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Aviation History
1956
1956 - 0568.PDF
568 FLIGHT Alvis Leonides Major: Herald powerplant in H.P.R.S test-bed. AERO ENGINES 1956 . . . GREAT BRITAIN ALVIS. Alvis, Ltd., Holyhead Road, Coventry. Alone among themajor British engine companies, Alvis are still devoting all their energy to the development of reciprocating engines. They have not madepublic even a hint of a move towards other forms of prime mover. This has probably been a wise policy, in that it has enabled the firmto produce two eminently marketable engines, which are described below. Admittedly gas turbines are beginning to encroach upon the"Alyis power-class" but it looks at present as if the Leonides and the Major will still be in production several years hence. Leonides. Development and production of fixed-wing and helicopterversions of this compact, nine-cylinder radial has proceeded steadily; some 500 have been delivered for the Provost programme alone, andnew installations last year included the Twin Pioneer (two Leonides 503/8 of 570 h.p.) and the Widgeon helicopter. A unique applicationof the engine is found in the Fairey Jet Gyrodyne experimental rotary- wing machine, in which a Leonides drives a centrifugal compressorwhich feeds air to combustion jets at the tips of the large rotor blades. Leonides Major. Using cylinders almost identical with those of thesingle-row Leonides, this engine makes a very efficient and slim power- plant for fixed-wing aircraft and is also being extensively developed fora number of helicopters. One of the most important fixed-wing applica- tions concerns the Herald transport, in which the Majors are containedwithin low-drag cowlings composed of four petals, cooling-air leaving through two gill-panels on each side, with the carburettor-intake under-neath and the oil cooler on top. A similar powerplant has been proposed for the American Frye Safari transport. The drawing shows a left-hand-rotation powerplant developed for the Whirlwind helicopter. Bench time now exceeds 4,000 hr. Two trial type-tests of the fixed-wing Major were successfully run last year and it is expected that pro- duction units will be fully cleared for operation in parallel with theaircraft programmes with which they are associated. The engine first flew in the H.P.R.5 test-bed in March last year. Nine months ago fourMajors took the prototype Herald into the air and it is in this aircraft that most of the hours have been logged, the behaviour generally being emin-ently satisfactory. Another first flight last year was that of the Whirlwind H.A.R.5 and two more helicopter Majors (of a different type) will shortlyfly in the fourth prototype Bristol 173, precursor of the Bristol 191. ARMSTRONG SIDDELEY. Armstrong Siddeley Motors, Ltd.,Parkside, Coventry. As the Hawker Siddeley Group's main Home engine company, Armstrong Siddeley were pioneers of the axial gas tur-bine in Britain and they were also the first British firm to abandon piston- engine development. By the end of 1947 prototypes of every one ofthe company's present engines (with the exception of the small Viper of 1950) were flying, or running on the bench. Each has since beenpainstakingly developed, in most cases to meet particularly arduous requirements, such as those of carrier-based aircraft, fighters and mili-tary trainers. Research, development and pre-production work takes place in Coventry, but bulk production of the Sapphire turbojet is theresponsibility of a subsidiary company, Armstrong Siddeley (Brock- worth), Ltd., in Gloucestershire. During the past decade Armstrong Siddeley have led British develop-ment of "hot" rockets for piloted-aircraft applications, and in 1954 the company established a separate Rocket Division at Ansty, near Coventry,where research and development facilities are steadily expanding. A broad programme of rocket development is being pursued, involvingvarious sizes and designs of motor and several combinations of fuel and oxidant. In view of Hawker Siddeley interest in atomic power (q.v.), includingaircraft powerplants drawing heat from a reactor, it is possible that Armstrong Siddeley may later also become involved in this sphereof activity. Sapphire. For the past two years this excellent turbojet has goneinto wide R.A.F. service in the Hunter and Javelin. Production is centred at Armstrong Siddeley (Brockworth), Ltd., in Gloucestershire,whose total output must now run into four figures. Most of the engines so far delivered have been to the Sa.6 rating (in the bracket 8,000 to 1 uJ Alvis Leonides Major A.L.E.M.1-2. Helicopter engine. Two-row 14-cylinder piston engine mounted at 35 deg (in S-S5) with supercharger and direct drive with cooling fan. Overall diameter, 38.9in (basic engine); length as shown, about S5in; bore, 4.8in; stroke, 4.41in; swept volume, 1,118 cu in; dry weight, approximately 1,000 Ib; maximum rating, 850 h.p. at sea level at 2,900 r.p.m. with 8 Ib/sq in boost. Armstrong Siddalty Sapphire ASSa.7. Single-shaft turbojet. [Multi-stage compressor, annular combustion chamber and mulli-scage turbine. Overall diameter, 37.4in; length as shown, 132in; dry weight (including anti-icing, turbo- starter, high-energy igniters and oil tank), 3,075 Ib; mass flow, and pressure ratio, restricted maximum thrust, 10,5001b at 8,600 r.p.m. with s.f.c. of 0.885. 8,300 lb) but the predominant version at present is the Sa.12. Thelatter is mechanically similar, but employs cast turbine rotor blading which has allowed a valuable increase in turbine-inlet temperaturegiving a rated thrust of 8,500 lb. Early examples of this family of Sapphires were shipped to the U.S.A. and are the subject of a licenceagreement with Wright Aeronautical (<j.t>.). A new family of engines has now been developed which, althoughstill subjea to security classification, exhibits such marked differences from its predecessors as to betray complete redesign. The compressorcasing is longer than previously and the intake annulus area is substan- tially greater, from which it may be concluded that both the mass flowand the pressure ratio have been markedly increased. No Sapphire, incidentally, has ever been seen with v-i. guide vanes or blow-off valves.Other new features are the tapered compressor casing, an advanced form of hot-air de-icing, a fuel-cooled oil cooler and a reduction in thenumber of burners to 24. The excellence of the new engines is emphasized by the fact that,although they deliver a five-figure thrust, their economy is also in advance of that of their predecessors (which were already regarded asexceptionally efficient). The Sa.7, the first unit of the new family, is
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