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:

  1. 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.
  2. Ability to launch AGM-28 Hound Dog standoff nuclear missiles
  3. Ability to launch ADM-20 Quail decoys
  4. 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 B-52 (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 were made. Unlike the AGM-86, no conventional (i.e. non-nuclear) armed version was built.

B-52H (61-023), still flying after its vertical stabilizer sheared off in severe turbulence on 10 January 1964.

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 37,400 lb). 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.

Lower deck of the B-52 dubbed the battle station.

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 B-52 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 was 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.

Costs

The costs are in approximate 1955 United States dollars and have not been adjusted for inflation.

B-52 Costs
X/YB-52B-52AB-52BB-52CB-52DB-52EB-52FB-52GB-52H
Unit R&D cost100 million
Airframe26,433,51811,328,3985,359,0174,654,4943,700,7503,772,2475,351,8196,076,157
Engines2,848,1202,547,4721,513,2201,291,4151,256,5161,787,1911,427,6111,640,373
Electronics50,76161,19871,39768,61354,93360,11166,37461,020
Armament47,874482,284293,346548,353931,665862,839840,0001,501,422
Ordnance9,19311,52010,98317,9284,6263,0166,8096,804
Flyaway cost28,380,00014,430,0007,240,0006,580,0005,940,0006,480,0007,690,0009,290,000
Maintenance cost per flying hour9251,0251,0251,182