The Boeing B-52 Stratofortress is an American long-range, subsonic, jet-powered strategic bomber.
The B-52 was designed and built by Boeing, which has continued to provide support and upgrades.
It has been operated by the United States Air Force (USAF) since the 1950s.
The bomber is capable of carrying up to 70,000 pounds (32,000 kg) of weapons, and has a typical combat range of more than 8,800 miles (14,080 km) without aerial refueling.
Two prototype aircraft with limited operational equipment, used for aerodynamic and handling tests
One XB-52 modified with some operational equipment and re-designated
Only three of the first production version, the B-52A were built, all loaned to Boeing for flight testing.
The first production B-52A differed from prototypes in having a redesigned forward fuselage.
The bubble canopy and tandem seating was replaced by a side-by-side arrangement and a 21 in (53 cm) nose extension accommodated more avionics and a new sixth crew member.
In the rear fuselage, a tail turret with four 0.50 inch (12.7 mm) machine guns with a fire-control system, and a water injection system to augment engine power with a 360 US gallon (1,363 L) water tank were added.
The aircraft also carried a 1,000 US gallon (3,785 L) external fuel tank under each wing.
The tanks damped wing flutter and also kept wingtips close to the ground for ease of maintenance.
The last B-52A was modified and redesignated NB-52A in 1959 to carry the North American X-15.
A pylon was fitted under the right wing between the fuselage and the inboard engines with a 6 feet x 8 feet (1.8 m x 2.4 m) section removed from the right wing flap to fit the X-15 tail.
Liquid oxygen and hydrogen peroxide tanks were installed in the bomb bays to fuel the X-15 before launch.
Its first flight with the X-15 was on 19 March 1959, with the first launch on 8 June 1959.
The NB-52A, named “The High and Mighty One” carried the X-15 on 93 of the program’s 199 flights.
The B-52B was the first version to enter service with the USAF on 29 June 1955 with the 93rd Bombardment Wing at Castle AFB, California.
This version included minor changes to engines and avionics, enabling an extra 12,000 pounds of thrust using water injection.
Temporary grounding of the aircraft after a crash in February 1956 and again the following July caused training delays, and at mid-year there were still no combat-ready B-52 crews.
Of the 50 B-52Bs built, 27 were capable of carrying a reconnaissance pod as RB-52Bs.
The 300 pound (136 kg) pod contained radio receivers, a combination of K-36, K-38, and T-11 cameras, and two operators on downward-firing ejection seats.
The pod required only four hours to install.
The NB-52B was B-52B number 52-0008 converted to an X-15 launch platform.
It subsequently flew as “Balls 8” in support of NASA research until 17 December 2004, making it the oldest flying B-52B.
It was replaced by a modified B-52H.
The B-52C’s fuel capacity was increased to 41,700 US gallons by adding larger 3000 US gallon under wing fuel tanks.
The gross weight was increased by 30,000 pounds (13,605 kg) to 450,000 pounds.
A new fire control system, the MD-9, was introduced on this model.
The belly of the aircraft was painted with anti-flash white paint, which was intended to reflect the thermal radiation of a nuclear detonation.
The RB-52C was the designation initially given to B-52Cs fitted for reconnaissance duties in a similar manner to RB-52Bs.
As all 35 B-52Cs could be fitted with the reconnaissance pod, the RB-52C designation was little used and was quickly abandoned.
The B-52D was a dedicated long-range bomber without a reconnaissance option.
The Big Belly modifications allowed the B-52D to carry heavy loads of conventional bombs for carpet bombing over Vietnam, while the Rivet Rambler modification added the Phase V ECM systems, which was better than the systems used on most later B-52s.
Because of these upgrades and its long range capabilities, the D model was used more extensively in Vietnam than any other model.
Aircraft assigned to Vietnam were painted in a camouflage color scheme with black bellies to defeat searchlights.
The B-52E received an updated avionics and bombing navigational system, which was eventually debugged and included on following models.
One -E aircraft was modified as a test-bed for various B-52 systems.
Redesignated NB-52E, the aircraft was fitted with canards and a Load Alleviation and Mode Stabilization system which reduced airframe fatigue from wind gusts during low level flight.
In one test, the aircraft flew 10 knots (11.5 mph, 18.5 km/h) faster than the never exceed speed without damage because the canards eliminated 30% of vertical and 50% of horizontal vibrations caused by wind gusts.
One aircraft leased by General Electric to test TF39 and CF6 engines.
This aircraft was given J57-P-43W engines with a larger capacity water injection system to provide greater thrust than previous models.
This model had problems with fuel leaks which were eventually solved by several service modifications: Blue Band, Hard Shell, and QuickClip.
The B-52G was proposed to extend the B-52’s service life during delays in the B-58 Hustler program.
At first, a radical redesign was envisioned with a completely new wing and Pratt & Whitney J75 engines.
This was rejected to avoid slowdowns in production, although a large number of changes were implemented.
The most significant of these was a new “wet” wing with integral fuel tanks, increasing gross aircraft weight by 38,000 pounds (17,235 kg).
In addition, a pair of 700 US gallon (2,650 L) external fuel tanks were fitted under the wings on wet hard points.
The traditional ailerons were also eliminated, and the spoilers now provided all roll control.
The tail fin was shortened by 8 feet (2.4 m), water injection system capacity was increased to 1,200 US gallons (4,540 L), and the nose radome was enlarged.
The tail gunner was relocated to the forward fuselage, aiming via a radar scope, and was now provided with an ejection seat.
Dubbed the “Battle Station” concept, the offensive crew faced forward, while the defensive crew on the upper deck faced aft.
The B-52G entered service on 13 February 1959
The last B-52G was dismantled under The New START treaty requirements in December 2013.
The B-52H had the same crew and structural changes as the B-52G.
The most significant upgrade was the switch to TF33-P-3 turbofan engines which, despite the initial reliability problems (corrected by 1964 under the Hot Fan program), offered considerably better performance and fuel economy than the J57 turbojets.
The ECM and avionics were updated, a new fire control system was fitted, and the rear defensive armament was changed from machine guns to a 20 mm M61 Vulcan cannon.
The final 18 aircraft were manufactured with provision for the ADR-8 countermeasures rocket, which was later retrofitted to the remainder of the B-52G and B-52H fleet.
A provision was made for four GAM-87 Skybolt ballistic missiles.
The aircraft’s first flight occurred on 10 July 1960, and it entered service on 9 May 1961.