Allison T56

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T56 / Model 501
Allison T56 turboprop for C-130 2007.JPEG
Type Turboprop
National origin United States
Manufacturer Allison Engine Company
Rolls-Royce plc
Major applications C-130 Hercules
C-2 Greyhound
E-2 Hawkeye
P-3 Orion

Lockheed Electra Allison Convair 580

Number built >18,000
Developed from Allison T38

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[edit]

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 of 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 third 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[edit]

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
A T56 on a mobile test unit at MCAS Futenma, 1982
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 III.V) Fuel efficiency and reliability upgrade
T56-A-15+
(Series III.V)
T56-A-16+
(Series III.V)
T56-A-425+
(Series III.V) 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[edit]

Military[edit]

Civilian[edit]

Specifications (T56 Series IV)[edit]

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[edit]

Related development
Comparable engines
Related lists

References[edit]

  1. ^ Global Security T56
  2. ^ a b "Rolls Royce T56 Product Sheet". www.rolls-royce.com.  Retrieved on 1 November 2012.
  3. ^ a b c "Global Security T56publisher=www.globalsecurity.org". Retrieved on 1 November 2012.
  4. ^ "The Rolls-Royce Allison T56 is fifty". New Zealand Aviation News, September, 2004.  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.  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[edit]