>>64476839
Not him.
> Delta wings are godawful efficiency wise in subsonic flight
It's highly dependent on altitude, the cruise altitude for a delta is lower, the problem are the engines.
And supersonic flight is far worse with any wing shape. The SST concept was created during the 1950s when HPR turbofans weren't common and it was competitive against slow and not so aerodynamic planes using turbojet engines (that are less efficient than a properly designed supersonic cruise turbojet) or very low BPR turbofans.
As long as a SST has to carry its own fuel it will never compete against a SubST.