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Aviation History
1972
1972 - 0033.PDF
FLIGHT International, 6 January 1972 Above, Detroit Diesel Allison Model 250-CI8 turboshaft for which Hants & Sussex Aviation operates the European distributorship franchise, including full service support fly at the end of this year, powered by the JT15D-1, and the second aircraft in March 1973 with the JT15D-4. Only competition for the Canadian engine are two new Turbomeca turbofans of geared, variable-pitch fan, con stant-speed design. These are the Astafan, utilising the company's Astazou turboprop/turboshaft as core engine, and the Bastafan making similar use of the Bastan turbo prop. The Astafan first ran in the autumn of 1969 and in April last year flew for the first time in a modified North American Rockwell Hawk Commander, replacing the normal turboprops. Thrust span of this engine is 1,3701b, 6kN to 2,4141b, llkN with water injection. The Bastafan, which has not yet been tested, will initially cover 1,6001b, 7kn to 1,8001b, 8kN, later being extended to the 2,0001b, 9kN category. Both of these engines offer the advantages of a proven gas generator and a constant-speed variable-pitch fan. Both are aimed by Turbomeca at the business-jet and general- aviation markets, especially as retrofit power units for the Hawk Commander and other similar turboprop aircraft. Production versions of the Astafan series can be supplied within nine months of the first order. Variants of the Astafan are proposed as compound engines for high-speed helicopter propulsion. In these, a modified gearbox is incorporated which enables power sharing between the fan and an external power take-off point. Helicopters powered by the Astafan would lift-off with the fan blading in fine pitch, and most of the power of the engine being diverted to the rotor. Once airborne and translating to forward flight, the fan pitch would be increased to absorb most of the engine power, enabling the turbofan to provide normal forward propulsion. In this condition the helicopter rotor would be off-loaded and the responsibility for lift taken over by stub wings. Interest in this dual-mode turbofan/turboshaft form of propulsion is now also being evinced by the major US turbine manufacturers, following interest shown in the configuration by several aircraft companies. Market contenders: United Aircraft of Canada JT15D-1 2,2001b, lOkN; JT15D-4 2,3101b, lOkN. Turbomeca Astafan I 1,3701b, 6kN; Astafan II 1,5651b, 7kN; Astafan III 1,7651b, 8kN; Astafan IV 2,4141b, llkN; Turbomeca Bastafan 1,6001b, 7kN to 2,0001b, 9kN. Left, United Aircraft of Canada JTI5D-I turbofan of 2,2001b, lOkN, production deliveries of which are now being made to power the Cessna Citation 25 CIVIL SHAFTPOWER 5,000 s.h.p., 3,730kW—15,000 s.h.p., 11,185kW THIS is AN essentially disparate, non-competing group of engines extending from the Rolls-Royce Tyne turboprop and Soloviev D-25 turboshaft at the lower end to the mighty and unique Kuznetsov NK-12 turboprop at the top end. In between are projected turboshaft derivatives of the R-R/Snecma M45H and GE TF34 turbofans, (the latter an essentially military engine), together with Lycoming's new 5,000 s.h.p., 3,730kW LTC4V-1 turboshaft/turboprop which is scalable, as the LTC4V-4, to 10,000 s.h.p., 7,460kW. The Tyne, which would appear to have become the definitive turboprop in the West covering the 4,800 s.h.p., 3,580kW to 6,100 s.h.p., 4,550kW bracket, is in limited production at Rolls-Royce and its European licencees (Snecma, Fabrique Nationale and MTU) to power the ASW Breguet Atlantic and also the Transall C-160. Powerwise only, its nearest competitor is the Soloviev engine, which extends from 5,500 e.h.p., 4,100kW to 6,500 e.h.p., 4,850kW and powers the two largest of the Mil range of helicopters, the Mi-6 and the world's largest and heaviest, the V-12. In the latter, two pairs of D-25VFs drive the two 114ft, 35m-diameter transverse rotors. In a class of its own, the 15,000 h.p., ll,185kW Kuznetsov NK-12 series of turboprops are significantly the most powerful shaftpower aero engines in the world. They power the Tupolev Tu-114 and Antonov An-22 transports: in the West the big turboprop has been effectively outdated by the development of high-thrust, high-by-pass-ratio turbo fans. Sneoma is reported to be working on a turboshaft derivative of the M45H, designated M57H and rated in the 8,000 s.h.p., 5,970kW to 10,000 s.h.p., 7,460kW bracket. Interest has been aroused in America in the engine, and a co-operative programme is understood to have tentatively discussed with Pratt & Whitney. Also as a possible heli copter power unit, Snecma is refining the details of the M45R, a derivative of the M45H designed to provide high- pressure air, either hot or cold, for rotor propulsion. Market contenders: Rolls-Royce Tyne RTy20 6,100 e.h.p., 4,550kW. Soloviev D-25V 5,500 e.h.p. 4,100kW; D-25VF 6,500 e.h.p., 4,850kW. Kuznetsov NK-12M 12,000 e.h.p., 8,950kW; NK-12MV 14,795 e.h.p., ll,000kW. RoIIs-Royce/Snecma M57H 8,000 s.h.p., 5,970kW to 10,000 s.h.p., 7,460kW. Lycoming LTC4V-1 5,000 s.h.p., 3,730kW. LTC4V-4 10,000 s.h.p., 7,460kW. 2,500 s.h.p., 1,865kW—5,000 s.h.p., 3,730kW AS WITH THE high-power bracket, this medium-power sector is not a highly competitive one. The two leading contenders, the Rolls-Royce Dart turboprop and Allison Model 501/T56 turboprop each have separate and well established niches, as have the Ivchenko AI-20 and AI-24 turboprops. The Pratt & Whitney JFTD12/T73 turboshaft has only one application, and two mutually competitive turboshaft/ turboprop series of Lycoming and General Electric, the LTC4B/LTC4R/T55 and CT64/T64 have yet to gain a civil application. The Dart, possibly the best known and most diversely used turbine aero engine in the world, is well past its zenith but continues in production at a steady level, while also generating a significant spares business for R-R. With a power span of 1,480 e.h.p., l,104kW to 3,025 e.h.p. 2,256kW, the Dart has been ordered over the past two decades for close on 2,000 aircraft of 15 different types, including eleven commercial and executive designs. Over 6,000 Darts have been delivered for service with 300 operators in 60 countries, and have completed more than 60 million hours flying. These are unrivalled statistics. Production deliveries of civil Darts are still under way for
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