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Aviation History
1956
1956 - 1241.PDF
FLIGHT, 31 August 1956 387 Bristol Olympus 102. Split-compressor turbojet. Multi-stage low-pressure and high- ehTmbeerw?ti;PtreShOrS n by indePendent ™V<™ stages and annular combustion chamber with ten burners. Diameter, 40m; length, about 125in; dry weight about 3 700 Ib equipped; mass flow and pressure ratio, restricted (reported to be 165 Ib/sec and 10-1 on the earlier Mk 101); maximum thrust, 12,000 Ib dry (r'p.m. and s.f.c, restricted but reported to be 6,500 l-p. and 0.79 on the Mk 101). Bristol Orpheus (BOr.3 rating). Single-shaft turbojet. Reported to be seven-stage compressor, annular combustion chamber and single-stage turbine. Overall diameter, 32.4in; length as shown (with jet pipe), 150in; dry weight, about 750 Ib; mass flow and pressure ratio, restricted; maximum thrust, 4,850 Ib, reportedly with s.f.c. of 0.99. An afterburning version of this engine is being developed. ^f^K^ow^ Orpheus. Bristol Aero Engines can be ex-ceedingly proud of the fact that, although the design of this trim, medium-sized turbojet wasonly begun (as a private venture) in 1953 and prototypes have run for only 19 months, it hasalready completed over 5,000 hr of development testing, has passed various type tests at steadilyincreasing ratings and has flown at supersonic speed and at altitudes in excess of 50,000ft. Thefirst full type test was actually completed five months from the first bench run and the latesttype-tested rating is already higher than that required by the original applications. Presentdevelopment running is now going ahead at still higher ratings and there is no reason to doubtthat the basic Orpheus will be capable of eventually yielding thrust of the order of 6,000to 7,000 lb. Already such progress has been rewarded byselection of the engine for a variety of new or projected types of aircraft, including machineswhich are the subject of important NATO pro- grammes. At the time of going to press the fulllist of such applications comprised: Folland Gnat, Fiat G.91, Aerfer Ariete, DassaultEtendard VI, Breguet 1001 Taon, the Yugoslav Ikarus B.12, the Spanish Hispano H.A.300 andthe Japanese Fuji FIT-1. Certain of these air- craft have trainer applications and it is reportedthat a special lightened version of the Orpheus will be available for such duty. Zeus. Although no engine of this name hasever been officially announced as being under current development at Bristol, reports of theexistence of such a unit are appearing at fre- quent intervals. All speak of it as a high-thrustturbojet reported to be of two-spool design and giving a thrust between 12,000 and 20,000 lb. Proteus. At the present time this is theworld's only example of a fully-developed large commercial turboprop. Although the firstProteus ran nine years ago, the present engines are completely redesigned and are exception-ally fine examples of aircraft-propulsion machinery capable of giving thoroughly reliableservice for many years. It has a completely un- restricted C. of A. for passenger carrying andis scheduled to start to earn money on B.O.A.C. routes as the powerplant of the Britannia inOctober. An unusual feature is its free-turbine layout,i.e. the compressor and its associated high- pressure turbine is mechanically independentof the power turbine and reduction gear to the airscrew. Standard equipment includes Ultraelectric temperature control, hot-air de-icing, provision for compressor bleed for cabinpressurization and for the tapping of turbine gas for airframe de-icing, auto-synchronization, adouble-helical reduction gear incorporating a hydraulic torquemeter, and an overspeed de-coupler for the power turbine to guard against any failure of the drive to the airscrew. The latter unit is a de Havilland product withfour hollow steel blades and a diameter of 16ft. Total test hours on the earlier Proteus 600totalled 16,836 on the bench and 2,411 in flight; to this can now be added 22,600 bench hours and20,283 flight hours on the redesigned 700 series, of which nearly all the flight-time has been in theBritannia. All this development has been aimed specifically at commercial service. A majortrouble, only recently encountered, has been ex- tinction of combustion during flight thioughexceptionally heavy icing conditions, but exten- sive B.O.A.C. and Bristol testing has nowestablished the cause of the phenomenon. Remedial action has been taken and B.O.A.C.already have a number of engines modified to the appropriate standard. Present B.O.A.C. Britannia 102s are poweredby the Proteus 705, which is rated at a take-off power of 3,480 s.h.p. (3,900 e.h.p.) at compres-sor r.p.m. of 11,700. This engine exceeds the original requirements of these early-production
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