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Aviation History
1956
1956 - 0162.PDF
7000 4000 1*000 |4POO 2pOO VOOO 4>V \\ i 160 V SUBSONIC TO HYPER SONIC . . 0-5 10 15 CRUISING MACH 20 2-5 30 Fig. 6. Maximum cruis- ing range for different species of aircraft at their design Mach num- bers: A is airscrew driven, B is turbojet-powered and C is ramjet-powered. turbojet efficiencies continued to increase up to Mach numbersof at least 2. If high-efficiency multi-shock intakes and con- vergent-divergent nozzles were used this improvement could bemaintained up to a Mach number of nearly 3 with the turbojet and to at least 4 with the ramjet.Ranges calculated from the above assumptions could be plotted against design Mach number (Fig. 6). It was obvious from thiscurve that really long ranges were quite out of the question at transonic speeds, whereas increase in Mach number brought aprogressive recovery in range up to the highest speed at which the aircraft could fly in the face of aerodynamic heating. Evengreater ranges were possible at hypersonic speeds if the problems of aerodynamic heating were reduced by flying in the outer reachesof the atmosphere. This, however, introduced completely dif- ferent problems. Meanwhile, ranges at lower speeds could beimproved by various detail refinements; if the expense were justi- fied even greater improvements were possible with new fuels, bothchemical and nuclear. Long-range supersonic flight would require extreme concentra-tion on one design Mach number, since over 90 per cent of the flight would be carried out at this Mach number. In contrast,the present supersonic fighter might fly 90 per cent of its time at subsonic and transonic speeds, requiring considerable com-promise over a range of Mach numbers. The design of supersonic aircraft involved balancing importantfactors which interacted very considerably. As a result, the primary designers had to have a better appreciation of the overallproblems than had been possible under present organizations, where the powerplant and equipment had been designed separ-ately to equip a number of different specifications. Even if some FLIGHT items found applications in aircraft with less performance thedesign would initially have to be baited on the aircraft with the greatest performance. This process of integrated design hadalways existed for guided weapons. In the aircraft industry the main problem was one of personnel reorganization and training. Turning to the more technical problems of stability and control,said the lecturer, the importance of characteristics at lower speeds could not be overlooked, since the aircraft would have to flythrough the complete range of Mach numbers at each end of every flight. An ideal design for high supersonic speeds was unlikelyto have very good take-off and landing characteristics, and would not necessarily be satisfactory at transonic speeds. This mightmean that a considerable part of the initial design period would be spent in making these characteristics safe without undue pre-judice to the cruising performance. Stability and control at the design cruising speed had to be perfected to a much greater extent.If the e.g. were kept near to the position required for take-off and landing, most longitudinal instabilities disappeared at high super-sonic speeds. However, unless the e.g. were controlled, the prob- lem was likely to be the inverse one of trim drag owing to anexcess of longitudinal stability. Lateral stability was a more delicate balance of aerodynamicforces and might require more attention over the full range of Mach numbers. The highest attainable speeds would be employedonly at extreme altitude and, as a result, damping and response effects would be abnormal about all axes. This exaggerated theimportance of inertia forces compared with aerodynamic control forces; unless the pilot/servo could accustom himself to the newstate of affairs it would be essential to complicate all the controls with autostabilizers or other such devices. This provided another example of the manner in which aircraftand guided-weapon design principles were converging at high supersonic Mach numbers. Nevertheless, wherever the missionwas really complicated the basic unreliability of a completely automatic system would have to be accepted for some time tocome. Flexibility of the human element seemed essential for monitoring individual functions (reducing complexity), and totake over or discriminate between functions when elements failed. The degree of safety required for civil aviation was such thata human crew seemed essential to supplement automatic control as far as the future could be foreseen. This also seemed true ofmilitary aircraft where it was essential to return reconnaissance, or other, equipment to its base. Other operations might see a longtransition phase where automatics slowly replaced the human functions. The remainder of Mr. Creasey's wide-ranging paper dealt withhypersonics, thermal heating, superaerodynamics, and the bal- listics of rocket flight. This part of the paper will be abstractedin an early issue. REMEMBERING THE 504 ONE of the most intimate—indeed, exclusive—-events in theaeronautical calendar is the reunion dinner of the Avro 504 Club, convened this year at Londonderry House on January 27th.On this occasion the Avro prize apprentice of the year is inducted into the fraternity and, together with his immediate predecessors,sits at table with the great "A.V." himself. Of the select com- pany also are men who worked, themselves as apprentices, on oneof the greatest aeroplanes of all time; and principal guests this year were Lord Brahazon and Avro's energetic young general manager,J. A. R. Kay. There was a warm welcome, too, for Frank Buckell, manager of General Electric's aeronautical departmentand a founder-member of the Sopwith Aviation Apprentices, after the example of which the 504 Club was formed. The presi-dency of Sir Roy Dobson ensured that the evening went with a swing. As always, the menu card was a joy—a Wren master-piece alive with sketches acknowledged to J. M. Bruce's history of the 504 printed in Flight during 1934. The organizing of each successive dinner is in the hands ofShell's Joe Taylor and Avro's Philip Kidson, and it was the former who expressed everyone's pleasure at seeing Sir Alliottlooking younger than ever. Proposing "The Company," A. Cdre. G. F. Smylie recalled some of his impressions of Avro types,ranging from No. 939, a 50-Gnome Avro requisitioned by the Admiralty in 1914, to the Vulture-engined Manchester.Responding, Sir Roy Dobson had something to say about how Avro were keeping "ahead of the game." No other company inthe industry, he said, could hold a candle to them in the matter of scientific equipment, which he instanced by the two existinghigh-speed tunnels and a third, designed to operate at Mach 3.5, now in prospect. The elaborate test equipment of today heexemplified by the rig for testing Vulcan controls, which had completed 1,500 hr at full load. Proposing "The Guests," Mr. H. E. Broadsmith said that whenhe had written "Type 504" at the bottom of his drawings so long ago he little thought the number would become so famous. Responding, Lord Brabazon spoke in the warmest terms ofSir Alliott's introduction of the classical tractor biplane formula which had dominated aviation for a long period. This type ofmachine he distinguished from such craft as the Howard Wright, flown by his boyhood friend Tommy Sopwith, and which hedescribed as a slavish copy of the Farman. On this machine, nevertheless, Sir Thomas had made his remarkable flight toBelgium, as a reward for which "he trousered 4,000 Jimmy O'Goblins." Lord Brabazon spoke also of his other friends in theHawker Siddeley Group, referring especially to "Dobbie" as a dispeller of gloom and one who had four units of personalitywhere the rest of us had one. Widi a twinkle in his eye Lord Brabazon went on to consignV. 1000s, DC-8s and Boeing 707s to perdition, deploring that flying had now become aerial transport, devoid of excitementexcept for the prospect of being burned at the end. On a recent flight he had found a fat lady on each side of him and could notget at his cigarette case. Such travel he described as an insult to one's individuality, and in his opinion the Siamese were betteroff. Flying in his youth he described as "feeling like sitting on a blancmange in a strong draught." He recalled that he had wonthe Michelin Trophy at an average speed of 38 m.pJi., and he doubted if anyone could equal this feat today, so little attentionhaving been paid to the lower end of the speed range. Presenting the Avro 504 Club Trophy to Alan Lawson, thefourth apprentice to receive the reward, Sir Alliott Verdon Roe recalled that he himself had been to Canada when he was 14. Hewould like to see the company turn out what he described as a "super passenger machine." (Remark from the chair: "Sowould I.") Thereafter several of the company were called to their feet,among them Mr. Kay, who warned the newer members against red tape and bureaucracy. If they could not cut through the redtape, he counselled, they should at any rate not allow themselves to be stifled by it. ••rsr
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