Identification help

[Slingerbeek]

Hello, I live in the Netherland (Amsterdam) and have a old wooden propeller stored in my attic for years. I'd love to learn more about it. The propeller is 2.8 meters long. On the front, it has the text "ETA" stamped. On the side, it says: "185PS BMWIIIa. 6685 Edelzug". Any information or insights about its history or origins would be greatly appreciated.


Does the propeller have historical value? Should I, for example, donate it to a museum? Or is it something I could simply sell to an enthusiast?

Thanks,
Steven

[Mtskull]

That’s a lovely propeller; here’s what I can tell you (there may be others on this forum who can give you more detail):
ETA is the propeller manufacturer, who were based in Berlin.
185 PS refers to the power of the engine, BMW iiia refers to the engine manufacturer and type. (Wikipedia is your friend here; if you search for BMWiiia, on that page is a list of aircraft types that were fitted with that engine).
2,80 and ST 2,20 refer to the diameter and pitch.
6685 May either be a design number or the serial number of the individual propeller. If it is the design number it may be possible to positively identify the aircraft type it was intended for.
EDULZUG denotes the direction of rotation (anti-clockwise according to the German classification, which assumed it to be viewed from in front of the aircraft) and the fact that it is a “puller” rather than a “pusher” propeller. According to convention in most other countries (which state the direction of rotation as viewed from the cockpit), this would be designated “Right Hand Tractor”.
This is definitely of historical interest, especially as it appears original and unrestored and, instead of having bolt holes that pass through the hub, it has four shallow holes, which is characteristic of it being used with a Rupp fastener. This was developed by the German military during WW1 and enabled propellers to be changed quickly. It does not however prove that your propeller had a military application, as the system was used on some civilian aircraft in the 1920’s (Wikipedia has a good photo of a Junkers F.13 with this fastener).
IMPORTANT! Please do not be tempted to “restore” the propeller or do any cleaning other than wiping away any dust. Originality is the key to its value.