Allison Model 250




































Model 250 / T63

Allison (MTU) 250 C20B.jpg

MTU-built Allison 250-C20B
Type

Turboshaft

National origin

United States
Manufacturer

Allison Engine Company
Rolls-Royce plc

Major applications

Bell 206
MD Helicopters MD 500
MBB Bo 105
Sikorsky S-76

Number built
>30,000

Program cost
$6.4 million (1958)[1] (equivalent to $54,300,000 in 2017)

Unit cost
-C20B : $323,400 (2012)
-C30R/3 : $265,600 (2012)[2]

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.




Contents






  • 1 Design and development


  • 2 Variants


  • 3 Applications


  • 4 Specifications (T63-A-5)


    • 4.1 General characteristics


    • 4.2 Components


    • 4.3 Performance




  • 5 See also


  • 6 References


  • 7 External links





Design and development


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. At this stage the US Army were unsure whether to have a fixed- or rotary-wing aircraft, so Allison was instructed to consider both applications. Design studies undertaken considered a wide range of possible mechanical configurations for the turboprop/turboshaft. These studies culminated in the testing of the first prototype engine, designated YT63-A-3, in April 1959.[3] In 1960 the US Army settled for a rotary wing platform. The YT63-A-3 first flew in a variant of the Bell 47 helicopter in 1961. A modified version of the engine (YT63-A-5) with the exhaust pointing upwards (to avoid grass fires) soon followed. This version, rated at 250 hp, passed the Model Qualification Test in September 1962. Thus was born the Model 250. Incidentally, the Hughes OH-6 design was selected for the US Army LOH platform in May 1965,


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 (single-stage on early engines) high-pressure turbine section, which is connected to the compressor via the HP shaft. The combustion products continue to expand through the two-stage power turbine which generates shaft horsepower for the aircraft. 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 exhaust stream then turn through 90 degrees to exit the engine in a radial direction through twin exhaust ducts, which form a V-shape in elevation. An important design feature of the Model 250 engine is its modular construction which greatly simplifies maintenance and repair activity. Also the unique reverse-flow design provides for ease of hot section maintenance.


Earlier versions have 7 axial compressor stages mounted on the HP shaft to supercharge a relatively low-pressure-ratio centrifugal compressor. 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).


One of the latest versions of the Model 250 is the -C40, which has only a centrifugal compressor producing a pressure ratio of 9.2:1, at an airflow of 6.1 lb/s (2.8 kg/s), and develops, at the shaft, 715 hp (533 kW).


The Model 250 powers a large number of helicopters, small aircraft and even a motorcycle (MTT Turbine Superbike).[4] 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.



Variants




250-B15

250-B15A

250-B15C

250-B15G

250-B17

250-B17B

250-B17C

250-B17D

250-B17Fg

250-B17F/1

250-B17F/2

250-C10D

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-C47E[5]

250-C47M

T63-A-5

T63-A-5A

T63-A-700

T63-A-720

T703-AD-700

Soloy Turbine-Pac

Typically 2x 250-C20S driving a single propeller via a combining gearbox, able to operate individually.




Applications


Fixed-wing



  • Aermacchi M-290 RediGO

  • BAE Systems Mantis


  • Beechcraft Bonanza {Prop-jet conversions}

  • Britten-Norman BN-2T Turbine Islander

  • Extra EA-500

  • Fuji T-5

  • Fuji T-7

  • GAF Nomad

  • Gippsland GA10

  • Grob G 120TP

  • Partenavia AP.68TP variants - Spartacus & Viator

  • RFB Fantrainer

  • SIAI-Marchetti SF.260TP

  • SIAI-Marchetti SM.1019

  • Soloy Cessna 206 turbine conversion


  • Cessna P210 Silver Eagle O&N Aircraft Modifications - onaircraft.com



Rotary-wing



  • Agusta A109A


  • Bell 206B/L/LT

  • Bell 407


  • Bell 222SP

  • Bell 230

  • Bell 430

  • Bell OH-58 Kiowa

  • Bell YOH-4

  • Boeing AH-6

  • Cicaré CH-14

  • Enstrom 480


  • Eurocopter AS355F

  • Fairchild Hiller FH-1100

  • HESA Shahed 285

  • Hughes OH-6 Cayuse

  • MBB Bo 105

  • MD Helicopters MD 500

  • MD Helicopters MD 600

  • MD Helicopters MH-6 Little Bird

  • Northrop Grumman MQ-8 Fire Scout

  • PZL Kania

  • PZL SW-4

  • Schweizer 330/330SP

  • Schweizer S-333

  • Sikorsky S-76

  • Kamov Ka-226



Other applications



  • Loral GZ-22, non-rigid airship


  • MTT Turbine Superbike, motorcycle



Specifications (T63-A-5)


Data from Jane's All the World's Aircraft 1962-63.[6]


General characteristics




  • Type: Turboshaft


  • Length: 40.5 in (1,029 mm)


  • Diameter: 22.5 in (572 mm)


  • Dry weight: 136 lb (62 kg) dry


Components




  • Compressor: 6-stage axial + 1-stage centrifugal compressors


  • Combustors: Single can combustion chamber


  • Turbine: 2-stage axial gas generator power turbine + 2-stage axial free-power output turbine


  • Fuel type: JP-4 aviation kerosene (alternatively JP-1 or JP-5)


  • Oil system: pressure spray/splash, dry sump


Performance




  • Maximum power output: 250 hp (190 kW) for take-off, sea level 59 °F (15 °C)


  • Overall pressure ratio: 6.2:1


  • Air mass flow: 3 lb (1 kg)/s


  • Turbine inlet temperature: 1,805 °F (985 °C)


  • Specific fuel consumption: 0.77 lb/hp·h (0.468 kg/kW·h) at 90% power cruise rating


  • Power-to-weight ratio: 1.838 hp/lb (3.022 kW/kg)




























































































































Model
Weight (kg)
Air flow rate (kg/s)
Pressure
ratio
Take-off power (WPS)
Continuous power (WPS)
Height (mm)
Width (mm)
Length (mm)
C20B/F/J
73
1.230
6.2:1
420
370
571
483
986
C20R
78
1.733
7.9:1
450
380
589
528
986
B17D
90
1.624
7.2:1
420
370



B17F
93
1.733
7.9:1
450
380



C30M
113
2.54
8.6:1
650
540
638
555
1041
C30S
114
2.54
8.6:1
650
501
638
555
1041
C30P
114
2.54
8.6:1
650
501
638
555
1041
C40B
127
2.77
9.2:1
715
613
638
555
1040
C47B/M
124
2.77
9.2:1
650
600
638
555
1040
C47E[7]
133

9.2:1
700

630
630
1091


See also



  • Rolls-Royce RR300

  • Rolls-Royce RR500



References





  1. ^ "The Little Engine That Did". Vertical Mag. May 20, 2014..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""""'""'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}


  2. ^ "Rolls-Royce M250 Turboshaft Engine". AeroWeb. June 15, 2012.


  3. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2016-10-04. Retrieved 2016-03-14.CS1 maint: Archived copy as title (link)


  4. ^ "Archived copy". Archived from the original on 2006-08-24. Retrieved 2016-11-09.CS1 maint: Archived copy as title (link)


  5. ^ "Press releases". www.rolls-royce.com. Retrieved 1 June 2018.


  6. ^ Taylor, John W.R. FRHistS. ARAeS (1962). Jane's All the World's Aircraft 1962-63. London: Sampson, Low, Marston & Co Ltd.


  7. ^ "M250-C47E Turboshaft Specification" (PDF). Rolls-Royce. Retrieved 14 June 2016.




External links







  • Rolls-Royce M250 Official page

  • Video of running model











Popular posts from this blog

Florida Star v. B. J. F.

Danny Elfman

Lugert, Oklahoma