sensenich prop, what is it?

[nikejay]

I believe my dad had this on his Smith Mini-Plane until he upgraded the engine... upgrade would have been in the late 70's - or maybe he just changed the prop.
All I can find is an engraving on the blade, RC. No. 1 and TC. No. 691.
Does anyone have a clue on how to interpret what this would fit?
Thanks

[Dave]

Type Certificate 691 (the "TC691" stamped on your propeller) was issued originally to model 43K10107 manufactured by Sensenich under a 1943 military contract, and that model number expired in 1956 but was the same as model 72C 42.

You can look up the various applications for 72 C 42 here, but it is a very commonly used prop on many aircraft using a Continental A65 engine, such as the Piper J3, etc. It should be 72 inches long. I don't know what the "RC" number refers to.

[nikejay]

What is it?

Thank you. I found my dad's log book, and the only plane he owned that had a Continental A65 was the Smith-Mini Plane. I know the maintenance log would have gone with the plane which he sold in 1988/1989. Although the prop matched the engine, it certainly didn't match the plane.
I needed the 'jog' to my memory. My dad has been gone for 15 years. He had stored the prop for years - probably because he hadfinished the build on the plane in the 70's. Thanks again!

[Dave]

Thank you. I found my dad's log book, and the only plane he owned that had a Continental A65 was the Smith-Mini Plane. I know the maintenance log would have gone with the plane which he sold in 1988/1989. Although the prop matched the engine, it certainly didn't match the plane.
I needed the 'jog' to my memory. My dad has been gone for 15 years. He had stored the prop for years - probably because he hadfinished the build on the plane in the 70's. Thanks again!

Well it probably DID go on the miniplane. My understanding is that the Smith Mini Plane is a homebuilt, not a certificated aircraft, in which case the propeller does not have to conform to the Type Certificate standards to which the Sensenich data refers. In other words, it doesn't have to match the certificate data published by Sensenich.