Trump sends a very deadly message to North Korea in Military exercise. The Rockwell B-1 Lancer[N 1] is a supersonic variable-sweep wing, heavy bomber used by the United States Air Force (USAF). It is commonly called the "Bone" (from "B-One"). It is one of three strategic bombers in the USAF fleet as of 2017, the other two being the B-2 Spirit "Stealth Bomber", and the B-52 Stratofortress.
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, ultimately replacing both. 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 altitude 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 ALCM cruise missile that flew the same basic profile, and early work on the stealth bomber all significantly affected 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 while the stealth bomber entered service. This led to a redesign as the B-1B, which had lower top speed at high altitude of Mach 1.25, but improved low-altitude performance of Mach 0.96. The electronics were also extensively improved during the redesign, and the airframe was improved to allow takeoff with the maximum possible fuel and weapons load. The B-1B began deliveries in 1986 and formally entered service with Strategic Air Command (SAC) as a nuclear bomber in 1986. By 1988, all 100 aircraft had been delivered.
In the early 1990s, following the Gulf War and concurrent with the disestablishment of SAC and its reassignment to the newly formed Air Combat Command (ACC), the B-1B was converted to conventional bombing use. 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. The USAF had 66 B-1Bs in service as of September 2012. The B-1B is expected to continue to serve into the 2030s, with the Northrop Grumman B-21 Raider to begin replacing the B-1B after 2025. The B-1s currently in inventory will reach the end of their service lives by 2045.
The B-1 has a blended wing body configuration, with variable-sweep wing, four turbofan engines, triangular fin control surfaces and 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 maximum 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 altitude. 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 rotates the vanes automatically to counteract turbulence and smooth out the ride.
A rear view of a B-1B at Royal International Air Tattoo air show in 2004
Rear view of B-1B in flight, 2004
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 radar cross section (RCS), the B-1B uses serpentine air intake ducts (see S-duct) and fixed intake ramps, which limit its speed compared to the B-1A. Vanes in the intake ducts serve to deflect and shield radar emissions 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 of this engine has since been re-used in several other engine designs, including the GE F110 which has seen use in the F-14 Tomcat, F-15K/SG variants and most recent 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 was the basis for the core of the extremely popular CFM56 civil engine, which can be found on some versions of practically every small-to-medium-sized airliner. The nose gear cover door has controls for the auxiliary power units (APUs), which allow for quick starts of the APUs upon order to scramble.