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All About B-52 Stratofortress

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The Boeing B-52 Stratofortress is a long-range jet strategic bomber flown by the United States Air Force (USAF) since 1954. It replaced the Convair B-36 and the Boeing B-47. Although built for the role of Cold War-era nuclear deterrent, its conventional capabilities now take priority. The aircraft has the longest range of any bomber and carries a heavy strategic or tactical weapons load. Its economy in operation and high subsonic performance compared to the rest of the USAF strategic bomber fleet has enabled it to continue to serve rather than be replaced by the Mach 3 XB-70 Valkyrie, B-1B Lancer and stealth B-2 Spirit. In January 2005, it was the second aircraft after the English Electric Canberra to mark 50 years of continuous use with its original primary customer.
The USAF Strategic Air Command had B-52 Stratofortresses in service from 1955 through 1991, when the aircraft were assigned to the Air Combat Command.

General characteristics

Crew: 5 (Pilot, Copilot, Radar Navigator (Bombardier), Navigator and Electronic Warfare Officer). Originally the B-52 had a crew of 6, with a Gunner sitting in the tail in all models up to the G. In the B-52 G/H, the Gunner position was moved to the front cockpit, with the gun remotely controlled.
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 ft� (370 m�)
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)
Fuel capacity: 47,975 US gal (181,725 L)
Powerplant: 8� Pratt & Whitney TF33-P-3/103 turbofans
Zero-lift drag coefficient: 0.0119 (estimated)
Drag area: 47.60 ft� (4.42 m�)


Performance

Maximum speed: 560 knots (650 mph, 1,000 km/h)
Combat radius: 4,480 mi (3,890 nm, 7,210 km)
Ferry range: 11,000 mi (8,099 nm, 15,000 km)
Service ceiling: 55,773 ft (17,000 m)
Rate of climb: 6270 ft/min (m/s)
Wing loading: 30 lb/ft� (150 kg/m�)
Thrust/weight: 0.51
Lift-to-drag ratio: 21.5 (estimated)


Armament

Guns: All models up to the H had a pod of four .50-caliber guns which could be loaded with armor-piercing/incendiary ammunition. The H model had one 6-barrel 20-mm Vulcan gatling cannon. The tail guns have now been removed on all operating B-52s.
Ordnance: up to 60,000 lb (27,200 kg) bombs, missiles, and mines, in various configurations



Stratofortress














The History of B-52 Stratofortress



Design and development

On 23 November 1945, Air Materiel Command issued desired performance characteristics for a new strategic bomber. The aircraft was to have a crew of five plus turret gunners plus a six-man relief crew. It had to cruise at 300 mph (240 knots, 480 km/h) at 34,000 ft (10,365 m) with a combat radius of 5,000 mi (4,340 nm, 8,050 km). The armament was to consist of unspecified number of 20 mm cannon and 10,000 lb (4,535 kg) of bombs. On 13 February 1946, the Air Force issued bid invitations for these specifications, with Boeing, Consolidated Aircraft, and Glenn L. Martin Company submitting proposals. On 5 June 1946, Boeing's Model 462, a straight-wing aircraft powered by six Wright T-35 turboprops with a gross weight of 360,000 lb (163,295 kg) and combat radius of 3,110 miles (2,700 nm, 5,010 km), was declared the winner. On 28 June 1946, Boeing was issued a letter of contract for US$1.7 million (1946 dollars, approximately US$17.5 million in 2006) to build a full-scale mockup of the new XB-52 and do some preliminary engineering and testing. However, by October 1946, the Air Force began to express concern about the sheer size of the new aircraft and its inability to meet the specified design requirements. In response, Boeing produced Model 464, a smaller four-engine version with a 230,000 lb (104,325 kg) gross weight, which was briefly deemed acceptable. Then, in November 1946, Curtis LeMay (who was serving as the Deputy Chief of Air Staff for Research and Development at the time) expressed the desire for a cruise speed of 400 mph (345 knots, 645 mph), to which Boeing responded with a 300,000 lb (136,080 kg) aircraft. In December 1946, Boeing was asked to change their design to a 4-engine bomber with a top speed of 400 mph, range of 12,000 miles (10,430 nm, 19,320 km), and the ability to carry a nuclear weapon. The aircraft could weigh up to 480,000 lb (217,725 kg). Boeing responded with two aircraft, both powered by the T-35 turboprops. The Model 464-16 was a nuclear-only bomber with a 10,000 lb payload, while the Model 464-17 was a general-purpose bomber with a 90,000 lb (40,825 kg) payload. Due to the cost associated with purchasing two specialized aircraft, the Air Force selected Model 464-17 with the understanding that it could be adopted for nuclear strikes.
When the updated requirements were formalized in June 1947, Model 464-17 met all of them except for the range. Furthermore, the entire project hinged on Curtiss-Wright's ability to deliver the T-35 engines. In the meantime, it was becoming obvious that even with the updated performance, the XB-52 would be obsolete by the time it entered production and would offer little improvement over the Convair B-36. As the result, the entire project was put on hold for six months. During this time, Boeing continued to perfect the design which culminated in Model 464-29 with a top speed of 455 mph (395 knots, 730 km/h) and a 5,000-mile range. In September 1947, the Heavy Bombardment Committee was convened to ascertain performance requirements for a nuclear bomber. Formalized on 8 December 1947, these called for a top speed of 500 mph (435 knots, 805 km/h) and an 8,000-mile (6,955 nm, 12,880 km) range, far beyond the capabilities of 464-29. The crew was reduced to a total of five and defensive armament was to be limited to the tail turret. The outright cancellation of the Boeing contract in December 1947 was staved off by a plea from its president William McPherson Allen, and in January 1948 Boeing was instructed to thoroughly explore all recent technological innovations, including aerial refueling and the flying wing. Noting stability and control problems Northrop was experiencing with their YB-35 and YB-49 flying wing bombers, Boeing insisted on a conventional aircraft, and in April 1948 presented a US$30 million (1948 dollars, US$250 million in 2006) proposal for design, construction, and testing of two Model 464-35 prototypes. Further revisions of specifications during 1948 resulted in an aircraft with a top speed of 513 mph (445 knots, 825 km/h) at 35,000 ft (10,670 m), range of 6,909 mi (6,005 nm, 11,125 km), and a 280,000 lb (127,000 kg) gross weight which included 10,000 lb of bombs and 19,875 US gal (75,225 l) of fuel.
The advent of more fuel efficient jet engines resulted in Boeing developing yet another revision � in July 1948, Model 464-40 substituted Westinghouse J40 turbojets for the turboprops. Nevertheless, on 21 October 1948, Boeing was told to create an entirely new airplane with Pratt & Whitney J57 turbojets. Remarkably, on 25 October, Boeing engineers produced a proposal as well as a hand-carved model of 464-49. The new design built upon the basic layout of the B-47 Stratojet with 35-degree swept wings, eight engines paired in four underwing pods, and bicycle landing gear with wingtip outrigger wheels. The aircraft was projected to exceed all design specifications. Although the full-size mockup inspection in April 1949 was generally favorable, range again became a concern since both the J40s and the early-model J57s had excessive fuel consumption. Despite some talk of another revision of specifications or even a full-out design competition among aircraft manufacturers, General LeMay, who by that time was in charge of Strategic Air Command, insisted that performance should not be compromised due to delays in engine development. In a final attempt to increase the range, Boeing created the larger 464-67, stating that once in production, the range could be further increased in subsequent modifications. Following several direct interventions by LeMay, on 14 February 1951, Boeing was awarded a production contract for 13 B-52As and 17 detachable reconnaissance pods. This was shortly followed by orders for four more B-52s and 43 reconnaissance RB-52s. The last major change in the design, also at the insistence of General LeMay, was a switch from B-47-like tandem seating to a more conventional side-by-side cockpit which increased the effectiveness of the co-pilot and reduced crew fatigue.
The YB-52 (actually, the second XB-52 with more operational equipment) first flew on 15 April 1952. The flight was largely uneventful. The XB-52 followed on 2 October 1952. The thorough development, including 670 days in the wind tunnel and 130 days of aerodynamic and aeroelastic testing paid off with smooth flight testing. Encouraged, Air Force increased its order to 282 B-52s.
The first production B-52A differed from prototypes in having a 21-inch (53 cm) nose extension to accomodate more avionics, a tail turret with four 0.50 in (12.7 mm) machine guns, and a water injection system to augment engine power with a 360 US gal (1,363 l) water tank in the rear fuselage. The aircraft also carried a pair of 1,000 US gal (3,785 l) external fuel tanks under the wings. At the rollout ceremony on 18 March 1954, General Twining said "The long rifle was the great weapon of its day. ... Today this B-52 is the long rifle of the air age."

Service

The B-52A first flew in August 1954 and the B model entered service in 1955. A total of 744 B-52s were built with the last, a B-52H, delivered in October 1962. Only the H model is still in the Air Force inventory and is assigned to the Air Combat Command and the Air Force Reserves.
The oldest B-52 still flying had been a B-52B, tail number 52-0008, that was built in 1955, though it also has the fewest flight hours of any surviving B-52. Nicknamed "Balls 8", it was operated by NASA's Dryden Flight Research Center and was famous for dropping such aerospace research vehicles as the X-15, X-24, HiMAT, lifting body vehicles, X-43, and others. It was the last B-52 in service of any type other than the H model. It had the lowest total air time of any operational B-52, and was the oldest active B-52 at the time, having first flown on June 11, 1955, and entering service with NASA in 1959. On July 30, 2001, Dryden received a B-52H to replace the older B-model, which was retired on December 17, 2004. Balls 8 will be preserved at Edwards' base museum.
The threat of B-52 attacks partially motivated the Soviet Union to back down from its plan to deploy nuclear-armed missiles (MRBMs) to Cuba in the 1962 Cuban Missile Crisis.
For carpet bombing duty in Vietnam, the B-52D received the "Big Belly" modification which squeezed 84 500-pound conventional bombs or 42 750-pound bombs into the bomb bay, as well as 24 750-pound bombs on each of the underwing pylons. Undersides were painted black to counter searchlights. B-52 raids which saturated large areas with heavy explosives had devastating effects on troop concentrations over South Vietnam. They were also used against strategic targets in the north, but were vulnerable to MiGs and SAMs.

G and H models

The G and H models have a shorter (by 8 feet) vertical tailplane. This configuration had previously been tested on a B-52A. The B-52H uses TF33-3 turbofan engines, which are visually different because of the fan section exhaust sections. They provide 20% greater range, 70% more thrust and are considerably quieter than the J57 engine which had been used on all previous variants. Turbofan engines use less fuel because the fans move unburned air as well as heated exhaust gases. The first of 102 of the B-52H model was delivered to Strategic Air Command in May 1961. The H model can carry up to 20 air launched cruise missiles (ALCMs). In addition, it can carry the conventional cruise missile that was used in several missions during the 1990s, starting with Operation Desert Storm and culminating with Operation Allied Force in the spring of 1999.

Alert Duty

A portion of the B-52 force was kept fueled, crewed, and loaded with nuclear weapons for take off on a few minutes' notice. The plan was to remove the aircraft from their bases, which would have been destroyed by incoming enemy missile warheads.
B-52s also performed airborne alert duty under the code-name "Chrome Dome" where bombers loitered near points outside of the Soviet Union. During this program a fatal collision occurred between a B-52 and a KC-135 over Palomares, Spain in 1966. Four megaton-range nuclear bombs were lost (all four were later recovered). Two of the four bombs had a minor detonation, as the warheads' conventional explosives were set off, with serious dispersion of both plutonium and uranium material. The main fuse safety withstood the violent impact and explosion, preventing a nuclear disaster.
After this crash thousands of tons of contaminated soil were sent to the US. The USAF decided this was too expensive to risk again and ended the airborne alert program. In 2006 an agreement to investigate and clean the pollution after the accident was made between the U.S. and Spain.
The 1973 Arab attack on Israel, and the subsequent threat of a Soviet invasion of Israel, brought the B-52s to their highest state of ground alert (see below).
In 1991 President George H.W. Bush ended an era when he took the B-52s off "alert" duty.

Combat Record

B-52s were used extensively in the Vietnam War (see Operation Arc Light) against the North Vietnamese Army. B-52s dropped bombs on suspected enemy arms caches and hideouts and were thought to have inflicted huge losses - but hard data pertaining to the results of many bombing missions with "dumb" bombs are scarce. The use of such unguided munitions has been phased out as it required very large expenditure of munitions and accuracy was questionable. In modern times, B-52s more commonly carry smart bombs such as the JDAM. in Vietnam war, a total of 25 B-52s were lost to soviet anti-aircraft missiles.
In the Battle of Khe Sanh, North Vietnam's plan to turn the Marine stronghold into another Dien Bien Phu was allegedly thwarted by round-the-clock B-52 strikes.
The zenith of B-52 attacks in Vietnam was Operation Linebacker II, which consisted of waves of B-52s (mostly D models, but some G's without their jamming equipment and with a smaller bomb load) bombing Hanoi. This was called "The Eleven-Day War". The objective was to force North Vietnam back to the Paris Peace Talks, which up to that point they had refused to do. In Linebacker II, fifteen B-52s were shot down, and in all, 25 were destroyed in combat during the war.
B-52D tail gunners were credited with shooting down two MiG-21 'Fishbeds'; one on December 18, 1972, by SSgt Samuel O. Turner, and one on December 24, 1972, by A1C Albert E. Moore. Turner was awarded a Silver Star for his actions.

After Vietnam

The Yom Kippur War in October 1973 saw the Soviet Union threaten to intervene on behalf of Egypt and Syria. To stop the Soviets, President Richard M. Nixon called on the military to raise its alert level to DEFCON 3. Secretary of Defense Melvin Laird ordered the B-52s to an immediate war footing. Fully armed and fueled B-52s were circling Greenland, round trips, round trip from USA to Europe, Northern Europe daily for years. The Soviet Union did not become directly involved in the war.
In 1982, the last B-52Ds were retired. The remaining G and H models were used for nuclear standby ("alert") duty (see above) as part of the United States' nuclear triad. This triad was the combination of nuclear-armed land-based missiles, submarine-based missiles and manned bombers. The B-1B Lancer, rather than completely replacing the B-52, replaced only the older models and the supersonic FB-111. The B-2 Spirit also accelerated the retirement of the B-52G models but did not lead to the B-52's total retirement either. In the 1960s, the Mach 3 B-70 was cancelled as more emphasis was placed on ICBMs, and the B-52 was given a conventional bombing mission.
After the fall of the Soviet Union, the B-52Gs were destroyed as per the terms of the Strategic Arms Reduction Treaty (START). Today only the H models remain in service.
High-altitude carpet-bombing by B-52s was an important part of the air war during Operation Desert Storm during the 1991 Persian Gulf War. Since the Coalition forces had complete air superiority and were able to suppress any air defense systems capable of reaching the high-altitude bombers, they could be employed with impunity. Though less destructive than more advanced weapons such as cluster-bombs or precision guided projectiles, the conventional strikes were used because they were economical, and it was hoped that by demoralizing the defending Iraqi troops, they could be induced to surrender rather than be destroyed.
The B-52 also contributed to the U.S. success in Operation Enduring Freedom in Afghanistan, providing the ability to loiter high above the battlefield and provide Close Air Support (CAS) through the use of precision guided munitions, a mission that had been restricted to fighter and ground attack aircraft. B-52's also played a key role in the second Gulf War in 2003 (Operation Iraqi Freedom), where they provided close air support and bombing.
The Air Force intends to keep the B-52 in service until around 2050, an unprecedented length of service for a combat aircraft model (the venerable DC-3, now 70 years old, is still in regular revenue service in civilian hands). This is especially remarkable considering that the last B-52 was built in 1962; the Air Force fully expects to be flying 90-year-old airframes. It is entirely possible that the B-52 may outlive both its replacements, the B-1 and B-2. Periodically, B-52s are rebuilt at the USAF's maintenance depots such as Tinker Air Force Base, Oklahoma. Therefore, despite their chronological age, their actual service age is quite young.Boeing has suggested re-engining of the B-52H fleet with the Rolls-Royce RB211 534E-4. This would involve replacing the eight Pratt & Whitney TF33s (total thrust 8 x 17,000 lb or 30.574 kN) with four RB211s (total thrust 4 x 37,400 lb or 33.191 kN). The RR engines will increase the range/payload of the fleet and reduce fuel consumption. However, the cost of the project would be significant. Procurement would cost approximately $2.56 billion ($36 million � 71 aircraft). A General Accounting Office study of the proposal concluded that Boeing's estimated savings of $4.7 billion would not be realized. They found that it would cost the Air Force $1.3 billion over keeping the existing engines.
The USAF continues to employ the B-52 because it remains an effective economical heavy bomber, particularly for the type of conflicts conducted since the end of the Cold War against nations with limited anti-air capabilities. The stealth and speed of the B-1 Lancer and B-2 Spirit have only been useful until enemy air defenses were destroyed, a task that has been swiftly achieved in recent conflicts. The B-52 boasts the highest mission-capable rate of the three types of heavy bombers operated by the USAF. Whereas the B-1 averages a 57% ready rate and the B-2 achieved a 26% in 1997 , the B-52 averages 80%.

Features

In a conventional conflict the B-52 can perform strategic attack, air interdiction, offensive counter-air and maritime operations. During Operation Desert Storm, B-52s delivered 40% of all the weapons dropped by coalition forces.
All B-52s are equipped with an electro-optical viewing system that uses platinum silicide forward-looking infrared and high resolution low-light-level television sensors to augment targeting, battle assessment, and flight safety. This improves its combat ability and low-level flight capability.
Pilots wear night vision goggles (NVGs) to enhance their vision during night operations. These goggles provide greater safety during night operations by increasing the pilots' ability to avoid terrain and enemy radar and to see other aircraft in a covert/lights-out environment.
In addition to its twin-tandem main wheels, B-52s have two small retractable "boogie wheels" near the outboard ends of the wings which are used during takeoff and when the aircraft is being taxied or is parked. These prevent the wing tips, which droop when the wing fuel tanks are filled, from brushing the ground.
Starting in 1989, ongoing modifications incorporate the Global Positioning System, heavy stores adapter beams for carrying 2,000 pound (900 kg) munitions, and a full array of advanced weapons currently under development.
The B-52 has an unrefuelled combat range in excess of 8,800 statute miles (14,000 km). The use of aerial refuelling from KC-135 or KC-10 tankers gives the B-52 a range limited only by crew endurance, or in the extreme, required maintenance. B-52s launching cruise missiles at Iraq flew from and returned to bases in the US.
The B-52 has an air-refueling receptacle above the cockpit hidden behind slip-way doors. Fuel can be transferred to the B-52 at a maximum rate of 6400 pounds (1000 gallons) per minut.
The crosswind crab system of a B-52 provides a means of turning all four main gear to align with the runway while the aircraft is flown in a wings-level attitude compensating for drift. This system uses the steering actuators on the front main gear and a similar set on the rear main gear. The landing gear can be preset and turned up to 20� left or right of center during the approach. The maximum of 20� crab will accommodate landings in crosswinds up to and including 43 knots blowing 90� to the runway at a landing weight of 270,000 pounds.
The aircraft is highly effective when used for ocean surveillance, and can assist the U.S. Navy in anti-ship and mine-laying operations. In two hours, two B-52s can monitor 140,000 square miles (364,000 km�) of ocean surface. This area is about as large as a circle centered at New York City and covered as far as Washington, DC, Syracuse and Boston (radius, equaling 212 statute miles or 340 km).
The aircraft's flexibility was evident in Operation Desert Storm and again during Operation Allied Force. B-52s struck wide-area troop concentrations, fixed installations and bunkers, and ruined the morale of Iraq's Republican Guard. The Persian Gulf War involved the longest strike mission in the history of aerial warfare when B-52s took off from Barksdale Air Force Base, Louisiana, launched conventional air launched cruise missiles and returned to Barksdale� a 35 hour, non-stop combat mission. During Operation Allied Force, B-52s opened the conflict with conventional cruise missile attacks and then transitioned to delivering general purpose bombs and cluster bomb units on Serbian army positions and staging areas.

Fuel research platform

In September 2006, the B-52 became one of the first US military aircraft to fly using 'alternative' fuel. Syntroleum, a leader in Fischer-Tropsch (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 plane. This marked the first time that FT jet fuel has been tested in a military flight demo, and is the first of several planned test flights.
On December 15, 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 has been 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 has 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.
This program is part of the DOD's Assured Fuel Initiative, an effort to develop secure domestic sources for the military's energy needs. The Pentagon hopes to reduce its use of crude oil and foreign producers and obtain about half of its aviation fuel from alternative sources by 2016.


sources:
http://aircraft-list.com/db/B-52_Stratofortress/42/
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