SmithsJunk
In Bloom
Working on depmotor tubing today.lookimg at the greenhouse i may have to deflate the 2 layers. The outer may hold the curtain out too far. I'll post some pick on my log when I get there.
As long as there's no light leaks, space in between makes zero difference. To keep the blackout fabric tight run ratchet straps over the top and attach to heavy duty bungee cords at the ends. When you make the vertical poles for the motors set them up as a sleeve with an inner and outer pole. That will give them the ability to extend and contract. Combined with the straps the floating arms will stay tight to the frame.
Being attached at a single point equalizes the weight of the arm preventing the loosening of the anchor and simplifying the system with a single anchor point.