Planned JDAM Upgrade Boosts Accuracy to 10 Feet
An imaging infrared seeker that can improve the accuracy of the JDAM satellite-guided munitions by more than 200 percent has been tested successfully and is ready for production, said program officials. The same technology also could be used in other types of bombs and missiles.
The Joint Direct Attack Munition is a 1,000-pound or 2,000-pound free-falling bomb with a strap-on Global Positioning System/Inertial Navigation System (GPS/INS) guidance kit.
JDAM’s accuracy is nearly 43 feet in the GPS/INS mode and 100 feet with INS alone. The new seeker, using uncooled imaging infrared focal plane array technology, would increase the accuracy to about 10 feet. The system is called Damask, an acronym for direct attack munition affordable seeker. Each system is expected to cost $12,700, said Michael Dietchman, director of strike technology at the Office of Naval Research. Each JDAM guided bomb costs about $20,000.
Air-to-surface weapon accuracy is defined by circular error probable, or CEP. That is the radius of a circle within which 50 percent of the weapons will strike. The smaller the CEP, the greater the weapon’s accuracy. The JDAM CEP is 13 meters. Dietchman said that the addition of Damask to JDAM lowers the CEP to three meters (about 10 feet).
Three-meter accuracy is achievable with laser-guided bombs, which can only be used in clear weather with direct line-of-sight to the target, and require a dedicated designator. JDAM is less accurate but often a preferred choice, because it’s satellite-guided, so it works in bad weather.
The Office of Naval Research (ONR) developed and tested the Damask seeker and has turned over the system to Navy weapon acquisition officials. Damask could soon be used to upgrade JDAMs currently in production at the Boeing Co.
“The acquisition part of the Navy is working with Boeing to look at the design and where to go from here,” said Dietchman in a briefing to the Precision Strike Association. “The science and technology proved that it can work. Now it’s in the hands of the acquisition community.”
The Navy and the Air Force collectively could buy anywhere between 20,000 and 100,000 JDAMs during the next several years. These weapons were widely used in the 1999 air war over Kosovo and the campaign over Afghanistan this fall. JDAMs are compatible with Air Force B-2, B-52 and B-1 bombers, F-16C/D fighter aircraft, and with Navy F/A-18C/D fighter aircraft.
On the question on whether Damask could be viewed as an alternative to GPS, “one must be careful to distinguish between midcourse guidance and terminal guidance,” said Gil Graff, program manager for weapons science and technology at ONR. The Damask only is an alternative for terminal guidance. Guidance accuracy, he said, is limited by the capabilities of GPS and by the initial target location error (TLE). An imaging seeker such as Damask can achieve “substantial improvement in the final accuracy [compared to] inertially guided weapons,” said Graff.
He said he expects that this technology will have applications beyond JDAM. “While the initial focus of Damask was for JDAM improvement, we believe that the technology will support much smaller weapons—such as the Army Hellfire missile and the Air Force Small Smart Bomb and [other weapons] as small as 2.75-inch rockets.
“The real power of an imaging weapon,” he said, “is that it allows the munition size to be reduced substantially for a given level of damage.”
In his briefing, Dietchman noted that, if the GPS signal were jammed, Damask would be able to guide JDAM to the target nonetheless.
During tests last year, JDAM weapons, equipped with the Damask, successfully hit targets when the GPS signal was jammed, he said.
The Damask has been in development for three years. In 1998, the Raytheon Systems Co. received an $11 million Navy contract to work on the uncooled focal plane array technology. The detector in Damask is a thermal imaging IR camera produced by Raytheon for use in the night-vision system of the 2000 Cadillac Deville.
The upgrade kit includes a seeker mounted on the nose of the JDAM and processing electronics in the tail assembly.
Before a mission, an image of the target taken from infrared, visual, synthetic aperture radar, satellite photograph or other source is used to make a target template, which is loaded into Damask.
The target template can be created on a PC and loaded into Damask before aircraft launch. A template also can be downloaded to the aircraft from a reconnaissance unmanned aircraft or a satellite, or can be generated from the launch aircraft’s onboard sensors and loaded into the weapon during the mission.
For most of the mission, guidance is exclusively by GPS/INS. Then, when the weapon is a few kilometers from the target, Damask can be used to supplement GPS. It looks at the target for a second or two and compares what it sees with the target template that’s been loaded. If necessary, it updates the JDAM guidance unit.
A Damask prototype called GR-2 was tested a year ago at the Navy’s air warfare range in China Lake, Calif. The test was designed to duplicate a GPS-jamming scenario and measure the effect Damask would have in improving the JDAM accuracy, Dietchman said.
The launch platform was an F-16 Fighting Falcon from Edwards Air Force Base. Accompanying the shooter aircraft was a two-seat F-16 flying chase.
The pilot released the weapon at a slant range of about six miles, altitude of 28,000 feet (mean sea level) and speed of 0.8 Mach. From the point of launch, the JDAM received no GPS signals, navigating solely on INS. The GR-2’s target was a square aluminum plate. About 1,800 meters from the target, the Damask signal processor compared the target-area view through the IR seeker with a target-area template that had been loaded before flight, and then sent a correctional signal to the JDAM’s tail-control surfaces, said Dietchman. “Five seconds later, the weapon punched a hole in the target.”