U.S. military seeks global-reach bomber
By Andrew Bridges
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 deadly reach.
The Department of Defense 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 in Arlington, Va.
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 tremendous 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. "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 such engines.
Scramjets scoop oxygen from the atmosphere to combust fuel carried aboard. They can fly as fast as rockets but are lighter, since they don't have to carry both fuel and an oxidant to burn it, as rockets do.
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 as early as February, agency spokeswoman Leslie Williams said.
Days after the first NASA jet 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.
Scaling up the technology to the size needed to move an aircraft 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.
The disposable glider, and the 1,000 pounds of munitions it could carry, would hit targets at Mach 25, far faster than the more advanced hypersonic bomber. Mach 25 is as fast as the space shuttle travels when re-entering the atmosphere.
Pentagon officials envision the more advanced bomber version carrying up to 12,000 pounds of munitions, including cruise missiles.
That capability, coupled with the plane's speed, would free the military from relying on overseas air bases to station bombers capable of "promptly and decisively" striking enemies, according to DARPA.
The Pentagon can dispatch B-2 bombers from U.S. soil to strike anywhere on Earth but the missions can take a day and a half to complete.
Theoretically, a hypersonic bomber could be quickly scrambled and complete a similar mission over the course of an afternoon.
"It's a new capability," Poulos said. "It would be considered transformational in nature."