Overall review on B2 history and aerodynamical characteristics

1. Aero Dynamic
Northrop Grumman :B2-Spirit
Travail réalisé par :
Khalil Mouallem (210661)
Responsable de projet
Docteur Bassam RIACHI
Ecole Supérieure d’Ingénieurs de Beyrouth

2. Université Saint-Joseph de Beyrouth
Contents
Northrop Grumman :B2-Spirit........................................................................................................ 1
Table de figures............................................................................................................................... 2
I. Remerciements :...................................................................................................................... 3
II. Introduction ............................................................................................................................ 3
III. Design and Specifications ....................................................................................................... 5
IV. Modifications and Upgrades................................................................................................... 9
V. Flight Hours and Missions..................................................................................................... 13
VI. How the spirits are chosen ................................................................................................ 14
VII. The future generations: ..................................................................................................... 15
VIII. Reference: .......................................................................................................................... 16
Table de figures
Figure 1:Shape of B2-Spirit from 3 views........................................................................................ 6
Figure 2:CL/CD vs AoA graph........................................................................................................... 7
Figure 3: Armament load of B2-Spirit ............................................................................................. 8
Figure 4: F118-GE-100 Turbofan( General Electric.......................................................................... 9
Figure 5:Radar deflection.............................................................................................................. 10
Figure 6:Cockpit of B2 ................................................................................................................... 12
Figure 7:B2-Spirit parts external and internal............................................................................... 13
Figure 8:The B21-Raider................................................................................................................ 16

3. I. Remerciements :
Je tiens à remercier Monsieur Bassam RIACHI pour son excellente méthode
pédagogique qui a permis de rendre ce cours captivant, stimulant et enrichissant
pour l'ensemble des étudiants créant ainsi un environnement d'apprentissage
stimulant et convivial. Je suis reconnaissant pour sa capacité à rendre des
concepts complexes plus accessibles et compréhensibles pour les étudiants,
grâce à des exemples concrets et des explications claires et précises. Enfin, je suis
reconnaissant pour son engagement constant qui a aidé chaque étudiant à
atteindre son plein potentiel.
II. Introduction
Jack Northrop first imagined the flying wing design 80 years ago in his garage.
From the Avion Experimental #1 in 1929, to the flying wing designs of the 1940’s
such as the N-M9 Flying Wing, XP-79B Flying Ram, XB-35, YB-49, and the YB-35, it
is easy to see how Jack’s legacy inspired the B-2 Spirit.
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

4. 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 Aug. 22, 1980, the Carter administration publicly
disclosed that the United States Department of Defense was working to develop
stealth aircraft, including a bomber.
The Advanced Technology Bomber (ATB) program began in 1979.
Full development of the black project followed and was funded under the code
name “Aurora.” After the evaluations of the companies’ proposals, the ATB
competition was narrowed to the Northrop/Boeing 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 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, which bore considerable similarities to the final design. The Air Force
originally planned to procure 165 of the ATB bombers.
The Northrop team’s ATB design was selected over the Lockheed/Rockwell design
on Oct. 20, 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 $1 billion to the
program’s cost. An estimated $23 billion was secretly spent for research and
development on the B-2 by 1989. MIT engineers and scientists helped assess the
mission effectiveness of the aircraft under a five-year classified contract during
the 1980s
Originally designed as a high-level penetrator able to steal into the Soviet Union
undetected and drop nuclear missiles, the Northrop Grumman B-2 Spirit has

5. evolved into a low-level weapon designed to destroy enemy warmaking potential
by the selective use of conventional precision-guided munitions.
Northrop Grumman teamed with Boeing, General Electric, and Hughes to achieve
the B-2. In doing so, it maximized the pool of talent available -- and minimized the
risk inherent in so advanced a program.
Shrouded in secrecy, Northrop built the B-2 at an old Ford Motor Company plant in
Pico Rivera, California. To avoid suspicion, the government set up many fake
companies to purchase components for the aircraft. Parts for the aircraft were
always delivered at night in unmarked trucks, and when military officers visited,
they never wore their uniforms. All the employees at the plant were sworn to
secrecy and had to undergo polygraph tests from time to time.
III. Design and Specifications
The cost to procure each B-2 was US$737 million in 1997 dollars (equivalent to
US$1173 million in 2021)based only on a fleet cost of US$15.48 billion.
The B-2 Spirit is a low-observable, strategic, long-range, heavy bomber capable of
penetrating sophisticated and dense air-defense shields. It is capable of all-
altitude attack missions up to 50,000ft, with a range of more than 6,000nm(=11
112KM) unrefueled and over 10,000nm(=18 520Km) with one refueling, giving it
the ability to fly to any point in the world within hours. Each hour of flight needs
119 hrs of maintenance

6. Figure 1:Shape of B2-Spirit from 3 views
1. Performance:
• Engine:4x 4 × General Electric F118-GE-100 Turbofan
• Power:17,300 pound-force
• Max Cruise Speed:550 knots or1,019 Km/h (M=0.95)high subsonic
• Approach Speed (Vref):
• Travel range: 6,000 Nautical Miles or 11,112 Kilometers
• Fuel Economy:0.24 nautical mile / gallon or 0.117 Km/ liter
• Service Ceiling: 50,000 feet
• Rate of Climb: 3000 feet / minute o15.24metre / second
• Take Off Distance :2039 meter - 6,689.55 feet
• Landing Distance: 1052 meter - 3,451.40 feet
2. Specifications:
• Thrust: 17,300 pounds each engine
Wingspan: 172 feet (52.12 meters)
Length: 69 feet (20.9 meters)
Height: 17 feet (5.1 meters)
Weight: 160,000 pounds (72,575 kilograms)

7. Maximum takeoff weight: 336,500 pounds (152,634 kilograms)
Fuel capacity: 167,000 pounds (75750 kilograms)
Payload: 40,000 pounds (18,144 kilograms)
Range: intercontinental
Ceiling: 50,000 feet (15,240 meters)
Crew: two pilots: pilot and mission commander
• Thrust/Weight ration: T/W =0.205
• Lift to Drag ratio : CL/CD max=19.5
Figure 2:CL/CD vs AoA graph
• Wing loading: 67.3 lb/ sq ft (329 kg/m2
)
3. Armament:
The bomber can drop conventional and thermonuclear weapons,such as up to
eighty 500-pound class (230 kg) Mk 82 JDAM GPS-guided bombs, or sixteen 2,400-
pound (1,100 kg) B83 nuclear bombs.
Two internal bays for ordnance and payload with an official limit of 40,000 lb
(18,000 kg); maximum estimated limit is 50,000 lb (23,000 kg)
• 80× 500 lb (230 kg) class bombs (Mk-82, GBU-38) mounted on Bomb
Rack Assembly (BRA)
• 36× 750 lb (340 kg) CBU class bombs on BRA
• 16× 2,000 lb (910 kg) class bombs (Mk-84, GBU-31) mounted on
Rotary Launcher Assembly (RLA)

8. • 16× B61 or B83 nuclear bombs on RLA (strategic mission)
• Standoff weapon: AGM-154 Joint Standoff Weapon (JSOW) and AGM-
158 Joint Air-to-Surface Standoff Missile (JASSM)
• 2× GBU-57 Massive Ordnance Penetrator
4. Engine:
Widespread characteristics:
• Type: Two Spool turbofan
• Length: 101 in (260 cm)
• Diameter: 46.5 in (118 cm)
• Dry weight: 3,200 lb. (1,500 kg)
Components:
• Compressor: Axial, one stage fan, two stage LP compressor, nine stage
HP compressor
• Combustors: Annular
• Turbine: one stage HP turbine, two stage LP turbine
Performance:
Figure 3: Armament load of B2-Spirit

9. • Maximum thrust: 19,000 lbf (85 kN)
• Overall pressure ratio: 35:1
• Thrust-to-weight ratio: 5.9:1
IV. Modifications and Upgrades
i. Radar
Most of the B-2 is made from a carbon-graphite composite material that is stronger than
steel, lighter than aluminum, and absorbs a significant amount of radar energy.
Figure 4: F118-GE-100 Turbofan( General Electric

10. The B-2 is assembled with unusually tight engineering tolerances 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. Each
B-2 is kept inside a climate-controlled hangar (Extra Large Deployable Aircraft Hangar
System) large enough to accommodate its 172-foot (52 m) wingspan.
The B-2 has a radar cross-section (RCS) of about 0.1 m2 (1.1 sq ft). The bomber does not
always fly stealthily when nearing air defenses pilots "stealth up" the B-2, except briefly
when the bomb bay opens.
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 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.
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
Figure 5:Radar deflection

11. Burying engines deep inside the fuselage also minimizes the thermal visibility or infrared
signature of the exhaust. At the engine intake, cold air from the boundary layer below the
main inlet enters the fuselage (boundary layer suction)and is mixed with hot exhaust air
just before the nozzles .
The resulting cooler air is conducted over a surface composed of heat resistant carbon-
fiber-reinforced polymer and titanium alloy elements, which disperse the air laterally, to
accelerate its cooling.
The B-2 lacks afterburners as the hot exhaust would increase the infrared signature;
breaking the sound barrier would produce an obvious sonic boom as well as aerodynamic
heating of the aircraft skin which would also increase the infrared signature.
Additional reduction in its radar signature was achieved using various radar-absorbent
materials (RAM) to absorb and neutralize radar beams.
ii. Technology and avionics
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 and Global
Positioning System (GPS) guidance, NAS-26 astro-inertial navigation system and a
Defensive Management System (DMS) to inform the flight crew of possible threats. The
DMS was upgraded in 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.
In November 2002, Raytheon was awarded a contract to develop a new Ku-band AESA
(active electronically scanned array) antenna for the B-2 radar to avoid interference with
commercial satellite systems after 2007. Flight tests with new radar began in October 2007
and continued until 2008. Installation of the new antenna on the B-2 fleet is to be
completed by 2012.
The B-2’s navigation suite includes a Rockwell Collins TCN-250 tactical air navigation
system (TACAN) and a VIR-130A instrument landing system.
The communications equipment is supplied by Rockwell Collins. A Milstar military
strategic and tactical relay satellite communications system is installed in block 30 aircraft.
The aircraft have been upgraded with Link 16 communications link.

12. 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 40 miles (64 km) away from thunderstorms, to avoid static
discharge and lightning strikes.
Figure 6:Cockpit of B2

13. iii. Aerodynamics
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 the elevons remain drooped during takeoff until a high enough airspeed has
been attained.
V. Flight Hours and Missions
In the 1990s, the first operational B-2 aircraft, named Spirit of Missouri, was delivered to
Whiteman Air Force Base, Missouri, on December 17, 1993. The B-2 achieved initial operational
Figure 7:B2-Spirit parts external and internal

14. capability (IOC) on January 1, 1997. Originally designed for nuclear weapons delivery, its modern
usage includes a flexible role with both conventional and nuclear capabilities.
The B-2 made its combat debut in the Kosovo War in 1999, where it played a significant role in
destroying 33% of selected Serbian bombing targets in the first eight weeks of U.S. involvement.
During this war, six B-2s flew non-stop to Yugoslavia from their home base in Missouri and back,
totaling 30 hours. The B-2 was the first aircraft to deploy GPS satellite-guided JDAM "smart
bombs" in combat use in Kosovo, effectively replacing the controversial tactic of carpet-bombing.
In the 2000s, the B-2 saw service in Afghanistan, striking ground targets in support of Operation
Enduring Freedom. B-2s would be stationed in the Middle East as 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. During the Iraq War, B-2s operated from Diego Garcia and an
undisclosed "forward operating location." As of September 2013, the longest combat mission had
been 44.3 hours.
In the 2010s, organizational changes led to the transfer of B-2s to the Air Force Global Strike
Command. Notable missions include the B-2s being the first U.S. aircraft into action in Operation
Odyssey Dawn in Libya in March 2011. In August 2011, there were considerations for a B-2
airstrike as an alternative in the U.S. Special Operations raid into Abbottabad, Pakistan, that
resulted in the death of Osama bin Laden. On January 18, 2017, two B-2s attacked an ISIS training
camp southwest of Sirte, Libya, flying a 33-hour round-trip mission from Whiteman Air Force
Base, Missouri, with multiple refueling during the trip.
VI. How the spirits are chosen .
Every B-2 pilot goes through Initial Qualification Training at Whiteman Air Force Base to learn how
to fly the most technologically advanced strategic bomber in the world. Once the IQT students
have gone through hundreds of hours of academics and training in the B-2 simulators, they are
finally able to put their skills to the test and take-off for their first flight. Following their first flight,
each pilot receives a Spirit Number, which cements their place in history. There are only 550 B-2
pilots who have been assigned a Spirit Number.

15. VII. The future generations:
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 intercontinental strategic bomber for the USAF,
able to deliver conventional and thermonuclear weapons. The Air Force intends the B-21 to
replace the Rockwell B-1 Lancer and Northrop Grumman B-2 Spirit by 2040, and possibly the
Boeing B-52 Stratofortress after that.
The Air Force began planning for the B-21 in 2011 and was awarded the major development
contract in 2015.The B-21 made its first flight on 10 November 2023. It is expected to enter service
by 2027.
Many aspects of the B-21 program are highly classified; the program is designated as a special
access program.
Northrop CEO Kathy Warden said that the B-21 is designed with modular, open systems
architecture to allow easy upgrades and, potentially, the ability to export components to foreign
buyers. Warden said that the B-21's internal operations were "extremely advanced compared to
the B-2" and that the B-21 was slightly smaller than the B-2, with a longer range.
The first prototype B-21 made its maiden flight on 10 November 2023

16. Figure 8:The B21-Raider
VIII. Reference:
I. Home | Northrop Grumman
II. Northrop Grumman B-2 Spirit - Wikipedia
III. F110 New Engine | GE Aerospace
IV. (PDF) Performance Analysis of B-2 Spirit (researchgate.net)
V. How the Air Force Catalogs Its B-2 Spirit Pilots - MilitarySpot.com
VI. This look inside the B-2 Bomber is so detailed it should be classified | We Are The
Mighty
VII. https://youtu.be/cG4cwo0BWMM?si=W4FUjSLB_QvO6EDC