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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 9:00 am 
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Getting ready to cut the exhaust exits in the cowling. What is the current thinking on least drag most functional installation. I have previously built metal farings with 1 inch clearance on all sides, but these seemed a bit big. I have noted that too little clearance results in paint blistering.....so what is best. I am always intrigued by the long exhaust on the Cirrus....3-4ft pointing aft. What is the fastest, most functional, and best looking. Have considered cutting flush with the cowling with no farings, but not sure about the aerodynamic wisdom of this. Help me out o-experienced ones.

Scott

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


Last edited by Anonymous on Thu Dec 23, 2010 9:00 am, edited 1 time in total.

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leewwalton
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 9:21 am 
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Here you go Dr. this should fuel the conversation a bit ...

Image

Lee Walton

Image

John Walton

Image

Bob Highley

Image

Bill Williams

Image

John Evens

Image

Gary Green

Yes, I take a lot of pictures!

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Lee Walton
Houston, TX
N51863,N118LW
KEFD


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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 10:14 am 
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Outstanding photo summary. You do take a lot of pictures. You wouldn't happen to have a pic of my 1967 mustang I had back in High School.......never took any good pics of that one.

Looks like the exhaust examples you displayed are pretty tight...not much airflow around the pipes, and not much for elaborate farings, except for GG. I know that he recessed his floorboards and made a faring. I guess the pipes themselves act like their own farings.....on some examples. What would speed with economy dictate.

SS

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


Last edited by admin on Thu Dec 23, 2010 10:14 am, edited 1 time in total.

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Fraser MacPhee
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 11:14 am 
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Scott - witness the drag video posted yesterday - suspect fairings are more prone to increasing speed.

Has anyone ever seen a spec of anything on John Evens' plane?

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Fraser MacPhee
N926WM
Serial #279-1
Draper, UT


Last edited by admin on Thu Dec 23, 2010 11:14 am, edited 1 time in total.

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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 11:17 am 
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Actually I did see a smudge of grease on Johns plane once....as it turns out it was grease on my face reflecting off of one of his polished stainless steel abrasion plates. My mistake. I bet Lee has a pic of that too.

SS

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 11:39 am 
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Gary, what did you do to keep your paint from peeling off of your exhaust farings...insulation....silicon.....magic.

SS

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


Last edited by admin on Thu Dec 23, 2010 11:39 am, edited 1 time in total.

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Gary Green
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 12:51 pm 
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Scott; I did nothing except provide about 1/2" clearance around the pipe. I suspect if you got it closer than that it might blister.


Last edited by admin on Thu Dec 23, 2010 12:51 pm, edited 1 time in total.

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qjayz
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 2:19 pm 
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Joined: Sun Jul 11, 2010 6:08 pm
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From what I understand tubes are very un-aerodynamic, and was wondering about the wisdom of using streamline steel "strut tubing" for the protruding exhaust stacks. This seems like it would solve the drag problem without needing a fairing. Any opinions/suggestions?

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Quincy Zlotnick
Sebastopol CA
plans #576


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Rich Brazell
 Post subject: Exhaust Exit
PostPosted: Thu Dec 23, 2010 3:41 pm 
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If you are concerned about "blistering" you can get some "heat proof tape" from Spruce... Woven fiberglass tape. 2" w x 1/16" thick. 87 cents by the foot. Even though it sez tape, it has no adhesive on it, tape probably refers to the size of it. I plan to expoxy a small strip to the inside of my exhaust cuffs. Probably not necessary, but easier than trying to repair blistered fiberglass and a lot less expensive. Only a couple of bucks for peace of mind. [;)]

RB


Last edited by admin on Thu Dec 23, 2010 3:41 pm, edited 1 time in total.

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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Wed Jan 12, 2011 9:34 am 
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Her was my version. Farings made out of 2024T0....very soft and easy to work with 032. Stiffened up nicely after forming. Was going to use 6061t0 but was out of stock. Hopefully this will be ok.

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


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Rich Brazell
 Post subject: Exhaust Exit
PostPosted: Wed Jan 12, 2011 2:18 pm 
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You should mass produce these babies ! Very nice.

RB


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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Wed Jan 12, 2011 10:14 pm 
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Thanks RB. I would be happy to but......I think that each exhaust would be different. Different exit angle. Different distance from the firewall. Etc. Mine are three inch diameter to give 1/2 in clearence around the pipes and about 11in long without the flange and about 12in long with the flange. Would be happy to send the form out if anyone wants to give it a try, it is pretty easy. The key is the metal. Tried to make several for Roy out of 6061 T4 but even when annealed with a torch it got wavy and looked rough. The T0 is like hammering butter. Just hope it is stiff enough......ah the cry of every man over 40.

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


Last edited by admin on Wed Jan 12, 2011 10:14 pm, edited 1 time in total.

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tubetwister
 Post subject: Exhaust Exit
PostPosted: Wed Jan 12, 2011 11:34 pm 
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Joined: Wed Oct 21, 2009 11:58 am
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Nice job Scott. look great. On your annealing process, 6061 t4 or t6 usually very easy to anneal, me thinks you are getting it way too hot. I recommend using an oxy/acy torch (I prefer to use a small rosebud) light the torch and with a soft, acy only flame, soot your alum.(turn it black with the soot), then set your torch for a soft neutral flame, and heat the area you want to anneal just enough to "burn off" the soot in the area. Most common mistake is people get it way too hot, thinking along the lines of copper or steel annealing, and that will cause warpage! It is easy to get too hot.. Practice on some scraps first. I like annealing 6061, easy to get to deadsoft (T0) and then comes back a little harder with work. I love to see people forming metal!!


Last edited by admin on Wed Jan 12, 2011 11:34 pm, edited 1 time in total.

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Bill Williams
 Post subject: Exhaust Exit
PostPosted: Thu Jan 13, 2011 5:26 am 
When annealing, use a 1" magic marker, blacken the metal, use the same technic with torch to anneal, burn the markers black off,moving the flame rapidly over the metal, same results but without all the soot, grease from the soot and black metal, just plain soft, clean metal.


Last edited by admin on Thu Jan 13, 2011 5:26 am, edited 1 time in total.

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Scott Stine
 Post subject: Exhaust Exit
PostPosted: Thu Jan 13, 2011 10:16 am 
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Joined: Wed Oct 21, 2009 9:57 pm
Posts: 54
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Thanks for the tips. May have to try again with the 6061 T4 and anneal it with the torch. I love the looks of the ones I made with the T 0 but I will try a set done with T 4 annealed just for fun.

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Scott Stine
Vincennes, IN
812-881-7923
Arrow 545WA


Last edited by admin on Thu Jan 13, 2011 10:16 am, edited 1 time in total.

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