December 23 / B-1 Lancer first flight
Rockwell B-1 Lancer
B-1B arriving for NATO and Czech Air Force days in 2017
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 with the B-2 Spirit and the B-52 Stratofortress as of 2022.
The B-1 was first envisioned in the 1960s as a platform that would combine the Mach 2 speed of the B-58 Hustler with the range and payload of the B-52, and was meant to ultimately replace both bombers. After a long series of studies, Rockwell International (now part of Boeing) won the design contest for what emerged as the B-1A. This version had a top speed of Mach 2.2 at high altitudes and the capability of flying for long distances at Mach 0.85 at very low altitudes. The combination of the high cost of the aircraft, the introduction of the AGM-86 cruise missile that flew the same basic speed and distance, and early work on the stealth bomber all significantly reduced the need for the B-1. This led to the program being cancelled in 1977 after the B-1A prototypes had been built.
The program was restarted in 1981, largely as an interim measure due to delays in the B-2 stealth bomber program. This led to a redesign as the B-1B, which differed from the B-1A by having a lower top speed of Mach 1.25 at high altitude, but improved the low-altitude speed to Mach 0.96. The electronics were also extensively improved, and the airframe was improved to allow takeoff with the maximum possible fuel and weapons load. Deliveries of the B-1B began in 1986 and formally entered service with Strategic Air Command (SAC) as a nuclear bomber that same year. By 1988, all 100 aircraft had been delivered.
With the disestablishment of SAC and its reassignment to the Air Combat Command in 1992, the B-1B was converted to a conventional bombing role. It first served in combat during Operation Desert Fox in 1998 and again during the NATO action in Kosovo the following year. The B-1B has supported U.S. and NATO military forces in Afghanistan and Iraq. As of 2021, the Air Force has an inventory of 45 B-1Bs. The Northrop Grumman B-21 Raider is to begin replacing the B-1B after 2025; all B-1s are planned to be retired by 2036.
Rear view of a B-1B in flight at the Radom Airshow 2017
A B-1B with wings swept full forward
Design
Overview
The B-1 has a blended wing body configuration, with a variable-sweep wing, four turbofan engines, triangular ride-control fins and a cruciform tail. The wings can sweep from 15 degrees to 67.5 degrees (full forward to full sweep). Forward-swept wing settings are used for takeoff, landings and high-altitude economical cruise. Aft-swept wing settings are used in high subsonic and supersonic flight. The B-1's variable-sweep wings and thrust-to-weight ratio provide it with improved takeoff performance, allowing it to use shorter runways than previous bombers. The length of the aircraft presented a flexing problem due to air turbulence at low altitudes. To alleviate this, Rockwell included small triangular fin control surfaces or vanes near the nose on the B-1. The B-1's Structural Mode Control System moves the vanes, and lower rudder, to counteract the effects of turbulence and smooth out the ride.
Unlike the B-1A, the B-1B cannot reach Mach 2+ speeds; its maximum speed is Mach 1.25 (about 950 mph or 1,530 km/h at altitude), but its low-level speed increased to Mach 0.92 (700 mph, 1,130 km/h). The speed of the current version of the aircraft is limited by the need to avoid damage to its structure and air intakes. To help lower its RCS, the B-1B uses serpentine air intake ducts and fixed intake ramps, which limit its speed compared to the B-1A. Vanes in the intake ducts serve to deflect and shield radar returns from the highly reflective engine compressor blades.
The B-1A's engine was modified slightly to produce the GE F101-102 for the B-1B, with an emphasis on durability, and increased efficiency. The core from this engine was subsequently used in several other engines, including the GE F110 used in the F-14 Tomcat, F-15K/SG variants and later versions of the General Dynamics F-16 Fighting Falcon. It is also the basis for the non-afterburning GE F118 used in the B-2 Spirit and the U-2S. The F101 engine core is also used in the CFM56 civil engine.
The nose-gear door is the location for ground-crew control of the auxiliary power unit (APU) which can be used during a scramble for quick-starting the APU.
B-1B alongside the B-52H
A B-1B cockpit at night
Avionics
The B-1's main computer is the IBM AP-101, which was also used on the Space Shuttle orbiter and the B-52 bomber. The computer is programmed with the JOVIAL programming language. The Lancer's offensive avionics include the Westinghouse (now Northrop Grumman) AN/APQ-164 forward-looking offensive passive electronically scanned array radar set with electronic beam steering (and a fixed antenna pointed downward for reduced radar observability), synthetic aperture radar, ground moving target indication (GMTI), and terrain-following radar modes, Doppler navigation, radar altimeter, and an inertial navigation suite. The B-1B Block D upgrade added a Global Positioning System (GPS) receiver beginning in 1995.
The B-1's defensive electronics include the Eaton AN/ALQ-161A radar warning and defensive jamming equipment, which has three sets of antennas; one at the front base of each wing and the third rear-facing in the tail radome. Also in the tail radome is the AN/ALQ-153 missile approach warning system (pulse-Doppler radar). The ALQ-161 is linked to a total of eight AN/ALE-49 flare dispensers located on top behind the canopy, which is handled by the AN/ASQ-184 avionics management system. Each AN/ALE-49 dispenser has a capacity of 12 MJU-23A/B flares. The MJU-23A/B flare is one of the world's largest infrared countermeasure flares at a weight of over 3.3 pounds (1.5 kg). The B-1 has also been equipped to carry the ALE-50 towed decoy system.
Also aiding the B-1's survivability is its relatively low RCS. Although not technically a stealth aircraft, thanks to the aircraft's structure, serpentine intake paths and use of radar-absorbent material its RCS is about 1/50th that of the similar-sized B-52. This is approximately 26 ft2 or 2.4 m2, comparable to that of a small fighter aircraft.
The B-1 holds 61 FAI world records for speed, payload, distance, and time-to-climb in different aircraft weight classes. In November 1993, three B-1Bs set a long-distance record for the aircraft, which demonstrated its ability to conduct extended mission lengths to strike anywhere in the world and return to base without any stops. The National Aeronautic Association recognized the B-1B for completing one of the 10 most memorable record flights for 1994.
A B-1B banking during a demonstration in 2004
A B-1B on public display at Ellsworth AFB, 2003
Upgrades
The B-1 has been upgraded since production, beginning with the "Conventional Mission Upgrade Program" (CMUP), which added a new MIL-STD-1760 smart-weapons interface to enable the use of precision-guided conventional weapons. CMUP was delivered through a series of upgrades:
Block A was the standard B-1B with the capability to deliver non-precision gravity bombs.
Block B brought an improved Synthetic Aperture Radar, and upgrades to the Defensive Countermeasures System and was fielded in 1995.
Block C provided an "enhanced capability" for delivery of up to 30 cluster bomb units (CBUs) per sortie with modifications made to 50 bomb racks.
Block D added a "Near Precision Capability" via improved weapons and targeting systems, and added advanced secure communications capabilities. The first part of the electronic countermeasures upgrade added Joint Direct Attack Munition (JDAM), ALE-50 towed decoy system and anti-jam radios.
Block E upgraded the avionics computers and incorporated the Wind Corrected Munitions Dispenser (WCMD), the AGM-154 Joint Standoff Weapon (JSOW) and the AGM-158 JASSM (Joint Air to Surface Standoff Munition), substantially improving the bomber's capability. Upgrades were completed in September 2006.
Block F was the Defensive Systems Upgrade Program (DSUP) to improve the aircraft's electronic countermeasures and jamming capabilities, but it was cancelled in December 2002 due to cost overruns and delays.
In 2007, the Sniper XR targeting pod was integrated into the B-1 fleet. The pod is mounted on an external hardpoint at the aircraft's chin near the forward bomb bay. Following accelerated testing, the Sniper pod was fielded in the summer of 2008. Future precision munitions include the Small Diameter Bomb.
The USAF commenced the Integrated Battle Station (IBS) modification in 2012 as a combination of three separate upgrades when it realised the benefits of completing them concurrently; the Fully Integrated Data Link (FIDL), Vertical Situational Display Unit (ASDU) and Central Integrated Test System (CITS). FIDL enables electronic data sharing, eliminating the need to enter information between systems by hand. VSDU replaces existing flight instruments with multifunction colour displays, a second display aids with threat evasion and targeting, and acts as a backup display. CITS saw a new diagnostic system installed that allows the crew to monitor over 9,000 parameters on the aircraft. Other additions are to replace the two spinning mass gyroscopic inertial navigation system with ring laser gyroscopic systems and a GPS antenna, replacement of the APQ-164 radar with the Scalable Agile Beam Radar – Global Strike (SABR-GS) active electronically scanned array and a new attitude indicator. The IBS upgrades were completed in 2020.
In August 2019, the Air Force unveiled a modification to the B-1B to allow it to carry more weapons internally and externally. Using the moveable forward bulkhead, space in the intermediate bay was increased from 180 to 269 in (457 to 683 cm). Expanding the internal bay to make use of the Common Strategic Rotary Launcher (CSRL), as well as utilizing six of the eight external hardpoints that had been previously out of use to keep in line with the New START Treaty, would increase the B-1B's weapon load from 24 to 40. The configuration also enables it to carry heavier weapons in the 5,000 lb (2,300 kg) range, such as hypersonic missiles; the AGM-183 ARRW is planned for integration into the bomber. In the future, the HAWC could be used by the bomber which, combining both internal and external weapon carriage, could conceivably bring the total number of hypersonic weapons to 31.
A B-1B arrives at Royal International Air Tattoo 2008