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Aviation History
1953
1953 - 1173.PDF
FLIGHT, 4 September 1953 BRITISH POWER UNITS 1953 Napier Viand NEWEST arrival in the medium-power turboprop class, the Napier Eland nevertheless has considerable background in design experience. It is an axial unit of very small dimensions and very low weight (approx. \ lb. per h.p.) for its 3,000 s.h.p. output. It is designed to drive a single c.s. airscrew. The specific consumption in par ticular is attractive to aircraft designers, a figure of 0.49 at 350 m.p.h. T.A.S. and 30,000ft being quoted. It has six combustion chambers, while recently released is the in formation that a ten-stage compressor and three-stage turbine are employed. A test-bed installation of two Elands in a Varsity is in hand. Elands with additional air compressors are named to provide the power for the recently ordered Rotodyne helicopter. Napier Nomad MORE light has recently been cast on Napier's Nomad developments. The moderate performance of early experimental units has been far surpassed, and al though much work remains to be done, the truly remark able specific consumption of around 0.33 lb/e.h.p./hr over a range of operational conditions sets it in a class apart— even from the American piston engines ingeniously adapted to recuperate exhaust energy. The Nomad NNm.6, designed from the start as a compounded unit, offers unique advantages for long-ran^e aircraft and may prove to be one of the outstanding post-war developments in power units. Comprising a 12-cylinder, supercharged opposed-piston diesel engine, serving as both primary power source and gas producer for the exhaust turbine, the Nomad has an unusual form of gear-box for the coupling of turbine-shaft power via a quill shaft to that from the main crankshaft. The main reduction gear carries the combined power to the single airscrew. Rolls-Royce Avon SINCE the 1952 S.B.A.C. Exhibition security has been slightly relaxed on the Avon family, which are with out doubt among the few oustanding turbojets of the world. The recent performances of certain aircraft with Avon power have clearly indicated the development of more than the officially announced figure of 6,500 lb thrust, and now the RA.7, RA.7R and RA.14 can be men tioned together with their thrust figures of 7,500 lb, 9,500 lb with reheat, and 9,500 lb basic respectively. The latter unit has a specific consumption of 0.84 and the RA.7 of 0.92. These remarkable type-tested thrust figures are achieved from units of very modest weight and dimen sions and with life and reliability of such an order as al ready to be acceptable by commercial standards. The RAJ of 6,500 lb thrust as fitted to the B.O.A.C. Comet Series 2 is already approved for 600 hr between over hauls. This unit weighs 2,440 lb and has a specific con sumption of 0.90. Avons up to and including the RAJ have eight large combustion chambers. NOMAD S Width .. Height .. Length .. Frontal area Weight .. Maximum power .. 58.25m 148 cm 49.25m 125 cm noin 302 cm 19.IS »q ft 1.78 «q m 3,580 lb 1614 kg 3.135 3179 cv. pt.e. e.s.h.p.
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