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Aviation History
1956
1956 - 1245.PDF
FLIGHT 31 August 1956 391 Power is delivered to the rotor through agearbox driven by a mechanically independent power turbine, behind which the exhaust gasescapes through bifurcated stack-pipes. Single- lever control is provided, with automatic com-pensation for variations in ambient temperature and pressure and turbine-inlet temperature,and with maximum and minimum torque limi- tation. The use of a free power-turbine isparticularly advantageous in allowing both the engine and rotor to adjust their r.p.m. inde-pendently. Prototypes have passed their 25-hr flight-approval test, and both the design powerand specific consumption were bettered during the initial calibration running. The Gazelle isalso likely to find fixed-wing applications. Oryx. In this unique engine all the power ispushed out in the form of a flow of gas at a temperature and pressure suitable for helicoptertip-jet propulsion without the use of tip-burn- ing. The Oryx has a single rotating assemblycomprising an axial compressor, a turbine and an auxiliary compressor. The latter feeds freshair which is mixed with the exhaust gas to give an output at rather less than 700 deg K at about23.5 lb/sq in absolute. The engine has been fully type-tested at progressively increasedratings and has greatly exceeded original design figures. Ramjets. For nearly six years the NapierFlight Development Establishment at Luton have been primarily responsible, under sub- contract from the National Gas Turbine Estab-lishment, for the development of a test vehicle powered by a ramjet arranged integrally withthe fuselage. The first vehicle was fired in October 1950 and steady progress has sincecharacterized each succeeding vehicle. The latest patterns have a pitot intake at the frontof the integral ramjet-fuselage, a slab-sided centre-body spanning a diameter within theduct and housing the bag-type fuel tanks and control system, together with the associatedelectronic gear and the fuel pump driven by ram-air turbine. Launching is by means ofeight rocket boosters wrapped around the rear of the vehicle in the manner used in someguided-missile programmes. Earlier this year it was announced by Napierthat their ramjet test vehicles had flown to greater altitudes than any other British ramjetsand that they had also reached high supersonic Mach numbers while showing very satisfactoryperformance. Rocket Motors. At the 1955 S.B.A.C. ex-hibition Napier were allowed to exhibit the com- bustion chambers for two rocket motors, one ofwhich was designated N.R.E.17. The production type of chamber was fabricated from sheet steeland had a thrust of approximately 2,500 1b using high-test peroxide and kerosine. Earlier thisyear the existence was announced of the Napier Scorpion rocket motor which is being air-testedin a Canberra, the installation being made at the rear of the bomb bay. No details of theScorpion may yet be published. ROLLS-ROYCE, LTD. Nightingale Road, Derby Telephone: Derby 42424 Rolls-Royce Tyne 506 (RTy.1). Two-spool turboprop for transports. Multi-stage low- pressure compressor, multi-stage high-pressure compressor, single-stage high-pressure turbine, three-stage low-pressure turbine and cannular combustion system. Overal diameter. 40.5in; length. 100.25in; dry weight, equipped 2 023 Ib; mass flow, over 4 b/sec pressure ratio 13:1; maximum rating, 4,695 e.h.p. (4,220 s.h.p.) at15,250 r.p.m.; typical fasTcrutse rat ng at 25,000ft at 370 kt, more than 2,640 e.h.p. at 13,500 r.p.m. with s.f.c. of under 0.411. Roll,.Royc. Dart 525 Dart. For more than three years this famousturboprop has been the only gas turbine in scheduled airline service. As the standardpowerplant of the Viscount, it is now employed in all parts of the world and has logged a totalof nearly 1£ million hours and has established itself as a unit of quite outstanding reliability.It was originally designed at the end of World War 2 and employs a unique layout which isdescribed in the data beneath the line drawing. The original versions were rated at 1,000 h.p.but this had increased to 1,547 e.h.p. by the time that the first production engine entered servicewith B.E.A. in April 1953. Present production is centred mainly uponthe Dart 510 rated at about 1,750 e.h.p. and embodying several design changes to increasethe service life and improve the operating economy. Early next year the Dart 520, witha three-stage turbine, will come into use for certain types of long-fuselage Viscount. Thisengine, of which one version is illustrated, delivers a power of the order of 2,000 e.h.p. withstill-further-improved economy. Initially it will be cruised at a conservative rating of 13,400r.p.m. in order to gain experience before going on to the full rating of 14,000 cruising r.p.m. The ultimate Dart at present envisaged is theRDa. 10 rating in which a very considerable increase in power has been made possible bythe adoption of advanced "back-end" techniques involving cooled turbine blading. In the Vis-count the RDa. 10 and its developments will be power-limited to 1,800 s.h.p. but will main-tain this power up to virtually all normal con- ditions of airfield, altitude and temperature,thus making water/methanol injection (standard on earlier Darts) largely superfluous exceptunder the most arduous conditions. In the Friendship the later RDa. 10s. will be clearedto operate at no less than 3,150 e.h.p. Tyne. Not only are the thermodynamic design points of this turboprop as advanced as those of any other gas turbine in the world, but
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