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Aviation glossary

Geared turbofan

Also: GTF, geared fan engine

Engines

Turbofan with a reduction gearbox between the fan and the turbine that drives it, so that each can turn at its own most efficient speed.

What it is

In a conventional turbofan the fan sits on the same shaft as the low-pressure turbine, so both turn at the same speed. That is a compromise: the fan wants to turn slowly to limit the speed of its blade tips, which would otherwise generate losses and noise, while the turbine is most efficient turning fast. An epicyclic gearbox between the two lets the fan grow larger and slower, and the turbine become more compact, with fewer stages.

The result is a higher bypass ratio, lower fuel burn and less noise. The best-known example is Pratt & Whitney's PW1000G family, which powers the Airbus A220, the Embraer E2 and part of the A320neo family, among others. The idea is not new in smaller engines: the Honeywell TFE731 on business jets and the Lycoming ALF502 on the BAe 146 already drove their fans through a gearbox.

On Vuelopedia

Airbus A220 Embraer E-Jet E2 Pratt & Whitney

Related terms

TurbofanJet engine in which a large front fan drives air around the core, producing most of the thrust with greater efficiency and less noise. FanLarge bladed rotor at the front of a turbofan that accelerates the incoming air and generates most of the engine's thrust. Bypass ratioRatio between the mass of air that flows around a turbofan's core through the outer duct and the mass that passes through the core to be burnt. TurbineSet of bladed wheels that extracts energy from the hot combustion gases to drive the engine's compressor, fan or propeller. Specific fuel consumptionAmount of fuel an engine burns for each unit of thrust or power it produces over a given time; the standard measure of engine efficiency.
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This page was last updated on October 9, 2026

APA

Vuelopedia. (2026, October 9). Geared turbofan. Retrieved October 16, 2026, from https://vuelopedia.org/en/glossary/geared-turbofan

MLA

“Geared turbofan.” Vuelopedia, Fundación Poderia, 9 Oct. 2026, vuelopedia.org/en/glossary/geared-turbofan. Accessed 16 Oct. 2026.

Chicago

Vuelopedia. “Geared turbofan.” Fundación Poderia. Last modified October 9, 2026. https://vuelopedia.org/en/glossary/geared-turbofan.

Harvard

Vuelopedia (2026) Geared turbofan. Available at: https://vuelopedia.org/en/glossary/geared-turbofan (Accessed: 16 October 2026).

BibTeX

@misc{vuelopedia_en_glossary_geared_turbofan,
  author       = {{Vuelopedia}},
  title        = {{Geared turbofan}},
  publisher    = {Fundación Poderia},
  year         = {2026},
  date         = {2026-10-09},
  url          = {https://vuelopedia.org/en/glossary/geared-turbofan},
  howpublished = {\url{https://vuelopedia.org/en/glossary/geared-turbofan}},
  urldate      = {2026-10-16},
  note         = {Accessed 2026-10-16}
}

Wikipedia

{{cite web |url=https://vuelopedia.org/en/glossary/geared-turbofan |title=Geared turbofan |website=Vuelopedia |publisher=Fundación Poderia |date=2026-10-09 |access-date=2026-10-16 |language=en}}

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