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Aviation History
1948
1948 - 1987.PDF
. - The business end of the Northrop YB-49. Some 32,000 Ib of thrust is exerted through the eight nozzles. ; ALL-|ET BOMBER AIR FORCE? U.S. Air Policy and Bomber Development THE question-mark on the signpost suggests thatbefore dismissing the piston-engined bomber asdemode in favour of the pure jet, there may be a middle road worth exploring. In England this middle course is finding fruition in the turboprop combination, whereas in America the piston-turbo compound engine has made bigger strides. The two important gains of com- pounding are a substantial increase in power and a 20 per cent reduction in specific fuel consumption—albeit obtained at the expense of further mechanical complexity. The Pratt and Whitney Wasp Major, for example, is boosted from 3,500 to 4,000 h.p. for take-off, and from 2,800 to 3,880 h.p. at 30,000ft. This variable discharge turbine model, designated the R-4360-VDT, will power the Boeing B-54 (formerly the B-50C), and may be expected to raise the top speed to 460 m.p.h. at 30,000ft, and to stretch the range about 25 per cent. American designers, of course, have also seriously studied the long-range potentialities of the turboprop bomber, although the only production engine of that type currently available appears to be the Wright T-35 Typhoon, delivering about 5,000 s.h.p. It is possible that the Boeing XB-52, a 400,000 lb Superfortissimo, has been Anatomy of t/ie Northrop YB-49, with turbojets and a maximum bpmb-^load By "FAVONIUS" tentatively designed around this engine; also the Martin XB-51 and Convair XB-53, probably to the same U.S.A.F specification. Northrop, also, were reported interested in a turbopropped all-wing bomber projected around their own XT-37 Turbodyne engine, which has recently developed about 7,400 s.h.p. Most of these projects, however, seem to be back in the archives—with resulting economy, no doubt, to the American taxpayer. We hope to show that all this middle road exploration is a detour off the strato- spheric highway, which leads back to the turbojet for short-, medium- and even long-range bombing. - • ; Northrop B-49 ^ As mentioned previously, the YB-49 is the jet-powered derivative of the B-35. Two of these jets have so far been built and flown, one of which recently blew up in the air and was totally destroyed. Nevertheless, increasing Air Force confidence in the type is indicated by the fact that a further batch of 30 is currently on order, -while the remaining YB-35S may also be converted into jets. Further, it is known that negotiations are proceeding for even more substantial quantities from 100 to 500. A high priority is implied by the announcement that the majority of these will be sub-contracted by Northrop for production at the Fort Worth, Texas, plant of Consolidated-Vultee, where they will be built alongside the Convair B-36. The latter firm, although they have vastly bigger production facilities available, did not receive any plums in the shape of original design awards from the new rearmament programme. The B-49 mounts eight Allison J-35 axial- compressor turbojets, producing a combined static thrust of 32,000 lb. At the respective This is the concluding article in a series of three, reviewing the aircraft authorized under the U.S.A.F. 70-group Rearmament Policy. Previous articles appeared in " Flight," June 10 and October 21, 1948.
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