X-Virus-Scanned: clean according to Sophos on Logan.com From: "William Jepson" Received: from mail-vk0-f49.google.com ([209.85.213.49] verified) by logan.com (CommuniGate Pro SMTP 6.1.12) with ESMTPS id 9043314 for flyrotary@lancaironline.net; Mon, 17 Oct 2016 21:04:28 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.213.49; envelope-from=wrjjrs@gmail.com Received: by mail-vk0-f49.google.com with SMTP id 2so199023054vkb.3 for ; Mon, 17 Oct 2016 18:04:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=76/a51ZfkkTjFeWbmE3P5IGpW4ImoNx9ZJcWvdBDRIo=; b=iuW7+2Saq/b9XDvINdczELDfNeENjbQVZ5p7dWtt7aK0F5YirvjkRNHySWfhByI1Z5 Zr5obaRDBZiefJKTO7pHMTqxFtZFtHHFd6zfdo2sipmVW9Us6x85Ktof6WnDS7LyB+bL KK+IIfR1FDGeUHwKPp++9CevKCREHV2qhWybfiNyy8BhChwvM/BclpToMGTvu2i+hV90 gOvJjEqu3d0ndsJWriOSEEMVveTYad3hw8Ojp+cSf0Xj9Mr+e6A6dg0B329ycdpvCWF6 hdda67IU91gEfoPw1nmS/r22f32F/2dkKhQKfS1lzHFQJ9GwPuq71DdB8yqsYYV0EeI4 qV1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=76/a51ZfkkTjFeWbmE3P5IGpW4ImoNx9ZJcWvdBDRIo=; b=Dj7BtcgVLpCTSagCLMDs0Ap6m0E96MReXOStPBqqkTx0oJqJdozJvvy1TLtm86bIaL gGH2LMuCJBCJJudWWnRK0at610PrZFx2aFibQ29KDQdoa/SyG6QeG1fxvC7fSssXm8yi 0kDpC04pt26DUraPDp9PwBWsuuwxilkkWihSfH551QsaxMsxNCQ3v7cpGwTQ38vveQUi jNi6OK0MYmtmPBueWvh0cC7EG5XGPrOyZseVjtCjz3/LB+2Iwh02oOD0rn+ULSTwnBjG hgzPJJPbJikcbO4ueCjlxSTdiL2c9MK2gOaItp0X3ujD0zGBfIN0APuzu2mbb1a2q/FB 4mDA== X-Gm-Message-State: AA6/9RlqknfQaHbfwLl4VRKlyVUgdeQ3l07v1uvVGYfYHH+kjc+uyBrSFZSb0z8t/992twJQ9JEDQHx2Ha1Usw== X-Received: by 10.31.193.20 with SMTP id r20mr289593vkf.44.1476752649354; Mon, 17 Oct 2016 18:04:09 -0700 (PDT) MIME-Version: 1.0 Received: by 10.103.81.201 with HTTP; Mon, 17 Oct 2016 18:04:08 -0700 (PDT) In-Reply-To: References: Date: Mon, 17 Oct 2016 18:04:08 -0700 Message-ID: Subject: Re: [FlyRotary] Re: Just a bit of a update To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=001a114dc090160630053f1945ef --001a114dc090160630053f1945ef Content-Type: text/plain; charset=UTF-8 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 < >> 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. >>>> https://www.youtube.com/watch?v=EfreUJt-Fsk. >>>> Think you will find it interesting. >>>> Bill >>>> >>> >>> >> >> > > --001a114dc090160630053f1945ef Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Neil,=C2=A0
Helmholtz resonators are used to either am= plify or attenuate sounds. They describe it fairly well on Wicapedia. The i= dea is to use chambers that tune to the high frequency to kill the highs. T= he 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 backgroun= d is a good representation.
Bill=C2=A0

On Mon, Oct 17, 2016 at 4:38 PM,= Neil Unger <flyrotary@lancaironline.net> wrote:
=20 =20 =20

Bill, what are Helmholtz principles??=C2=A0 The muffler at 6000 rpm was so quiet it does not even sound like a rotary.=C2=A0 Do you have diagram of a description??=C2=A0 Allow that I am an idiot so all details needed.=C2=A0 Neil.


On 10/18/2016 10:3= 4 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,=C2=A0 Now you have got my interest,=C2=A0 What muffl= er and where??=C2=A0 Everything else on the Rotary can be handled,= =C2=A0 Cooling, mounting, P porting etc, but mufflers have me beaten.=C2=A0 They are the next for me to investigate particularly how to keep small if possible,=C2=A0 The size = in most cases affects how the engine mount can be constructed on that side.

Thanks in anticip[ation,=C2=A0 Neil.=C2=A0


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@lanc= aironline.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?=C2=A0

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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