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Aviation History
1960
1960 - 1633.PDF
FLIGHT, 2 September 1960 353 Olympus 27 Viper 11 BRISTOL SIDDELEY ENGINES LTD Mercury House, Knightsbridge, London SW7. Telephone: Kensington 7090 BS.53 Since 1957 the design team at Patchway, Bristol, has been intensively developing this engine as the powerplant of the Hawker P.1127. This is the first VTOL combat aircraft in the world and its engine is likewise unique in that it is the only powerplant designed from the outset to provide propulsive jets which can be rotated to provide either lift or forward thrust. Essentially the BS.53 consists of the compressor, combustion system and turbine of an Orpheus, with an additional low-pressure turbine driving through an independent central shaft to the first three stages of an Olympus compressor. The latter serves two functions: its inboard portion supercharges the remainder of the engine and its outer portion provides a large mass flow of air ducted outboard on either side of the basic turbojet compressor. These streams of cold air are discharged through a nozzle on either side of the engine which can be swivelled to direct the resultant thrust at any angle between horizontally to the rear and vertically downwards; and the discharge of hot gas from the rear of the engine is similarly ducted to a pair of lateral swivelling nozzles. In conjunction with a compressor-bleed jet stabilization system the BS.53 thus provides a resultant thrust capable of taxying the P.1127 conventionally, lifting it off the ground vertically, flying it as a conventional high-speed aeroplane and setting it back on the ground again with no forward speed. The BS.53 has been running for a year and is being supported under the Mutual Weapons Development Programme. BS.75 Starting with a direct commercial version of the BS.53—the BS.58, weighing 2,6001b and having a thrust rating of 14,5001b—Bristol Siddeley have evolved the BS.75 as an optimum powerplant for a range of short-haul transports and other aircraft. The by-pass ratio is approximately 1.7 and the total flow through the fan about 2001b/sec; design rating is initially 7,3501b and the corresponding specific consumption about 0.5. The last figure is lower than any s.f.c'. previously announced for a turbojet, yet the design of the engine is such that it should rapidly reach a high degree of reliability and long overhaul life. It has been chosen for the BAC-107. Olympus The original BE.10 Olympus was the first two-spool turbojet in the world, and it ran in 1950 at 9,1401b thrust. Today the BO1.21 has a dry rating of 20,0001b, and another version of this superb engine has a maximum rating of 33,0001b when fitted with Bristol Siddeley Solar fully variable reheat. It will doubtless be an engine of this type which will power the twin-engined British Aircraft Corp TSR.2 for the RAF and it has been stated that variants of the Olympus are suitable for military and commercial operations at Mach numbers up to 3. Large numbers of earlier versions are in service as the powerplant of the Vulcan (13,5001b Mk 104 and 17,0001b Mk 201). Orpheus Large numbers of these exceptionally simple and reliable turbojets are today in use in all parts of the world. The most common variants are the Mk 100 (4,2301b thrust for the Folland Gnat T.I for the RAF), the Mk 701 (4,7001b for Gnat fighters for India, Finland and other countries), the Mk 803 (5,0001b for the Fiat G.91 for several NATO air forces) and the Mk 805 (4,0001b for the Fuji T-1A). The latest Orpheus is the BOr.12, type-tested at 6,8101b dry and capable of being fitted with a simplified reheat system boosting the thrust to 8,1701b. The Orpheus is being manufactured under licence in Germany, India and Italy, and other countries are engaged in negotiations. Ramjets Large numbers of Thor ramjets are today in service as the powerplant of the twin-engined Bloodhound surface-to-air missile. These 15.75in units have reached an outstanding degree of reliability and operate on normal aviation kerosine. Last month the company announced the existence of the larger BSRJ.824 engine, suitable for military and commercial propulsion at high supersonic speeds. Rocket Engines Having cut their teeth on the Snarler and Screamer for manned- aircraft applications, Bristol Siddeley's power division at Ansty near Coventry is in production with die Gamma, a packaged unit weighing 7001b with four gimbal-mounted chambers each rated at 4,0001b at sea level on HTP and kerosine, and on a new engine named Stentor. The latter, which is in production as the powerplant of the Blue Steel stand-off bomb, also operates on HTP and kerosine and has two chambers, both of which are rigidly mounted. The larger appears to have a thrust of around 16,0001b and the smaller may have a thrust one-quarter as great. Viper Conceived as 1,6401b short-life engine for missiles and drones, the Viper is today giving thrusts up to 3,2401b, and even more advanced models are in the projectst age. The most widely used version is the Mk 101, used in the Jet Provost T.3 at a rating of 1,7501b. Their performance and service has been outstanding. Virtually a scaied-down Sapphire, the 2,4601b ASV.ll is in production for the Jindivik 3 target and Macchi MB.326 trainer and will power the RAFs Jet Provost T.4s. Orpheus S03 BS.75 BS.53
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