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Aviation History
1957
1957 - 1025.PDF
26 July 1957 115 Proteus. It is unfortunate that the first applications of the Proteusconcerned the Brabazon and Princess, since these projects gave the engine a reverse-flow layout and caused much time to be wasted oncoupled projects, and also held up the pace of development. A new series of Proteus was run in 1952 as a Britannia powerplant, and thisengine is now by far the most highly developed large commercial turboprop in the world. The Proteus was last described in our issue of August 12, 1955.Equipment includes Ultra electric temperature control, hot-air de-icing, compressor bleed for cabin pressurization, auto-synchronization, auto-decoupling by an overspeed senser on the power-turbine drive and a double-helical reduction gear incorporating a hydraulic torquemeter. Present Britannia 102s are powered by the Proteus 705, of whichproduction is complete. Rated at 3,480 s.h.p., or 3,900 e.h.p., these engines have completed some 50,000 hr in scheduled B.O.A.C. service,backed up by approximately the same time in development running. In spite of its mechanical complication it is an extremely reliable engine;it is normal practice to work a Britannia service to Johannesburg and back to London (13,600 miles) without once opening the cowlings, andeven after the round-trip the maintenance man-hours do not reach double figures. The present overhaul life is 850 hr, and a furtherincrease is in prospect. Giving a maximum of 4,120 e.h.p., the Proteus 755 powers the heavierBritannia 300/310 series, and is in full production. When the initial flying of the Britannia 312 revealed a small percentage deficiency inrange, minor improvements were made to the engine to reduce the specific consumption and raise the power, and the results of these modi-fications are now being explored. Present indications are that the brochure performance of the long-range Britannia has been more than restored. Orion. Fully described in our issue of October 26, 1956, the Orionwas designed to achieve a cruise power of 3,500 h.p. at 30,000ft with a fuel consumption at least as good as that of the most efficient pistonengine. The engine was also planned as the first derated, or super- charged, gas-turbine, in that it is not a full-throttle engine at sea level.The fuel flow is restricted below 20,000ft to hold output at 4,400 s.h.p., a rating admirably suited to a range of transport aircraft, includingadvanced types of Britannia such as the series 450. Thus no penalty on aircraft performance is imposed by airfield height or ambient temperature. Orion development is continuing, on schedule, with bench running toprove mechanical reliability and flight trials in the original Britannia prototype. Engines to production standard should be running at the endof this year. The Orion is the powerplant chosen for the Canadair CL-44 military transport, ordered by the R.C.A.F. for delivery in 1959. Piston Engines. The only unit still in production is the 18-cylinder,sleeve-valve Centaurus, for the Beverley transport. This engine was described in our 1956 review, and a direct-injection version was describedon November 16 last. <L Bristol Thor BT.1. Supersonic ramjet. Fixed-geometry double-shock intake,circular-section body housing diffuser and combustion chamber, centre-body housing fuel system, convergent/divergent propelling nozzle. Overall diameter,about 16in; overall length, about 109in; weight and performance, restricted. It has been stated that a theoretical horse-power of about 90,000 could bedeveloped at Mach 3 at sea level. Ramjets. At present all Bristol ramjet development and productionis undertaken for the M.o.S. and very little detail can be published. It can, however, be said that the company are one of the world leaders inthis field, and have described their ramjet fuel systems as unexcelled. Notes on the company's history in this field were published in ourissue of August 10, 1956. In the past, by far the most important unit has been the Thor, illustrated. Development of this powerplant waseffected with a supersonic vehicle named Bobbin, driven by twin Thor engines after initial launching by rocket boost motors. All aspects ofThor's behaviour were proven during numerous test-firings in Australia, and 100-per-cent reliable operation has now been assured. Thor is nowin production on a very large scale as the powerplant of the Bristol/ Ferranti Bloodhound surface-to-air weapon, chosen by the R.A.F. asthe standard anti-aircraft missile for home defence. D.H. The de Havilland Engine Company, Ltd., Leavesden Aero-drome, Watford, Herts. Paradoxically, although official support has for some time been withdrawn from the biggest D.H. engine, the company'soverall business prospects are anything but bleak. As a result of exten- sive and painstaking development de Havilland have prepared a rangeof powerplants which have gained, or promise to gain, very wide accept- ance in existing and projected aircraft and related systems. Since 1927 de Havilland have been renowned as makers of low-powerpiston engines under the family name of Gipsy. The latest members of this family remain in production for fixed-wing aircraft and heli-copters. Centrifugal turbojets, of which several thousand have been delivered since 1943, are gradually being run down in production, butwill continue to be built for a considerable period. The new family of axial engines is progressing favourably and is nearing the productionstage; the Gyron Junior, in particular, bids fair to become a unit of the first importance. Rocket motors include the Super Sprite, in full pro-duction as an a.t.o. unit, and the highly efficient Spectre. Ghost and Goblin engines have been widely exported and builtabroad, and for some years a technical association has been maintained with G.E. (U.S.A.). Apart from engines the company have developedreverse thrust, flap-blowing and jet-dene ;tion mechanisms and a wide range of shaft-drive units running on high-test peroxide. Sub-contractwork is being done for other engine firms. Headquarters of the Engine Company—which is, of course, one ofthe many partners in the D.H. Enterprise—is located in a new building on the airfield at Leavesden, near Watford, Herts. Also at Leavesden isthe main factory for the production of piston engines, gas turbines and rocket motors, together with the principal overhaul base. At the formerH.Q. at Stag Lane, Edgv/are. Middlesex, is the Engineering Division, responsible for prototype design and research. Chief engine-test centreis the ad hoc colony on the north side of the D.H. Aircraft airfield at Hatfield, Herts. Administered by Stag Lane, this facility can test aGyron Junior at conditions appropriate to Mach 1.25 at sea level, using a Gyron to provide power, and many other facilities are provided in theHalford Laboratory. A Mach 2 tunnel is a particularly valuable tool, especially in view of the company's heavy commitment in the field ofsupersonic propulsion. At Harlow, Essex, a completely new plant is being established for the design and development of new motors by theRocket Division. Finally, the London D.O. is handling nuclear projects. Ghost. All Ghost engines now being built are of the final series105. Previous marks were described in our "Aero Engines" issues of 1954 and 1956. Compared with the earlier Ghosts the 105 gives higher performance,by virtue of increased r.p.m. and turbine-inlet temperature. The tur- bine nozzle guide vanes are hollow and cooled by compressor dischargeair, and the turbine rotor has Nimonic 95 blades retained in revised root serrations with pin fixing. Another design change is the adoption offully floating nozzle boxes downstream of the combustion chambers. The new fuel system is by Lucas, and incorporates a single D-typepump; top-speed control is an electrical system by Lucas-Ultra. Production units are delivered as Ghost 53 Mk Is to the Royal Navy.They power the Sea Venom F.A.W. 22, and in due course all Sea Venoms will be retrospectively fitted with the engine. Goblin. Previously described in this journal, the Goblin centrifugalturbojet remains in production as the powerplant of the Vampire Trainer. Export Vampire T.55s have the Goblin 35, of 3,500 lbthrust. Similar engines are fitted to Vampire Trainers manufactured in Australia and India. Gyron. Under the direction of the late Maj. Halford the designof this big turbojet started in 1951, with the company designation H.4. For some years previously Maj. Halford, Dr. Moult and their col-leagues had been determining the type of gas turbine which would be required for advanced supersonic military aircraft of the period 1955-1965. They concluded that the optimum form of turbojet should have only a moderate pressure ratio, but should operate with the maximumpossible mass flow and top temperature and also be capable of asso- ciation with an advanced afterburner. Much of the preliminary design work concerned the compressor, andthat of the Gyron is of an advanced form. It comprises seven discs and spacer rings, with diameters which rapidly increase from frontto rear, through-bolted to each other forming a rigid unit. Steel blades are then fitted to the peripheries of the discs, each blade having adouble-lug root which straddles the disc and is retained by a pin. The The Halford gas-dyna- mics laboratory of de Havilland Engines is situ- ated on the north side of Hatfield aerodrome. It is capable of conduct- ing full - scale experi- ments on modern gas- turbine powerplants.
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