Specifications Model 250-C18 (T63-A-700) ĭata from The Instrumentation Design And Control of a T63-A-700 Gas Turbine Engine General characteristics Mitsubishi CT63 Licence production for Kawasaki-Hughes 500 / OH-6A helicopters. Ran on a Hughes YOH-6A Light Observation Helicopter in 1967. First regenerative engine to fully power a VTOL aircraft in flight. The -C20B is typical, with an overall pressure ratio of 7.2:1, at an airflow of 3.45 lb/s (1.8 kg/s), with a power output, at the shaft, of 420 hp (310 kW). combustion module (including twin compressed air transfer ducts) at the rearĮarlier versions have seven axial compressor stages mounted on the HP shaft to supercharge a relatively low-pressure-ratio centrifugal compressor.turbine module (including V-shaped exhaust ports).gearbox module (including accessory drives).compressor module, at the front of the engine.Also the unique reverse-flow design provides for ease of hot section maintenance. The exhaust stream then turns through 90 degrees to exit the engine in a radial direction through twin exhaust ducts, which form a V-shape seen in the front elevation.Īn important design feature of the Model 250 engine is its modular construction which greatly simplifies maintenance and repair activity. ![]() A coaxial stub shaft connects the power turbine to a compact reduction gearbox, located inboard, between the centrifugal compressor and the exhaust/power turbine system. The combustion products continue to expand through the two-stage power turbine which generates shaft horsepower for the aircraft. The combustion products expand axially forward through the two-stage (single-stage on early engines) high-pressure turbine section, which is connected to the compressor via the HP shaft. ( May 2022) ( Learn how and when to remove this template message)Īllison 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 ported rearwards via two transfer pipes, which go around the outside of the turbine system, before the air is turned through 180 degrees at entry to the combustor. Unsourced material may be challenged and removed. Please help improve this section by adding citations to reliable sources. 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. The Model 250 powers a large number of helicopters, small aircraft and even a motorcycle ( MTT Turbine Superbike). The Hughes OH-6 design, powered by the T63, was selected for the US Army LOH in May 1965. ![]() This version, rated at 250 hp, passed the Model Qualification Test in September 1962. A modified version of the engine (YT63-A-5) with the exhaust pointing upwards (to avoid grass fires) soon followed. ![]() The YT63-A-3 first flew in a variant of the Bell 47 helicopter in 1961. In 1960, the US Army settled for a rotary wing platform. These studies culminated in the testing of the first prototype engine, designated YT63-A-3, in April 1959. Design studies undertaken considered a wide range of possible mechanical configurations for the turboprop/turboshaft. At this stage the US Army was unsure whether to have a fixed- or rotary-wing aircraft, so Allison was instructed to consider both applications. In 1958, the Detroit Diesel Allison division of General Motors was chosen by the US Army to develop a new light turbine engine to power a "Light Observation Aircraft" (LOA), to replace the Cessna O-1A Bird Dog. The Model 250 has been produced by Rolls-Royce since it acquired Allison in 1995. 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.
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