WEP on the C205

[VO101_Isegrim]

I guess Pyro just kicked a Hornet Nest.

As for the 1.42ata, lets only say its introduction date is highly debated.

Possible dates could be about January 1943, June 1943, automn 1943, and spring 1944. Every one these dates have supportive evidence of some sort. Personally, I tend to believe 8th of June 1943, when an official clearing was issued.

Troubles were caused by burning out piston heads.

[Pyro]

What was the fix?

[Pyro]

Not sure if that mail link is working right.  My address is dougb at hitechcreations.com.  Make sure you use a header that will unequivocally let me know it isn't spam.  If the header is blank or ambiguous, chances are the email will be deleted without being read.

[VO101_Isegrim]

Originally posted by Pyro
What was the fix?

Redesigned piston heads, but I think there were other fixes added as well. Trouble was iirc too little clearance between the head and the bore (not sure about correct tech terminus of English), and that the pistons burned out too quickly.

Keep in mind that the 605s were also used in the He 177, where in their interconnected design (610) they developed main bearing troubles, as seen in the RLM discussions, probably because of sync problems between the two engines, and the huge forces involved (3100 HP engine!). I guess this didnt effected 109s/110s much.

Third problem was non-engine related, founded in the varying quality of synthetic avgas, which could cause pre-ignition troubles, and was fixed with new type of spark plugs. No problem though when using 'natural' B-4 avgas, which was of better (or more like, more stable) quality.


Edit: I just sent an email 4 you, Pyro, at the given address. Hope you got it.

[Nashwan]

I'm curious about the 1.42 ata restriction. I've always thought that the restriction was just a teething problem on the early G-2s. If it was not fixed until '44, exactly what was the cause and fix?

I went on holiday just after I first saw Butch's comments on this, so I don't know if he's found anything other documents one way or another, but there's some reference to it in this thread at Ubi:

Isegrim since you are so fond of flight manuals, could you check your copies of the following documents :

- L.Dv.T.2109 G-12/Fl which is the Bf 109G-12 Bedienungvorschrift-Fl (Stand August 1944) Ausgabe Dezember 1944

- L.Dv.T.2109 G-4/R3, G-6/R3/Fl which is the Bf 109 G-4/R3, G-6/R3 Bedienungvorschrift-Fl (Stand November 1943) Ausgabe Februar 1944

- L.Dv.T.2109 G-2, G-4, G-6/Fl which is the Bedienungsvorschrift-Fl (Stand April 1943) Ausgabe Juni 1943

You'll notice that none of those documents, which are the actual flightmanuals btw, clear the 1.42ata boost.
The only late manual i have seen so far that cleared the DB605A 1.42 boost is the DB605A-B Baureihe 0,1 u. 2 motoren-Karte (Stand April 1944) Ausgabe Juli 1944. This document replace the Motorenkarte issued in Oktober 1942 which, contrary to the earlier motorenkarten, prevented the use of the 1.42ata boost.

There were no revision between the two MotorenKarte, but a lot of modifications were done on the DB605A design in the meantine.

http://ubbxforums.ubi.com/6/ubb.x?a=tpc&s=400102&f=63110913&m=875109873&r=452107983#452107983

Futher down:

Btw the 1.42ata boost appear in various documents of mid 1943, with the followings mentions : 1 minutes setting ! hardly convenient as a boost isn't it. And with the following mentions in the Bf 110G-2 manual : "z.Z.gesperrt" which translate by "Not currently available".
Moreover i have a list of modification introduced in Oktober 1943 so as to fix the deficiencies of the DB605A.

i don't have Butch's email, but he comes here occasionally, and I believe you've had corespondence with him in the past.

[VO101_Isegrim]

Posted by butch2k

There were three main problems with the DB605A, the last one being pre-ignition troubles when using B4 fuel at 1.42ata. It was not solved until the introduction of a new kind of sparkplug.
It seems that it was possible to run on 1.42ata but only when relying on true 87 octane fuel not the ertsatz B4. So it might explain why some aircraft could actually use 1.42ata by mid 43. [/u]

As in fact they did even a bit earlier on :



British report of Bf 109G-2/trop dated 8th February, 1943.

Another point of interest is the very economical fuel consumption even when high powers are involved (Merlin 66 consumed 150 gal/hour at WEP).

[Pyro]

If that extract is from the British report on the G-2 trop they captured and tested, that's originally how I came about the thought that the restriction was just an early teething problem with the 605.

[mw]

Hi Pyro:  here's some excerpts from docs I have:

•   Flugzeugmuster BF 109 G-1 mit motor DB 605A Kennblatt:
The figures indicated refer to combat and climbing power. n - 2600 U/min:Plade - 1,3 ata. Take-off and emergency power are not as yet approved for the 605/A. Die angegebenen Leistungen beziehen sich auf kampf und steigleistung. n - 2600 U/min :Plade - 1.3 ata. Start und notleistung ist für 605/A zurzeit noch nicht freigegeben

•   R.L.M. message GL/C-TT No.1374/42/42 of 12.6.42 as translated by British Air Intellegence.
A number of cases of breakdown in the DB 605 engine as a result of pistons burning through have occured. The following must therefore be observed.
The Take-off and emergency output with a boost pressure of 1.42 atm. and 2800 revs. may not at present by used. The climbing and combat output with 1.3 atm. and 2600 revs. may in the case of the older engines (for works numbers see below), be used only when operationally essential.

•   Bf109 G-2 Bedienungsvorschrift-F1 Stand Juli 1942
*Note! "start and emergency power" is blocked and may not be used. *Achtung! Die "Start und notleistung" darf nicht benutzt werden, sie ist deshalb blockiert.

•   DB 605 Moteren-Karte 9 October 1942
Take-off and emergency power is closed up to revocation , thus 2650 U/min (2600 U/min +2%) may not be exceeded in any flight attitude. Die Start und Notleistung ist bis auf Widerruf gesperrt, es dürfen somit 2650 U/min (2600 U/min +2%) in keiner Fluglage überschritten werden.

•   From 109 G1, G2 and G6 Meßrief - 1942 and 1943
Take off and emergency power: Provisionally closed after VT instruction Nr.2206. Start und Notleistung: Vorläufig gesperrt nach VT-Anweisung Nr.2206

•   Meßrief BF 109 G-2 trop 10798
           Start und Notleistung:  Vorläufig gesperrt nach VT-Anweisung Nr.2206
           14.12.42


•   Meßrief BF 109 G-6/tp Wk Nr 16387
           Start und Notleistung:  Vorläufig gesperrt nach VT-Anweisung Nr.2206
           Vorläufige Fluggenehmigung 9.März 1943


•   Meßrief BF109G-6/tp Wk Nr 15218
           Start und Notleistung:  Vorläufig gesperrt nach VT-Anweisung Nr.2206
           Abnahmeflug  acceptance flight  18.3.1943

•   Meßrief Bf 109 G-6 trop 16647
           Start und Notleistung:  Vorläufig gesperrt nach VT-Anweisung Nr.2206
           Sonderladeplan 8.4.43

•   BF 109 G-6 Wr Nr 18421 data card showing 1.3/2600 limit

•   Trials Reports of Bf 109 G showing 1.3/2600 as the engine limitation
           Nr 109 19 L 42 (19.9.42)
           Nr 19 20 L 43 (22.1.44)
           Nr 1018105428 10.5.44

•              Technishe Daten Bf 109 C, D, E, F, G
Steig und Kampfleistung: zugleich startleistung
November 1943

[GScholz]

Yeah and make sure you read mw's "work in progress" too.

http://www.fourthfightergroup.com/eagles/spit9v109g.html

Titled: Rewriting history "How the Spitfire ruled the skies", by Mike Williams.

[Angus]

but...the Spit did rule the skies, right

[MiloMorai]

Originally posted by Angus
but...the Spit did rule the skies, right

For sure, for just like teeth in a chicken's mouth, Messicraps were hard to find. The Spit, with some help, had driven the Messicraps from the sky.

[MiloMorai]

Originally posted by GScholz
Yeah and make sure you read mw's "work in progress" too.

http://www.fourthfightergroup.com/eagles/spit9v109g.html

Titled: Rewriting history "How the Spitfire ruled the skies", by Mike Williams.

And what is wrong with mw's work? He is comparing 1942-43 Spitfires and Messicraps.

There is also a line saying that the performance of later a/c increased.

[Angus]

Hmm, true, those charts are basically comparing planes in a certain timeframe. Rather the operable planes it looks.

[VO101_Isegrim]

Ever wondered why Mike`s references suddenly end in the spring of 1943 ?



From Radinger-Otto : Me 109F-K, The world`s most produced fighter.

Of course he lists Spits on their 1943 boost, and hand picked worst performer  109Gs on their 1942 boost.

But what would you expect from Mike if not that?

BTW, as per the performance of 109G-2 in AHT, it runs at 1.3ata boost with WEP, ie. the 1942 standup.

1.3ata / 2600rpm was sustainable for 30 mins, so the WEP time should be corrected accordingly.

[FTJR]

So..... I guess that means I cant have more wep on my 205:eek: