Another album-find

[rhwinter]

Sorry, but I had to post this! Absolutely sharp pics:

http://www.ebay.de/itm/Album-Flieger-Abt-19-Frankreich-VERDUN-Flugzeuge-Luftbilder-usw-142-Fotos/261881252315?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D31092%26meid%3Dfbb7ad495f4c48ea96b718c7900e85b1%26pid%3D100009%26rk%3D7%26rkt%3D10%26sd%3D381256063722

(No affiliation with the seller, though..)

[bobs_buckles]

Excellent - Thank you 
vB

[Dave in Dubai]

Interesting photograph which raises an interesting question:

The  cylinder pots do not appear to have the black finish commonly seen on other machines.

Does anyone know whether the black finish was always applied?

I saw a Mercedes aero engine in Vienna a few months back which looked like it was in an original condition, and there was no black apllied- the cylinder walls were all natural metal but appeared to have a burned on coating of a brown oil on them.

Thanks if anyone can explain what the situation is.

[uncletony]

Hmmm the cylinders were steel, with welded steel water jackets so some kind of protective finish (I.e paint) would be mandatory to provent corrosion -- nothing like heating and cooling cycles+ exposure to the elements to get that going. (Statements of the obvious, I know)

I think the cylinders in the photo are painted black, just reflecting light differently. But, maybe not. There are museum examples with the pots painted brown and green, but no clue whether this is just someone's fantasy.

Another thought is that a mechanic could paint them any color he might have had on hand after a rebuild...

[Pgtaylorart]

I think they could be black like you said, Bo, just reflecting the light. It's more about specularity than color in these old B&W photos.

George

[Dave in Dubai]

Hi guys,

I wondered whether it was the sunlight too, but the cylinders moving aft look  to be lighter too, even though they seem to be in shadow, hence I wondered whether they were actually black?

[uncletony]

Hmmmmm maybe you are really on to something Dave…

look at the (painted? metal) whatsits in th bg of this photo, compared with the jackets



and here, look at the difference between the cylinders and the breather pipes:



Hmmmmmmmmmmmmmmm………..

[Pgtaylorart]

Good photos, Bo. Pretty convincing evidence that they were not always black. But then what color?

[Ian from Doncaster]

Could be bare steel?  or with a thin protective layer of paint, looking like gunmetal??

[uncletony]

I don't think they are bare steel -- the discoloration and marks from the welding would be highly visible. Check the great TVAL Mercedes resto photos to see what I mean...

[Dave in Dubai]

Great photos Bo, thanks very much.

Maybe they were just left in metal and coated with some sort of protective oil?

It wouldn't take long for this to burn onto the cylinders leaving a sort of protective coat, a bit like you see on well used engines on RC model aircraft.

The service life wasn't too long so maybe corrosion was not a primary consideration?

What got me thinking was the original picture at the start of the thread, coupled with an original Merc displayed in The Arsenal in Vienna. I have no idea whether the engine has ever been touched, but from it's appearance the whole engiine looked well used and the cylinders were covered with what looked like a burnt oil covering.

Next time I go, I will take some pictures.

[uncletony]

here is what I was talking about -- the jacket shows scorch marks where it was welded, and the different types of steel (forged liner, stamped sheet jacket) have very different specular qualities. I think these traits would still be quite visible thru any transparent coating. Therefore I think they were painted with opaque paint.



Simply covered with oil, the sheet steel jackets would certainly start to corrode almost immediate at least around the exhaust ports where it would get very hot and any kind of oil covering would quickly burn off. Plus I think that would be quite the fire hazard!

Anyway, that's my $.02....