B-49 Flying Wing
The Northrop YB-49 was the jet-propelled variant of the company's XB-35 bomber. Eight Allison J35 engines, each delivering 3,750 pounds of thrust, gave the flying wing a top speed of 510 mph, or more than 100 mph faster than its prop-driven predecessor. The YB-49 had great promise, but flight testing soon revealed that it also had a lot of things wrong with it. Most prototypes do, particularly those designs that push hard against the boundaries of aeronautical possibilities. Many of the YB-49's problems lay in its engineering design, and the compromises necessary in converting a piston engine design to jet propulsion. Some of these problems could have been corrected, but others could not be.
The concept of a jet powered flying wing offered many possibilities: increased range and speed for the same power; more efficient airframe; substantial weight-lifting capability; and smaller aircrew. Its payload could be distributed evenly along the entire span, eliminating heavy internal bracing. Similarly, bomb bays no longer had to be confined to a narrow fuselage tube, but could be spread across the underside of the wing. From a strictly design standpoint, these advantages are indisputable.
The Flying Wing's basic airfoil section might have been optimum for the XB-35, but was clearly inadequate for the higher speeds needed for a jet bomber. Thus, the YB-49 cruised nearly 100 mph slower than the XB-47. The XB-35 never achieved its hoped-for bomb load, and its jet derivative fared no better.
Even worse, the bomb bays were simply too small for the nuclear weapons of the day. The cockpit layout was horrible: the pilot had a one-man bubble affording good visibility, but it could not be opened. There were no ejection seats. To leave his position, the pilot had to rotate his seat 90 degrees, lower it several feet, and walk to a hatch 15 feet away. The co-pilot's position was buried in the leading edge; he had a very poor view that prevented him from taking off or landing the aircraft.
Flight testing revealed stability problems which could not be corrected with existing technology. The designers had not been able to anticipate the critical control requirements needed for a large all-wing airplane, especially for a system that could anticipate and correct problems before the pilot was aware of them. That, of course, would have to wait for the computer age. The Air Force's flight evaluators soon found that the YB-49 was sloppy in turns, and took too long to steady up for an effective bombing run. The YB-49 was a sleek airplane, its upper surfaces marred only by four wing fences and small auxiliary fins added for greater control. Wing fences were added to the YB-49 to control the spanwise movement of air toward the wingtips [today's electronic stability augmentation systems would have made them unnecessary]. Its 1940s control technology was inadequate to the big plane's needs. Worse, it could not provide the necessary margin of flight safety.
In May 1948, Capt. Glen W. Edwards was selected to join the team of test pilots and engineers at Muroc who were then evaluating the Northrop YB-49, the all-jet version of the exotic flying wing bomber. After his first few flights, he was not favorably impressed, confiding to his diary that it was "the darndest airplane I've ever tried to do anything with. Quite uncontrollable at times." Then, on June 5, 1948, he was flying as co-pilot with Maj. Daniel Forbes when the airplane departed from controlled flight and broke apart in the sky northwest of the base. All five crewmembers were lost.
One of Col. Albert Boyd's first orders of business, when he assumed command of Muroc in late 1949, was to rename the base in honor of someone who had given his life to the cause of experimental flight research. By tradition, Air Force bases were named after distinguished individuals who were native sons of the state in which a base was located. Boyd could think of no one more deserving than the bright young Californian whose promising career had ended so tragically in the skies over the western Mojave. On Dec. 8, 1949, Muroc Air Force Base was officially redesignated Edwards Air Force Base and, during ceremonies on Jan. 27, 1950, a plaque was unveiled which commemorated his achievements. That plaque is now located in a place of honor in front of the headquarters of the Air Force Flight Test Center. The tribute at its base reads: "A pioneer of the Flying Wing in the western skies, with courage and daring unrecognized by himself."
After this crash of the second YB-49, the first aircraft was modified with additional flight performance measuring instruments before tests were resumed. On March 15, 1950, an Air Force crew was testing the aircraft stabilizer response during a high speed taxi run when the nose wheel began a violent shimmy. Before the aircraft could be brought under control, the nose landing gear collapsed and the No. 1 YB-49 broke in two and was destroyed.
The Northrop Corp. proposed a modification to the YB-49 Flying Wing bomber, called the YRB-49A. One YB-35A was modified with six jet engines and became the YRB-49A. Although its small radar signature had been noticed during tests during the late 1940s, it was the YB-49's high altitude and long-range flying abilities that gave it consideration as a spy plane. The plane promised a 400-mph cruise speed at 35,000 feet. The photo reconnaissance variation of the bomber which was tested late in the program. The YRB-49A carried two of its six jet engines in pods below the wing, making room for more fuel. The aircraft was designed for the photo reconnaissance role and had camera equipment installed in the center and aft fuselage. The aft lower center fuselage was also modified for a radar navigation system with an extensive external modification required for the radome, and the gunner's bubble was also deleted. The YRB-49A made its first flight on May 4, 1950. A brief test program of only thirteen flights was conducted before the aircraft was put into storage in late 1950. The aircraft was flown one more time on 26 April 1951 from short term storage facilitiies at Edwards AFB to long term storage at Northrop's Ontario airport (California) facilities. The YRB-49A sat until it was scrapped in late 1953.
The program was canceled by the Air Force in 1949. Popular folklore among aviation enthusiasts holds that Northrop's futuristic Flying Wing was a wonder plane which was smothered in its cradle - a jet-powered marvel of fantastic performance which could have revolutionized postwar aviation "if only" it had been given a fair chance. The fact that the plane was canceled amid rumors of high-level conspiracy, and replaced by the more conventional - if equally awesome - B-36, only added to the legend. The last flight of the last Wing took place on 26 April, 1951. Eighteen months later, Northrop had resigned from Northrop Aircraft, Inc., and left the aviation industry. The entire run of XB-35s and YB-49s was dismantled. None of the airframes were saved for museums or display purposes. The last aircraft (YRB-49A) was scrapped in November 1953.
Perhaps it is fair to say that Northrop's design concepts were solid, but the means to implement them were still several decades away. The YB-49 was simply a generation ahead of its time. The YB-49 was the "wrong plane at the wrong time," getting trapped in the transition between propeller-driven and jet-powered aircraft.
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