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Aviation History
1960
1960 - 1632.PDF
352 FLIGHT, 2 September British Engines 1960 1 Leonides 531 I j... tefow, Turmo 603 in P531 kik 0 Left, XoUs-Royce KB.141 development engine in QSSGMDty Leonides Major 702 ALVB LTD Holy head Road, Coventry. Telephone: Coventry 25501 Leonides Although the earlier types of Leonides, with a stroke of 4.41in, are still in production, by far the greater pan of the company's effort on this fine nine-cylinder piston engine is concentrated upon the long-stroke (4.8in) variants such as the Mk 531. The new engines have longer pistons and are generally strengthened to permit them to operate at increased powers. The 531, which weighs 8601b dry and has a swept volume of 783 cu in, is rated at 650 bJi.p. at 2300 r.p.m. with 811b/sq in boost at 2,000ft. Maximum continuous power at 2,500ft is 585 b.h.p., the corresponding consumption being around 4001b/hr. Installed in the Twin Pioneer Series 3 these engines confer an increment of additional performance which is especially valuable in operations from hot or high airfields. A considerable number of RAF Twin Pioneers are at present being fitted with the new engines. LeonMes Major Production of the 14-cylinder two-raw Major is continuing, the last mark to be produced being the 702, derated to 750 b.h.p. to suit the transmission of the Westland Whirlwind helicopter. BLACKBURN ENGINES LTD Brough, Yorks. Telephone: Brough 121 Nimbus Previously known as the A. 129, this free-turbine engine has been evolved from the earlier gas turbines derived from the French Turbomeca family and incorporates several major portions which are common to the earlier units. Nevertheless the addition of a two-stage axial compressor upstream of the steel centrifugal impeller, and of a second stage to the compressor turbine, have changed the performance of the engine out of all recognition; compared widi the Turmo for example, the Nimbus gives more than twice as much power and has significently lower specific consumption. An annular air intake is employed (for the first time in a Blackburn engine), incorporating an integral oil tank, and immediately behind it is a wheelcase on which are mounted most of the accessories. Other features include variable inlet guide vanes and a torquemeter. The free turbine drives to the rear and the exhaust is taken out obliquely past the reduction gearbox. The complete engine weighs 3901b and a typical raring is 968 sJi.p. with s.f.c. of 0.681. The gas-producer portion of the Nimbus was run as a turbojet in July 1958, and the complete A.129 prototype was bench tested in August of that year at 840 s.h.p. Development is being sponsored by the Ministry of Aviation, since the engine will power the production Westland Sprite helicopter for the British armed services. A simulated type test has already been run successfully, and Blackburn expect to sell the Nimbus for less than £10,000. Turmo This free-turbine unit has twin intakes and exhaust trunks (one on either side) and is the powerplant of the Westland P.531 Mk 0 helicopters currently being evaluated by the Royal Navy. The engine weighs 2751b and is rated at 400 s.h.p. A.129 Nimbus
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