X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [66.219.56.245] (HELO mail.qnsi.net) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4411595 for flyrotary@lancaironline.net; Thu, 29 Jul 2010 18:51:22 -0400 Received-SPF: none receiver=logan.com; client-ip=66.219.56.245; envelope-from=bhughes@qnsi.net Content-class: urn:content-classes:message Return-Receipt-To: "Bobby J. Hughes" Subject: RE: [FlyRotary] Re: Noise Measurements MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01CB2F79.2B3EE3E2" Disposition-Notification-To: "Bobby J. Hughes" Date: Thu, 29 Jul 2010 17:52:57 -0600 X-MimeOLE: Produced By Microsoft Exchange V6.5 Message-ID: <74120FDE88CAFE4DBDA8814BCE20A3F3208A2B@qnsi-mail.qnsi.net> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [FlyRotary] Re: Noise Measurements Thread-Index: AcsvbhvzpAUGtlB7S6qerYxFNwLdnwAALXwg References: From: "Bobby J. Hughes" To: "Rotary motors in aircraft" This is a multi-part message in MIME format. ------_=_NextPart_001_01CB2F79.2B3EE3E2 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Steve, =20 That "sounds" great. I hope the packing holds up. Can it be repacked = easily? The Austin bunch is going through Hushpower II resonators pretty = fast. I'm on my second one and it's starting to sound different. I think = Dennis H is down to just a can without any internals. But his RV7 is = still very quiet. I don't have any issues when keying the mic with my = Lightspeed. I only have one flight with my new Zulu and it works great. = Better than my 20XL that's gone missing.=20 =20 Bobby Hughes RV10 Super Renesis=20 =20 ________________________________ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On = Behalf Of Steve Thomas Sent: Thursday, July 29, 2010 4:31 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Noise Measurements Well, I just made a guess and measured it at 100 ft. I'll measure = cockpit noise later, when I've got some flight time in. Here is my = story:=20 I have a Glasair Super II RG with a Mistral 2 rotor engine. I've had it = in the air once, and landed immediately as there was an oil temp problem = that turned out to be a measurement problem. However, what I did find = that was particularly annoying was the noise. My LightSpeed Zulu = handled the noise fine until I keyed the mic. Man, what a blast of = noise! I could barely hear the tower. =20 The muffler that I was using was a 2 1/2 inlet/outlet and 3 1/2" = diameter Burns Stainless device that I purchased many moons ago. It was = made up with stainless scrubble innards. So, I decided to replace it = with another Burns Stainless muffler, but a 2 1/2" inlet/outlet, 6 1/4" = diameter, dual stage muffler. See: =20 http://www.burnsstainless.com/sm-300-625-17-2s.aspx Although this one has a 3" inlet/outlet, they made one for me with the 2 = 1/2". What a difference!!!! Here are the measurements I took from 100 = feet, off the wing tip and about 30=BA aft. They also put in a = stainless cloth material instead of the stainless scrubble. They claim = that it works great for the rotary. =20 idle: 57-60 DB 1500 RPM: 78 DB 2000 RPM: 87DB By RPM, I mean prop at 2.85-1 reduction ratio. I was fearful that going = any higher would put my prop too close to the ground as the nose gear = compressed down with power. I suppose you math-types can extrapolate = different distances. =20 I'll be hitting the air tomorrow. While I had one short flight already, = this will be much longer, hopefully and I can see what the plane will = do. The only real disadvantage of the muffler is that it hangs underneath = the belly and looks ugly. But it, so far, works terrific. I hope the = drag penalty is not too great. =20 BTW, the rest of my exhaust consists of 2" headers into a collector with = a 2 1/2" outlet made with .065 321 SS. =20 Best Regards, Steve Thomas _______________________________________________________ On Jul 29, 2010, at 12:52 PM, wrjjrs@aol.com wrote: =09 Steve, =20 Typically the measurement for cars and motorcycles is at 50 feet away = at 90 degrees to the directin of the exhaust flow. Any in-cabin = measurements wouldn't need orientation, just put the pick up about where = your head is. =20 Bill Jepson =09 =09 -----Original Message----- From: Steve Thomas To: Rotary motors in aircraft Sent: Thu, Jul 29, 2010 9:31 am Subject: [FlyRotary] Noise Measurements =09 =09 I want to take some noise measurements today with a new muffler I just=20 installed. What is a reasonable distance from the aircraft to be = taking these=20 measurements? Right next to the airplane seems to be somewhat = unreasonable, and=20 distance makes a big difference. =20 =09 Best Regards, =09 Steve Thomas _______________________________________________________ =09 =09 =09 =09 =09 =09 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html =09 ------_=_NextPart_001_01CB2F79.2B3EE3E2 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Steve,
 
That "sounds" great. I hope the packing holds up. = Can it be=20 repacked easily? The Austin bunch is going through Hushpower II = resonators=20 pretty fast. I'm on my second one and it's starting to sound different. = I think=20 Dennis H is down to just a can without any internals. But his RV7 = is still=20 very quiet. I don't have any issues when keying the = mic with my=20 Lightspeed.  I only have one flight with my new Zulu and it works = great.=20 Better than my 20XL that's gone missing.
 
Bobby Hughes
RV10 Super Renesis
 

From: Rotary motors in aircraft=20 [mailto:flyrotary@lancaironline.net] On Behalf Of Steve=20 Thomas
Sent: Thursday, July 29, 2010 4:31 PM
To: = Rotary=20 motors in aircraft
Subject: [FlyRotary] Re: Noise=20 Measurements

Well, I just made a guess and measured it at 100 ft. =  I'll=20 measure cockpit noise later, when I've got some flight time in. =  Here is my=20 story:

I have a Glasair Super II RG with a Mistral 2 rotor engine. =  I've had=20 it in the air once, and landed immediately as there was an oil temp = problem that=20 turned out to be a measurement problem.  However, what I did find = that was=20 particularly annoying was the noise.  My LightSpeed Zulu handled = the noise=20 fine until I keyed the mic.  Man, what a blast of noise!  I = could=20 barely hear the tower.  

The muffler that I was using was a 2 1/2 inlet/outlet and 3 1/2" = diameter=20 Burns Stainless device that I purchased many moons ago.  It was = made up=20 with stainless scrubble innards.  So, I decided to replace it with = another=20 Burns Stainless muffler, but a 2 1/2" inlet/outlet, 6 1/4" diameter, = dual stage=20 muffler.   See:  

http://www.b= urnsstainless.com/sm-300-625-17-2s.aspx

Although this one has a 3" inlet/outlet, they made one for me with = the 2=20 1/2".  What a difference!!!!  Here are the measurements I took = from=20 100 feet, off the wing tip and about 30=BA aft.  They also put in a = stainless=20 cloth material instead of the stainless scrubble.  They claim that = it works=20 great for the rotary.   

idle:  57-60 DB
1500 RPM:  78 DB
2000 RPM:  87DB

By RPM, I mean prop at 2.85-1 reduction ratio.  I was fearful = that=20 going any higher would put my prop too close to the ground as the nose = gear=20 compressed down  with power.  I suppose you math-types can = extrapolate=20 different distances.  

I'll be hitting the air tomorrow.  While I had one short = flight=20 already, this will be much longer, hopefully and I can see what the = plane will=20 do.

The only real disadvantage of the muffler is that it hangs = underneath the=20 belly and looks ugly.  But it, so far, works terrific.  I hope = the=20 drag penalty is not too great.  

BTW, the rest of my exhaust consists of 2" headers into a collector = with a=20 2 1/2" outlet made with .065 321 SS.  

Best Regards,

Steve Thomas
__________________________________________= _____________


=

On Jul 29, 2010, at 12:52 PM, wrjjrs@aol.com wrote:
Steve,
 
Typically the measurement for cars and motorcycles is at 50 feet = away at=20 90 degrees to the directin of the exhaust flow. Any in-cabin = measurements=20 wouldn't need orientation, just put the pick up about where your head=20 is.
 
Bill Jepson



-----Original=20 Message-----
From: Steve Thomas <glasair2@me.com>
To: Rotary = motors in=20 aircraft <flyrotary@lancaironline.net>
Sent:=20 Thu, Jul 29, 2010 9:31 am
Subject: [FlyRotary] Noise = Measurements

I want to take some noise measurements =
today with a new muffler I just=20
installed.  What is a reasonable distance from the aircraft to be taking =
these=20
measurements?  Right next to the airplane seems to be somewhat =
unreasonable, and=20
distance makes a big difference. =20

Best Regards,

Steve Thomas
_______________________________________________________






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