FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1954
1954 - 1576.PDF
FLIGHT, 28 May 1954 697 Stratotanker Boeing's New Prototype, Called Stratoliner in Civil Form THE Boeing Airplane Co. of Seattle is one of the largest aircraft firms in the world. They occupy plants at Seattle and Renton (Washington State) and at Wichita (Kansas) with an aggregate em ployment of at least 80,000. Such a com pany has a potential to be reckoned with under any circumstances and its achieve ments since 1945 have, in fact, been immense, if largely of a military nature. During the late 1940s Boeing saw clearly that a jet transport was going to be needed, both for military and civil applications. There was at this time a considerable body of opinion in America which felt that we in Britain had been able to develop a jet transport solely by the expenditure of Government money and that the operation of such aircraft was possible only when the airline was underwritten by the taxpayer. The argument generally concluded that the American industry had to be cautious, owing to its dependence on stockholders, and that jet transports were, as a consequence, not for the immediate future. Boeing did not fully subscribe to this view. On the other hand, they were very careful to ensure that, when they produced their new transport, it would have the optimum layout. Trans port design is, as we outlined last week, a tricky business, in which there is no room at all for anything less than the best. Boeing are old hands at the airline game, for their Model 247D was the first modern monoplane airliner and the Stratocruiser needs no introduction. Nevertheless, the company were shrewd enough to aim at producing an aircraft, the basic design of which would be suitable for the widest possible range of roles. Most of the engineering information acquired by Boeing stemmed from the B-47 and B-52 bombers, the KC-97 tanker and the civil Stratocruiser, but much additional information was obtained from over 150 "paper" projects which never flew— turbojet and turboprop aircraft of all shapes and sizes. Some of these projects were no more than rudimentary layouts and weight statements, but a score of others were carried far along the process of design and stressing, including extensive tunnel testing and exhaustive mathematical analysis, the final results being worked into brochures for consideration by military and civil customers. The work really began in 1946 when the design staff were largely occupied with the B-47. The commercial jet project was known as the Boeing 473 and the first proposal was quite a small aircraft powered by two Rolls-Royce Nenes. At the end of 1948 the design department had reached the twenty-fifth project which was a 264,000 lb aircraft powered by six of the new Pratt and Whitney J57 turbojets. Other variants were conceived as turboprop aircraft for feederline use. But by mid 1949 it was apparent that neither Boeing nor the potential opera tors had sufficient knowledge of jet transports to justify detailed design. Accordingly a comprehensive study of jet transport operation was undertaken based on the performance of a hypothetical aircraft. This, said Boeing, constituted by far the most thoroughly filled package of jet transport information assessed by anyone at that time." The study evoked favourable reaction and prompted further design along somewhat different channels. A significant point was reached in 1950 with the Model 473-60, a design which was projected in two 60-passenger versions, a 135,000 lb domestic model and a transocean aircraft shown in weights up to 180,000 lb. But extensive tunnel testing and engineering study gave rise to doubts which centred largely about the undercarriage—a narrow-track tricycle arrangement with all three units housed in the fuselage. So much for the early airline projects. While progressing with the 473-60 Boeing was also searching for the best form for a new tanker-transport for the U.S. Air Force. By 1950 it was already apparent that the KC-97 Strato-freighter, capable as it is, could do no more than a marginal \ At Taken from the roof of the Renton factory during the "roll-out" on May 14th, this photograph shows the movable wing-surfaces discussed in the text. The flaps are discon tinued behind the inner engines, the space being occupied by the small flipper ailerons; the four spoilers are also clearly visible. The large trailing-edge fillets are necessitated by the housing for the retracted bogies. refuelling job for the U.S.A.F. bomber wings then being formed. What was wanted was an aircraft which could refuel the B-47 at the latter's own height and speed. It appeared that it might be possible to retain the "97's" capacious fuselage, restricting alterations to the wing and power plant group. On this basis, therefore, a spate of Model 367 tanker/transport designs began to materialize. One of the earliest merely replaced the Stratofreighter's piston engines with four J35 turbojets. By 1950 the Model 367-31 was developed with four Wasp Major piston engines and two J34 turbojets; another of that year was the gull-winged Model 367-60 with four T34 turboprops. But there was a grow ing feeling that, as American combat air power was steadily becoming all-jet, the optimum tanker would likewise be an all-jet aircraft, with appropriate speed and altitude capabilities. Late in 1950 the 367-64 appeared; this was a C-97 with an entirely new thin wing, two twin jet pods and a new side-folding bogie undercarriage developed for previous new-wing revisions of the C-97. Drawings of the 367-60 and 367-64 were published in our issue of April 16th last. Boeing engineers entered 1951 hard at work upon the 367-64, and the company has pointed out the scale of effort applied; in fact, this project acquired more high-speed tunnel time than many faster aircraft required before the actual flight of a proto type. Six complete wing configurations were examined, cul minating in a 140ft wing of 2,500 sq ft area and 25 degrees leading edge sweep, a low thickness/chord ratio being chosen in order to achieve the desired Mach number. The work on the "64" was most instructive, and, as the market for a jet transport had still not developed in 1951, the company's design teams fell back to assess the overall position. The "64" was a good aircraft and one of the first to have a really sound undercarriage; it had also opened the way to necessary improvements in fuselage form, the original double-bubble giving way to a pure oval cross section. Nevertheless, it had its shortcomings. Most of these stemmed from the thin wing, which not only caused manufacturing difficulties but made it impossible to accommodate the desired internal fuel capacity. During 1951 yet another new wing was laid out with 10 degrees more sweep (to the same 35 degree total as employed in the Boeing bombers) and consequently greater thickness; the area of 2,500 sq ft was maintained and the span reduced to 130ft. It was upon this wing that Boeing finally began to make plans for the construction of a prototype. During the last months of 1951 the lessons learned both from "paper" and real aircraft were sifted and revalued and the amount of heavy-jet and tanker information obtained is still claimed to be unmatched by any other company. In particular, the company realized a most telling and encouraging fact: that the study of the art was then such that the requirements for a civil airliner and a military tanker/transport could be made by a single basic design with penalty to neither r61e. Thus was the way cleared for the financing of further developments, with the possibility of large military production offering an invaluable basis for commercial success. At a meeting of Boeing's board of directors in April 1952 $15m (£5,350,000) of stockholders' money was voted towards the development and construction of a proto-
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
