ORIGINAL: John Stainforth
In fact, the manual recommendation for the Katana 50 is pretty much the ''reversing the mechanical advantage'' you describe in your second paragraph.
I went back and looked at my manual, and indeed you are correct in regards to the aileron servos. The suggested elevator set-up is not as "radical".
Since I'm using servos far stronger than those called for (they came out of a 30% gasser), and my linkage set-up is an IMAC style (reduced servo throws via a small servo horn), and I sealed my hinge lines as a matter of course, I expect no such flutter issues on my model.
If I were you, I'd seal my hinge lines as well. All that beefing up you did will be to no avail if the aileron flutters as a result of surface blow-by and wrecks your servo. No, this wasn't called out for in the manual; but my kit included several strips of transparent adhesive-backed material for that purpose. I always use clear UltraCote or MonoKote for this chore, however.
At any rate... good luck with your model. I thoroughly enjoy mine.
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