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Comment by thePhytochemist | Hacker News Reader

Haha, nice timing that this appears after the "why are airplanes so hard to build?" article! Putting the engines to radiate sound upwards does make a lot of sense.

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I was intrigued, but acoustically it doesn’t make a lot of sense really…the thrust exhaust where all the fast moving air comes out, also happens to be where all the loud comes out too. Their renderings don’t look like the engines are far enough forward for the fuselage to provide any significant obstructions to the path of sound from the exhaust down to the ground.

I think that is what Nasa's X-59 plane that is doing to eliminate/minimize the sonic boom too. Pushing the boom upwards.

https://www.youtube.com/watch?v=2jAH-51feAA (Cleo Abram - NASA Is Bringing Supersonic Planes BACK)

We don't put engines on top because it makes maintenance alot harder.

Also safety. Uncontained engine failures shouldn’t ever happen (and maybe happen less as technology gets better), but when they do happen, it’s better for them to be under the wing away from the fuselage rather than right in the path of critical control systems.

Since this is a blended wing with no vertical stabilizer, it might be different, but it does still look like there are control surfaces right next to the engines..

> it’s better for them to be under the wing away from the fuselage rather than right in the path of critical control systems

but.... all the control surfaces are on the wing right next to that engine.

Ailerons and flaps are, but elevators and rudder that control the yaw and pitch of an aircraft are in the tail. See United Flight 232.

There's also the issue of ingesting the turbulent/detached boundary layer of the fuselage at high angles of attack, causing inlet distortions and the corresponding risk of compressor stall.

Link? Search can’t find it.

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