Robotic bomber plans in the works

LOS ANGELES — It is the latest in the U.S. military’s quest for faster, more lethal, remotely operated weaponry — an aircraft that could bomb targets anywhere on Earth within a scant two hours of taking off from the United States.

The robotic bomber would streak eight times the speed of sound and have a 20,000-mile range, putting the entire globe within its reach.

The Defense Department and the Air Force are jointly sponsoring the program, known as Force Application and Launch from the Continental United States — or Falcon.

"The bottom line is, what we want to be able to do is have the capability to strike anywhere on the globe in less than two hours," said Jan Walker, a spokeswoman for the Defense Advanced Research Projects Agency, or Darpa, in Arlington, Va.

Darpa and the Air Force recently selected the program’s first contractors, a 10-company list that includes Northrop Grumman Corp., Lockheed Martin Corp. and Orbital Sciences Corp.

The earliest such a reusable hypersonic aircraft would enter operation is 2025. However, simpler versions of the vehicles, including one designed to carry small satellites to orbit, could be flying within the decade, officials said.

"What we’re talking about is decades of drawings and prototypes," said Richard Aboulafia, an aerospace industry analyst at the Teal Group in Fairfax, Va.

Huge technological hurdles remain, including the development of the exotic materials needed to protect the airplanes from the heat generated during hypersonic flight. How to propel, steer and communicate with the aircraft is also unknown.

"They are going to be a stretch from a technology standpoint, but there is no reason why they can’t develop and deploy them. There is no ‘unobtainium’ in them," said Dennis Poulos, Northrop’s Falcon program manager in El Segundo, Calif. Unobtainium is an imaginary material engineers jokingly invoke in presenting otherwise unobtainable solutions to problems.

Key to the project is the development of an air-breathing engine called a scramjet. Both Darpa and the National Aeronautics and Space Administration are working on the exotic engines.

Scramjets, or supersonic combustion ramjets, scoop oxygen from the atmosphere to combust fuel carried aboard. They can fly as fast as rockets but are lighter because they don’t have to carry both fuel and an oxidant to burn it, as do rockets.

However, scramjets must be traveling at about five times the speed of sound to work. That requires the use of a rocket to initially get them up to speed.

In June 2001, a NASA demonstration flight of a scramjet vehicle failed when the rocket used to accelerate it began to fall apart and veer off course.

NASA hopes to test its second scramjet-propelled X-43A next year, perhaps in February, agency spokeswoman Leslie Williams said.

Days after the NASA demonstration flight failed, Darpa successfully launched a 4-inch-diameter titanium mock-up of a missile powered by a scramjet, in what it said was the first-ever free flight using the technology. The projectile covered 260 feet in just over 30 milliseconds. Darpa later repeated the feat.

Scaling up the technology to the size needed to move an aircraft at hypersonic speeds will be challenging.

Before building a hypersonic bomber, the Pentagon seeks to develop a smaller, unpowered glider that could still fly at mind-numbing speeds. A modified version could ferry small satellites to space.

"That’s more doable in the near term," Walker said.

The tactical version of the steerable glider would be accelerated using a rocket, perhaps in combination with a scramjet, and then released to plummet back to Earth on a one-way trip to its target. Its range would allow it to hit targets the world around.