X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp105.sbc.mail.mud.yahoo.com ([68.142.198.204] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with SMTP id 3848041 for flyrotary@lancaironline.net; Sat, 12 Sep 2009 16:03:56 -0400 Received-SPF: neutral receiver=logan.com; client-ip=68.142.198.204; envelope-from=ceengland@bellsouth.net Received: (qmail 7864 invoked from network); 12 Sep 2009 20:03:20 -0000 Received: from unknown (HELO ?192.168.10.7?) (ceengland@70.152.72.25 with plain) by smtp105.sbc.mail.mud.yahoo.com with SMTP; 12 Sep 2009 20:03:19 -0000 X-YMail-OSG: gcArvMQVM1lf4NpUxcLo7oxdTFfw6VMLcg7aHA5me3LcmqfWO6IChPa3SSx1svqCwaOJDhgdN0jRlm4UIDs3QmYVfRTArZysUHL2kCbXo01BV_Y3P4R2uWB0dAf7Eft2BwvfejxSl4n5Eo79NaR64PfU6ZmSMk6f5GqD3VJ8KNpQUeg8mUdoWSx9pwJdyhTGvPaT1WAN49LQ3g3zbZhdwOcLJWoWzzu7Cylg6Z_TkCps7Tdc4zMtSJhBj1riIDtZwCdnfwCzIv3U9nKNlqo8gPuSW6Ns92gn0LhyB24uExPO X-Yahoo-Newman-Property: ymail-3 Message-ID: <4AABFE87.3010307@bellsouth.net> Date: Sat, 12 Sep 2009 15:03:19 -0500 From: Charlie England User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: cockpit soundproofing References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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