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.
Beginning with the successful contract bid in June 1946, the B-52 design evolved from a straight wing aircraft powered by six turboprop engines to the final prototype YB-52 with eight turbojet engines and swept wings. The B-52 took its maiden flight in April 1952. Built to carry nuclear weapons for Cold War-era deterrence missions, the B-52 Stratofortress replaced the Convair B-36. A veteran of several wars, the B-52 has dropped only conventional munitions in combat. The B-52's official name Stratofortress is rarely used; informally, the aircraft has become commonly referred to as the BUFF (Big Ugly Fat Fucker).
The B-52 has been in active service with the USAF since 1955. As of December 2015, 58 were in active service with 18 in reserve. The bombers flew under the Strategic Air Command (SAC) until it was disestablished in 1992 and its aircraft absorbed into the Air Combat Command (ACC); in 2010 all B-52 Stratofortresses were transferred from the ACC to the newly created Air Force Global Strike Command (AFGSC). Superior performance at high subsonic speeds and relatively low operating costs have kept the B-52 in service despite the advent of later, more advanced aircraft, including the canceled Mach 3 B-70 Valkyrie, the variable-geometry B-1 Lancer, and the stealth B-2 Spirit. The B-52 completed sixty years of continuous service with its original operator in 2015. After being upgraded between 2013 and 2015, it is expected to serve into the 2040s. The B-52s are expected to reach the end of their service lives by 2045, and be replaced by B-21 Raiders.
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| USAF B-52H Stratofortress engines |
Engines
The eight engines of the B-52 are paired in pods and suspended by four pylons beneath and forward of the wings' leading edge. The careful arrangement of the pylons also allowed them to work as wing fences and delay the onset of stall. The first two prototypes, XB-52 and YB-52, were both powered by experimental Pratt & Whitney YJ57-P-3 turbojet engines of 8,700 lbf (38.70 kN) of static thrust each.
The B-52A models were equipped with Pratt & Whitney J57-P-1W turbojets, providing a dry thrust of 10,000 lbf (44.48 kN) which could be increased for short periods to 11,000 lbf (48.93 kN) with water injection. The water was carried in a 360-gallon tank in the rear fuselage.
B-52B, C, D and E models were equipped with Pratt & Whitney J57-P-29W, J57-P-29WA, or J57-P-19W series engines all rated at 10,500 lbf (46.71 kN). The B-52F and G models were powered by Pratt & Whitney J57-P-43WB turbojets, each rated at 13,750 lbf (61.16 kN) static thrust with water injection.
On May 9, 1961, B-52H started being delivered to the Air Force with cleaner burning and quieter Pratt & Whitney TF33-P-3 turbofans with a maximum thrust of 17,100 lbf (76.06 kN)
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| A view of the lower deck of the B-52, dubbed the battle station |
Flight controls
Because of the B-52's mission parameters, only modest maneuvers would be required with no need for spin recovery. The aircraft has a relatively small, narrow chord rudder, giving it limited yaw control authority. Originally an all-moving vertical stabilizer was to be used, but was abandoned because of doubts about hydraulic actuator reliability. Because the aircraft has eight engines, asymmetrical thrust due to the loss of an engine in flight would be minimal and correctable with the narrow rudder. To assist with crosswind takeoffs and landings the main landing gear can be pivoted 20 degrees to either side from neutral. This yaw adjustable crosswind landing gear would be preset by the crew according to wind observations made on the ground.
The elevator is also very narrow in chord like the rudder, and the B-52 suffers from limited elevator control authority. For long term pitch trim and airspeed changes the aircraft uses an all-moving tail with the elevator used for small adjustments within a stabilizer setting. The stabilizer is adjustable through 13 degrees of movement (nine up, four down) and is crucial to operations during take off and landing due to large pitch changes induced by flap application. B-52s prior to the G models had very small ailerons with a short span that was approximately equal to their chord. These "feeler ailerons" were used to provide feedback forces to the pilot's control yoke and to fine tune the roll axes during delicate maneuvers such as aerial refueling. Due to twisting of the thin main wing, conventional outboard flap type ailerons would lose authority and therefore could not be used. In other words, aileron activation would cause the wing to twist, undermining roll control. Six spoilerons on each wing are responsible for the majority of roll control. The late B-52G models eliminated the ailerons altogether and added an extra spoileron to each wing. Partly because of the lack of ailerons, the B-52G and H models were more susceptible to dutch roll.
| B-52 Stratofortress | |
|---|---|
| Role | Strategic bomber |
| National origin | United States |
| Manufacturer | Boeing |
| First flight | 15 April 1952 |
| Introduction | February 1955 |
| Status | In service |
| Primary users | United States Air Force NASA |
| Produced | 1952–1962 |
| Number built | 744 |
| Unit cost |
B-52B: US$14.43 million (1956); US$126.93M (2016 with inflation)
B-52H: US$9.28M (1962); US$84M (2012 with inflation) |
| Developed into | Conroy Virtus |
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Boeing B-52 Stratofortress
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