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Aviation History
1961
1961 - 0132.PDF
132 H2 + O2 ENGINE This simplified cross-section shows the mechanical design of the LR115 pro- pellant injector. As noted below, the streams of liquid oxygen (entering at A) are each surrounded by an annular flow of gaseous hydrogen (entering at B). Some injectors have shown no deterioration after more than 20hr firing and bands on a mandrel. During the brazing operation, theassembly is rotated on its axis to provide uniform brazing alloy coverage. The propellant injector is a concentric jet-type with the centralliquid-oxygen stream at each injection point surrounded by an annular stream of hydrogen gas. The central bulkhead, whichseparates the two propellants in the injector and incorporates the oxygen jets, is machined from a single forging. Another feature of the LR115 design is that the flexible sectionscommonly employed in engine plumbing to allow minor misalign- ment have been eliminated. With reasonable dimensional toler-ances, it has been possible to use rigid plumbing throughout the engine. Because of the low-temperature service and large numberof thermal cycles involved, the use of rubber and plastic seals has been avoided. Metallic seals developed for liquid-hydrogen servicehave proved to be leak-tight after repeated thermal cycles and long-time storage. To provide for multiple restarts in space, a high-energy electricalspark system was chosen for ignition. Most of the components were taken directly from the equipment already developed forthe J57 jet engine. A single exciter system, which is vehicle FLIGHT, 27 January 96l mounted, provides the energy for the spark plug in each ej ^inein the Centaur installation. This insures simultaneous lig ting of the two engines, and tends to reduce the tolerance of kn ulsdifference on a start-up which improves vehicle controllabiL y. At West Palm Beach is the complete LR115 developmen andpropellant-production complex. The engine test stands in .iu four horizontal pads; a vertical stand is used for testing Wengines in combination with the vehicle propellant-supply s1. tem and the component test complex has 20 individual stands. Approxi-mately 2,500hr have been accumulated in component testing in the LR115 engine development was initiated in October ;95gThis work includes testing of individual fuel and oxidizer pumps' the turbine, gears and control components. Over 500hr vvereaccomplished on various bearing configurations alone, yielding a design which has demonstrated better than 25hr of usable bearinglife under simulated turbopump operating conditions. Where po sible, all parts of the engine have been rigorously tested as com-ponents prior to their being committed to complete engine test Pratt & Whitney Aircraft has consumed over 10 million USgallons of liquid hydrogen in engine development testing since 1955. The first complete experimental LR115 was fired in July1959, nine months after the design was initiated. Special equip- ment has been used to simulate space starting and running condi-tions. The engine is mounted on a thrust bed inside an altitude tank which is aspirated by a two-stage steam ejector during thestarting period. As the engine starts, a lightweight door is blown open at the end of the diffuser section. During steady-state run-ning, the diffuser provides the pressure necessary to maintain full-flow conditions in the 40 :1 exhaust nozzle. Since the startingpropellant flow is sufficient to choke the thrust-chamber throat at the pressure level maintained by the steam ejectors, spaceconditions are accurately simulated over the complete operating cycle. Firing durations of 5.5min, the limit of propellant tankcapacity, have been accomplished on these test stands. In the testing to date on the single-position stands, the LR115engine has met or exceeded all performance requirements. A programme to simulate the Centaur vehicle system is now underway in the vertical test stand, in which the flight-vehicle pro- pellant-supply system is tested with a dual engine installation.At the time of writing, initial cold-flow tests have been completed, and hot firing tests will begin in the near future. CODY'S FIRST FLIGHT A CLOSE study has recently been made by the aeronautical historianMr Charles Gibbs-Smith of the question as to when S. F. Cody made his first successful flight, and the following account summarizes hisconclusions on the subject. I HAVE recently been bringing to a close my researches on the"Cody case," with full documentary evidence that (a) his first tests were in September 1908 (the very first test being an enginetest on September 19); (b) that there were no tests prior to September 19, let alone in May; (c) that one and all consideredthe flight of October 16, 1908, as the first flight, after taxying and take-off tests from September 21 onwards. Before finalizing my report, I chanced to be dawdling throughsome photostats of the early Famborough documents relating to Cody's 1909 tests with the reconstructed machine, which hecontinued to modify successfully through the months; and to the Dunne tests in Scotland the previous year, 1908. In one of Cody'sreports, stamped and dated "HM Balloon Factory, Farnborough. 14 JUL. 1909" occur these words, Cody's own: — "On Monday, 12th July, started the day's experiments with the usualoutriggers, including the triangular tail piece that was on the machine during its first flight in October last." The "tail piece" was the well-known fantail which is to be seenin great detail in all the crash pictures taken on October 16. It had for long been clear that Cody was referring to the October 16 flightin his Aeronautical Society lecture, and elsewhere, but it is gratify- ing to have one more piece of clinching evidence from the manhimself. Then, surprisingly enough, Capper had referred to Cody, ona number of occasions, when giving Dunne news of what was happening down south when the latter was in the wilds of Scotlandin 1908. On September 26, 1908, Capper wrote to Dunne: — "Cody's machine steers very well on the ground but his belts slip,and consequently he cannot get sufficient thrust at present to keep in the air." This would refer to one or more of the ground tests which arerecorded as taking place on September 21, 24 and 28. Then, on September 30, Capper wrote: — "Cody's machine flew about 75 yards down hill yesterday, at no greatpace. Belts slipping badly. He seems quite pleased with it. It steers wonderfully well, while running on the ground." This passage refers to one of the tests made by Cody late the previous afternoon, when The Times correspondent said that the machine was off the ground for 78yd. Finally, Capper wroteto Dunne (in a letter of October 19): — "You will have seen the smash of Cody's machine in the papers.It flew very nicely but he tried to turn too sharply and too close to the ground . . . wing dipped, touched the ground, whole concern turnedround and stood on its head. You must insist on no attempt to turn except very slight serpentines." Capper had said in his official report on the actual day(October 16): — "However, another clump of trees beyond looked so forbidding thathe thought it appropriate to turn to the left and try to come down on a piece of ground. ... He turned, gradually sinking all the time.The left wing tilted down, and struck the ground hard, crumpling up the tips. Then of course, the machine turned round and fell on its nose." This famous flight, the first powered flight in Britain, was alsodescribed in detail both by Cody himself and by the eyewitness correspondent of The Times. When Cody had struggled out ofthe wreckage, he told the onlookers: — "I am sorry that the accident occurred, but I have accomplishedwhat I aimed at; I have constructed a machine which can fly." I hope this will lay to rest a controversy which was sad, andnone of my making. The whole story in detail will, when I can get time for putting it in final shape and having it duplicated,be placed in the Library of the Royal Aeronautical Society for those who wish to read it. TCEA AERODYNAMICS COURSE APPLICATIONS are now being received by the Training Centerfor Experimental Aerodynamics, Rhode-Saint-Genese, Belgium: for its one-year diploma course in experimental aerodynamics.starting on October 2. TCEA, under the chairmanship of Prof Theodore von Karman, is recognized by NATO and a conJitio°of entry is citizenship of one of the NATO nations. Application forms (which should be returned by March 17) may be obtainedfrom the Director, Training Center for Experimental Aero- dynamics, 72 Chaussee de Waterloo, Rhode-Sainte-G-neseiBelgium. Last June, for the first time, a British student (M1 John Nash, University of London) shared with an American(Mr Richard Tracy) the Von Karman prize for the best sradeK of the year.
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