The B-2 Bomber required low-level, terrain following performance. The B-2 included a very complex Terrain Following/Terrain Avoidance (TF/TA) system that integrated the forward looking radar subsystem, flight control computers, navigational computers and cockpit displays. Before low-level flight testing could begin, the airworthiness of the system had to be reviewed and certified safe for flight. An Executive Independent Review Team (EIRT) was established to review the B-2 TF/TA system. The review team was made up of EN and Air Force Research Laboratory experts. EIRT engineers conducted a thorough review of the TF/TA system, primarily to make the system fail-safes more robust. The EIRT engineers also provided valuable lessons learned from previous aircraft systems such as the B-1, F-16 and F-111. The B-2 Program Office engineers, working with the contractor, implemented many of the EIRT recommendations. The organic engineering expertise of the EN EIRT and ASC Engineering Program Office engineers, along with the contractor team, combined to create a TF/TA system for the B-2 which has proven safe in both flight test and operational use.
Link-16 - Providing Line-of-Sight (LOS) data for aircraft-to-aircraft, aircraft-to-C2, and aircraft-to-sensor connectivity, Link-16 was intended as a combat force multiplier that would provide US and other allied military services with fully interoperable capabilities and greatly enhance tactical Command, Control, Communication, and Intelligence mission effectiveness. Link-16 provides increased survivability, develops a real-time picture of the theater battlespace, and enables the aircraft to quickly share information on short notice (target changes).
Connectivity - DoD required survivable communications media for command and control of nuclear forces. To satisfy the requirement, the Air Force planned to deploy an advanced Extremely High Frequency (EHF) satellite communications constellation. This constellation would provide a survivable, high capability communication system. Based on favorable results from a funded risk reduction study, the B-2 would be modified to integrate an EHF communication capability satisfying connectivity requirements.
Digital Engine Controller - The current analog engine controllers were high failure items, and without funding, ACC would be forced to ground aircraft beginning approximately FY08. Replacement of the engine controllers was decided on to improve the B-2's performance and increase supportability, reliability, and maintainability.Computers/Processors - With advances in computer technology and increased demands on the system, the B-2's computers were expected to need to be replaced with more advanced processors. Although reliable, maintaining the existing processors would become increasingly difficult and costly.
Signature Improvements - The B-2's signature met operational requirements against threats when it was deployed. As advanced threats proliferate, it was noted that it would be prudent to investigate advanced signature reduction concepts and determine if it was necessary to improve the B-2's low observable signature.
Weapon Systems - Tactical delivery tactics use patterns and techniques that minimize final flight path predictability, yet allow sufficient time for accurate weapons delivery. For conventional munitions. Bomb Rack Assembly (BRA) weapons delivery accuracies depend on delivery altitude. For a weapons pass made at 5,000 ft above ground level [AGL] or below, the hit criteria is less than or equal to 300 feet. For a weapons pass made above 5,000 feet AGL, the hit criteria is less than or equal to 500 feet. Similarly, Rotary Launcher Assembly (RLA) delivery of conventional or nuclear weapons (i.e. Mk 84, B-83, B-61) is altitude dependent. For a weapons pass made at 5,000 feet AGL or below, the hit criteria is less than or equal to 300 feet. For a weapons pass made above 5,000 ft AGL, the hit criteria is less than or equal to 500 feet. The hit criteria for a weapons pass made with GAM/JDAM munitions is less than or equal to 50 feet. As a result the Air Force engaged in a program to modify the fleet of B-2 stealth bombers to carry then new 500-pound satellite-guided GBU-30 Joint Direct Attack Munition (JDAM) bombs as soon as February 2003. The B-2 could carry 16 of the 2,000-pound satellite-guided bombs and as many as 80 of the 500-pound version.
In March 2002 it was reported that the Air Force had discovered cracks on the rear sections of 16 of the 21 B-2 stealth bombers. The cracks ranged in length from less than an inch to nine inches. They were all on titanium plates behind the jets' engine exhausts. The Air Force determined that the cracks did not pose an immediate danger to the B-2's, though maintenance crews were required to measure each of the cracks after every flight to see if they were growing.
The first of a series of planned upgrades to the B-2 Spirit Bomber entered flight test in FY03. This bundled package of capability included the upgraded, or "Smart" Bomb Rack Assembly, ability to drop the Mark 82 based 500 lb JDAM, ability to drop the Enhanced Guided Bomb Unit-28 (EGBU-28) bunker buster, and addition of improved voice and data communication via integration of a programmable UHF satellite communication terminal. Incorporation of this upgraded package into the fleet began in FY04.
Candidate Long Term Upgrades Beyond FY15
The basis for the useful life of the B-2 includes data from initial Developmental Test and Evaluation analysis. Data indicated the aircraft should be structurally sound to approximately 40,000 flight hours using existing mission profiles. Analysis further suggested that the rudder attachment points were the first structural failure item. The B-2 had not implemented an ASIP similar to the other bombers, which made it difficult to predict the economic service life and attrition rate. However, a notional projection, based on the B-52, predicted one aircraft would be lost each 10 years. This attrition rate, plus attrition due to service life, would erode the B-2 force below its requirement of 19 aircraft by 2027.
B-2 Radar Modernization Program (RMP)
The Air Force's B-2 RMP was designed to modify the current radar system to resolve potential conflicts in frequency band usage. To comply with federal requirements the frequency must be changed to a band where the DoD has been designated as the primary user. The modified radar system was being designed to support the B-2 stealth bomber and its combination of stealth, range, payload, and nearprecision weapons delivery capabilities.
As of a March 2007 report by the Government Accountability Office, all four of the B-2 RMPs designated critical technologies were considered mature and 100 percent of the design drawings, a measure of design stability, had been released. Production maturity metrics were to be formulated as part of a production readiness review prior to the April 2007 start of production. However, the first of two radar antenna software sets would not complete operational testing until 2008. Further, the program did not begin tracking the radar's operational reliability until early 2007. Program flight-testing delays were noted to be potentially leading to a delay in the planned start of production. Also, six operational B-2s were to receive development radar units prior to the completion of flight testing. These units were necessary to obtain reliability and maintainability data and for crew training, but building them early in development was a move to potentially added to the risk of future design changes.
All four B-2 RMP critical technologies were considered mature at the design review in May 2005. While the program entered development in August 2004 with two of these four critical technologies mature and two approaching maturity, the receiver/exciter for the electronic driver cards and aspects of the antenna designed to help keep the B-2's radar signature low, all four were considered mature by March 2007.
According to the GAO report the program did not use manufacturing process control data as the sole measure of production maturity because of the small number of production units. However, the program had identified one key process related to the assembly of the radar antenna array. Instead of using manufacturing process control data, the program planned to formulate other metrics to measure progress toward production. The program planned to use these other metrics as part of a production readiness review prior to the start of production in April 2007.
The program planned to enter production in April 2007 and procure four radars at a cost of $160.7 million. However, recent flight-testing delays had the potential to lead to a reconsideration of April 2007 as the start of production and it was not expected to be until the beginning of FY08 when radar flight-testing had progressed to the point that the first of two planned radar antenna software sets were fully tested and certified. Furthermore, the program did not plan to track the operational reliability of the radar until January 2007. An operational assessment of the radar was delayed from March 2006 to early 2007. This was an important schedule event leading up to production and its delay was said to clearly impact when information would be available leading up to the start of production according to the GAO. Producing units before testing was able to demonstrate the design was mature and worked in its intended environment was expected to increase the likelihood of future costly design changes.
The program planned to build six radar units during development to be used on B-2 aircraft to gather developmental reliability and maintainability data and provide for crew training and proficiency operations when the legacy radar frequency was no longer available. In 2006, the Air Force plan was for six of these radar units to be placed on B-2 aircraft for this purpose, but because some B-2s were needed for other operations and would not be available, only two operational aircraft would initially be fitted with the new radars, with the remaining four expected to be fitted later in 2007. The Air Force and prime contractor determined this would not affect training, but would mean less radar reliability and maintainability data would initially be collected for analysis.
In response to the GAO report the Air Force agreed that producing radar units before testing had been completed did increase the risk of future potentially costly design changes, but that the risk was low compared to the benefits gained by having operational production units in place to meet requirements.
In March 2008 the GAO again reported on the B-2 RMP, in early 2007, noting that the program experienced problems with the radar antenna. The GAO cited the aggressive development schedule, in which some important systems engineering and systems integration tasks were not completed. As a consequence, antenna performance deficiencies forced a delay in the development program, including flight test, in January 2007. These issues caused a 1 year delay in the start of production. Consequently, the Air Force reprogrammed FY07 production funds to other priorities. Flight testing resumed in June 2007 to verify the problems had been fixed. The program planned to enter production in August 2008.
Although the Air Force intended to enter production in FY08, important testing events, including the completion of development flight testing and operational testing, were not scheduled for completion until FY09. The GAO noted in its report that producing units before testing was able to demonstrate the design was mature and could work in its intended environment increased the risk of costly design changes in the future. The program office noted that it planned to mitigate concurrency between development and production by completing qualification tests, flight-testing for conventional combat capability, and an operational assessment prior to a production decision.
B-2 Advanced Extremely High Frequency Satellite Communication (EHF SATCOM) Capability
The Air Force B-2 EHF SATCOM was an improved satellite communication system designed to upgrade the existing avionics infrastructure, replace the ultra high frequency (UHF) system, and ensure continued secure, survivable communication capability while maintaining the B-2's low-observable signature. The program had three increments as of March 2008. Increment 1 included upgraded flight management computer processors. Increment 2 would add antennaes and radomes. Increment 3 would allow connectivity to the Global Information Grid. As of March 2008, Increment 1 was the only increment in system development.
In a March 2008 GAO report, all five of the B-2 EHF SATCOM critical technologies for Increment 1 were described as approaching maturity, but were not expected to be fully mature until after the planned design review. The program office considered the design to be stable since it used hardware that was already in use in another aircraft. However, the uncertainty with technology maturity was of concern to the GAO, who suggested that it could affect system integration activities and design stability. While Increments 2 and 3 were not yet in development, areas of potential concern already existed. According to the program office, Increment 2 would require physical changes, integration of large radomes and antenna, that presented additional risk to the low-observable nature of the aircraft. Further, Increment 3 requirements were not yet defined or funded.
While the B-2 EHF SATCOM program entered system development in February 2007 with all five of its critical technologies approaching maturity, the program office did not expect the technologies to be demonstrated in a realistic environment, and therefore fully mature, until after the design review. This increased the risk that the program could encounter further technology issues as it integrated those technologies into the B-2 aircraft. For example, the program was still developing the disk drive unit, a high-risk item that was essential to Increment 1 modernization efforts. If unable to mature this technology as expected, the program potentially had to face schedule delays and increased costs. The program did not have back-up technologies.
As of March 2008, the program had released nearly 63 percent of its drawings, a measure of design stability, but planned all to be released by the Critical Design Review planned for June 2008. A production readiness review was scheduled for January 2011, followed by a low-rate initial production decision in July 2011 and a full-rate production decision in April 2012.
Increments 1 and 2 of the B-2 EHF SATCOM program were estimated to cost nearly $1.9 billion. While Increments 2 and 3 were not yet in development, areas of potential concern already existed according to the GAO. The program office expected Increment 2 to represent a major modification to the system. Specifically, Increment 2 would require physical changes that present additional risk to the low-observable nature of the aircraft because of the integration of large radomes and antenna. Increment 2 planned to incorporate six additional technologies, two of which were very immature. The program began a component advance development phase in November 2007 to define requirements and begin preliminary design activities. System development for Increment 2 was expected to begin in November 2010. Fielding the completed EHF capability in time to meet operational needs was at the time at risk due to funding constraints and other program dependencies. For example, the Family of Advanced Beyond Line-of-Sight Terminals (FAB-T) was a supporting program that had to the potential to negatively affect B-2 EHF SATCOM development efforts, since it had already experienced significant delays. In addition to the risks identified for Increment 2, Increment 3 requirements were not yet defined or funded and its four critical technologies were immature.
In response to the GAO report, the the Air Force noted that it expected the risks associated with the disk drive unit to be fully mitigated when hardware testing was completed in May 2009. At that time it believed all critical technologies would be demonstrated to be low or moderate risk. System integration was expected to be demonstrated with lab testing complete by September 2009, flight testing beginning in November 2009, and completion of an operational assessment prior to the low-rate initial production decision in July 2011. The Air Force also noted that the existing FAB-T program plans supported the B-2 EHF SATCOM schedule.
Defensive Management System (DMS)
In response to significant enemy air defense-system upgrades, the US Air Force is angling to modernize their aircraft’s digital arsenal with improved sensors. Other upgrades include the Long Range Stand-Off weapon, long range nuclear cruise missiles, like the B-61 Mod 12, and the so-called defensive management system (DMS), to provide pilots with knowledge of the location of enemy anti-aircraft defense posts.
“With necessary upgrades, the B-2 can perform its mission regardless of location, return to base safely, and permit freedom of movement for follow-on forces, including other long range strike platforms,” Air Force Captain Michael Hertzog said. The DMS upgrade is “necessary” to maintain the B-2’s threat credibility, Hertzog added.
Rearming the B-2 with upgraded capabilities is crucial, as the next-generation Long-Range Strike Bomber (LRS-B) will not begin flight-tests until the mid-2020s, according to the Congressional Research Service. “Air Force and aerospace industry experts insist that with sufficient funding for sustainment and modernization over their expected lifetimes, all three of the existing bombers [the B-52, B-1, and B-2] can physically last and continue to remain credible weapons systems,” report author Jeremiah Gertler wrote. The Air Force has lengthened the operational life of B-2s until 2058, Gertler added.
A US Air Force pilot told Scout Warrior that the B-2 is the “smoothest” aircraft the pilot had ever flown. The stealthy airship was designed to fly at some 50,000 feet altitude to thwart enemy air defense systems for other aircraft assets to swoop in, Scout’s Kris Osborn said. The B-2 is capable of flying for 44 hours without refueling. The service currently maintains 16 combat-ready B-2s, according to the Congressional Research Service.
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