Help ID engine/aircraft Sensenich DES 690 installed on...

[FoolThrottle]

I was recently given a Sensenich 6' prop from an airport restaurant that was closing vice a new facility. I know from the serial number it was made between 1932 and 1942. I was wondering if there was any info or leads on what engine or aircraft it may have been installed on.

Stamped info:

- DES 690
- Ser 6421
- HP 40
- RPM 2575

Thanks!

[Dave]

That's not a typical Sensenich design number.

Are you sure the "0" in 690 isn't actually a "C"? Sensenich did make a 69C propeller for a 40 HP engine. It should be 69 inches long, not 72, though. You might re-check the length and the stamping for sure.

[FoolThrottle]

re:

Great catch, Dave! I thought it was strange that I could get any info on this number. But upon a much closer look, the stamp actually is 69C - not 690. That, of course, would make it the 69" variety (what's a few inches between friends?). I'll have to pull out the old protractor now to figure out the pitch.

If I'm reading it right, it looks like it may be one of these as posted on "modernwoodpropellers":

69C-23 Piper E 2 Continental A 40/40
Piper J 2, J 3, C40 Continental A 40/40

69C-26 Piper E 2 Continental A 40/40
Piper J 2, J 3, C40 Continental A 40/40

What do you think?

[Dave]

You're on the right track now. It might not be possible to go beyond that, however, as the propellers were really designed for the engine then applied to aircraft using that engine. But it certainly looks as if it was destined for a Piper Cub or one of its predecessors, maybe more likely to have been the E2 or J2.

If it is in original condition, it's always best to keep it that way.

[FoolThrottle]

I think I've covered a lot of ground with your help in a short amount of time. I'm not sure where to pursue this beyond what we believe my Piper-bound prop was once used for. The prop itself is in pretty good shape, considering. Whoever the owner/mechanic was, thought it would be OK to dab a little RTV on a couple of dings on the aft sides. Although it may have been slightly less than airworthy, it may have been the only economical way to keep it in productiion back in the day. I'm sure there is probably a little history, if not just an amusing little story for the "repairs." I read that props shouldn't be refurbed for a variety of reasons. So I decided to clean it up with a little bit of aliphatic naptha and dress it out with some linseed oil. I have mounted is at the hub mountholes (with what I think may be an original spinner) on a free-standing walnut stand that sits on top of my desk's hutch. It looks great and draws a lot of comments. Thanks for the input and if you have any other ideas on how to track down its history, please throw them my way.