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New Vetterman design exhaust mount

AlexPeterson

AlexPeterson

Well Known Member
Sorry for the poor photos, but we wanted to share a new method for attaching the tail pipes. I was speaking with Larry V. a couple weeks ago, and he mentioned that he had been flying his 7A with something like that pictured below for about 50 hours, with no problems yet. Larry was kind enough to mail me a sketch of what he was speaking about, and I instantly decided to make mine that way.

I took a 3/4" x 3/4" x 1/8" aluminum angle, and trimmed most of one leg away. The pictures tell the rest. This is elegant simplicity. The pipe can move a bit, as it needs to, because the whole thing flexes, as well as the adel clamps moving somewhat.

Unknowns include fatigue, durability, etc. What is clear to me is that some combination of material and/or design will be the ticket. Nice job Larry!

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Looks good but....

I have always been a proponent of hanging them with tubing and such from the sump so the exhaust moves with the engine. While the exhaust does have ball joints, the pipes just fair better when they swing with the engine and are not anchored at the firewall or engine mount.

I have used a similar setup to your picture with the resulting failure of the hangers and ball joints. Granted mine is a circa 1998 exhaust. The newer units Larry sells are far more mature than the oldie on my 6A.
 
Looks like more cooling exit drag............... I expect the bracket to crack at the bend.
 
I have a very similar install that now has a litttle over 150 hrs on it. My DAR was sceptical of it saying I would see cracks in the stainless clamp where the 90* bend is. So far he has been wrong. I allows you to secure the pipe as far aft as possible and actually puts less stress on the ball joint. It also eliminates the cross brace that goes from one pipe to the other that has no good way to install on A models and contribute to more exit air restriction.

Vetterman told me to put a few drops of mouse milk oil on all slips and balljoints anytime the cowl is off. Don't remember if that was in the instructions or not.
 
Hangers

I'll have to agree with Gary Zilik on the method to hang exhaust pipes....tubes to the sump and everything moves togather as a unit. What was pictured may work for a short time but it's just a matter of when it's going to crack not is it going to crack. ;) Now if you don't intend to start your engine or say never pull more than one G that method should last a longtime...... Hey Larry "what you thinking?" :D
 
Not sure I see the upside to this. Attaching a moving part to a non moving one has its downsides, mainly vibration cracking. Slip joints will not always remain free and still transmit vibration. Some rubber inserts or hangers would go a long way to assuring longer life for expensive pipes.
 
I, for one, like this idea...

Since my first flight I've been fighting with keeping the exhaust pipes from contacting either the cowling or engine mount. RV6A just doesn't have a lot of clearance.
 
I have a feiend with an RV6A that has the rubber hose and aluminum tubing exhaust hangers that attach to the rear of the sump and another hose and tubes that goes horizontal between the pipes to keep them from creeping over against the cowl. I may try that myself as I have the same problem keeping the pipes away from the cowl. Looks like a good fix.
 
And................I have a 6A, with the original plans (sonewhere around 1998) & ties to the sump............and it's been no problem. I like it that way!

L.Adamson
 
I don't see the need to change the original design. My builder tried to improve upon that design and had additional tubing/clamps that ran to the angled motor mount bar. It never worked very well in my experience and I since have reverted back to the original design.

I haven't had a problem since going back to the original. I think the exhaust needs to be able to vibrate WITH the engine and the sump is a close replica of such vibration.
 
I see a lot of merits in this approach. One issue might be some increase cockpit vibration and I wonder if there is some sort of small isolation "donut" that could be installed between the adel clamp and the angle. A bit of flexibility at that location would also address some of the other concerns. I like the simplicity of this system.
 
another method

I had a failure several times with Vans exhaust attach method where the metal tubing connects to the engine mount. One broke at the bend where the adel clamp holds it to the mount and the pipe dropped to the cowling bottom and caused a blister in the fiberglas. I used a method that worked on my /6 for over 800 hours that I "borrowed" from Cessna. It involves an adel clamp connected to a heavy duty spring at the frame and a pipe clamp on the other end of the spring holding the exhaust. To limit side to side play I installed a flat piece of 3/4 x 1/8" aluminum between the pipes at the desired distance. Now the whole unit can move on the springs and always return to it's original position. I will post some photos asap.
Woodman
 
Per plans with a slight mod...

After 100 hours or so in my -7a a couple of the tubes slipped out of the rubber hose. I disassembled them, put in a bit of a flare in the tubes (the stainless is hard, use some lube!) and reassembled them. It's a bit of a challenge to get the flared ends back into the tubing but after another several hundred hours, no shifting at all.
 
On my next oil change, I am planning on adding a small length of SS 1/16" wire/cable to the existing vertical attachment points. This way if any of the ss tubing or the rubber hose brakes or slips, the wire will hold it in place. The plane has currently 350+ hours on it and it has held up OK so far.
 
Pictures

I took a few pictures of the RV-6A that has the tubes attached to the sump and also has a crossbar tube that I am going to try on my RV9A. Looks like a pretty good solution.
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alternate method

Jim Wrights method is the way Larry V recommended when i bought my crossover for my RV8. But i did not have a straight shot from the crankcase bolts to my exhaust. So i adel clamped 4 inch pieces of 3/4 inch aluminum angle to the mount and bolted a piece of hose between the angle and the exhaust. The rubber hose was excess from the breather tube. 200 hours and all is well
 
Still no problems - but, I've had a slow couple years of flying since putting it in. I've probably only got about 140 hours on the system. I'd never go back to the old tube and hose system, that's for sure. I know Larry's system like this is still working fine, but I don't know how many hours his has. I suspect I'll hear from him shortly...
 
New Vetterman design exhaust mount.

Hi Gang, does someone have a source for the type of pipe clamp shown on the first page of this thread?

I have the new Trombone style exhaust with mufflers and the pipe clamps that came with the system have the mounting tab 90 degrees to the flow of the pipe. It's pretty busy in this area for me and if I could find the type of clamp shown earlier it would work out better.

I did not see it on Aircraft Spruce, Wicks or Summit.


Thanks in advance, Terry.
 
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