Yep, that's who's design I copied - I even bought my 6" inconel tube
    from
    him because he had some left over from his muffler.  The welder used
the
    inconel welding rod that I bought. So I know it was the right stuff.

    The exhaust flange joint is welded both on the outside joint and on
the
    inside joint. There is no possibility of weld failure there - the pipe
    itself would have to tear/crack.

    Like I said - Inconel doesn't live long when there is flexing. So,
maybe
    Atkins has his muffler supported and mine wasn't - although I've
    seen his a
    few times and didn't note any supports close to the can.  It does
    look like
    he has a tab for support down the line a ways - that may damp out
enough
    vibration to keep the flexing under control. For sure something was
    different!

    Joe Hull
    Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)
    Redmond (Seattle), Washington

    -----------------------------------------------------

    The exhaust always breaks just next to the weld for some strange
    reason so the flange actually supports the tube.

    Here is some more info from Marks Wrathal site on welding
    tube to exhaust flanges. Many many racers do it all the time.

    http://www.wankel.org/

    " Weld only the engine side of the flanges. Four spot wells on the
    header side seems to be the way to go. Belt sand the flange faces
    then lap them on a piece of glass and a piece of oiled wet or
    dry paper."

    "Archie backed up this crucial point as follows:"

    "In hard core racing, the same problems (as occured on N214KW)
    arose a number of years ago, mostly in funny cars, but dragsters
    also. The common denominator, other than various grades of stainless,
    was outside welds. Now you may see some tack welds on the outside,
    but the actual welding is done on the backside.(inside) Also in
    current use is a tube within a tube. I noticed the weld bead was
    quite wide, increasing the hazard, and may have contributed to the
    failure."

    Archie builds 7000 HP AA drag engines for a living and has several
    forums at OSH.

    This last trick is expensive but Everett Hatch came up with the
    idea. A ball flex joint is used right next to the block.

    Paul Lamar ...No rotor no motor.


Paul and Joe,
The more I learn about Everett Hatch the more impressed I am. The ball
joint he uses would almost double as an anti-reversion cone. Besides
relieving the pipe to block stresses note that the pipes just down
stream also have inside slip fits. Very nice work.
Bill Jepson

Anybody have a picture or schematic of Hatch's exhaust installation?

Doc


I do. Also see http://www.rotaryeng.net/exhaust.html

I just updated the exhaust system last night.
Joe's failed exhaust prompted me to do so.

-- 
Paul Lamar ...No rotor no motor.

The picture shows what appears to be a nut on a stud. I can't tell if there
is a spring under the nut or not.

The diagram on the web site shows no springs. Shouldn't the joint be spring
loaded to allow some movement and still provide a seal for the exhaust
gasses?

Doc

Correct. Belleville springs look like washers.