REFLECTOR: Exhaust noise

[David Rene Dugas]

I see what you mean.  I have no experience with an angle all the way across the pipe.  I was talking about an angle half way across the opening.  I don't know if it makes a difference.
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FWIW
Rene'


On Jul 13, 2012, at 5:23 PM, Scott Derrick wrote:

> 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
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>> 
>> 
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> 
> -- 
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> 
> 
> <lowercowlremovedleft.jpg><Right Manifold 90 tailpipe.jpg>_______________________________________________
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