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Aviation History
1951
1951 - 0315.PDF
FLIGHT, 15 February 1951 201 planned and executed with care, and would start ideally as muchas 200 miles from destination, although faster descents may be desirable for traffic-control reasons. On a pure jet aircraft,brake flaps are necessary to shorten this descent sector, but with turboprops the same result can be achieved by reducing air-screw pitch so as to get some windmilling drag from the blades. For both types departure from the ideal prolonged descent to themore rapid descent produces rather small changes in fuel con- sumption, and some flexibility is therefore available for traffic-control purposes. It is characteristic of both types that even on short flights the best economy technique is to climb as high aspossible in the distance available. It is possible to see some of the arrangements that are neces-sary to control operations. Since altitude is a critical factor, it must be interfered with as little as possible. Quadrantal rules,as at present used, therefore have serious deficiencies, and it may well be that, for altitudes over 20,000ft, where traffic den-sities for some time to come will be fairly low, the lateral method of separation will have to be adopted. <* Below 20,000ft, particularly with pure-jet aircraft, operationbecomes very uneconomical in fuel consumption. The captains of such aircraft, therefore, need to be given warning of landingdelays before they descend from their economical cruising height. They will then be able to carry out their primary de-laying tactics at the most suitable height. The problem is less serious for turboprops, and we have found a two-engined holdingprocedure at low altitudes very satisfactory as an occasional pro- cedure to deal with difficult situations. In addition to these primary delaying techniques it will benecessary to have a method of secondary holding to absorb errors in the timing of primary delays and to phase the jet air-craft in with the piston aircraft, since we can look forward to mixed operation for some time to come. It is important toselect these secondary holding points and the approach paths from them to the airport so as to give unobstructed approachesto the jet aircraft. Our experience with the Viscount has shown us that we can mix in with piston-engined aircraft in delayingprocedures, but we can foresee certain advantages in being assigned a separate stacking point and our own track into theairfield. With the pure jet this special arrangement for hand- ling becomes vital, and all terminal traffic control will probablyhave to be handled in this way. Diversion from intended destination is another matter callingfor anticipation on the part of the control authorities. Purs jets must be diverted whilst still at high altitude; turboproptypes benefit from this treatment, but are better able to deal with diversion after descent to the intended destination. The arrangements that I have sketched for you very brieflyobviously call for an operational control which is vastly in advance of current arrangements in its scope and efficiency.It will require adequate fixed and air-to-ground communication for rapid exercise of its control functions. This recalls verystrongly my experience as Commander-in-Chief, Fighter Com- mand, where the functions of the controller likewise demandedpositive control over aircraft movements, and I visualize that the civil control in the future will inherit many of the charac-teristics that we have become accustomed to in dealing w.th fighter operations. For instance, a great extension of the pre-sent local radar-surveillance seems likely to form an essential component in monitoring the approach of aircraft to controlzones, and it is quite clear that positive control will be required in future at all levels at which regular services are flying.Controlled air space at higher altitudes will obviously be neces- sary to cater for the increasing number of high-flying aircraft,and these regions will have to be defined without reference to national boundaries, and providedwith adequate flight informa-tion services. You will notice how piston-engine, turboprop and pure-jetaircraft tend to arrange themselves in that order of difficulty when it comes to matters of operational control or operating economics.It is our assessment in B.E.A. that we are now ready to take the step from piston-engine to turboprop operation, and that wecan start our operations without the likelihood of encountering major difficulties. So far as a short-haul airline such as B.E.A.is concerned, the difficulty of taking the next step to pure jets does not warrant the relatively small added attractions offered.It appears to us that, for the compaartively short ranges in which we are interested, the pure-jet transport can reapsmall advantage from its speed. Speed is not a particularly saleable commodity unless it results in appreciable reductions inblock time, and no one is particularly interested in flying at 600 miles an hour if this saves him only ten minutes, when this tenminutes can easily be lost several times over by, for instance, traffic congestion on the way from the airport to the city centre.This very elementary reasoning leads one to regard pure-jet aircraft as unattractive at ranges less than 800 miles. At theother end of the scale, the present high fuel-consumption of jet engines makes ranges over 2,000 miles a severe technicalproblem, particularly for medium-sized aircraft. In our view ;therefore, in present circumstances, the field of application of the pure jet lies in the realm of large aircraft operating betweenranges of 800 and 2,000 miles. . . . For the time being at any rate, we in the B.E.A. pin our faith to the turboprop as the rightcompromise for our particular problem. A PIONEER PASSES WITH the death of Sydney Temple Swaby, B.A., whichoccurred recently at Rotherham, Yorks, another link with the pioneer age of aviation is severed. Born in 1875 and educated at Rugby and Oxford, Mr. Swabywas a civil engineer who, in 1909, became interested in aero- nautics. In that year he went into partnership with R. C.Fenwick in the design and construction of the Mersey mono- plane, which eventually made its first flight from the sands atFreshfield, Liverpool, late in 1911. The Mersey was once referred to as "the first all-Britishmilitary monoplane." Though the claim might in a sense have been made for Bristol, Handley Page and Blackburn monoplanesof the same era, it is certainly true that the Mersey was designed from the outset with military duties in mind—in fact, as afighter. It was of unorthodox design—even for those days— in that it was a pusher with the engine (a 45 h.p. Isaacsonseven-cylinder radial) driving the propeller by a shaft passing through the tandem two-seater nacelle. This arrangement wasadopted with the express purpose of enabling a forward- firing gun to be mounted.Mr. Swaby's son, F/L. W. P. Swaby, will forgive us if wequote a passage from Flight of August 17th, 1912, for it is socompletely typical of the rough- and-ready structural-researchmethods of those days. Flight's representative having ques-tioned the strength of the Mer- sey's tail bracing, ". . . Mr. Fen-wick told us that he had tested the strength of that section byhanging a man from' the ex- treme end of the tail and liftinghim clear of the ground by the manipulation of the elevator inthe slip stream from the pro- Dellor. It had withstood thattest perfectly. . . . The monoplanewas entered for the 1912 Military Trials on Salisbury Plain but crashed on its thirdcompetition flight; Fenwick, who was piloting it, lost his life. Apart from his aircraft-construction work, Mr.Swaby was on the engineering staff of the Isaacson Aero Engine Co., of Leeds, until the outbreak ofthe 1914-18 war. He assisted in the design of their power units, which, surprisingly at that earlyperiod, included a large double-bank radial. aph of the Mersey monoplane, taken Trials on Salisbury Plain in 1912. Mr. S. T. Swaby.
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