ID Please?

[ahranis]

Followed your steps.
I did the best I could.

A1(0.9 m): 16,7 degrees
A2(1,0 m): 15,9 degrees
A3(1,2 m): 14,4 degrees

I am not sure what tg(x) stands for.

Is it tan(x)?

Anyway, hope this helps!

[ahranis]

A1: 186*3,14*1,53=894
A2: 200*3,14*0,19=119,38
A3: 240* 3,14*(-3,72)=-2.804,81

Doesn't seem good to me
I am sending the prop there for examination...

[ahranis]

Never sent this

[ahranis]

Doublechecked it.
Flat side of the blades again.
Same readings.

On the other side of the blades, the angles tend to be more close to the diagram you attached but I can not take safe readings because of the curves.

[ahranis]

I think I found my mistake.
The angles I measured are between the flat side of the blades and the flat side of the hub.
But you asked for the degrees between the flat side of the blades and the rotation plane. So...

Is it ,

A1: 90-16,7=73,3
A2: 90-15,9=74,1
A3: 90-14,4=75,6
?

seems worse now

[pmdec]

Hi,

Yes, "tg" is tangent, but to compute the tangent, Excel and some calculators need to convert the angle in radians first... So the pitch is (Excel formula):
P = 2 * PI() * r * TAN(RADIANS(angle))
where "r" is the radius and "angle" the angle in degrees.

By the way, I have some interesting answers about Salmson aircraft in the French forum, specially somedy who wrote that the Salmson-Moineau SM1 AC2 engine was adverted for 260 HP in 1932 in a Salmson brochure. Yes, it is late, but it would explain where a right handed propeller could be used with a 260 HP Salmson engine. The problem is I don't know what is the gear ratio in this very strange mechanics of the SM1 aircraft!

I will come back this evening or tomorrow...

Regards,
PM

[Bob Gardner]

Wow!

Who would have thought when Dave Bahnson started this forum that it would produce such erudite correspondence.

With reverence,

Bob

[pmdec]

Hi,

Bad news: I have found two props used on the Salmson-Moineau SM1 but the data "tell" that the prop rotational speed was less than the engine.
Salmson prop serial 18 and Régy prop serial 331 had identical caracteristics with a 295 cm length, 265 cm pitch and a 255 mm blade width. The larger diameter, length and pitch vs the props for Salmson 9Z are from a rotation speed largely lower.
The ahranis prop, with a length of 279 cm and a pitch less than 2 meters, cannot be used for this plane, and it is the only plane I have seen (which is far from a proof that there is not one!) with a right handed prop.

Anybody an other idea?

Perhaps interesting to note : there was a Régy serial 372, the first*** Régy for Salmson 2A2 with a Canton-Unné Z9 which was 280 cm length, had a 210 cm pitch and a 233 mm blade width. This is quite the same that ahranis prop. But all pics show a left handed prop on this aicraft... Is it possible to make the engine turning the other way for whatever raison?

*** Replaced later by the 804.

Regards,
PM

[Dbahnson]

Is it possible to make the engine turning the other way for whatever raison?


Regards,
PM

I've seen opposite thread props for a Bristol airplane, but it was a twin engine aircraft so the counter-rotating propellers had a certain advantage in neutralizing the adverse yaw forces that were inherent in any propeller. I suspect it's not overly complicated to reverse the engine rotation from an engineering standpoint, but why would that be done for a single engine aircraft? I certainly don't have an explanation.

[ahranis]

What about these?

It was a training plane manufactured in Greece using a Salmson engine.

https://www.haf.gr/en/history/histor...lidwn-swallow/
https://en.m.wikipedia.org/wiki/KEA_Chelidon

Maybe other planes were modified after the end of the war to serve civilian causes.

I know I often say things that you already know.
Just trying...

or these two

https://www.haf.gr/en/history/histor...ulnier-ms-147/

https://www.haf.gr/en/history/histor...t/hanriot-41h/
... and I am Stopping now

[pmdec]

Hi ahranis,

The four links are for planes with Salmson 120 or 130 HP. It doesn't explain the marking CU 260. Yes, it is possible that the markings are erroneus: it would not be the fist time it happens. But if we suppose that, what have to be rejected?
Keep in mind that the prop:
- has been made in France (by Mormesse under Régy license) and later repaired or modified also in France (by Chauvière) and each time the work was approved by military controller.
- Its making has to have happened in 1918 or 1919: after this time, no more licensees made prop for the army.
- And yes, it could have been used later with "not approved" fitting, but we have to find an aircraft suitable for its first usage and also after repaired. And it there we have a problem: the prop has the same caracteristics that those for Salmson fitted with 260 HP engine... but it is right handed vs left for this aircraft. Perhaps, as supposed by Dave, it was possible to have the Z9 rotating "other way". But why? Don't forget there was "administrativ work" to make such a propeller constructed and approved...

Perhaps I forgot something in plain view that suggest an answer? It would not be the first time...

Regards,
PM

EDIT : replaced cabalistic signs by é and è.

[ahranis]

Understood!

I will keep a radio silence and try to make a local research. I am really glad I had this little educative contact with your specialties and I hope I wasn't such a bother.

I wish I come back with usefull informations.

with appreciation ,
Nick

[pmdec]

.../... and I hope I wasn't such a bother. Nick

Hi,

Not a bother at all: exactly the contrary! "Strange" props are the most interesting!

Just one more pic to show what I suppose was the pigskin "shielding" of your prop, here on a Chauvière 2463 for a Dorand.
This shielding (blindage in French) was made by SHAM and patented by them.
From prop number (73664), it was probably made between 1919 and 1921. BTW, nothing can be told from the prop number of yours because Mormesse production is not known, at least by me.

As you can see, SHAM shielded [right word?] prop had a small brass plate, nailed to the prop. I suspect many came loose...

Regards,
PM

EDIT: replaced "licensed" by "patented" and added the patent.