After a crash, two of the arms on my 3DR Hex shifted slightly. Enough that the props overlapped. I didn't notice it for a while, but on a subsequent flight, they prop tips touched. The hex didn't crash but the noise it made certainly got my attention.
My solution was to add more sonar mounting brackets to beef up the arm placements. It also gave me more places to mount stuff. (Copter is upside-down in the photo).
Comments
Eric, with 12-inch props there's 10mm clearance between tips.
To save weight (I like to keep things as light as I can) you might consider a perimeter wire or string or cord or something. There's a fancy engineering term for the tensioning device like on the Astrodome to keep the walls from falling outward. Stretch it around the ends of the arms. Carbon fiber rods would be nifty; just need to figure a way to attach them.
What is the clearance between the prop tips while stationary?
I am wanting to go to inrease prop size but I am also concerned about flex