[ghaff]

Designing airframes isn't easy but aren't really novel. This is about coming up with engines that don't have noise concerns and have economics that would allow airlines to operate aircraft at prices that aren't that out of line with current ticket prices. It's not at all clear how big the market is for very premium tickets for supersonic travel is transatlantic and transpacific has a bunch of other range issues.

[hef19898]

Conventional airframes are not novel, building an aircraft is still incredibly hard so.

Civilian super sonic airframes so are novel, nobody did that since the days of the Concord and its Tupolev clone.