REFLECTOR: Reflector Digest, Vol 98, Issue 29

[Dave T Nelson]

Geoff, I tack welded some cheap steel exhaust pipe to make a template and
then sent the template to an aircraft exhaust shop for the actual build.  I
can dig up the name if you get interested.  Here are some pictures
(although not great).  As you can see, I do have supports on both sides
near the exhaust end (you might be able to improve on what I did).

(See attached file: Exhaust even side.jpg)(See attached file: Exhaust odd
side.jpg)

Dave

Dave T. Nelson
T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
Program Director, ISC ECAT NPI & Test Engineering

----- Message from Geoff Gerhardt <geoff.gerhardt at gmail.com> on Fri, 10 May
2013 07:07:10 -0400 -----
                                                           
      To: Velocity Aircraft Owners and Builders list       
          <reflector at tvbf.org>                             
                                                           
 Subject: Re: REFLECTOR: Performance                       
                                                           

Dave,

Where did you get your exhaust made?  Do you have some pics showing it with
the cowl off?  I'd like to see how it was routed back.  Is the terminus end
of the exhaust supported in any way?

Thanks a lot for your comments and picture.

Geoff

On Thu, May 9, 2013 at 5:15 PM, Dave T Nelson <dtnelson at us.ibm.com> wrote:
  Richard, I can't point at any NACA or other research, but I changed from
  a "straight out the bottom" to an enclosed aft firing exhaust on my 200
  HP STD-RG.  I picked up at least 10 knots, really more like 15.  I did it
  because all of my EZ friends, and especially the guys I know that race,
  had done it and claimed great results.

  Clearly shooting the exhaust out the bottom creates a big plume of
  disturbed air... I've struggled as to exactly how the force of that "drag
  plume" is translated back to the aircraft... but it sure worked for me.

  Here's a picture of my exhaust.  Yes, I do get soot on my three bladed
  prop.  No, I've never seen any damage issue to the prop from the hot gas
  (after about 400 - 500 hours).

  (See attached file: IMG_1042.jpg)




  Dave

  Dave T. Nelson
  T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
  Program Director, ISC ECAT NPI & Test Engineering

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