Geared turbofans

The next big thing in aircraft propulsion is the geared turbofan which should begin to enter service early in the next decade on the new Mitsubishi Regional Jet and Bombardier C Series, but what is it? Flight International explain it well :

A conventional turbofan is divided into high and low pressure spools, each consisting of a compressor and turbine. The low-pressure spool drives the fan and provides most of the propulsive power. The fan works best at slower speeds, while the rest of the spool - the compressors and turbines - are more efficient running at high speeds.

A geared turbofan introduces a reduction gearbox (as you might have guessed) between the fan and the turbine so they both operate at optimum speed.


GTF ground test

Pratt & Whitney's GTF is currently in development and it is hoped to deliver fuel savings of between 10 and 10% as well as cutting noise. The GTF is still ground testing but already has impressed some potential customers and has gained the attention of many airlines around the world.