QUOTE (Bill Harris @ Feb 28 2024, 11:31 PM)
It can be hard to say or visualize what a copter blade will do when impacting soft substrate at a low angle.
The interaction of the striking blade tip with the sand ripple, and its direct local effects on a composite structure, are indeed not well-constrained.
However, I suspect it is the other blade of that rotor that broke and was flung away. You can see this happen on lots of youtube videos of helicopter crashes, notably those where the blades hit water. The sudden angular deceleration of the rotor causes a huge bending moment at the root of the other blades, which feel strong compulsion from Newton's First Law.......