Mailing List flyrotary@lancaironline.net Message #13718
From: Finn Lassen <finn.lassen@verizon.net>
Subject: Re: [FlyRotary] Re: exhaust design question
Date: Sun, 12 Dec 2004 11:10:52 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Those triangular pieces are foam - some sound absorbing material. Hard materials like metal is not likely to absorb sound, rather they're likely to reflect it.

Look at arcustic (sp?) ceiling pates, carpet, curtains. Then compare to a naked room with hardwood floors.

Having the muffler, expecially a thin walled one, inside the cowling, and the cowling cowered with some fireproof sound dampening material, would undoubtedly help.

Finn

rijakits wrote:

A wild idea/question: How is the sound emitted from something like a
silencer?
Remember any pics of sound proof chambers - like the car manufacturers have
to check source and dynamics of sound coming of their cars. These chambers
are all full of triangular foam (or so it seems) to eat up the sound, as not
to reflect anything and falsify the data.

Would it work to weld triangular shaped pieces on the OUTSIDE of a muffler?
.... or better has anyone any idea or tried that already?
I have no reason to believe that this works, but I think is worth a thought!
Any sound engineers on the list?

I remember in the old LP (music) times the very highend turntables would
come with an accessory: a heavy glassplate that was to be supported by
inverse ceramic cones or glasscones that in turn where supposed to be placed
on ceramic or glass again (point down). Supposedly to not absorb any
frequency from the floor/suroundings and to not loose any sound to the floor
either....

I am not enough of a music conoseur to ever have found a difference, but
that doesn't mean it didn't work:))

Any ideas?

Thomas J.

 


Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster