12-foot propeller identification

[cpgrant]

I have a propeller that is 12 feet long, tip-to-tip. I can't find any identification on it, other than the numbers "4015" stamped on one blade. There appear to be no markings on the hub, which is 10 inches in diameter and has eight bolt holes.

I live in an agricultural area so it is likely that this propeller most recently came off a ca. 1950s wind machine. I'm pretty sure that it's an airplane prop, though, and not a dedicated wind machine prop.

Any insight you could provide would be appreciated. Thanks!

[Dbahnson]

A ten inch hub and 8 bolt holes suggests that you are correct about it not being a wind machine prop. It could be anything, however. You need to post photos for starters, and we can try to go from there.

[cpgrant]

The propeller is currently located on an upper shelf in a barn with no lighting; I could only get a picture of the hub, sorry.

[Dbahnson]

I'm guessing from the hub appearance that it fits a Liberty engine, and it's a left hand thread so may have been used on a pusher aircraft of some kind.

If the bolt hole circle has a diameter of 8 inches (i.e. 8 inches from the center of one hole across the middle to the center of the opposite hole) and the center hole is 3 1/16" that would match the Liberty engine. Liberty engines were commonly used by the Navy in its flying boat development in the late teens and early twenties, and many of them were sold off as surplus when they became obsolete not long after that.

[cpgrant]

I wonder if there's a reason to use a pusher prop for wind machines, which keep crops from freezing by pulling down warmer air. Can you change the direction of airflow just by mounting the propeller backwards? If these props were commonly used by the Navy I guess that explains why they would end up on wind machines in Southern California.

Is this propeller likely to have any collector value? It's in a barn that I inherited and intend to sell; I'm trying to decide if I should make the effort to move or sell it, or just leave it there for the next owner.

[Dbahnson]

It's almost certainly not from a wind machine and may be worth considerably more than a wind machine prop.

It's definitely worth pulling out and taking some photos of the whole prop, any stampings and decals if present. Feel free to email them to me (you have my email address already) and I can post them.

To answer your question about pusher/tractor, reversing it doesn't do anything to the airflow. The pusher comes from mounting the engine "backwards" from its usual mounting. So a Liberty engine mounted in the front is a tractor and uses a right hand prop. Mounting that same engine on the rear requires a left hand prop and becomes a pusher.

[rjacuzzi]

I was wondering if you ever identified your propeller? If you still have it could you post some pictures of the whole propeller? Thanks