|
The Allison Model 250, now known as the Rolls-Royce M250, (US military designations T63 and T703) is a highly successful turboshaft engine family, originally developed by the Allison Engine Company in the early 1960s. The Model 250 has been produced by Rolls-Royce since it acquired Allison in 1995. ==Design and development== Allison adopted a reverse airflow engine configuration for the Model 250: although air enters the intake/compression system in the conventional fashion, the compressed air leaving the centrifugal compressor diffuser is ducted rearwards around the turbine system, before being turned through 180 degrees at entry to the combustor. The combustion products expand through the two stage gas generator turbine section, which is connected to the compressor via the HP turbine shafting. The combustion products continue to expand through the two stage power turbine which generates shaft horsepower for the aircraft. A stub shaft connects the power turbine to a compact reduction gearbox, located inboard, between the centrifugal compressor and the exhaust/power turbine system. The exhaust gases then turn through 90 degrees to exit the engine in a radial direction. One of the latest versions of the Model 250 is the -C40, which has a centrifugal compressor producing a pressure ratio of 9.2:1, at an airflow of 6.1 lb/s (2.8 kg/s), and developing, at the shaft, . Some of the earlier versions have axial compressor stages mounted on the HP shaft to supercharge a relatively low pressure ratio centrifugal compressor. The -C20R is typical, with an overall pressure ratio of 8.0:1, at an airflow of 4.0 lb/s (1.8 kg/s), with a power output, at the shaft, of . The Model 250 powers a large number of helicopters, small aircraft and even a motorcycle (MTT Turbine Superbike).〔http://www.atlasaviation.com/powerplant/aircraftapp.htm〕 As a result, nearly 30,000 Model 250 engines have been produced, of which approximately 16,000 remain in service, making the Model 250 one of the highest-selling engines made by Rolls-Royce. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Allison Model 250」の詳細全文を読む スポンサード リンク
|