Garuda propeller

[gino]

Hi

I have this Garuda Propeller with following inscriptions:

GARUDA
PROPELLER
D.R.P.
NR 3222

100 PS
MERCEDES. 6 CYL
D 270 BLATTER 025
STG 140

GEPRUFT
FLERS ABT2

STAND
1270

GEPRUFT
P&W



Here my questions:
What is FLERS ABT2 ?
What are the small stamps (cross) on picture 5 ?
Which airplane type ?
Are those metal hub plates original ?

thanks
Best regards
Gino

[gino]

some more pictures

[gino]

and more pictures

[Dave]

Nice prop and decals. What is the measured length from tip to tip?

[gino]

Measured lenght is 270 cm.

Gino

[Dave]

I think maybe you need to remove the metal hub assembly to get a good look at the wooden part of the hub. I'm not sure what's beneath it on this picture.



Usually the holes in the plate cover wood completely, but you can see a bevel underneath this one, and it looks as if the wood has been painted beneath the holes as well.

It's a very nice looking prop!

[Bob Gardner]

'Morning Gino,

Answers in red. I've translated all the data for the benefit of other forumites.

GARUDA PROPELLER Formed in 1910 in the Neukölln suburb of Berlin
D.R.P. Deutsche Reichspatent. The German system of registering patents in use from 1871 to 1945.
NR 3222 serial number

100 PS MERCEDES. 6 CYL 100hp Mercedes engine. 6 CYL indicates it was made shortly after Mercedes added two more cylinders to its four cylinder 70hp engine.
D 270 Durchmesser - diameter in cm
BLATTER 025 Blattbreite, blade width, a term found on Garuda propellers as in BLATTBR 028 indicating a blade width of 28cms.
STG 140 Steigung pitch

GEPRUFT Found to be airworthy
FLERS ABT2 Flieger Ersatz Abteilung Flyers Replacement Division. Rarely seen. I have only seen this stamp once before, on an early Heine prop. Perhaps this training organisation did its own proofing until superceded by P & W in 1915? (Prüfanstalt und Werft der Fliegertruppe the Test Institute and Hangar (or workshops) of the Flying Troops.) I would welcome some elucidation!

STAND 1270 Abbreviation Standdrehzahl test engine speed. Translates as the Condition Speed, a parameter the propeller had to achieve.

GEPRUFT Found to be airworthy
P&W Prüfanstalt und Werft der Fliegertruppe the Test Institute and Hangar (or workshops) of the Flying Troops. It combined to form the FLZ in 1917 so P & W on a propeller dates it to 1915 to 1917.

Here my questions:
What is FLERS ABT2 ? See above
What are the small stamps (cross) on picture 5 ? I don't know
Which airplane type ? Alb B1, Ru Taube
Are those metal hub plates original ? Probably

With kind regards,

Bob

[Bob Gardner]

Gino,

Last night I finished my book on German makers from Adastra to Garuda. Your photographs came just in time. May I include them in the book?

With kind regards,

Bob

[gino]

Hi
Thanks Bob and Dave for your help.
Of course Bob, you can use those photo's for your book.
If you need some better pictures or different size, let me know and
I ll send them to your personal mail adress.
I am trying to remove the metal hub plates but seems to be not
very easy. I have removed the bolts and the ensemble seems
to be loose now but I not able to split the back plate from the front
plate.Are they screewed or are the pressed together?
best regards
Gino

[Bob Gardner]

Thanks Gino,

Congratulations on finding this wonderful prop.

I would be grateful if you could send me photographs. Do you have my email address? Please send the photographs at about 1mb (or bigger). This will enable me to put large photos in my book.

I advise not doing any more to the hub plate. German ones can be extremely difficult to remove. I know of a marvellous Fok D VII prop except for the hub, where it looks as though someone has used a crowbar or perhaps has hammered steel wedges between the wood and metal. Your prop is better left untouched. And I think the metal hub to be genuine. (If it came off easily it wouldn't be genuine!). I have photographs of similar hub plates, although not exactly so, on Garuda props.

With kind regards,

Bob

[dairwin]

Are they screewed or are the pressed together?

If the assembly is like the Watts hub, then the front plate will have a spline that passes over an internal spline attached to the rear hub. The interface may well be corroded together.

I recommend taking Bob's advice, and not trying to separate.

DAI

[gino]

Hi
Indeed, I also think it is better not to try to remove
de metal assembly, so I will leave it the way it is
right now. The black paint seems to be added from
outside, so the wood below the metal plates have not
been affected.I think the metal assembly is original
and contributes to the history of this propeller.
Bob .... I am out of the country for a few days but
will send you the photographs latest on friday.
One more question: should I apply bee wax from
a tin to conserve the propeller or not touch at all?
Thank you all for your help and advise.
Gino

[Bob Gardner]

Many thanks Gino.

Beeswax is always a good idea.

First clean the prop very gently with a damp cloth. Start on a small part of the prop which is generally out of sight, as a trial. If the damp cloth lifts a lot of dirt, continue, perhaps with a drop of washing-up liquid to act as a de-greaser. Be careful. The blades have contraction cracks. Don't let the cloth catch any edges. Also note that you don't know what the previous owner might have done to the prop. Don't flood the prop with water.

Let the prop dry for a day.

Then apply the bees wax. This must be pure bees wax polish without any modern additives such as silicones which can cause the surface to bloom. This will cause a grey-white sheen to form, which will be dreadful. Again, experiment first on the same small part as last time, as a trial.

If you are happy with the trial, apply the bees wax in small amounts, perhaps the size of your hand, and polish.

If you have the slightest worry, stop immediately.

Most people find that careful cleaning and waxing transforms their prop.

Your prop needs to be in a room of some humidity. Central heating dries woods and they crack. The humidity should be more than 65%. You can buy a hygrometer from a garden centre for a few Euros. If necessary put a small container of water on top of a radiator to increase humidity.

And finally don't hang the prop near a source of heat or in the sun.

Proceed with care.

Take some before and after photographs for us to see.

With kind regards,

Bob

[pmdec]

Hi all,

There are very interesting facts about relative humidity from a Canadian Institute. Cerise sur le gâteau, they are published in English and in French:


Pages of special interest about relative humidity there :
http://www.cci-icc.gc.ca/caringfor-p...hap10-eng.aspx

I think that propellers could be cared as wood assemblies.

Below is a personal advice, without any proof nor true study:

Un autre son de cloche (another story) about beewax and propellers: IMHO, never apply anything containing "fat" on a propeller which has its original varnish (or part of it). The "fat" will slowly sink into the wood through small cracks, darkening wood color and easing original varnish to unstick. It could take years, but it will.

Regards,
PM

PS: I don't think metallic hub is an original one for this prop because, as Dave suggested, it not fits well. But hubs of this age (100 HP Mercedes became usual in the middle of 1913) are not well known. Try to find a picture where the number of bolts is visible (six are rarely seen on engines after 1912, except on small ones, and 100HP is not so small!).

[gino]

Hi
As far as I know, 6 bolt holes are standard for
the mercedes d1 100 hp engine!
Gino