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Old 11-18-2013, 03:11 PM   #11
dairwin
 
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Quote:
Originally Posted by gino View Post
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
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Old 11-18-2013, 06:59 PM   #12
gino
 
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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
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Old 11-19-2013, 05:25 AM   #13
Bob Gardner
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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
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Old 11-19-2013, 03:19 PM   #14
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Hi all,

There are very interesting facts about relative humidity from a Canadian Institute. Cerise sur le gāteau, 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!).
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Old 11-19-2013, 05:36 PM   #15
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Hi
As far as I know, 6 bolt holes are standard for
the mercedes d1 100 hp engine!
Gino
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Old 11-19-2013, 06:48 PM   #16
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Hi Gino,

If late Mercedes 100 HP also used a six bolts hub, it is not a way to give a date for your prop
I am conviced it is a very early one from two facts:
- the markings are complete but also very neat: on one GEPRUFT, there is the umlaut impressed (two dashes inside the upper part of the U),
- from the pitch (140 [centimeters] and the engine speed [1200rpm, 1270 max], the "geometrical" aircraft speed is only ~100km/h, that is about a 90 km/h (56 mph), a very low one.

But perhaps Bob could tell something about that from the prop number? Could it be a prewar prop with a second airworthy marking later (and perhaps a refitting with a new decal at this date)?

Anyway, a very rare and interesting prop!

Regards,
PM

EDIT: http://www.aeroconservancy.com/barographpaper.htm
Il you magnify the page (Ctrl + +), the prop (and the metallic hub!) look very like yours on a LVG.

Last edited by pmdec; 11-19-2013 at 07:39 PM. Reason: Add link
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Old 11-20-2013, 10:13 AM   #17
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I have several hub photos of German prop hubs and this one looks much the same as the others. Six bolt-holes existed on German aero-engines in 1914 and probably early 1915. Some German hub plates do have lightening discs cut in a way that reveals part of the hub aperture. So I believe this hub plate is original to the prop and beyond doubt it is of German design.

Garuda serial numbers that I have recorded, run from the 1200's to the 23,000's. These date from 1911 to 1919. So my guess is that 3222 dates from c1914 to mid 1915.

There is a trap that I fall into every now and then. I find a propeller dating from 1918 with six bolt-holes which I initially think must be wrong in some way. But a 1915 Alb B II with a 100ps engine might well be flying only three years later in 1918 as a training machine or squadron hack etc. and be in need of a replacement prop.

PM. Cerise sur le gāteau The cherry on the cake. I understand the idiom but what does this Canadian Institute regard as the cherry on its cake?

I met bees wax when I was a dealer in clocks, particularly long-case clocks (commonly called grand-father clocks). Furniture dealers brought bees wax to my notice. It is very widely used on both new and old finishes throughout the antique trade in Britain and has been in use for centuries. So, I think it is safe to use. But care must be used because it might react with something the previous owner used on the prop. Hence my advice to always try a small portion on some small insignificant part of the prop; and not to use a modern aerosol version which has added silicates which often react with old finishes.

With kind regards,

Bob
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Old 11-20-2013, 12:39 PM   #18
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Hi
The previous owner of the propeller was a gunner(ground) during WW2.
He found this propeller at his base close to Monchen Gladbach during
that periode and brought it home as a souvenir the way it is right now,
including the metal hub. This is also the reason why I think that
it is still the original one.
I decided not to remove the plates and leave it the way it is. Looks nice
with the metal hub anyway.
I also think not to touch the propeller at the moment because it looks
fantastic and think waxing is not required at the moment.
If I decide to treat the propeller later, I will use the bees wax as recommended
by Bob. Soon or later, wood has to be treated one day and there seems
to be not many options were bees wax should be probably the best choice.
Thank you all for your inputs on this one,



Best regards
Gino
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Old 11-20-2013, 04:02 PM   #19
pmdec
 
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Quote:
Originally Posted by Bob Gardner View Post
.../...
PM. Cerise sur le gāteau The cherry on the cake. I understand the idiom but what does this Canadian Institute regard as the cherry on its cake?
.../...
With kind regards,

Bob
Hi Bob, the cherry is just that the entire site is in English and French. The site gives, IMHO, very appropriate advices about relative humidity and temperature considerations for the best conservation for different kind of artifacts, with statistics, not only general considerations. This is not very easy to find such advice outside "antiquarian world" (which have too often only an appearance goal).

Regards,
PM
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Old 11-20-2013, 04:51 PM   #20
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Oh Yes. I see. I misunderstood.

Bob
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