Extreme hypersonic flight at Mach 20 - or 20 times the speed of sound - would enable the Pentagon to deploy troops anywhere in the world in under an hour.
However, achieving speeds of Mach 20+ for an extended period of time has understandably eluded researchers for decades.
At Mach 20, vehicles flying inside the atmosphere experience intense heat, exceeding 3,500 degrees Fahrenheit, which is hotter than a blast furnace capable of melting steel. And unlike subsonic aircraft equipped with external probes measuring air density, temperature and pressure of surrounding air, vehicles traveling at Mach 20 are currently incapable of fielding (functional) external probes.
Nevertheless, the US Department of Defense (DoD) has managed to obtain vital information about developing ultra-fast aircraft as the Pentagon continues to eye a hypersonic future.
"The DoD's hypersonic technology efforts have made significant advancements in our technical understanding of several critical areas including aerodynamics, aerothermal effects, [along with] guidance, navigation and control," explained acting DARPA director Kaigham J. Gabriel. "But additional unknowns [still do] exist."
According to Gabriel, tackling 'remaining unknowns' for the DoD is the focus of the new DARPA Integrated Hypersonics (IH) program.
"History is rife with examples of different designs for 'flying vehicles' and approaches to the traditional commercial flight we all take for granted today," he said. "For an entirely new type of flight - extreme hypersonic - diverse solutions, approaches and perspectives informed by the knowledge gained from DoD's previous efforts are critical to achieving our goals."
To accelerate the DoD's initiative, DARPA plans to solicit proposals for advanced Mach 20+ designs. Ultimately, the DoD wants to supervise a test flight of a full-scale hypersonic X-plane (HX) by 2016.
"HX is envisioned as a recoverable next-generation configuration augmented with a rocket-based propulsion capability that will enable and reduce risk for highly maneuverable, long-range hypersonic platforms," added Gabriel.