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Aviation History
1954
1954 - 1305.PDF
582 THE TWO Rs . . . THE TAY Little known in England (though two units of the type were test-flown in a special Vickers Viscount), the Tay was developed in the first instance by Rolls-Royce from the basic Nene design. It has been further improved by die Pratt and Whitney and Hispano- Suiza concerns, which, respectively, hold the American and French licences. In America the engine is known as the J48, and its applications include the Lockheed F-94C Starfire, Grumman F9F-5 Panther and F9F-6 Cougar. Ratings of 6,250-7,000 lb have been recorded without water injection, a power-boost system which increases thrust by about 1,000 lb. Hispano-Suiza Tays have been installed in Dassault Mystere II, III and IV fighters, and the production Tay 250 is for the Mystere IVA. A development of the Tay by die French company is called die Verdon (following the "River" nomenclature) and has a modified compressor widi new guide-vanes, revised flame-tubes and combustion chambers, and new turbine-blades and disc. A special afterburner has been developed for diis engine, which is to replace die Tay in the Mystere IVA. (Afterburning experi ments with both the Derwent and Nene were made some years ago by the Rolls-Royce company.) FLIGHT Avon RA. 14. THE TRENT This was Britain's first turboprop, and the first turboprop in die world to fly. It was on test as early as March 1945, and in September of the same year two units were installed in a Meteor. Experimental work widi the Trent (RB.50) actually dated back to May 1944, when a Welland was equipped widi a spur-type reduction gear and tested for shaft horsepower. The Trent was built solely to gain experience with a unit combining jet and airscrew propulsion, and was merely an early Derwent with reduction gearing and a small-diameter, five-bladed airscrew. THE CLYDE The RB.39 Clyde was a large turboprop designed before die end of die late war. It was remarkable in having a nine-stage axial compressor and a single-stage centrifugal compressor, in addition to two turbines. The forward (high-pressure) turbine drove the centrifugal blower, and die rear (low-pressure) turbine the axial compressor and contra-rotating airscrews. The Clyde was the first turboprop to pass its full civil and military type-tests. Its first tests were run at 2,500 s.h.p. and diis was later increased to 3,020 s.h.p. Subsequent ratings were 3,500 e.h.p., 4,200 s.h.p. and 4,500 e.h.p.; these last proved that die reduction gear was capable of standing gready increased overloads. The Clyde was flown only in die Westland Wyvern strike fighter. THE AVON The Avon is, in effect, die modern Merlin and, like die Merlin, it had its early troubles; but it is now firmly established as one of die most reliable aero engines of all time. Originally designated AJ65 (signifying an axial unit of 6,500 lb thrust), it went into production during 1950 for the English Electric Canberra bomber. For the historical record, the proto type RA.2 weighed 2,400 lb and gave 6,000 lb dirust, while die production RA.3 was 125 lb lighter. The second basic type to be built in series was die RA.7, which, in 1952, became the pro genitor of a 7,500-lb dirust family of Avons. The first of the series with all-weather protection, the RA.7 had a power/weight ratio even better dian diat of die original production engines, not withstanding die fact diat it had been restressed to accept die loads imposed at transonic speeds. The RA.7R (the suffix "R" denotes that reheat, or afterburning, is fitted) delivers 9,500 lb static dirust at sea level, and an offshoot of die same family is die civil 500 Series, die 503 being die engine of die Comet 2. The latest series of Avons is headed by die RA.14, which first ran in 1952. These newest Avons are considerably redesigned and, aldiough no detailed description is permissible, it can be seen that die RA.14 has a longer compressor dian its fore runners, and that it also has a true annular combustion chamber— the latter, no doubt, in order to accept the tremendous mass flow without increasing "hoop" diameter. The R.A.14 appears to be intended for installation in die wing (it is known diat it powers the Vickers-Armstrongs Valiant B.l), and every effort has been made to reduce depth to a minimum.
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