X-Virus-Scanned: clean according to Sophos on Logan.com From: "Neil Unger" Received: from nsstlmta01p.bpe.bigpond.com ([203.38.21.1] verified) by logan.com (CommuniGate Pro SMTP 6.1.12) with ESMTPS id 9046999 for flyrotary@lancaironline.net; Wed, 19 Oct 2016 01:04:23 -0400 Received-SPF: pass receiver=logan.com; client-ip=203.38.21.1; envelope-from=unger1948@bigpond.com Received: from smtp.telstra.com ([10.10.24.4]) by nsstlfep01p-svc.bpe.nexus.telstra.com.au with ESMTP id <20161019050402.STEJ7728.nsstlfep01p-svc.bpe.nexus.telstra.com.au@smtp.telstra.com> for ; Wed, 19 Oct 2016 16:04:02 +1100 X-CTCH-RefID: str=0001.0A150209.5806FEC2.0076,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-VOD: Unknown X-CTCH-Spam: Unknown X-Authentication-Info: Submitted using ID unger1948@bigpond.com Received: from [10.0.0.136] (120.146.81.77) by smtp.telstra.com (9.0.018.03.01) (authenticated as unger1948@bigpond.com) id 578C23E704FBCCC0 for flyrotary@lancaironline.net; Wed, 19 Oct 2016 16:04:02 +1100 Subject: Re: [FlyRotary] Re: Just a bit of a update To: Rotary motors in aircraft References: Message-ID: <48cf894d-eb4e-2925-7f51-211a0458d4a6@bigpond.com> Date: Wed, 19 Oct 2016 16:03:14 +1100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------9A6715113E51BD34285D0490" This is a multi-part message in MIME format. --------------9A6715113E51BD34285D0490 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Thanks Bill, I would prefer you to spend the time anyway. Thanks for intro, but have a new one myself which "fits" but I am not expecting much noise reduction. Will know shortly. Neil. On 10/19/2016 8:23 AM, William Jepson wrote: > Neil, > Revisit the video. The muffler in the video is shown fairly obviously > in one of the pans. That muffler was designed to fit in an RV-3! > Pretty small space there. The slightly odd shape is to allow airflow > around it and out. I have photos of the plane with the engine hung, > but I promised my partner that these would not circulate until the > plane is flying and proven. While I wanted to show some of what is > going on we do not want to be one of many "smoke and mirrors" > builders. This is intended to return a proven platform. I have perfect > solidworks drawings of the muffler as well, but same situation. > > Bill > > On Tue, Oct 18, 2016 at 1:19 PM, Neil Unger > > wrote: > > Bill I get the basic idea, byut what size and volumes are we > talking? Will it fit under the aeroplane cowl?? That appears to > be the problem. Neil. > *From:* William Jepson > *Sent:* Tuesday, October 18, 2016 12:04 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Just a bit of a update > Neil, > Helmholtz resonators are used to either amplify or attenuate > sounds. They describe it fairly well on Wicapedia. The idea is to > use chambers that tune to the high frequency to kill the highs. > The volumes are critical. The muffler is a bit clipped in the > video, but the volume when the camera is looking over the RV-4 > with dyno in the background is a good representation. > Bill > On Mon, Oct 17, 2016 at 4:38 PM, Neil Unger > > > wrote: > > Bill, what are Helmholtz principles?? The muffler at 6000 rpm > was so quiet it does not even sound like a rotary. Do you > have diagram of a description?? Allow that I am an idiot so > all details needed. Neil. > > On 10/18/2016 10:34 AM, William Jepson wrote: >> Neil, >> The muffler in the video. It was designed using Helmholtz >> principles and it works very well at reducing the high >> frequencies from the rotary. >> Bill >> On Mon, Oct 17, 2016 at 4:18 PM, Neil Unger >> > > wrote: >> >> Bill, Now you have got my interest, What muffler and >> where?? Everything else on the Rotary can be handled, >> Cooling, mounting, P porting etc, but mufflers have me >> beaten. They are the next for me to investigate >> particularly how to keep small if possible, The size in >> most cases affects how the engine mount can be >> constructed on that side. >> >> Thanks in anticip[ation, Neil. >> >> On 10/18/2016 9:58 AM, William Jepson wrote: >>> Charlie, >>> Pardon my haste in the original reply. The butterflies >>> are very similar to the original, with the exception >>> that we have devised a new way to make them that doesn't >>> require drilling through the housings. Can't say more >>> right now other than we do NOT use epoxy in the housings >>> and NO sealing problems. Don't expect any. Also we DO >>> NOT weld to the liner as sometimes pushed by others. I >>> do not believe you can weld to the liner without >>> catastrophic failure later. I believe you will either >>> fail your apex seals or crack the weld due to >>> crystallization of the steel. The muffler is a MAJOR >>> win. It is quieter than a unmuffled Lyc, and >>> successfully kills the annoying hi frequencies. It is >>> more restrictive than some but only costs us a few HP. >>> It also fits in an RV-3! I am experimenting with a >>> larger version in hopes of repeating the success with a >>> bit less restriction on cowls that aren't as tight as >>> the RV-3 >>> Bill >>> On Mon, Oct 17, 2016 at 3:15 PM, Charlie England >>> >> > wrote: >>> >>> Hi Bill, >>> Thanks for the link. I've been following it on the >>> Homebuilt Airplanes forum; are you 'billsrv4' over >>> there? >>> I've been trying to find a throttle mechanism in the >>> video, but don't see one. Are they using the custom >>> 'in the housing' butterflies, like the original >>> Powersport engine? >>> Have you heard it run in person? If so, does the >>> muffler work as well as it seems to in the video? >>> (Hard to know how much the audio is clipped in level >>> on a recording.) >>> Thanks, >>> Charlie >>> On Mon, Oct 17, 2016 at 4:52 PM, William Jepson >>> >> > wrote: >>> >>> Since it has been so quiet thought I would make >>> some noise. >>> Try this package on for size. >>> https://www.youtube.com/watch?v=EfreUJt-Fsk >>> . >>> Think you will find it interesting. >>> Bill >>> >> > > --------------9A6715113E51BD34285D0490 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit

Thanks Bill,  I would prefer you to spend the time anyway.  Thanks for intro, but have a new one myself which "fits" but I am not expecting much noise reduction.  Will know shortly.  Neil.


On 10/19/2016 8:23 AM, William Jepson wrote:
Neil,
Revisit the video. The muffler in the video is shown fairly obviously in one of the pans. That muffler was designed to fit in an RV-3! Pretty small space there. The slightly odd shape is to allow airflow around it and out. I have photos of the plane with the engine hung, but I promised my partner that these would not circulate until the plane is flying and proven. While I wanted to show some of what is going on we do not want to be one of many "smoke and mirrors" builders. This is intended to return a proven platform. I have perfect solidworks drawings of the muffler as well, but same situation.

Bill

On Tue, Oct 18, 2016 at 1:19 PM, Neil Unger <flyrotary@lancaironline.net> wrote:
Bill I get the basic idea, byut what size and volumes are we talking?  Will it fit under the aeroplane cowl??  That appears to be the problem.  Neil.
 
Sent: Tuesday, October 18, 2016 12:04 PM
Subject: [FlyRotary] Re: Just a bit of a update
 
Neil, 
Helmholtz resonators are used to either amplify or attenuate sounds. They describe it fairly well on Wicapedia. The idea is to use chambers that tune to the high frequency to kill the highs. The volumes are critical. The muffler is a bit clipped in the video, but the volume when the camera is looking over the RV-4 with dyno in the background is a good representation.
Bill
 
On Mon, Oct 17, 2016 at 4:38 PM, Neil Unger <flyrotary@lancaironline.net> wrote:

Bill, what are Helmholtz principles??  The muffler at 6000 rpm was so quiet it does not even sound like a rotary.  Do you have diagram of a description??  Allow that I am an idiot so all details needed.  Neil.

 
On 10/18/2016 10:34 AM, William Jepson wrote:
Neil,
The muffler in the video. It was designed using Helmholtz principles and it works very well at reducing the high frequencies from the rotary.
Bill
 
On Mon, Oct 17, 2016 at 4:18 PM, Neil Unger <flyrotary@lancaironline.net> wrote:

Bill,  Now you have got my interest,  What muffler and where??  Everything else on the Rotary can be handled,  Cooling, mounting, P porting etc, but mufflers have me beaten.  They are the next for me to investigate particularly how to keep small if possible,  The size in most cases affects how the engine mount can be constructed on that side.

Thanks in anticip[ation,  Neil. 

 
On 10/18/2016 9:58 AM, William Jepson wrote:
Charlie,
Pardon my haste in the original reply. The butterflies are very similar to the original, with the exception that we have devised a new way to make them that doesn't require drilling through the housings. Can't say more right now other than we do NOT use epoxy in the housings and NO sealing problems. Don't expect any. Also we DO NOT weld to the liner as sometimes pushed by others. I do not believe you can weld to the liner without catastrophic failure later. I believe you will either fail your apex seals or crack the weld due to crystallization of the steel. The muffler is a MAJOR win. It is quieter than a unmuffled Lyc, and successfully kills the annoying hi frequencies. It is more restrictive than some but only costs us a few HP. It also fits in an RV-3! I am experimenting with a larger version in hopes of repeating the success with a bit less restriction on cowls that aren't as tight as the RV-3
Bill
 
On Mon, Oct 17, 2016 at 3:15 PM, Charlie England <flyrotary@lancaironline.net> wrote:
Hi Bill,
 
Thanks for the link. I've been following it on the Homebuilt Airplanes forum; are you 'billsrv4' over there?
 
I've been trying to find a throttle mechanism in the video, but don't see one. Are they using the custom 'in the housing' butterflies, like the original Powersport engine?
 
Have you heard it run in person? If so, does the muffler work as well as it seems to in the video? (Hard to know how much the audio is clipped in level on a recording.)
 
Thanks,
 
Charlie
 
On Mon, Oct 17, 2016 at 4:52 PM, William Jepson <flyrotary@lancaironline.net> wrote:
Since it has been so quiet thought I would make some noise.
Try this package on for size.
Think you will find it interesting.
Bill
 
 

 

 


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