Graham Warwick Washington and Guy Norris Los Angeles

Fifty years after the U.S. Air Force first began to recognize the true challenges of air-breathing hypersonic flight for weapons and aircraft, a cohesive plan is emerging that finally may enable those long-held goals to be achieved.

Unlike many earlier road maps, however, the new plan is measured in decadal, rather than annual, targets and appears to accommodate both the technological difficulties of the tasks and the realities of defense science and technology (S&T) spending in a time of austerity.

Despite the painfully slow progress from the days of the ramjet-powered Martin Marietta Advanced Strategic Air Launched Missile (Asalm) of the late 1970s to the most recent flights of the Boeing X-51A scramjet demonstrator, the plan recognizes that speed remains an Air Force priority for its warfighting capabilities.

The Air Force defense S&T vision now calls for efforts to support development of a hypersonic strike weapon by 2020, and a penetrating, regional intelligence, surveillance and reconnaissance (ISR) aircraft—probably piloted—by 2030. The service intends to achieve for strike weapons a technology readiness level (TRL) of 6, the jumping off point for full-scale development, by the start of fiscal year 2018. The target for a hypersonic aircraft is the far lower TRL 4 maturity level by 2020.

“Right now, the need is not necessarily there, but we can accelerate it if need be,” says Christopher Clay, deputy chief of the Science and Technology Div. of the office of the deputy assistant secretary of the Air Force for science, technology and engineering. The bottom line, he says, is that “one day, hypersonic capability will have to be an option for the U.S.”

The plan essentially funnels together the outcomes from a broad range of Air Force Research Laboratory (AFRL), Defense Advanced Research Projects Agency (Darpa), and other national and international efforts that have either ended, been canceled, are in process or in flux with uncertain funding. They range from the X-51A, with one more flight to go, to the canceled Darpa Blackswift, as well as related Facet combined-cycle and HiSted high-speed turbine engine technology demonstrations. Others include the US-Australian HIFiRE (hypersonic international flight research experimentation) fundamental research effort and AFRL robust scramjet.

“There were a lot of things going on at AFRL and none had critical mass. So we said, 'Let's pick two areas and see what progress we can make,'” says Clay. “Time-critical strike is on a pretty good pace, whereas the TBCC [turbine-based combined cycle] aircraft side is on a slower pace.” The outline plan “provides the basis for us to talk to other agencies,” he adds.