TITLE:

NORTHROP GRUMMAN B-2 'Spirit'

TYPE:

Low-observable strategic penetration bomber.

PROGRAMME:

Development of high-level bomber started 1978; contract placed by USAF Aeronautical Systems Division October 1981; design modified for low-altitude operation 1983; KC-135 testbed for B-2 avionics flying at Edwards AFB since January 1987; six B-2s assigned to trials; all but first will be refurbished for operational service; two static airframes also funded, of which structural test airframe exceeded ultimate (150 per cent) load test before fracture at 161 per cent, December 1992; by 1995, durability test airframe had completed second simulated lifetime of 20,000 hours/30 years; 4,000 hour test programme planned, of which 26 per cent concerned with low observables (LO); testing ends 1997.

Boeing completed work with delivery of outboard wing sections for 21st aircraft on 3 May 1994 and then began storage of tooling. Vought followed suit shortly after with completion of final intermediate section. However, follow-on procurement not ruled out, with Northrop Grumman submitting cost estimates to USAF for additional 20 B-2As, pending outcome of force requirement study presented to Congress at beginning of May 1995; study cost $125 million, including funds to preserve B-2 manufacturing facilities for 12 months. Subsequent Congress decision to add $493 million to FY96 budget for start of procurement of follow-on batch of 20 eventually overruled by Clinton administration, with this appropriation instead being used to accelerate planned upgrade programme for existing aircraft and also to refurbish AV-1 to full production standard.

Conventional warfare capability is being expanded with the Northrop Grumman design, development, test and integration of the GPS-Aided Targeting System/GPS-Aided Munition (GATS/GAM) package into the B-2 fleet. GATS, which includes upgrading of the radar subsystem and weapons control software, will give Block 20 B-2As near-precision conventional weapons delivery capability. The first Block 20 B-2A is due to be handed over to the 509th Bomb Wing in June 1996 and a total of 128 GAM 2000 lb weapons will be delivered in 1996 to meet operational requirements, with each B-2 able to carry a maximum of 16 GAMs. Three GAM weapon tests undertaken from B-2s have explored extended down-range, short-range and cross-range footprints and full system-level GATS/GAM end-to-end testing commenced in the fourth quarter of 1995. To date, all tests have successfully demonstrated the B-2's ability to achieve a 6 m (20 ft) circular error of probability (CEP) requirement, with first release of GAM from B-2A taking place on 13 June 1995. Ultimately, GAM to be replaced by Joint Direct Attack Munition (JDAM). Production JDAM scheduled for release to service in 1999 and is key element in USAF proposals to use B-2A for long-range conventional bombing missions.

DESIGN FEATURES:

Blended flying wing, with straight leading-edges, swept at 33o; centre and tip sections have sharp, strongly under-cambered fixed leading-edges; two dielectric panels underwing outboard of flight deck cover dual radar antennae; 'double-W' trailing-edge incorporating elevons and drag rudders outboard of engines; two side by side weapons bays in lower centrebody each have small, drop-down spoiler panels ahead of doors, generating vortexes to ensure clean weapon release; engines fed by S-shaped air ducts; irregular-shaped air intakes feed engines, with three-pointed splitter plates ahead of inlets which remove boundary layer and provide secondary air flow for cooling and IR emissions control; upper lip of intake has single point; two auxiliary air inlet doors mounted on top of intake trunks remain open on ground and in slow-speed flight; two V-shaped overwing exhausts set well forward of trailing-edge; titanium on wing surface behind engine outlet; wingtips and leading-edges have dielectric covering of aerofoil section to mask radar-dissipating sawtooth construction.

Total 80,000 hours of testing aircraft's components include 24,000 hours wind tunnel tests, 44,000 hours avionics testing and 6,000 hours full-scale 'plastic bird' control system tests; flight testing to total 4,000 hours with six aircraft; all locations in airframe stored in CAD/CAM three-dimensional database used for machine tool, robot and tooling reference; prototype built on production tooling to accuracy of +-6.3 mm ({1/4} in) from tip to tip; nearly 900 new materials and processes developed; currently over 4,000 subcontractors throughout USA.

LANDING GEAR:

Tricycle type, adapted from Boeing 757/767. Inward-retracting four-wheel main bogies have large trapezoidal door of thick cross-section. Rearward-retracting two-wheel nose unit has small door with sawtooth edges and large rear door, also used for crew access. Two landing lights on nosewheel leg. Landing gear limiting speed 224 knots (415 km/h; 258 mph).

POWER PLANT:

Four 77.0 kN (17,300 lb st) General Electric F118-GE-100 non-afterburning turbofans mounted in pairs within wing structure, each side of weapons bay. In-flight refuelling receptacle in centrebody spine. Initially fuelled by JP-4; conversion to JP-8 due by March 1996. Development of contrail management system due by December 1996, reportedly involving regulation of exhaust temperatures, rather than mixing chloro-fluoro-sulfonic acid with exhaust gases, as previously understood.

ACCOMMODATION:

Two crew, with upward-firing ejection seats: pilot to port, mission commander/instructor pilot to starboard. Provision for third member. Both forward positions have conventional control columns. Flight, engine, sensor and systems information presented on nine-tube EFIS display. Either crew member capable of flying complete mission, although data entry panels biased towards weapon systems officer on starboard seat. Four flight deck windows.

SYSTEMS:

Hydraulic system for flying controls operates at 276 bars (4,000 lb/sq in). AlliedSignal APU outboard of port engine bay, covered by triangular door flush with wing surface.

AVIONICS:

Comms: Rockwell Collins VLF/LF receiver; ICS-150X intercom; Milstar satellite communications from Block 30.

Radar: Hughes AN/APQ-181 low-probability-of-intercept (LPI) J-band covert strike radar, having 21 modes including terrain-following and terrain-avoidance.

Flight: Rockwell Collins TCN-250 Tacan and VIR-130A ILS.

Instrumentation: Hughes GPS-Aided Targeting System (GATS) from Block 20, involving synthetic aperture mode on radar to establish GPS positional error of target for accurate high-level bombing; 4x zoom magnification available on radar picture.

Mission: Unspecified, but crew workload eased by three-position selector switch in cockpit to activate/deactivate appropriate equipment for 'take-off' (transfer mission data tape, checklist and appropriate flight controls mode), 'go to war' (flight controls in stealthy mode, weapons ready and radio emitters switched off) and 'land' (reactivate systems and perform checklist).

Self-defence: Loral Federal Systems AN/APR-50 RWR; Northrop Grumman ZSR-63 defensive aids equipment (role unspecified but reportedly involves active cancellation of radar returns).

ARMAMENT:

Boeing rotary launcher assembly (RLA) in each of two side by side weapons bays in lower centrebody; detachable for loading at weapons dump with up to eight large stores each. Total capacity of 16 AGM-129 ACMs. Alternative weapons include 16 B61 tactical/strategic or 16 B83 strategic free-fall nuclear bombs; 80 Mk 82 500 lb bombs; 16 Joint Direct Attack Munitions; 16 Mk 84 2,000 lb bombs; 36 M117 750 lb fire bombs; 36 CBU-87/89/97/98 cluster bombs; and 80 Mk 36 560 lb or Mk 62 sea mines. Stores of 1,000 lb and below held in four (two per weapons bay) bomb rack assemblies (BRA).

DIMENSIONS EXTERNAL:

Wing span: 52.43 m (172 ft 0 in)

Length overall: 21.03 m (69 ft 0 in)

Height overall: 18 m (17 ft 0 in)

AREAS (estimated):

Lower surface: over 464.5 m{2} (5,000 sq ft)

WEIGHTS AND LOADINGS:

Weight empty: 45,360-49,900 kg (100,000-110,000 lb)

Max weapon load: 18,144 kg (40,000 lb)

Max internal fuel capacity: 81,650-90,720 kg

(180,000-200,000 lb)

Normal T-O weight: 152,635 kg (336,500 lb)

Max T-O weight: 170,550 kg (376,000 lb)

PERFORMANCE:

Approach speed: 140 kts (259 km/h; 161 mph)

Service ceiling: 15,240 m (50,000 ft)

Range with one aerial refuelling:

over 10,000 n miles (18,520 km; 11,508 miles)

LENGTH (m) 21.03

HEIGHT (m) 5.18

WING SPAN (m) 52.43

MAX T-O WEIGHT (kg) 170550

MAX WING LOAD (kg/m{2}) 367.2

MAX RANGE (nm) 6300

SERVICE CEILING (m) 15240