This should be upvoted more, but I know HN prefers the binary explanations over ...

carabiner 4 months ago | parent | context | favorite | on: GE Aerospace Successfully Develops and Tests New H...

This should be upvoted more, but I know HN prefers the binary explanations over the accurate ones in aerospace. "Hypersonic" isn't strictly defined like supersonic. Hypersonic phenomena begin to manifest at around 3 mach.