Silent Aircraft Initiative

[Argos]

I thought some of the members might like to discuss (and contribute to) this topic.

http://www.cambridge-mit.org/research/sai

The Cambridge-MIT Institute's 'Silent' Aircraft Initiative was launched in November 2003 with a bold aim: to discover ways to reduce aircraft noise dramatically, to the point where it would be virtually unnoticeable to people outside the airport perimeter.

[John Kierein]

One of the major problems with the UAVs that the military use (especially the Army) is the noise signature. They are too noisy.

[genebujold]

While they're indeed noisy while taking off and landing, when they arrive at their operational altitude, they're virtually silent to anyone on the ground.

[Demigrog]

I'm all for quieter planes; it'd probably double my property value! :wink: I live under the approach path for the main runway at our local airport; I can all too often identify planes by their engine noise.

[PatKelley]

High capacity neutral buoyancy airships - like Lockheed-Martin's "Skunk Works" "Aerocraft" concept.
Yes, now six years on the drawing board, but a worthwhile concept: crashes would occur at relatively low speeds, runways could be shorter, and sound would, or could, be drastically reduced.

Travel times would increase, but... for the added safety, I'd take an Aerocraft over an airplane...

[John Kierein]

While they're indeed noisy while taking off and landing, when they arrive at their operational altitude, they're virtually silent to anyone on the ground.

But that's the problem, they give away their launch location and put the soldiers in jeopardy.

[Argos]

I´ve always liked the lifting body concept like the one in the picture. I also like using the undercarriage to generate useful, steady, drag. At first glance I thought that noise redux would be achieved by combining new materials and new ideas on aerodynamics. But now I see that they rely a great deal on the positioning of the engines to accomplish that. They isolate (hide) the engines up on the fuselage. A rather low-tech acoustic trick.