X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from omr-d09.mx.aol.com ([205.188.108.133] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6744221 for flyrotary@lancaironline.net; Fri, 21 Feb 2014 23:55:18 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.108.133; envelope-from=shipchief@aol.com Received: from mtaomg-mca01.mx.aol.com (mtaomg-mca01.mx.aol.com [172.26.221.79]) by omr-d09.mx.aol.com (Outbound Mail Relay) with ESMTP id EE70D700000BE for ; Fri, 21 Feb 2014 23:54:44 -0500 (EST) Received: from core-ddb002b.r1000.mail.aol.com (core-ddb002.r1000.mail.aol.com [172.29.52.69]) by mtaomg-mca01.mx.aol.com (OMAG/Core Interface) with ESMTP id C97B538000081 for ; Fri, 21 Feb 2014 23:54:44 -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_8D0FDA156BA37DA_27B0_32E18_webmail-m151.sysops.aol.com" X-Mailer: AOL Webmail 38394-STANDARD Received: from 174.61.189.169 by webmail-m151.sysops.aol.com (64.12.101.140) with HTTP (WebMailUI); Fri, 21 Feb 2014 23:54:44 -0500 Message-Id: <8D0FDA156B0B256-27B0-D311@webmail-m151.sysops.aol.com> X-Originating-IP: [174.61.189.169] Date: Fri, 21 Feb 2014 23:54:44 -0500 (EST) x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1393044884; bh=HwbSkECRGQ7G+dMuVaimRORpnbN+6fyR0IYVAZYqy0M=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=yFxF9JlbevcQezXyR3GFzsq4ZNKhcbsYUq+b0q+n3jyOF3F7Q5HhFbTZjN70XxS0L geH6Ly1lZGIdicAw4qIVuOd7DCXx97VwX3u5aHe1rv8yYpea+gTIEH7r9TDLPeerPH 24wZUpd0PYzjspjNELt7Et5uCcT6SGrhOdxwR7u0= x-aol-sid: 3039ac1add4f53082d940fec This is a multi-part message in MIME format. ----------MB_8D0FDA156BA37DA_27B0_32E18_webmail-m151.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" Today I assembled enough bits to try out the Aero-turbine 2525 muffler. I didn't like the way the ball joints & pipes were fitting, so I reconfigur= ed that after the test, but I did run it in front of the hangar for a few m= inutes, and it is now much quieter. In fact, it seems quieter without my he= adset on that with no muffler while wearing a headset. To mount the muffler, I removed the seats & floor aft of the main spar. Ma= rilyn helped me install 8 -3 anchor nuts to the floor where it's doubled a= t 2 longitudinal bulkheads, then bolted on 4 each Ford tailpipe hangers to = the fuselage bottom that contain rubber blocks to hold 3/8" rods. 3/8" mild steel rods were welded to muffler clamps and bent to fit the hang= ers, the ends of the muffler lay in these clamp assemblies. If the U bolts = come loose, the muffler can't fall out. This will cost some air speed, but I hope to save what's left of my hearing= . -----Original Message----- From: shipchief To: Rotary motors in aircraft Sent: Sun, Feb 16, 2014 5:54 pm Subject: [FlyRotary] Re: Sound Level Testing 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 =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_8D0FDA156BA37DA_27B0_32E18_webmail-m151.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii"
Today I assembled enough bits to try out the Aero-turbine 2525 muffler= .
I didn't like the way the ball joints & pipes were fitting, so I r= econfigured that after the test, but I did run it in front of the hangar fo= r a few minutes, and it is now much quieter. In fact, it seems quieter with= out my headset on that with no muffler while wearing a headset.
To mount the muffler, I removed the seats & floor aft of the main = spar.  Marilyn helped me install 8  -3 anchor nuts to t= he floor where it's doubled at 2 longitudinal bulkheads, then bolted o= n 4 each Ford tailpipe hangers to the fuselage bottom that contai= n rubber blocks to hold 3/8" rods.
3/8" mild steel rods were welded to muffler clamps and bent to fit the= hangers, the ends of the muffler lay in these clamp assemblies. If the U b= olts come loose, the muffler can't fall out.
This will cost some air speed, but I hope to save what's left of = my hearing.
-----Original Message-----
From: shipchief <shipchief@aol.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, Feb 16, 2014 5:54 pm
Subject: [FlyRotary] Re: Sound Level Testing

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 <ceengland= 7@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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