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Old 01-02-2013, 07:54 PM   #11
pmdec
 
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Hi,

Sommer biplanes were derivated from Farman ones. And yes, they have "sandwich" propellers (I do like the word!). You can see a Farman with this kind of assembly there: http://www.flightglobal.com/pdfarchi...0-%200639.html and on the next page ( http://www.flightglobal.com/pdfarchi...0-%200640.html ), you have even the propeller diameter which is ... 2m60 (8'6")!!! That is the same the props I know about (dimensions given in my previous post) which are "Rapid" propellers Sommer used on his aircrafts along with Chauvière ones.

In an other Flight page: http://www.flightglobal.com/pdfarchi...0-%200785.html (bottom right) continued on http://www.flightglobal.com/pdfarchi...0-%200786.html there is some arguments about this kind of fitting.

So, if the prop is bolted on the crankcase, which has a x7 symetry, it could be logical this crankcase has 7 fitting devices for the prop. But... It seems very difficult to find a picture showing this because the hub his masked by the engine supports. The only way, except finding a propeller picture from this era, would be to find a blueprint of such an engine..

And there is ever the "problem" of your "7.40" marking: ??? I am curious to see it!

PM

Small bonus: http://www.flightglobal.com/pdfarchi...0-%200076.html (Sommer aircraft drawing with sandwiched propeller).

Poker bonus to come: found picture of a Rapid propeller with 7 (seven) bolt holes, 14cm center hole and 7cm thick hub prop for Farman or Sommer with 50HP Gnome!!! Will show my cards as soon as I see yours...

Last edited by pmdec; 01-02-2013 at 08:36 PM. Reason: Bonuses
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Old 01-03-2013, 04:25 PM   #12
Dave Burnett
 
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Default Odd 7-bolt Chauviere Prop

I am excited now. The teaser is fair enough so here is another. The photos are in the camera. I am not part of the electronics age so it will require a quiet time for me to transfer and edit them. The hand engraved marking turned out to be impossible to capture with an indoor flash but I did examine it very carefully. To me it best reads 2.60 X 7.40 but I could be convinced that it reads 2.60 X 1.40 if that makes more sense.

I did take out an atlas to see if I could find the fishing port of Arendal, Norway and there it is near the southern tip of that country. It is a long way from France and I don't believe that a French pilot would fly that far even with a lot of brandy beforehand. Germany and Denmark would be better candidates along with Norway itself. Do you think that the prop may be a German manufactured knock-off or copy for use on an aircraft of obvious French design?

Maybe if my luck continues some sharp eyed forum member might even be able to find a matching aviation death early in the war?
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Old 01-03-2013, 06:20 PM   #13
pmdec
 
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Hi,

If you have difficulties to transfer the pictures, you can send them to my mailbox (pmdecombeix at yahoo dot com) and I will post them from a server. Don't use the flash. Light coming from the side is the better to capture the markings (try different placing relativly to light source).
Chauvière had a licensed maker in Germany before WW1. The Chauvière decal (see http://www.woodenpropeller.com/image...rtXXIVdec1.jpg ) read "INTÉGRALE- BSGDG - PATENT - DRP". BSGDG is for France patent (Breveté Sans Garantie Du Gouvernement), PATENT for England and DRP for Germany (Deutsch Reich Patentiert).

PM
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Old 01-03-2013, 10:37 PM   #14
Dave Burnett
 
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Default Odd 7-bolt Chauviere Prop

Pictures are now transferred to my computer. I will send some full size ones to PM later. I will try to send some size reduced ones as samples.
Attached Images
File Type: jpg backofprop.jpg (71.4 KB, 10 views)
File Type: jpg backtipprop.jpg (76.5 KB, 13 views)
File Type: jpg bladefront.jpg (50.8 KB, 10 views)
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Old 01-04-2013, 01:52 PM   #15
Dave
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Interesting . . .

(BTW, may I suggest taking a few moments to understand the rather straightforward method of processing photos to post on the internet using Irfanview, which is a free, very popular photo imaging software package. See this post for details. It can be very handy, not just here but in a variety of other circumstances as well.)
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Old 01-04-2013, 02:21 PM   #16
Dave Burnett
 
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Default Odd 7-bolt Chauviere Prop

Three more photos: hubfront, leftfront, and failed photo of engraved markings. Only long side view remaining.
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File Type: jpg hubfront.jpg (75.9 KB, 10 views)
File Type: jpg leftfrontprop.jpg (37.0 KB, 8 views)
File Type: jpg Propengraved.jpg (66.9 KB, 8 views)
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Old 01-04-2013, 03:46 PM   #17
pmdec
 
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Quote:
Originally Posted by Dave Burnett View Post
Three more photos: hubfront, leftfront, and failed photo of engraved markings. Only long side view remaining.
Waooh! It is a true treasure you have! I will come back later as I have kind of "administrative" stuff to do before tomorow morning.
Will come with pictures:
- of a Rapid prop with exactly the same hub appearance and which was undoubtly for Farman or Sommer pusher with a rotary Gnome (the guy found the prop with the crakcase attached)
- and of a partially destroyed Chauvière blade with the same yellow color fabric and which has to be dated between 1910 and 1912 because it was for a Sommer monoplane (tractor prop).

And I am sure the writing is 1,46: not so sure for the 6 but absolutly for the 1. I don't know if other European did the same (at least in the past), but in France we wrote the 1 like this (and put a small cross-bar on the 7 to distinguish it from 1: see the font "Bradley Hand" if you have it in Microsoft Word). A picture from the page http://villemin.gerard.free.fr/aHuma...e/Chiffres.htm which explains how digits writing is teached to child in France:



Regards,
PM
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Old 01-05-2013, 10:02 PM   #18
pmdec
 
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Hi,

I am waiting (from the owner) for larger pictures of a "Rapid" propeller which was for a Farman or a Sommer pusher made between 1910 and 1914. I have only small ones for now, where the 7 holes are not all visible at a time (but they are there!). It seems this prop is very like Dave Burnett's one.

I think we have to consider also a Chauvière blade which have to be made between late 1909 and 1912. It was for a Sommer tractor (not a pusher), but the general aspect of the prop, specially the color, but the shape also, look like the Dave's prop.
I do think the Dave prop is French, but around 1910-1912, there were many prop makers in France (my list goes past a hundred). Someones made props shaped like Chauvières ones, and it is possible we never know who made this one, because too few have survived to compare.

Anyway, this prop is a true piece of history and I am sure it is in very good hands in Canada, away from foolish restorers...

There is a very interesting text which include first aviation hours in Norway here: http://www.europeanairlines.no/wp-co...06-01-2011.pdf
I would not be surprised if the prop would come from one of the aircrafts described (Farman or Sommer) or from a batch of spare parts for them. The script writing seems to be French (or of a "Latin" country), and might be a prototype or a very early prop, before the habit was taken to stamp them. I don't think it is a craft work, because the prop seem too well made and glued (no delamination).

PS: the "Carambar" on the Chauvière pictures is there as a color chart (I have to buy one): think those candies are available everywhere (yet at gold cost in USA!).

Regards,
PM
Attached Images
File Type: jpg Rapid_Wa_cr_text.jpg (37.9 KB, 10 views)
File Type: jpg Rapid_Wa_cr_locations.jpg (38.4 KB, 10 views)
File Type: jpg Rapid_Wa_cr_hub_text.jpg (37.5 KB, 9 views)
File Type: jpg IMGP0166&0168_cr_ac_800px.jpg (87.1 KB, 13 views)
File Type: jpg IMGP0173_cr_ac_600px.jpg (45.1 KB, 7 views)
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Old 01-07-2013, 12:23 AM   #19
pmdec
 
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Hi,

Dave Burnett told me by mail he doubts that the Farmans in the link I gave about first aviation in Norway could be the ones we are looking for, because those "Longhorns" had a rear prop but not a "sanwiched" one and he seems right. So the search has to be continued.

I eventually found a booklet with a drawing of a Gnome which clearly show how the prop could be "sandwiched" (could because the blueprint shows the two possible fittings on the same drawing).
The picture came from this page: http://bleriot11.pagesperso-orange.fr/
The yellow and red colors have been added by me. Not only this sectional view is interesting by showing the two ways the prop could be fitted, but if you look closely the front fitting show 2 bolts (so they must be 6 or 8 ) and the "sandwich" fitting show only one, so they have to be in an uneven number of bolts!
One can see also that the sandwiched prop has a counter-bore at the rear, and could have another one at the front to have a thicker one.
I will made measures on the drawing as soon as I find a precise dimension

Regards,
PM
Attached Images
File Type: jpg GnomeTwoPropsBluePrint_800px.jpg (90.7 KB, 11 views)

Last edited by pmdec; 01-07-2013 at 01:20 AM. Reason: write "8 )" instead of "8)" which show a smiley...
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Old 01-07-2013, 09:26 PM   #20
Dave Burnett
 
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Default Odd 7-bolt Chauvier Prop

Thanks to the work of PM I think that we now know that the 7-bolt configuration was unique to a specific rotary engine pusher application where the propeller was sandwiched ahead of the engine cylinders. In trying to eliminate Germany as a possible source for my prop I find plans that show Albatros Werke GMBH did intend to build a copy of the French Roger Sommer design. Can anyone find evidence that this specific design was produced and if so how many? I know that at the time they quickly modified their aircraft and changed to other configurations and engine types.
http://earlyaviators.com/esommer2.htm
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