1.98ata testing

[Kutscha]

What unit(s) field tested 1.98ata and were other Bf109s besides the K-4 used in the testing?

The dates for this testing would also be appreciated.

[harrison987]

Evidence shows it was 100% installed and used in the Fw190D9 and Me109 G10/K4...but don't know of any field testing that was done.

[Kutscha]

Thanks Harrison. Are you sure about the D-9? Seems to be a strange boost level for a Jumo.

Further searching I found that 'Gruppe 2/JG11' did some operational field testing before being cleared for operational use. That is a strange designation as 2 would be a staffel number and the gruppe designation should be II.

[Charles Bavarois]

It was II. Gruppe JG 11 you're talking about, which was at Wunstorf from October to 17th December 1944 for R&R. It was nearly completely refitted with new Bf 109 G-14 AS.

BTW: The test was with 1.9 ata, not with 1.98 ata.

Carl

[Kutscha]

Thank you Charles.

Sometime in Dec '44, II./JG11 got 12 K-4s.

Have you seen Umrüstnummer 63253 vom 16.1.1945?

Were the Bf109G-14/AS a/c used in testing 1.9ata?

[Charles Bavarois]

Hello Kutscha,

in a Daimler-Benz document dated 10th Oct. 1944, filed after a meeting at the “Entwicklungskommission Flugzeuge und Flugmotoren” on 3rd and 4th of October they remarked:

“Es wird beschlossen, dass die Umstellung der zurzeit in Wunstorf befindlichen 70 Motoren DB 605 ASM durchgeführt wird, wobei der bei diesen Motoren mögliche maximale Ladedruck von ca. 1,9 eingestellt wird, der dann ca. 1900 PS Leistung ergibt“. Roughly translated like „We decide, that the changes (for higher boost) will be done with the 70 engines DB 605 ASM, currently at Wunstorf. The boost for this engines is to be set at around 1.9 ata maximum, which will make around 1.900 PS output.”

I think, this makes it quite clear, that the testing of higher boost on unit-level was with Bf 109 G-14 AS and not on K-4s. BTW: II./JG 11 got its K-4 only after 20th Dec. 1944, having mainly G-14 AS and 2 G-6 in early December.

Testing at the manufacturer continued of course: Daimler-Benz weekly report dated 28. Nov. 1944 lists a Bf 109 K-4 WNr. 330.103 with DB 605 D and a Bf 109 G-10, WNr. 490.128 with DB 605 D on
tests with MW 50 and 1.98 ata Aufladung.


Greeting
Carl

[Dan History]

Originally Posted by Charles Bavarois

the testing of higher boost on unit-level was with Bf 109 G-14 AS and not on K-4s.

Carl,

Let me thank you, as an interested reader of this discussion from its beginning, for sharing excellent information.

Do you happen to know whether Bf 109s with 1.9 or 1.98 ata boost were employed on the Eastern front? I assume that they were, at least in limited numbers, after the transfer of many units to the East in the middle of January 1945, but I have no primary source information about this.

You have a private message.

Kind regards,

Dan

[Charles Bavarois]

Hello Dan,

DB 605 AS or D engines with 1.98 ata boost are still a mystery.

Firstly I think that 1.9 ata was only used for testing at II/JG 11 to minimize engine troubles.

We know, that a DB 605 AS or D was able to run at both 1.8 or 1.98 boost and could easily change from one to the other. But we lack information on the amout of actual frontline use of 1.98 “superengines”. IMHO very few Bf 109 were runing on 1.98 and only during the very last weeks of the war.
The last hard evidence I have is a DB-document dated 24. Jan. 1945 remarking that “all four engines with 1.98 ata boost at Rechlin have been wrecked during tests. E-Stelle Rechlin has therefore not cleared the DB 605 DC. It was decided zu keep on runing the tests with Jagdgruppe 2/11 (which is II/JG 11) to get more information. Other fronline unit should not be run with 1.98 ata.” So at the end of January 1945 1.98 ata boost was not clear for the frontline-units.
Other documents from Luftwaffenführungsstab may be a hint that at least in March 1945 the problems were solved. A very few Jagdgrupen – all fighting in the West – were to be eqpipped with 1.98 boosted Messerschmitts. Among them were were JG 27 and JG 53 which would need the extra power for fighting against high-performance British and US-american fighters at moderat hights (remember: fighting the US-bombers and their escort with German piston-engined fighters had no priority any more).
What might be most important is gas. 1.98 ata could only be obtained with C3-gas and MW-50, 1.8 ata was available using plain C3 or B4 with MW-50. Germany had nearly exhausted its aviation-fuel in 1945. Producing C3 was much more elaborate than B4 and thus C3 was very limited. Even if all Bf 109 AS/D could be boosted to 1.98, there simply was not enough gas for all of them.
On the Ostfront the situation was even worse. The SU ground troops were driving staight into Germany and the Luftwaffe desperatly tried to counter with their Schlachtgruppen. Schlachtflieger flew a lot more than Jagdflieger. And they were equipped with Fw 190 which ran on C3 only. Thus what was left on C3 was needed at the SGs. What 1.98 ata a/c were transfered to the Ostfront in early 1945 may have to change to 1.8 quickly. I don’t think, that many Messerschmitts in the east were able to get C3 for runing 1.98 boost.

PS: Kutscha. Could you tellme, what “Umrüstnummer 63253” is?

Carl

[Dan History]

Originally Posted by Charles Bavarois

We know, that a DB 605 AS or D was able to run at both 1.8 or 1.98 boost and could easily change from one to the other. But we lack information on the amout of actual frontline use of 1.98 “superengines”. IMHO very few Bf 109 were runing on 1.98 and only during the very last weeks of the war.
...

PS: Kutscha. Could you tellme, what “Umrüstnummer 63253” is?

Thank you for summarising the available information, Carl. It is clear that the aircraft with engines running at 1.98 ata were rare. Your remark, that the priority at this time would have been air combat at medium altitudes, is very useful. It would have been relatively sensible to attempt to match the performance of Sptifires and Mustangs at medium altitudes, rather than at higher altitudes, where the Merlin's two-stage supercharger would probably have provided much more consistent performance than the German engines in any case.

Your hypothesis that the Schlachtgruppen in the East consumed almost all available C3 fuel, and therefore it was impossible to use 1.98 ata boost on on Bf 109s, appears well founded to me. There is also the additional consideration that from January, several Fw 190 fighter groups were also transferred to the East, leaving even less C3 available for Bf 109 units. Another, peripheral set of consumers of C3 were the Ju 88 G-1 night fighters of NJG 100.

The document with the title 'Umrüstnummer 63253' was mentioned by the Hungarian Bf 109 enthusiast 'Kurfürst' a week ago on another forum, see https://forum.il2sturmovik.com/topic...n-bodenplatte/

Kind regards,

Dan

[Kutscha]

Carl, I will quote from the link,

II. / JG 11 was ordered to do trials of 1.98ata by Umrüstnummer 63253 vom 16.1.1945. II / JG 11 performed the operational trials with 1.98ata and had reported in February 1945 that it had converted 11 of its G-14s, G-10s and K-4s to 1.98 ata (i.e. note that by this time also ASM engines of the G-14/AS had this 1.98ata rating, so basically all 109s with high altitude engines) and had not much trouble with it, with two engines failing in unrelated conditions in normal flight conditions, otherwise the spark plugs were also OK.

Thank you again for sharing your unbiased knowledge.