Designing the B-52
‘The most formidable expression of air power in the history of military aviation” was how Air Force Secretary Donald A. Quarles described the B-52. “Its range, which can be augmented by refueling techniques, its bomb load, its highly skilled crews, coupled with electronic equipment which makes it possible to find and hit any target anywhere in the world in any weather, constitute a weapons system which no other nation can match.”
When that evaluation was made in 1955, American bombers looked back on some 38 years of continuous development, each type being succeeded by a better one in a few years. No one imagined that B-52s would retaliate 46 years later against a terrible attack from an enemy not yet visible in 1955.
Boeing’s Stratofortress was to serve in front-line squadrons longer than any other USAF type, although its combat experience was to be very different than expected. The B-52 was designed to carry H-bombs, and the first thermonuclear weapon to be dropped from an American plane was a Mk 15 released from a B-52B on May 21, 1956, at Bikini Island. Its intended mission was to deter any such attack on America.
The B-52 story starts with an Army Air Force requirement dated November 23, 1945, for a heavy bomber with a 5,000-mile operating radius with a 10,000-pound bomb load and a 300-mph speed at 34,000 feet. Boeing, Convair and Martin responded to a Request for Proposals made February 13, 1946. Boeing’s Model 462, a 180-ton project incorporating six 5,500-hp Wright XT35 turboprops on a straight, 221-foot span, wing won a design contract on June 28, 1946.
Engineers began another struggle to combine long range with speed, and many revisions were made before Boeing offered another concept, Model 464-29 with four turboprops, 20 degree sweepback, and a 445 mph estimate. But Air Force doubts that any propeller-driven bomber could meet its performance goals almost caused the project’s cancellation, despite more revisions. Boeing engineers led by Edward Welles and George Schairer were called to AMC headquarters at Wright Field to defend their project. Learning that Pratt & Whitney was working on a new XJ57 jet engine, the Boeing men quickly produced a design in their Dayton hotel based on their XB-47 experience.
This configuration, Model 464-49, with eight J57s paired on pods suspended below a wing swept back 35 degrees, was presented October 27, 1948. Impressed, the Air Force approved a contract for two XB-52 prototypes on November 17. After mockup approval in April 1949, construction of the prototypes proceeded.
Meanwhile, Boeing also offered a propeller-driven Model 474 to the USAF in 1948. Powered by four 5,643-hp Allison T40-A-2 turboprops slung below a slightly swept high wing, and designated XB-55, the 153,000-pound design had twelve 20-mm guns in three turrets. Since only 490 mph was expected from the six-bladed contrarotating propulsion, the XB-55 was abandoned in favor of the faster turbojet B-52 layout. A four turboprop bomber, called the Bear, was very successful in Soviet service.
Although identical in appearance to the first XB-52, the second prototype was designated YB-52 for fiscal reasons. On April 15, 1952, it was first flown from Seattle’s Boeing field by A.M.“Tex” Johnson and Lt Col. Guy M. Townsend. The XB-52’s flight was delayed by mechanical problems until October 2. Both aircraft had a narrow canopy over tandem pilot seats, four pairs of main wheels retracting into the fuselage, small outrigger wheels at the wing tips, and a tall fin.
Eight YJ-57-P-3s were paired below the 36.5-degree swept wings whose airfoil sections had been developed in Boeing’s own wind tunnel. Neither the Sperry K-1A bombing system intended to go under the nose nor the radar-aimed two .50-caliber guns in the tail were ever installed in the prototypes.
Boeing’s competitor in jet-bomber development, was Convair’s Fort Worth factory, which became part of General Dynamics in 1953. Convair had proposed a B-36G on August 27, 1950, using 72 percent of the older type’s parts, but with a 37-degree swept wing and tail. On March 5, 1951, the Air Force ordered that two prototypes be modified from production B-36s and redesignated YB-60.
Eight J57-P-3 jets were paired in pods, like those of the B-52, and fuel capacity increased. While the 72,000-pound bomb capacity remained, all the turrets were omitted except for the twin 20-mm guns in the tail. Five crewmen sat in the pressurized front cabin, with a K-3A bombing-navigation system in the nose and APG-32 radar fire control for the gunner. An instrument probe protruded from the bow, but no ordnance was actually installed on the prototypes.
On April 18, 1952, three days after the YB-52, the YB-60 was first flown by Beryl Erickson. But since the YB-60 was much slower than the B-52, it did not replace the B-36 on Fort Worth production lines. On August 14, 1952, the B-60 program was canceled, and the second prototype left unfinished. Instead, Convair was left free to concentrate on designing the world’s first supersonic bomber.
Building the B-52
Boeing’s first contract for 13 production B-52s, approved December 16, 1952, introduced side-by-side pilots’ seats demanded by General LeMay. Provisions for two 1,000-gallon drop tanks, inflight refueling, and J57-P-1W engines with water injection were added. Four .50-caliber M-3 tail guns with A-3A radar fire control, as well as a chaff dispensing system, provided rear defense.