Ever since Lockheed’s unsurpassed SR-71 Blackbird was retired from U.S. Air Force service almost two decades ago, the perennial question has been: Will it ever be succeeded by a new-generation, higher-speed aircraft and, if so, when?
That is, until now. After years of silence on the subject, Lockheed Martin’s Skunk Works has revealed exclusively to AW&ST details of long-running plans for what it describes as an affordable hypersonic intelligence, surveillance and reconnaissance (ISR) and strike platform that could enter development in demonstrator form as soon as 2018. Dubbed the SR-72, the twin-engine aircraft is designed for a Mach 6 cruise, around twice the speed of its forebear, and will have the optional capability to strike targets.
Guided by the U.S. Air Force’s long-term hypersonic road map, the SR-72 is designed to fill what are perceived by defense planners as growing gaps in coverage of fast-reaction intelligence by the plethora of satellites, subsonic manned and unmanned platforms meant to replace the SR-71. Potentially dangerous and increasingly mobile threats are emerging in areas of denied or contested airspace, in countries with sophisticated air defenses and detailed knowledge of satellite movements.
A vehicle penetrating at high altitude and Mach 6, a speed viewed by Lockheed Martin as the “sweet spot” for practical air-breathing hypersonics, is expected to survive where even stealthy, advanced subsonic or supersonic aircraft and unmanned vehicles might not. Moreover, an armed ISR platform would also have the ability to strike targets before they could hide.
Although there has been evidence to suggest that work on various classified successors to the SR-71, or some of its roles, has been attempted, none of the tantalizing signs have materialized into anything substantial. Outside of the black world, this has always been relatively easy to explain. Though few question the compelling military imperative for high speed ISR capability, the astronomical development costs have made the notion a virtual nonstarter.
