The last production version of the Stratofortress was the B-52H (Model 464-261), a total of 102 being built. As with the B-52G, manufacture of the B-52H was undertaken solely at Wichita. Today, the B-52H is the only version of the Stratofortress still in service, with all previous versions having either been consigned to storage or scrapped. It is likely that the B-52H will still be in service well into the 21st century.
There were two separate B-52H contracts. Letter Contract AF33(600)-38778 was signed on May 6, 1960 and covered 62 aircraft with FY 1960 funds. Serials were 60-001/0062. The second (and last) contract was AF33(600)-41961 which was signed on June 28, 1960, but not finalized until late 1962. Serial numbers were 61-0001/0040. Z
The most noticeable difference between the B-52H and earlier versions was the replacement of the water-injected J57 turbojet engines by Pratt & Whitney TF33-P-3 turbofans. The TF33 was a military adaptation of the JT3D turbofan, which had originally been produced as an adaptation of the J57 to the commercial market. The TF33 engines of the B-52H offered 30 percent more thrust than the J57s of the G-model, even when the J57s were using water injection. A maximum thrust of 17,100 pounds could be delivered, producing much better airfield performance and an extra margin of safety during heavyweight takeoffs. For the B-52H, the ground roll was about 500 feet less than that of the B-52G.
In addition, the TF33 was much cleaner and quieter when operating at full power. It was much more environmentally-friendly than the water-injected J57, and did not leave behind it the same trail of noxious black smoke. The TF33 engine is much quieter, which results in a less-noisy cabin and a corresponding reduction in crew fatigue. The deletion of the water injection made it unnecessary to maintain large stocks of (prepositioned) distilled water, which had hindered the rapid deployment of the B-52G and earlier versions.
The TF33 was also much more economical, offering a notable improvement in range. Combat radius of the B-52H was 4176 nautical miles with a 10,000 pound bombload, as compared with only 3550 nautical miles for the B-52G.
The use of the new engines markedly altered the appearance of the nacelles. The TF33 engine had a larger forward compression stage than the J57, which required a larger-diameter intake and a by-bass air outlet. Consequently, it was quite easy to tell the difference between a B-52G and a B-52H.
The TF33 had a much quicker throttle response than the J57. This caused an unexpected problem, since too-rapid a movement of the throttle could cause the aircraft to pitch up at a rate beyond the pilot's ability to correct with the available elevator authority. This effect was aggravated by fuel slosh--the fuel in the wet wing rushing to the rear of the wing during acceleration and moving the center of gravity aft. In order to prevent this from happening, mechanical thrust gates had to be added to the throttle quadrant. These thrust gates can be positioned for any maximum thrust desired--once set the pilot cannot inadvertently jam the throttles forward and get more thrust than desired. Air refuelling capability was improved by altering the spoiler positions so that the outward segments could extend up about ten degrees, making small lateral corrections possible without inducing pitch-up.
The defensive tail armament was changed. The quartet of 0.50-inch machine guns carried by earlier versions was replaced by a single General Electric M61 20-mm six-barreled rotary cannon. The maximum firing rate was 4000 rounds per minute. The magazine carried 1242 rounds of ammunition. The Emerson AN/ASG-21 fire control system was installed as standard. The gunner was still seated in the main crew compartment forward of the wing leading edge, sitting in an upward-firing rearward-facing ejector seat beside the electronic warfare officer.
The B-52H has the same short vertical fin that was developed for the B-52G. The height of the fin is 22 feet 11 inches.
The B-52H was provided with equipment intended to make low-altitude operations safer and easier on the crews. The H was the first version to receive this new equipment, although some Ds, Es, Fs, and Gs were later retrofitted. The new systems provided relief from the tremendous strain posed on pilots and navigators in flying at low altitudes at high speeds for long periods of time. Instrumentation was provided for terrain following. An advanced capability radar (ACR) radar was fitted which could give three- dimensional information on a dual-mode video display on the pilot's and navigator's instrument panel. The height of the terrain was shown continuously at selected distances of three, six or ten miles ahead of the aircraft. The pilot could select either a PLAN mode which gave a map-like display or a PROFILE mode which showed the terrain height at various ranges ahead of the aircraft. In order to assist the pilot in flying at low level, control wheel steering was built into the MA-2 autopilot. This reduced the amount of control forces and the frequency of control movements required to fly the aircraft.
The crew of the B-52H was originally six. The pilot and copilot sat side-by-side on the upper flight deck, with the pilot on the left. Behind them on the upper flight deck were the electronic warfare officer and the gunner, seated side-by-side and facing to the rear. All four of these crew members sat in upward-firing Weber ejector seats equipped with the M-3 catapult. These seats do not have zero-zero capability, but are good at 165 km/hr and zero altitude. The radar navigator who was responsible for weapons delivery and for guiding the aircraft past terrain while flying at low altitude, plus the navigator who was responsible for getting the aircraft from point A to point B, both sat side-by side on the lower fuselage deck, facing forward. Both of these crewmen sat on downward-firing Castle-built ejector seats equipped with the M-4 catapult. These downward-firing seats are cleared for operation at speeds as low as 220 km/hr at a minimum altitude of 250 feet.
There was no B-52H prototype as such, but the TF33 turbofan engines were first tested on a B-52G (serial number 57-6471), the aircraft being temporarily redesignated YB-52H. Following the tests, the aircraft reverted to standard B-52G configuration. The first true B-52H flew on July 20, 1960.
Delivery of the B-52H to operational units began on May 9, 1961 when the 379th Bombardment Wing at Wurtsmith AFB in Michigan received its first aircraft. The last B-52H was delivered to the 4136th Strategic Wing at Minot AFB on October 26, 1962, bringing production of the Stratofortress to an end.
The new TF33 turbofans did experience some initial teething troubles. There were difficulties with throttle creep, hard or slow starting, flameouts, and uneven throttle alignment. The engine consumed too much oil, turbine blades frequently failed, and inlet cases often cracked. A program known as Hot Fan was instituted in mid-1962 to correct these problems and to increase the reliability of the TF33. The Hot Fan project was interrupted by the Cuban Missile Crisis of October 1962, when all Stratofortresses had to stand alert, and was not resumed until January 1963. The project was completed by the end of 1964.
Shortly before the Cuban missile crisis, cracks were discovered in the wings of two B-52Hs, at the place where fuselage and wing joined. The taper lock fasteners were found to be the culprits, since they were particularly susceptible to corrosion. A project known as Straight Pin was set up to fix this problem. Wing terminal fasteners were replaced by those having extremely low interference and cracked fitting holes were cleaned up by oversized reaming. Although interrupted by the missile crisis, the project was virtually complete by the end of 1962.
Starting in January 1963, a pair of cartridge starters were installed in every B-52, in an attempt to make it possible to start the engines faster and get the Stratofortress off the ground quicker in the event of a crisis. In addition, the provision of cartridges would, it was hoped, allow dispersed or post-strike B-52s to get off the ground from airfields that lacked electrical power carts and other ground support equipment. The installation of this equipment reduced the reaction time by about two minutes. The Air Force was still not satisfied with the speed with which its B-52 force could get off the ground, and in 1974 a project known as Quick Start was instituted in which every single engine on the B-52G and H models was provided with a cartridge starter. This permitted instantaneous ignition of all eight engines and greatly reduced the amount of time required before the aircraft could get rolling.
The bomb bay of the B-52H occupies almost the entire center section of the fuselage and is 28 feet long and 6 feet wide. It is enclosed by double-pane doors. Three interconnected and hydraulically-activated sections on each side can be opened in flight to release the weapons. The B-52H can carry two four-bomb or up to three nine-bomb clips internally. Conventional internal B-52 loads include 27 each of SUU-30H/B (CBU-52, -58, and -71), Mk 82 500-lb conventional orr Snakeye bombs, MK 36 500-lb destructor bombs, Mk 59 or 62 500-lb Quickstrike mines, or M117 750-pound bombs (conical fin, destructor, retarded, or air inflatable retard); 18 each of MJU-1B countermeasures sets or M129 leaflet dispensers; 12 each of Mk 52 2000-pound mines; six each of CBU-87 combined effects munitions or CBU-89 Gator. Alternatively a clip of 8 Mk 84 2000-lb bombs, Mk 41 2000-lb destructors, Mk 55 2000-lb bottom mines, Mk 56 2000-lb moored magnetic mines, Mk 60 2360-lb captive torpedoes (CapTor), Mk 64 or 65 2000-lb Quickstrike mines, or AGM-86C cruise missiles can be carried inside the bomb bay. A pair of 9-megaton B53 thermonuclear weapons can also be carried inside the bomb bay.
The B-52H had originally been expected to carry four Douglas GAM-87 Skybolt air-to-surface missiles as the main offensive weapon. These were to be carried two each on an inverted Y pylon underneath each wing. The Skybolt was an air-launched ballistic missile that would have carried a W59 nuclear warhead inside a Mk 7 re-entry vehicle. Development was initiated in the latter half of the 1950s. Decision to proceed with the Skybolt was reached in February of 1960, with initial deployment scheduled to begin in 1964. In June of 1960, the British government ordered 100 Skybolts to be carried by the Avro Vulcan. In December of 1962, President Kennedy cancelled the Skybolt missile for political and economical reasons. The cancellation of the Skybolt project forced the B-52H to rely on a combination of gravity thermonuclear bombs and underwing-mounted AGM-28 Hound Dog missiles, the same combination as carried by the B-52G.
Two types of external pylons can be fitted underneath the wings of the B-52H. The longer variety was originally used for carrying the AGM-28 Hound Dog cruise missile, whereas the shorter one was designed for conventional weapons carriage, and is known as the "stub" wing pylon.
The shorter variety of underwing pylon is only compatible with aircraft that were not modified to carry ALCMs. The short pylon was originally fitted with the I-beam rack adapter, which could carry up to 12 weapons on each pylon. Two MER-1-6 or -6As are attached. Among the weapons that can be carried were 24 each of the SUU-38H/B dispenser (CBU-52, -58, and -71 units), CBU-89, Mk 82 500-lb bombs (conventional or Snakeye retarded), Mk 36 500-lb Destructor bombs, Mk 59 or Mk 62 500-lb Quickstrike mines, M117 750-lb bombs (conical fin, retarded, and Air inflatable retard), MC-1 chemical dispenser, CBU-72, Mk 20 Rockeye II cluster bomb units, or M129 leaflet dispensers. Because of store weight, only 22 CBU-87 Combined Effects Munitions units can be carried, with the aft center station on the forward left MER and the forward center section of the aft right MER being empty. Normally, only one type of bomb is carried per mission. When 8 weapons are carried, they are mounted on the forward and aft shoulder stations only. When 10 weapons are carried, they are mounted on the forward and aft shoulder stations and on the center middle station. When 12 weapons are carried, they are mounted on the shoulder stations only.
Like the B-52G, the B-52H was later provided with the AGM-69 Short-Range Attack Missile (SRAM) and the Boeing AGM-86 Air Launched Cruise Missile (ALCM). Like the B-52G, the B-52H could carry 12 AGM-86B missiles underwing, six on each of the ALCM long-variety underwing pylons. The unratified SALT II agreement stipulated that no more that 130 ALCM bombers could be deployed by the USAF. The delivery of the 131st ALCM-capable aircraft (B-52H serial number 60-0055, appropriately named Salt Shaker) on November 28, 1986 was a technical violation of this treaty. Eventually, a total of 194 Stratofortresses were converted into ALCM launchers. Since the B-52H was readily identifiable by its turbofan engines, no special modifications were needed to make it comply with the provisions of SALT II.
Another weapon that can be carried by the B-52H is the General Dynamics/McDonnell Douglas AGM-129A Advanced Cruise Missile (ACM), which was developed during the Reagan administration as a stealthy replacement for the AGM-86B air launched cruise missile. The AGM-129B is a version that incorporated structural and software changes, along with a different nuclear warhead for a classified cruise missile mission. Deliveries began in June of 1990. It is powered by a Williams F112-WR-110 turbofan engine, which gives the missile a range of more than 1800 nautical miles. The weight is 2750 lb, and it carries a 200-kiloton yield W80-1 nuclear warhead. There is no ACM variant with a conventional mission, or at least none that has been revealed (although the B version is rumored to have a conventional capability). At one time, it was planned to produce 1461 of these weapons, but due to cost overruns and budget cuts, the program was cancelled in 1992 by the Bush administration after only 640 had been built.
Up to 12 of these AGM-129A ACM missiles can be carried externally on the underwing ALCM pylons of the B-52H. The missile is, however, too large to fit inside the bomb bay of the B-52H. Details about the deployment of the AGM-129A among the B-52H fleet seem to be classified. It is known that the B-52Hs of the 410th BW at K I Sawyer AFB were modified to receive the ACM in the late 1980s, but it is not certain that these missiles were ever actually fitted. The 7th BW at Carswell was also earmarked to receive the ACM, but this unit was deactivated in 1992. The 410th was scheduled to be deactivated in 1994. This missile reported is also carried by the Rockwell B-1B Lancer and the Northrop B-2 Spirit. The AGM-129 cruise missile was taken out of service on April 24, 2012
Later modifications made it possible for the B-52H to be able to carry eight more AGM-86B missiles internally in a Common Strategic Rotary Launcher (CSRL), which was not fitted to the B-52G. CSRL-equipped B-52Hs can therefore carry up to 20 AGM-86B cruise missiles (8 on the CSRL, plus six each on the underwing pylons. The CSRL program began in 1988 and the first CSRL-equipped B-52Hs appeared later that year. The rotary launcher is fitted inside the bomb bay and is attached to yokes. New electrical and hydraulic lines were fitted inside the bomb bay to operate and control the launcher. The launcher and its associated systems weigh approximately 5000 pounds. Instead of a battery of AGM-86Bs, the CSRL can carry as many as four B28 70-350 kT nuclear bombs or as many as eight B61 (10-500 kiloton yield) or B83 (1-2 megaton yield) nuclear bombs. However, the CSRL cannot carry the AGM-129A ACM, which is too big to fit inside the bomb bay. Some 82 of the B-52Hs were provided with CSRL capability. The CSRL is not compatible with either the B-1 or the B-2 bombers.
In a program known as Jolly Well, major components of the AN/ASQ-38 bomb/navigation system originally fitted to the B-52E to H models were modified. This involved some engineering changes to improve low-level terrain avoidance capabilities. By the time that the Jolly Well program was completed in 1964, some 480 B-52 aircraft had been modified.
One of the more unusual missions of the B-52H was its involvement with the Lockheed D-21 ramjet-powered reconnaissance drone. The D-21 was powered by a Marquardt RJ-43-MA-11 ramjet and cruised at Mach 3.3 at an altitude of 90,000 feet. The range was 1250 nautical miles. The D-21 was guided by an inertial navigation system which flew a pre-programmed flight profile. Having completed its camera run, the drone was directed to fly to a recovery point, where the entire palletized camera unit was ejected and allowed to descend by parachute. The drone was then blown apart by an explosive charge. It was planned that the camera unit with the exposed film would be snared in midair by a C-130 Hercules equipped with a mid-air recovery system. The D-21 was originally to be launched at high speed and high altitude from the back of a specially-modified Lockheed A-12 Mach-3 reconnaissance aircraft, which was known as an M-12. Unfortunately, on July 31, 1966, a launch malfunction resulted in the loss of the M-12 and the death of one of the crewmen. Clarence "Kelly" Johnson was so upset by the death of one of his team that he cancelled the entire M-12/D-21 program. Instead, the D-21s were modified to incorporate a less-sensitive inlet and were adapted to be launched from the underwing pylon of a B-52H. Launched from a slower, lower-flying platform, the D-21 had to be accelerated to its operational Mach speed and altitude by means of a rocket booster attached to the underside of the drone, which separated from the vehicle once cruising speed was reached. This new operation was given the code name *Senior Bowl*.
The 4200th Support Squadron of the 4200th Test Wing operated two Senior Bowl B-52Hs (60-0021 and 60-0036) that were modified to carry a D-21B reconnaissance drone underneath each wing between the inboard engines and the fuselage. The first D-21B test launch from a B-52H was made on November 6, 1967. The first operational launch was made on September 9, 1969. The fourth and final operational launch was made on March 20, 1971. The operational missions were overflights of China. In order to maintain tight security, the B-52s would leave Beale AFB at night and land at Guam. Just before dawn the next day, the bomber would leave Guam and head for its launch point. After launch, the B-52 would return to Guam while the drone headed toward China. These missions were not all that successful, and there were problems with the final film recovery stage at the end of the mission. On one of these missions, the drone developed a malfunction and crashed in a mountainous area of China, the incident resulting in a protest by Peking to Washington that SR-71s were violating their airspace. Because of operational difficulties, political considerations, and the high cost of these limited-duration flights, the Senior Bowl program was terminated on July 23, 1971.
Between 1972 and 1976, all surviving B-52Hs were provided with the AN/ASQ-151 advanced Electro-optical Viewing System (EVS) to give the B-52 crew enhanced vision when flying at low level at night. The system is contained in two prominent fairings underneath the nose. The port fairing contains a steerable Westinghouse AN/AVQ-22 low-light-level television camera, whereas the starboard unit contains a Hughes AN/AAQ-6 forward-looking infrared (FLIR) sensor. Both units feed information into video display screens for the pilot, copilot, and both navigators. Data that can be presented on these screens includes overlaid terrain avoidance profile trace in both TV or FLIR mode, alphanumeric symbology which includes a height reading from the radar altimeter and time-to-go before weapons release, as well as indicated airspeed, heading error and bank steering, artificial horizon overlay and attitude and position of the sensor in use.
The Phase VI ECM Defensive Avionics Systems (ECP2519) was an upgrade program designed to improve the electronic countermeasures capabilities of the B-52H fleet. Known under the code name Rivet Ace, the program was started in December of 1971, but it took several years of development and testing before the final configuration was decided, and then several more years after that before the entire fleet could be upgraded. Upgrades were still continuing as recently as the late 1980s. Externally, the most visible change was in the extreme aft fuselage, which was extended further rearward by 40 inches to accommodate the extra equipment. However, the addition of so many antennae required that many other assorted bumps and warts be added over the exterior, which spoiled the fairly clean lines of the original B-52H. The equipment added as part of Phase VI consisted of an AN/ALR-20A panoramic countermeasures receiver which detects an displays all radio frequency signals within the operating range of the system and is fed by antennae located all over the aircraft , an AN/ALQ-117 active countermeasures set with antennae facing sideways from the nose, an AN/ALR-46(V) digital radar warning receiver set which receives, analyzes, and displays terminal threat data, an AN/ALQ-122 false target generator system (sometimes known as Smart Noise Operation Equipment or deception jammer) which links a computer to two AN/ALT-16A transmitters, AN/ALT-28 noise jammers in a bulge on top of the nose just ahead of the windshield, AN/ALQ-153 tail warning radar set, AN/ALT-32H high-frequency radar and communications jammers, and AN/ALT-32L high and low-band radar and communication jamming sets, ALQ-155 Power Management System which is capable of simultaneously countering a wide variety of threats using various power outputs, two AN/ALT-16A barrage-jamming sets, 12 AN/ALE-20 flare dispensers (192 flares) located six each on the lower surfaces of the horizontal stabilizers, and eight AN/ALE-24 chaff dispensers (four dispensers on the underside of each wing forward and between the flaps, with each dispenser carrying 1125 bundles). Subsequent refinements entailed replacement of the AN/ALQ-117 unit in mid-1988 by an AN/ALQ-172(V)2 active countermeasures unit, with updated countermeasures and an electronically steerable phased-array antennae farm.
The B-52G and H initially carried AN/ALE-25 forward-firing chaff rocket pods mounted on pylons installed on the forward wing leading edges between the engines. Although the system was eventually deleted, the mounting pylons were retained for the carrying of various range instrumentation pods. These pylons have given some people the impression that the B-52 is capable of carrying AIM-9 Sidewinder missiles.
Subsequent refinements entailed replacement of the AN/ALQ-117 unit in mid-1988 by an AN/ALQ-172(V)2 active countermeasures unit, with updated countermeasures and an electronically steerable phased-array antennae farm.
By the mid-1970s, the AN/ASQ-38 bombing/navigation equipment initially fitted to the B-52G and H was showing signs of advanced age and was increasingly prone to malfunctions and the Air Force started shopping around for alternatives. The result was the AN/ASQ-176 Offensive Avionics System (OAS), which was first installed in the first half of the 1980s. The system made extensive use of digital technology, and incorporated a Mil-Std-1553A digital databus as well as a new radar altimeter, an attitude heading reference system, an inertial navigation system, plus missile interface units and major modification to the primary attack radar. There are five functional subsystems: interface, controls and display, computational, navigational, and weapons delivery. It makes use of the AN/AYK-17 digital data set, the AN/ASQ-175 control-display set, the AN/AYQ-10 ballistics computer set, the AN/ASN-136 inertial navigation set, the AN/APN-224 radar altimeter, The AN/ASN-134 attitude heading reference system, the AN/APN-218 Doppler radar, the OY-73/ASQ-176 radar set group, the AN/AWQ-3 control monitor set, the RO-521/ASQ-176 video recorder, and FCP tape recorder. The mission tapes fed the flight plan into the system at the beginning of the mission. The new system was considerably more reliable than the AN/ASQ-38 which it replaced, and was specially configured for low-level use and was hardened against electromagnetic pulse effects. The last modifications were completed by the end of 1986.
In 1985, work began on the replacement in all B-52Hs and some B-52Gs of the ASQ-176 unit by the Norden AN/APQ-156 Strategic Radar which incorporated synthetic aperture technology. This involved the fitting of new controls and dispays as well as a new antenna electronics unit and an improved radar processor.
In October of 1991, the gunner's station was removed as an economy measure, reducing the crew complement to only five. The gunner's ejector seat was, however, retained, and can now be occupied by an instructor or flight examiner who often goes along on training missions. The M61A1 Vulcan 20-mm cannon in the tail was taken out during 1991-94 and the gun opening was covered over by a perforated plate, although the wiring and instruments associated with the gun were all retained so that the gun could in principle be reinstalled, although there are no longer any trained gunners available to operate it.
In 1994, the latest B-52H modification program began, the Conventional Enhancement Modification (CEM) program. CEM was designed to give the B-52H a capability for conventional warfare that it had not previously possessed. During the early 1990s, the USAF had planned that the B-52G would perform the conventional and maritime mission, with the B-52H being restricted to the nuclear standoff role. However, the B-52Gs were retired and the B-52H had to be able to take over some of its conventional warfare duties. The first stage in the process was the addition of AGM-142A and Harpoon capability to the B-52H. This was made possible by adding the Heavy Stores Adapter Beam (HSAB) to the underwing weapons pylon, which made it possible to carry weapons that were too long or too heavy to be accommodated on the I-beam rack adapter. The HSAB, which was originally fitted to the B-52G, made it possible to carry up to nine large weapons on each pylon externally, the precise number depending on which weapon is being carried. Later, a Global Positioning System (GPS) navigation system was added, with receivers located at the offensive station. An AN/ARC-210 VHF/UHF radio with secure voice encryption capability was added, and Have Quick II anti-jam features were added to the UHF wavelengths available at the pilots' and offensive stations. SINCGARS anti-jam/secure capability was added for VHF communications. The Military Standard 1760 databus was added to prepare the B-52H for a new generation of weapons not yet in the inventory such as the Joint Direct Attack Munition (JDAM), the Joint Stand-Off Weapon (JSOW), and the Wind-Corrected Munitions Dispenser (WCMD).
Among the weapons that the HSAB modification now enables the B-52H to carry are the Rafael/Lockheed Martin AGM-142A Raptor inertial/TV guided missile, the AGM-84 Harpoon antiship missile, the AGM-84E SLAM, the GBU-10, the MK84 or Mk 60 CapTor mine, the GBU-12, Mk 55/56 mines or JDAM, Mk 40 DST mines, British 1000-lb or 2000-lb bombs, or any bomb that can be carried by the I-beam.
The version of the Harpoon that is carried currently by the B-52Hs is the AGM-84D Block 1C, but a Block 1D version with enhanced range is planned for the future. The B-52H carries the Harpoon only externally, and can carry up to 12 of these missiles on the underwing pylons. Currently, the 96th BS has all the Harpoon-modified aircraft. The first live Harpoon launch by a B-52H took place on July 25, 1996. Although the B-52H can self-target its own Harpoons, the usual practice is to use a Navy aircraft such as an S-3 Viking or a P-3 Orion as an external targeting platform. By 1997, the specialized HACLCS equipment that needs to be fitted to Harpoon-capable B-52Hs is scheduled to be replaced by a new Harpoon Stores Management Overlay (SMO) system, which will allow the B-52H's offensive team (radar navigator and navigator) to load Harpoon-specific weapons software in order to target and launch the weapons.
All the B-52Hs in the active inventory are capable of carrying ALCMs. All have Cruise Missile Integration (CMI) and Advanced Cruise Missile Integration (ACMI), which enables them to carry either 12 AGM-86B/C ALCMs or 12 AGM-129A ACMs on external pylons. All B-52Hs can carry ACMs externally, but the ACM is too large to be carried on the internal rotary launcher. The AGM-86C (version of AGM-86 with conventional warheads) was retired in November 2019
Proposals to re-engine the B-52H fleet have been under consideration since 1975. Newer, more modern engines would reduce fuel costs, extend the range, and reduce the amount of required maintenance. However, none of these proposals ever got past the paper stage. In 1996, Boeing issued an unsolicited proposal to the USAF to re-engine the B-52H fleet with Rolls-Royce RB.211-535E4-B turbofans, rated at 43,100 lb.s.t. each. The RB.211 turbofan currently powers some versions of the Boeing 747, 757, and 767 commercial transports. According to the proposal, four Rolls-Royce turbofans would replace the set of eight TF33 turbofans currently fitted to the B-52H, with one RB.211 being mounted on each underwing pylon.
The B-52H has been confirmed to have been disarmed of the capability to carry free-fall nuclear bombs. The only nuclear weapon these aircraft are presently certified to carry is the AGM-86B Air Launched Cruise Missile, which is set to eventually get replaced by a new stealthy missile under development now under the Long Range Stand Off program, or LRSO.
Since the mid-1990s, the B-52H has been the only variant remaining in military service; it is currently stationed at: Minot Air Force Base, ND – 5th Bomb Wing Barksdale Air Force Base, LA – 2nd Bomb Wing (active Air Force) and 307th Bomb Wing (Air Force Reserve Command) One B-52H is assigned to Edwards Air Force Base and is used by Air Force Materiel Command at the Air Force Flight Test Center. One additional B-52H is used by NASA at Dryden Flight Research Center, California as part of the Heavy-lift Airborne Launch program. From 2 to 3 September 1996, two B-52Hs conducted a mission as part of Operation Desert Strike. The B-52s struck Baghdad power stations and communications facilities with 13 AGM-86C conventional air-launched cruise missiles (CALCM) during a 34-hour, 16,000-mile round trip mission from Andersen AFB, Guam – the longest distance ever flown for a combat mission. On 24 March 1999, when Operation Allied Force began, B-52 bombers bombarded Serb targets throughout the Federal Republic of Yugoslavia, including during the Battle of Kosare. The B-52 contributed to Operation Enduring Freedom in 2001 (Afghanistan/Southwest Asia), providing the ability to loiter high above the battlefield and provide Close Air Supportd munitions, a mission which previously would have been restricted to fighter and ground attack aircraft. In late 2001, ten B-52s dropped a third of the bomb tonnage in Afghanistan. B-52s also played a role in Operation Iraqi Freedom, which commenced on 20 March 2003 (Iraq/Southwest Asia). On the night of 21 March 2003, B-52Hs launched at least 100 AGM-86C CALCMs at targets within Iraq.
60-0001/0013 Boeing B-52H-135-BW Stratofortress c/n 464366/464378 60-0014/0021 Boeing B-52H-140-BW Stratofortress c/n 464379/464386 60-0022/0033 Boeing B-52H-145-BW Stratofortress c/n 464387/464398 60-0034/0045 Boeing B-52H-150-BW Stratofortress c/n 464399/464410 60-0046/0057 Boeing B-52H-155-BW Stratofortress c/n 464411/464422 60-0058/0062 Boeing B-52H-160-BW Stratofortress c/n 464423/464427 60-0063/0070 cancelled contract for Boeing B-52G 61-0001/0013 Boeing B-52H-165-BW Stratofortress c/n 464428/464440 61-0014/0026 Boeing B-52H-170-BW Stratofortress c/n 464441/464453 61-0027/0040 Boeing B-52H-175-BW Stratofortress c/n 464454/464467
Engines: Eight Pratt & Whitney TF33-P-3 turbofans, each rated at 17,000 lb.s.t.
Performance: Maximum speed 632 mph at 23,800 feet, 603 mph at 35,000
feet, 560 mph at 46,650 feet. Cruising speed 525 mph. Stalling speed
169 mph. Initial climb rate 6270 feet per minute. Service ceiling at
combat weight 47,700 feet. Combat radius 4825 miles with 10,000 pound
bombload. Ferry range 10,145 miles. Takeoff ground run 7240 feet.
Takeoff over 50-foot obstacle 9580 feet.
Dimensions: Length 156 feet 0 inches, wingspan 185 feet 0 inches,
height 40 feet 8 inches, wing area 4000 square feet.
Weights: 172,740 pounds empty, 306,358 pounds combat, 488,000 pounds
Fuel: Internal fuel 299,434 pounds, plus provision for 9114 pounds in
two 700-US gallon non-jettisonable underwing tanks.
Armament: One 20-mm M61 cannon with 1242 rounds in tail turret. This
weapon, along with the associated gunner, has now been removed from
most B-52Hs. Maximum offensive payload 50,000 pounds.
Nuclear: In the nuclear mision mode, can carry the Common Strategic
Rotary Launcher (CERM) in the aft bomb bay which can accommodate up to
eight B83 or B61 nuclear weapons or eight AGM-86B or AGM-129A cruise
missiles. All B-52Hs have received Cruise Missile Integration and/or
Advanced Cruise Missile Integration) upgrades which enable them to
carry 12 additional AGM-86Bs or AGM-129As, six on each underwing
Conventional: For land attack, can carry up to 27 500-lb Mk 82 or
750-lb M117 bombs internally. Alternatively, 27 cluster bombs
(CBU-52, CBU-58, CBU-71, CBU-87, or CBU-89), 18 each of British
1000-pound bombs and M129 leaflet bombs, eight each of 2000 pound
Mk 84 (LDGP, AIR, and Mk 41 DST mine), AGM-86C cruise missiles, Mk 55/56
mines, Mk 60 CapTor mine, and o Mk 63/65 QS mines, or six each
of TMD (CBU-87 and CBU-89) can be carried.
There are two external conventional
configurations, the Conventional External Munitions (CEM) modified
aircraft with a Heavy Stores Adaptation BEAM underneath each wing and
non-CEM modified aircraft which have the old AGM-128 Hound Dog pylons
in the same position with a rack adaptor and two Multiple Ejector
Racks. Stores carried by these two external configurations are as
Store CEM-modified B-52H non-CEM-modified B-52H Mk82 18 24 M117 18 24 CBU-52/58/71/89 18 24 CBU-87 22 18 GBU-15 10 0
For stand-off missions, the B-52H can carry either 12 AGM-86C ALCMs, eight AGM-130A rocket-powered bombs, or three AGM-141 Raptor missiles with data link pods. For naval operations, the B-52H can carry either eight Mk 55/15 or Mk 60 mines internally or ten Mk 60 mines on wing pylons. Alternatively, eight AGM-84 Harpoon antiship missiles can be carried on the wing pylons.