Ah, much thanks
@UhClem. I have quite a vibration/natural frequency analysis background, but as I noted in the file, he runs into the same issue - material properties. Composites (layered materials), wood, etc. can be right devils to get any reasonable property values for; they are directional, non-isotropic, all that nasty stuff that makes even a finite element analysis a question mark. Throw in soaking balsa in CA or papering fins, birch plywood, etc. and Houston, we have a problem (most overused line on the forum, likely...) There may be a way around it by test, but even that takes special equipment, and while I do have access to some of it, I need to consider how I'd do it. We're supposed to be getting a non-contact (laser) pickup, and that could be
really useful. Twang a sample piece of material, get the cantilever frequency, back in some material properties, and a lot of progress could be made. But then you get into that NACA paper, which I haven't looked at yet. Fluid mechanics correlations can be ... interesting!
I noticed a database of cases in the sheet where fins shredded, survived, etc. Very interesting! Of course it is possible to get through a resonance depending on the damping and how fast you can accelerate through it, etc. as is done with rotating machinery a lot.
ETA:
@Banzai88, is the onwer you mentioned the fellow listed here? -
https://www.aerorocket.com/finsim.html
The name sure seems familiar and it sure looks like he's done a better job than me starting from that spreadsheet and the NACA paper.
ETA AGAIN: Holy Smokes, John has a resume that is over-the-top for this application! So the OP is noting that John has stopped distribution in the US, then. I'm kinda slow on the uptake; please forgive me.