I decided to give the x447 prop a try on my stock electronic spartan a few weeks ago. It runs like a champ and blows all of my other props out of the water. But after about the 5th time out I noticed what seemed to be a LVC at full throttle. It turned out to be the flex shaft spinning inside of the coupler as eventually it let loose. I have an aluminum motor cooling jacket, I have opened up the single water inlet (on rudder), added an additional cap on the ESC, and changed the connectors out to the EC5's. I also have only ran this prop on Thunder Power 65c/130c 5000mah 6s lipo's (dual 3s). I have zero problems with heat.
I never got around to asking, but if I had issues with the Jeff Wohlt .150 flex shaft slipping in the Aquamarine 3 pc coupler with the x447 prop wouldn't have that been an issue even if I had a different motor/ESC? Or should I be running the .187" flex shaft with this prop?
I'm also thinking due to the length of my run that I jammed into full throttle a bit too soon in which the prop just had a bit too much drag which led to the flex shaft slipping.