GarrettAiResearch ATF3

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The GarrettAiResearch ATF3 (military name GarrettAiResearch F104 ) is a turbofan engine from the US manufacturer Garrett AiResearch . It was the first three-shaft turbofan engine to be developed in the USA and is characterized by a multiple reversal of the gas flow in the engine. The bypass ratio is 2.88.

The development was carried out by AiResearch in Torrance . In 1966 the design and construction were completed. The first test runs with a demonstrator were carried out in 1968 and a supply contract for the ATF3 was concluded with the US Air Force. The first flight tests could take place in 1972 with pre-series turbines that delivered 18 kN of thrust.

In May 1976 the company announced that the HU-25 should be equipped with the ATF-3. The prerequisite for this was created with the approval for civil aviation in 1979.

In addition to the HU-25, the engine was also installed in the French Dassault Gardian and Dassault Falcon 200 aircraft, all from one series. In addition, it served as a drive in the Northrop Tacit Blue , and was for Ryan YQM-98A - drone program Compass Cope provided from.

The gas flow differs from the usual scheme in a turbofan engine. After flowing through the fan and medium pressure compressor, the combustion air is directed through eight pressure pipes into the engine tail, where it is deflected by 180 °, flows through a radial high-pressure stage from the inside to the outside and then reaches a combustion chamber with an S-shaped cross-section, which is both short and large Flame length results. The flow then changes direction twice in this combustion chamber by 180 ° each time, so that the flow through the turbine is opposite to the gas outlet direction.

The hot gas then passes through the axial turbines for the high-pressure compressor, fan and medium-pressure part one after the other. It is then deflected again by 180 °, exits approximately in the middle of the engine, where it mixes with the airflow from the fan to be expanded in a nozzle that extends to the rear. All auxiliary units are located in a large tail cone on the rear core engine.

A total of five versions of the engine were produced:

The XF104-GA-100 for the Ryan YQM-98A with 18 kN thrust, the ATF3-6-2C and -4C with a 36-blade fan and a gear housing made of aluminum for the HU-25, the ATF3-6A-3C with a 30-blade fan and an aluminum gearbox for the French Dassault Gardian and the ATF3-6A-4C, which corresponds to the 3C, but has a magnesium gearbox and was used for the Dassault Falcon 200.

The total number of engines delivered to customers is 227.

Technical data (ATF3-6)

  • Air flow: 73.5 kg / s
  • Pressure ratio: 21: 1 on the ground, 25: 1 at high altitude
  • Bypass ratio: 2.88: 1
  • Fan: single-stage, axial, titanium
  • MD compressors: five-stage, axial, titanium
  • HP compressors: single-stage, radial, titanium
  • HP turbine (for HP compressor): single-stage axial
  • MD turbine (for fan): three-stage axial
  • LP turbine (for MD compressor): two-stage axial
  • Length: 2316 mm
  • Diameter: 853 mm
  • Weight: 431 kg
  • Starting thrust: 22.46 kN

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