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Aviation History
1960
1960 - 0604.PDF
604 Ramjetti Milanese IMPRESSIONS OF THE AGARD COLLOQUIUM ON HIGH MACH NUMBER AIR-BREATHING ENGINES BETWEEN April 4 and 8 the Combustion and PropulsionPanel of AGARD sponsored a colloquium in Milan underthe general title of High Mach Number Air-Breathing Engines, with the active and generous help of the Politecnicodi Milano as hosts. The meeting-place—the Leonardo da Vinci Museum—was a happy choice, for in studying the drawings andmodels of the great master's manifold incursions into scientific and technological fields, whose fruition lay (for him) far in thefuture, one was constantly reminded of the limitations of lesser beings, and came suitably humbled to the many and variousfountains of more recent knowledge. No AGARD function could fitly begin without a contributionfrom Dr Theodore von Karman, who obliged characteristically by excusing his "conservatism" in being enthusiastic about the"relatively unfashionable subject" of air-breathing engines by reminding us thai he had qualified as a "reactionary" by advocatingthe missile and rocket aspects of spaceflight at a time when "many of the extremists advancing on our solar system were still in theirscientific infancy." He thought there might still be a time, some- fifteen years hence, when some people would settle for a leisurelytwo-hour trip from Los Angeles to Paris to enjoy an ample con- tinental meal and acclimatize themselves properly to the Europeanpace. In the latter connection, it was noticeable that not only the American speakers had red lights flashed at them by the veryable instantaneous translation team (Inglese, Francese and Italiano, but not Tedesco) when the pace got a little too hot! The first session concentrated on The Future of Air-BreathingEngines, centred on papers by A. Ferri (Brooklyn Polytechnic) on Possible Directions of Future Research, and by M. A. Zipkinand L. Nucci (General Electric, Cincinnati) on Composite Launchers. These outlined possible uses for the air-breatherfor a cruise-type long-distance vehicle and for the launching of satellites and space vehicles, and gave performance data bothon the vehicles and on ramjet powerplants for them. In connection with the launching of satellites, General M. Hooks of the USAFAir Research and Development Command made the significant observation that 60 per cent of the fuel required is used at speedsbelow Mach 6, which for the purposes of this meeting was well within the operating regime of air-breathers. In view of constantlyreiterated pleas for more funds (preferably American?) to develop such engines, Dr A. M. Rothrock (National Aeronautics andSpace Administration) came near to bringing his audience to tears when he spoke of the "agonizing reappraisal" which NASA hadhad to make before deciding to spend the bulk of its annual thousand-million-dollar budget on rocketry rather than air-breathers. In his opinion, a hypersonic ramjet project would cost a hundred million dollars a year, in engineering rather thanpurely scientific effort. The second day brought contributions from J. A. Drake (USA)on Hypersonic Ramjet Development and from G. L. Dugger (Johns Hopkins University) on Engines with Supersonic andSubsonic Combustion, followed in the afternoon by papers by J. F. Connors and L. J. Obery (NASA, Lewis) on Considerationsof Hypersonic Inlets, a mainly theoretical survey which was supplemented by a particularly able presention of experimentaland analytical work by G. H. McLafferty (United Aircraft Cor- poration research laboratories) under the title Hypersonic InletStudies. Points at issue here were the search for the optimum inlet configuration, cooling requirements, and the difficulty ofadequately predicting inlet losses, particularly where the geometry is variable. In the discussion, Dr J. Seddon (RAE Bedford) helpedto keep our feet on the ground by pointing out that it was all very well to speak of placing intakes and exhaust nozzle in favourableregions of the pressure distribution round the vehicle but that, at speeds around Mach 4, the engine was likely to be by far thelargest part of the vehicle. He also pointed out that, at these speeds, pressure recovery alone was a deceptive criterion of intake"sophistication," and that at sufficiently high speeds quite simple configurations came back into the picture on grounds of increasingkinetic-energy efficiency. Wednesday was concerned with Supersonic Combustion andDetonation, with papers by H. Behrens and F. Roessler (Institut Franco-Allemand de Reserches de St Louis) on Supersonic Dif-fusion Flames, and a formidable analysis of Plane Detonation Waves by A. K. Oppenheim and R. A. Stern (University of FLIGHT, 29 April i660 ,.., California, Berkeley) which will surely become a stand? ireference. Thursday's session provided a fascinating contrast, with pap sin the morning by P. P. Wegener (Jet Propulsion Laboratory • Cal Tech) on Supersonic Nozzle Flow with a Reacting ,_, 5Mixture, and by E. A. Lezberg and R. B. Lancashire (NAS Lewis) on Expansion of Hydrogen-Air Combustion Products, a dafter lunch a British contribution by J. H. Horlock (Liverpr ,] University) on Research in Turbomachinery. On the first topithe complexity of the experimental and analytical procedu s needed to distinguish between equilibrium and frozen flows, ev. nwith very simple chemical systems, was vividly brought out (wLn price "freezing" at 3,000 degrees Rankine?). However, in con-tributing to the discussion of an earlier paper, D. H. Mallinsn (National Gas Turbine Establishment, Pyestock) had pointed cutthat some 60 per cent of the dissociation energy of exhaust pro- ducts was due to carbon monoxide, which gave hope of a simpierapproach without too much loss of accuracy. On the subject if turbomachinery, it was refreshing to find interest centred on triehomely Mach number range (under Mach 3) below that at which other speakers had started: here one ungratefully wished for abridging of the gap by the inclusion of a paper on hybrid power- plants such as turbo- and ram-rockets. The final session was concerned with the search for materialsable to withstand the extravagant demands of some of the earlier proposals, a burden shouldered jointly by P. Duwez (USA) onMaterials Limitation, and by A. J. Kennedy and A. J. Murphy (College of Aeronautics, Cranfield) on Temperature Effects onMaterial Characteristics. Though both papers reviewed a wide range of materials, familiar and otiierwise, with considerableemphasis on graphite, the second cast its net wider in considering the possibilities of cermets. From this welter of specialized contributions it is hard for amere observer to present a concise overall conclusion. That there is life in the old dog (the air-breather rather than the observer,about whom grave doubts remain) yet was evident, but so also was the need for elaborate veterinary treatment to make said dog'slife worth living. Particularly would it be difficult for the poor hound to avoid grievous injuries as he advanced further into thefamous "thermal thicket" (an expression produced by one speaker with a touching air of having evolved a new turn of phrase), andbesides tanning his hide with rare and costly materials he might, like Samson's lion, need to be turned inside out to cool hisinnards by radiation. Taking his liquid nourishment at unpre- cedented speed would present his digestive system with new prob-lems and, while simple means of swallowing might yet prove adequate, the converse process would need more careful thoughtand painful experiment. So ended a conference in which a field of heroic proportionswas surveyed, and one looks forward to early publication of the proceedings to facilitate a fuller appreciation of the picture in theround, wherein the occasional shortages of preprints, and diffi- culties of absorbing detailed comments in instantaneous transla-tion, are rectified. One could have wished for a more even distri- bution of papers between the various nationalities represented,although the prepared comments showed that the preponderance of American authorship of papers did not by any means reflecta one-way traffic of ideas or of experimental interest. That this interest was not more fully supported by unscripted commentswas perhaps inevitable with so much to be said in so little time. Still, there were those among the delegates who found a partingencouragement from Leonardo in his proposal for a man-powered aircraft: it may not be hypersonic, but it might yet win himthat £5,000 prize by proxy. J. R. PALMER April May May May May May May May May May May May May May May 30 8. 2. 3-13. 4. 4. 5. 6. 6-8 9-11 11. 11. 11. 12. 19. FORTHCOMING EVENTS Rally and Second-hand Aircraft Sale, Cosnes, France. Society of Engineers: "Problems of the Launching of Black Knight," by G. E. Tharratt. Mechanical Handling Exhibition, Earls Court, London. British Institution of Radio Engineers (Computer Group): "Computer-controlled Television Displays for Flight Simulators," by J. N. Naish. Kronfeld Club: "Army Aviation, Past and Present," by Maj P. A. Downward. RAeS: Annual General Meeting. RAeS Rotorcraft Section: "The Personal Helicopter," by J. S. Shapiro. Shackleton Sales Weekend, Kidlington, Oxon. Institute of Welding: Spring Meeting. RAeS: Second Halford Memorial Lecture (at Hatfield), "Powerplants for Supersonic Transports," by J. S. Alford. British Institution of Radio Engineers (Radar Group): "Radio Guidance in the Automatic Landing of Aircraft," by J. Shayler. Kronfeld Club: "Around the USA," second of two lectures by John Furlong. RAeS Astronautics and Guided Flight Section: "On Reducing Costs of Space Research," by J. E. Allen. RAeS: 48th Wilbur Wright Memorial Lecture, "Mathe- matics and Aeronautics," by Prof M. J. Lighthill.
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