FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1960
1960 - 3108.PDF
1024 FLIGHT, 30 December 1960 SUPERSONIC - TRANSPORT IMPLICATIONS More About the RAeS Symposium AN initial report was published in last week's issue on the RoyalAeronautical Society's symposium on supersonic transport aircraft, held in the new RAeS lecture theatre on December 8. This further accountcovers the remaining papers delivered and the subsequent discussions. PODS, or buried engines? This hoary old question, whichwas so hotly debated when contemporary jet airliners werelines on a drawing-board, cropped up in a new context at the Royal Aeronautical Society's symposium on supersonictransport aircraft. The chief technician of the Hawker Siddeley advanced projectsgroup, Mr P. L. Sutcliffe, put forward a strong case for podded engines on supersonic airliners when he addressed the 400engineers, pilots and planners attending. He said that podded engines can now be far more closely cowled, with the groupingof accessories in the pylon, than was once thought possible. Thus low frontal areas could be achieved and very similar wave dragcould be obtained for the podded engine and the two dimensional, semi-buried installation. There was little to choose in weightbetween the two types of installation. It was in removing and dispersing the boundary layer that thepodded engine offered its advantages. A semi-buried installation would probably have a considerable boundary layer ahead of itsintake ram, whereas with the podded engine there would be a boundary layer present only on the intake centre-body. "Lots ofeffort must be placed on the podded engine," said Mr Sutcliffe. "It's a runner now, though it did not at one time appear to be." The question has never failed to provoke controversy and itdid not fail to do so at this symposium. Dr Seddon, of the RAE, took issue with Mr Sutcliffe, saying: "Our future lies in moresophisticated integration of shapes. Burying the engines is only the first stage in solving the integration problem." Dr Seddoncalled for more positive thinking on treating the boundary layer. A speaker from the National Gas Turbine Establishment sup-ported the podded engine by saying that the complete powerplant would have to be exhaustively tested in development and a poddedinstallation could be tested with very little extension of existing facilities. He predicted that the development of two or moreengines sharing the same variable intake would be a very difficult task. Mr H. Pearson, of Rolls-Royce (whose paper was reportedlast week) implied support for the buried engine by commenting diat one could not make such a practical and efficient circularintake as a flat one. The rear-mounted engine was very much in vogue and was better because of the noise fatigue problem—though he thought those might be "famous last words." Mr Wolfe, of the RAE, had brought up the question of fatiguebeing caused by high noise levels at take-off and during the climb. Boundary layer noise came into this; during tests at RAE witha Fairey Delta they had found boundary layer noise as high as 140PNdb, a level just capable of inducing fatigue. Another speaker from Hawker Siddeley's advanced projectsgroup, Mr Morris, supported Mr Sutcliffe and left no doubt in his listeners' minds that Hawker Siddeley's eggs are packed in poddedbaskets. He said that the failure of one variable intake in an integrated installation would affect all the engines: for one failure,there might be a triple failure. The only possible justification of the integrated installation, in his view, was lessened drag. Sonic-boom problem The first gloomy prognostications about sonic booms, the oneproblem which dominated the whole symposium, were aired by Mr Sutcliffe in his paper. Nobody had yet experienced regularsonic bangs, such as would be generated by scheduled supersonic aircraft, and it was difficult to forecast their effects. The weightand altitude of the aircraft were the two factors which determined shock-wave intensity at ground level, measured in lb/sq ft. Itappeared that all but the lightest aircraft flying supersonically above 60,000ft would produce a shock wave at the ground weilin excess of llb/sq ft—and that allowed for a reflectability factor of two, measuring the shock as a human being would experienceit in his ears when standing on level ground. An M2 aircraft flying at 60,000ft would leave behind it a"continuous boom region" about 30 miles wide for all but the first and last 80 miles of its flight. This would be a serious publicnuisance; but the speaker displayed a "press on" spirit, feeling that the design of supersonic aircraft should continue while theanswer to the problem and the tolerable levels were sought. Mr Morris was very pessimistic on this question. He thoughtthat any supersonic transport of more than 200,0001b was going no "generate shock-waves of objectionable intensity. Millions ofpeople would be aSected, saVj'by a coast-to-coasA. supetsonic ftvght across the USA. He thought that both the British and United States Governments would prohibit supersonic airline flying overpopulated areas. "If we prohibit it, can we expect Egypt, Iraq and all the others not to do likewise?" he asked. He then turnedto the economic effects of such a prohibition. A 35 per cent increase in direct operating costs would result on the London - LosAngeles route from the need to fly subsonically over parts of the routes. Fifty per cent would be added to costs between Londonand Johannesburg, 40 per cent between London and Sydney and 70 per cent between London and Tokyo. One of the three airline speakers, Mr C. H. Jackson, BOAC'sassistant chief engineer, displayed the airline man's proper caution in not wanting the supersonic transport to be developed until thenature of the shock-wave problem was known and its solution found. His talk on operations and economics was tinged withwitty cynicism. "Operators have been told that supersonics are a new and fasterway of going places," he began. "We are told that their effects on human affairs 'are not exactly known, but are bound to be bene-ficial. The technical challenge should be exciting and we must remember it involves national prestige. Let's find the funds andget on with the job.' "The same kind of argument probably motivated Columbus,"Mr Jackson said. The challenge of the supersonic transport was an economic one and designers must not forget this. Unlike anyother industry, the airline industry's product had grown pro- gressively cheaper. Every major advance had resulted in lowerseat/mile costs and therefore lower fares. "This economic progress is seen in current economy-class fares. These are down 30 percent when all retail costs have increased." For this reason, air- lines eyed supersonic transports with suspicion. The top tenper cent of total traffic (Top People?) would be insufficient to support large-scale supersonic airliner production, so costs mustnot be substantially increased. If subsonic costs could be con- siderably decreased from present levels, the supersonic transportmight then bear the differentials. Supersonics and ATC The economic advantages claimed for M2 or M3 transportsmight disappear if kinetic heating demanded special and expen- sive fuels or additives, Mr Jackson considered. With regard togaining the best utilization, he did not think that equipment pool- ing between airlines would help much: "There is a limit to howmuch one can lower the frequency of service, or restrict the pas- senger's choice of carrier, in return for shorter journey times."He was worried about the air traffic problem. Would a system failure causing a delay of lOmin lose the aircraft its departure"slot" in a highly geared ATC system? (Capt Kane, of BOAC, later commented that he saw "no hope whatsoever" that ATCauthorities would accept supersonic aircraft by 1970.) Then the meeting was brought back to sonic booms again.If booms, or rather the avoidance of them, dictated subsonic over-land flying or lengthy coastal diversions, particularly aroundIndia, the Polar route to Australia could be used, flying south over the Pacific. This would increase the route distance and losevaluable sector business. "Sector business is a valuable part of BOAC's whole business," Mr Jackson said. "We haven't theoperational answers; we haven't the information to provide the answers. In this we are no worse off than any other operators—we all have to wait a year or so for more information from aircraft designers," he concluded. The first questioner foresaw that the avoidance of booms overpopulated areas could lead to an unbalanced transport system by 1970. In terms of elapsed time, New York might be nearer thanRome and Australia nearer than Cairo. It was a safe bet that with members of Handley Page's engineer-ing staff in the theatre, the audience would hear of the benefits of boundary layer control. Mr C. Lee was quickly on his feet toindicate that the company had studied BLC for both subsonic and supersonic applications. Mr Jackson might have underestimatedthe competition which supersonic aircraft would have to face from cheaper subsonic types. BLC could bring down subsonicoperating costs to only 6d/ton-mile from ls/ton-mile. The best hoped for from a "conventional" M2 aeroplane was 15d/ton-mile. "What is the answer?" asked Mr Lee. "Why, a more efficientM2 aircraft, one with BLC!" Supersonic operating costs would then drop to perhaps, lld/ton-mile. A more exotic solution,of course, was variable geometry. "A slewed wing sounds nice," he said. "It gives the sense of intoxication appropriate to thiskind of thing." British European Airways were represented at the symposium bv their flight technical superintendent, Capt F. OrnvonroYd, who thought that operating techniques of supersonic aircraft might
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
