REFLECTOR: Performance

Fri May 10 13:59:04 CDT 2013

I have been using Custom Aircraft Parts in Ca. ever since Scott turned me on to them. they have rebuilt my 235 exhaust system as well as built my Velocity exhaust. Great workmanship, great prices, Fast turnaround times. 

http://www.customaircraft.com/

Kurt 

-----Original Message-----
From: Geoff Gerhardt <geoff.gerhardt at gmail.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Fri, May 10, 2013 9:59 am
Subject: Re: REFLECTOR: Performance

Yes, I think I will accept this challenge.  If anyone has any advice on the best AC exhaust company to use I'd appreciate it.  I've seen that many offer to send you put this PVC pipe kit to get it right, then will weld up a ss pipe based on this design.

Any input on 4-4, 2x2-1 or 4-1 configurations would be appreciated.  Also, anyone who has info from longez or cozy implementations of this would be helpful.

Geoff

On Fri, May 10, 2013 at 11:47 AM, Richard J. Gentil <richard at naples-air-center.com> wrote:

I would say we need someone (Geoff, Geoff) who only changes the exhaust and nothing else, runs a test and reports back to the Reflector with the findings

Richard

Sent from my iPhone 5

On May 10, 2013, at 11:38 AM, Kevin Baker <flykb at verizon.net> wrote:

> I would agree.
> This is the type of info I've read about as well on the cozy /long forums with similar results
>
> Thanks
> Kevin Baker
>
> .
>
> On May 10, 2013, at 10:12 AM, David Rene Dugas <renedugas at gmail.com> wrote:
>
>> David,
>> I would suggest that #2 is significant because the large plume of hot exhaust is forcing a dramatic change in direction on a large shout of air traveling at 200 mph. This would act like a speed break.   The energy to move this air would be parasitic drag and would be substantial.   I realize there is no mechanical connection but there is a gaseous connection the same as one has with the earth when in flight so very real. I'm not an engineer so I do not has the formulas to calculate it but my 2 cents worth is that that plume and pipes are a big source of drag. Just my maniacal machinations. 
>>
>> Rene' Dugas
>> Sent from an Apple.
>>
>> On May 10, 2013, at 8:06 AM, "David Ullman" <ullman at robustdecisions.com> wrote:
>>
>>> IF I added up all the speed increases I could get from the topics discussed
>>> here, my plane would be supersonic.
>>>
>>> I too would like to see proof that rear facing exhaust helps.  I have now
>>> heard four theories: 1) the exhaust gas acts like a jet, 2) the
>>> perpendicular flow adds drag, 3) The exhaust disturbs the boundary layer on
>>> the cowl, 4) the exhaust gas disturbs the flow seen by the prop.
>>>
>>> The first one I calculated, and the thrust due to increased velocity of the
>>> exhaust gas is minimal.  For #2, the plum has no way to transfer its drag
>>> back to the plane.  Picture the plume as a cylinder projecting into the
>>> airstream.  It is not connected to the plane in any way to slow it down, so
>>> #2 is out.  The boundary layer at the back of the plane is already well
>>> chewed, so #3 is not much of a possibility.  I hadn't thought of disturbing
>>> the prop flow before.  The wings are already doing a good job of this, could
>>> the exhaust add to this disturbance in a significant manner?   I can see
>>> where moving the exhaust to the hub area (or outside the prop radius) may
>>> have an effect, the first three are just noise.
>>>
>>> David Ullman
>>> N444DX
>>> President EAA 292
>>> 541-760-2338
>>> david at davidullman.com
>>>
>>>
>>> -----Original Message-----
>>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>>> Behalf Of reflector-request at tvbf.org
>>> Sent: Thursday, May 09, 2013 7:47 PM
>>> To: reflector at tvbf.org
>>> Subject: Reflector Digest, Vol 98, Issue 27
>>>
>>> Send Reflector mailing list submissions to
>>>  refle
>
> _______________________________________________
> 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

_______________________________________________
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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20130510/1f73f72b/attachment.html>