Unless the engine question is solved, I don't see any of the new wave of civilian SSTs (Boom, Spike, Aerion) going anywhere.
The airplane talk, let alone an SST, is pretty much all about the engine. So, with none of them putting an engine on the table, whatever else they do is, honestly speaking, pointless.
The airplane talk, let alone an SST, is pretty much all about the engine. So, with none of them putting an engine on the table, whatever else they do is, honestly speaking, pointless.
Be sceptical.