The linked page from DARPA says: > Achieve cruise at speeds exceeding 400 knots Google tells me that a Boeing 737 flies (cruises) at 430–470 knots. Also,

The linked page from DARPA says: > Achieve cruise at speeds exceeding 400 knots Google tells me that a Boeing 737 flies (cruises) at 430–470 knots. Also, the A-10 Warthog only cruises at 300 knows. You wrote: > Not a substantial enough speed increase to powerfully deter air defenses. For modern air defenses like the Russian S-400 Triumf, pretty much all of their missiles can easily outrun (or catch!) any modern fighter jet. In your view, what speed would be "substantial enough"?