|T700 / CT7|
|CT7/T700 being shown at the Paris Air Show 2007|
The General Electric T700 and CT7 are a family of turboshaft and turboprop engines in the 1,500-3,000 shp class.
Design and development[edit | edit source]
In 1967, General Electric began work on a new turboshaft engine demonstrator designated the "GE12" in response to US Army interest in a next-generation utility helicopter. The Army effort led, in the 1970s, to development of the Sikorsky S-70 Black Hawk, powered by twin GE "T700" turboshafts, the production descendant of the GE12.
The T700 was initially bench-tested in 1973, passed military qualification in 1976, and went into production in 1978. The initial "T700-GE-700" is an ungeared free-turbine turboshaft, with a five-stage axial / one-stage centrifugal mixed-flow compressor, featuring one-piece "blisk" axial stages, with the inlet guide vanes and first two stator stages variable; an annular combustion chamber with central fuel injection to improve combustion and reduce smoke; a two-stage compressor turbine; and a two-stage free power turbine with tip-shrouded blades. The engine is designed for high reliability, featuring an inlet particle separator designed to spin out dirt, sand, and dust. The T700-GE-700 is rated at 1,622 shp (1,210 kW) intermediate power.
The T700-GE-700 was followed by improved and uprated Army engine variants for the UH-60 Black Hawk and the AH-64 Apache helicopters, as well as marinized naval engine variants for the SH-60 Seahawk derivative of the Black Hawk, the SH-2G Seasprite, and the Bell AH-1W Supercobra. T700s are also used on Italian and commercial variants of the AgustaWestland EH101/AW101 helicopter, and Italian variants of the NHIndustries NH90 helicopter. These are all twin-engine machines, except for the three-engined EH101.
The commercial version of the T700 is the "CT7", with the engine used on the Bell 214ST (an enlarged version of the Huey), commercial Black Hawks, and the Sikorsky S-92 derivative of the Black Hawk, all of which are twin-engine helicopters.
The CT7 turboprop variants use the same core as the turboshaft variants, with a propeller gearbox fitted forward of the core. CT7 turboprops are used on variants of the Swedish SAAB 340 airliner, the Indonesian-Spanish Airtech CN-235 cargolifter, and the Czech Let L-610G airliner, all twin-turboprop aircraft. The baseline CT7-5A provides 1,735 shp (1,294 kW) on takeoff.
In the late 1980s, GE also proposed a much larger turboprop, the T407/GLC38, with a five-stage axial/one-stage centrifugal mixed-flow compressor; an annular combustor with 15 burners; a two-stage compressor turbine; a three-stage power turbine; and max takeoff power of 6,000 shp (4,475 kW).
The YT706 is based on the CT7-8A engine. Compared with the T700 currently powering H-60 helicopters, the YT706 has a larger compressor, hot section improvements and a full authority digital engine control. The YT706 provides up to 30 percent more power than the current T700-701C and will increase the hot-and-high mission capability of the MH-60M Black Hawk procured by the U.S. Army for its Special Operations applications.
Variants[edit | edit source]
T700: Military turboshaft engine.
- YT700: Prototype version.
- T700-700: Initial T700 variant. The improved T700-GE-701A, -701B, -701C,-701D versions have also been developed fro the original -700.
- T700-TEI701D: Licensed produced version of Tusaş Engine Industries of Turkey. Developed for use in the Sikorsky/Turkish Aerospace Industries T-70 Utility Helicopter.
CT7 turboshaft: Commercial version of T700.
- CT7-2A : Basic model
- CT7-2D : Higher flow compressor and surface coatings to improve resistance to wear and corrosion
- CT7-2D1 : Similar to the CT7-2D but uses a CT7-6 type hot section
CT7 turbprop: Turboprop version of CT7.
Applications[edit | edit source]
T700/CT7 turboshaft[edit | edit source]
- AgustaWestland AW101
- AgustaWestland AW149
- AgustaWestland AW189
- AgustaWestland CH-149 Cormorant
- Bell 214ST
- Bell 525
- Bell AH-1W SuperCobra
- Bell AH-1Z Viper
- Bell UH-1Y Venom
- Boeing AH-64 Apache
- KAI Surion
- Kaman SH-2G Super Seasprite
- Lockheed Martin VH-71 Kestrel
- Mitsubishi H-60
- NHIndustries NH90
- Piasecki X-49
- Sikorsky CH-148 Cyclone
- Sikorsky HH-60 Jayhawk
- Sikorsky HH-60 Pave Hawk
- Sikorsky SH-60 Seahawk
- Sikorsky UH-60 Black Hawk
- Sikorsky S-70
- Sikorsky S-92
- Sikorsky S-97
CT7 turboprop[edit | edit source]
Specifications (T700)[edit | edit source]
- General characteristics
- Type: Turboshaft
- Length: 47 in (T700-GE-700/701 series) to 48.2 in (T700/T6A)
- Diameter: 25 in / 26 in (T700/T6E)
- Dry weight: 400 lb (YT700-GE-700); 437 lb (T700-GE-700); 537 lb (T700/T6E)
- Compressor: 6 stage-5 stage axial, 1 stage centrifugal.
- Combustors: Annular
- Turbine: 2 stage gas generator and 2 stage power turbine
- Fuel type: JP-4 or JP-5 (YT700-GE-700)
- Oil system: self contained, pressurized, recirculating dry sump
- Maximum power output:
YT700-GE-700:1,536 shp (1,145 kW);
T700-GE-700: 1,622 shp (1,210 kW);
T700/T6E: 2,380 shp (1,775 kW);
YT706-GE-700: 2,638 shp (1,967 kW)
- Overall pressure ratio: 17x
- Specific fuel consumption: 0.433 (T700/T6E) to 0.465 (T700-GE-701A)
- Power-to-weight ratio: 3.84 shp/lb (YT700-GE-700); 3.71 shp/lb (T700-GE-700); 4.48 shp/lb (T700/T6E)
See also[edit | edit source]
- Advanced Affordable Turbine Engine, a program to develop a T700 replacement
References[edit | edit source]
- "GE YT706 Production Contract Awarded by US Army". GE Aviation. 2007-08-13. http://www.geae.com/aboutgeae/presscenter/military/military_20070813.html. Retrieved 2007-08-16.
- Govt Competitive Test UTTAS YUH-60A, USAAEFA Proj # 74-06-1
- "GE YT706 Power Specifications". GE Aviation. http://geae.com/engines/military/yt706/index.html. Retrieved 2011-06-02.
The initial version of this article was based on a public domain article from Greg Goebel's Vectorsite.
[edit | edit source]
|Wikimedia Commons has media related to General Electric T700.|
- General Electric T700/CT7 Engine Family page on GE Aviation site
- Jet Engines by Greg Goebel on faqs.org
- General Electric CT7 Cutaway by FlightGlobal.com
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