To my understanding, turbofan engines get the majority of their thrust from the fan in front of the engine, up to around 70-80% while the core flow generates around 20-30%.

Forward movement is achieved by utilizing Newtons 3rd law - by moving masses of air backwards and thereby moving the aircraft forward.

The thrust will first push the engine forward, and then the engine mounting, and then the wing and the aircraft as a whole - but how exactly is the load from the fast moving thrust air taken up by the engine internals?

As wings generate lift, they bend to a varying degree. Do the fan and engine internals, e.g compressor and turbine blades bend as well? I can imagine the fan taking up a tremendous amount of thrust load and wants to leave the engine and travel forward out the housing.

How much of this is true? Any input or suggested reading on this is highly appreciated!


The thrust is generated at the fan and compressor blades, as these are the components which push the air back. It is then carried through their attachment disks to the shafts and from there to what are called thrust bearings. A simple thrust bearing is a fixed flange against which the shaft pushes, but of course they are usually a lot more sophisticated. Thrust can also be generated by careful shaping of the core exhaust duct, but on a subsonic turbofan it can at best be only a small amount. The force is then transferred through the engine's structural framework to its mountings and thence to the airframe itself.

Yes, everything in the engine will deform a bit under load. Luckily the load paths tend to be short, but it still has to be made stiff and strong, with as you say the mounting carrying the full thrust. Extensive use of high-strength materials is made in the engine to keep deformation down to manageable levels. Varying amounts of thermal expansion of different parts also take place. These combined movements necessitate the designing-in of mechanical tolerances, to prevent the binding of moving parts or local build-up of mechanical stresses.


The rotating parts of the engine, including the fan, are supported by bearings which allow them to turn with a minimum of friction. Those bearings also transmit the lift force generated by the rotating fan blades to the casing of the engine, which we call the thrust of the fan.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.