Mike,

I can only say in my experience, I've not seen an APC-E show the effects of age in terms of fatigue or tip tracking. Personally, I don't think I have many E props with more than 100 flights, and none with 200 (compared to some glow stuff where I have many props at 300, 400, 500+ flights). I know many years ago, APC had some prop tips fail in large scale warbird pylon. To recall the problem was traced to a resonance generated by one of the engines being used (a more common one to recall), and I believe the design of the prop was changed. To this day, APC has an advisory regarding resonances in airframes/motors/etc on their website.

I agree 100% with the discussion presented by Brenner. The suggestions I made regarding motors and mounting motors is derived from experience only, and I am sure Brenner could advise as to the difficulties of attempting to model/calculate various resonances of motors and mounts in various fuselages (of vastly differing construction quality and materials).

One item I forgot to mention, that ties in with what Brenner noted, is that I highly recommend using the plastic centering rings that come with the APC props. As is detailed in the APC instructions and on the APC website, the pilot hole in the prop is not a precision hole, but the larger recessed/countersunk hole on the backside is a precision surface and the use of the centering rings is required to ensure the prop is centered on the propshaft. Opening up the pilot hole from the front with a tapered reamer ensures that the prop does not try to bend the prop shaft. http://www.apcprop.com/v/html/tech_s...html#holealign Quite honestly, I never noticed a problem with the pilot hole when running glow, but I have a number of electric installations that appear very critical to prop balance. Balancing the prop should be done with the centering ring in place. For motors that require the prop to be drilled to a larger diameter than the biggest centering ring, I jig the prop in a drill press, centering it using a drill bit that just fits inside the centering ring. Then I put in a larger drill bit to open the hole in the prop. If, after opening the hole in the prop, it is no longer balanced, then the hole is offcenter and the prop should be discarded.

Again, no argument here, just trying to share information and learn what can be learned, and progress forward for all.

Regards,

Dave