1920"s; Have prop ID, need manufacturer

[TFey]

This is a 10 foot 8 inch propeller marked for use on a supercharged V-12 Liberty engine and may have been used on the Martin Bomber circa 1922. The "A.S. designates "Air Service". The black-and-white photo of the logo on another prop is from a document that positively identifies this as a propeller from the Martin Bomber, however no logo was found on the propeller in the color pictures. Does anyone have information or ideas on who may have manufactured this propeller? Stone? Thanks.

Tom

[Dbahnson]

I think the "M.B." on the stampings certainly suggests the Martin Bomber, but I don't understand how the black and white photo "positively identifies" it as such.

Also the black fill in the lettering is a little unusual, and makes me wonder if it has been refinished at some point, which also might explain the absence of decals identifying the manufacturer.

[TFey]

The Part No on the color prop has been cross-referenced to an Air Service document that states the prop is designed for a supercharged Liberty. Which of course it says on the hub.

The Smithsonian has provided documents (attached) for a similar propeller (same Part No) which is documented to have been used on the Martin Bomber. So the Part Numbers and "M.B.Supercharger" information stamped on the hubs line up between the color prop and the photocopied prop with the positive ID.

What I'm hoping is that a clue to the manufacturer of one (or both) props may be gained by identifying the logo on the prop in the Smithsonian photocopy.

Thanks.

[TFey]

Document from the Smithsonian.

[Dbahnson]

I've seen the decal before but can't recall whose is was. Maybe US Propellers, Inc.? I'll see if I have an old photo of one somewhere.