For years, Lockheed Martin has been developing a successor to one of the fastest aircraft the world has ever seen, the SR-71 Blackbird, the Cold War reconnaissance craft that the US Air Force retired almost three decades ago.
Lockheed officials have said the hypersonic SR-72-dubbed the "Son of Blackbird" by one trade journal-could fly by 2030.
But a rather curious talk last week at an aerospace conference by a Lockheed Skunk Works executive implied that the SR-72 might already exist.
Referring to detailed specifics of company design and manufacturing, Jack O'Banion, a Lockheed vice president, said a "digital transformation" arising from recent computing capabilities and design tools had made hypersonic development possible.
Then-assuming O'Banion chose his word tense purposely-came the surprise.
"Without the digital transformation the aircraft you see there could not have been made," O'Banion said, standing by an artist's rendering of the hypersonic aircraft. "In fact, five years ago, it could not have been made."
Hypersonic applies to speeds above Mach 5, or five times the speed of sound.
The SR-71 cruised at Mach 3.2, more than 2,000 mph, around 85,000 feet.
Computer processing power and new tools allow for three-dimensional design of a scramjet engine, O'Banion said at the American Institute of Aeronautics and Astronautics' annual SciTech Forum near Orlando. (Scramjet refers to engine combustion occurring at supersonic speeds, which adds to the engineering complexity.)
Adding a little Hollywood to an engineering presentation, O'Banion likened the digital advances in 3D-design to the build process Tony Stark employs in the film "Iron Man."
"We couldn't have made the engine itself-it would have melted down into slag if we had tried to produce it five years ago," O'Banion said.
"But now we can digitally print that engine with an incredibly sophisticated cooling system integral into the material of the engine itself, and have that engine survive for multiple firings for routine operation." The aircraft is also agile at hypersonic speeds, with reliable engine starts, he said. A half-decade before, he added, developers "could not have even built it even if we conceived of it."
Of course, none of the Skunk Works executive's talk confirmed that Lockheed Martin is preparing to turn over to the Pentagon a top-secret hypersonic aircraft, nor does it reveal how far the project may have progressed. It's also unclear if such an aircraft would carry pilots or operate as a drone.
(Skunk Works is the name of Lockheed's 75-year-old advanced development programs division, based in California.)
Lockheed declined to address O'Banion's comments. The defense contractor "continues to advance and test technologies which will benefit hypersonic flight," spokeswoman Melissa Dalton said in an email. "A Reusable Hypersonic System (RHS) is a far term solution that will be made possible by the path-finding work we are doing today."
An Air Force spokesman, meanwhile, said only that that the military has no information on the project "at this time."
Talk about Lockheed's hypersonic program isn't new. In fact, executives discussed the program's status to such an extent last June that defense reporter Tyler Rogoway called it "highly peculiar." (His article was headlined "What's the Deal with Lockheed's Gabbing About the Secretive Hypersonic SR-72?")
"There's probably a big distance between prototype development and actual operational capability," said Richard Aboulafia, a defense analyst with Teal Group. And the military has a history of publicly revealing new advanced aircraft many years after their prototypes were delivered.
Nevertheless, the SR-72 work could be an entirely digital exercise to date, funded by ample "black budget" appropriations stretching into the billions of dollars over time, Aboulafia said. It's also possible that any hypersonic capability may well be incorporated into a new type of long-range missile before an actual aircraft.
The basic physics of hypersonic flight have been understood for decades, with the Air Force and NASA flying the rocket-powered X-15 in the 1960s above Mach 6 and the X-43A hitting Mach 9.6 in 2004. More recently, Boeing Co. flew an experimental craft, the X-51 WaveRider, to Mach 5.1 in May 2013.
Still, there are myriad design challenges involved with hypersonic projects, Aboulafia said, likening scramjet engineering hurdles to "the proverbial lighting of a match in the hurricane." This is one reason no hypersonic aircraft are in military service today-although U.S. officials have expressed concern about Chinese and Russian ambitions employing the technology.
For the Pentagon, such speeds would represent a new form of strategic deterrence in the sense that a hypersonic bomber could penetrate an enemy's airspace, fire and depart before that nation had time to react. Aboulafia noted, however, that such a capability could also be considered a destabilizing development if a U.S. adversary decided to react preemptively to such an aircraft's existence.
The specific need is also unclear, given advances in satellite surveillance capabilities and the planned B-21 Raider, a precision bomber from Northrop Grumman Corp. expected to replace the Air Force's aged fleet of B-1 Lancers adn B-52s. The B-21 could cost as much as $133.6 billion for production and maintenance of at least 100 planes, with the first expected in the mid-2020s.