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Aviation History
1985
1985 - 1274.PDF
PROPULSION P&W pushes Tay competitor EAST HARTFORD ~ Pratt & Whitney still plans to proceed with development of the JT8D-400 turbofan for Boeing's 737-200 and a pro posed 100-seat derivative, the 737 Lite. Although Boeing has not yet decided whether to launch the 737 Lite, Pratt & Whitney says that certification of the 14,000-16,0001b-thrust JT8D- 400 is scheduled for mid-1987, making deliveries of the first aircraft possible in early 1988. This coincides with Boeing's plans. According to the engine manufacturer, the JT8D-400 will enable the existing 737-200 to meet the most stringent noise requirements planned by the US Federal Aviation Administration (FAA). In addition to a new fan and low-pressure turbine, the -400 will have a core/ bypass exhaust mixer nozzle to reduce noise. Compared with the simi larly sized JT8D-15A, an earlier model, the -400 will offer a 7 per cent lower specific fuel consumption, says P&W. Fan diameter will be increased 5in and the low- pressure turbine will incorpo rate technology developed for Pratt & Whitney's new PW2037 and PW4000 turbofans. The JT8D-400 is intended as a competitor to the Rolls- Royce Tay turbofan for the 737 Lite application. The 100-seat Lite is itself intended as a competitor to the Tay- powered Fokker 100. Several airlines are currently evalu ating Boeing's proposals. If key customer United Airlines was to place an order of sufficient size, Boeing could launch the new aircraft by June. The latest JT8D model to achieve FAA certification, in late March, is the -219 for the McDonnell Douglas MD-83. Compared with the JT8D- 200-powered MD-80, the For HiMAT read HiStol As part of a US Air Force-sponsored Stol exhaust nozzle programme, a windtunnel model of Rockwell's HiMAT highly manoeuvrable research vehicle has been configured with vectoring nozzles developed by Rolls-Royce. The 54in-span model represents a 12 per cent scale model of one of four single-engined Stol configurations evaluated, and has been used to check performance at transonic speeds. extended-range MD-83 has 5 per cent more take-off and climb thrust and 2 per cent lower specific fuel con sumption. Relative to the JT8D-200, the -219 incorporates a new high-pressure turbine, re designed low-pressure tur bine, and improved aerofoil aerodynamics. Take-off thrust of the JT8D-219 is 21,0001b and maximum thrust 21,7001b. GE runs R-R engine PEEBLES ~ The first Rolls-Royce RB.211-535E4 turbofan to arrive at General Electric under a co-operative pro gramme between the two companies has begun endur ance testing at GE's Peebles facility. GE plans to ship a CF6-80C2 turbofan to Rolls- Royce in August, also for endurance testing. The 535E4 will be subjected to more than 2,000 endurance cycles simulating airline ser vice to provide General Elec tric with experience in oper ating the British engine. This particular 535E4 has already accumulated 1,700 cycles during testing in the UK. Under the engine-sharing agreement signed in May 1984 GE has begun to manufacture components for the 535E4, and plans to begin shipping parts to Rolls-Royce in November. At the same time GE will begin receiving CF6- 80C2 components now being produced by Rolls-Royce. The agreement gives Rolls- Royce access to a 60,0001b- thrust-class turbofan to com plement its existing engine range—Tay, V.2500, 535, and 524—and gives GE access to a 40,0001b engine to slot between the CFM56 and CF6-80C2. 0 Air-India has become the first airline to select the GE CF6-80C2 to power the extended-range Airbus A310- 300. Delivery of the engines, rated at 53,5001b thrust for this application, will begin late in 1985. Air-India will receive the first two of six A310-300s on order in April 1986. The CF6-80C2 has already been ordered by Thai Airways International to power four A300-600s, for which certification flight- testing began in March, and by Thai Airways for two A310-200s. All-cast T700 tested LYNN An all-cast version of General Electric's T700 turboshaft engine, which replaces many fabricated parts with fewer castings, has logged more than 325hr endurance testing. By replacing parts pre viously machined from forg- ings with thin-walled castings GE expects to lower engine cost without adding weight or affecting performance. Costs of the cast components are expected to be approximately 25 per cent lower than those fabricated parts in the current T700. Engine parts which are cast rather than fabricated include the swirl frame, outer mid- frame incorporating dump diffuser, inner midframe in corporating diffuser, turbine case, exhaust frame, and squirrel cage bearing sup ports. Casting the inner mid- frame reduces parts count from 250 to 50, while the outer midframe, comprising 100 parts in the fabricated ver sion, is a one-piece casting in the all-cast T700. Allison shows improvement INDIANAPOLIS Power and fuel consumption improvements over the cur rent Allison 250-C20B turboshaft have been demon strated by the latest C20R engine during prototype test runs. The C20R generated 18 per cent more power with 3 per cent lower specific fuel consumption, says Allison. Retaining the proven gear box and turbine of the C20B, the latest C20R has a higher compression-ratio compressor with fewer stages. Through improved aerodynamics Alli son is able to achieve an 8:1 compression ratio with four axial and one centrifugal compressor stages. The C20B achieves its 7:1 compression ratio with two more axial compressor stages. Capable of producing 495 s.h.p. at sea level, the Model 250-C20R is flat-rated to 450 s.h.p. 42 FLIGHT International, 27 April 1985
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