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Aviation History
1948
1948 - 1141.PDF
JULY 22ND, 1948 A Private Venture FLIGHT ox Gipsy Major engines. We hope to publish some details of this project next week. A large contract has been accepted for the testing of structural materials in order to establish their less-known characteristics. A programme on the effects of corrosion on the physical properties of light alloys, and an assess- ment of the effectiveness of surface protection, is also in hand. One extremely interesting task is the testing and develop- ment of the Gerritsen gear, invented and designed by the company's chief engineer. This is an infinitely variable gear of very simple design, and already the earlier tests have shown great promise. When fully developed and proved, this gear should have numerous applications. As already mentioned, Tiltman Langley Laboratories 109 have much work in hand apart from aircraft, and we have no doubt that acti- vities will in- crease as the firm becomes better known. Hitherto Tilt- man and Lang- ley have pre- ferred to say nothing about themselves, and their work was known to but a few. Now that their existence has been '' officially '' announced, we expect our old friends to be kept busy. (Left) 1. ). Gerritsen, B.Sc, A.F.R.Ae.*., chief engineer, and N. 0. Rowlinscn, B.Sc, A.F.R.Ae.S., project engineer. FIREFLY'S NEW ROLEA CONTRACT from Sweden for a target-towing version of the Fairey Firefly two-seat naval reconnaissance-fighter has been received by the Fairey Aviation Company. These air- craft are fitted with a standard Type B.Mk.IIJB windmill-winch able to stream 7,000ft of cable. They will be used to tow glider and sleeve targets for ground-to-air and air-to-air firing practice, and will be equipped for changing sleeves in flight. This new contract means that the Firefly will now fulfil five distinct duties in service; day fighter-reconnaissance (FR Mk.i, FR Mk.4, FR Mk.5), night fighting (NF Mk.5), anti-submarine patrol (AS Mk.5), operational training and target towing. The Firefly is in service with the Royal Navy, Royal Canadian Navy and Royal Netherlands Navy, and has been chosen for the Royal Australian Navy. Years of valuable work lie ahead of this Griflon-powered two-seater, which bids fair to rival the illustrious Swordfish in adaptability and all-round usefulness. ATOMIC POWERED AIRCRAFT F a paper recently delivered befor£ the Detroit section ofthe Society of Automotive Engineers, Andrew Kalitinsky, Chief Engineer, N.E.P.A. Division, of the Fairchild Engineand Airplane Corporation, gave an extremely interesting sur- . vey of the basic requirements and problems of atomic powersupply for aircraft propulsion. Among the basic types of power plant which can be adaptedto utilize atomic energy, the lecturer cited the closed-cycle turbine of steam or mercury type, the steam being generatedin a nuclear reactor, or pile, by the heat released there. The reactor therefore replaces the boiler of a conventional powerplant. After expansion through the turbine, which drives the airscrew, the steam is condensed and forced back into theboiler reactor by a feed pump. This type of power plant requires the use both of an airscrew and an air-cooled con-denser and these will eventually limit the aircraft speed at which such a power installation can be used.-JC In applying atomic energy to a turbojet, the conventional combustion chamber is replaced with a nuclear reactor. Airis compressed in the compressor and then forced through the reactor where it is heated by convection instead of by com-bustion of fuel. The air then expauds partially through the turbine, enough to provide sufficient power to drive thecompressor, and finally in the jet nozzle where it creates the propulsive thrust. Mr. Kaiitinsky also suggested the use of a reactor to replacethe combustion process in a ram-jet type unit, and then went on to consider the use of nuclear energy for rockets.In a rocket, the highest possible temperature and the lowest possible molecular weight are desired. Normally, since thepropellant is the result of the combination of at least two atoms, its molecular weight will obviously be fairly high; forexample, if hydrogen and oxygen are used, the resultant pro- pellant is water vapour with a molecular weight of 18. How-ever, if nuclear energy is used to provide the high temperature, there is no need for the process of combustion, and very light"propellants like hydrogen, with a molecular weight of 2, can be used. Since the ratio of 18 and 2 is 9, and the square rootof 9 is 3^ the specifia impulse of pure hydrogen at the same temperature is three times that of water vapour. Of the engineering problems, one of the more crucial isthe protection of the uranium in the reactor against corrosion by the working fluid, and, conversely, the prevention of theescape of th.e radioactive fission products from the reactor into the working fluid. This is a problem of diffusion, andas diffusion rates generally go up with increasing temperatures, the development of adequate cooling for the high-temperaturereactor elements is a major problem. Another crucial problem is weight. In an atomic engine,it is necessary to use large amounts of mass to stop the radiations emitted from the fission process. Not only theabsolute weight of the shielded reactor is important, but also its specific weight, and it can be shown that the specificweight of the reactor must be less than, or equal to, the lift/ drag ratio times the ratio of permissible reactor weight toaircraft gross weight. GHOSTLY REALITY : The prototype of the Swedish S.A.A.B. J.29 fighter, powered with a de Havilland Ghost turbojet, is now complete. These views re- yeal some of the many bold design features, notably the undercarriage. A speed of about 650 m.p.h. should be attained. B 29
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