Kielce 2025-01-25
General Electric T-700, CT-7 engines.
The General Electric T700 is a turbine engine developed in the USA by General Electric and initially dedicated to helicopter propulsion. The prototype of the engine was launched in 1973. The engine was used as the main drive for helicopters and aircraft: Bell AH-1W Super Cobra, Bell AH-1Z Viper, Bell UH-1Y Venom, Boeing AH-64 Apache, CASA/IPTN CN-235, KAI KUH-1 Surion, Saab 340, Sikorsky UH-60 Black Hawk, Sikorsky SH-60 Seahawk. Over 20,000 units were produced. The General Electric T700 and CT7 are a family of turboshaft and turboprop engines, with a power of 1,100–2,200 kW.
History.
In 1967, General Electric began work on a new turboshaft engine demonstrator, designated the GE12. This was the company’s response to the US Army’s interest in a new generation military helicopter. The GE12 was designed by engineers Art Adamson and Art Adinolfi, from the GE concern. In 1967, both GE and Pratt & Whitney received contracts for parallel cooperation in the design, production and testing of new engines. At that time, the Sikorsky S-70 Black Hawk helicopter was developed, which used two GE T700 engines, which were a development of the GE12 design. The first ground tests of the T700 engine were carried out in 1973. Military certification was granted in 1976. Serial production of the T700 engines began in 1978. The T700-GE-700 engine design is based on; 5-stage axial compressor, 1-stage centrifugal compressor, annular combustion chamber with central fuel injection, 2-stage compressor turbine, 2-stage free turbine connected to a gearbox. A separator of solid particles, e.g. sand, is used at the engine inlet. The rated power of the T700-GE-700 engine is 1,210 kW.
Then the entire T700 engine family was developed, which, for example, was adapted to power marine helicopters, combat and commercial helicopters. T700 engines are also used in Italian commercial versions of the AgustaWestland EH101/AW101 helicopter and Italian versions of the NHIndustries NH90 helicopter. All of these machines are twin-engine, except for the three-engine EH101 helicopter.
The commercial version of the T700 is the CT7 engine. The main difference is the fuel used, which forced a change in the injection system. Turboprop versions were also developed for powering aircraft; the Swedish SAAB 340 passenger plane, the Indonesian-Spanish Airtech CN-235 transport plane and the Czech Let L-610G passenger plane. The basic CT7-5A turboprop engine has a power of 1,294 kW. In the 1980s, a larger turboprop engine was developed, which was designated T407/GLC38, with a power of 4,475 kW. At that time, electronic fuel injection systems were also introduced.
T-T Engine Data T700:
Length: 47 in. (1,200 mm) (T700-GE-700/701 series); 48.2 in. (1,220 mm) (T700/T6A). Diameter: 25 to 26 in. (640 to 660 mm) (T700/T6E). Dry Weight 400 lb (180 kg) (YT700-GE-700), 437 lb (198 kg) (T700-GE-700), 537 lb (244 kg) (T700/T6E).
Construction: Compressor: 6-stage – 5-stage axial, 1-stage centrifugal. Combustion Chambers: Annular. Turbine: 2-stage gas generator and 2-stage free turbine. Fuel Type: JP-4 or JP-5 (YT700-GE-700). Oil System: Self-contained, pressurized, recirculating, dry-type reservoir.
Maximum Power Output: YT700-GE-700: (1,145 kW), T700-GE-700: 1,210 kW, 700/T6E: 1,775 kW, YT706-GE-700: 1,967 kW.
Total Compression Ratio: 17:1. Specific Fuel Consumption: 0.433 lb/(hp⋅h) (263 g/kWh) (T700/T6E) to 0.465 lb/(hp⋅h) (283 g/kWh) (T700-GE-701A). Power-to-weight ratio: 3.84 shp/lb (6.31 kW/kg) (YT700-GE-700), 3.71 shp/lb (6.10 kW/kg) (T700-GE-700), 4.48 shp/lb (7.37 kW/kg) (T700/T6E).
CT7 engine for Poland.
On October 17, 2022, GE Aerospace announced that four AW101 helicopters and 32 AW149 helicopters ordered by Poland will be equipped with CT7 family engines, specifically, CT7-8E engines in the AW101 (three in each helicopter) and CT7-2E1 engines in the AW149 (two in each helicopter). The Polish Army reported that the CT7-2E1 engines best meet our needs in all aspects, such as: performance, maintenance costs, reliability and similarities to engines used in our other helicopters, such as; Black Hawk and AW101 (used by Italy), as well as in the future in AH-64 Apache helicopters. The choice of CT7 engines for the ordered helicopters was not obvious, because the AW101 helicopters were also manufactured with Rolls-Royce Turbomeca RTM322 engines, and the Safran Aneto-1K engine is also available for the AW149. According to data from the certificate granted by EASA (European Aviation Safety Agency) in 2020, the GE CT7-2E1 engine used in the AW149 is characterized by a take-off power of 1,480 kW and a maximum continuous power of 1,395 kW, and the GE CT7-8E engine used in the AW101 is characterized by a take-off power of 1,884 kW and a maximum continuous power of 1,522 kW. Poland will receive 64 CT7-2E1 engines, along with spare engines for 32 ordered AW149 helicopters. Deliveries of the contracted equipment began in 2023.
Written by Karol Placha Hetman