X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from omr-m10.mx.aol.com ([64.12.143.86] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6735455 for flyrotary@lancaironline.net; Sun, 16 Feb 2014 20:54:02 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.143.86; envelope-from=shipchief@aol.com Received: from mtaomg-mcd01.mx.aol.com (mtaomg-mcd01.mx.aol.com [172.26.223.207]) by omr-m10.mx.aol.com (Outbound Mail Relay) with ESMTP id 1EDFA7020C539 for ; Sun, 16 Feb 2014 20:53:28 -0500 (EST) Received: from core-dda001b.r1000.mail.aol.com (core-dda001.r1000.mail.aol.com [172.29.52.1]) by mtaomg-mcd01.mx.aol.com (OMAG/Core Interface) with ESMTP id D50D938000088 for ; Sun, 16 Feb 2014 20:53:27 -0500 (EST) References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Sound Level Testing In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: shipchief@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8D0F99A2F463B98_1080_63658_webmail-m290.sysops.aol.com" X-Mailer: AOL Webmail 38380-STANDARD Received: from 184.78.169.203 by webmail-m290.sysops.aol.com (64.12.152.48) with HTTP (WebMailUI); Sun, 16 Feb 2014 20:53:27 -0500 Message-Id: <8D0F99A2F3A54B3-1080-189D1@webmail-m290.sysops.aol.com> X-Originating-IP: [184.78.169.203] Date: Sun, 16 Feb 2014 20:53:27 -0500 (EST) x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1392602008; bh=RFf+fCdPkn2+Qp8zUKHafU6r8k+ZI3sYv3xC+B/sKyY=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=qGmTlRdEqVRxh3ADw11S2HDxUC0ViMgnEzYOQgSY7ojK1Gx4Dj/ENxeCjBaVn6aoQ 3D8HYY9OVESd5hq2lpbYHvS/BOOn4xymwEHmAjBBGITZ24/5TChDTsScTBQ8gY/Fx7 z5IfQwRCwrOjiWi2t4dGfChrp22U0qvB/b4IBvSA= x-aol-sid: 3039ac1adfcf53016b9769cf This is a multi-part message in MIME format. ----------MB_8D0F99A2F463B98_1080_63658_webmail-m290.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" Charlie; You are so correct! And I re-read that several times before I hit "send". 119.7 116.8 114.6=20 I'm using the first scale that the devise defaults to when started. 30-130 = DBa. I think it has a 80-130 scale, and I can select DBc too, so I'll do th= at. Sorry, but I'm glad you caught it and added the detail on A & C scale. Of course, those readings are averages, they were varying a bit and I had t= o pick a number. I hold it so the video cam can pick it up and I can review= it. -----Original Message----- From: Charlie England To: Rotary motors in aircraft Sent: Sun, Feb 16, 2014 5:39 pm Subject: [FlyRotary] Re: Sound Level Testing =20 =20 On 2/16/2014 4:09 PM, shipchief@aol.com wrote: =20 =20 =20 =20 =20 =20 I bought a Wensn 30-130 Decibel sound meter off = fleabay. I use it to record sound levels in front = of my face in flight. =20 I first tested my RV-8 after installing a turn down = tip, but was also experiencing severe exhaust = leaks from my turbo: 19.7 DBa=20 =20 After fixing the leak, I recorded 16.8 DBa =20 Then I squeezed the turn down tip to a flattened rectang= le opening, and replaced the lost area with 1/4" holes, = which I bent to face backwards with a Philips screwdrive= r. a Piccolo Pipe, as it's known. Kind of a cheese grate= r for sound waves. Next reading: 14.6 DBa =20 This is still to loud for my worn out ears, so I bought = an Aeroturbine 2525 muffler, as described on this forum.= I've been collecting 304 stainless pipe bend, ball join= ts clamps and hangers. I hope to get something cobbled t= ogether this weekend. =20 I have a 2" exhaust pipe from the turbo which discharges= aft. The pipe has 2 90 degree bends and exhausts in and= parallel to the exit air ramp on the bottom. I plan to = use the Ford type exhaust hangers with 3/8" rods. =20 =20 =20 =20 =20 I, too, am looking forward to your report on how well it works.=20 =20 Suggest checking what's going on with your dB readings, though. 16 d= B is quieter than a bedroom at night, & likely inaudible to those of us = who have been flying for a decade or two. Realistic levels expected in t= he cockpit of a homebuilt will be between 85 dB (pretty good, but still = loud) & 120 dB (loud rock concert levels and painful to most of us). =20 I'd also suggest using the C scale instead of the A scale. The A sca= le is very commonly used, but it presents a very distorted view of the a= ctual sound level. It radically filters the low end of the spectrum, and= to a lesser extent, the high frequencies, as well. It will mask the lev= el of your actual noise exposure, especially at the low end of the noise= spectrum. =20 Charlie =20 ----------MB_8D0F99A2F463B98_1080_63658_webmail-m290.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii"
Charlie;
You are so correct! And I re-read that several times before I hit "sen= d".
119.7
116.8
114.6
I'm using the first scale that the devise defaults to when started. 30= -130 DBa. I think it has a 80-130 scale, and I can select DBc too, so I'll = do that.
Sorry, but I'm glad you caught it and added the detail on A & C scale.
Of course, those readings are averages, they were varying a bit and I = had to pick a number. I hold it so the video cam can pick it up and I can r= eview it.
-----Original Message-----
From: Charlie England <ceengland7@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, Feb 16, 2014 5:39 pm
Subject: [FlyRotary] Re: Sound Level Testing

=20 =20 =20 =20
=20
On 2/16/2014 4:09 PM, shipchief@aol.com wrote:
=20
=20
=20
=20
I bought a Wensn 30-130 Decibel sound meter off fleabay. I use it to record sound levels in front of my face in flight.
=20
 I first tested my RV-8 after installing a turn down tip, but was also experiencing  severe exhaust leaks from my turbo: 19.7 DBa 
=20
After fixing the leak, I recorded 16.8 DBa
=20
Then I squeezed the turn down tip to a flattened rectangle opening, and replaced the lost area with 1/4" holes, which I bent to face backwards with a Philips screwdriver. a Piccolo Pipe, as it's known= . Kind of a cheese grater for sound waves. Next reading: 14.6 DBa
=20
This is still to loud for my worn out ears, so I bought an Aeroturbine 2525 muffler, as described on this forum. I've been collecting 304 stainless pipe bend, ball joints clamps and hangers. I hope to get something cobbled together this weekend.
=20
I, too, am looking forward to your report on how well it works.

Suggest checking what's going on with your dB readings, though. 16 dB is quieter than a bedroom at night, & likely inaudible to those of us who have been flying for a decade or two. Realistic levels expected in the cockpit of a homebuilt will be between 85 dB (pretty good, but still loud) & 120 dB (loud rock concert levels and painful to most of us).

I'd also suggest using the C scale instead of the A scale. The A scale is very commonly used, but it presents a very distorted view of the actual sound level. It radically filters the low end of the spectrum, and to a lesser extent, the high frequencies, as well. It will mask the level of your actual noise exposure, especially at the low end of the noise spectrum.

Charlie
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