"Three years later, the agency and AFRL partnered again on the Hypersonic Air-breathing Weapon Concept (HAWC),
with multiple demonstrators achieving hypersonic speeds at unclassified ranges of more than 300 nm and altitudes above 60,000 ft."
Would sure like to know about that.
"The agency will consider options that are small enough to fit inside the internal weapons bays of tactical fighters.
But other concepts that come with weapons so large that they must be carried externally by a heavy bomber also will be considered. Offering a clue of the trade space, the concepts should come with flight test telemetry systems capable of tracking test missions at ranges between 250-2,500 nm, the RFI said."