Fuel efficiency is good for the environment, but it also saves airlines money. That doesn't mean the price of travel is falling. But it does mean a lot energy goes into advancing jet engine technology.
The British engine maker, Rolls-Royce, is proud of its new Trent XWB jet engine. They say it's the most fuel efficient engine in the world. It was designed specifically for the Airbus A350 passenger plane and uses light materials to reduce weight and increase fuel efficiency.
Engineers describe it with four words, saying it "sucks, squeezes, bangs, and blows."
The Trent XWB sucks in about 1.3 tonnes of air per second. The air is compressed, or "squeezed," and then in the combustion chamber, it is heated to about half the surface temperature of the sun. Finally, "bang" - and the engine blows the air back out, creating a thrust of 97,000lbs.
It was on show for the first time at the 2016 Hanover Fair.