After the collapse of the Soviet Union during the dawn of the1990s, the U.S. Air Force decided to convert its B-1B nuclear bombers to a conventional warfare role. The planes were developed in the 1970s and may continue service for another 30 to 35 years. So, nearly 10 years ago, the service launched the Conventional Mission Upgrade Program (CMUP), which continues today. Among the avionics high points are a major computer hardware and software update, GPS-aided navigation, voice radio upgrades and new electronic countermeasures (ECM) capability. Situational awareness also is improving, in a gradual, "non-integrated" manner, driven by the use of guided bombs like the Joint Direct Attack Munition (JDAM).
The B-1 program is in the unique, if unenviable, position of funding many of its upgrades with existing assets–a "heal thyself" measure, as program manager, Col. Mike Miller, describes it. "There’s a $2-billion backlog of things we’d like to do to B-1 for [enhanced] survivability, lethality and sustainability." The service is consolidating from 92 to 60 aircraft next fiscal year and reducing its B-1B infrastructure from five bases to two, moves that will save the program $850 million.
CMUP now comprises four phases, Blocks C through F, contracted to Boeing (see sidebar, page 28). Additional steps, such as radar and cockpit display upgrades, are contemplated but have not been defined. Blocks C, D and E added, or will add, new weapons capabilities. Block D also added the ALE-50 towed decoy system, the Mil-Std-1760 weapons bus, GPS for both aircraft and weapon navigation, and upgraded communications. Block E required a major hardware and software processor upgrade. Block F focuses on defensive avionics.
Block D aircraft in Afghanistan, fitted with GPS-guided JDAMs and towed decoy systems, have dropped more than 3,800 of the weapons, "more than all other airplanes combined," says Richard Parke, Boeing’s director of advanced projects and business development for B-1. Although the aircraft, as of April, had flown only 5 percent of the strike sorties in Operation Enduring Freedom, they accounted for more than 40 percent of the ordnance placed on target.
New Computers
The computer upgrade in Block E will enable B-1Bs to carry three additional weapons: the Wind-Corrected Munitions Dispenser (WCMD), the Joint Standoff Weapon (JSOW), and the Joint Air-to-Surface Standoff Missile (JASSM). The faster computers and new software also will allow the aircraft to launch multiple weapon types against multiple targets in a single sortie, a concept called weapons flexibility. Block E is expected to enter production in mid-FY 2003.
Six legacy computers–covering controls/displays, guidance/navigation, weapon delivery, critical resources function and terrain following–will be replaced by four new computers. The new processors will increase memory capacity, throughput, input/output bandwidth, growth potential, and reliability/maintainability.
The four new processors are largely similar. They move from 0.8 MHz to 300 MHz in processing speed and from 256 kilobytes (Kbytes) of antiquated magnetic core memory to 128 megabytes (Mbytes) of RAM–maintaining about 300 percent spare capacity. The new main avionics computer supports controls/displays, guidance/navigation, weapon delivery and mission management, a job that required three computers before. A second computer supports terrain following. And both computers have hot spares. Although the 6U VME-format processor boards are supplied by Lockheed Martin, they contain commercial off-the-shelf (COTS) elements, such as an 80-Mbyte/sec VME backplane and 300 MHz PowerPC chips. Each computer has two boards, each with 64 Mbytes of RAM.
Avionics flight software for basic navigation, controls/displays and mission management–written in the 1970s Jovial programming language–was converted to modular, Ada95 code. The weapons software, however, "was rewritten from scratch" in Ada95, using an object-oriented architecture, says Lt. Col. Gordie Neff, Block E program manager. This will make it easier to add new weapons, he says. The processor will have been upgraded three times in the course of the program.
In addition, the Air Force will replace the current data transfer system (DTS), the cartridge used to transfer mission data from the mission planning ground station to the aircraft. The current DTS is a complex and slow, nine-track tape, Neff says. The first redesign was a military-unique, 110-Mbyte mass memory device. But now the program office has decided to use COTS PCMCIA cards with ruggedized, industrial-grade receptacles. This approach could reduce costs in this area by a factor of 40, Neff says. He expects to complete system integration this fall, with production installations in 2003.
Bombs Away
In early May the Air Force completed a service "first," launching three weapon types against three targets in a single, 20-second bomb pass. Munitions included one Mk-84 (2,000-pound [907-kg] gravity bomb), three Mk-82s (500-pound [227-kg] gravity bombs) and four, unguided CBU-89s (1,000-pound [453-kg]-class cluster munitions). The targets were about 10,000 feet (3,048 meters) apart. Without Block E, this action would have required three bomb passes or a coordinated strike by three aircraft, Neff says.
On August 10 was the coup de grâce–the launching of a mix of guided and unguided weapons against four targets in a single bomb run. Two JDAMS were in the forward bay; six "dumb" Mk-82s, in the mid-bay; and two WCMDs, in the aft bay, Boeing says. Installation of the weapons flexibility upgrade–part of the weapons delivery software–is to conclude in 2005.
In the early 1990s, it was said that Boeing charged $200 million every time the Air Force put a new bomb on the airplane, Parke remarks. "That was because the computers were full–we basically had to rewrite all the code" when new weapons were added. With the new computers and software, JASSM and JSOW will be integrated for a total of $48 million, Boeing says.
Situational Awareness
As the aircraft’s conventional warfare capabilities have increased, situational awareness has become an issue. B-1s need to pursue mobile targets and targets of opportunity, as well as fixed targets programmed into the avionics before takeoff. Efforts started in 1995, with the demonstration of a beyond line of sight (BLOS) data link, Parke recalls. New targeting data, presented in text and image files, was transmitted via satellite to the B-1B en route and then was entered manually into the bomber’s offensive avionics suite.
An updated version of this system, with new Combat Track II UHF satcom radios, was flown in an Air Force exercise in 1998. A temporary, onboard, Unix-based computer, running the multisource tactical system (MSTS) application, received GPS inputs and combined them with moving map, terrain and threat data. The unit calculated the aircraft’s position on the moving map and transmitted position data to a dedicated ground station. New targeting data was fed into the MSTS computer from the Track II system, which also provided crews two-way e-mail communications.
The addition of JDAMs in Block D further concentrated attention on situational awareness. If the aircraft carried 24 JDAMs, as it can today, each JDAM has a different target at a different location along the route. The JDAM’s launch acceptability region (LAR)–the airspace segment in which the weapon should be launched in order to hit its target–changes constantly as the aircraft maneuvers or retargets to counter new threats. LAR calculation incorporates factors such as aircraft dynamics (speed, altitude, winds), weapon requirements (glide ratio, impact angle, fusing), and targeting requirements (horizontal, vertical, on/off-axis), Parke explains. The crew needs improved tools to visualize all of these LARs, to ensure that all of the weapons can reach their targets, a Boeing engineer adds.
In the 2000 timeframe, some B-1B crews added "Falcon View" software, developed for the Air Force by Georgia Tech, to laptops installed near the backseats, Parke says. In addition to some route planning features, the program can overlay aircraft position on a moving map, given a GPS feed. A subroutine called "Busy JDAM" looks at target information input by the crew and uses it to display the LAR on the moving map.
The frontseat displays provide steering cues enabling the pilot to reach the LAR area. But the legacy monochrome displays are unable to provide an intuitive representation of the LAR drop zone relative to the aircraft and surrounding terrain, Parke says. So the weapons officer, using the backseat display, verbalizes steering commands to the pilot, to keep the plane in the LAR, as the area changes in shape and size. A front seat color display would ease the demanding crew coordination requirements.
Last year, some B-1B flight crews added Fujitsu kneeboard computers in order to show situational awareness information in the front cockpit, Parke says. A number of aircraft have used this setup in Operation Enduring Freedom in Afghanistan. The BLOS data link was used to track the planes’ position and provide new targeting data in text format. Voice radios also provided target data, which was entered on both the laptop and the kneeboard computers, helping crews to reenter their LARs as the launch areas changed.
Crews manually enter new target coordinates, waypoints, fuel factors and LARs into the offensive avionics system, which also calculates the LARs to drop the weapons. The laptop software is not coupled to the onboard avionics computers, "but it helps the crews to get the aircraft in the right position for the bomb to fall," Parke says. When the aircraft senses it’s in the right position, it automatically drops the ordnance.
The Air Force has asked Boeing to wire 36 aircraft to be able to use a kit including the two computers, moving map and radio. (The kits would be movable between properly provisioned aircraft.) Boeing is to complete the work by December 2002, Parke says. The company also is increasing the bandwidth of the "non-integrated," BLOS radios in use on some planes from 5 KHz to 25 KHz and wiring the radios to existing aircraft antennas, he says. However, the radios are not interoperable with coming systems such as Joint Tactical Radio System, so they eventually will have to be replaced.
Data Link
A separate effort, called Interim Data Link (IDL), is proceeding at the Oklahoma Air Logistics Center, Parke says. Although similar to the BLOS system, the IDL uses fixed, front seat displays and incorporates a Class II, Link 16 terminal. This additional data link will allow B-1s to connect into the line of sight, Link 16, C3I networks used by Air Force and Navy fighters.
While the current aircraft displays are suitable to the current missions, they are not suitable to future missions using additional data links and increased data link integration, says Lt. Col. Mike Scifres, chief of the B-1 Projects Division in the B-1 program office. Data link evolution will be a driver of how the information will be presented, he says.
The third major step is the Defensive System Upgrade Program (DSUP), an element of Block F, now in development. Block F could reduce B-1B ownership cost by 10 percent and ECM system ownership cost by more than 80 percent, Boeing claims.
Block F removes most of the existing AN/ALQ-161 defensive system, replacing it with an upgraded AN/ALR-56M radar warning receiver and the RF countermeasures portion of the Navy’s Integrated Defense Electronic Countermeasures (IDECM) program. The effort will reduce the line replaceable unit (LRU) count from 120 to 34, Miller says. The Air Force expects a decrease in weight from 5,200 pounds to 1,000 pounds (2,268 to 453 kg) and an increase in mean time between failures (MTBF) from 13 hours to 147 hours, he adds. IDECM comprises the onboard AN/ALQ-214 receiver modulator processor, including a techniques generator, and the ALE-55 fiber optic towed decoy (FOTD). (Techniques are RF signals that can deceive enemy radars regarding an aircraft’s position, angle, range and velocity.) The aircraft also has the inherent capability to perform some barrage jamming, swamping an enemy radar receiver with RF noise.
Towed Decoy
"There have been some aeromechanical problems [with the FOTD] in deploying and maintaining fiber optic continuity," says Mike Eviston, the Air Force’s Block F chief engineer. (Fiber optic continuity is the ability to transmit a signal through the fiber and have it received at the other end.) These aerodynamic, mechanical problems include issues with the decoy’s offboard cable deployment mechanism, compression ring and the termination connection point, where the towline attaches to the decoy.
Backup Plan
As the Air Force and Navy work on these issues, they are considering backups, such as modifying the current AN/ALQ-161 electronic warfare system, Eviston says. A production decision is expected in the second quarter of FY 2004.
The Air Force, meanwhile, is believed to have invested more than $4 billion in the AN/ALQ-161. Recently, the Warner Robins Air Logistics Center awarded EDO Corp. an $11.4-million contract to provide continuing support and performance improvements on the AN/ALQ-161 for the B-1B. The electronic defense system is "a candidate for continued upgrade and support improvements for the life of the B-1B," says James Smith, EDO Corp.’s chairman and chief executive officer.
But for now, despite the risk in the IDECM approach, it remains the only FOTD available, Parke says. Of note, the ALE-50 broadband jammer required 200 shots to make the cable work, and the ALE-55 has had only about 90 shots–eight or nine of them on the B-1B, he adds. The advantage of fiber optics is "you can get the techniques down [to the towed decoy] instantaneously."
The ALR-56M, "the ears of the system," is working well in integration testing, says Parke. The system has been married to the aircraft avionics and tested on the ground against multiple threats. Risk reduction flight tests have been proceeding since August 2001 on the B-1, primarily for ALE-55 safe separation and envelope expansion. They are expected to continue until next spring, says Lt. Col. Peter Knudsen, Block F program manager.
Radar Upgrade?
The B-1B’s radar system, a 1970s derivative of the F-16’s sensor, also needs modernization. Since then, the F-16 system has been upgraded nine times, but the B-1 hardware has not, Parke says. The B-1 system’s 10-foot (3-meter) resolution is not sufficient, alone, for complex, evolving tactical environments.
Currently, spotters on the ground are used to overcome the discrepancy. In the synthetic aperture radar (SAR) mode, the B-1B can take a picture of a 4,000-square-foot (372-square-meter) area on the ground at 10-foot resolution, says a Boeing engineer. This resolution is not high enough to allow the crew to distinguish between an 18-wheeler and a tactical ballistic missile launcher, or between a tank and a school bus, he says.
The B-1B today can track only one moving ground target. "This is not sufficient for an aircraft capable of carrying as many as 30 smart munitions and capable of successfully engaging hundreds of moving targets," the Boeing engineer says. "In the future, with small munitions under development, the B-1B could carry hundreds of moving target attack munitions." An upgrade of the radar could enable the bomber to track dozens of targets.
The radar modification would increase resolution to 1 foot (0.3 meter), while slightly increasing the size of the picture, the engineer says. It also would provide software to assist the crew in rapidly recognizing and locating targets.
These capabilities may be available in five years. There was originally about $200 million targeted for the radar upgrade, but the true cost approaches $800 million, according to Boeing. So the project may be postponed to the out years.
B-1 Conventional Capability Upgrades
Block C
Block C, which became operational in September 1997, added the ability to carry the following weapons:
Combined Effects Munition, CBU 87–a wide-area, anti-armor, -personnel and -material weapon that dispenses 202 submunitions;
CBU 89–an area denial cluster munition for use against personnel, armor and support vehicles; and
CBU 97–the Sensor Fused Weapon (SFW), which dispenses 40 "skeet" warheads for wide-area attack of armor and support vehicles.
Block D
Block D, which is now in production, adds:
Joint Direct Attack Munition (JDAM)–enabling precision strikes deep in enemy airspace, and
ALE-50 towed decoy system.
Under Block D, the bombers also have been equipped with the Mil-Std-1760 weapons bus, GPS for aircraft and weapon navigation, and upgraded communications.
Block E
Block E includes a computer upgrade to add flexible targeting, the use of multiple weapons in a single sortie. As of August, this phase was completing developmental test and the first parts of operational test and evaluation (OT&E). Full OT&E is to begin in September 2002, followed by a production decision in spring of 2003. Weapons include:
Wind Corrected Munitions Dispenser (WCMD), 10 per bay or 30 per aircraft;
Joint Standoff Weapon (JSOW), a GPS-aided INS guidance, unpowered munition, four per bay, or 12 per aircraft; and
Joint Air-to-Surface Standoff Missile (JASSM), with automatic target recognition/seeker system and GPS/INS guidance, 1,000-pound-class penetrating warhead with blast/frag capability, eight per bay or 24 per aircraft.
Block F
The Block F defensive avionics upgrade includes:
AN/ALR-56M radar warning receiver;
ALE-55 fiber optic towed decoy; and
ALQ-214 receiver modulator processor.