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Aviation History
1960
1960 - 0368.PDF
Aero Engines i960 Alvis Leonids* 531 Supercharged and geared nine- cylinder engine. Bore and stroke, both 4.8in; swept volume, 783 cu in; dry weight, 8601b; max racing, 650 h.p. at 3,200 r.p.tn. with 8lb/sq in boost at 2,000ft, with consumption of 468-SO0lb/hr; max cont, 585 h.p. at 3,000 r.p.m. with 6.5lb/sq in boost at 2,S00ft, with consumption of 392-418lb/hr. Blackburn A.129 Mk J Turboshaft engine. Com- pressor with two axial stages followed by single centrifugal stage, annular combustion chamber, two- stage compressor turbine and single-stage power turbine. Max diameter, 20.062in; length as depicted, 62.66in; dry weight, 3901b; max rating, i.s.a., 968 s.h.p. + 93lb thrust at 35,000 compressor r.p.m. and 30,000 power-turbine r.p.m. with s.f.c. of 0.681 Ib/hr/s.h.p.; max cont, 815 s.h.p. + 82lb at 34,000/28,100 r.p.m. with s.f.c. of 0.718. 368 April 1959, the complete organization has shaken itself down, and the two main branches, respectively located in Coventry and Filton, are committed to substantial programmes embracing a wide range of types of prime mover. The following review of the company's aero engines casts no distinction between units of Coventry or Bristol origin. BE.S3 During' the past three years the former Bristol engine design staff have applied the major part of their creative energy to a series of double-flow engines which may variously be described as turbofans, by-pass turbojets or ducted-fan engines. In the initial announcement of the BE.53, the first of the family, it was said that this engine can provide both direct lift and thrust, and that its thrust/ weight ratio, "higher than that of any existing turbojet," makes possible the design of VTOL and STOL aircraft of high performance. Alternatively, the cold fan air may be used for flap-blowing or for control of the boundary layer over an aeroplane. Owing to the fact that the BE.53 is a military engine, few details may yet be published, but one is justified in concluding that it is the engine selected for the Hawker P.I 127 VTOL strike/fighter, and that it is therefore in receipt . of financial assistance from the USA under the Mutual Weapons Development Programme. In the drawing (this page) the high-pressure assembly has been shown in solid black. This complete unit is essentially that of the Orpheus turbojet, and it is of great importance to the time-scale of the engine that so critical a component should already be fully developed. Even the low-pressure system (shown shaded) owes something to other Bristol engines, in particular the Olympus. The by-pass (cold/hot) ratio is very high, and is doubtless similar to that of the BE.58. The cold flow is Bristol Siddeley Olympu* BOI.7R Two-spool turbojet with afterburner. Inspection shows that there is a five-stage low-pressure compressor, seven-stage high-pressure compressor, can-annular combustion chamber with eight flame tubes, single-stage h-p. turbine, single-stage l-p. turbine, fully variable afterburner and multi- position nozzle. Overall intake diameter, 36.55in: length, 295.64in: max rating. 24.0001b; type-tested dry rating, 17,0001b. The weight of the non-reheac engine has been stated to be 3,6O0lb and the s.f.c. about 0.80. Brirtol Siddeley BE.S3 Military lift/thrust turbofan. The diagram below has been published by Bristol Siddeley Engines and, although not directly associated with the BE.53, provides a clear indication of the con- figuration of this engine. Two-stage low-pressure fan discharging through lateral ducts with swivelling nozzles, seven-stage high-pressure compressor, annular combustion chamber, single-stage high-pressure turbine, two-stage low-pressure turbine, and jet discharge through lateral ducts with swivelling nozzles. Approximate overall diameter, 46.5in (more than 60in over lateral ducts); length, approximately 180in; weight, about 3,0001b; aggregate mass flow, about 300lb/sec with cold/hot ratio of 2; max rating, at least 15,0001b. FLIGHT, 18 March I960 discharged through lateral ducts, and the pro- pulsive nozzle from each can be turned through any angle between directly downward and directly rearward in order to provide lift or thrust. In a like manner, the hot efflux from the remainder of the engine is ejected in a bifurcated trunk with swivelling nozzles. In a recent paper, *sttmmarized ~m our "issue of January 1, Dr S. G. Hooker, Bristol Siddeley*s technical director (aero) listed six advantages of an engine of this character: "It can be mounted horizontally in the fuse- lage of a single-seater aircraft in a conventional manner; the jets can always be directed rear- wards, and the aircraft used for conventional take-off and landings; the engine can be started, tested and the machine taxied, with the jets directed horizontally rearwards, obviating problems of ground erosion and debris enter- ing the engine during these phases; for short take-offs (say, 200yd) the aircraft can be accelerated with the jets directed rearwards, and then the nozzles can rapidly be deflected down- ward, to, say, 60°, when 87 per cent of the thrust of the engine will be given in lift, and half the thrust of the engine will still be avail- able for horizontal acceleration. In such cases the aircraft will clearly sweep its debris behind it well away from its own intakes; even for vertical take-off the engines can first be opened up to full power, and then the nozzles rapidly deflected vertically to give the minimum time for jet erosion and debris to be thrown around; combining, as it does, both lift and thrust in one engine, the BE.53 keeps the maintenance and logistic problems due to dispersal to a minimum." It may also be noted that an aeroplane powered by a BE.53 can operate in a conventional manner when a runway is avail- able and also that the jets may be deflected forward in flight in order to give reverse thrust for very high deceleration, steep descent and short (or vertical) landing. No other aeroplane powerplant combines such qualities as does the BE.53, and it should spawn a prolific family. BE.58 An example of this commercial engine was exhibited at the 1959 SBAC dis- play. It is essentially a commercial BE.53, and inspection of the display mock-up showed that the original lateral fan ducts had been combined to give a single annular outlet. For airline applications there is no requirement for swivelling nozzles, and accordingly in the BE.58 both the hot and cold flows are taken to propulsive nozzles at the rear. Thrust-reversal can most conveniently be done when all the jet is contained in a single final nozzle. Intern- ally the 58 is probably identical to the 53. Bristol Siddeley have stated that, although it is not an adaptation of an existing unit, "a large number of components . . . are identical or closely similar to those used in early engines which have completed tens of thousands of hours in service." Its development may there- fore be expected to progress rapidly. Under cruising conditions the BE.58's specific consumption is claimed to be "at least 10 per cent lower than the best turbojets," and that under static or climb conditions it shows up even more favourably. Like the* BE.53, the thrust/weight ratio is competitive, and the jet noise level should be "some 10 decibels below the best straight jet engine and 15 decibels below the average turbojet." Unlike most engines, the mock-up exhibited at Farn- borough carried all its accessories around the upper part of the compressor casing. The equipment included a Dowry fuel system, Rotax low-pressure air starter, twin alterna- tors, Dowry hydraulic pump, fuel /oil heat exchanger and, to port, the oil tank. BE.61 Rated at some 7,0001b thrust, this middle-sized member of the fan family is specified for the projected Hunting H.107 transport. No details of the engine are avail- able. BE.72 Bristol Siddeley recently published a diagram showing the improved ground noise-
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