A Case Study of the Boeing B-47 Stratojet - Virginia Techmason/Mason_f/b47.pdf · A Case Study of...
Transcript of A Case Study of the Boeing B-47 Stratojet - Virginia Techmason/Mason_f/b47.pdf · A Case Study of...
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A Case Study of the A Case Study of the Boeing BBoeing B--47 Stratojet47 Stratojet
Joel Grasmeyer Troy JonesDana Horn Duane Knill
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OutlineOutline
u The political and economic climateu The evolution of the B-47u B-47 innovations in aerodynamics, stability and
control, and structuresu The legacy of the B-47
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At This Time in History ...At This Time in History ...
u It’s 1943 and World War Two is ragingu Aircraft production in the U.S. is staggeringu 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
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Origins of the BOrigins of the B--4747u Air Corps Design 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
u Designs submitted in 1944– North American B-45– Convair B-46– Boeing B-47– Martin B-48
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Evolution of the BEvolution of the B--4747u B-47 began as straight wing design
– Limited top speed to under 500 mph
u Operation Paperclip– Adolph Busemann– Swept wing theory in 1935
u Engines and more engines– Fuselage and wing mounted– Four or six?
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Evolution of the BEvolution of the B--4747Model # Date Wing Engines
413422
Jan. 1944early 1944
StraightStraight
4 Turbojets4 Turboprops
424,425426
early 1944early 1944
StraightStraight
4 Turbojets4 Turboprops
432446
Dec. 1944Sept. 1945
StraightSwept
4 Jets in Fuse.4 Jets in Fuse
448448-2-2
Sept. 1945Sept. 1945
SweptSwept
6 Jets in Fuse.6 Jets in Fuse.
450 Oct. 1945 Swept 6 Jets under wings
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Evolution of the BEvolution of the B--4747
Image from: The Politics of the U.S. Strategic Bomber ProgramMichael E. Brown, 1992.
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The Production BThe Production B--4747
Images From: American Warplanes, Bill Gunston, 1986.
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Podded Engines on the WingPodded Engines on the Wing
Image From: American Warplanes, Bill Gunston, 1986.
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Podded Engine AdvantagesPodded Engine Advantages
u Interference drag was reduced in the wind tunnelu Strut weight was minimalu Increased span loading
– Reduced the wing root bending moment– Reduced wing weight
u Forward mass increases flutter resistanceu Increased accessibility for maintenanceu Increased passenger safety in case of an engine fire
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PitchPitch--up Problems (Dana)up Problems (Dana)
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Longitudinal Stability (Dana)Longitudinal Stability (Dana)
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The Yaw Damper (Dana)The Yaw Damper (Dana)
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The Flexible WingThe Flexible Wing
u Long range transonic cruise requirements:– Large span for minimum induced drag (116 ft.)– Thin airfoils for minimum wave drag (12%)
u This led to a very flexible wingu The load distribution was shifted inboard at high g’s
– This allowed an 8 ft. span extension at each tip without changing the original wing structure or engine locations
u Acted as a shock absorber to reduce gust loads
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The Legacy of the BThe Legacy of the B--4747
u The B-47 led directly to the development of the 707u Today’s commercial transports follow the design
paradigm of the B-47/707
Boeing 7201960
Boeing 7771996
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ReferencesReferences
u Brown, Michael E., Flying Blind - The Politics of the U.S. Strategic Bomber Program. Cornell University Press, London, 1992.
u Cook, William H., The Road to the 707, TYC Publishing, Bellevue, 1991.
u Donald, David, Ed. American Warplanes of World War II. Aerospace Publishing Limited, London 1995.
u Gunston, Bill, American Warplanes. Salamander Books, New York, 1986.
u Irving, Clive, Wide-Body: The Triumph of the 747, William Morrow, New York, 1993.