Steve
The center ring is two aircraft carbon plate .050" thick. The carbon is thin enough so it can flex to help an arm absorb a bump. I'm using Heli tail booms now because their disposable and they break easily to protect the motor from bent shafts. A ribbon of nylon tape absorbs vibration so I don't need to balance the props. Works wonders.
I plan on moving the AQ board to the ring and have the center open for that ever I want to haul. Might take a little firmware mod to keep it flying as well as it does now. We'll see.
My brother-in-law farms in ND and his sunflowers fly away with blackbirds. I think too shotguns shooting in apposite directions would reduce recoil and really get after the birds. Best not to be too close when you fire!!
Larry