Noise Shielding by Rear-Mounted Engines on Aircraft

[physixlover]

How is the noise sheilding provided by the fuselage when the engines are mounted at the rear end of the aircraft ? for example-SAX 40

 

[boneh3ad]

That plane isn't designed to make the cabin an ultra-quiet design, it is designed to make the plane quiet to an observer on the ground.

 

[physixlover]

That plane isn't designed to make the cabin an ultra-quiet design, it is designed to make the plane quiet to an observer on the ground.

may be yes, but I need an explanation of how the noise is reduced when the engines are at the rear end

 

[JaredJames]

You need an explanation? Is this schoolwork?

Have you considered the difference between wing mounted engines and tail mounted? Have you looked up the noise associated with both?

 

[boneh3ad]

Being at the rear end isn't going to really do anything when it comes to noise. It has more to do with the design of the engines and the fact that they are largely above the body of the plane, so the body itself will block out some of the noise. I suggest googling the SAX-40 to learn more about the specifics. Google is your friend.

 

[JaredJames]

The location of the engines does play a part in how much noise there is.

Noise levels at different parts of the aircraft will vary depending on engine location.

 

[boneh3ad]

The location of the engines does play a part in how much noise there is.

Noise levels at different parts of the aircraft will vary depending on engine location.

But again, the SAX-40 is not designed with cabin noise in mind, it is designed with external noise pollution in mind. Rear engines have repercussions when it comes to cabin noise, so I think it is fairly plain to see that the folks at MIT and Cambridge who came up with the SAX-40 didn't have cabin noise in mind when designing it. The rear, above-the-body position has a marked advantage when it comes to ground noise.

It has a lot of the same design concepts as those behind the Boeing X-48, only it takes thing a step further by integrating said engines into the fuselage a la the B-2.

 

[JaredJames]

Blimey, thought the SAX-40 was a real aircraft (had an image of an old liner along the lines of the 717). Just Googled it and it's a concept aircraft.

Yeah, in the case of this design, if you imagine the sound waves coming off the engines they can travel upwards freely but not so well downwards. That's about as simply as it can be put.