X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.24] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3848373 for flyrotary@lancaironline.net; Sat, 12 Sep 2009 22:58:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.24; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 3so645857qwe.25 for ; Sat, 12 Sep 2009 19:57:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=a+929rT6+nWnqbT/AS/E8cdyl27Et0upp8v38v09fsY=; b=Gi3tohEeJlAmO/7tHHplyJ8eYs4SwJe7dyWHIhtmHsYBDkHelz9Ty1hGfx78Fw7ukR Ki+VB+pRIABtTP5lND4MMN6QV+4vTEDBnxDo4KhMRbSEz/A4deoWrAK2hKOJiLJUlQNf lq8DBgxFa91oRVu8EyMUum5zaPpbSqZNi+VOc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=lUsHmDi8FrFjbP/44zLOvUXjLL6BDuTt472ROOaaNQ/4HekvnrATV6stmsPDx6xCy8 IN2TSW8GnhNhPm+zHjIvlX80NwC6LRblzWlrydSPHwU31UXT/o09f20LljdG5mcS0BQR 7FfrmRrGeXVJF/t8tgzMwGqOhkzKA2KNTQ9nY= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.117.145 with SMTP id r17mr4122314qaq.7.1252806415422; Sat, 12 Sep 2009 18:46:55 -0700 (PDT) In-Reply-To: References: Date: Sat, 12 Sep 2009 21:46:55 -0400 X-Google-Sender-Auth: 4ec803fd9e464e62 Message-ID: <1b4b137c0909121846j3eda40edg472e14474d673303@mail.gmail.com> Subject: Re: [FlyRotary] Re: cockpit soundproofing From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=00c09f90f2e55d155104736bb908 --00c09f90f2e55d155104736bb908 Content-Type: text/plain; charset=ISO-8859-1 Amen on the 'air gap noise' in the cockpit. Didn't realize how much of that there was until one day I took my headset off while in cruise flight. The wind noise was easily the loudest thing in the cockpit. It was deafening even when I throttled the engine back to idle! A little bit of weather stripping around the canopy gaps made a noticeable difference. Tracy On Sat, Sep 12, 2009 at 8:59 PM, Charlie England wrote: > Agreed. The extension idea was to just extend the pipes so the ends are > behind the cockpit. I think that Tracy actually had something like that for > a while & mentioned that it made the cockpit quieter. > > I have no proof, but I suspect that turning the pipes down can, in some > situations, actually add noise & heat to the floorboards due to the induced > turbulence whipping the exhaust back against the floor & also causing > drumming on the floor. My Lyc powered RV-4 has downturned pipes, & the floor > is so hot I'm pretty sure I could cook pancakes on it. > > Mike, Since you've flown RV's for a while, you may already be aware of > this; a lot of the higher frequency noise can be minimized in the cockpit by > just sealing up all the air leaks into the cockpit. The 1st -4 that I owned > was painful, even with a Lyc. Sealing up the air leaks around the canopy > made it easily tolerable, even with passive headsets. > > FWIW, > > Charlie > > Mark Steitle wrote: > >> Charlie, >> You're correct, turning the pipe down does add drag, but so does hanging >> a big square suitcase shaped box under the fuse. It just depends on how >> badly you want to quiet things down. Mark >> >> >> On Sat, Sep 12, 2009 at 3:03 PM, Charlie England < >> ceengland@bellsouth.net > wrote: >> >> Mark Steitle wrote: >> >> Mike, >> My first line of defense against the noise is an ANR headset. >> That's a given. >> I purchased some black foam from ACS that I installed on the >> interior walls and floor. From what I've read a lot of the >> noise comes in through the firewall and windows. Not much you >> can do about the windows, but it seems that a generous amount >> of soundproofing on the firewall will help the most. Lastly, >> you can turn the exhaust down so that it is directed away from >> the occupants? Or, run it back behind the pax, and fly faster >> than the speed of sound so it can't catch up to you. Mark S. >> >> On Sat, Sep 12, 2009 at 10:15 AM, Mike Wills > > >> wrote: >> >> I asked a few days ago and got no replies. Since things are >> a bit >> slow on the list now I'll try again. Anyone have any >> recommendations for a decent soundproofing material that I >> can add >> to my firewall and floorboards to tame this racket? Maybe >> the rest >> of the world will have to deal with the noise, but at least >> I can >> try to make it a little more pleasant for me. >> Mike Wills >> RV-4 N144MW >> >> >> Running it back past the occupants can actually be effective. >> Turning it down adds drag. >> >> I've often wondered why no one has tried carrying the pipes down >> several inches below the fuselage before turning them aft, and >> installing streamline inserts aft of the downpipes & between the >> fuselage bottom & the horizontal run of pipe, to get smooth air >> between the fuselage & the now-parallel exhaust stream. >> >> Charlie >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > --00c09f90f2e55d155104736bb908 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Amen on the 'air gap noise' in the cockpit.=A0=A0 Didn't realiz= e how much of that there was until one day I took my headset off while in c= ruise flight.=A0 The wind noise was easily the loudest thing in the cockpit= . It was deafening even when I throttled the engine back to idle! =A0 A lit= tle bit of weather stripping around the canopy gaps made a noticeable diffe= rence.

Tracy

On Sat, Sep 12, 2009 at 8:59 PM= , Charlie England <ceengland@bellsouth.net> wrote:
Agreed. The extension idea was to just extend the pipes so the ends are beh= ind the cockpit. I think that Tracy actually had something like that for a = while & mentioned that it made the cockpit quieter.

I have no proof, but I suspect that turning the pipes down can, in some sit= uations, actually add noise & heat to the floorboards due to the induce= d turbulence whipping the exhaust back against the floor & also causing= drumming on the floor. My Lyc powered RV-4 has downturned pipes, & the= floor is so hot I'm pretty sure I could cook pancakes on it.

Mike, Since you've flown RV's for a while, you may already be aware= of this; a lot of the higher frequency noise can be minimized in the cockp= it by just sealing up all the air leaks into the cockpit. The 1st -4 that I= owned was painful, even with a Lyc. Sealing up the air leaks around the ca= nopy made it easily tolerable, even with passive headsets.

FWIW,

Charlie

Mark Steitle wrote:
Charlie,
=A0You're correct, turning the pipe down does add drag, but so does han= ging a big square suitcase shaped box under the fuse. =A0It just depends on= how badly you want to quiet things down. =A0Mark
=A0

=A0On Sat, Sep 12, 2009 at 3:03 PM, Charlie England <ceengland@bellsouth.net <m= ailto:ceenglan= d@bellsouth.net>> wrote:

=A0 =A0Mark Steitle wrote:

=A0 =A0 =A0 =A0Mike,
=A0 =A0 =A0 =A0 My first line of defense against the noise is an ANR heads= et.
=A0 =A0 =A0 =A0 That's a given.
=A0 =A0 =A0 =A0 I purchased some black foam from ACS that I installed on t= he
=A0 =A0 =A0 =A0interior walls and floor. =A0From what I've read a lot = of the
=A0 =A0 =A0 =A0noise comes in through the firewall and windows. =A0Not muc= h you
=A0 =A0 =A0 =A0can do about the windows, but it seems that a generous amou= nt
=A0 =A0 =A0 =A0of soundproofing on the firewall will help the most. =A0Las= tly,
=A0 =A0 =A0 =A0you can turn the exhaust down so that it is directed away f= rom
=A0 =A0 =A0 =A0the occupants? =A0Or, run it back behind the pax, and fly f= aster
=A0 =A0 =A0 =A0than the speed of sound so it can't catch up to you. = =A0Mark S.

=A0 =A0 =A0 =A0On Sat, Sep 12, 2009 at 10:15 AM, Mike Wills <rv-4mike@cox.net
=A0 =A0 =A0 =A0<mailto:rv-4mike@cox.net> <mailto:rv-4mike@cox.net
=A0 =A0 =A0 =A0<mailto:rv-4mike@cox.net>>> wrote:

=A0 =A0 =A0 =A0 =A0 I asked a few days ago and got no replies. Since thing= s are
=A0 =A0 =A0 =A0a bit
=A0 =A0 =A0 =A0 =A0 slow on the list now I'll try again. Anyone have a= ny
=A0 =A0 =A0 =A0 =A0 recommendations for a decent soundproofing material th= at I
=A0 =A0 =A0 =A0can add
=A0 =A0 =A0 =A0 =A0 to my firewall and floorboards to tame this racket? Ma= ybe
=A0 =A0 =A0 =A0the rest
=A0 =A0 =A0 =A0 =A0 of the world will have to deal with the noise, but at = least
=A0 =A0 =A0 =A0I can
=A0 =A0 =A0 =A0 =A0 try to make it a little more pleasant for me.
=A0 =A0 =A0 =A0 =A0 =A0 =A0 Mike Wills
=A0 =A0 =A0 =A0 =A0 RV-4 N144MW


=A0 =A0Running it back past the occupants can actually be effective.
=A0 =A0Turning it down adds drag.

=A0 =A0I've often wondered why no one has tried carrying the pipes dow= n
=A0 =A0several inches below the fuselage before turning them aft, and
=A0 =A0installing streamline inserts aft of the downpipes & between th= e
=A0 =A0fuselage bottom & the horizontal run of pipe, to get smooth air=
=A0 =A0between the fuselage & the now-parallel exhaust stream.

=A0 =A0Charlie

=A0 =A0--
=A0 =A0Homepage: =A0http://www.flyrotary.com/
=A0 =A0Archive and UnSub: =A0 =A0 =A0http://mail.lancaironli= ne.net:81/lists/flyrotary/List.html




--
Homepage: =A0http:/= /www.flyrotary.com/
Archive and UnSub: =A0 http://mail.lancaironline.net:81/lists= /flyrotary/List.html

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