Dueling bombers

Boeing's YB-52 beat out Convair's YB-60—and continues to serve

BY ERIK SIMONSEN

With an unmistakable drone produced by its six pusher-mounted piston engines (and four J47 jet engines), the massive Convair B-36 Peacemaker was the mainstay of the United States' long-range bomber force during the late 1940s and early 1950s. But the Peacemaker's days were numbered as U.S. adversaries modernized their air-defense systems. As early as 1946, the Air Force recognized the need to eventually develop a fast intercontinental-range bomber. Initially, planners thought turboprops offered the best solution, which would sacrifice speed for range.

Although there was never an official Air Force fly-off, Boeing and Convair went head-to-head demonstrating bomber prototypes (a Douglas turboprop–powered proposal never moved off the drawing boards).

With the B-36 production line in place at its facility in Fort Worth, Texas, Convair felt it had a lower-cost solution. A transition production plan called for a jet-powered (YB-36G) variant to follow the B-36F, if a new Air Force contract could be secured. The new aircraft would have 72 percent parts commonality with the B-36.

Convair submitted an unsolicited proposal on Aug. 25, 1950. On March 15, 1951, the Air Force authorized a contract to convert two partially completed B-36s to a jet-powered configuration. The No. 1 aircraft received an Air Force designation of YB-60, and the No. 2 with production features would be the B-60.

With its B-47 medium-range jet bomber operating with Strategic Air Command, Boeing decided to compete and assembled a top design team. Boeing designers Well Beall, George Schairer and Ed Wells formed the core of the Boeing team. The original design (Model 462) looked like an uprated six-engine B-29, which by October 1948 evolved into a swept-wing turboprop configuration (Model 464-35), similar to the Russian Tu-95 "Bear."

After meetings with Air Force officials, the Boeing offering evolved into a jet-powered design with a 20-degree wing sweep and predicted top speed of 500 mph. Advised to give the design more speed, the Boeing team—which added Bob Withington, Vaughn Blumenthal, Art Carlsen and Maynard Pennell—came up with the right solution: a 35-degree sweep and eight Pratt & Whitney J57 jet engines. During the final meeting, the team presented its 33-page report, along with a hastily produced balsawood model (which today resides in the Boeing archives). The design was ultimately accepted by the Air Force, and Boeing was authorized to build two aircraft, the XB-52 and YB-52. Estimated top speed was more than 600 mph with a range far greater than that of the B-47's.

On the surface, it seemed like a close race. The YB-52 made its first flight on April 15, 1952, and just three days later at Convair's Fort Worth facility the YB-60 was airborne. Most notable on the YB-52/XB-52 was the tandem seat cockpit. The B-52A and subsequent variants featured a conventional flight deck with side-by-side seating.

Initial reports on the YB-52 were extremely promising, substantiating the design's jet-powered flight dynamics, which included spoilers acting as ailerons. This strategy proved its worth, as the aircraft's performance ultimately secured the win for Boeing. At Convair, modifying the B-36 airframe and achieving the desired performance was not as simple as first imagined. The wing was swept at 37 degrees and the thickness of the wing chord, inherited from the B-36, allowed for 10 fuel tanks holding 42,106 gallons of fuel—but at a cost of substantially increased drag. Additionally, high aerodynamic forces on a flight control system originally designed for slower airspeeds degraded performance considerably.

After its initial ferry flight to the Edwards Air Force Base Flight Test Center in California, the YB-60 flew 25 sorties and accumulated approximately 83 hours of test flight time. The second aircraft (B-60) was to be closer to a production configuration and featured a more aerodynamic nose that, if it had flown, would have increased airspeed. However, the Air Force ordered the B-52 into production in December 1952 and announced cancellation of the B-60 program the following January. The YB-60 and the 95-percent-completed B-60 were both scrapped.

Each subsequent model of the B-52 resulted in dramatic improvements to the bomber's structure and internal systems. Ready to operate in a network-enabled environment, the current B-52H continues to serve the Air Force today—and will for decades to come.

erik.simonsen@boeing.com