>      >
     >      > Hi Paul,
     >      >
     >      > I did my first taxi test last Friday.  I taxied for about 30
     >      > minutes and it didn't even get close to overheating.  Of
     > course, the
     >      > Texas summer isn't here yet, so we'll have to wait and see
     > how it
     >     does
     >      > then.  Everything worked as intended and it was great to
     >     experience my
     >      > little creation moving under its own power.  First flight is
     > still a
     >      > month or so off.
     >      >
     >      > Thanks,
     >      > Mark S
     >
     >     Mark,
     >     keep a very close eye on the exhaust pipes. looks like they are
     >     welded solid. My previous pipes were like that and most of the
     >     welds cracked in 2 hours of flying. My new setup has slip joints
     >     wherever possible, and are fine for the last 15 hrs.
     >     Buly
     >
     >     Good point Buly.
     >
     >     Paul Lamar
     >
     > Buly,
     >
     > Thanks, I appreciate your concern and will do frequent
    inspections of
     > the exhaust system.  I have almost 13 hours on this manifold and have
     > gotten it cherry red more than once.  At this point it shows no
     > signs of
     > cracking.  The 2" runs are made from .140" wall R.B. Wagner SS
     > handrails.  The outer two flange bolt holes are slotted to allow for
     > some movement due to expansion and the flange is one solid piece.
     > Welds
     > are on the engine side of the flange.  I figured that the stock
     > manifold
     > was one piece, but it did have slotted holes for expansion.  I think
     > that is what some people forget to do.  I don't tighten them very
     > tight
     > either so they can move a little if necessary.  The inside of the
    cowl
     > is covered with Fiberfrax material to protect it from radiant heat.
     > I'll have to watch it closely and see how it does.
     >
     > BTW, the homemade "spiral flow" style baffle is also holding up
    well.
     > I'll be checking that frequently as well.
     >
     > I also installed the fire detector just aft of the oil cooler,
     > "looking"
     > toward the exhaust system.  I should know immediately should the
     > exhaust
     > fail and flames start peeking through any cracks.  That UVtron
     > sensor is
     > very sensitive to flames.
     >
     > Mark S
     >

    Mark, it is a good move to go to thick wall tubes. I'm just concerned
    with the heat expansion between the tubes?
    I like your fire detector. It was amazing to watch it work at Bill's
    place. How do I get one ? :)
    Buly


Hi Buly,
I contacted the company I bought the boards from to check on a volume
purchase and they told me that they could supply more but the price
would be higher.  They said that the board I purchased was old stock
left over from a previous run.  It was a robotics supplier, but I don't
recall the name, but I can look through my files to see if I can locate
their url.  The "eye" of the unit is called a UVtron sensor.  I think it
is manufactured by a Japanese firm.  Do a Google search for that and see
what turns up.  The UVtron sensor is about $50 by itself.  I have it
hooked up to a big red LED at the top of my panel.  Hope I never see it
lit up while I'm in the air.
Mark S

I found it. Here is screen shot.
 http://www.acroname.com/robotics/parts/R67-UVTRON.html

Paul Lamar

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