MolaKule Q&A on Aircraft Structures VII Engines

[MolaKule]

New Engine/Nacelle Question:

On most aircraft, the turbofan engine is "setback" in the nacelle. I.e., from the front of the nacelle to the fan, there is a space.

Owing to the shape of the nacelle, explain why this position is preferred.

 

[barryh]

Could there be air spillage out the front if the fan was not set back in the nacelle.

 

[tbm5690]

New Engine/Nacelle Question:

On most aircraft, the turbofan engine is "setback" in the nacelle. I.e., from the front of the nacelle to the fan, there is a space.

Owing to the shape of the nacelle, explain why this position is preferred.

Obviously the only reason is to allow for cool pictures of pilots sitting/standing in the nacelle.

 

[barryh]

Another reason for the fan being set back in the nacelle might be noise reduction.

 

[MolaKule]

Another reason for the fan being set back in the nacelle might be noise reduction.

It does reduce fan noise to some extent.

Owing to the shape of the nacelle, explain why this position is preferred.

The general shape of the nacelle is one of a converging duct, but there is an additional factor in play. Since the 'area' of the inlet is larger than the fan's area, this represents a "ram" effect in flight, increasing air flow and pressure through both the nacelle and the core.

Remember, It comes down to four distinct parts that can be described with four verbs: suck, squeeze, bang and blow.'