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Aviation History
1956
1956 - 1244.PDF
390 FLIGHT, 31 August 1956 Napier Eland E. 151 (NEI.3). Rotodyne powerplant. Ten-stage compressor, six'combus- tion chambers and three-stage turbine, the rotating assembly being coupled to an airscrew reduction gear at the front and (via a fluid clutch) a nine-stage auxiliary compressor at the rear. Overall diameter, about 40in (basic, 36in); length, 158.25in; dry weight, 2,350 Ib; mass flow, 31 Ib/sec; pressure ratio, 7:1; maximum power (forward flight), 3,000 e.h.p. (2,800 s.h.p. + 500 Ib) at 12,500 r.p.m. with s.f.c. of 0.624. Napier Gazelle NG.1. Free-turbine helicopter engine. Multi-stage compressor, cannulai-combustion chamber with six flame tubes and independent com- pressor- and power-turbines. Overall height, about 70in; maximum diameter at intake, 33|in; dry weight, restricted; mass flow and pressure ratio, restricted; maximum rating (5-min), 1,260 s.h.p. (net residual thrust, 260 Ib) at 20,400 compressor r.p.m. and output- shaft speed of 3,000 r.p.m.; one-hour rating, 1,100 s.h.p. at 19,800 r.p.m. (output, 3,000 r.p.m.); con- tinuous, 920 s.h.p. at 19,000 r.p.m. (output, 3,300 r.p.m.). Other ratings are NG.2 (1,650 s.h.p.), NG.3 (1,800) and NG.4 (2,000). mo oi gas irom aeuvery valve, i./:i;; h.p. at 22,600 r.p.m. with s.f.c. of 0.62. Napier ramjet test vehicle. Free-flying test vehicle for supersonic ramjets, with integral ramjet-duct within body. Launched by eight wrap-round rocket boosters. Diameter, about 18in. No details of weight or performance available. Rocket Motors. Possibly the most importantrocket-motor programme at present in hand for British piloted aircraft is that for the de HavillandSpectre. This unit was first announced in 1955 and unofficial reports, particularly in the foreignPress, have stated that the Spectre will in fact be the rocket motor used in the Saunders-RoeSR.53 supersonic intercepter. It has been de- signed for both assisted-take-off use and for thepropulsion of high-speed and high-altitude air- craft. De Havilland's earlier experience with rocketmotors has centred upon assisted-take-off units arranged as self-contained installations completewith propellent tanks pressurized by nitrogen bottles. For the Valiant, D.H. are in productionwith the Super Sprite, which was the first liquid- propellent aircraft rocket motor to pass a Britishtype test. It runs on high-test peroxide which is blown through a metal-gauze catalyst to producea propulsive jet of superheated steam and free oxygen. Into this jet is injected aviation turbinefuel to increase the specific impulse. D. NAPIER AND SON, LTD. London, W.3 Telephone: Shepherds Bush 1220 Eland. Unlike most corresponding productsof Napier's chief competitors, the Eland is a single-shaft engine. Its compressor is of ex-ceptionally fine design and at the time of its introduction was believed to achieve a recordlevel of work-per-stage. Furthermore, such devices as automatic variable-incidence guidevanes and control of maximum temperature by mercury-vapour sensing units have allowed theEland to become an exceedingly tractable and easily-handled unit which should become popu-lar with pilots. It should also be a favourite with maintenance and overhaul personnel, sincethe whole engine can readily be sub-divided into major sections, any of which can be removedwithout disturbing the remainder. Elands for fixed-wing aircraft have been ex-tensively flight developed in a Varsity, Eliza- bethan and Convair 340 and the earlier versions,rated at about 3,000 e.h.p., have been fully type-tested and are virtually capable of carryingfare-paying passengers. A slightly later devel- opment is the NE1.6, rated at 3,600 e.h.p. anda specific consumption of not more than 0.595, made possible by a change in turbine-bladematerial. Later Elands have now been evolved for operation at still higher turbine-inlet tem-perature. The first of these units was the NE1.4 of 4,000 h.p. which has now been on test for18 months. The NE1.5, rated at 4,200 e.h.p., is more powerful than any other engine of itssize and weight known to be running anywhere in the world, and in cruising flight the specificconsumption is expected to be in the order of 0.44, or possibly even lower. A particularly interesting and unusual engineis the Eland installed in the Rotodyne helicop- ter. It incorporates an auxiliary compressorwhich feeds fresh air to kerosine-burning pressure-jets at the tips of the rotor blades. Incruising flight, however, the auxiliary compres- sor is disconnected, leaving the rotor to auto-rotate; all the power is then transmitted through the conventional propulsive airscrew which isalways driven. This engine, known as the £.151, is described beneath the appropriatephotograph; later versions of a similar power- plant are expected to be appreciably morepowerful and will correspond with the hot- turbine fixed-wing Elands. Gazelle. Specially designed to meet the re-quirements of advanced helicopters, the Gazelle has a pressure ratio, turbine temperature andmass flow carefully chosen to form an effective compromise for such applications. Further-more, the engine can be installed in any of a great variety of ways and is particularly slimand of light weight.
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