Air Force chasing speed

WASHINGTON – The U.S. military is quietly exploring hypersonic technology that would propel missiles or aircraft at up to six times the speed of sound – nearly 4,000 mph.

Known by code names such as Falcon, High Fire and Blackswift, the experiments and tests are being kept closely guarded as the Air Force looks toward a future generation of airpower and weaponry midway into the 21st century – or possibly sooner.

One possibility is an ultra-fast long-range bomber that the Air Force wants to field within three decades. Air Force officials hope to deploy a new interim bomber by 2018, followed by a more advanced, and possibly unmanned, bomber in 2035 that could incorporate many of the concepts emerging from current research.

Mark Lewis, the chief scientist for the Air Force, said a hypersonic cruise missile might be the first operational product to emerge from the research. Government teams, working with private contractors, also hope to develop long-range hypersonic aircraft that would take off from conventional runways, travel more than 10,000 miles in two hours and land on runways.

“We know there are other countries that are working on this technology,” Lewis said. “My goal is to make sure that the United States is the first country that ever brings this technology to the fight.”

Military analyst Loren Thompson, an executive at the Lexington Institute, a defense policy organization in Arlington, Va., said the Air Force “has great interest in long-range hypersonic vehicles that can do two things – collect intelligence and target time-sensitive assets.”

Thompson defined “time-sensitive assets” as “something that if you don’t hit right now it will be gone if you come back later.” He cited, as one example, a ballistic missile being prepared for launch against the United States.

The development of hypersonic technology has taken on new urgency after China destroyed one of its satellites 530 miles above Earth in a January 2007 test. The test raised fears within the U.S. government that a foreign power is capable of destroying military satellites in low Earth orbit.

“The Chinese and Russians have learned how to disable our spy satellites, so we need some way to avoid being blinded in a war,” said Thompson. “A really fast aircraft that could get over those countries right away would be a good backup to losing our spy satellites.”

The best known military plane that approached hypersonic speeds was the now-retired Air Force SR-71, which flew at 3.2 times the speed of sound. In 2004, an experimental hypersonic craft known as the X-43A tripled that speed, flying at Mach 9.6, or nearly 7,000 mph. The X-43 flights, however, were only seconds long, and scientists are trying to find ways to keep hypersonic craft airborne for long distances.

Much of the current work is being directed by the Defense Advanced Research Projects Agency, or DARPA, the arm of the Defense Department that’s responsible for advancing emerging technologies for military use.

The research involves hypersonic test vehicles, or HTVs, and is being carried out by government scientists working with contractors with a long history of top-secret research, including Lockheed Martin’s Skunk Works and Boeing Phantom Works.

Lewis, in a telephone interview, provided an overview of the research. The work appears to be the most comprehensive pursuit of hypersonic flight since the Reagan administration’s failed effort to build a national aerospace plane, nicknamed the Orient Express, that was intended to reach speeds 25 times the speed of sound.

Hypersonic vehicles essentially need two propulsion systems – a rocket or turbine to launch the craft, and ramjets or scramjets that obtain the hypersonic speeds but must be airborne before they can begin working.

A series of tests that will extend through next year involves the X-51 scramjet engine demonstrator, an unmanned vehicle that will be launched off the wing of plane in the same fashion that the X-43A made its record-setting flight. The test team consists of Boeing Phantom Works, Pratt & Whitney and the Air Force Research Laboratory at Wright-Patterson Base, Ohio.

Perhaps the most secretive is the Blackswift program, an extension of another program known as Falcon, a collaborative effort between DARPA and Lockheed Martin’s Advanced Development Products, the famed Skunk Works that developed the SR-71, the U-2 spy plane and the F-117 Stealth fighters.

The Falcon program aims at developing a reusable hypersonic cruise vehicle, HCV, capable of delivering 12,000 pounds of payload at a distance of 9,000 nautical miles, or 10,357 conventional miles, from the United States in less than two hours.

DARPA offered new details of the Blackswift tests in budget documents that accompanied the release of President Bush’s defense budget earlier this week. DARPA described the Blackswift tests as “an evolution” of the reusable HCV developed under the Falcon program. The goal, said DARPA, is to develop “enhanced-capability” high-speed vehicles for intelligence, surveillance, reconnaissance, strike “or other national need missions.”

U.S. officials also are working with Australian researchers in what Lewis described as “an extremely sophisticated” program to delve into the physics of hypersonic flights.

Those tests, known as High Fire, are being carried out at an installation in the Australian Outback and will feed into the X-51 and Blackswift programs.