The B-47A (49-1900) bomber was the first to be built at the Boeing Aircraft Company in Witchita, Kansas. NACA High-Speed Flight Research Station obtained that B-47A Stratojet (NACA 150) to study the characteristics of a large, flexible swept-wing aircraft in 1953.
|DFRC Photo #
||B-47A Stratojet Photo Collection Contact Sheet
||July 14, 1954
||Stan Butchart climbing into B-47
||August 12, 1953
||B-47A landing with drag chute
||August 12, 1953
||B-47A on ramp
||September 17, 1954
||B-47A on ramp with crew, pilots Stan Butchart and Joe Walker
||NACA Aircraft Fleet on lakebed - D-558-II and B-47A
||NACA Aircraft in hangar 1952 - L-R: Three D-558-IIs, D-558-1, B-47, and the wing of YF-84A. Background are the X-4 and F-51
||NACA Aircraft in hangar 1952 - clockwise from front center: YF-84A, D-558-I, D-558-II, B-47, X-1 ship 2, and XF-92A. Behind the B-47 L-R: X-4, F-51, D-558-I, and X-5
NACA laboratories had an interest in the B-47A NACA 150; Langley Memorial Laboratory wished to study the impact of aeroelasticity upon structural loads and Ames Aeronautical Laboratory, the impact of aeroelasticity upon dynamic stability. Operation of the aircraft from either Center was not practical because of runway length. Accordingly the B-47A NACA 150 was sent to NACA High-Speed Flight Research Station at Edwards, where it flew from May 1953 to 1957.
In the past the response to control-surface motions had been fairly well established for a relatively rigid airplane by flight test and theory. However, in the mid 1950s the desire to increase the range and speed of large airplanes led to sweptback wings of high aspect ratio, thin airfoils, and fuselages of high fineness ratio. All of these factors tend to increase the flexibility of the structure and the associated aeroelastic effects which were becoming of greater importance in problems of static and dynamic stability and control. The dynamic effects were especially important in the design of automatic control systems because structural modes could introduce instabilities which would not arise with a rigid airplane.
The B-47A Stratojet did not have any apparent problems when it arrived at NACA but the testing revealed some serious design deficiencies; in particular, buffeting problems limited the plane's speeds and certain lift values. The B-47A testing resulted in reports that gave engineers and design teams around the country access to reliable information on the dynamic behavior and response characteristics that could be expected of large, flexible sweptwing airplanes, such as the Boeing KC-135 and the B-707 transport.