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T56 / Model 501
Allison T56 turboprop for C-130 2007

The Allison T56 is a single shaft, modular design military turboprop with a 14-stage axial flow compressor driven by a four-stage turbine. It was originally developed by the Allison Engine Company for the Lockheed C-130 transport[1] entering production in 1954. It is now produced under Rolls-Royce which acquired Allison in 1995. The commercial version is designated 501-D. With an unusually long and numerous production run, over 18,000 engines have been produced since 1954, logging over 200 million flying hours.[2]

Design and development[]

Allison T56-A1 Turboprop Engine Cutaway

Allison T56-A1 turboprop engine cutaway, at the Smithsonian National Air and Space Museum

The T56 turboshaft evolved from Allison's previous T38 series.[3] It was first flown in the nose of a B-17 test-bed aircraft in 1954.[3] Originally fitted to the Lockheed C-130 Hercules, the T56 was also installed on the P-3 and E-2/C-2 aircraft, as well as civilian airliners such as the Lockheed Electra and Convair 580.[3] T56 development almost ended before it began when the T56-A-1 engine Allison delivered to Lockheed in May, 1953 produced only 3,000 hp, not the required 3,750 shp needed for the C-130. Further setbacks occurred in August 1953 when the engine under test only ran for 6 ½ hours before exploding on the test stand. A re-design of the engine ended in the same fate in September of the same year. After a second re-design, success was realized by the Allison team. Evolution of the T56 has been achieved through increase of internal pressure and temperature factors. The T56-A-14 installed on the P-3 Orion has a 4591 shp rating with a compression ratio of 9.25:1 while the T56-A-427 fitted to the E-2 Hawkeye has a 5250 shp rating and a 12:1 compression. In addition, the T56 produces approximately 750 lbs of thrust from its exhaust.[4]

A shipboard version, the 501K engine, is used to generate electrical power for all U.S. Navy cruisers and destroyers currently in commission.[2]

An engine enhancement program saving fuel and providing lower temperatures in the T56 engine was approved in 2013, and the US Air Force expects to save $2 billion and extend the C-130 fleet life.[5]

In the Lockheed Martin C-130J Super Hercules which first flew in 1996, the T56 is replaced by the Rolls-Royce AE 2100, which uses dual FADECs (Full Authority Digital Engine Control) to control the engines and propellers.[6] It drives new six-bladed scimitar propellers from Dowty Rotol.

Variants[]

501-D13
(Series I) Lockheed L-188 Electra and Convair CV-580 (Replacing P&W R-2800) starting December 1957
501-D13A
(Series I) Similar to -D13
501-D13D
(Series I) Similar to -D13
501-D13H
(Series I) Similar to -D13
501-D22
(Series II) Lockheed L-100 Hercules
501-D36A
(Series II) (non-type certified)
501-D22A
(Series III)
501-D22C
(Series III) similar to -D22A
501-D22G
(Series III) similar to -D22A
501-M62
Company designation for the T701-AD-700 turboshaft engine to power the Boeing-Vertol XCH-62 Heavy-lift helicopter
Allison T56 mobile test unit MCAS Futenma 1982

A T56 on a mobile test unit at MCAS Futenma, 1982

US Navy 081219-N-5142K-048 Bob Maiuvo works alongside Aviation Machinist Mate 2nd Class Tim Triest and Aviation Machinist Mate 2nd Class Marquette Beasley

Maintenance of a T56-A-16, 2009

T56-A-7
(Series I)
T56-A-8
(Series I)
T56-A-9
(Series I)
T56-A-9D
(Series I) Lockheed C-130A Hercules Starting December 1956 and on all Grumman E-2A Hawkeyes from 1960
T56-A-9E
(Series I) Similar to -A-9D
T56-A-10W
(Series I) with water injection
T56-A-7A
(Series II) Lockheed C-130B Hercules Starting May 1959
T56-A-7B
(Series II) Similar to -A-7A
T56-A-10WA
(Series II)
T56-A-14
(Series III) Lockheed/Kawasaki P-3/EP-3/WP-3/AP-3/CP-140 Aurora from August 1962
T56-A-15
(Series III) Lockheed C-130H Hercules from June 1974
T56-A-16
(Series III)
T56-A-425
(Series III) Grumman C-2A Greyhound from June 1974
T56-A-14+
(Series 3.5) Fuel efficiency and reliability upgrade, Lockheed WP-3D Orion from May 2015.
T56-A-15+
(Series 3.5)
T56-A-16+
(Series 3.5)
T56-A-425+
(Series 3.5) Northrop Grumman E-2 Hawkeye from August 2011
T56-A-427
(Series IV) Northrop Grumman E-2 Hawkeye upgrades from 1972
T56-A-427A
(Series IV) similar to the -A-427
T701-AD-700
(501-M62) Turbo-shaft engine for the Boeing-Vertol XCH-62 Heavy-lift helicopter.

Applications[]

Military[]

Civilian[]

Specifications (T56 Series IV)[]

Data from Rolls-Royce.[7]

General characteristics
  • Type: Turboprop
  • Length: 146.1 in (3,711 mm)
  • Diameter: 27 in (690 mm)
  • Dry weight: 1,940 lb (880 kg)
Components
  • Compressor: 14 stage axial flow
  • Combustors: 6 cylindrical flow-through
  • Turbine: 4 stage
  • Fuel type: JP8
Performance
  • Maximum power output: 4,350 shp (3,915 kW) limited to 4,100
  • Turbine inlet temperature: 860°C
  • Fuel consumption: 2,412 pounds per hour
  • Power-to-weight ratio: 2.75:1 (shp/lb)


See also[]

  • Allison T38
  • Allison T40
  • Bristol Proteus
  • Ivchenko AI-20
  • Lycoming T55
  • Napier Eland
  • Rolls-Royce Tyne

References[]

  1. Global Security T56
  2. 2.0 2.1 "Rolls Royce T56 Product Sheet". www.rolls-royce.com. http://www.rolls-royce.com/Images/t56_tcm92-6711.pdf.  Retrieved on 1 November 2012.
  3. 3.0 3.1 3.2 "Global Security T56publisher=www.globalsecurity.org". http://www.globalsecurity.org/military/systems/aircraft/systems/t56.htm. Retrieved on 1 November 2012.
  4. "The Rolls-Royce Allison T56 is fifty". New Zealand Aviation News, September, 2004. http://miravim.org/avimlibrary/Manuals/Powerplant%20Manuals/Aircraft%20Propellers/Other%20Manufacturers/Rolls-Royce%20Allison%20T56%20Turns%2050.pdf.  Retrieved on 2 November 2013
  5. "NOAA 'Hurricane Hunters' First To Get T56 Series 3.5 Engine Enhancement" Aero News, November 14, 2013. Accessed: December 1, 2013.
  6. "Rolls Royce AE-2100 Product Sheet". www.rolls-royce.com. http://www.rolls-royce.com/Images/AE2100_tcm92-6712.pdf.  Retrieved on 1 November 2012.
  7. Rolls, Royce . Training Manual . T56/501D Series III. Rolls-Royce, 2003. 8-1 To 8-24. Print.

External links[]

All or a portion of this article consists of text from Wikipedia, and is therefore Creative Commons Licensed under GFDL.
The original article can be found at Allison T56 and the edit history here.
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