Identification of possible prop wood?

[MarkMcM]

Gentlemen,

I have a section of what I believe may be German WWI propeller wood. I understand that identification of such a thing is a challenge, especially when only a segment is available for study. The wood in question is of laminate construction, and I would be happy to post photos along with some measurements of the relevant thicknesses. In the meantime, I was wondering if it would be possible to request some dimensions taken from known examples? It might help narrow the focus if I could ascertain the thicknesses of the laminate wood composites used in the construction of the following 3 propellers:

1: Heine Propeller, 100 PS, ARGUS D 290 ST 190

2: Axial Propeller, Fokker DVII

3: Anker Propeller, 200 HP Mercedes

Any help would be greatly appreciated! Thanks!

[Dbahnson]

The only one of those that I still own is the Anker 200 HP. Are you just looking for the thickness of the layers?

[MarkMcM]

The only one of those that I still own is the Anker 200 HP. Are you just looking for the thickness of the layers?

Yes, that’s essentially what I’m hoping will be the key. Here’s the object in question. The thickness of the lighter colored wood is approx .750, while the thickness of the darker wood is approx .425.


http://www.woodenpropeller.com/forum...EAAAICRAEAOw==

[Dbahnson]

On the Anker propeller, the lighter wood is slightly thicker than 3/4" and the darker wood is very close to 3/4". Looking at thicknesses in the DR1 propeller and the Rahjten propeller, there is a lot a variation in wood thicknesses, with some showing thinner light colored wood and thicker dark colored wood. Some of that may be due to differential shrinkage among wood species.

I doubt that there is sufficient correlation of plank thicknesses to help much with identification, although it is fair to say that German manufacturers were more likely to use mixed woods.

[MarkMcM]

That’s interesting... have you observed any distal tapering or hub-to-tip thickness variation of laminate sections prop construction?

[Dbahnson]

That’s interesting... have you observed any distal tapering or hub-to-tip thickness variation of laminate sections prop construction?

I don't believe I have, but I haven't looked for it either. When you look at the typical lamination process, however, I don't see what would be gained by tapering the planks before glue-up, especially in a two-blade construct. I don't recall the joinery for three- and four- bladed construction.

[Garuda]

British propeller thicknesses of each lamination were specified on the drawing. German propellers had laminations which varied enormously in thickness and sometimes in terms of species. Provided the overall shape was correct the Germans made their propellers from whatever stock they were able to obtain. I have a Garuda propeller which has a lamination of European Ash which is 11mm thick and the front lamination is 35mm thick on one side and 37mm thick on the other side. It appears to be Walnut. I am not aware of any propeller which has laminations which are tapered towards the tip. The Garuda propeller I have has laminations which taper from one side to the other. This has almost certainly not been done deliberately but is yet another example of the fact that German manufacturers were not too concerned about the individual lamination thicknesses, only the resulting shape.