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Aviation History
1957
1957 - 0239.PDF
FLIGHT, 22 February 1957 241 Viscount 802 Higher Capacity and True Operational Flexibility for Shorter Stage-lengths A longer Viscount tor shorter stage-lengths: B.E.A.'s versatile and shapely 802 started in service last Monday. "Flight" photograph THE introduction last Monday of the Viscount 802 intoregular service with British European Airways brings ful-filment to the Corporation's plans—conceived over four years ago and announced in February 1953—for a "stretched"version of the Viscount 701. At that time the 700-series air- craft were still .ome weeks away from airline service, and it isinteresting to recall the factors from which stemmed the decision to proceed with a greater-capacity Viscount. In the best-regulated families airframe and engine developmentgo hand in hand. Even before B.E.A. had taken delivery of their first Viscount higher powers were offered from Rolls-Royce(Dart RDa.5s in place of Dart RDa.3s) for a larger aircraft. The new 801 Viscount was intended to fly on B.E.A.'s high-densityroutes to Belfast, Edinburgh, Glasgow, Paris, Amsterdam, Brussels, Dusseldorf, Zurich, Geneva, Nice and Milan; emphasiswas on the short hauls. And although in the gestation period the design departed considerably from the first tentative pro-posals (which envisaged a fuselage stretch of 160in), the need remained for a version with more seats and more capacity to beused on shorter stages, such as those flown at that time by B.E.A.'s piston-engined Ambassador fleet. Nor are the require-ments of a complementary aircraft developed to operate on shorter stage-lengths peculiar to B.E.A.; many other of Vickers'customers could expect to benefit from additional capacity in an airframe with which they were already familiar. The Viscount 802,which was first described in Flight for October 22, 1954, is 46in longer overall and lllin longer in the cabin, and, in comparisonwith B.E.A.'s Viscount 701s, there are three additional rows of seats, a total of 57. For freight transport the shorter-stage lengthaircraft also has folding seats, a strengthened floor and a wide rectangular loading door. Typical of the application of the system of paired Viscounts toother airlines is the case of Aer I.ingus, who have ordered three Viscounts 808s to complement their four 707s. The 808swill be equipped with 65 seats for high-density operations between Dublin and London and the 707s could be released fordevelopment of the Irish line's longer stages from, say, Dublin to Amsterdam. On the other hand, so popular has the Viscount proved, thatit has been found entirely possible to operate the 700 profitably over quite short stage-lengths, as Capital Airlines are doingbetween (for example) Pittsburgh and Detroit and New York to Buffalo. Nevertheless the 700 and 80C are different aircraftdesigned- to operate over distinctly different sectors, a factor which has been emphasized by some shuffling of orders—operators with 700s adding 800s to their fleet and other operators who originally chose 800s reverting to orders for 700s for thelonger of their medium hauls. Before the Viscount 800 reached fruition, Rolls-Royce hadagain increased the power of the Dart, so that—like the later 700-series aircraft—the 802 is powered by RDa.6 Mk 510s withRotol "parallel-plan-form" propellers. The gain in take-off power over the 701—to 1,780 e.h.p. from each engine—is 13per cent. It is unfortunate that the term "flexibility" has deterioratedinto the jargon of brochuremanship, because true operational flexibility is a feature which this latest Viscount to enter servicedisplays to an admirable and much greater degree than have any of its predecessors. When the Corporation's Viscount 802passenger service began on February 18 an all-freight 802 service from Milan to London had already started and the pattern ofB.E.A. operations with their new equipment—which caters for easy conversion of the all-first-class interior of an outward-bound service to the mundane utility of an air freighter for the overnight return-—was taking shape. The additional 46in length of the capacious Viscount 800has been obtained by splicing a section into the parallel portion of the fuselage and moving the pressure bulkhead 65in furtheraft; in this way a centre-of-gravity shift was avoided. Redesigned doors and door sills and a strengthened all-metal floor stressedfor freight loadings up to 150 lb/sq ft involved Vickers in fairly major fuselage modifications; and, as production was in any casebeing extended, it was decided to retool all the fuselage frames. This enabled a clean design of the floor attachment and pressurebulkhead pick-up frames to be made and avoided the repetition of reinforcement modifications during production. Other toolingchanges were then made to the fuselage assembly jigs; the 800 is built up on an internal tool with unrestricted access to theexterior skin panels, whereas the 700s were built in a cradle- type fixture. A1J the interior fittings pick up on the flush seat-rails, theseats fold up against the cabin wall when required and the bulk- heads are movable, so that layout changes to mixed-class seat-ing or a passenger/freighter combination can be quickly made. The folding Short and Harland seat design was chosen byB.E.A. after specifications had been submitted to no fewer than 30 firms—a reflection of the very strong competition which existsin this field. Development of the prototype seats has reduced the weight of die units—which are stressed to the A.R.B. "fore or aftfacing" 9g requirement—by 340 lb (the weight of two pas- sengers) for the complete aircraft. The seats are folded byraising the central arm-rest, removing the inboard leg from the seat-rail, folding it inwards to unlock the outer leg, and stowingthe assembly against the fuselage wall. A small but well-con- sidered feature of the installation is the moulded plastic inter-seat section which keeps the seat-rails clear of debris when the seat units are in the down position. An innovation immediately apparent on external inspectionof the Viscount 800s is that the freight and passenger doors are now of rectangular rather than elliptical shape, although stress-raising corners are avoided by the large radius on the doors and sills. The 4ft-wide, 5ft-high freight door has been designedto accommodate the arms of a fork-lift truck. Pressurized doors present notoriously difficult design prob-lems. The customary bolt-type lock becomes unpleasantly stiff to operate if any residual pressure remains in the cabin on land-ing; as little as 0.1 lb/sq in differential pressure can make the door practically unopenable. Icing, rigidity and door-open windloads are further cases for the designer's careful consideration, because few things leave the passenger with a less favourableimpression than a passenger door that requires a struggle to close
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