World’s largest aircraft engine ready for testing

Aircraft manufacturers’ quest for lower fuel consumption has always led to larger engines. And the trend seems to be continuing.

Rolls-Royce has now completed the technical specification of what will be the world’s largest aircraft engine – the Ultrafan turbofan engine.

The diameter of the fan that draws air into the engine is 3.54 meters. This pushed General Electric’s GE9X to second place, with a fan diameter of 3.41 meters. The GE9X is specially developed for the Boeing 777x It flew for the first time in 2018.

Bigger fan provides more air

A bigger fan means it can suck more air, which gives more efficiency. A bypass ratio of over 15:1 is noted, which is high in these environments. In normal cases, turbofan engines for large commercial aircraft typically have a bypass ratio of 10:1. The ratio indicates how much air passes through the core of the engine where the turbines and compressors are located.

Fuel consumption is said to be 25 percent lower than the first-generation Trent engine (however, it was already launched in the 1990s, so this is a slightly oddly chosen reference).

To design such a large engine, Rolls-Royce had to switch to making the fan blades mainly from a lightweight carbon fiber composite. Only the outer parts of the blades are made of titanium, which means that the weight can be significantly reduced. In the GE9X, a carbon fiber composite is also used for the fan blades.

Exchange introduced

Another design choice that Rolls-Royce describes as necessary for such a large fan is the introduction of gearing in the form of a planetary gear. This allows the larger fan to spin at a slower speed, while allowing the subsequent compressor and turbine stages to spin faster. In conventional turbofan engines, the fan and turbine are usually connected directly through a shaft.

Last year Rolls-Royce broke the world record The gearbox in a test facility was able to transmit 64 megawatts, equivalent to 87,000 horsepower.

The next step in development is to test the entire engine at Rolls-Royce’s brand new facility in Derby, England – first on the ground and then a flying test facility in the form of a Boeing 747. To run on renewable jet fuel.

It is not clear which aircraft the engine will power. It will be a while before it is commercialized. Rolls-Royce says it will be on planes built from the 2030s onwards.