1952: B-52 Stratofortress Goes Into Full-Scale Production
The B-52 Stratofortress
U.S. Air Force Orders the Eight-Jet Heavy Bomber
The Boeing B-52 Stratofortress, in service today, over 70 years after its first test flight, is one of the most versatile and successful aircraft ever designed.
Originally conceived as a replacement for the Convair B-36, with a long-range, high altitude, free-fall nuclear delivery mission, it has adapted over the years to changing technological and political conditions, assuming a wide variety of tasks and requiring tactics unforeseen by the engineers and airmen responsible for its design and procurement in the late 1940s.
Today, it is still flying and fighting, and will probably do so until 2040 or longer. One saying that is popular with today’s aircrews is:
“The last B-52 pilot hasn’t been born!”
Initial B-52 Design
The requirement for a heavy bomber with intercontinental range dates back to the darkest days of World War Two, when it was feared that England might fall and the bases it provided be lost, necessitating a transatlantic continuation of the war against Hitler.
Although not delivered until after the war, in 1948, the Convair B-36 was the eventual response to this requirement, and to the previously unforeseen challenge posed by the Soviet Union.
By the time it entered service, however, technology—especially the emergence of jet fighters—had already dictated its early obsolescence, and the requirement for its replacement had already been stated in early 1946, calling for an unrefueled range of 8000 miles with a 10,000 lb bomb load and a top speed of 450 mph.
A preliminary design contract was awarded to the Boeing Company that year. Boeing had earned an impressive reputation and considerable expertise in the heavy bomber field with its highly successful B-17s and B-29s.
Initially, both Boeing and the Air Force envisioned this second generation intercontinental bomber as a turboprop, since pure jet development had not yet produced an engine powerful enough, and because the turboprop was more fuel efficient, translating into greater range. The company was, in fact, working on a jet-powered medium bomber—the B-47—but its smaller size and expected performance did not satisfy the new requirement.
The design with which Boeing won this new contract was a conventional one, essentially a B-29 scaled up to B-36 size with straight wings and six turboprop engines.
By the Fall of 1948, a number of refinements to this original design had been made, but the projected performance was still not much better than that of the improved B-36 it was to replace.
Then, several events changed the course of its development.
- The company responsible for the engine intended for the aircraft had encountered difficulties in its development, causing the program to fall behind.
- Concurrently, the Pratt and Whitney Company was making unexpected progress with a new jet engine, the J-57, with 10,000 lbs of thrust, a significant advance.
- Finally, the potential of in-flight refueling was greatly increased with the development of the “flying boom” by Boeing. This rendered the fuel savings of the turboprop less critical.
During a visit by senior Boeing officials to Wright-Patterson AFB to review progress, the Air Force chief of bomber development asked the Boeing team to look at the possibility of substituting pure jet power.
This was on Thursday, 21 October 1948. By coincidence, the Boeing staff present that weekend included just the right combination of skills and knowledge to respond to this opportunity.
Closeting themselves in a Dayton hotel room, with an open line back to the engineering staff and analysts in Seattle, they hammered out a new design which was surprisingly like the prototype which was to roll out of the factory some three years later.
This was submitted to the Air Force on Monday, and the B-52 as it flies today was truly born.
Equally responsible for the dramatic change in direction of the B-52 design was the unexpected success Boeing was having with the independent development of the B-47 medium bomber.
The B- 47 had used essentially off-the-shelf technology in a radical design which incorporated two World War Two innovations:
- the jet engine
- the swept wing
Flight testing going on at that time was revealing accomplishments beyond all expectations in reducing drag. The confidence instilled by this success encouraged Boeing engineers to push the technology envelope with the B-52.
One lesson learned was that the thin wing used on the B-47 for stability at transonic speeds was not essential, allowing the new design to include a tapered wing—thick and wide at the root, thin and flexible further out—and a greatly enlarged wing area.
This, combined with major weight savings throughout, resulted in a very high lift over drag ratio, the major factor in the continuing growth potential of the aircraft.