Is this Hélice Eclair?

[Vasek]

Hello,

Several months ago, I got a simple drawing and dimensions for a Hélice Eclair, taken off a Nieuport powered by 110hp LeRhone rotary, the prop dimensions are 2.46m x 2.60m.

Now I decided to make a replica of this propeller. I am just not sure about the exact shape of the blades. Could you help me to get to the right shape to create a drawing from the front view, of the hélice Eclair?

Is any of these the type I am searching for?

Thank you!

[Dbahnson]

It looks pretty close to the Eclair propellers I've seen.

Did you see this one?

[pmdec]

Hi,

I have not enough knowledge to be sure the first pic is of a Nieuport 17 and from WW1 era, but if this is true then the prop has to be an Éclair serial 4 (1.46m / 1.60m diameter and pitch). So, it is a right pic for you.
The second pic is not clear enough to tell anything, but the general look is not the one of an Éclair made propeller.
If the third and fourth pics are from propellers which wanted to be Éclair serial 4 replicas, then their maker has not enough looked at original ones. IMHO, they are totally out of shape and aspect, which are close to English props.

Regards,
PM

[Vasek]

Hello!

Thank you for your comments. Yes, I have seen the one for Caudron G3, but is it the same propeller? Or at least the same shape?

You talk about Hélice Eclair serial 4. Do you own any photo of this propeller from the front view? The Caudron propeller is Serial 1.

Thanks for your help

Vasek

[pmdec]

Hello!

Thank you for your comments. Yes, I have seen the one for Caudron G3, but is it the same propeller? Or at least the same shape?

You talk about Hélice Eclair serial 4. Do you own any photo of this propeller from the front view? The Caudron propeller is Serial 1.

Thanks for your help

Vasek

Hi,

All Éclair propellers have the same "shape".
The serial 4 was only approved for Nieuport XVII and XVIII (fitted with Le Rhône 110 HP) and for Nieuport XXVII (fitted with Le Rhône 110-120 HP).
Most Nieuport were using Levasseur propellers, but Régy 354 are seen in the first years and Chauvière 2228 in 1918 and later.
IMHO, Éclair are rarely seen except on SPAD (some links are suspected between Bloch and Blériot).
I have never seen an Éclair serial 4 made by Éclair, but Éclair serial 4 made under license by de La Granville are not rare. Below is a front view of such a prop: Éclair serial 4 shape and dimensions, but construction process is different, and, sometimes, the tips of the blades are covered with
fabric or parchment, giving the tips the same aspect as the second pic of your first post (on which the white color of the tips and the clear varnish of the rest of the blades are not correct). As for all de La Granville serial 4 I have seen, it has not been used. I suspect these prop were "experimental" and nobody used (or wanted to use) them...

Regards,
PM

[Vasek]

I just found some data about the propeller, and only four were made, according to a document written by Gérard Hartmann.
He confirms the length/pitch 246/260. And thickness of the hub 15cm.

Now I wonder, with such a high pitch, how can the hub be only 15cm thick?

The angle of attack 40cm from the center is already 45°, the blade is 16cm deep, so the leading edge is already 16cm above the desk. I would estimate the hub thickness around 18cm.

Would you find any other photo or a reference of this propeller?

I would like to make an exact replica.

Thank you!

[pmdec]

Hi,

"The angle of attack 40cm from the center is already 45°, the blade is 16cm deep, so the leading edge is already 16cm above the desk. I would estimate the hub thickness around 18cm."
The true hub thickness for Éclair serial is 150 mm. If it was more, it could not be fitted on the hub!
If the blade was 16 cm "deep" with a 45° AoA, the blade width in this place would have to be 16 x 1.414 which is 22.6. The blade has not this width at tis place.
The pic shows a serial 4 SHAM prop made with an Éclair shape for Nieuport XVII fitted with a 110 HP Le Rhône. The chair is an IKEA "Stephan" (see http://www.ikea.com/ca/en/catalog/products/00211088/ !!!).

Regards,
PM

[Bob Gardner]

I am interested in the IKEA Stephan. Is it for sale? I am thinking of opening a forum to gather information on these beautiful items. Would you, M. PM, agree to be our expert on the subject?

With le Respect,

Bob

[Vasek]

Hello,

"If the blade was 16 cm "deep" with a 45° AoA, the blade width in this place would have to be 16 x 1.414 which is 22.6. The blade has not this width at tis place."

Perhaps this is out of possibilities of the forum communication, but I need to clarify some of my calculations. See the attached photo. From the top left to the bottom right you will find out how I calculated the AoA of the blade, particularly at 40cm from the center.
ATTACHED PHOTO

The result is ~16.4cm above the desk. Which is obviously wrong according to the photos you sent me, which show that the blades would actually require thinner hub, than thicker.
What is the 1.1414 in your simple formula?

Thanks for the tip for the chair, unfortunately it doesn't fit the shade of my furniture

Regards,

Vasek

[pmdec]

Hi,

The Stefan IKEA link was to show that the backrest of the chair is 45 cm high above the seat (look at "Product Information" to have the measurements!!!). Then, if you measure the pixel numbers of the backrest and divides it by 3, you will find it is just above the horizontal bar of the backrest, that is 15 cm. On the pics of the serial 4, when the hub is flat on the chair seat, the upper face of the hub is at the same level that the upper side of the horizontal bar ... so the hub is around 15 cm thick. In fact, it is exactly 15 cm thick, but I have no pic with a ruler beside, and no access to the prop itself anymore...

1.414 is the square root of 2, because with an AoA of 45°, the triangle of interest is right-angle and isosceles, so the hypotenuse is 1.414 times one of the sides...
On your drawing wich is up on the right, the blade width is not measured in the right direction: the measurement of the blade width have to be exactly perpendicular to the prop axle, which is the longer straight line which goes from tip to tip AND the middle of the central hole.

True propeller AoA variation rate near the hub is not mathematically helical because it is not possible to made such a prop with wood. And of no interest because this part of the blade doesn't have any tractor effect: it is just there to hold the rest of the blade!

@Bob: I have also red ones, but they are more pricey... Think they used the same screws...

PM

[Bob Gardner]

@Bob: I have also red ones, but they are more pricey... Think they used the same screws...

Merci, mon ami. I hoped to make one or two people smile!

Bob

[Vasek]

Hello,

you helped me to reconstruct the Hélice Eclair 246/260. I am sending a few shots below. I thank you for your help.

It is dark (core) ash.

I accept critics or comments

Front view


Rear view


Side view


Before carving


Varnishing


Inscriptions

[Dave]

Nice job !

[pmdec]

VERY nice job !

With this one, ALL sanded Éclair props without markings become ... suspect

PM