Will we be in for quieter plane rides?

The first jet engine, the turbojet, made by British engineer Frank Whittle, worked something like this. The thrust came from the air that was pushed into the front of the engine. Then, the air travelled into the compressor where it was squeezed, mixed with fuel, and ignited.  This causes the air, now very hot, to shoot out of the back of the engine, causing thrust.(The compressor was turned by a turbine that used exhaust gases to power itself.) But, these engines had a problem. They were not very fuel efficient and were very loud.

Next, came the turbofan engine, the engines that we use today. These engines worked similar to the turbojet engines. A fan, powered by the turbine, directed some air to move around the compressor instead of through it. Even though this air is not moving as fast as the exhaust gases, the sheer volume of it gives it more thrust than the turbojet. This made the engine more fuel efficient and quieter. Some of the latest and biggest turbofans engine fans are so big that they have a bypass ratio of 9:1. To explain this, we have to get into  little math. Let's say that we have ten parts of air. The 9:1 ratio means that only 1 part of the air is going inside the compressor while the other 9 parts are going around. This is much more efficient and provides a lot more thrust. These fans are getting bigger and bigger, but there is  a limit to which they can grow. As these fans get bigger, they also get faster and some fans are getting close to the speed of sound. If these fans reach the speed of sound, they will produce shock waves that cause dangerous vibrations. To slow down the fans but still keep the turbine running at an optimal speed, we need gearboxes. This is where the Purepower by Pratt and Whitney that is a geared turbofan engine comes in.

The fan will have a gearbox behind it and the engine will be bigger

Geared turbofans have been used in small jets for quite a few years. The reason they haven't been used in bigger jets is that since the engine is so big, the forces acting on the gearbox will be so high that it will break. Pratt and Whitney has been working on this problem for more than 15 years and spent more than $10 billion. But, all this work has paid off. Pratt and Whitney have created the new engine which is called the Purepower. They have a strong gearbox made out of nickel based alloys. This engine has a bypass ratio of 12:1 and is quieter and more fuel efficient. Even though this engine is going to be used by many planes, it has a few drawbacks. The engine will take quite a while to cool down. This may cause delays and in busy airports, take away a plane's take off shot.



It is too early to say whether the Purepower will be a success or not, but one thing is for sure. it will revolutionize the process of  engine manufacturing.