X-Virus-Scanned: clean according to Sophos on Logan.com From: "Charlie England" Received: from mail-yw0-f178.google.com ([209.85.161.178] verified) by logan.com (CommuniGate Pro SMTP 6.1.12) with ESMTPS id 9043255 for flyrotary@lancaironline.net; Mon, 17 Oct 2016 20:15:42 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.161.178; envelope-from=ceengland7@gmail.com Received: by mail-yw0-f178.google.com with SMTP id w3so127427730ywg.1 for ; Mon, 17 Oct 2016 17:15:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to; bh=cA8Bvea6wvMPZQum4ma8zrdDiq5NqypNQBB8HRNI0zA=; b=OvpMozTp8fJU4BfHQMnza+X5CbrM/i+P8Lt1l/K3rlwssXUXeCQK9aNw8rLi0JJuIm JDued5HKrpFTnszd6oAbGU1kLpP0Q6mrUtv+Ig0gIbuTtgBTV+lrTG3D9RLXtWr9swb5 P0rtrb0KH7M/I6Bk6JMVdmqX2TRGGSYwuLuaTXi1GNtyy4LB4h2sKJc5F/L4HJidr0hJ wgn3JMkak5WZ5pHq15NK/2ettZ3nGKN0YYmmyUTNdQ/sQt0U3igHI+LSe+vhK7JpBQ/7 VcrFAui2xOuMCUpldHJ0BaIPPKErib4G7bEprCAfFiNPtmbC+d0Lbfm5CEdS6C8Kc98k lmVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to; bh=cA8Bvea6wvMPZQum4ma8zrdDiq5NqypNQBB8HRNI0zA=; b=UMByoIsoCsFZcq/wM4bdaGiS6XWKIzZH3Cy8vYm5JgoOYO8zQRHZWaV7lrFoYl1e1y oOUMfdZTS31ZXrSeLf6FZ4/RmPA9gdEmzjUN39r2fgbsW9O/MidLYYWRa8JjFbI3ELGx wdGJXnmVcTNYPPzmP0bigNQ1pGOyYkrtvvXzPjl6BykdLRQoc7cad4m7YXk/7GDBDYHV v6KoT0LGnTSHYz/JAUX8tYcSM1Ef8ugraP0LyuzvdNdPsmo5b7cP7IlS0yyVA012vuBf mhJueEMsxsntlZJaRV6mE9oeefXcSycuWG4MWGQrvvFHDFsKrpSK7SE8oRSa6EP+zhYl wrSA== X-Gm-Message-State: AA6/9RkTXs92YToT5KPyvusLGEqkE+TqC7zOG43sHG8jDedp8OblAz4a3i7hYU17QyTFgw== X-Received: by 10.13.204.19 with SMTP id o19mr166096ywd.148.1476749724578; Mon, 17 Oct 2016 17:15:24 -0700 (PDT) Return-Path: Received: from [192.168.10.228] (adsl-98-95-172-156.jan.bellsouth.net. [98.95.172.156]) by smtp.googlemail.com with ESMTPSA id b188sm12804997ywc.16.2016.10.17.17.15.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Oct 2016 17:15:24 -0700 (PDT) Subject: Re: [FlyRotary] Re: Just a bit of a update To: Rotary motors in aircraft References: Message-ID: Date: Mon, 17 Oct 2016 19:15:34 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------E6648AAB43BC2C9E8FB5A707" This is a multi-part message in MIME format. --------------E6648AAB43BC2C9E8FB5A707 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Hi Neil, To save Bill some time, here ya go: https://en.wikipedia.org/wiki/Helmholtz_resonance https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=helmholtz%20resonator If you've ever blown across the mouth of a bottle to hear it resonate, that's an example. A ported loudspeaker enclosure is another. Most intake manifolds these days have them somewhere in there, as well; sometimes for induction tuning, other times to silence the noise of the intake. Many years ago, Monty Roberts & I played around with a real time spectrum analyzer at one of Tracy Crook's flyins with the (stillborn) goal of doing what Bill's group has apparently accomplished. There are other ways to strip off the nasty high frequencies, but most of them are heavy. A builder here in the USA once ran a stock cast iron manifold without a muffler (just a ~8" stub pipe on the end) on a canard pusher, and it had a very pleasant sound similar to a small block V-8. Charlie On 10/17/2016 6:38 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 >>> >>> >>> >> >> > --------------E6648AAB43BC2C9E8FB5A707 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
Hi Neil,

To save Bill some time, here ya go:

https://en.wikipedia.org/wiki/Helmholtz_resonance

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=helmholtz%20resonator

If you've ever blown across the mouth of a bottle to hear it resonate, that's an example. A ported loudspeaker enclosure is another. Most intake manifolds these days have them somewhere in there, as well; sometimes for induction tuning, other times to silence the noise of the intake.

Many years ago, Monty Roberts & I played around with a real time spectrum analyzer at one of Tracy Crook's flyins with the (stillborn) goal  of doing what Bill's group has apparently accomplished.

There are other ways to strip off the nasty high frequencies, but most of them are heavy. A builder here in the USA once ran a stock cast iron manifold without a muffler (just a ~8" stub pipe on the end) on a canard pusher, and it had a very pleasant sound similar to a small block V-8.

Charlie

On 10/17/2016 6:38 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 <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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