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June 2006 |
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Volume 05, Issue 2 |
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Historical Perspective |
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Dueling bombers Boeing's YB-52 beat out Convair's YB-60—and continues to serve BY ERIK SIMONSEN
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."
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.
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