Aircraft Engines - Turbo-Fan - Part 22

Published on: 2020-11-02
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Updated on: 2020-11-02
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Category: Articles
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Kraków 2017-01-14

Turbo-fan engine

General Electric CF6. 2014 year. Photo by Karol Placha Hetman
General Electric CF6. 2014 year. Photo by Karol Placha Hetman

General Electric CF6. 1971 year.

The General Electric CF6 commercial engine became a development of the General Electric TF39 engine. Its first launch took place in 1971. It was used as a drive for B747, B767, DC-10, A300, A310, A330 and others. The entire family of CF6 engines was created, from which subsequent generations of turbo-fan engines developed.

At the end of the 60's, General Electric Aviation offered civilian versions of the TF39 / CF6 engine for commercial aircraft. McDonnell Douglas for the DC-10 and Lockheed for the L-1011 showed interest. The latter eventually chose the competitive Rolls-Royce RB211 engine for their machines. The CF6-GE engine was also used in the B747 aircraft. Slightly later for the B767, A300, A310, A330 and B767, and the DC-10 development version of the MD-11. The CF6-GE-6 version was the first to enter serial production. The engine has made a major revolution in commercial transport. It allowed the construction of planes that would take up to 400 passengers on board and with a large range.

CF6 engines are operated according to technical condition. Therefore, from time to time the NTSB makes recommendations for specific inspection of certain engine components. This was the case in 2000 and 2010. The CF6 engine also noted black cards in its corner. The first was recorded in 1973, when the engine fan broke down. A greater tragedy occurred in 1989 when United Airlines flight 232 crashed (emergency landing in Sioux City, DC-10-10 plane).

General Electric CF6 engine structure: fan, 16 stage high pressure compressor, annular combustion chamber, 2 stage high pressure turbine, 5 stage low pressure turbine, hot flow outlet nozzle. The engine is equipped with a thrust reverser. The fan measures 86.4 in (2.1945 m) in diameter. The smaller diameter resulted from the need to accommodate the engine in airplanes with a low wing system. The fan has an air flow capacity of 590 kg / s. The total compression of the engine is 24.3: 1. The take-off thrust of the basic version of the CF6-GE-6 engine is 41,500 lfb (184.60 kN, 18,824.08 kG). Compared to the General Electric TF39 engine, the General Electric CF6 engine has some significant changes.

The next engine of the CF6 series was the CF6-GE-50 engine, which in fact was a development of the LM5000 industrial turbine, built on the basis of the CF6-GE-6. The new CF6-GE-50 engine was developed especially for the long-haul version of the DC-10-30 aircraft. The goal was to increase thrust to 51,000 lfb - 54,000 lfb (226.86 kN - 240.20 kN).

The idea of ​​increasing thrust was not that simple. It was not possible to increase the turbine inlet temperature indefinitely. In addition, the basic dimension of the fan diameter had to be kept so that the engine could fit in a typical CF06-GE-6 engine nacelle. General Electric Aviation decided on an expensive solution, the aim of which was to increase the compressor compression to 30: 1. This was achieved by removing the last two stages of the high pressure compressor and adding two additional stages of the low pressure compressor to the space thus created. As a result, the airflow through the fan increased to 660 kg / s, and the compression was 29.3: 1. (With the same fan diameter 86.4 in.) The engine achieved the assumed thrust of 51,000 lfb (226.86 kN). The CF6-GE-50 engine was launched in 1969. It was used in DC-10, B747, A300 and the Boeing YC-14 prototype. The CF6-GE-50 engine as a General Electric F103 went to USAF: KC-10 and Boeing E-4.

General Electric CF6-GE-50 engine data: 4.65 m (183 in) long, 2.67 m (105 in) diameter, total weight 4,067 kg - 4,104 kg (8,966 - 9,047 lb). The engine consists of a fan, 3-stage low pressure compressor, 14-stage high pressure compressor, annular combustion chamber, 2-stage high pressure turbine, 4-stage low pressure turbine. 52,500 lbf - 61,500 lbf (233.53 kN - 273.57 kN) thrust. Compressor compression 29.2: 1 - 31.1: 1. Thrust to weight ratio 5.6: 1 - 6: 1. The CF6-GE-50 engine with a 10% reduction in thrust was designated CF6-GE-45 and offered to aircraft for shorter distances.

The last sub-family of CF6 engines was the CF6-GE-80 series. The goal was to achieve a thrust of 48,000 lfb - 75,000 lfb (213.51 kN - 333.62 kN). They wanted to achieve this by increasing the compression.

The first in the subfamily was the CF6-GE-80A with a thrust of 48,000 lfb (213.51 kN). It was used for the B767 (1982), A310 (1983) drives. These were the first engines that enabled twin-engine airplanes to be able to fly ETOPS.

The word ETOPS is an acronym for Extended Operations, in free translation it means extended operation. ETOPS flights are those with over 60 minutes of flight to the nearest airport. In a word, it was about the ability to stay in the air as long as possible with one engine running. It made little difference over land. But at the ocean, yes. It was required that, with one engine running, the plane to the nearest airport should not fly longer than 60 minutes. It was impossible on the Atlantic Ocean. Therefore, the planes had 3 or 4 engines. The B767 was the first to cross the Atlantic Ocean with two CF6 engines without any problems. But the regulations did not allow it, because the plane would be flying in the ETOPS zone. That is why certificates began to be issued for twin-engine aircraft, which can last 120 or 180 minutes on a single engine. This provision allowed a twin-engine plane to fly across the Atlantic and Pacific Oceans.

The CF6-GE-80A engine is rated at 48,000 lfb (213.51 kN). Fan diameter unchanged (86.4 in). Air flow 651 kg / s. Compression 28: 1.

The CF6-GE-80C engine has a larger 93 in (2.3622 m) fan. The air flow is 790 kg / s. Compressor compression is 30.4: 1. Another stage was added to the high pressure compressor. Engine thrust is 59,000 lfb (262.45 kN). The engine as the F138-GE-100 is used to power the C-5M Super Galaxy aircraft. On the basis of the CF6-GE-80 engine, an industrial LM6000 turbine with a power of 40-56 MW, fueled by gas or light oil, was developed.

The CF6-GE-80E engine is the most powerful of the family. It has a thrust of 67,500 lfb - 72,000 lfb (300.25 kN - 320.27).

CF6-GE-50 engine data: 4.65 m (183 in) long, 2.67 m (105 in) diameter, total weight 4,067 kg - 4,104 kg (8,966 - 9,047 lb). The engine consists of a fan, 3-stage low pressure compressor, 14-stage high pressure compressor, annular combustion chamber, 2-stage high pressure turbine, 4-stage low pressure turbine. 52,500 lbf - 61,500 lbf (233.53 kN - 273.57 kN) thrust. Compressor compression 29.2: 1 - 31.1: 1. Thrust to weight ratio 5.6: 1 - 6: 1.

Written by Karol Placha Hetman