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Aviation History
1954
1954 - 1877.PDF
844 FLIGHT Boeing B-50D (four Pratt and Whitney R-4360-35). Military Aircraft 1954 Bombers MEDIUM & HEAVY character all its own. The fuselage, in particular, is a relatively box-like structure and the wing is disproportionately greater in area than that of the B-47. Power plants are eight Pratt and Whitney J57s, in paired, underslung pods. When the B-52 design was analysed in Flight of December 5th, 1952, it was remarked that the wing represented the solution to an extremely difficult set of design criteria, and that while a delta would undoubtedly have been a much easier structural pro position, the Boeing designers elected to pin their faith on "the devil they knew"—*hat is, a heavily loaded structure of extreme flexibility. The span is 189ft, aspect ratio about 9, and area about 4,000 sq ft. As on the B-47, sweepback is 35 deg. Skinning is of very heavy gauge, and no stress wrinkles appear in flight (as they most certainly do on me 156ft fuselage). Nevertheless, flexibility is very high?—sufficient, in fact, to cause the ground anhedral angle of several degrees to become, at the tips, very noticeably dihedral in level flight. Angle of incidence is at least 7 deg, and thickness/chord ratio over 12 per cent at the root, though the remainder of the wing is much thinner. All primary bending loads—other than those taken by the skin—appear to be absorbed by a massive single spar at 50 per cent chord, stretching unbroken to the tip. A secondary spar further aft carries the flaps, but the remaining structure seems to consist solely of numerous chordal members normal to the leading edge. The main spar and the thick skin thus form a torsion-box to carry the very considerable twisting loads. Flaps are of modified Fowler type, and their inner sections move in towards the fuse lage as they are lowered. The vast vertical tail surfaces are hinged to fold to starboard, where they lie parallel with the tailplane. The unorthodox nature of the control system (which is manu ally operated), results from a number of abnormal and stringent demands. For instance, failure of the outer engine on one side of the aircraft could impart a yawing moment of unprecedented magnitude. Moreover, the structure, as we have already said, is unusually flexible. The ailerons—each of which can move up or down independ ently—appear to be small surfaces mounted between the flaps; further lateral control is probably obtained by means of large spoilers mounted on the wing upper surface at about 65 per cent chord. It seems likely that the trailing-edge ailerons are used for normal purposes and are backed up by one or more sections of spoiler for emergencies. The spoilers act both by increasing drag and by destroying lift, and are probably brought into play in the case of engine failure (resulting in yawing) as well as in rapid rolling manoeuvres. The rudder is of astonish ingly small proportions and is more akin to a trailing-edge tab, set in the vast fin. The undercarriage is of "double bicycle'' type, the port units retracting inwards and forwards, and the starboard units inwards and to the rear. Gross weight, originally quoted as "over 300,000 lb," is now known to exceed 350,000 lb. Range may already be over 6,000 miles and might eventually be extended to 10,000 miles without recourse to flight refuelling. Although the prototypes have no provision for assisted take-off, liquid-fuel rockets may be provided for the possible 250 production machines. A 35ft braking para chute is standard equipment. Production B-52As (the first of which left Boeing's Seattle plant in March) have side-by-side seating for pilot and co-pilot, in a largely redesigned nose, and carry external fuel tanks be neath the wing, beyond the outermost jet pods. Boeing B-50D. The B-50D is probably the last piston- engined bomber to which we shall have occasion to refer in this series of reviews. Its all-round efficiency is probably consider ably higher than that of the Russian Tu-4 (a copy of the B-29 from which the B-50 was developed); top speed is in the region of 400 m.p.h. at 25,OOOft, ceiling about 40,000ft, and armament thirteen 0.5in guns. Span is 141ft 3in, length 99ft. Convair B-36H. The "H" is the latest variant of the basic B-36 design in service and is powered with six Pratt and Whitney R-4360-53 engines and four General Electric J47 turbojets. The B-36H is a development of the "D", dealt with at some length in the preceding review (April 4th, 1952). Top speed is probably about 435 m.p.h. and service ceiling over 45,000ft. The latest sub-type is the B-36J, in the production of which a very great saving in man-hours has been effected. Convair XB-S8. The Hustler, as this machine is known, is likely to be the first supersonic bomber, and is regarded as the probable B-47 replacement. A prototype should fly in 1957. A delta, the Hustler may have "podded" General Electric J79s of about 15,000 lb thrust, and will operate in conjunction with the Douglas C-132 tanker/transport. It is known that the Sperry Gyroscope Company is providing the bombing and navigation system, Bendix Aviation the automatic pilot and control system, Emerson Electric the armament phase of the defensive system, and the Sylvania Corporation the detective phase of the defensive system. The undercarriage will retract into the wing. Boeing B-47E rtfutlling by Boeing "boom" method, from KC-97G tanker.
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