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Allison Model 250
The Allison Model 250 (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.
Contents
Design and development
Allison adopted a trombone-style 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 2-stage HP turbine, which is connected, via the HP shaft, to the compression system, before expanding through the 2-stage power turbine; the exhaust gases then turn though 90 degrees to exit the engine in a radial direction; a stub shaft connects the power turbine to a compact reduction gearbox, located inboard, between the centrifugal compressor and the exhaust/power turbine system.
One of the latest versions of the Model 250 is the -C40, which has a hi-tech centrifugal compressor pulling a pressure ratio of 9.2:1, at an airflow 6.1 lb/s (2.8 kg/s), and developing 715 shp (533 kW).
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, pulling an overall pressure ratio of 8.0:1, at an airflow of 4.0 lb/s (1.8 kg/s), with a power output of 450 shp (336 kW).
The Model 250 propels a large number of helicopters and small aircraft.[1] As a result, nearly 30,000 Model 250 engines have been produced. Of these, approximately 16,000 remain in service. The Model 250 is one of the highest-selling engines made by Rolls-Royce.
Variants
- 250-C18
- 250-C18A
- 250-C20
- 250-C20B
- 250-C20F
- 250-C20J
- 250-C20R
- 250-C20R/1
- 250-C20R/2
- 250-C20R/4
- 250-C20S
- 250-C20W
- 250-C22B
- 250-C28
- 250-C28B
- 250-C28C
- 250-C30
- 250-C30G
- 250-C30G/2
- 250-C30M
- 250-C30P
- 250-C30R
- 250-C30R/3
- 250-C30R/3M
- 250-C30S
- 250-C30U
- 250-C34
- 250-C40B
- 250-C47B
- 250-C47M
- 250-B15
- 250-B15A
- 250-B15C
- 250-B17
- 250-B17B
- 250-B17C
- 250-B17D
- 250-B17F
- 250-B17F/1
- 250-B17F/2
- T63A-5
- T63A-5A
- T63A-700
- T63A-720
- T703AD-700
Applications
- Agusta A109A
- Bell 206B/L/LT
- Bell 407
- Bell 230
- Bell 430
- Bell OH-58 Kiowa
- Cicaré CH-14
- Enstrom 480
- Eurocopter AS355F
- Extra EA-500
- Hughes OH-6 Cayuse
- MBB Bo 105
- MD Helicopters MD 500
- MD Helicopters MD 600
- MD 500 Defender
- MH-6 Little Bird
- MTT Turbine SUPERBIKE
- Schweizer 330, 330SP
- Schweizer S-333
- Sikorsky S-76
Template:Multicol-end
See also
References
External links
Template:Allison aeroengines Template:RR aeroengines Template:USAF gas turbine engines
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| This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Allison Model 250". |
