Re: [OM] OT: Noise levels in light aircraft, was More eruptions

[Sue Pearce]

> Hi Bill,
>
> I have never seen an effective muffler used on AC built in the US.
> Propeller tip noise is one of the big problems.  Most noise reduction 
> comes
> from using thicker windshields and side windows, and firewall and side 
> panel
> sound insulation, but all of these things add weight, which is not popular
> to a company selling carrying capacity.
>
The noise from prop tips is the sound of the tip going supersonic. It's a 
series of little sonic booms your entire trip.

Some of the light jet people have effectively used lead foil stuck to the 
inside of the fuselage skin. DeHaviland uses active noise cancellation in 
their twin turboprop commuter airliner, like a big Bose headset.

Bill Pearce 

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