When I assemble the Darter UAV e.g. on top of a small watchtower, where the little rim seams the area where the roof begins, then the UAV gets damaged or even destroyed. Same happens if you assemble it near another object, like a bucket.
Generally it seems too frail. I agree it shouldn't withstand multiple projectile hits, but it should be a bit more rigid specially during assemble/spawn. {F22521} {F22522} {F22523} {F22524}