REFLECTOR: Exhaust noise

[Scott Derrick]

The tips of my pipes are cut at an angle see pic lowercowlremovedleft.jpg

Clinton at Custom Aircraft who made my exhaust recommends something like 
the second image. He says the bend will noticeably reduce the noise and 
have very little effect on back pressure.  It also will speed up the 
plane. That exhaust plume sticking straight out the bottom of the plane 
is like a huge stick.

It appears that more and more airports are going to be monitoring for 
noise. Which means we need an effective short pipe noise limiter or 
reducer.  Possibly modeled after a gun silencer, which I've heard 
reduces the noise as much as 60db!

Scott




-------- Original Message --------
Subject: Re: REFLECTOR: Exhaust noise
From: David Rene Dugas <renedugas at gmail.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Date: 07/13/2012 01:48 PM

> Cutting the end of the exhaust stack at an angle on one half of the end so it is not square decreases the noise.  So half of the opening is at 90 degrees with the pipe and the other half is at some angle of at least 15 degrees off.  This is not optimal for tuned exhaust and power recovery but much less noisy.
>
>
>
>
> On Jul 13, 2012, at 11:17 AM, Scott Derrick wrote:
>
>> I'm using a Custom Aircraft exhaust which is fairly similar to the factory supplied exhaust. Basically a 3 into 1 stack for each side with the outlet pipe pointing straight down.  The factory exhaust joins  the 3 together under the forward cylinder. The Custom exhaust joins them under the middle cylinder.
>>
>> I got a noise ticket(warning) in the mail from the KSMO operating authority last month.  They have a 95db limit that they somehow monitor.  They said I put out 95.1 db on one of my departures that day.
>>
>> Anybody else experience this? Any solutions?
>>
>> Scott
>> _______________________________________________
>> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery!  www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>

-- 
Eighty percent of success is showing up.
Woody Allen


-------------- next part --------------
A non-text attachment was scrubbed...
Name: lowercowlremovedleft.jpg
Type: image/jpeg
Size: 23593 bytes
Desc: not available
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20120713/367ad09f/attachment-0002.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Right Manifold 90 tailpipe.jpg
Type: image/jpeg
Size: 40637 bytes
Desc: not available
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20120713/367ad09f/attachment-0003.jpg>