United States Department of Defense - B-52 Stratofortress

The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered, strategic bomber flown by the United States Air Force (USAF) since 1955.

Beginning with the successful contract bid on 5 June 1946, the B-52 went through several designs, from a straight wing aircraft powered by six turboprop engines, to the final prototype, YB-52 (with 8 engines), which first flew on 15 April 1952 by "Tex" Johnston.

Built to carry nuclear weapons for Cold War-era deterrence missions, the B-52 Stratofortress replaced the Convair B-36. Although a veteran of a number of wars, the Stratofortress has dropped only conventional munitions in actual combat. With the longest unrefuelled range of any contemporary bomber, the B-52 carries up to 70,000 pounds of weapons.

The USAF has had B-52s in active service since 1955 with Strategic Air Command and were later absorbed into Air Combat Command in 1992. Superior performance at high subsonic speeds and relatively low operating costs have kept the B-52 in service despite proposals to replace it with the Mach 3 XB-70 Valkyrie, supersonic B-1B Lancer and stealthy B-2 Spirit. In January 2005, the B-52 became the second aircraft, after the English Electric Canberra, to mark 50 years of continuous service with its original primary operator.

On 23 November 1945, Air Materiel Command (AMC) issued desired performance characteristics for a new strategic bomber "capable of carrying out the strategic mission without dependence upon advanced and intermediate bases controlled by other countries".The aircraft was to have a crew of five plus turret gunners, and a six-man relief crew. It had to cruise at 300 Miles per hour (240 kn, 480 km/h) at 34,000 feet (10,400 m) with a combat radius of 5,000 statute miles (4,300 nmi, 8,000 km). The armament was to consist of an unspecified number of 20 mm cannon and 10,000 pounds (4,500 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 pounds (160,000 kg) and combat radius of 3,110 statute miles (2,700 nmi, 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) to build a full-scale mock-up of the new XB-52 and do 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 pound (105,000 kg) gross weight, which was briefly deemed acceptable.

Then, in November 1946, the Deputy Chief of Air Staff for Research and Development Curtis LeMay expressed the desire for a cruise speed of 400 miles per hour (345 kn, 645 km/h), to which Boeing responded with a 300,000 pound (140,000 kg) aircraft. In December 1946, Boeing was asked to change their design to a four-engine bomber with a top speed of 400 miles per hour, range of 12,000 statute miles (10,000 nmi, 19,000 km), and the ability to carry a nuclear weapon. The aircraft could weigh up to 480,000 pounds (220,000 kg). Boeing responded with two models powered by the T-35 turboprops. The Model 464-16 was a "nuclear-only" bomber with a 10,000 pound payload, while the Model 464-17 was a general purpose bomber with a 90,000 pound (40,000 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 adapted for nuclear strikes.

In June 1947 the military requirements were updated and the Model 464-17 met all of them except for the range. It was becoming obvious to the Air Force 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 resulted in the Model 464-29 with a top speed of 455 miles per hour (395 kn, 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 miles per hour (440 kn, 800 km/h) and an 8,000 statute mile (7,000 nmi, 13,000 km) range, far beyond the capabilities of 464-29.

The outright cancellation of the Boeing contract on 11 December 1947 was staved off by a plea from its president William McPherson Allen, and in January 1948 Boeing was instructed to thoroughly explore 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) 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 miles per hour (445 kn, 825 km/h) at 35,000 feet (10,700 m), a range of 6,909 statute miles (6,005 nmi, 11,125 km), and a 280,000 pounds (125,000 kg) gross weight which included 10,000 pounds of bombs and 19,875 US gallons (75,225 L) of fuel.