Northrop Grumman B-2 Spirit Stealth Bomber
Northrop Grumman B-2 Spirit Stealth Bomber
v1.1.1 / 01 aug 23 / greg goebel
* During the late 1940s and early 1950s, Jack Northrop of the Northrop
company worked on a series of flying-wing bombers, none of which actually
reached production. However, they did attract a great deal of public
attention, being seen as futuristic, and were even featured in
science-fiction movies such as THE WAR OF THE WORLDS.
A few decades later the notion that the future belonged to the flying wing
seemed laughable, but Northrop had the last laugh. There were tales that
radar had trouble picking up the uncluttered lines of a flying wing, and as
the US Air Force turned towards "stealthy" aircraft in the 1970s and 1980s,
the flying wing bomber was revived in the form of the Northrop Grumman "B-2
Spirit" -- the first flying wing to enter full operational service, the
biggest stealth aircraft built to date, and one of the most expensive
aircraft ever made. A list of illustration credits is provided at the end.
[1] B-2 ORIGINS: PROJECT HARVEY / TACIT BLUE / ATB
[2] B-2 DESCRIBED
[3] B-2 IN SERVICE
[4] COMMENTS, SOURCES, & REVISION HISTORY
* Formal work on the development of "low-observable" or "stealth' aircraft in
the US began in late 1974, when the Defense Advanced Research Projects Agency
(DARPA), a Pentagon organization that works on "blue sky" advanced
technologies, began Project HARVEY, an effort to build a stealthy aircraft.
The project was named after a famous comedy about a giant invisible rabbit
named, of course, Harvey.
Project HARVEY was not actually the first time the US had incorporated
stealth features into aircraft. In the early 1960s, Firebee target drones
had been modified for the reconnaissance role as "Lightning Bugs" or
"Fireflies". They had been given stealth enhancements, including pads of
radar-absorbing material (RAM) on the sides of the fuselage; and a wire mesh
over the air intake to mask the blades of the engine compressor, which tends
to sparkle or "glint" on radar as it spins, like a spinning disco ball in a
lights show. The high-flying Lockheed SR-71 Blackbird reconnaissance
aircraft was designed to be stealthy as well, though it also used high
altitude and speed for protection.
The goals of Project HARVEY were much more ambitious: to create an aircraft
that could survive on stealth alone. DARPA awarded study contracts to
McDonnell Douglas and Northrop in January 1975. Lockheed officials found out
about HARVEY through the grapevine and insisted on participating, paying for
their design effort out of company funds. That was a gamble, but it paid
off: Northrop and Lockheed were selected by DARPA to design a stealth
demonstrator, the "Experimental Survivable Testbed (XST)", while McDonnell
Douglas was eliminated from the competition. The XST program's goals did not
include building a flight demonstrator; Northrop and Lockheed were to build
large-scale mockups, which would then be mounted on a pole at Holloman AFB in
New Mexico and subjected to tests to determine their "radar cross-section
(RCS)".
Work on the Northrop demonstrator was conducted by a team under John Cashen,
a pushy sort who had come to Northrop after working at Hughes on how targets
appeared to radar and infrared sensors, and Irv Waaland, a designer who had
come over to Northrop from Grumman. Although the Lockheed team used a
computer program to come up with their design for the XST, Cashen said later
that Northrop didn't have such a luxury, and worked up their design using a
combination of theoretical analysis and cut-and-try experiments.
The Lockheed team won the XST competition in March 1976, and went on to build
two HAVE BLUE stealth demonstrator aircraft, which paved the way to the
larger Lockheed F-117 stealth fighter. Northrop lost because one of the
team's initial design assumptions was that a stealthy aircraft should be
hardest to pick up from the front and below, but the DARPA requirement,
rightly or wrongly, insisted on measuring stealthiness from four quadrants.
The Lockheed design proved better able to meet the all-round stealth
requirement. Lockheed also had an advantage in possessing a good knowledge
of RAM technology, which that company had developed for the SR-71.
However, in December 1976, DARPA officials called up Northrop to discuss a
stealth aircraft as part of the Pentagon's ASSAULT BREAKER effort. ASSAULT
BREAKER was a wide-ranging program that envisioned use of new "smart"
munitions, deep-penetrating strike platforms, and advanced sensors to smash
numerically-superior Soviet armor forces in the case of a European war.
DARPA wanted Northrop to study a stealthy "Battlefield Surveillance Aircraft
-- Experimental (BSAX)" that would spot targets for ASSAULT BREAKER weapons.
Since BSAX was supposed to loiter around a battlefield instead of performing
an attack and leaving, it would present all angles to an enemy, and so
required all-round stealth. An initial model of BSAX was tested in the
summer of 1977, with results that Waaland later described as "disastrous".
One of the design team members, Fred Oshira, did some rethinking of the
design and came up with a solution, a new airframe design that gave very
little for a radar beam to grab on to. In April 1978, DARPA awarded Northrop
a contract for a single flying prototype of the design, which was given the
codename TACIT BLUE.
TACIT BLUE performed its initial flight in February 1982, followed by 134
more flights over a three-year evaluation. It was unarguably one of the
ugliest aircraft ever built, unflatteringly known as the "Whale". It
featured a fuselage resembling a stretched upside-down bathtub with:
- Wedge-shaped wings and a wedge-shaped flat panel under the nose.
- An engine intake buried in the back, with a serpentine inlet to conceal
the engine fan from radar
- "Platypus" exhausts to cool the exhaust stream, and a vee tail shielding
the exhaust.
TACIT BLUE was highly unstable -- a wind-tunnel model flipped around -- and
required a fly-by-wire control system to keep it in the air. TACIT BLUE was
powered by twin Garrett ATF3 turbofan engines, used on some business jets,
with a take-off thrust of 24.3 kN (2,465 kgp / 5,440 pounds) each. It had a
wingspan of 14.7 meters (48 feet 2 inches), a length of 17 meters (55 feet 10
inches), and a weight of 13,605 kilograms (30,000 pounds).
The Hughes surveillance radar carried by TACIT BLUE featured "low probability
of intercept (LPI)" operation, with the radar dancing over frequencies and
changing pulse patterns so that its signals couldn't be easily picked out of
background noise. Apparently the TACIT BLUE program did much to advance LPI
radar technology; it would have made absolutely no sense to design a stealthy
battlefield surveillance aircraft, and then have it announce its presence by
blasting out strong and easily detected radar signals. An LPI radar was also
harder to jam or spoof. During test flights, other aircraft never sensed the
radar. The radar data was sent to a ground station through a one-way
datalink.
Tests with a pole model to check the RCS of TACIT BLUE gave wildly high
results, until the test crew discovered an owl had landed on the model. An
F-15 fighter tried to track TACIT BLUE on radar and couldn't do it, except if
it was within visual range anyway. It was also quiet, the turbofan engines
not making much noise.
In 1984, the Army and Air Force decided to collaborate on a non-stealthy
battlefield surveillance platform, which would emerge as the E-8 Joint Stars,
based on the Boeing 707 airliner. TACIT BLUE was retired and put into
storage. It was finally announced to the public in 1996, and put on display
in the USAF Museum at Wright Patterson Air Force Base in Ohio a decade later.
* While Northrop was beginning work on TACIT BLUE, back at the Pentagon the
top brass were becoming very interested in stealth. In 1977, William "Bill"
Perry, Secretary of Defense for the Carter Administration, formed a group to
perform studies on the military potential of stealth. The group's conclusion
was that improvements in adversary air defenses were threatening to make the
current "non-stealthy" US bomber force obsolete. In addition, stealth would
allow a single aircraft to make a precision attack on a target, instead of
requiring a full "strike package" of multiple bombers, with fighter escorts,
jamming platforms, and defense-suppression ("Wild Weasel") aircraft.
The group recommended that two stealthy strike aircraft should be built, an
"A Airplane", a fast-track development of the Lockheed HAVE BLUE
demonstrator, which would emerge as the F-117; and a "B Airplane" that would
be bigger and more capable, but would take more time to roll out.
The B Airplane concept grew over time into a full-blown, long-range heavy
bomber. Lockheed had proposals, one apparently being a machine something
like a scaled-up F-117 and codenamed SENIOR PEG, but the Pentagon also asked
Northrop to investigate. Northrop officials were uneasy about working on a
heavy bomber, since the company's last effort along such lines, the XB-35 /
YB-49 flying wings of three decades earlier, had come close to financially
wrecking the company. They did agree, however, and responded with two
proposals -- one of which, cooked up by designer Hal Markarian, took its
inspiration from the YB-49. Incidentally, there is a story, possibly true,
that the YB-49 had shown a surprising ability to disappear from radar at
certain viewing angles.
The proposals were duly submitted in August 1979, and Bill Perry came back
with a study contract, asking Northrop to refine the flying wing concept.
Waaland joined up with Markarian, and the team also acquired aerodynamicist
Hans Grellman, as well as Dick Scherrer, a designer who had recently come
over from Lockheed. At the outset, the Northrop "Advanced Strategic
Penetration Aircraft (ASPA)", as it was known, was seen strictly as an
insurance policy, since Lockheed was regarded by the brass as the
front-runner.
However, by the time the Air Force issued a request for an "Advanced
Technology Bomber" in September 1980, formalizing the ASPA studies into a
program to develop an operational aircraft, Northrop's design was looking
much more attractive, and company officials felt they had a shot at winning
the contract. Lockheed was partnering with Raytheon on their ATB proposal,
and so Northrop approached Boeing to sign up as a partner. Northrop's
chairman, Tom Jones, had a meeting with his counterpart at Boeing, Thornton
Wilson. Wilson, to his embarrassment, was almost completely ignorant of the
ATB program -- but Jones filled him in, and Wilson agreed to join
immediately. Witnesses claim that Wilson then turned to one of his people
and said: "Don't
ever
let me be caught in this position again!"
The Northrop concept, codenamed SENIOR ICE, was judged superior to the
Lockheed SENIOR PEG proposal, and Northrop won the ATB contract in October
1981. The contract covered delivery of two static-test airframes, one flying
prototype, and five evaluation machines. While the Carter Administration had
pushed stealth, there had been some ambivalence about production, but the
new, hawkish Reagan Administration wanted to go full speed ahead on the ATB.
The initial plan envisioned production of 127 ATBs, in addition to the five
evaluation machines, which would be brought up to operational specification.
The Pentagon wanted to keep the contract a secret, but Tom Jones pointed out
that Northrop had to publicly declare large company contracts in order to be
in compliance with securities laws. Government officials, caught by their
own regulations, issued the shortest and least informative statement possible
about the contract. It would be the last public mention of the program until
1988.
* There was much more work to be done to get such a complicated machine into
the air, all the more so because the ATB requirements had expanded over time.
Aircraft size and munitions load had grown, and although the ATB was
originally seen as a high-altitude penetration machine, the Air Force decided
that a low altitude capability would be nice as well -- there was no saying
that the Soviets might eventually develop more powerful and smarter radars
that could pick up a high-flying stealthy aircraft.
In any case, the work went forward, and the first "B-2" prototype, "Air
Vehicle One (AV-1)", was rolled out at the Northrop plant in Palmdale,
California, on 22 November 1988. The rollout was public, but observers were
restricted to stands that kept them well away from the aircraft and limited
their view of it to the front. Although the F-117 had been kept secret for
years after its first flight, its test flights had been restricted to night,
and that wasn't regarded as acceptable for the B-2. Since it would have been
quickly spotted during daylight flights, there was no sense in keeping it a
complete secret, and nobody tried.
However, the security restrictions at the rollout weren't completely
"airtight", in a highly literal sense of the word. Michael A. Dornheim, a
reporter from AVIATION WEEK magazine, flew a light aircraft over the B-2 and
had a photographer take pictures, obtaining one of the magazine's biggest
scoops of all time, and justifying its nickname of AVIATION LEAK. It was all
perfectly legal. The damage, if any, had been done, and the program went
forward.
AV-1 performed its first flight on 17 July 1989, flying from Palmdale to
Edwards AFB in California. Northrop Test pilot Bruce Hinds and USAF Colonel
Richard Couch were at the controls. AV-2, the first of the five evaluation
machines, performed its initial flight on 19 October 1990. The first
production B-2A was accepted by the US Air Force Air Combat Command (USAF
ACC) at Whiteman AFB in Missouri on 17 December 1993. Due to the merger of
Northrop and Grumman in the 1990s, the aircraft is now the "Northrop Grumman
B-2".
BACK_TO_TOP
* As it emerged, the B-2 was "organic" in appearance, a simple flying wing,
with absolutely no vertical control surfaces. It had very smooth contours,
with few features that could "catch" radar waves and reflect them. It
featured a sweepback of 55 degrees, and a zigzag trailing edge. The aircraft
was aerodynamically unstable, kept in the air with a quadruple-redundant
fly-by-wire (FBW) system, under the control of a General Electric Flight
Control Computer (FCC).
The B-2 was designed to be survivable, not merely in penetrating enemy
airspace and performing attacks, but in riding out enemy nuclear attacks or
counterstrikes. It was thoroughly radiation hardened; Waaland commented that
about all that wasn't radiation hardened was the antiskid braking system. It
could also operate from dispersed bases, one of the design criteria being the
capability to use any airstrip capable of supporting a Boeing 727 airliner.
The aerodynamic efficiency of a flying wing allowed use of relatively short
runways.
The B-2 made heavy use of titanium for structural elements, with much of the
rest of the aircraft built of carbon-reinforced plastic (CRP) material.
Large CRP skin assemblies were used to make the aircraft as "seamless" as
possible, reducing radar reflections. The principle of seamlessness also
meant that the number of access panels was minimized, reversing the trend of
the past decades to provide maximum maintenance access. Maintenance access
was mostly provided through absolutely essential apertures, such as the
bomb bays and crew boarding hatch. There were also no drain holes, with
drainage flowing into collectors that were emptied by ground crew.
Designing the CRP assemblies, tooling up for their production, and fitting
them in place in aircraft manufacture was a major engineering challenge.
Special heat-resistant CRP formulations were used around engine exhausts and
other hot spots, where carbon-reinforced epoxy simply wouldn't do. The
aircraft was initially coated with a conductive elastomer material to ensure
that it had uniform electrical conductivity. This material was not actually
RAM, but RAM was used selectively where needed. The B-2 was painted in a
bluish-gray anti-reflective paint to reduce its visual signature; it was not
painted black, as was the F-117, since the B-2 was expected to perform both
daylight and night attacks, and black is a high-visibility color for daylight
flight operations.
The leading edge of the wing had an internal structure that helped it absorb
radar energy. The outermost wing segment featured a "rudderon" or
"deceleron" -- a vertically-split airbrake / rudder that simultaneously
opened up and down. To act as an airbrake, both the decelerons were opened,
while to act as a rudder, only one was. This clever gimmick went back to the
original Northrop flying wings. There was an "elevon" (elevator-aileron)
inboard of the deceleron on the outermost segment of each wing, and then two
elevons further inboard, on the next segment. Finally, there was a single
control surface for pitch control on the "beavertail" at the center end of
the aircraft, giving a total of nine control surfaces.
The decelerons had to be opened about five degrees before they were
effective, and in normal cruising flight they were left slightly open.
However, this undermined stealth, so when the bomber was in hostile airspace,
it used differential engine thrust for yaw control.
* The B-2's four General Electric F118-GE-100 non-afterburning bypass
turbojets, providing 84.56 kN (8,620 kgp / 19,000 lbf) of thrust each, were
derived from the popular GE F110 engine. The F118s were buried in the wings,
with two engines clustered together inboard on each wing. An AlliedSignal
auxiliary power unit was fitted on the forward end of the left engine
assembly
for engine starting and ground power. The B-2 also featured a built-in halon
engine fire extinguishing system.
The engine intakes and exhausts were on the top of the wings for concealment.
The intakes had a zigzag lip to scatter radar reflections, and there was a
zigzag slot just before each intake to act as a "boundary layer splitter" --
breaking up the stagnant turbulent airflow that tends to collect on the
surface of an aircraft. The inlet ducts were built as an S-curve, and lined
with RAM to keep radar reflections off the compressor blades.
The exhaust was mixed with airflow obtained through the boundary layer
splitter slot to reduce the infrared signature. The aircraft was also
designed to eliminate its contrail, with a tank outboard of the main landing
gear to store a chemical that would be mixed with the exhaust flow to
suppress the formation of a contrail. This scheme wasn't actually used in
practice, with a "lidar" (laser radar) system instead eventually developed to
detect formation of a contrail, and alert the pilot to descend to lower
altitude. That left an empty bay in each wing, which apparently would never
be used.
__________________________________________________________________
NORTHROP GRUMMAN B-2A:
__________________________________________________________________
wingspan:
52.43 meters (172 feet)
wing area:
490.05 sq_meters (5,275 sq_feet)
length:
21.03 meters (69 feet)
height:
5.18 meters (17 feet)
empty weight:
45,400 kilograms (100,000 pounds)
max loaded weight:
181,400 kilograms (400,000 pounds)
maximum speed:
764 KPH (475 MPH / 416 KT)
service ceiling:
+15,240 meters (+50,000 feet)
range:
11,675 kilometers (7,255 MI / 6,310 NMI)
__________________________________________________________________
The B-2 had tricycle landing gear, with twin-wheel nose gear and four-wheel
bogey systems for the main gear. The main gear was built by Boeing, being
derived from that used on the Boeing 767 airliner. The landing gear doors
had stealthy zigzag leading and trailing edges. Since it was difficult to
find a place on the smoothly-contoured airframe to paint such "display" items
as the aircraft name or serial number, they were painted on the main gear
outer doors, making them visible to onlookers when the aircraft was on the
ground, or during take-off and landing. There was a boom-refueling port in
the center of the back, which was normally covered by doors and popped up
when needed.
* The B-2 was fitted with two side-by-side weapons bays that could
accommodate a total of 22,680 kilograms (50,000 pounds) of stores. The
leading and trailing edges of the weapons bay doors had the classic stealthy
zigzag pattern. When the doors were open, twin grilles popped out into the
airstream at the front of each weapons bay to ensure proper stores
separation. Each of the two weapons bays could be fitted with a Boeing
Advanced Rotary Launcher (ARL), capable of carrying eight 1,000-kilogram
(2,200-pound) class munitions, or a Bomb Rack Assembly (BRA) for carriage of
smaller munitions.
Since the B-2 was originally designed for the strategic bombing role, it was
qualified initially for nuclear stores such as the B83 strategic nuclear
bomb, with selectable yield in the megaton range, and the smaller B61
"Silver Bullet" nuclear bomb, with selectable yield in the range of hundreds
of kilotons. The bomber was later qualified for the penetrating B61-11
penetrating nuclear weapon. A B-2 could carry 16 nuclear stores.
The B-2 was also qualified for use with "dumb" bombs, such as sixteen
900-kilogram (2,000-pound) bombs, or eighty 225-kilogram (500-pound) bombs or
cluster munitions based on the Tactical Munitions Dispenser (TMD). However,
such stores were likely better carried by other platforms such as the B-52 or
B-1B, and so the emphasis with the B-2 was on precision-guided weapons. Some
sources have stated it could also carry the AGM-84 Harpoon antiship missile
for maritime strike, but it seems more likely that the Harpoon was simply
listed as a potential store as a political expedient to emphasize additional
roles for the B-2. It is unclear if a B-2 has ever fired a Harpoon.
A Global Positioning System (GPS) guided bomb, the "GPS Aided Munition
(GAM)", was developed on a fast-track basis for the B-2, but GAM was strictly
an interim fix until the real solution, the "Joint Direct Attack Munition
(JDAM)", was introduced in the late 1990s. JDAM was initially a 900-kilogram
bomb fitted with gliding strakes and GPS guidance; kits were later introduced
for 225-kilogram bombs as well. The B-2 could also carry the AGM-154 Joint
Stand-Off Weapon (JSOW) glide bomb, and the AGM-158 Joint Air to Surface
Standoff Missile (JASSM).
* The B-2 was highly automated and only required two crew. A centerbody
provided crew accommodation, with crew access through a hatch in the belly.
The cockpit had large windows -- so large in fact that they tended to make
the
B-2 look smaller than it really is, though the downward view is poor.
Fighter pilots taking the controls of the B-2 say it made them feel like they
were "flying in a dumpster". A fine wire mesh was embedded in the windows to
block radar signals.
The two crew sat side-by-side on ACES II zero-zero (zero speed, zero
altitude) ejection seats, which blasted through frangible roof panels. The
"mission commander", who handled navigation and weapons delivery, sat on the
left, while the pilot sat on the right. The mission commander was also a
rated pilot, and could fly the aircraft if need be. They controlled the
aircraft via a "glass cockpit", with each crew using a dashboard featuring
four 15-centimeter (6-inch) color CRT multifunction displays (MFDs) and a
fighter-style control stick. There was provision for a third seat in case
the crew workload proved too high, but a third crewperson proved unnecessary.
A chemical toilet and rollup mattress could be carried for long missions. It
is unclear if other conveniences were provided, such as a small refrigerator
or microwave oven.
The B-2's original "Navigation Sub-System (NSS)" included a Kearfott Inertial
Management Unit and a Northrop NAS-26 "Astro-Inertial Unit (AIU)", which
obtained position fixes using a telescope to lock on to star positions, using
a noticeable port on top of the wing off to the left side of the cockpit. It
even worked in daylight when the bomber was at high altitude; it was a
descendant of an AIU developed for the SR-71.
The B-2 was fitted with AN/APQ-181 radar, with some similarities to the
AN/APG-70 used on the F-15E Strike Eagle fighter. The AN/APQ-181 was a
Ku-band (high microwave, from 12 GHz / 3 centimeters to 18 GHz / 2
centimeters) radar, with an electronically steered antenna in the lower
leading edge of each wing. The Ku band suffers from greater atmospheric
attenuation than lower frequency bands, but it also provides very high
resolution for navigation and targeting. The AN/APQ-181 provided LPI
operation and 20 modes, including:
- A "Synthetic Aperture Radar (SAR)" mode for ground mapping, with a "Ground
Moving Target Indicator (GMTI)" capability.
- A "Terrain Following / Terrain Avoidance (TF/TA)" mode for low-level
flight.
- A mode for tanker rendezvous.
- Weather mapping and navigation modes.
Finally, the B-2 included a countermeasures suite, the "Defensive Management
System (DMS)", the details of which were generally secret. All the avionics
systems were controlled by a total of 13 radiation-hardened "Avionics Control
Units (ACUs)" -- run by sophisticated software to help reduce flight load and
provide cockpit data display to enhance the crew's "situational awareness".
* After getting up to speed on the B-2, aircrew found the big bomber a very
pleasant ride and easy to fly. Its FBW system offloaded a good deal of the
work -- and, again, a flying wing is about as aerodynamically clean an
aircraft design as could be conceived. The B-2 was an aircraft that wanted
to get into the air but didn't want to come back down, and so pilots had to
use steep carrier-style landings. Apparently this caused some problems when
they went back to more conventional aircraft, and ended up making excessively
hard landings.
The aerodynamic cleanliness of the B-2 also made it very responsive to
throttle
changes. Midair refueling took a little practice, since once the B-2
got into the slipstream of the tanker, the bomber tended to slide forward a
bit. The B-2 was very stable, and by the other side of the same coin not
particularly maneuverable. B-52 aircrew moving up to the B-2 found ind it
more agile than the "Buff", but B-1B aircrew felt the "Bone" was superior in
this respect, like a very big fighter, and with its higher wing loading, the
B-1B also provided a smoother low-level ride than the B-2. The B-2s systems
were complicated and required extensive training to master, but aircrew who
grew up on computer games found the systems aspect fun, and no monster to
deal
with.
Although the official name assigned to the B-2 was "Spirit", the aircrews
didn't call it that; apparently it never acquired any particular nickname.
However, all the operational B-2s were given SPIRIT OF names, such as SPIRIT
OF TEXAS, SPIRIT OF KANSAS, SPIRIT OF CALIFORNIA, and so on. Only one wasn't
given a US state in the name: number 82-1066 was, appropriately, named
SPIRIT OF HASTINGS. All were based at Whiteman AFB with the USAF 509th Bomb
Wing, where they remain today.
BACK_TO_TOP
* As mentioned, the Air Force originally planned a total of 132 B-2 bombers
as the airborne leg of the nuclear "triad" of bombers, land-based missiles,
and submarine-launch missiles that comprise America's nuclear deterrent. In
reality, the end of the Cold War meant that the need for new strategic
weapons systems had greatly diminished. In addition, the B-2 was a highly
advanced aircraft, leading to program glitches, cost escalations, schedule
stretchouts, furious political controversies, and repeated cuts in production
numbers.
Although the Air Force had accepted the first B-2 in late 1993, the B-2
remained in service test for several more years, not reaching formal initial
operational capability until 1997. The USAF only obtained a total of 20
production aircraft. The small production buy meant that the high
development costs were spread over a handful of aircraft, and since the
program costs were about $48 billion USD, that came to about $2.4 billion USD
per aircraft. Had more B-2s been built, of course their incremental cost
would have been much less, though still clearly in the hundreds of millions
of dollars.
The first ten B-2s delivered to the Air Force, from December 1993 to late
1995, were "Block 10" machines, intended for service evaluation and training.
They couldn't fly at full flight loads, lacked precision weapons guidance and
terrain following capability, and had a limited DMS. Eight "Block 20"
machines were delivered in 1996 and 1997, which were up to operational
specification, along with some improvements such as a Global Positioning
System (GPS) satellite navigation receiver. The GPS receiver system was
integrated into a "GPS-Aided Targeting System (GATS)" to support the GAM
GPS-guided bomb, and later the JDAM and other GPS-guided weapons. The ten
Block 10s were brought up to Block 20 specification.
The Block 20s were followed by two final new-build "Block 30" aircraft, with
the older service machines brought up to the same specification; the AV/1
prototype was also later brought up to Block 30 spec, for a fleet of 21
machines. The Block 30s had avionics improvements, including a satellite
communications (SATCOM) link; the lidar contrail-detection system; support
for new GPS-guided weapons; and in particular, substantial modifications
to improve their stealthiness.
Adding the new stealth features required stripping off all the aircraft's
paint and RAM and performing some airframe changes. Stripping off the
aircraft's surface layers was tricky, since it had to be done without
damaging the composite skin, or resulting in massive amounts of toxic
solvents that would be a pain to dispose of properly. Northrop Grumman came
up with a scheme in which the aircraft was air-blasted with crystallized
wheat starch, a substance that resembles granulated sugar. The starch proved
able to remove coatings without damaging the composite skin. Not only was
disposal of the starch relatively straightforward, it could be re-used about
ten times; in fact, it became more effective after three or four cycles.
* The B-2 went into combat for the first time on the night of 24 March 1999,
at the very start of Operation ALLIED FORCE, the NATO air campaign against
Serbia. The B-2 dropped JDAM GPS-guided bombs in the opening phases of the
campaign to cripple Serbian air defenses so that conventional strike aircraft
could operate with greater safety. The B-2 continued to fly strikes against
well-defended targets during the rest of the campaign, unfortunately
acquiring a bit of notoriety on 7 May 1999 when a B-2 dropped JDAMs on the
Chinese embassy in Belgrade. The Chinese government protested loudly and
angrily. The blunder was due to bad intelligence and mission planning, not a
technical failure or crew error.
Six B-2s were committed to Operation ENDURING FREEDOM, the American
intervention in Afghanistan in 2001:2002, performing strikes in the early
phases of the conflict. One mission lasted 44 hours, the longest combat
sortie in the history of air warfare, with B-2s flying out of Whiteman to
Afghanistan, dropping their loads, and then landing on Diego Garcia island in
the Indian Ocean to refuel, rearm, and take on new crews while the engines
remained on idle. This done, the B-2s went back to Afghanistan to drop their
loads, and finally returned to Whiteman. Four B-2s were also committed to
Operation IRAQI FREEDOM, the American invasion of Iraq in the spring of 2003.
The first B-2 to be lost was the SPIRIT OF KANSAS, which suffered a take-off
accident at Andersen AFB on Guam on 23 February 2008. The two crew were able
to eject safely. The particular aircraft had been built in 1989 and had
almost 5,200 flight hours on it.
In the meantime, the bomber has continued to be refined. An improved
coating scheme, which provided an overall coating of RAM, was developed after
the introduction of the Block 30. The new coating scheme not only reduced
RCS, but reduced maintenance time per flight hour from 20.8 hours to 9.2
hours. The old scheme used caulk and tape to seal off the radar-reflective
edges of access panels. That was not only labor-intensive, but the tape
tended to strip off in flight. The improved scheme did not seal off the
edges; the RAM coating absorbed RF energy that penetrated into cracks. There
has been work on further improved coatings.
Along with the improved coatings, the B-2 has also received new bomb racks
that allow it to carry up to 80 GPS-guided weapons of up to 225 kilograms
(500 pounds) each -- with a follow-on effort permitting carriage of 40 such
munitions, plus four 2,250-kilogram (5,000-pound) GBU-28 "bunker-buster"
munitions.
In a particularly significant upgrade, in the summer of 2004, the Air Force
awarded a contract under the "Radar Modernization Program (RMP)" for the
development of a modernized radar system for the B-2, based on "active
electronically scanned array (AESA)" technology. An AESA features an antenna
made up of a grid of smart transmit-receive elements that can cooperate to
perform functions or perform multiple functions in parallel. There were
delays in the program, but the first upgraded B-2 with the new radar went
back into service in 2009, with the program completed in 2012.
The new B-2 radar resolved conflicts that existed between the bomber's radar
and commercial systems, and allowed the bomber to communicate and exchange
target data with other platforms. Maintenance was reduced as well, partly
because of the elimination of moving parts. The B-2's defensive management
system and radar transponder were also updated as part of the effort.
New stores have been qualified, particularly the little 125-kilogram
(250-pound) winged "Small Diameter Bomb II (SDB II)", and the huge
13,100-kilogram (28,900-pound) "Massive Ordnance Penetrator (MOP)" GPS-guided
bunker-buster, with the B-2 to carry two MOPs. Other improvements that have
been performed, are being implemented, or are planned include:
- A new high-bandwidth "beyond line of sight (BLOS)" communications system
to replace current radios and the satcom system. There is also work on a
"Very Low Frequency / Low Frequency (VLF/LF)" communications system to
allow the B-2 to hook into the communications system used by America's
ballistic-missile submarines, and other strategic assets.
- A Link 16 Multifunction Information Datalink System (MIDS).
- Fix of an aft-deck cracking problem, caused by vibration around the buried
engine exhausts, that afflicts a number of B-2s.
- Computer upgrades, both to eliminate old systems for which parts are no
longer available, and to provide more processing power. The improved
processing power will permit new software that can increase the capability
of the bomber's offensive and defensive avionics systems, as well as
permit mixed loads of stores, which the B-2 handles poorly at present.
- A fiber-optic databus system to provide greater throughput and resistance
to electromagnetic interference.
- A new digital cockpit layout, with color active-matrix LCD flat panels to
replace the CRT-based MFDs. Flight management computers are also to be
updated.
- A new Mode 5/S IFF system -- it appears partly implemented to allow a B-2
to fly in controlled airspace.
- Upgrades to the F118 engines to provide them with "full authority digital
engine control (FADEC)" and an improved fan section, intended to extend
engine life and to increase resistance to "foreign object damage" caused
by ice buildup in the serpentine inlets.
- A "Defensive Management System Modernization (DMS-M)" effort, to
comprehensively update the B-2's elderly defensive countermeasures system.
Along with defensive countermeasures, the DMS-M will effectively operate
as an electronic intelligence system to characterize the electronic
battlespace, with the intelligence distributed to other platforms via
datalink.
Of the 20 B-2s currently in service, one is dedicated to tests and trials;
typically, about a dozen machines are available for operations. On 18
January 2016, the B-2 returned to war, with two B-2s flying from Whiteman AFB
to bomb Islamic State terrorist training camps in Libya, plastering them with
108 225-kilogram JDAMs. The mission took 34 hours, and involved at least
five mid-air refuelings. The operating cost of the B-2 is definitely high,
so there was some puzzlement as to why the USAF didn't use less expensive
bombers like the B-52. There were speculations that the use of the B-2 was
as a show of force capability to impress other players, though there were
replies that the B-2 could have really been the best aircraft for the mission
-- for example, being able to carry far more JDAMs than a B-52.
The Air Force is working on a replacement, the "B-21 Raider", originally the
"Long Range Strike Bomber (LRS-B)", to be built by Northrop Grumman. It
was first unveiled to the public in late 2022, revealing an aircraft very
similar to the B-2, but clearly differing in details -- most significantly,
the rear being in a simpler "W" configuration. It will be somewhat smaller,
more reconfigurable, and cheaper to buy and fly. It will leverage off
operational experience with the B-2, a Northrop Grumman official saying:
"What we've learned on B-2 are finding themselves baselined in the design for
B-21 for supportability, sustainability, [and] mission capable rate."
The B-21 will go into service no earlier than 2026, with at least 100 to be
obtained, and possibly twice that many. The B-2 is currently scheduled to be
out of service by 2032, though that date is obviously subject to change.
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* In 1994, the Planes of Fame air museum in Chino, California, restored to
flight status the N-9M, one of Jack Northrop's single-seat experimental
flying wing prototypes. In February 1995, it flew to Edwards AFB to
commemorate the 50th anniversary of its first flight in 1945 by being
photographed next to a B-2. B-2 test pilot Bruce Hinds used the opportunity
to take the N-9M out for a spin.
I saw a B-2 in flight for the first time at an airshow in Denver in the
spring of 2007. That fall, I was on a road trip from Colorado to Florida and
made a stop at a zoo near Salina, Kansas. While I was going into the zoo, I
saw a sci-fi-looking aircraft near the horizon. I got a zoom shot of it with
my camera to confirm that it was a B-2. I was a bit surprised to see it
there, but as I drove into Missouri, I went past Whiteman AFB and made the
connection.
* Sources include:
- "'Green' Paint Stripper Preserves B-2 Lines" by William B. Scott, AVIATION
WEEK, 16 December 1996, 75:76.
- "B-2 Stealth Bomber" by Bill Sweetman, WORLD AIR POWER JOURNAL, Volume
31 / Winter 1997, 46:95.
- "Secret Spaces On B-2 May Carry New Jammer" by David A. Fulghum & Robert
Wall, AVIATION WEEK, 20 November 2000, 51.
- "New Stealth Coatings Boost B-2 Performance" by David A. Fulghum & Robert
Wall, AVIATION WEEK, 20 November 2000, 53:54.
- "A Work In Progress" by Robert Wall, AVIATION WEEK, 5 January 2004, 31:32.
- "First Fall Of A B-2" by David A. Fulghum & Amy Butler, AVIATION WEEK, 3
March 2008, 32.
- "Born-Again Bomber" by Guy Norris, AVIATION WEEK, 3 August 2009, 46:47.
* Illustrations details:
- BANNER: F-117s in formation / USAF
- TACIT BLUE / USAF Museum
- B-2 Stealth Bomber / USAF
- B-2 Stealth Bomber landing at Whiteman after Iraq strikes / USAF, MSGT
Francis Dupuis
- B-2 Stealth Bomber tanks up / USAF, TSGT Shane Cuomo
- B-2 Stealth Bomber / RAF Fairford UK / 2019 / Steve Lynes / Creative
Commons Share Alike License
- B-2 with F-117s / USAF
* Revision history:
v1.0.0 / 01 dec 03
v1.0.1 / 01 oct 05 / Review & polish.
v1.0.2 / 01 sep 07 / Review & polish.
v1.0.3 / 01 apr 08 / Added crash of SPIRIT OF KANSAS.
v1.0.4 / 01 mar 10 / Review & polish.
v1.0.5 / 01 feb 12 / Review & polish.
v1.0.6 / 01 jan 14 / Review & polish.
v1.0.7 / 01 dec 15 / Review & polish.
v1.0.8 / 01 nov 17 / Review & polish.
v1.0.9 / 01 oct 19 / Review, update, & polish.
v1.1.0 / 01 aug 21 / Review, update, & polish.
v1.1.1 / 01 aug 23 / Review, update, & polish. (*)
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