A Case Study of the Boeing B-47 Stratojet.ppt

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1、,A Case Study of the Boeing B-47 Stratojet,Joel Grasmeyer Troy JonesDana Horn Duane Knill,Outline,The political and economic climate The evolution of the B-47 B-47 innovations in aerodynamics, stability and control, and structures The legacy of the B-47,At This Time in History .,Its 1943 and World W

2、ar Two is raging Aircraft production in the U.S. is staggering Aircraft development is rapid Piston engine technology reaching limits Turbojet engines show promise Britain and Germany have advantage Reports of German fighter jets prompt U.S. to consider jet bombers,Origins of the B-47,Air Corps Desi

3、gn Competition, 1944 Design high speed jet bomber, 500 mph + 8,000 pound payload Range of 2,500 to 3,500 miles Service Ceiling of 40,000 feet Designs submitted in 1944 North American B-45 Convair B-46 Boeing B-47 Martin B-48,Evolution of the B-47,B-47 began as straight wing design Limited top speed

4、to under 500 mph Operation Paperclip Adolph Busemann Swept wing theory in 1935 Engines and more engines Fuselage and wing mounted Four or six?,Evolution of the B-47,Evolution of the B-47,Image from: The Politics of the U.S. Strategic Bomber ProgramMichael E. Brown, 1992.,The Production B-47,Images F

5、rom: American Warplanes, Bill Gunston, 1986.,Podded Engines on the Wing,Image From: American Warplanes, Bill Gunston, 1986.,Podded Engine Advantages,Interference drag was reduced in the wind tunnel Strut weight was minimal Increased span loading Reduced the wing root bending moment Reduced wing weig

6、ht Forward mass increases flutter resistance Increased accessibility for maintenance Increased passenger safety in case of an engine fire,Pitch-up Problems (Dana),Longitudinal Stability (Dana),The Yaw Damper (Dana),The Flexible Wing,Long range transonic cruise requirements: Large span for minimum in

7、duced drag (116 ft.) Thin airfoils for minimum wave drag (12%) This led to a very flexible wing The load distribution was shifted inboard at high gs This allowed an 8 ft. span extension at each tip without changing the original wing structure or engine locations Acted as a shock absorber to reduce g

8、ust loads,The Legacy of the B-47,The B-47 led directly to the development of the 707 Todays commercial transports follow the design paradigm of the B-47/707,Boeing 720 1960,Boeing 777 1996,References,Brown, Michael E., Flying Blind - The Politics of the U.S. Strategic Bomber Program. Cornell Univers

9、ity Press, London, 1992. Cook, William H., The Road to the 707, TYC Publishing, Bellevue, 1991. Donald, David, Ed. American Warplanes of World War II. Aerospace Publishing Limited, London 1995. Gunston, Bill, American Warplanes. Salamander Books, New York, 1986. Irving, Clive, Wide-Body: The Triumph of the 747, William Morrow, New York, 1993.,