Propellor indification

[Cisse]

Hello,
I'm Cris from Belgium and I wonder if someone can help me with this propeller.
I know it was hanging in a office and then it moved to a attic and from there it moved again to a shed where I rescued it.
The bad thing is that the propeller had been sanded in her previous live and added a dark brown color. So all the letters and figures on the hub are nearly gone, really a shame, also I think but not sure that there was a clock mounted in the hub our something else ? Because there was a piece made in a schape of cirkel on it that was hold together with 4 small nails
Measurements are : length 110 inch, 8 bolt holts with a diameter of the holt 1/2 inch.
The diameter inside the hub on the small site is 5 3/8 inch and the big diameter is 6 inch. Hub thickness is 5 inches. And the bolt holt circle is 7 3/16 inches.

Any help is much appreciated ! Our send me a email at 6cdo@skynet.be for more pictures if you wish, thanks for your time !
Kind regards,
Cris

[pmdec]

Hi,

I have seen props with this kind of big central bore : It could be a prop which was directly mounted on rotative engine crankcase (the one I saw had about 15cm central bore and was for 50HP rotative).

Probably, it is not English, so could you give measurements in centimetres and millimetres ?

"nearly" gone is not "gone", so can you post or send pictures of all 4 sides of the hub and give the blade width ? Have a peculiar look at blades roots. On early props, markings were often there.

I send you a mail for the pictures.

Regards

PM

[Bob Gardner]

Hello Cris,

I have seen a similar looking hub on a prop from a 1912 Bristol Boxkite. It was for a 50hp Gnome in the pusher configuration. I believe that the Gnome engine could be mated to a prop from either side, front or back. But if mounted from the back as in a pusher configuration, the aperture had to be larger to accommodate part of the casing.

Your prop is very different in shape but might be from a Gnome rotary engine in the pusher configuration. However, it does not have the look of an early prop. It is more reminiscent of a late war French prop

But it is also possible that this was a conventional prop which has had the hub centre cut out to accommodate a clock or barometer. If so it has been professionally done by a cabinet-maker. The moulding around the edge of the hole also looks to be later than the prop and also professionally made to a high standard.

The diameter and photos of the remains of the data will tell Pierre-Michel a lot.

With kind regards,

Bob

[pmdec]

Hi,

The prop with the big central bore I saw was also from a pusher (Gnome, probably 50HP).

The diameter of bolt holes circle is very large (7 3/16) and is (imho) an indication the original central bore was also very large even it has been enlarged to fit a clock (I suppose bolt holes are behind the round piece which has been added around the clock). This diameter seems very unusual for "small" thickness, except for propellers monted directly on engine crankcase.

What about the "hole" in the wood near blade root ?

Regards,
PM

[Cisse]

French and American walnut

Just wondering if someone can tell me the difference between French and American walnut ?
And I really want to thank pmdec for all his help and searching. Really appreciated !

[pmdec]

Hi,

Cisse sent me others pictures by mail, so it is easier to have a guess.

Perhaps central bore has been widened, but not all the way through hub. So, it was very large, that is confirmed by bolts circle diameter value. This configuration is known on props directly fitted on rotary engine in pusher configuration (Bob has already said it). That made the prop very old, I think before 1914, as no prop have those characteristics in STAé papers about WW1 props.

The prop seems made of walnut. Anyway, wood has been very carefully chosen (fibers are parallel to laminations length). Those are other clues for pre-war construction.

All markings have disappeared. It is a pity for sure. But it is also another clue for a "primitive" prop : after 1912/1914, markings were made very strongly, but before, there are props with very "light" markings, easy stripped by sandpapering.

All dimensions seems "round" when given in millimetres.

In other hand, prop profile is a "modern" one and perhaps I am wrong all the way... If not, there is not so much props of this kind before 1914, and this one may be a 1910-1912 "Rapid" (but all known have a copper insert) or one of those brand I never saw except in books ("Lioré", "Rationnelle") or on postcards ("Pelliat", "Tellier", ...). Ebora props profile seems also very "modern" (Bob as some infos about them).

So, I hope Cisse will be hapy to have (perhaps !) a very old prop. Unfortunately for him, its value had been considerably lowered by "restoration" ... In this state, it has no value for a museum, except finding a material proof of its origin.

Regards,
PM

[Cisse]

Yes, thank you so much ! So, the prop is used civilian. That rings a bell to me, before 1914 we had a aircraft builder here in Nieuwpoort, the French expression: Nieuport, like the famous airplane used in WW1. He had several hangars and the run a way was on the beach ! Of course that was all changed and destroyed during the first war. Could he build planes with push engines and that the prop survived the war ? I need to ask some people here in Nieuwpoort (Nieuport). I do know he's name and that was Mr. Borgognier.
Our maybe some one else know more about it.