 ata failed.  "Despite several hours of careful flying of the engine at continuous power before the series of measurements with combat power, engine damage was found during the first test runs after the changeover to p = 1.98 ata, which made an engine change necessary".  It's clear at this point that these higher boost settings are still being trialed at the factory, and are most certainly not in use on operational aircraft.

 

An internal memo from Daimler-Benz from January 17th 1945, describing a meeting on January 10th.  The memo states that all four DB605DC engines supplied to Rechlin for testing failed.  As a result, 1.98 ata is not cleared for use.

 

DB document from January 19th 1945 stating that engines delivered from Kassel will be 605DB (1.8ata) models. 

 

Meeting notes from Rechlin, January 16th 1945 and from a Berlin conference on January 20th 1945.  These detail that 1.98ata is banned, and engines will be delivered with 1.8ata, pending further testing.  It's also mentioned here that II/JG11 will conduct testing - this is an interesting note.  II/JG11 (along with the rest of the Geschwader) was decimated over Y-29 on January 1st, and the whole unit will be relocated a few days later on the 23rd to the Berlin area.  Looking at Marek Murawski's unit history of JG11, the unit doesn't appear to have flown again on the western front after January 1st.  II/JG11 seems to have seen limited action against the Soviets around Berlin starting in February (the 190 equipped I and III gruppen seem to have been doing the bulk of the fighting), and there is no mention of any testing.  Murawski wraps up II/JG11's tale: "The lack of fuel by early April led to the dissolution of II./JG11."  Also of importance in these memos are mentions of fuel quality problems - we'll revisit this with some other sources.

 

Messerschmitt test report from January 16th through February 15th.  This states that 1.98ata was blocked and testing was done at 1.8ata.

 

Repair Instructions for DB605 from March 14th 1945.  "All changes are due to the requirement to be able to safely use B4 fuel of inferior quality for the performance-enhanced engines. Since fuel C3 is available in undiminished quality, engines 605 ASC and 605 DC, if they are built in this version, are supplied unchanged as before; however, since both new build and repairs are usually delivered in 605 ASB and 605 DB versions, nearly all 605 engines are covered by these changes."  Again this only lists 1.8ata as the max allowable boost pressure.  Again we see notes of problems with B4 fuel quality.  In the repair instructions, it shows the different MW50 spray nozzle settings for the 605ASC and 605DC engines - essentially they are using a lower MW50 flow rate, which makes sense as these engines would be running higher octane fuel, of better overall quality then the B4.

 

Here I'm going to insert a quote from Callum Douglas' "The Secret Horsepower Race" pg 414-416

         "Kollmann (Chief Designer at Daimler-Benz) noted on January 25, 1945, that fuel quality issues were arising again.  With the situation inside Germany now reaching desperate levels for the engineers, Kollmann sat down and wrote his report on the current state of engine detonation problems:  "The main cause for the occurrence of the white flame (detonation) was found to be the B4 fuel.  The flame characteristics showed when flown at 100 to 110% power levels, it was running in the knocking-zone.  This was confirmed by the smouldered appearance of the pistons.  When the new batches of B4 fuel arrived, suddenly the white flame appeared - this test was repeated in  a follow-up experiment but using this time C3 fuel, and alternatively the old stock of B4 fuel."  In all cases using the different fuel batch the white flames disappeared.  This is in contrast to the assurance given by OKL (Senior Air Staff Engineer Cuno) and Director Schilo, according to whom the latest fuel delivered should provide around 1.5 bar higher BMEP value in the fuel-knock test then the B4 standard - this assurance was also the basis for the original planning for possible engine power output at the time.  "This fuel which was already poor in quality, was furthermore degraded by the exceptionally high oil consumption in the engines, since as is well known, oil in the fuel reduces the knock-limit of the engine significantly.  The oil consumption measured on eight of these ten engines suggest that the consumption was on average 22kg/hour. (original emphasis)  This high oil consumption is on the one hand due to the fact that the engines were only loaded to 500ps on the initial warming up running period using propane and in the subsequent bedding-in run carried out very briefly - therefore they were not properly run in.  Conclusions: The setback suffered from the end of December 1944 due to white-flame can essentially be traced back to the reduced quality of the B4 fuel, up to this time there had already been 400-500 engines delivered without any significant faults.  The profile of the piston wear has to be improved, the oil consumption lowered, the valve seats have to be exchanged for permanently installed versions i.e. not threaded.  Until the anticipated improvement in fuel performance by increasing lead content to 0.16%, the ignition will be retarded.  If and when the ignition will again be set to the original value remains to be seen."

 

This is a very illustrative bit of evidence - not only was 1.98ata failing in testing, but fuel and build quality issues were causing problems with production engines running 1.8ata.  The ASC and DC engines running C3 fuel at 1.8ata were likely much more reliable then the much more common ASM and DB engines, as they at least had decent fuel to run on, although they likely suffered from the same knock limit reduction due to excessive oil consumption that the other DB engines were facing.

 

This brings us to the so-called "clearance of 1.98ata" you've linked to above.  We don't have the original document, and in fact Kurfurst's site just has its contents typed up in HTML.  The actual source appears to be the book Waffen Arsenal Messerschmitt Bf109 im Einsatz.  I was able to find a pdf copy of the book, and it doesn't contain the original document either.  What is clear in the book, is that this document isn't some engineering instruction, but rather the second of two lists from OKL describing what their goal is for equipping German units going forward.  The first list from February describes requipping units with He162s, 190D-12/13s, Ta-152s, Bf109K6s etc.  The authors of the book then say "Apparently reality set in, resulting in a revised target" - which is the second list that just aims at standardizing on the 109K-4 and mentions the uprated power for I and III/JG27 and III and IV JG53.  It's worth noting things on this second list that didn't happen, or are omitted.  For instance IV/JG27 isn't mentioned at all.  That's strange, given that they were an active Bf109 gruppe on March 20th when this document is dated.  Interestingly that unit was essentially wiped out the following day by a bombing attack on their airfield - the unit was disbanded and the pilots distributed amongst the other JG27 gruppen.  Looking at I/JG27, they are shown as having K-4s and uprgading to 1.98ata - but Marek Murawski's Vol IV of his unit history of JG27 has a picture of a I/JG27 G-14 in Wunstorf airfield in April 1945.  Likewise, if we look at II and III JG53, they are both described as being fully equipped with K-4's with III/JG53 uprgading to 1.98ata, and yet statements of members of those units describe receiving old G-6s as replacement aircraft in April of 1945.  It's clear that this document is just a set of general equipment plans, and it appears that many of them never came to pass.  It's also worth noting that Bf109 production ceased at the beginning of April 1945. 

 

In summary, we have a great deal of original documentation stating that 1.98 was restricted, and that engines were breaking in ideal factory conditions at that power level.  We also have evidence that production engines were struggling to even handle 1.8ata with poor quality B4 fuel in the field.  There is no documentation of the engines ever being cleared to run 1.98, or ever doing so in a production unit.  It's clear that the Luftwaffe wanted to do this, testing was done to try it and they wanted to do anything they could to improve the performance of late model 109s, but the evidence of operational use just isn't there.

[Roland_HUNter]

Good points, but I think this evidences is also worth looking at. :

 

[LukeFF]

2 hours ago, CUJO_1970 said:

G6 Late could have C3+MW50 as option also. This G6 Late landed behind British lines July 1944 - it was equipped with C3 fuel and MW-50 tank (as noted in the British report) It is an interesting 109 as it is a non-/AS G6 with the standard supercharger...

 

EDIT: Crash-landed Messerschmitt Bf 109G-6 (W.Nr 413601) 'Black 7', flown by Unteroffizier Jakob Vogel who made an emergency landing behind British lines on the 24th of July 1944.

 

 

 

The historical evidence indicates this was a G-14, not a late G-6: http://109lair.hobbyvista.com/articles/airframes/413601/413601_report.htm

[-=PHX=-SuperEtendard]

2 hours ago, CUJO_1970 said:

G6 Late could have C3+MW50 as option also. This G6 Late landed behind British lines July 1944 - it was equipped with C3 fuel and MW-50 tank (as noted in the British report) It is an interesting 109 as it is a non-/AS G6 with the standard supercharger...

 

EDIT: Crash-landed Messerschmitt Bf 109G-6 (W.Nr 413601) 'Black 7', flown by Unteroffizier Jakob Vogel who made an emergency landing behind British lines on the 24th of July 1944.

 

From what I understand as MW 50 started to be introduced, it was first used with C3 fuel as a safety measure: in case the injection system failed the C3 fuel would better tolerate the increased manifold pressure than B4 fuel, at least avoiding a catastrophic engine failure giving the pilot some time to decrease the throttle. It was still 1.7 ata for the same power output. Later on it was switched back to B4.

A few skins for the G-6 Late and G-14 in game from the June- July 1944 time period have C3 decals in them.




 

Edited August 31, 2022 by -=PHX=-SuperEtendard

[CUJO_1970]

3 hours ago, LukeFF said:

 

The historical evidence indicates this was a G-14, not a late G-6: http://109lair.hobbyvista.com/articles/airframes/413601/413601_report.htm

 

Well, it's complicated - but the only way to tell definitively is by the Werknummer block. 413601 is from Erla Leipzig G-6 production run.

413 400 - 413 900 Bf 109 G-6 Erla Maschinenwerk GmbH, Leipzig

 

G-14 Leipzig production did not begin until 461 100 - 461 999 production block, so there is no way this machine was produced as 109G-14.

 

With this being said, it's complicated  - a G-14 and G-6 Late at this stage were basically interchangeable.

 

We do know that the the LW used and British captured G-6 with both C3+MW/50. In some cases they used former GM-1 equipped aircraft.

 

 

Anyway, what I find interesting about these aircraft is those options paired with the normal 605 supercharger when they were mostly seen with the bigger supercharger of the 603.

 

 

3 hours ago, -=PHX=-SuperEtendard said:

From what I understand as MW 50 started to be introduced, it was first used with C3 fuel as a safety measure: in case the injection system failed the C3 fuel would better tolerate the increased manifold pressure than B4 fuel, at least avoiding a catastrophic engine failure giving the pilot some time to decrease the throttle. It was still 1.7 ata for the same power output. Later on it was switched back to B4.

 

When you say it was switched back to B4, do you mean for G6/G14?

There was of course this certain pilot that continued to get away with it:

 

C3 + MW50 was used of course in G10 and K4 in addition to the B4 fuel.

[-=PHX=-SuperEtendard]

17 hours ago, CUJO_1970 said:

We do know that the the LW used and British captured G-6 with both C3+MW/50. In some cases they used former GM-1 equipped aircraft.

 

 

Anyway, what I find interesting about these aircraft is those options paired with the normal 605 supercharger when they were mostly seen with the bigger supercharger of the 603.

 

When you say it was switched back to B4, do you mean for G6/G14?

There was of course this certain pilot that continued to get away with it:

There is not much to "get away with" really, probably his unit still had C3 stocks allocated, you use the fuel that you have, would still be 1.7 ata for 1800 PS at sea level for a G-6 / G-14, same performance if they used B4 fuel. And yes they were normal 605 superchargers as they were DB 605A or DB 605AM engines (depending on wether this was factory made standard or MW 50 retrofit using previous GM-1 equipped machines as they already had the tank and plumbing system).

One common configuration we are lacking for the DB 605D is using C3 fuel for 1.8 ata without MW 50, this one would bring similar performance to the regular K-4 at a bit lighter weight (if i'm not mistaken the MW 50 set + liquid weighted almost 100 kg), with the only downside being the radiators would need to be open a bit more given the lack of cooling effect.  For example in this G-10 that landed in Sweden in May 1945, has C3 sticker but no MW 50 decal.




 

 

Edited September 1, 2022 by -=PHX=-SuperEtendard

[Kurfurst]

On 8/31/2022 at 10:33 PM, 357th_KW said:

In summary, we have a great deal of original documentation stating that 1.98 was restricted,

 

You don't. You have selectively quoted snippets, most of whose directly contradict your own theory BTW. 

 

On 8/31/2022 at 10:33 PM, 357th_KW said:

and that engines were breaking in ideal factory conditions at that power level. 

 

They weren't. The first DB memo specifically address this and notes the issues with 1.98ata / DC setting were specifically due to wrong assembly of the engines (valve seats), and the failed engines were correctly afterwards and run without issue. The whole story can be summed up with crap B-4 quality causing problems with the DB setting while the DC is okay from the beginning which is already quite clear to everyone but some in the Luftwaffe top brass are furious for being 'left out' and insist red taping the 1.98 ratings 'further testing'  for about 2 months, which then reveals that there is nothing to fix in the first place. 

 

On 8/31/2022 at 10:33 PM, 357th_KW said:

We also have evidence that production engines were struggling to even handle 1.8ata with poor quality B4 fuel in the field.

 

That much is true. As a matter of fact, the only issue was with the DB setting is due to varying quality in B4 fuel, which is addressed in February 1945 by

(i) increasing TEL content of B-4 from 0.12% to 0.16% (this increase in TEL made it's performance more or less similar to C-3), and

(ii) using less aggressive settings (reducing at manifold by 0.05 and retarding ignition) on the DB engine, which reduced max. power by cc. 50 PS. 

 

 

There were no change ever made to the DC settings because they do not need to - C-3 had no quality issues to begin with and the ruckus was caused by a few dozen badly assembled 605Ds in December 1944, which were then supplied to some testing centres and failed, causing an alarm, by which time DB has already fixed the issue.

 

On 8/31/2022 at 10:33 PM, 357th_KW said:

There is no documentation of the engines ever being cleared to run 1.98,

 

There is. It is cleared to run at 1.98ata already in the start of December 1944, after several live test runs with G-10s and K-4s. 

The DB and DC engine is the exact same, DB/DC just a name for a different MAP and fuel pump setup. 

 

They were meant to be supplied as 1.8 as a base setting and were cleared to run at 1.98 ata from the very beginning.

 

On 8/31/2022 at 10:33 PM, 357th_KW said:

or ever doing so in a production unit.

 

They did.

 

You yourself have quoted the DB 605 DB/DC repair instructions that specifically says that DC engines (i.e. 1.98ata) are being supplied in March 1945 without any change in their settings. 

 

You yourself have quoted  DB memo 6730 that specifically mentions that some frontline units are already using the DC setting (which is why the LW top brass and Rechlin is pissed off)

 

 

 

The unit involved with frontline testing, II/JG 11 also released a very lengthy experience report with the DC / 1.98ata setting which basically said having zero problems in the field, as a matter of fact the DC engines are called the 'best and most reliable engines' of the unit. 

 

On 8/31/2022 at 10:33 PM, 357th_KW said:

It's clear that the Luftwaffe wanted to do this, testing was done to try it and they wanted to do anything they could to improve the performance of late model 109s, but the evidence of operational use just isn't there.

 

It is there.

 

There is not the slightest doubt that II./JG 11  used the 1.8, interim 1.9 and 1.98 ata ratings beginning in December 1944 through February 1945. It is extremely well documented.

 

There were five other (Western) Gruppen of JG 27 (I., III) and JG 53 (I., III., IV.) that order to start using it from March 1945. You can then of course argue as much you'd like that these units were somehow incapable of setting up their engines properly for the 1.98ata rating, which was basically a flip of a switch, but somehow still managed to set up 1.75 or 1.8 or 1.9 ata on the engine. 

 

image.png

 

It's quite likely that some other wings (from JG 4 and the 101. RHAF) were using these ratings as well, from memoirs and photographs, fuel supply documents etc.. 

 

As matter of fact, when the evidence were showed to Mike Williams he worked himself so much up that he immediately removed any trace of the 1.98ata performance levels from his website, then the denial went through various iterations. My personal favourite was when he went like 'oh yeah, maybe they did, but it was just p****ing into the wind'. Nowadays its just cherry picking the fitting parts from some documents he thinks fitting, but as he doesn't quite understand German, actually its quite humorous to see how his own documents contradict him. See above. 

 

Edited January 25, 2023 by VO101Kurfurst