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The Northrop (later Northrop Grumman) B-2 Spirit, also known as the Stealth Bomber, is an American
heavy Heavy may refer to: Measures * Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight * Heavy, a characterization of objects with substantial weight * Heavy, ...
strategic bomber, featuring low-observable stealth technology designed to penetrate dense anti-aircraft defenses. A subsonic flying wing with a crew of two, the plane was designed by Northrop, later
Northrop Grumman Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military techn ...
, and produced from 1987 to 2000. The bomber can drop conventional and
thermonuclear weapon A thermonuclear weapon, fusion weapon or hydrogen bomb (H bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a low ...
s, such as up to eighty Mk 82
JDAM The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs", into all-weather precision-guided munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Po ...
GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
-guided bombs, or sixteen
B83 nuclear bomb The B83 is a variable-yield thermonuclear gravity bomb developed by the United States in the late 1970s that entered service in 1983. With a maximum yield of , it has been the most powerful nuclear weapon in the United States nuclear arsenal ...
s. The B-2 is the only acknowledged aircraft that can carry large
air-to-surface An air-to-surface missile (ASM) or air-to-ground missile (AGM) is a missile designed to be launched from military aircraft at targets on land or sea. There are also unpowered guided glide bombs not considered missiles. The two most common prop ...
standoff weapons in a stealth configuration. Development began under the Advanced Technology Bomber (ATB) project during the Carter administration, which cancelled the Mach 2-capable B-1A bomber in part because the ATB showed such promise. But development difficulties delayed progress and drove costs up. Ultimately, the program produced 21 B-2s at an average cost of $2.13 billion (in 1997 dollars), including development, engineering, testing, production, and procurement. Just building each aircraft cost an average of US$737 million,"B-2 Bomber: Cost and Operational Issues Letter Report, GAO/NSIAD-97-181."
''United States General Accounting Office'' (GAO), 14 August 1997. Retrieved 13 December 2018.
while total
procurement Procurement is the method of discovering and agreeing to terms and purchasing goods, services, or other works from an external source, often with the use of a tendering or competitive bidding process. When a government agency buys goods or serv ...
costs (including production, spare parts, equipment,
retrofitting Retrofitting is the addition of new technology or features to older systems. Retrofits can happen for a number of reasons, for example with big capital expenditures like naval vessels, military equipment or manufacturing plants, businesses or go ...
, and software support) averaged $929 million per plane. The project's considerable capital and
operating cost Operating costs or operational costs, are the expenses which are related to the operation of a business, or to the operation of a device, component, piece of equipment or facility. They are the cost of resources used by an organization just to main ...
s made it controversial in the
U.S. Congress The United States Congress is the legislature of the federal government of the United States. It is bicameral, composed of a lower body, the House of Representatives, and an upper body, the Senate. It meets in the U.S. Capitol in Washin ...
even before the winding-down of the Cold War dramatically reduced the need for a stealthy aircraft designed to strike deep in Soviet territory. Consequently, in the late 1980s and 1990s lawmakers shrank the planned purchase of 132 bombers to just 21. As of 2022, twenty B-2s are in service with the
United States Air Force The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...
. (One was destroyed in a 2008
crash Crash or CRASH may refer to: Common meanings * Collision, an impact between two or more objects * Crash (computing), a condition where a program ceases to respond * Cardiac arrest, a medical condition in which the heart stops beating * Couch su ...
.) The Air Force plans to operate them until 2032, when the
Northrop Grumman B-21 Raider The Northrop Grumman B-21 Raider is an American strategic bomber under development for the United States Air Force (USAF) by Northrop Grumman. As part of the Long Range Strike Bomber (LRS-B) program, it is to be a long-range, stealth intercon ...
is to replace them. The B-2 can perform attack missions up to ; it has an unrefueled range of more than and can fly more than with one midair refueling. It entered service in 1997 as the second aircraft designed with advanced stealth technology, after the
Lockheed F-117 Nighthawk The Lockheed F-117 Nighthawk is a retired American single-seat, twin-engine stealth attack aircraft developed by Lockheed's secretive Skunk Works division and operated by the United States Air Force (USAF). It was the first operational aircr ...
attack aircraft. Primarily designed as a nuclear bomber, the B-2 was first used in combat to drop conventional, non-nuclear ordnance in the
Kosovo War The Kosovo War was an armed conflict in Kosovo that started 28 February 1998 and lasted until 11 June 1999. It was fought by the forces of the Federal Republic of Yugoslavia (i.e. Serbia and Montenegro), which controlled Kosovo before the wa ...
in 1999. It was later used in
Iraq Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to the north, Iran to the east, the Persian Gulf and K ...
,
Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
, and
Libya Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to the east, Suda ...
.


Development


Origins

By the mid-1970s, military aircraft designers had learned of a new method to avoid missiles and interceptors, known today as " stealth". The concept was to build an aircraft with an airframe that deflected or absorbed
radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...
signals so that little was reflected back to the radar unit. An aircraft having radar stealth characteristics would be able to fly nearly undetected and could be attacked only by weapons and systems not relying on radar. Although other detection measures existed, such as human observation, infrared scanners, acoustic locators, their relatively short detection range or poorly-developed technology allowed most aircraft to fly undetected, or at least untracked, especially at night. In 1974,
DARPA The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Ad ...
requested information from U.S. aviation firms about the largest radar cross-section of an aircraft that would remain effectively invisible to radars. Initially, Northrop and
McDonnell Douglas McDonnell Douglas was a major American aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it pro ...
were selected for further development. Lockheed had experience in this field due to developing the
Lockheed A-12 The Lockheed A-12 is a high-altitude, Mach 3+ reconnaissance aircraft built for the United States Central Intelligence Agency (CIA) by Lockheed's Skunk Works, based on the designs of Clarence "Kelly" Johnson. The aircraft was designat ...
and SR-71, which included a number of stealthy features, notably its canted vertical stabilizers, the use of composite materials in key locations, and the overall surface finish in radar-absorbing paint. A key improvement was the introduction of computer models used to predict the radar reflections from flat surfaces where collected data drove the design of a "faceted" aircraft. Development of the first such designs started in 1975 with "the Hopeless Diamond", a model Lockheed built to test the concept. Plans were well advanced by the summer of 1975, when DARPA started the Experimental Survivability Testbed (XST) project. Northrop and Lockheed were awarded contracts in the first round of testing. Lockheed received the sole award for the second test round in April 1976 leading to the Have Blue program and eventually the
F-117 The Lockheed F-117 Nighthawk is a retired American single-seat, twin-engine stealth attack aircraft developed by Lockheed's secretive Skunk Works division and operated by the United States Air Force (USAF). It was the first operational aircr ...
stealth attack aircraft. Northrop also had a classified technology demonstration aircraft, the Tacit Blue in development in 1979 at
Area 51 Area 51 is the common name of a highly classified United States Air Force (USAF) facility within the Nevada Test and Training Range. A remote detachment administered by Edwards Air Force Base, the facility is officially called Homey Airport ...
. It developed stealth technology, LO (low observables),
fly-by-wire Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control ...
, curved surfaces, composite materials, electronic intelligence (ELINT), and Battlefield Surveillance Aircraft Experimental (BSAX). "The stealth technology developed from the program was later incorporated into other operational aircraft designs, including the B-2 stealth bomber".


ATB program

By 1976, these programs had progressed to a position in which a long-range strategic stealth bomber appeared viable. President Carter became aware of these developments during 1977, and it appears to have been one of the major reasons the B-1 was canceled. Further studies were ordered in early 1978, by which point the Have Blue platform had flown and proven the concepts. During the 1980 presidential election campaign in 1979, Ronald Reagan repeatedly stated that Carter was weak on defense, and used the B-1 as a prime example. In response, on 22 August 1980 the Carter administration publicly disclosed that the
United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...
was working to develop stealth aircraft, including a bomber.Goodall 1992, The Advanced Technology Bomber (ATB) program began in 1979. Full development of the
black project A black project is a highly classified, top-secret military or defense project that is not publicly acknowledged by government, military personnel, or contractors. Examples of United States military aircraft developed as black projects include the ...
followed, and was funded under the code name "
Aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...
". After the evaluations of the companies' proposals, the ATB competition was narrowed to the Northrop/
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and p ...
and Lockheed/ Rockwell teams with each receiving a study contract for further work. Both teams used flying wing designs. The Northrop proposal was code named "Senior Ice" and the Lockheed proposal code named " Senior Peg". Northrop had prior experience developing the YB-35 and
YB-49 The Northrop YB-49 was an American prototype jet-powered heavy bomber developed by Northrop Corporation shortly after World War II for service with the United States Air Force. The YB-49 featured a flying wing design and was a turbojet-powered d ...
flying wing aircraft. The Northrop design was larger while the Lockheed design included a small tail. In 1979, designer Hal Markarian produced a sketch of the aircraft, that bore considerable similarities to the final design. The USAF originally planned to procure 165 of the ATB bomber. The Northrop team's ATB design was selected over the Lockheed/Rockwell design on 20 October 1981. The Northrop design received the designation B-2 and the name "Spirit". The bomber's design was changed in the mid-1980s when the mission profile was changed from high-altitude to low-altitude, terrain-following. The redesign delayed the B-2's first flight by two years and added about US$1 billion to the program's cost. An estimated US$23 billion was secretly spent for research and development on the B-2 by 1989.
MIT The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the m ...
engineers and scientists helped assess the mission effectiveness of the aircraft under a five-year classified contract during the 1980s.


Secrecy and espionage

During its design and development, the Northrop B-2 program was a
black project A black project is a highly classified, top-secret military or defense project that is not publicly acknowledged by government, military personnel, or contractors. Examples of United States military aircraft developed as black projects include the ...
; all program personnel needed a secret clearance. Still, it was less closely held than the Lockheed F-117 program; more people in the federal government knew about the B-2 and more information about the project was available. Both during development and in service, considerable effort has been devoted to maintaining the security of the B-2's design and technologies. Staff working on the B-2 in most, if not all, capacities need a level of special-access clearance, and undergo extensive background checks carried out by a special branch of the USAF. A former Ford automobile assembly plant in Pico Rivera, California, was acquired and heavily rebuilt; the plant's employees were sworn to secrecy. To avoid suspicion, components were typically purchased through
front companies A front organization is any entity set up by and controlled by another organization, such as intelligence agencies, organized crime groups, terrorist organizations, secret societies, banned organizations, religious or political groups, advocacy gro ...
, military officials would visit out of uniform, and staff members were routinely subjected to
polygraph A polygraph, often incorrectly referred to as a lie detector test, is a device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person is asked ...
examinations. Nearly all information on the program was kept from the Government Accountability Office (GAO) and members of Congress until the mid-1980s. Northrop (now Northrop Grumman) was the B-2's prime contractor; major subcontractors included
Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and p ...
,
Hughes Aircraft The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of Hughes Tool Company. The company was known for producing, among other pro ...
(now
Raytheon Raytheon Technologies Corporation is an American multinational aerospace and defense conglomerate headquartered in Arlington, Virginia. It is one of the largest aerospace and defense manufacturers in the world by revenue and market capitali ...
), GE, and
Vought Aircraft Vought was the name of several related American aerospace firms. These have included, in the past, Lewis and Vought Corporation, Chance Vought, Vought-Sikorsky, LTV Aerospace (part of Ling-Temco-Vought), Vought Aircraft Companies, and Vought Ai ...
. In 1984, Northrop employee Thomas Cavanaugh was arrested for attempting to sell
classified information Classified information is material that a government body deems to be sensitive information that must be protected. Access is restricted by law or regulation to particular groups of people with the necessary security clearance and need to kn ...
from the Pico Rivera factory to the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
. Cavanaugh was eventually sentenced to life in prison and released on parole in 2001. The B-2 was first publicly displayed on 22 November 1988 at
United States Air Force Plant 42 United States Air Force Plant 42 is a classified aircraft manufacturing plant owned by the United States Air Force in the Antelope Valley, about from downtown Los Angeles. It is also used by the National Aeronautics and Space Administration (N ...
in Palmdale, California, where it was assembled. This viewing was heavily restricted, and guests were not allowed to see the rear of the B-2. However, ''
Aviation Week ''Aviation Week & Space Technology'', often abbreviated ''Aviation Week'' or ''AW&ST'', is the flagship magazine of the Aviation Week Network. The weekly magazine is available in print and online, reporting on the aerospace, defense and aviatio ...
'' editors found that there were no airspace restrictions above the presentation area and took aerial photographs of the aircraft's then-secret rear section with suppressed engine exhausts. The B-2's (s/n 82-1066 / AV-1) first public flight was on 17 July 1989 from Palmdale to Edwards AFB.Pace 1999, pp. 29–36. In October 2005, Noshir Gowadia, a design engineer who worked on the B-2's propulsion system, was arrested for selling classified information to China. Gowadia was convicted and sentenced to 32 years in prison.


Program costs and procurement

A procurement of 132 aircraft was planned in the mid-1980s, but was later reduced to 75. By the early 1990s the Soviet Union dissolved, effectively eliminating the Spirit's primary Cold War mission. Under budgetary pressures and Congressional opposition, in his 1992
State of the Union Address The State of the Union Address (sometimes abbreviated to SOTU) is an annual message delivered by the president of the United States to a joint session of the United States Congress near the beginning of each calendar year on the current conditi ...
, President George H. W. Bush announced B-2 production would be limited to 20 aircraft. In 1996, however, the Clinton administration, though originally committed to ending production of the bombers at 20 aircraft, authorized the conversion of a 21st bomber, a prototype test model, to Block 30 fully operational status at a cost of nearly $500 million. In 1995, Northrop made a proposal to the USAF to build 20 additional aircraft with a flyaway cost of $566 million each.Eden 2004, pp. 350–353. The program was the subject of public controversy for its cost to American taxpayers. In 1996, the
General Accounting Office The U.S. Government Accountability Office (GAO) is a legislative branch government agency that provides auditing, evaluative, and investigative services for the United States Congress. It is the supreme audit institution of the federal gover ...
(GAO) disclosed that the USAF's B-2 bombers "will be, by far, the most costly bombers to operate on a per aircraft basis", costing over three times as much as the
B-1B The Rockwell B-1 Lancer is a supersonic variable-sweep wing, heavy bomber used by the United States Air Force. It is commonly called the "Bone" (from "B-One"). It is one of three strategic bombers serving in the U.S. Air Force fleet along wit ...
(US$9.6 million annually) and over four times as much as the B-52H (US$6.8 million annually). In September 1997, each hour of B-2 flight necessitated 119 hours of maintenance in turn. Comparable maintenance needs for the B-52 and the B-1B are 53 and 60 hours respectively for each hour of flight. A key reason for this cost is the provision of air-conditioned hangars large enough for the bomber's wingspan, which are needed to maintain the aircraft's stealth properties, particularly its "low-observable" stealth skins. Maintenance costs are about $3.4 million a month for each aircraft. An August 1995 GAO report disclosed that the B-2 had trouble operating in heavy rain, as this rain could damage the aircraft's stealth coating, causing procurement delays until an adequate protective coating could be found. In addition, the B-2's terrain-following/terrain-avoidance radar had difficulty distinguishing rain from other obstacles, rendering the subsystem inoperable during rain. However a subsequent report in October 1996 noted that the USAF had made some progress in resolving the issues with the radar via software fixes and hoped to have these fixes undergoing tests by the spring of 1997. The total "military construction" cost related to the program was projected to be US$553.6 million in 1997 dollars. The cost to procure each B-2 was US$737 million in 1997 dollars (equivalent to US$ million in 2021), based only on a fleet cost of US$15.48 billion. The procurement cost per aircraft as detailed in GAO reports, which include spare parts and software support, was $929 million per aircraft in 1997 dollars. The total program cost projected through 2004 was US$44.75 billion in 1997 dollars (equivalent to US$ billion in 2021). This includes development, procurement, facilities, construction, and spare parts. The total program cost averaged US$2.13 billion per aircraft. The B-2 may cost up to $135,000 per flight hour to operate in 2010, which is about twice that of the B-52 and B-1.Axe, David
"Why Can't the Air Force Build an Affordable Plane?"
''The Atlantic'', 26 March 2012. Retrieved 30 June 2012.


Opposition

In its consideration of the fiscal year 1990 defense budget, the House Armed Services Committee trimmed $800 million from the B-2 research and development budget, while at the same time staving off a motion to end the project. Opposition in committee and in Congress was mostly broad and bipartisan, with Congressmen Ron Dellums (D-CA),
John Kasich John Richard Kasich Jr. ( ; born May 13, 1952) is an American politician, author, and television news host who served in the U.S. House of Representatives from 1983 to 2001 and as the 69th governor of Ohio from 2011 to 2019. A Republican, Kasic ...
(R-OH), and John G. Rowland (R-CT) authorizing the motion to end the project—as well as others in the Senate, including Jim Exon (D-NE) and John McCain (R-AZ) also opposing the project.Schmitt, Eric
"Key Senate Backer of Stealth Bomber Sees It in Jeopardy."
''The New York Times'', 14 September 1991. Retrieved 23 July 2009.
Dellums and Kasich, in particular, worked together from 1989 through the early 1990s to limit production to 21 aircraft, and were ultimately successful. The escalating cost of the B-2 program and evidence of flaws in the aircraft's ability to elude detection by radar were among factors that drove opposition to continue the program. At the peak production period specified in 1989, the schedule called for spending US$7 billion to $8 billion per year in 1989 dollars, something Committee Chair
Les Aspin Leslie Aspin Jr. (July 21, 1938 – May 21, 1995) was an American Democratic Party politician who served as the U.S. representative for Wisconsin's 1st congressional district from 1971 to 1993 and as the 18th United States Secretary of Defe ...
(D-WI) said "won't fly financially". In 1990, the Department of Defense accused Northrop of using faulty components in the
flight control system A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight. Aircraft ...
; it was also found that redesign work was required to reduce the risk of damage to engine fan blades by bird ingestion. In time, a number of prominent members of Congress began to oppose the program's expansion, including later Democratic presidential nominee
John Kerry John Forbes Kerry (born December 11, 1943) is an American attorney, politician and diplomat who currently serves as the first United States special presidential envoy for climate. A member of the Forbes family and the Democratic Party, he ...
, who cast votes against the B-2 in 1989, 1991 and 1992 while a U.S. Senator, representing
Massachusetts Massachusetts (Massachusett: ''Muhsachuweesut Massachusett_writing_systems.html" ;"title="nowiki/> məhswatʃəwiːsət.html" ;"title="Massachusett writing systems">məhswatʃəwiːsət">Massachusett writing systems">məhswatʃəwiːsət'' En ...
. By 1992, Republican President George H. W. Bush called for the cancellation of the B-2 and promised to cut military spending by 30% in the wake of the collapse of the Soviet Union. In October 1995, former Chief of Staff of the United States Air Force, General Mike Ryan, and former Chairman of the Joint Chiefs of Staff, General
John Shalikashvili John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second ...
, strongly recommended against Congressional action to fund the purchase of any additional B-2s, arguing that to do so would require unacceptable cuts in existing conventional and nuclear-capable aircraft, and that the military had greater priorities in spending a limited budget. Some B-2 advocates argued that procuring twenty additional aircraft would save money because B-2s would be able to deeply penetrate anti-aircraft defenses and use low-cost, short-range attack weapons rather than expensive standoff weapons. However, in 1995, the
Congressional Budget Office The Congressional Budget Office (CBO) is a List of United States federal agencies, federal agency within the United States Congress, legislative branch of the United States government that provides budget and economic information to Congress. Ins ...
(CBO), and its Director of National Security Analysis, found that additional B-2s would reduce the cost of expended munitions by less than US$2 billion in 1995 dollars during the first two weeks of a conflict, in which the USAF predicted bombers would make their greatest contribution; a small fraction of the US$26.8 billion (in 1995 dollars) life cycle cost that the CBO projected for an additional 20 B-2s. In 1997, as
Ranking Member In United States politics, a ranking member is the most senior member of a congressional or state legislative committee from the minority party. On many committees the ranking minority member, along with the Chair, serve as '' ex officio'' member ...
of the
House Armed Services Committee The U.S. House Committee on Armed Services, commonly known as the House Armed Services Committee or HASC, is a standing committee of the United States House of Representatives. It is responsible for funding and oversight of the Department of De ...
and National Security Committee, Congressman Ron Dellums (D-CA), a long-time opponent of the bomber, cited five independent studies and offered an amendment to that year's defense authorization bill to cap production of the bombers to the existing 21 aircraft; the amendment was narrowly defeated."Debate on Dellums Amendment to 1998 Defense Authorization Act."
''fas.org'', 23 June 1997.
Nonetheless, Congress did not approve funding for additional B-2s.


Further developments

A number of upgrade packages have been applied to the B-2. In July 2008, the B-2's onboard computing architecture was extensively redesigned; it now incorporates a new integrated processing unit (IPU) that communicates with systems throughout the aircraft via a newly installed
fiber optic An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means t ...
network; a new version of the operational flight program software was also developed, with legacy code converted from the
JOVIAL JOVIAL is a high-level programming language based on ALGOL 58, specialized for developing embedded systems (specialized computer systems designed to perform one or a few dedicated functions, usually embedded as part of a larger, more complete dev ...
programming language to standard C. Updates were also made to the weapon control systems to enable strikes upon moving targets, such as ground vehicles. On 29 December 2008, USAF officials awarded a US$468 million contract to Northrop Grumman to modernize the B-2 fleet's radars. Changing the radar's frequency was required as the
United States Department of Commerce The United States Department of Commerce is an executive department of the U.S. federal government concerned with creating the conditions for economic growth and opportunity. Among its tasks are gathering economic and demographic data for bus ...
had sold that radio spectrum to another operator. In July 2009, it was reported that the B-2 had successfully passed a major USAF audit. In 2010, it was made public that the
Air Force Research Laboratory The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...
had developed a new material to be used on the part of the wing trailing edge subject to engine exhaust, replacing existing material that quickly degraded. In July 2010, political analyst Rebecca Grant speculated that when the B-2 becomes unable to reliably penetrate enemy defenses, the
Lockheed Martin F-35 Lightning II The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather Stealth aircraft, stealth multirole combat aircraft that is intended to perform both Air superiority fighter, air superiority and attack ...
may take on its strike/
interdiction Interdiction is a military term for the act of delaying, disrupting, or destroying enemy forces or supplies en route to the battle area. A distinction is often made between strategic and tactical interdiction. The former refers to operations whose ...
mission, carrying
B61 nuclear bomb The B61 nuclear bomb is the primary thermonuclear gravity bomb in the United States Enduring Stockpile following the end of the Cold War. It is a low to intermediate-yield strategic and tactical nuclear weapon featuring a two-stage radiation im ...
s as a tactical bomber. However, in March 2012, the Pentagon announced that a $2 billion, 10-year-long modernization of the B-2 fleet was to begin. The main area of improvement would be replacement of outdated avionics and equipment.Kelley, Michael
"The Air Force Announced It's Upgrading The One Plane It Needs To Bomb Iran."
''Business Insider'', 28 March 2012.
Continued modernization efforts likely have continued in secret, as alluded to by a B-2 commander from Whiteman AFB in April 2021, possibly indicating offensive weapons capability against threatening air defenses and aircraft. He stated: It was reported in 2011 that the Pentagon was evaluating an unmanned stealth bomber, characterized as a "mini-B-2", as a potential replacement in the near future. In 2012, USAF Chief of Staff General Norton Schwartz stated the B-2's 1980s-era stealth technologies would make it less survivable in future contested airspaces, so the USAF is to proceed with the
Next-Generation Bomber The Next-Generation Bomber (NGB; unofficially called 2018 Bomber) was a program to develop a new medium bomber for the United States Air Force. The NGB was initially projected to enter service around 2018 as a stealthy, subsonic, medium-range, m ...
despite overall budget cuts. In 2012 projections, it was estimated that the Next-Generation Bomber would have an overall cost of $55 billion. In 2013, the USAF contracted for the Defensive Management System Modernization program to replace the antenna system and other electronics to increase the B-2's frequency awareness. The Common Very Low Frequency Receiver upgrade will allow the B-2s to use the same
very low frequency Very low frequency or VLF is the ITU designation for radio frequencies (RF) in the range of 3–30  kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave a ...
transmissions as the ''Ohio''-class submarines so as to continue in the nuclear mission until the
Mobile User Objective System The Mobile User Objective System (MUOS) is a United States Space Force narrowband military communications satellite system that supports a worldwide, multi-service population of users in the ultra high frequency (UHF) band. The system provides ...
is fielded. In 2014, the USAF outlined a series of upgrades including nuclear warfighting, a new integrated processing unit, the ability to carry cruise missiles, and threat warning improvements. In 1998, a Congressional panel advised the USAF to refocus resources away from continued B-2 production and instead begin development of a new bomber, either a new build or a variant of the B-2. In its 1999 bomber roadmap the USAF eschewed the panel's recommendations, believing its current bomber fleet could be maintained until the 2030s. The service believed that development could begin in 2013, in time to replace aging B-2s, B-1s and B-52s around 2037. Although the USAF previously planned to operate the B-2 to 2058, the FY 2019 budget moved up its retirement to "no later than 2032". It also moved retirement of the B-1 to 2036 while extending the B-52's service life into the 2050s, due to the latter's lower maintenance costs, versatile conventional payload, and ability to carry nuclear cruise missiles (which the B-1 is treaty-prohibited from doing). The decision to retire the B-2 early was made because the small fleet of 20 is considered too expensive per plane to retain, with its position as a stealth bomber being taken over with the introduction of the
B-21 Raider The Northrop Grumman B-21 Raider is an American strategic bomber under development for the United States Air Force (USAF) by Northrop Grumman. As part of the Long Range Strike Bomber (LRS-B) program, it is to be a long-range, stealth interc ...
starting in the mid-2020s.


Design


Overview

The B-2 Spirit was developed to take over the USAF's vital penetration missions, able to travel deep into enemy territory to deploy ordnance which could include
nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
s.Croddy and Wirtz 2005, pp. 341–342. The B-2 is a flying wing aircraft, meaning that it has no fuselage or tail. It has significant advantages over previous bombers due to its blend of low-observable technologies with high aerodynamic efficiency and large payload. Low observability provides a greater freedom of action at high altitudes, thus increasing both range and field of view for onboard sensors. The USAF reports its range as approximately . At cruising altitude, the B-2 refuels every six hours, taking on up to of fuel at a time. The development and construction of the B-2 required pioneering use of computer-aided design and
manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to ...
technologies, due to its complex flight characteristics and design requirements to maintain very low visibility to multiple means of detection. The B-2 bears a resemblance to earlier Northrop aircraft; the YB-35 and
YB-49 The Northrop YB-49 was an American prototype jet-powered heavy bomber developed by Northrop Corporation shortly after World War II for service with the United States Air Force. The YB-49 featured a flying wing design and was a turbojet-powered d ...
were both flying wing bombers that had been canceled in development in the early 1950s, allegedly for political reasons. The resemblance goes as far as B-2 and YB-49 having the same wingspan. The YB-49 also had a small radar cross-section. Approximately 80 pilots fly the B-2. Each aircraft has a crew of two, a pilot in the left seat and mission commander in the right, and has provisions for a third crew member if needed. For comparison, the B-1B has a crew of four and the B-52 has a crew of five. The B-2 is highly automated, and one crew member can sleep in a
camp bed A camp bed is a narrow, light-weight bed, often made of sturdy cloth stretched over a folding frame. The term camp bed is common in the United Kingdom, but in North America they are often referred to as cots. Camp beds are used by the military in ...
, use a toilet, or prepare a hot meal while the other monitors the aircraft, unlike most two-seat aircraft. Extensive
sleep cycle The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sle ...
and fatigue research was conducted to improve crew performance on long sorties. Advanced training is conducted at the
USAF Weapons School The USAF Weapons School is a unit of the United States Air Force and United States Space Force, assigned to the 57th Wing and Space Delta 1. It is located at Nellis AFB, Nevada. Mission The mission of the USAF Weapons School is to teach gradu ...
.


Armaments and equipment

The B-2, in the envisaged Cold War scenario, was to perform deep-penetrating nuclear strike missions, making use of its stealthy capabilities to avoid detection and interception throughout missions. There are two internal bomb bays in which munitions are stored either on a rotary launcher or two bomb-racks; the carriage of the weapons loadouts internally results in less radar visibility than external mounting of munitions. The B-2 is capable of carrying of ordnance. Nuclear ordnance includes the B61 and
B83 nuclear bomb The B83 is a variable-yield thermonuclear gravity bomb developed by the United States in the late 1970s that entered service in 1983. With a maximum yield of , it has been the most powerful nuclear weapon in the United States nuclear arsenal ...
s; the
AGM-129 ACM The AGM-129 ACM (Advanced Cruise Missile) was a low-observable, subsonic, turbofan-powered, air-launched cruise missile originally designed and built by General Dynamics and eventually acquired by Raytheon Missile Systems. Prior to its withdraw ...
cruise missile was also intended for use on the B-2 platform. It was decided, in light of the dissolution of the Soviet Union, to equip the B-2 for conventional precision attacks as well as for the strategic role of nuclear-strike. The B-2 features a sophisticated GPS-Aided Targeting System (GATS) that uses the aircraft's APQ-181
synthetic aperture radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide fine ...
to map out targets prior to deployment of
GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
-aided bombs (
GAMs Gams is a municipality in the ''Wahlkreis'' (constituency) of Werdenberg in the canton of St. Gallen in Switzerland. History Gams is first mentioned in 835 as ''Campesias''. In 1210 it was mentioned as ''Chames'', in 1236 as ''Gamps''. Unt ...
), later superseded by the Joint Direct Attack Munition (JDAM). In the B-2's original configuration, up to 16 GAMs or JDAMs could be deployed; an upgrade program in 2004 raised the maximum carriable capacity to 80 JDAMs. The B-2 has various conventional weapons in its arsenal, able to equip Mark 82 and
Mark 84 bomb The Mark 84 or BLU-117 is an American general-purpose bomb. It is the largest of the Mark 80 series of weapons. Entering service during the Vietnam War, it became a commonly used US heavy unguided bomb (due to the amount of high-explosive conten ...
s, CBU-87 Combined Effects Munitions, GATOR mines, and the CBU-97 Sensor Fuzed Weapon. In July 2009, Northrop Grumman reported the B-2 was compatible with the equipment necessary to deploy the
Massive Ordnance Penetrator The GBU-57A/B Massive Ordnance Penetrator (MOP) is a precision-guided, " bunker buster" bomb used by the United States Air Force. This is substantially larger than the deepest-penetrating bunker busters previously available, the GBU-28 and ...
(MOP), which is intended to attack reinforced
bunker A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. T ...
s; up to two MOPs could be equipped in the B-2's bomb bays with one per bay, the B-2 is the only platform compatible with the MOP as of 2012. As of 2011, the AGM-158 JASSM cruise missile is an upcoming standoff munition to be deployed on the B-2 and other platforms. This is to be followed by the Long Range Standoff Weapon which may give the B-2 a standoff nuclear capability for the first time.


Avionics and systems

To make the B-2 more effective than previous bombers, many advanced and modern avionics systems were integrated into its design; these have been modified and improved following a switch to conventional warfare missions. One system is the low probability of intercept AN/APQ-181 multi-mode radar, a fully digital navigation system that is integrated with
terrain-following radar Terrain-following radar (TFR) is a military aerospace technology that allows a very-low-flying aircraft to automatically maintain a relatively constant altitude above ground level and therefore make detection by enemy radar more difficult. It is ...
and
Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
(GPS) guidance, NAS-26 astro-inertial navigation system (first such system tested on the Northrop
SM-62 Snark The Northrop SM-62 Snark is an early-model intercontinental range ground-launched cruise missile that could carry a W39 thermonuclear warhead. The Snark was deployed by the United States Air Force's Strategic Air Command from 1958 through 1961 ...
cruise missile) and a Defensive Management System (DMS) to inform the flight crew of possible threats. The onboard DMS is capable of automatically assessing the detection capabilities of identified threats and indicated targets. The DMS will be upgraded by 2021 to detect radar emissions from air defenses to allow changes to the auto-router's mission planning information while in-flight so it can receive new data quickly to plan a route that minimizes exposure to dangers.Air Force Upgrades B-2 Stealth Bomber as Modern Air Defenses Advance
– Military.com, 24 April 2015
For safety and fault-detection purposes, an on-board test system is linked with the majority of avionics on the B-2 to continuously monitor the performance and status of thousands of components and consumables; it also provides post-mission servicing instructions for ground crews. In 2008, many of the 136 standalone distributed computers on board the B-2, including the primary flight management computer, were being replaced by a single integrated system. The avionics are controlled by 13 EMP-resistant
MIL-STD-1750A MIL-STD-1750A or 1750A is the formal definition of a 16-bit computer instruction set architecture (ISA), including both required and optional components, as described by the military standard document MIL-STD-1750A (1980). Since August 1996, it h ...
computers, which are interconnected through 26
MIL-STD-1553 MIL-STD-1553 is a military standard published by the United States Department of Defense that defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed as an avionic data bus for use with ...
B-
busses A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
; other system elements are connected via
optical fiber An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass ( silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a mea ...
. In addition to periodic software upgrades and the introduction of new radar-absorbent materials across the fleet, the B-2 has had several major upgrades to its avionics and combat systems. For battlefield communications, both
Link-16 Link 16 is a military tactical data link network used by NATO and nations allowed by the MIDS International Program Office (IPO). Its specification is part of the family of Tactical Data Links. With Link 16, military aircraft as well as ships ...
and a high frequency satellite link have been installed, compatibility with various new munitions has been undertaken, and the AN/APQ-181 radar's operational frequency was shifted to avoid interference with other operators' equipment. The arrays of the upgraded radar features were entirely replaced to make the AN/APQ-181 into an active electronically scanned array (AESA) radar. Due to the B-2's composite structure, it is required to stay away from
thunderstorms A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are somet ...
, to avoid static discharge and
lightning strike A lightning strike or lightning bolt is an electric discharge between the atmosphere and the ground. Most originate in a cumulonimbus cloud and terminate on the ground, called cloud-to-ground (CG) lightning. A less common type of strike, ground- ...
s.


Flight controls

To address the inherent flight instability of a flying wing aircraft, the B-2 uses a complex quadruplex computer-controlled
fly-by-wire Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control ...
flight control system that can automatically manipulate flight surfaces and settings without direct pilot inputs to maintain aircraft stability. The flight computer receives information on external conditions such as the aircraft's current air speed and angle of attack via pitot-static sensing plates, as opposed to traditional
pitot tube A pitot ( ) tube (pitot probe) measures fluid flow velocity. It was invented by a French engineer, Henri Pitot, in the early 18th century, and was modified to its modern form in the mid-19th century by a French scientist, Henry Darcy. It ...
s which would impair the aircraft's stealth capabilities. The flight actuation system incorporates both hydraulic and electrical servoactuated components, and it was designed with a high level of redundancy and fault-diagnostic capabilities. Northrop had investigated several means of applying directional control that would infringe on the aircraft's radar profile as little as possible, eventually settling on a combination of split brake-rudders and differential thrust. Engine thrust became a key element of the B-2's aerodynamic design process early on; thrust not only affects drag and lift but pitching and rolling motions as well. Four pairs of control surfaces are located along the wing's trailing edge; while most surfaces are used throughout the aircraft's flight envelope, the inner elevons are normally only in use at slow speeds, such as landing. To avoid potential contact damage during takeoff and to provide a nose-down pitching attitude, all of the elevons remain drooped during takeoff until a high enough airspeed has been attained.


Stealth

The B-2's low-observable, or " stealth", characteristics enable the undetected penetration of sophisticated anti-aircraft defenses and to attack even heavily defended targets. This stealth comes from a combination of reduced acoustic,
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
,
visual The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (th ...
and
radar signature Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...
s ( multi-spectral camouflage) to evade the various detection systems that could be used to detect and be used to direct attacks against an aircraft. The B-2's stealth enables the reduction of supporting aircraft that are required to provide air cover, Suppression of Enemy Air Defenses and electronic countermeasures, making the bomber a " force multiplier". , there have been no instances of a missile being launched at a B-2. To reduce optical visibility during daylight flights, the B-2 is painted in an anti-reflective paint. The undersides are dark because it flies at high altitudes (), and at that altitude a dark grey painting blends well into the sky. It is speculated to have an upward-facing
light sensor Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by ...
which alerts the pilot to increase or reduce altitude to match the changing illuminance of the sky. The original design had tanks for a
contrail Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails ar ...
-inhibiting chemical, but this was replaced in production aircraft by a contrail sensor that alerts the crew when they should change altitude. The B-2 is vulnerable to visual interception at ranges of or less. The B-2 is stored in a $5 million specialised air-conditioned hangar to maintain its stealth coating. Every seven years, this coating is carefully removed by being washed off with crystallised wheat starch so that the B-2's surfaces can be inspected for any dents or scratches.


Radar

Reportedly, the B-2 has a radar cross-section (RCS) of about . The bomber does not always fly stealthily; when nearing air defenses pilots "stealth up" the B-2, a maneuver whose details are secret. The aircraft is stealthy, except briefly when the bomb bay opens. The B-2's clean, low-drag flying wing configuration not only provides exceptional range but is also beneficial to reducing its radar profile. The flying wing design most closely resembles a so-called infinite flat plate (as vertical control surfaces dramatically increase RCS), the perfect stealth shape, as it would lack angles to reflect back radar waves (initially, the shape of the Northrop ATB concept was flatter; it gradually increased in volume according to specific military requirements). Without vertical surfaces to reflect radar laterally, side aspect radar cross section is also reduced. Radars operating at a lower frequency band (S or L band) are able to detect and track certain stealth aircraft that have multiple control surfaces, like canards or vertical stabilizers, where the frequency wavelength can exceed a certain threshold and cause a resonant effect. RCS reduction as a result of shape had already been observed on the
Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...
's
Avro Vulcan The Avro Vulcan (later Hawker Siddeley Vulcan from July 1963) is a jet-powered, tailless, delta-wing, high-altitude, strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe an ...
strategic bomber, and the USAF's F-117 Nighthawk. The F-117 used flat surfaces (
faceting Stella octangula as a faceting of the cube In geometry, faceting (also spelled facetting) is the process of removing parts of a polygon, polyhedron or polytope, without creating any new vertices. New edges of a faceted polyhedron may be cre ...
technique) for controlling radar returns as during its development (see Lockheed Have Blue) in the early 1970s, technology only allowed for the simulation of radar reflections on simple, flat surfaces; computing advances in the 1980s made it possible to simulate radar returns on more complex curved surfaces. The B-2 is composed of many curved and rounded surfaces across its exposed airframe to deflect radar beams. This technique, known as ''continuous curvature'', was made possible by advances in
computational fluid dynamics Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the calculations required to simulate ...
, and first tested on the Northrop Tacit Blue.


Infrared

Some analysts claim
infra-red search and track An infrared search and track (IRST) system (sometimes known as infrared sighting and tracking) is a method for detecting and tracking objects which give off infrared radiation, such as the infrared signatures of jet aircraft and helicopters. ...
systems (IRSTs) can be deployed against stealth aircraft, because any aircraft surface heats up due to air friction and with a two channel IRST is a (4.3 µm absorption maxima) detection possible, through difference comparing between the low and high channel. Burying engines deep inside the fuselage also minimizes the thermal visibility or
infrared signature Infrared signature, as used by defense scientists and the military, is the appearance of objects to infrared sensors. An infrared signature depends on many factors, including the shape and size of the object, temperature, and emissivity, reflectio ...
of the exhaust. At the engine intake, cold air from the
boundary layer In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip boundary cond ...
below the main inlet enters the fuselage (
boundary layer suction Boundary layer suction is a boundary layer control technique in which an air pump is used to extract the boundary layer at the wing or the inlet of an aircraft. Improving the air flow can reduce drag. Improvements in fuel efficiency have been est ...
, first tested on the
Northrop X-21 The Northrop X-21A was an experimental aircraft designed to test wings with laminar flow control. It was based on the Douglas WB-66D airframe, with the wing-mounted engines moved to the rear fuselage and making space for air compressors. The airc ...
) and is mixed with hot exhaust air just before the nozzles (similar to the Ryan AQM-91 Firefly). According to the
Stefan–Boltzmann law The Stefan–Boltzmann law describes the power radiated from a black body in terms of its temperature. Specifically, the Stefan–Boltzmann law states that the total energy radiated per unit surface area of a black body across all wavelengths ...
, this results in less energy (
thermal radiation Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) i ...
in the infrared spectrum) being released and thus a reduced heat signature. The resulting cooler air is conducted over a surface composed of heat resistant
carbon-fiber-reinforced polymer Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...
and
titanium alloy Titanium alloys are alloys that contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness (even at extreme temperatures). They are light in weight, have extraordinary corrosion resista ...
elements, which disperse the air laterally, to accelerate its cooling.Jane's Aircraft Upgrades 2003, p. 1711f The B-2 lacks
afterburner An afterburner (or reheat in British English) is an additional combustion component used on some jet engines, mostly those on military supersonic aircraft. Its purpose is to increase thrust, usually for supersonic flight, takeoff, and co ...
s as the hot exhaust would increase the infrared signature; breaking the
sound barrier The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, th ...
would produce an obvious
sonic boom A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to ...
as well as
aerodynamic heating Aerodynamic heating is the heating of a solid body produced by its high-speed passage through air. In science and engineering, an understanding of aerodynamic heating is necessary for predicting the behaviour of meteoroids which enter the earth's ...
of the aircraft skin which would also increase the infrared signature.


Materials

According to the Huygens–Fresnel principle, even a very flat plate would still reflect radar waves, though much less than when a signal is bouncing at a right angle. Additional reduction in its radar signature was achieved by the use of various radar-absorbent materials (RAM) to absorb and neutralize radar beams. The majority of the B-2 is made out of a
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
-
graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on lar ...
composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
that is stronger than steel, lighter than aluminum, and absorbs a significant amount of radar energy. The B-2 is assembled with unusually tight
engineering tolerance Engineering tolerance is the permissible limit or limits of variation in: # a physical dimension; # a measured value or physical property of a material, manufactured object, system, or service; # other measured values (such as temperature, hum ...
s to avoid leaks as they could increase its radar signature. Innovations such as alternate high frequency material (AHFM) and automated material application methods were also incorporated to improve the aircraft's radar-absorbent properties and reduce maintenance requirements. In early 2004, Northrop Grumman began applying a newly developed AHFM to operational B-2s. To protect the operational integrity of its sophisticated radar absorbent material and coatings, each B-2 is kept inside a climate-controlled hangar (Extra Large Deployable Aircraft Hangar System) large enough to accommodate its wingspan.Fulghum, D.A
"First F-22 large-scale, air combat exercise wins praise and triggers surprise" (online title), "Away Game".
'' Aviation Week & Space Technology'', 8 January 2007. Retrieved 13 September 2009.


Shelter system

B-2s are supported by portable, environmentally-controlled hangars called B-2 Shelter Systems (B2SS). The hangars are built by American Spaceframe Fabricators Inc. and cost approximately US$5 million apiece. The need for specialized hangars arose in 1998 when it was found that B-2s passing through Andersen Air Force Base did not have the climate-controlled environment maintenance operations required. In 2003, the B2SS program was managed by the Combat Support System Program Office at Eglin Air Force Base. B2SS hangars are known to have been deployed to
Naval Support Facility Diego Garcia Naval Support Facility Diego Garcia is a British Ministry of Defence facility leased to the United States Navy, located on the atoll Diego Garcia in the Indian Ocean. Camp Thunder Cove is part of the facility, and is operated by the United Sta ...
and
RAF Fairford Royal Air Force Fairford or more simply RAF Fairford is a Royal Air Force (RAF) station in Gloucestershire, England which is currently a standby airfield and therefore not in everyday use. Its most prominent use in recent years has been as an ...
.


Operational history


1990s

The first operational aircraft, christened ''Spirit of Missouri'', was delivered to
Whiteman Air Force Base Whiteman Air Force Base is a United States Air Force base located just south of Knob Noster, Missouri, United States. The base is the current home of the B-2 Spirit bomber. It is named for 2nd Lt George Whiteman, who was killed during the attac ...
,
Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ...
, where the fleet is based, on 17 December 1993. The B-2 reached initial operational capability (IOC) on 1 January 1997. Depot maintenance for the B-2 is accomplished by USAF contractor support and managed at
Oklahoma City Air Logistics Center The Oklahoma City Air Logistics Complex (OC-ALC) Tinker Air Force Base, Oklahoma is one of the largest units in the Air Force Materiel Command. The complex performs programmed depot maintenance on the C/KC-135, B-1B, B-52 and E-3 aircraft; expande ...
at
Tinker Air Force Base Tinker Air Force Base is a major United States Air Force base, with tenant U.S. Navy and other Department of Defense missions, located in Oklahoma County, Oklahoma, surrounded by Del City, Oklahoma City, and Midwest City. The base, origina ...
."B-2 Spirit Fact Sheet."
''U.S. Air Force''. Retrieved 8 January 2015.
Originally designed to deliver nuclear weapons, modern usage has shifted towards a flexible role with conventional and nuclear capability. The B-2's combat debut was in 1999, during the
Kosovo War The Kosovo War was an armed conflict in Kosovo that started 28 February 1998 and lasted until 11 June 1999. It was fought by the forces of the Federal Republic of Yugoslavia (i.e. Serbia and Montenegro), which controlled Kosovo before the wa ...
. It was responsible for destroying 33% of selected Serbian bombing
targets ''Targets'' is a 1968 American crime thriller film directed by Peter Bogdanovich, produced by Roger Corman, and written by Polly Platt and Bogdanovich, with cinematography by László Kovács.Stephen Jacobs, ''Boris Karloff: More Than a Monster' ...
in the first eight weeks of U.S. involvement in the War. During this war, six B-2s flew non-stop to Yugoslavia from their home base in Missouri and back, totaling 30 hours. Although the bombers accounted 50 sorties out of a total of 34,000 NATO sorties, they dropped 11 percent of all bombs. The B-2 was the first aircraft to deploy GPS satellite-guided JDAM "smart bombs" in combat use in Kosovo. The use of JDAMs and precision-guided munitions effectively replaced the controversial tactic of
carpet-bombing Carpet bombing, also known as saturation bombing, is a large area bombardment done in a progressive manner to inflict damage in every part of a selected area of land. The phrase evokes the image of explosions completely covering an area, in t ...
, which had been harshly criticized due to it causing indiscriminate civilian casualties in prior conflicts, such as the 1991
Gulf War The Gulf War was a 1990–1991 armed campaign waged by a Coalition of the Gulf War, 35-country military coalition in response to the Iraqi invasion of Kuwait. Spearheaded by the United States, the coalition's efforts against Ba'athist Iraq, ...
. On 7 May 1999, a B-2 dropped five JDAMs on the Chinese Embassy, killing several staff. By then, the B-2 had dropped 500 bombs in Yugoslavia.


2000s

The B-2 saw service in
Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
, striking ground targets in support of Operation Enduring Freedom. With aerial refueling support, the B-2 flew one of its longest missions to date from Whiteman Air Force Base in Missouri to Afghanistan and back. B-2s would be stationed in the Middle East as a part of a US military buildup in the region from 2003. The B-2's combat use preceded a USAF declaration of "full operational capability" in December 2003. The Pentagon's Operational Test and Evaluation 2003 Annual Report noted that the B-2's serviceability for Fiscal Year 2003 was still inadequate, mainly due to the maintainability of the B-2's low observable coatings. The evaluation also noted that the Defensive Avionics suite had shortcomings with "pop-up threats". During the
Iraq War {{Infobox military conflict , conflict = Iraq War {{Nobold, {{lang, ar, حرب العراق (Arabic) {{Nobold, {{lang, ku, شەڕی عێراق ( Kurdish) , partof = the Iraq conflict and the War on terror , image ...
, B-2s operated from
Diego Garcia Diego Garcia is an island of the British Indian Ocean Territory, a disputed overseas territory of the United Kingdom. It is a militarised atoll just south of the equator in the central Indian Ocean, and the largest of the 60 small islands of ...
and an undisclosed "forward operating location". Other sorties in Iraq have launched from Whiteman AFB. the longest combat mission has been 44.3 hours. "Forward operating locations" have been previously designated as Andersen Air Force Base in
Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
and
RAF Fairford Royal Air Force Fairford or more simply RAF Fairford is a Royal Air Force (RAF) station in Gloucestershire, England which is currently a standby airfield and therefore not in everyday use. Its most prominent use in recent years has been as an ...
in the United Kingdom, where new climate controlled hangars have been constructed. B-2s have conducted 27 sorties from Whiteman AFB and 22 sorties from a forward operating location, releasing more than of munitions, including 583 JDAM "smart bombs" in 2003."Air Force programs: B-2."
''Project On Government Oversight'' (POGO), 16 April 2004. Retrieved 13 September 2009.


2010s

In response to organizational issues and high-profile mistakes made within the USAF, all of the B-2s, along with the nuclear-capable B-52s and the USAF's intercontinental ballistic missiles (ICBMs), were transferred to the newly formed Air Force Global Strike Command on 1 February 2010. In March 2011, B-2s were the first U.S. aircraft into action in Operation Odyssey Dawn, the UN mandated enforcement of the Libyan no-fly zone. Three B-2s dropped 40 bombs on a Libyan airfield in support of the UN no-fly zone.Martin, David
"Crisis in Libya: U.S. bombs Qaddafi's airfields."
CBS News, 20 March 2011.
The B-2s flew directly from the U.S. mainland across the Atlantic Ocean to Libya; a B-2 was refueled by allied tanker aircraft four times during each round trip mission. In August 2011, ''
The New Yorker ''The New Yorker'' is an American weekly magazine featuring journalism, commentary, criticism, essays, fiction, satire, cartoons, and poetry. Founded as a weekly in 1925, the magazine is published 47 times annually, with five of these issues ...
'' reported that prior to the May 2011 U.S. Special Operations raid into Abbottabad,
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...
that resulted in the
death of Osama bin Laden On May 2, 2011, Osama bin Laden, the founder and first leader of the Islamist militant group al-Qaeda, was shot several times and killed at his compound in the Pakistani city of Abbottabad, by United States Navy SEALs of the U.S. Naval Spe ...
, U.S. officials had considered an airstrike by one or more B-2s as an alternative; the use of a bunker busting bomb was rejected due to potential damage to nearby civilian buildings. There were also concerns an airstrike would make it difficult to positively identify Bin Laden's remains, making it hard to confirm his death. On 28 March 2013, two B-2s flew a round trip of from Whiteman Air Force base in Missouri to South Korea, dropping dummy ordnance on the Jik Do target range. The mission, part of the annual South Korean–United States military exercises, was the first time that B-2s overflew the Korean peninsula. Tensions between the Koreas were high; North Korea protested against the B-2's participation and made threats of retaliatory nuclear strikes against South Korea and the United States. On 18 January 2017, two B-2s attacked an ISIS training camp southwest of Sirte, Libya, killing around 85 militants. The B-2s together dropped 108 precision-guided Joint Direct Attack Munition (JDAM) bombs. These strikes were followed by an MQ-9 Reaper unmanned aerial vehicle firing Hellfire missiles. Each B-2 flew a 33-hour, round-trip mission from Whiteman Air Force Base, Missouri with four or five (accounts differ) refuelings during the trip.


Operators

United States Air Force The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...
(20 aircraft in active inventory) : Air Force Global Strike Command *
509th Bomb Wing The 509th Bomb Wing (509 BW) is a United States Air Force unit assigned to the Air Force Global Strike Command, Eighth Air Force. It is stationed at Whiteman Air Force Base, Missouri. The 509 BW is the host unit at Whiteman, and operates th ...
Whiteman Air Force Base Whiteman Air Force Base is a United States Air Force base located just south of Knob Noster, Missouri, United States. The base is the current home of the B-2 Spirit bomber. It is named for 2nd Lt George Whiteman, who was killed during the attac ...
,
Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ...
(19 B-2s) ::
13th Bomb Squadron The 13th Bomb Squadron is a squadron of the United States Air Force. It is assigned to the 509th Operations Group, Air Force Global Strike Command, stationed at Whiteman Air Force Base, Missouri. The squadron is equipped with the Northrop Gru ...
2005–present ::325th Bomb Squadron 1998–2005 ::
393rd Bomb Squadron The 393rd Bomb SquadronOfficially, the 393d Bomb Squadron is part of the 509th Bomb Wing at Whiteman Air Force Base, Missouri. It operates Northrop Grumman B-2 Spirit nuclear-capable strategic bomber aircraft. The squadron was first organiz ...
1993–present ::
394th Combat Training Squadron The 394th Combat Training Squadron was a United States Air Force unit assigned to the 509th Operations Group until inactivated on 13 April 2018. It was stationed at Whiteman Air Force Base, Missouri. The mission of the squadron was to trai ...
1996–2018 : Air Combat Command * 53d WingEglin Air Force Base, Florida ::
72nd Test and Evaluation Squadron The 72d Test and Evaluation Squadron is part of the 53d Wing at Eglin Air Force Base, Florida. The squadron is geographically separated but operated from Whiteman Air Force Base, Missouri. It conducts testing and evaluation of the B-2 Spi ...
(Whiteman AFB, Missouri) 1998–present * 57th Wing
Nellis AFB Nellis Air Force Base ("Nellis" colloq.) is a United States Air Force installation in southern Nevada. Nellis hosts air combat exercises such as Exercise Red Flag and close air support exercises such as Green Flag-West flown in " Military Op ...
,
Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
:: 325th Weapons Squadron – Whiteman AFB, Missouri 2005–present :: 715th Weapons Squadron 2003–2005 : Air National Guard *
131st Bomb Wing The 131st Bomb Wing is a unit of the Missouri Air National Guard, stationed at Whiteman Air Force Base, Knob Noster, Missouri. If activated to federal service, the wing is gained by the United States Air Force Global Strike Command. It is an a ...
(Associate) – Whiteman AFB, Missouri 2009–present :: 110th Bomb Squadron : Air Force Materiel Command *
412th Test Wing The 412th Test Wing (412 TW) is a wing of the United States Air Force, assigned to the Air Force Test Center at Edwards Air Force Base, California. Overview The 412th Test Wing plans, conducts, analyzes, and reports on all flight and ground te ...
Edwards Air Force Base, California (has one B-2) :: 419th Flight Test Squadron 1997–present ::
420th Flight Test Squadron 4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. In mathematics Four is the smallest c ...
1992–1997 : Air Force Systems Command * 6510th Test Wing – Edwards AFB, California 1989–1992 ::6520th Flight Test Squadron


Accidents and incidents

On 23 February 2008, B-2 "AV-12" ''Spirit of Kansas'' crashed on the runway shortly after takeoff from Andersen Air Force Base in
Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
."B-2 Crashes on Takeoff From Guam."
''Aviation Week'', 23 February 2008. Retrieved 13 September 2009.
''Spirit of Kansas'' had been operated by the
393rd Bomb Squadron The 393rd Bomb SquadronOfficially, the 393d Bomb Squadron is part of the 509th Bomb Wing at Whiteman Air Force Base, Missouri. It operates Northrop Grumman B-2 Spirit nuclear-capable strategic bomber aircraft. The squadron was first organiz ...
,
509th Bomb Wing The 509th Bomb Wing (509 BW) is a United States Air Force unit assigned to the Air Force Global Strike Command, Eighth Air Force. It is stationed at Whiteman Air Force Base, Missouri. The 509 BW is the host unit at Whiteman, and operates th ...
,
Whiteman Air Force Base Whiteman Air Force Base is a United States Air Force base located just south of Knob Noster, Missouri, United States. The base is the current home of the B-2 Spirit bomber. It is named for 2nd Lt George Whiteman, who was killed during the attac ...
, Missouri, and had logged 5,176 flight hours. The two-person crew ejected safely from the aircraft. The aircraft was destroyed, a
hull loss A hull loss is an aviation accident that catastrophically damages the aircraft beyond economical repair, resulting in a total loss. The term also applies to situations in which the aircraft is missing, the search for their wreckage is terminate ...
valued at US$1.4 billion. After the accident, the USAF took the B-2 fleet off operational status for 53 days, returning on 15 April 2008. The cause of the crash was later determined to be moisture in the aircraft's Port Transducer Units during air data calibration, which distorted the information being sent to the bomber's air data system. As a result, the flight control computers calculated an inaccurate airspeed, and a negative angle of attack, causing the aircraft to pitch upward 30 degrees during takeoff. This was the first crash of a B-2 and the only loss . In February 2010, a serious incident involving a B-2 occurred at Andersen Air Force Base in Guam. The aircraft involved was AV-11 ''Spirit of Washington''. The aircraft was severely damaged by fire while on the ground and underwent 18 months of repairs to enable it to fly back to the mainland U.S. for more comprehensive repairs.jeremigio
"B-2 Fire at AAFB Back in February of 2010 Was 'Horrific,' Not 'Minor'."
''pncguam.com'', 31 August 2011. Retrieved 8 May 2020.
''Spirit of Washington'' was repaired and returned to service in December 2013. At the time of the accident the USAF had no training to deal with tailpipe fires on the B-2s. On the night of 13–14 September 2021, the B-2 ''Spirit of Georgia'' made an
emergency landing An emergency landing is a premature landing made by an aircraft in response to an emergency involving an imminent or ongoing threat to the safety and operation of the aircraft, or involving a sudden need for a passenger or crew on board to term ...
at Whiteman AFB. The aircraft landed and went off the runway into the grass and came to rest on its left side. The cause was later determined to be faulty landing gear springs and "microcracking" in hydraulic connections on the aircraft. The lock link springs in the left landing gear had likely not been replaced in at least a decade, and produced about 11% less tension than specified. The "microcracking" reduced hydraulic support to the landing gear. These problems allowed the landing gear to fold upon landing. The accident resulted in a minimum of $10.1 million in repair damages, but the final repair cost was still being determined in March 2022. On 10 December 2022, an in-flight malfunction aboard a B-2 forced an emergency landing at Whiteman AFB. No personnel, including the flight crew, sustained injuries during the incident; there was a post-crash fire that was quickly put out. In mid-December 2022, there are no reports of what caused the malfunction, or the cost of the damage, but the incident is being investigated. Subsequently all B-2s have been grounded.


Aircraft on display

No operational B-2s have been retired by the Air Force to be put on display. B-2s have made occasional appearances on ground display at various air shows. B-2 test article (s/n AT-1000), the second of two built without engines or instruments and used for static testing, was placed on display in 2004 at the
National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is the ...
near
Dayton, Ohio Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater D ...
."Factsheet: Northrop B-2 Spirit."
''National Museum of the United States Air Force.'' Retrieved: 24 August 2011.
The test article passed all structural testing requirements before the airframe failed. The museum's restoration team spent over a year reassembling the fractured airframe. The display airframe is marked to resemble ''Spirit of Ohio'' (S/N 82-1070), the B-2 used to test the design's ability to withstand extreme heat and cold. The exhibit features ''Spirit of Ohio''s nose wheel door, with its ''Fire and Ice'' artwork, which was painted and signed by the technicians who performed the temperature testing. The restored test aircraft is on display in the museum's "Cold War Gallery".


Specifications (B-2A Block 30)


Individual aircraft

Sources: B-2 Spirit (Pace), Fas.org
''fas.org''. Retrieved 16 June 2010.


Notable appearances in media


See also


References


Notes


Bibliography


"Air Force, Options to Retire or Restructure the Force Would Reduce Planned Spending, NSIAD-96-192."
''US General Accounting Office'', September 1996. * * * Crickmore, Paul and Alison J. Crickmore, "Nighthawk F-117 Stealth Fighter". North Branch, Minnesota: Zenith Imprint, 2003. . * Croddy, Eric and James J. Wirtz. ''Weapons of Mass Destruction: An Encyclopedia of Worldwide Policy, Technology, and History, Volume 2''. Santa Barbara, California: ABC-CLIO, 2005. . * Dawson, T.W.G., G.F. Kitchen and G.B. Glider
''Measurements of the Radar Echoing Area of the Vulcan by the Optical Simulation Method.''
Farnborough, Hants, UK: Royal Aircraft Establishment, September 1957 National Archive Catalogue file, AVIA 6/20895 * * * Eden, Paul. "Northrop Grumman B-2 Spirit". ''Encyclopedia of Modern Military Aircraft''. New York: Amber Books, 2004. . * * * Goodall, James C. "The Northrop B-2A Stealth Bomber." ''America's Stealth Fighters and Bombers: B-2, F-117, YF-22, and YF-23''. St. Paul, Minnesota: MBI Publishing Company, 1992. . * * * * Pelletier, Alain J. "Towards the Ideal Aircraft: The Life and Times of the Flying Wing, Part Two". ''
Air Enthusiast ''Air Enthusiast'' was a British, bi-monthly, aviation magazine, published by the Key Publishing group. Initially begun in 1974 as ''Air Enthusiast Quarterly'', the magazine was conceived as a historical adjunct to ''Air International'' maga ...
'', No. 65, September–October 1996, pp. 8–19. . * * * * * * * * * Sweetman, Bill. "Inside the stealth bomber". Zenith Imprint, 1999. . * *


Further reading

* Richardson, Doug. ''Northrop B-2 Spirit'' (Classic Warplanes). New York: Smithmark Publishers Inc., 1991. . * Sweetman, Bill. ''Inside the Stealth Bomber''. St. Paul, Minnesota: MBI Publishing, 1999. . * Winchester, Jim, ed. "Northrop B-2 Spirit". ''Modern Military Aircraft'' (Aviation Factfile). Rochester, Kent, UK: Grange Books plc, 2004. . * ''The World's Great Stealth and Reconnaissance Aircraft''. New York: Smithmark, 1991. .


External links


B-2 Spirit fact sheet
an
gallery on U.S. Air Force site



B-2 Stealth Bomber article on How It Works Daily

B-2 Spirit News Articles
{{Authority control B-02 Spirit B-02 Spirit 1980s United States bomber aircraft Flying wings Stealth aircraft Quadjets Relaxed-stability aircraft Aircraft first flown in 1989 High-altitude and long endurance aircraft Strategic bombers