Helice Mercure Paris

[MartyF]

Can you help me identifying this propellor?
It has a round decal on each of the two blades showing the God 'Mercury' in Gold on a red background surrounded by a blue border with the words 'HELICE MERCURE PARIS'.
The blade is 90" long and made of laminated wood with a central boss surrounded by 8 bolt holes.
The only other marking looks like 'AP16' and '182' stamped near the boss.
Anybody know its origins?

[pmdec]

Hi,

Hélice Mercure is a relatively well known propeller maker. He was in activity between 1912 and 1920. Yours seems to be a 6-bolts hub modified in 8-bolts hub.
For more information you have to :
- give precise measurement of prop overall length, blade width, hub thickness (not width), size of the central hole and size of the circle who pass by the center of bolt holes,
- post clear and large pictures of 4 sides of the hub (two rounded and two flat sides). As pictures size is limited on the forum and the faint markings have to be viewed on largest size available, you can send me pictures by mail at :


Regards,
PM

[MartyF]

Sending e-mail

Hi PM
Many thanks for your response.
As requested, I will e-mail you with more photos as well as a document showing all the sizes.
MartyF

[pmdec]

Hi,

I received clear and large pictures which confirm I am in a very intriguing situation with this one:
- decals are the first ones used on Mercure propellers between 1912 and 1921, so probably before 1918. They seems original BUT they are placed the wrong way on the blades (turned 90°).
- markings look like Ratmanoff ones (A° 16 182, which is serial A° number 16 and prop number 182) and known Mercure have their markings on the side of the hub,
- shape also very closed of Ratmanoff, and known Mercure with blades aligned and with a width enlargment at about 4/5 of the blade.

So, I am waiting for exactly face and front pictures for a better view of the shape.

Anyway, a very interesting prop, probably from the 1913-1915 era.

Regards,
PM

[pmdec]

Hi,

Ratmanoff vs Mercure. A 1912/1913 Ratmanoff (extrados/intrados) above a 1917 Mercure (extrados/intrados). Both for ~ 100HP engines. Late 10's Ratmanoff had the same shape, but the shape of pre-WW1 Mercure is not known (to my knowledge).

Regards,
PM

[MartyF]

Not Ratmanoff

The ends of my propeller are certainly not 'squared', so I would say it is not a Ratmanoff.
I will get some decent photos as soon as I can to show you a full view front and back. (Rather busy at the moment).
Regards
Colin

[MartyF]

Final head-on shots

PM
Here is the best I can do to show the front and back head-on.
You can see that they have suffered a little damage at the tips, but were never square ended as in the Ratmanofs.
One final measurement was the logos which are 60m diameter.
Anybody else know the year of manufacture exactly?
MartyF

PS
After a little research, I am told that this prop was originally in a school museum in central England which of course gives no clue as to its origin or why a French propeller ended up there!

[pmdec]

Hi,

Not strictly squared but close, anyway. And geometry of blades (leading edges alignment AND how the extrados tips are "rounded") are the same as Ratmanoffs.
Add the serial numbering pattern, and you have an early Normale propeller: even the fonts are the same (look at the 1, the 2 and the 6).

For me, it is a very early 6 bolts Ratmanoff which have been
- lightly sanded (markings are not gone but have became "light"),
- modified to 8 bolts,
- with "tappering" of the central hole to fit a more recent metallic hub.

Perhaps theese modifications have been made in Mercure workshop? In those times (before WW1) there was no airworthy inspection for civil use.

In each of the pictures below there is a Ratmanoff (a serial KU from our collection) and your "Mercure"? Did you see big differences? I know this is not the scientific way (no visible difference >>> same thing is not a pertinent statement, because only differences can be proved) but in the relative small word of pre WW1 propellers, I do think it the beginning of a proof

Infortunately, the length of Ratmanoff serial Aº is not known. Serial A 3 et A 5 were 2,40 meters, serial A 6 and A 8 were 2,50 meters [all those digit in exposant place, but I don't know how to make this in forum text]. So, 2,30 meters (as yours) for serial Aº could be rational.

Regards,
PM

French propellers of WW1 and pre-WW1 era are found everywhere. Not a clue.

[MartyF]

Conclusion

Hi PM
Many thanks for your comparisons. I guess we can make no further progress with identification.
There are just a couple of things which are bugging me:
1. Which came first the 8 or the 6 hole hub modification?
2. I notice elsewhere in the forum (under Abbreviations) that the prefix AP (mine is AP16) refers to Aeromarine Plane & Motor Co in 1918. Does this refer to the U.S.A. only?
3. You refer to your collection (museum?) in France. Where exactly are you.
(I happen to be driving through France next week, though I am going to the South East and I think you are in the South West.)
Colin

[Dave]

"AP" is almost certainly applicable to some US propellers only, and even there AP may appear for a different reason and not refer to that company.

[MartyF]

Just re-read previous post and realise my question 1 is already answered!
Also, if this was formally a Ratmanoff, who put Mercure decals on?

[Dave]

It doesn't look like there are any Ratmanoff-like drawing numbers in the markings, so I suspect it's not "originally" a Ratmanoff propeller, even though the designs are similar.

[pmdec]

Hi,

Hi PM
Many thanks for your comparisons. I guess we can make no further progress with identification.
There are just a couple of things which are bugging me:
1. Which came first the 8 or the 6 hole hub modification?
2. I notice elsewhere in the forum (under Abbreviations) that the prefix AP (mine is AP16) refers to Aeromarine Plane & Motor Co in 1918. Does this refer to the U.S.A. only?
3. You refer to your collection (museum?) in France. Where exactly are you.
(I happen to be driving through France next week, though I am going to the South East and I think you are in the South West.)
Colin

1: as you just written, I think it is a 6 holes modified in 8 holes, with 4 dowels in the no more used holes (see last pic of my post)
2: I think the vertical bar of your P is a scratch. It is not oriented correctly to make a P. For me it is Aº (A exponent 0), perhaps A^5 (A exponent 5), but A^5 Ratmanoff was 2,40 meters long and yours is 2,29 as you said me in a mail.
3: Our small museum is in Figeac (Lot). A (relative) long way from south east of France. You have a Google map there: https://maps.google.fr/maps/ms?msa=0...5&source=embed (sorry for the length of the address!).
If you are going there, send me a mail before.

@Dave: Yes, pre-war Ratmanoff serials have this drawing number pattern. A3, A3bis, A5, A6, A8, J1, J3, K5, K5bis, K6, K7, K8, L1, L4, U2, X1, X2 and X3, all with capiltal letter and digit in exponent place. And the habit about Ratmanoff serial is a number just after this X² and another number after a space. To my knowledge, they are the only props with exponent digit after a capital letter before WW1.

If this prop is a A^5, it could have been modified in Mercure shop to fit another aircraft: diameter reduced, 8 holes and tapered extremity of the central hole to fit a latter metallic prop hub. Ratmanoff A^5 was for Antoinette with a 50HP engine and made to have a speed of 92 km/h.

The pic is cropped from a pic sent by MartyF and with higher contrast. For me, the sign after A is not a P. It could be a 0 or a 5. Both are plausible. Look at the other digits on other pics: the boucle, when present, "thightens" at the extremity. All known pre-war Ratmanoff props have this kind of "font".

Regards,
PM

[MartyF]

Pointed tips?

After further discussion with my seller, he informs me that he was told that the tips of this propeller were originally pointed. In this form, the aircraft would not fly properly and so the ends were 'squared off' to make it fly.
I cannot verify this information but it makes things even more complicated.

I would be interested if anyone has a picture of what kind of aircraft this would have been fitted to.

[Dave]

That makes sense, as 90" is a little shorter than most of the "typical" WW1 era propellers. You can tell somewhat by looking at the tip end on. It will be thick in the middle and thinner at the back and front.

"Squaring off" of the ends usually was the result of damage. It's possible that it was retrofitted to another engine and was simply too long, or it might in fact have had different performance with the tips removed, but generally if that was an aerodynamic problem they simply would have installed a different propeller.

Finding a picture is futile unless you can identify it further.