X-Virus-Scanned: clean according to Sophos on Logan.com From: "Neil Unger" Received: from nschwmtas02p.mx.bigpond.com ([61.9.189.140] verified) by logan.com (CommuniGate Pro SMTP 6.1.12) with ESMTPS id 9045889 for flyrotary@lancaironline.net; Tue, 18 Oct 2016 16:20:36 -0400 Received-SPF: pass receiver=logan.com; client-ip=61.9.189.140; envelope-from=neil.unger@bigpond.com Received: from nschwcmgw06p ([61.9.190.166]) by nschwmtas02p.mx.bigpond.com with ESMTP id <20161018202015.OBPQ2129.nschwmtas02p.mx.bigpond.com@nschwcmgw06p> for ; Tue, 18 Oct 2016 20:20:15 +0000 Received: from UserPC ([124.176.116.26]) by nschwcmgw06p with BigPond Outbound id x8LE1t00l0aEt2s018LEQc; Tue, 18 Oct 2016 20:20:15 +0000 X-Authority-Analysis: v=2.1 cv=e//7Mvd/ c=1 sm=1 tr=0 a=1mhMOW7J/ei3VWSOCgRf5Q==:117 a=1mhMOW7J/ei3VWSOCgRf5Q==:17 a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=Ia-xEzejAAAA:8 a=H4R7e9ARAAAA:20 a=HoS10J5-dGUeiSgKt90A:9 a=QEXdDO2ut3YA:10 a=vnREMb7VAAAA:8 a=xBU8YhbGxe-B1fX3HlMA:9 a=rtxO7pu9ISJHqu_n:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=5Bgff4Kq9qTR9R7RPwaE:22 Message-ID: <1C122014CFAC4BE2B1C1A7CA0B7D8E7C@UserPC> To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Just a bit of a update Date: Wed, 19 Oct 2016 07:19:28 +1100 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01D229D9.211B3940" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3555.308 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3555.308 This is a multi-part message in MIME format. ------=_NextPart_000_0007_01D229D9.211B3940 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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=20 Sent: Tuesday, October 18, 2016 12:04 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Just a bit of a update Neil, =20 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=20 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,=20 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. =20 On 10/18/2016 9:58 AM, William Jepson wrote: Charlie,=20 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,=20 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?=20 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.=20 Try this package on for size. https://www.youtube.com/watch?v=3DEfreUJt-Fsk. Think you will find it interesting. Bill ------=_NextPart_000_0007_01D229D9.211B3940 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Bill I get the basic idea, byut what size and volumes are we = talking? =20 Will it fit under the aeroplane cowl??  That appears to be the=20 problem.  Neil.
 
Sent: Tuesday, October 18, 2016 12:04 PM
Subject: [FlyRotary] Re: Just a bit of a = update
 
Neil, =20
Helmholtz resonators are used to either amplify or attenuate = sounds. They=20 describe it fairly well on Wicapedia. The idea is to use chambers that = tune to=20 the high frequency to kill the highs. The volumes are critical. The = muffler is a=20 bit clipped in the video, but the volume when the camera is looking over = the=20 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=20 quiet it does not even sound like a rotary.  Do you have diagram = of a=20 description??  Allow that I am an idiot so all details = needed. =20 Neil.

 
On 10/18/2016 10:34 = AM,=20 William Jepson wrote:
Neil,=20
The muffler in the video. It was designed using Helmholtz = principles=20 and it works very well at reducing the high frequencies from the=20 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=20 where??  Everything else on the Rotary can be handled,  = Cooling,=20 mounting, P porting etc, but mufflers have me beaten.  They = are the=20 next for me to investigate particularly how to keep small if=20 possible,  The size in most cases affects how the engine = mount can be=20 constructed on that side.

Thanks in anticip[ation,  Neil. 

 
On=20 10/18/2016 9:58 AM, William Jepson wrote:
Charlie,=20
Pardon my haste in the original reply. The butterflies are = very=20 similar to the original, with the exception that we have devised = a new=20 way to make them that doesn't require drilling through the = housings.=20 Can't say more right now other than we do NOT use epoxy in the = housings=20 and NO sealing problems. Don't expect any. Also we DO NOT weld = to the=20 liner as sometimes pushed by others. I do not believe you can = weld to=20 the liner without catastrophic failure later. I believe you will = either=20 fail your apex seals or crack the weld due to crystallization of = the=20 steel. The muffler is a MAJOR win. It is quieter than a = unmuffled Lyc,=20 and successfully kills the annoying hi frequencies. It is more=20 restrictive than some but only costs us a few HP. It also fits = in an=20 RV-3! I am experimenting with a larger version in hopes of = repeating the=20 success with a bit less restriction on cowls that aren't as = tight as the=20 RV-3
Bill
 
On Mon, Oct 17, 2016 at 3:15 PM, = Charlie England=20 <flyrotary@lancaironline.net> = wrote:
Hi Bill,=20
 
Thanks for the link. I've been following it on the = Homebuilt=20 Airplanes forum; are you 'billsrv4' over there?
 
I've been trying to find a throttle mechanism in the = video, but=20 don't see one. Are they using the custom 'in the housing' = butterflies,=20 like the original Powersport engine?
 
Have you heard it run in person? If so, does the muffler = work as=20 well as it seems to in the video? (Hard to know how much the = audio is=20 clipped in level on a recording.)
 
Thanks,
 
Charlie
 
On Mon, Oct 17, 2016 at 4:52 PM, = William Jepson=20 <flyrotary@lancaironline.net> = wrote:
Since it has been so quiet thought I would = make some=20 noise.=20
Try this package on for size.
 https://www.youtube.com/watch?v=3DEfreUJt-Fsk.
Think=20 you will find it interesting.
Bill
 
=
 

=
 

 
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