High-fast made another brief return to the limelight in the early 2000s. Northrop Grumman's bomber studies focused on sortie generation over long distances. A supersonic aircraft cost more than a subsonic design, but could fly more sorties in the same period and deliver the first strike more rapidly. If the goal was to threaten fleeting targets over a wide area, each supersonic aircraft could hold a greater area at risk. One engineer argued, “You need fewer systems, because the question is 'Where can I be in 10 minutes?'”
Is high-fast worth reconsideration now? There are challenges. Speed makes it harder to search for and hit targets on the ground. It's costly, but whether it need be much more costly than a high degree of stealth is an open question. It means reviving investment in forgotten technologies.
The SR-72's Mach 6 goal will be hard to reach. But do we really need to go that fast? Mach 3-4, high altitude, situational awareness, reduced front-sector RCS and good electronic attack might be enough, and we could get there without resorting to ramjets.
But today's bomber studies are focused on stealth, and even the value of the F-22's speed and agility in dodging SAMs is not stressed today because awkward questions might follow concerning the survivability of slower, less maneuverable aircraft with a similar or slightly larger RCS. That is today's orthodoxy, more deeply entrenched than McNamara's faith in hedge-hopping.
As the 19th century humorist Josh Billings put it: “It ain't what a man don't know that makes him a fool. It's all the things he does know that just ain't so.”