Meaning of AS in DB605 AS

[D.B. Andrus]

Does the "A" designate the variant of 605 motor and "S" stand for Sonder(Special)?


Thanks in advance.


Cheers,
D.B.

[schwarze-man]

Hi DB,
The DB605AS is indeed a version of the DB605A motor. This is defined in the partslist for the 605AS and is shown by the fact that, that partslist only covers the different parts that are needed to build a 605AS from a 605A. I have not found an original German document that defines the abbreviation as "DB605ASonder". Cheers

SM

[D.B. Andrus]

Thanks, SM.

[schwarze-man]

Hi again DB, It is interesting exactly what the S did stand for? Of course, your question about "Sonder" is valid but, I have not seen any original description for that meaning. It is also interesting how the later changes to the 605AS seem to have been incorporated. The addition of Water-Methanol injection MW50 (starting around May '44) was followed by the addition of the M suffix to give 605ASM. This was similarly matched by the same suffix to MW50 equipped 605AM and 605DM. By December '44 the 605DM was superceeded by the 605DB and DC, where the "M" suffix was dropped, although the engines were fitted with the equipment. Similarly, the early '45 605ASB and ASC appeared, also equipped with MW50 but not with an "M" suffix, although some modern writers have sometimes added one. Cheers

SM

[Kurfürst]

Hello guys,

The thing I am wondering about is if anyone knows what was the historic rationale behind the AS development. Or in other words, what drove its development specifically and when did it start? When was the decision made to develop such an engine and what was cited to as a reason for it?

I am looking for specific answers, we all know that the AS series are basically the 605A equipped with the 603A's supercharger, that the first live engines were running in prototype 109Gs by September 1943, and that the type saw production by December 1943, service by April 1944 the latest; which appears to be more of a lucky coincidence with the appearance of Merlin Mustangs than a conscious process, given that development and testing must have started well before any Mustang appeared, presumably spring-summer of 1943 already, and any of two stage Spits were also preciously few in numbers at that time as well.

So the question I am asking is what was going on in the management of the RLM. What was it was meant for - high altitude recce interceptor instead of the GM1 subtypes, an answer for high flying B-17s etc.?

[schwarze-man]

This got me thinking and I have done some research of my data. Perhaps surprisingly, there does not seem to be any explanation about the "S" letter of the DB605AS designation in the AS documentation that I have. The usual description is the simple phrase "the DB605AS is the DB605A fitted with the larger supercharger from the DB603". Specifically, the supercharger is similar to the one from the 603A, the 603 also coming in later versions with it's own even larger supercharger(s), including a 603AS version.
Now, in documentation of DB engine developments, I notice that the term "Super Lader" being used for developments of their superchargers. The Germans refer to the supercharger unit as the "Lader", so the term Super-Lader is quite satisfactory and, I think that it is possible that the development of the DB605A with the larger "Super-Lader" would be termed the DB605AS. Cheers

SM

[Snautzer]

perhaps s from schleudergebläse ?

[schwarze-man]

Originally Posted by Snautzer

perhaps s from schleudergebläse ?

No, where do you find that term please Snautzer? The term Super Lader comes specifically in original DB605 related Lader development papers and, I am fairly confident now that this term is the origin of the AS designation in those 605 and 603 types that reached production. Cheers

SM

[schwarze-man]

Hi Kurfurst!
I am certain that the search for improved high altitude performance from the DB605 led to the development of the DB605AS which, in its original form without MW, was only offering better power than the DB605A above its rated altitude and actually less power below due to increase power to drive the Lader, increased heating of the charge air and the same 1.42ata limit. Worth noting that the RR Merlin 60 series engines with two speed-two stage supercharging with intercooling had begun powering the Spitfire Mk IX on production from Jun '42 and these had a 40,000 feet / 13+ km altitude operating ability. Cheers

SM

[Snautzer]

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