The Boeing B-52 Stratofortress US Military Bomber is a long-range, subsonic, jet-powered, strategic bomber operated by the United States Air Force (USAF) since 1955.
Beginning with the successful contract bid on 5 June 1946, the Boeing B-52 Stratofortress US Military Bomber went through several design steps; from a straight wing aircraft powered by six turboprop engines to the final prototype YB-52, with eight turbojet engines. The aircraft made its first flight on 15 April 1952 with "Tex" Johnston as pilot.
Built to carry nuclear weapons for Cold War-era deterrence missions, the B-52 Stratofortress replaced the Convair B-36. Although a veteran of a number of wars, the Stratofortress has dropped only conventional munitions in actual combat. The B-52 carries up to 70,000 pounds (32,000 kg) of weapons.
The United States Air Force (USAF) has had B-52s in active service since 1955, initially with the Strategic Air Command (SAC), with all aircraft later absorbed into the Air Combat Command (ACC) following SAC's disestablishment in 1992. Superior performance at high subsonic speeds and relatively low operating costs have kept the B-52 in service despite proposals to replace it with the Mach 3 XB-70 Valkyrie, supersonic B-1B Lancer and stealthy B-2 Spirit. In January 2005, the B-52 became the second aircraft, after the English Electric Canberra, to mark 50 years of continuous service with its original primary operator. There are six aircraft altogether that have made this list as of 2009; the other four being the Tupolev Tu-95, the C-130 Hercules, the KC-135 Stratotanker, and the Lockheed U-2.
Specifications (B-52H)
B-52H General characteristics- Crew: 5 (pilot, copilot, radar navigator (bombardier), navigator, and Electronic Warfare Officer)
- Length: 159 ft 4 in (48.5 m)
- Wingspan: 185 ft 0 in (56.4 m)
- Height: 40 ft 8 in (12.4 m)
- Wing area: 4,000 sq ft (370 m²)
- Airfoil: NACA 63A219.3 mod root, NACA 65A209.5 tip
- Empty weight: 185,000 lb (83,250 kg)
- Loaded weight: 265,000 lb (120,000 kg)
- Max takeoff weight: 488,000 lb (220,000 kg)
- Powerplant: 8× Pratt & Whitney TF33-P-3/103 turbofans, 17,000 lbf (76 kN) each
- Fuel capacity: 47,975 U.S. gal (39,948 imp gal; 181,610 L)
- Zero-lift drag coefficient: 0.0119 (estimated)
- Drag area: 47.60 sq ft (4.42 m²)
- Aspect ratio: 8.56
B-52H Performance
- Maximum speed: 560 kt (650 mph, 1,000 km/h)
- Combat radius: 4,480 mi (3,890 NM, 7,210 km)
- Ferry range: 10,145 mi (8,764 nm, 16,232 km)
- Service ceiling: 50,000 ft[6] (15,000 m)
- Rate of climb: 6,270 ft/min.[82] (31.85 m/s)
- Wing loading: 120 lb/sq ft (595 kg/m²)
- Thrust/weight: 0.31
- Lift-to-drag ratio: 21.5 (estimated)
B-52H Armament
- Guns: 1× 20 mm M61 Vulcan cannon in a remote controlled tail turret now decommissioned and removed from all operational aircraft
- Bombs: Approximately 70,000 pounds (31,500 kg) mixed ordnance -- bombs, mines, missiles, in various configurations
Avionics
Electro-optical viewing system that uses platinum silicide forward-looking infrared and high resolution low-light-level television sensors.
B-52 Design
Upgrades and modifications
In November 1959, SAC initiated the Big Four modification program (also known as Modification 1000) for all operational B-52s except early B models. The program was completed by 1963. The four modifications were:
- Ability to perform all-weather, low-altitude (below 500 feet or 150 m) interdiction as a response to advancements in Soviet Union's missile defenses. The low-altitude flights were estimated to accelerate structural fatigue by at least a factor of eight, requiring costly repairs to extend service life.
- Ability to launch AGM-28 Hound Dog standoff nuclear missiles
- Ability to launch ADM-20 Quail decoys
- An advanced electronic countermeasures (ECM) suite
The ability to carry up to 20 AGM-69 SRAM nuclear missiles was added to G and H models starting in 1971. Fuel leaks due to deteriorating Marman clamps continued to plague all variants of the B-52. To this end, the aircraft were subjected to Blue Band (1957), Hard Shell (1958), and finally QuickClip (1958) programs. The latter fitted safety straps which prevented catastrophic loss of fuel in case of clamp failure.
Ongoing problems with advanced avionics were addressed in the Jolly Well program, completed in 1964, which improved components of the AN/ASQ-38 bombing navigational computer and the terrain computer. The MADREC (Malfunction Detection and Recording) upgrade fitted to most aircraft by 1965 could detect failures in avionics and weapons computer systems, and was essential in monitoring the Hound Dog missiles. The electronic countermeasures capability of the B-52 was expanded with Rivet Rambler (1971) and Rivet Ace (1973).In order to improve the ability to operate safely at low level during both day and night, the AN/ASQ-151 Electro-Optical Viewing System (EVS), consisting of a Low Light Level Television (LLLTV) and a Forward Looking Infra-Red (FLIR) system mounted in blisters under the noses of B-52Gs and Hs between 1972 and 1976. In order to further improve the B-52s offensive ability, it was decided to fit Air Launched Cruise Missiles (ALCMs). After testing of both the Air-Force backed Boeing AGM-86 and the Navy backed General Dynamics AGM-109 Tomahawk, the AGM-86B was selected for operation by the Boeing B-52 Stratofortress US Military Bomber (and ultimately by the B-1 Lancer). A total of 194 B-52Gs and Hs were modified to carry AGM-86s, carrying 12 missiles on underwing pylons, with 82 B-52Hs further modified to carry another eight missiles on a rotary launcher fitted in the aircraft's bomb-bay. In order to conform with the requirements of the SALT II Treaty for cruise missile capable aircraft to be readily identified by reconnaissance satellites, the cruise missile armed B-52Gs were modified with a distinctive wing root fairing. As all B-52Hs were assumed to be modified, no visual modification of these aircraft was required. In 1990, the stealthy AGM-129 ACM cruise missile entered service. Although originally intended to replace the AGM-86 its high cost and the end of the Cold War stopped production after only 450 had been made. Unlike the AGM-86, no conventional (i.e. non-nuclear) armed version was built.
Structural fatigue, exacerbated by the change to low-altitude missions, was first dealt with in the early 1960s by the three-phase High Stress program which enrolled aircraft at 2,000 flying hours. This was followed by a 2,000-hour service life extension to select airframes in 1966-1968, and the extensive Pacer Plank reskinning completed in 1977. The wet wing introduced on G and H models was even more susceptible to fatigue due to experiencing 60% more stress during flight than the old wing. The wings were modified by 1964 under ECP 1050. This was followed by a fuselage skin and longeron replacement (ECP 1185) in 1966, and B-52 Stability Augmentation and Flight Control program (ECP 1195) in 1967.
Boeing has suggested re-engining the B-52H fleet with the Rolls-Royce RB211 534E-4. This would involve replacing the eight Pratt & Whitney TF33s (total thrust 8 × 17,000 lb) with four RB211s (total thrust 4 × 37,400lb). The RR engines will increase the range and payload of the fleet and reduce fuel consumption. However, the cost of the project would be significant. Procurement would cost approximately US$2.56 billion (US$36 million × 71 aircraft). A Government Accountability Office study of the proposal concluded that Boeing's estimated savings of US$4.7 billion would not be realized and found that it would cost US$1.3 billion over keeping the existing engines. The higher cost was blamed on significant up-front procurement expenditure, necessary re-tooling, and the RB211's higher maintenance cost. The GAO report was subsequently disputed in a Defense Sciences Board report in 2003 and revised in 2004 that identified numerous errors in the prior evaluation of the Boeing proposal, and urged the Air Force to re-engine the aircraft without delay. Further, the DSB report stated the program would save substantial funds, reduce greenhouse gas emissions, and increase aircraft range and endurance, duplicating the results of a Congressionally funded US$3M program office study conducted in 2003. However, the re-engining has not been approved as of 2009. The JT8D has also been suggested as a replacement. It would offer a possible middle-ground solution, as it retains the TF33's sleek aerodynamic shape yet offers higher thrust and improved fuel efficiency.
In 2007 the LITENING targeting pod was fitted and commissioned increasing the combat effectiveness of the aircraft during day, night and under-the-weather conditions in the attack of ground targets with a variety of standoff weapons under the guidance of lasers and the help of high resolution forward-looking infrared sensor (FLIR) for visual display in the infrared portion of the electromagnetic spectrum and charged coupled device (CCD-TV) camera used to obtain target imagery in the visible portion, this technology could also be used in real-time transmission to ground communications networks and government agencies to gather battlefield intelligence, assess battlefield damage, assess terrorist activities and counter drug activity, further advancing the B-52H's capabilities and uses.
Fuel research platform
In September 2006, the The Boeing B-52 Stratofortress US Military Bomber became one of the first US military aircraft to fly using 'alternative' fuel. Syntroleum Corporation, a leader in Fischer-Tropsch process (FT) technology, announced that its Ultra-Clean jet fuel had been successfully tested in a B-52. It took off from Edwards Air Force Base with a 50/50 blend of FT and traditional JP-8 jet fuel which was burned in two of the eight engines on the aircraft. This marked the first time that FT jet fuel was tested in a military flight demo, and is the first of several planned test flights.
On 15 December 2006, tail number 61-0034, Wise Guy took off from Edwards with the synthetic fuel blend powering all eight engines, the first time an Air Force aircraft was completely powered by the mixture. The test flight was captained by Major General Curtis Bedke, commander of the Edwards Flight Test Center, the first time in 36 years that the installation's commander performed a first flight in a flight test program. The flight lasted seven hours, reached an altitude of 48,000 feet, and was considered a success.
On 8 August 2007, Air Force Secretary Michael Wynne certified the B-52H as fully approved to use the FT blend, marking the formal conclusion of the test program.
This program is part of the Department of Defense Assured Fuel Initiative, an effort to develop secure domestic sources for the military energy needs. The Pentagon hopes to reduce its use of crude oil from foreign producers and obtain about half of its aviation fuel from alternative sources by 2016. With the B-52 now approved to use the FT blend, the USAF will use the test protocols developed during the program to certify the C-17 Globemaster III and then the B-1B to use the fuel (the first B-1 test flight took place in March, 2008). The Air Force intends to test and certify every airframe in its inventory to use the fuel by 2011.
