Unknown rectangular prop

[JMPM]

Hello!

A far acquaintance (friend of the father of a friend of mine) has this propellor on his wall. It is appr. 190 meter (75 inch) in length and the hub is about 25 cm (10 inch) wide. I guess it is about 15 cm/6 inch deep. The large shafthole is surrounded by 8 small boltholes. I made a quick picture with my phone. It looks like it's fabricated out of one piece of wood. The edges are covered in a black substance (paint?) and finished with metal sheeting. The owner has no clue of what it is and how he got it... As the prop was hanging rather high and I was in a hurry, I couldn't see any details/data.



Any ideas?
Original or fake? It looked quite authentic.
What era, manufacturer and/or country?
Airplane, generator, UFO or even a zeppelin?

I'm just very curious and wouldn't keep this 'search and determine' operation just for myself.

Thanks.

JMPM

[Dave]

It certainly looks more like an airboat prop, or similar type of use.

[Bob Gardner]

Jochem,

I believe it is a German brake prop from WW1, an airbrake prop, used for testing engines. Air brakes of varying sizes were fitted to those dark plates at the end. They sat at right angles to the prop, directly against the airflow. The prop was then fitted to a newly built engine and run on test. If it could reach the required test revs, it was producing the correct bhp and was accepted into service. The prop is called a Bremsschrauben in German.

If I am correct (I have only ever seen one), it is a valuable historical item which should be put in a museum at some stage.

Please go back and photograph it properly with close ups of the data.

With regards,

Bob

[JMPM]

Thanks for the replies, Dave and Bob.

My first guess was an airboatprop too, but it looked to heavy, sturdy and weird...

I never heard of a bremsschrauben before, but it sounds exciting. I can ask the owner if there are certain markings, data and/or scars (for mounting the airbrakes) on the prop. If I get any reply or pictures, I will post them on this forum. I don't think I will be able to see it myself soon. Bob, do you have a picture or further data of the bremsschrauben you mentioned?

Thanks again and I will inform you if there's any further progress.

Regards,

Jochem