Helice Normale

[pmdec]

Just a quick pass through here to see where is now this very interesting thread...

@Dave: "So how far "up" does a 6 degree angle go in a distance of about 660 cms?" The answer is 660 x tangent*** (6°), that is 660 x 0.105 = 69.3 cm. This number is a geometrical pitch. Numbers given by Ratmanoff are "aerodynamical" pitch: that is the true displacement of the aircraft for one turn of the engine, and he rightly calls that "advance by turn". He can't give a pitch, because his propellers have not an identical geometrical pitch along the blade.

Note that on your picture (Plan of a blade, fig 219), the geometrical pitch increases regularly along the blade because there is a constant 3° angle added to the distance proportional angle indicated by the angles written for each section.
But it is NOT the case for Ratmanoff props. The geometrical pitch increases from hub to tip, but the increase is not regular. On a figure like this for a Ratmanoff, the "added angle of 3°" is different for each section.

Note also there have to be a mistake or a miswriting (or I misread the numbers) for the "F" section: the angle can't be 25°25', but higher, around 25°55'.

*** You can use the Windows calculator (chose the "scientific display") to compute all this. Don't forget to tick the "degrees" option (by default, it is the "Radians" option which is chosen: 360°=2 x 3.14 radians). And you have also to convert sexagecimal degrees (° ' ") in decimal degrees (add to degrees number the minutes divided by 60 and seconds divided by 3600).

@Pete: Without being pedantic, I think you can read this to see how was the "thinking" about propellers in first years: http://www.archive.org/details/treat...rscr00parkuoft . It is from 1920, so already far from the 1907-1914 years, but I don't know anything in English from the first propeller making years. You will see this is not about the story of a guy who buy some boards at Home Depot... Drzewiecki writings from 1909 are as sophisticated

Not so quick pass!

Regards,
And, one more time, sorry for my rude English,
PM

[drrivah]

Helice

The Park treatise has been the basis for my designs and speculations for a few years, along with Durand's 1917 NACA reports (No. 3) and other original papers. I believe the Ratmanoff most resembles Durant's "A1S1F1" model, the source of my proposed Ratmanoff model data and calculations above.

Park's book is a nice handbook, but it doesn't really delve into why a designer might increase, then decrease the face pitch (angle of incidence nonlinearly applied) at certain radii. That's what I get when I model the Ratmanoff.

The prop disc from ~50-90% radius seems to show a negative angle of incidence if P=0760. Could be measurement uncertainty or perhaps an intentional design feature like the very interesting structure of the Garuda props.

There are a few series of propeller airfoils designed in the period between 1908-1917 from NPL, Eiffel, Goettingen and the RAF. I believe coordinates on all are publicly accessible through Univ. Illinois. If one can identify the airfoil dimensions and thereby, the airfoil series, of an unidentified prop, you may be able to more precisely date a propeller.

For example, if Eiffel's series wasn't published before 1910 and his sections are used, that might date the prop to 1910 or after, yes?

And BTW, is there evidence that Eiffel, Ratmanoff and Drzewiecki were all acquainted with each other, as is common among academic engineers and scientists working in the same or nearby cities?

If you return to the Wright brother's original correspondence & letters, yes, I do believe they would have used Home Depot, had it existed in 1900-1903.
Specifically look at their sourcing for hinges, for example.

Dave's end-on photo of the Ratmanoff holds a surprise (for me, at any rate): I do not believe the tip is warped. Specifically, there are airfoils that are shaped somewhat sigmoidally known as "reflexed curvature" (see Judge [Properties of Airfoils and Aerodynamic Bodies, Selwyn 1917] Figure 60, below). Interestingly enough, Eiffel showed that such a profile creates lift above 6 degrees incidence, exactly what Dave measured. Could be coincidence.

Why did Drzewiecki specify such a reflexed curvature for his prop tip on the Ratmanoff? (Answer is not in Park's book, BTW).Yes, I agree there is some sophistication there about fluid dynamic properties and prop tips.

A few other structural questions:
-does the hub bore of the Ratmanoff have slightly larger bore on both faces
than the central lumen of the bore? (compression space)

-the Ratmanoff model I'm looking at predicts lamination joints on the back (engine side) at about radii 260mm, 390mm and 611mm, and then no face laminations from 611mm out to the tip. Yes?

-Finally, the usual wood specified is ash, walnut or mahogany, but the Ratmanoff looks lighter, maybe heart pine, maple or poplar. The distal tips seem to have been covered with doped linen beyond the decal, preventing the outer blades from "sunburning" which happens to cut wood exposed to sunlight.

Provide an email and I would be happy to send the model parameters for critique.

Best,

-@pete

[pmdec]

Hi,

Just true very quick words...

.../...

1 There are a few series of propeller airfoils designed in the period between 1908-1917 from NPL, Eiffel, Goettingen and the RAF. I believe coordinates on all are publicly accessible through Univ. Illinois. If one can identify the airfoil dimensions and thereby, the airfoil series, of an unidentified prop, you may be able to more precisely date a propeller.

For example, if Eiffel's series wasn't published before 1910 and his sections are used, that might date the prop to 1910 or after, yes?

2 Dave's end-on photo of the Ratmanoff holds a surprise (for me, at any rate): I do not believe the tip is warped. Specifically, there are airfoils that are shaped somewhat sigmoidally known as "reflexed curvature" (see Judge [Properties of Airfoils and Aerodynamic Bodies, Selwyn 1917] Figure 60, below). Interestingly enough, Eiffel showed that such a profile creates lift above 6 degrees incidence, eaxctly what Dave measured. Could be coincidence.

3 -the Ratmanoff model I'm looking at predicts lamination joints on the back (engine side) at about radii 260mm, 390mm and 611mm, and then no face laminations from 611mm out to the tip. Yes?

4 -Finally, the usual wood specified is ash, walnut or mahogany, but the Ratmanoff looks lighter, maybe heart pine, maple or poplar. The distal tips seem to have been covered with doped linen beyond the decal, preventing the outer blades from "sunburning" which happens to cut wood exposed to sunlight.
.../...

1 I think there were too many props designed between 1907 and 1914 (while WW1, it is another story) to use these data: more than 50 brands, each with its own shape.

2 Some first Ratmanoff designs do show sections with a "sigmoid" profile.

3 What kind of Ratmanoff are you looking at? Before 1914, all are constructed with all laminations except one (eventually two) going up to the tip on intrado side (which can be not the side facing the pilot, because many props among the first ones are pusher).

4 From memory, all constructed with walnut or mahogany. I will check with my books at the end of the week.

Regards,
PM

[Dave]

Between walnut, mahogany and pine I would be almost certain that mine is walnut. It's not dark walnut, but is very similar in color and grain to this British Avro prop. I think an amber colored shellac makes it look "different".

[drrivah]

Walnut Hue

Certainly, (American) walnut comes in many hues. I've seen some from the farm here that is almost butternut yellow whereas heartwood can be almost dark chocolate for large timber. I had heard some very early props were heart pine (Pinus palustris).

If I can manage a volumetric estimate given your prop dimensions, I should be able to calculate a weight and weight range. Since the density of various wood species (and their % water content vs season), is well known, it may be possible to simply weigh the prop to rule out some wood types.

Yes: walnut is probably most likely.

I wonder whether there are consistent hue differences between American and European/French walnut.

-@pete

[drrivah]

Anzani Hubshaft

Here are a few of Anzani engines from a colleague photographed recently at Old Warden. The black one is from an Anzani 6 cylinder. The silver, from an Anzani Militaire (3-cylinder fan type). The latter is a modification of the Channel Bleriot Anzani. No photos of the actual Channel Anzani crank/Bleriot.

A question: these cranks look tapered. Is the hub bore on the Ratmanoff Helice Normale straight or tapered with increasing diameter anterior to posterior? If no taper, bore on both faces of hub will be identical diameter.

If tapered, the difference in diameters at 94mm depth should give the exact taper angle. The crank from the 6-cylinder looks to have an anterior-to posterior curve.





-@pete

[Dave]

I don't know if I've ever seen a taper on the prop itself, and the Normale prop and Ebora props both have cylindrical center bores. The tapered crankshaft end fits into the machined metal hub which has a cylindrical outside and a conical inside bore.

Was that your question????

[drrivah]

Anzani: from prop to engine IDs

The question was:
1) how to extrapolate from the prop hub detail, bore diameter, bolt pattern and spacing, back to which model Anzani engine it matches. Is it possible?

2) Are all Anzani hubs the same dimension?

BTW, thanks for hub vs crankshaft comment.

Looks like the more powerful six-cylinder 45-60/70 hp Anazani engines (late, maybe 1926-192 did, in fact, have 8-bolt hubs. The 22-35 hp appears to have 6 x 10mm @ 57.5mm radius hub.

Here are three Anzani crankcases. The one on the left is apparently a Channel 22 hp W-type (57o between cylinders) with valves behind the cylinders. Note: no "B te" marking at about 8 o'clock position on ther face.

Center is the Old Warden Anzani Military Type on display (not mounted on an airframe) at about 35 hp. The valves are on top of the cylinders and visible from front. Here, "B te" appears.

On the right is a later Y-Anzani of 35 hp with the "Brevete" spelled out ('Patented', Fr.).

Curious which prop markings identify the engine it was designed for.




(from:L Ghosts; middle N. Feltwell; right: Janes 191

-@pete

[Dave]

The question was:
1) how to extrapolate from the prop hub detail, bore diameter, bolt pattern and spacing, back to which model Anzani engine it matches. Is it possible?

2) Are all Anzani hubs the same dimension?

BTW, thanks for hub vs crankshaft comment.

Looks like the more powerful six-cylinder 45-60/70 hp Anazani engines (late, maybe 1926-192 did, in fact, have 8-bolt hubs. The 22-35 hp appears to have 6 x 10mm @ 57.5mm radius hub.

Here are three Anzani crankcases. The one on the left is apparently a Channel 22 hp W-type (57o between cylinders) with valves behind the cylinders. Note: no "B te" marking at about 8 o'clock position on ther face.

Center is the Old Warden Anzani Military Type on display (not mounted on an airframe) at about 35 hp. The valves are on top of the cylinders and visible from front. Here, "B te" appears.

On the right is a later Y-Anzani of 35 hp with the "Brevete" spelled out ('Patented', Fr.).

Curious which prop markings identify the engine it was designed for.




(from:L Ghosts; middle N. Feltwell; right: Janes 191

-@pete

I also own this Chauviere propeller for a 125 HP Anzani engine, which clearly used an 8 bolt hole hub with entirely different dimensions than the smaller engine.

I find on many engines the hub is the same for various horsepower versions of the same engine. I don't know about Anzani engines, but the hub on the Ebora prop (which is stamped 28 hp Anzani) is identical to the hub on the Normale prop.

[drrivah]

Ratmanoff serial B

"Ratmanoff Normale serial B is present in two documents I have copies of:

***- a price list dated October 1910, were B props are for Blériot XI fitted with a 3 cylinders Anzani 25HP, "advance for one turn" 0m76, speed 60km/h (so 1315rpm without slipping). Price 350F. ***

- a price list dated 1st January 1914, were B props are for Anzani 30HP at 1250rpm, with a length of 210mm and a speed of 70km/h. The prop has a nickname: "moineau" (sparrow). All props listed in this document have a bird nickname. Price 250F (lower than 1910 price)."

A colleague has brought my attention to a table listing Anzani engine types, among which is an Anzani type 6B (1910), 1300 rpm, 40 hp, 6 cylinders. Is it possible that the "serial B" above matches this engine to the Ratmanoff Helice Normale?

-@pete

[drrivah]

Helice weight and metrology

More speculation:

The density of wood from each species varies, but they generally have a range and engineering specs takes into consideration the variation. Later (191, there were specifications about wood density allowed in prop manufacture, usually a minimum density. In addition, as with modern aircraft wood grading, the allowable grain rise was also specified at least by 1918.

If the specs are accurate, a volume can be estimated by rough or more exact methods.

Rough guess on the Ratmanoff Helice Normale, given a lot of assumptions, is:

English walnut: 8.9 lb (grain <1/12)
Mahogany (H) 7.6 lb
Ash 9.3-10.1 lb (grain <1/10)
Pine (y) 6.9 lb

My guess on the estimates is +/-15-20% uncertainty.

While these guesses may be coufounded by overlap between species, a walnut prop shaped like the Ratmanoff should be about 8.9 lb.

Not sure how wood (walnut) changes density with time as this would be ~ 100 years since the prop was manufactured. My guess is that as wood dries over time, it becomes lighter (in weight, losing mass). If shellac/varnish is intact, this would be minimized.

Pure speculation, of course.

-@pete

[Dave]

A colleague has brought my attention to a table listing Anzani engine types, among which is an Anzani type 6B (1910), 1300 rpm, 40 hp, 6 cylinders. Is it possible that the "serial B" above matches this engine to the Ratmanoff Helice Normale?

-@pete

I have no idea.

Incidentally, I came across this photo of an early Anzani engine used on a Caudron in the mid teens, clearly showing a 6 hole hub.

[pmdec]

Hi,

Returned (snowy!) home and to the books. Circa 1911, Ratmanoff props are all made with English walnut (that is French walnut for French ). Scientific name is Junglans regia, which is different from Junglans nigra, the American wallnut. Ratmanoff is said to use only timber from Auvergne (south-central part of France), where walnut grow slowly and regularly. This "sub-specie" is light colored (http://www.thewoodexplorer.com/maind...ts/we671_1.jpg)
English walnut wood density may vary from 0.45 to 0.65 (from different publications), so measuring density is not a method to determine the wood specie. A good cabinetmaker has to know the precise wood specie.

@Pete
About Anzani engines. There is a drawing of the "25HP" 3 cylinders (fan type) in Flight, October 30th, 1909 page 691. There are many models, even before 1914: for example, there was a "40-50HP" 5 cylinders at 1910 Paris Show (see Flight, October 29th 1910, page 886), a "60HP" 6 cylinders on a Blériot which flew on July, 11th, 1911 (see Flight, July 22nd 1911, page 642) and a "100HP" 14 cylinders appeared at 1911 Paris Show (see Flight, December 23th, page 1114).

It is not possible to determine a specific engine from metallic hub dimensions, even if these dimensions are a guess basis to engine power. All known metallic hubs from this period have a tapered interior hole with a cylindrical outside.

From the documents I have, the Ratmanoff Normal serial B is not suitable for other engines than Anzani "25 to 30HP" 3 cylinders. For the 1910 5 cylinders, there are serial Q and L1 and at the end of 1913, there are 23 different serials (from 2m000 to 2m800) for aircrafts fitted with one of the Anzani engines.

@Dave
Your picture is of the Caudron "Fauvette" owned by Guillaux. The engine is an Anzani 3 cylinders Y type, and the propeller is a Ratmanoff, perhaps a serial YA (diameter 2m10, with an advance by turn which give a speed of 120km/h). This picture is from 1912, probably between February and August (no later, as one postcard with this very picture is dated August 12th, 1912, and probably not earlier, as first pictures of Guillaux published by the postcards editor Briant are from February, same year). This very aircraft is recognizable with its small mascot, a little doll visible behind the upper cylinder.

I have to admit many of the props of this period have a six holes hub, but the picture with eight holes from l'Aérophile I posted is, for me, the more accurate about Blériot Trans-Channel flight, until I can look at a picture taken just after the landing.

Regards,
PM

[drrivah]

Anzani props

PM: Virginia like Spring this week. Narcissus near bloom, and snowdrops in bloom. We are "waiting for the other shoe to drop".

Very interested in further technical data comparing French, English and American walnut, eg., density, modulus of elasticity etc., and how these change with the age of sealed (varnished) vs raw stock wood/timber.

Thanks for this informative response with great technical detail.

-@pete

PS PM an email address: I'd like comments on my Ratmanoff model.

[D.Hicklin]

origin of thread

And to think, this wonderful thread all started by the member " rolex " with a picture of a block of wood that had the logo on it that says, " Helice Normale ". Truly impressive how it all links together.

Sincerely,
Dennis Hicklin
Seattle Washington.