Bf 109 identity

[olefebvre]

Harri,

Indeed the ASC required C3 but i was just tackling the AS(M) issue not the ASB/ASC series. Those were introduced at about the same time as the DB605DB/DC were. They were upgraded ASMs put to DB/DC standard, and yes the ASC indeed required C3 but those were not cleared for use until early 45 as underlined by T-AMT docs, a date which is not too compatible with the picture and the Werknummer.

There were 350 (IIRC) conversion kits issued early 44 for conversion of 109G/U2s using GM-1 to MW-50 use. The a/c retained the old insulated GM-1 tank, had several parts replaced and the DB605AM or ASM fitted. As described in the early DB605ASM docs, this engine required C3 when initialy introduced. Order was later relaxed, with B4 being tolerated provided the boost was not used without MW-50. This relaxation occured late summer 44.
Information solely based on DB, Mtt and RLM docs.

Cheers,
olivier

Originally Posted by Harri Pihl

Olivier,
There were several different variants of the DB 605AS engines.

The first produced DB 605AS versions were simply conversions of the DB 605A and retained 1:7,3/7,5 compression ratio and were for B4 fuel. The G-6/AS planes of the Finnish air force had these engines.

After initial conversion engines the early produced version of the DB 605AS had higher compression ratio (1:8,3/8,5) and required C3 fuel even if not setup for MW50, these engines are sometimes called as the DB 605ASC.

Later there were many other versions called ASB, ASM etc. some required C3 and/or MW50, some B4, some could use both fuels. But these probably came too late for G-5 or G-6 as seen in the picture.

Sources are Valtonen's article in the SIHL and various DB documentation.

Regarding the plane in the picture; it seem to be a G-5 or G-6 (according to Wnr), it's also probably a AS (tall tail, light grey camouflage) and the C3 triangle means that it had a DB 605AS with CR 1:8,3/8,5 and/or MW50. Time frame for such variant might be something like summer 1944.

[Harri Pihl]

Olivier,
I'm just saying that early DB 605AS engines with 1:8,3/8,5 compression ratio required initially C3 fuel regardless if there was MW50 (DB 605ASM) or not (designation unknown to me, probably still DB 605AS). That is why I wrote "these engines are sometimes called as the DB 605ASC" despite that designation came later. There are pictures of such planes and the point is that C3 triangle does not mean that there was MW50 in the plane.

Generally it's one thing what the specifications say and what was planned to produce but it's whole another thing what really came out of production lines or repairing centres.

[olefebvre]

Do you have an idea when those early AS(C) engines with high CR were delivered ? Or reference to a document ?
Cause every DB605AS stuff i have seen so far show no need for C3 (even in the various manuals and datasheets). The only case were i have seen C3 mentionned is with the early ASM engine and that's with the low CR.

[Harri Pihl]

Olivier,
I don't know any dates. According to Valtonen (he refers some sort of LW memo) it was planned to switch to higher CR after a small serie of lower CR engines but in reality there certainly was quite large number of low CR engines (the Finnish air force AS planes with lower CR engines were delivered summer 1944). Most probably there were several versions of AS engines (high and low CR etc.) in production same time depending on manufacturer.

Generally it's difficult find exact documentation on these because there is quite a lot confusing documentation. So in practice pictorial evidence seem to give most reliable view.