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  #21  
Old 12-02-2019, 04:10 PM
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Steve Melton Steve Melton is offline
 
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Quote:
Originally Posted by fixnflyguy View Post
I used 3/8 Stainless tubing which I threaded the inside of the ends and put in Heim bearings similar to the hinges on the flight controls. I then cross drilled a rivet through the shank to prevent any back out of the Heim bearing. A Stainless tab is installed on the sump and the exhaust hanger at the tip bent to the correct angle, then bolt the tube/rod end assembly in. It allows movement, but has no flattened ends to fail. If you are flattening a tube, the best crack prevention is a small piece of steel (1/16"-1/8" thick)looking like a popsicle stick inserted in the tube an inch or so then squeeze the tube over it. This prevents the sharp radius failure point of the flattened tube.
a clever guy
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  #22  
Old 12-02-2019, 05:50 PM
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scrollF4 scrollF4 is offline
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Default What am I looking at, Dan?

Dan,
Help me understand what's in your image.

Is that steel cable you're using to suspend the exhaust?
How long have you used that assembly?
Reasonably easy to fabricate and install?
Benefits?
Cons?
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  #23  
Old 12-02-2019, 06:17 PM
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plehrke plehrke is offline
 
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Quote:
Originally Posted by bruceh View Post
I was doing an oil change today, and as usual, I give the entire engine a really good look over. I found one of the exhaust hangers had cracked.
I had lots of broken Adel clamps but never the flattened rod. No more broken clamps once I realized I was scarring them right at the edge of the bolt in the corner due to the way I was squeezing them to install. Also went to SS clamps from Aluminum.

I like fixnflyguy rod ends idea. May swap out flattened tubes for rod end versions next time cowl is off.
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  #24  
Old 12-02-2019, 06:28 PM
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Quote:
Originally Posted by scrollF4 View Post
Dan,
Help me understand what's in your image.

Is that steel cable you're using to suspend the exhaust?
How long have you used that assembly?
Reasonably easy to fabricate and install?
Benefits?
Cons?
I'm not Dan but that's the same mount I received with the 4 into 1 exhaust I bought from Aerospace Welding. There's 2 SS blocks with horizontal holes welded to a plate that bolts to the fuselage. There are corresponding blocks welded to the clamp that goes around the exhaust pipe. You thread about 3 loops of SS cable on either side of the pipe to connect it to the fuselage blocks. Mine's not flying yet but it looks like the best mount I've seen.
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  #25  
Old 12-02-2019, 08:06 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by turbo View Post
ditto on this method. replaced all my hollow tube supports with solid ones. flattening the end took some work but worth the effort. will never break.
[IMG][/IMG]
Turbo -- I'm just wondering what the significance of the picture is here?
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  #26  
Old 12-02-2019, 11:24 PM
Lars Lars is offline
 
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Adding to the chorus... When I was installing my exhaust system about 10 years ago I saw numerous posts describing broken Vetterman style flattened tube hangers.

Stainless is good for being stainless, but 300 series stuff isn't exactly strong and is relatively brittle and fatigue sensitive compared to other types of steel. Didn't want to have a field failure and/or carry spares.

I bought a piece of 4130 chrome moly tubing from the aviation department at McMaster-Carr and cloned the Vetterman-supplied tubes. I did make a fixture similar to Sam Buchanan's, to avoid a sharp crush, which was necessary since the 4130 was so dang hard that I had to heat it in order to be able to crush the ends. In hindsight, brake line tubing like Sam used is probably plenty strong.

What ever. 900 hours and counting, including the (upgraded to some sort of fancy blue) rubber tubing, mine is still fine. In the end I probably only had an hour into making the upgraded parts. Are there better ways? Almost certainly. But with minor refinements, the Vetterman design works pretty well.
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  #27  
Old 12-03-2019, 12:44 AM
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swisseagle swisseagle is offline
 
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Quote:
Originally Posted by DanH View Post


Hey Dan ... Why not giving us some more information about?

Is it "self made" or a unit that you bought and mounted?
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  #28  
Old 12-03-2019, 06:50 AM
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DanH DanH is online now
 
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Quote:
Originally Posted by gyoung View Post
I'm not Dan but that's the same mount I received with the 4 into 1 exhaust I bought from Aerospace Welding. There's 2 SS blocks with horizontal holes welded to a plate that bolts to the fuselage. There are corresponding blocks welded to the clamp that goes around the exhaust pipe. You thread about 3 loops of SS cable on either side of the pipe to connect it to the fuselage blocks. Mine's not flying yet but it looks like the best mount I've seen.
Right...nothing custom here, just a better idea from a different pipe vendor. I've posted it in the last thirty or so "My exhaust hanger broke" threads, but apparently folks love flattened tubes and hose clamps.
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  #29  
Old 12-03-2019, 09:15 AM
Lars Lars is offline
 
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Quote:
Originally Posted by DanH View Post
Right...nothing custom here, just a better idea from a different pipe vendor. I've posted it in the last thirty or so "My exhaust hanger broke" threads, but apparently folks love flattened tubes and hose clamps.
Count me among those that think it looks hokey. Etc. But in the end (and actually, it was the beginning since my RV-7 wasn't even flying yet) all the other solutions I was dreaming up seemed too difficult to implement, especially given the space constraints with a muffler-equipped crossover system on a vertical draft engine installed in a side by side RV. And since the slight permutation I came up with (I'm not a big fan of 300 series stainless, does it show?) keeps working, I keep dreaming up other things to over-complicate
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  #30  
Old 12-03-2019, 11:06 AM
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Steve Melton Steve Melton is offline
 
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if you stay with the flattened tube you may consider 3/8 inconel 600 or 625 tubing. stronger, but not as much elongation capability when it's smashed. you may need to heat it progressive as it's smashed.
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Steve Melton
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RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 800+ for all

Simplicity is the art in design.

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