Ed,

I think the idea is you'll get a more accurate measurement at the
combustion surface of each rotor rather than measuring the temp of the
coolant that has already blended with other coolant in the system.
Its my understanding that the coolant temp will be higher around the
plug area than elsewhere, so if you operate near the boiling point of
your coolant, you would be able to tell it sooner rather than later.
Still, if you know the safe high-temp limit, it seems you would get a
better reading off the rotor housing liner than from the coolant.

If you drill/tap each rotor housing you can see how hard each rotor is
working, similar to EGT's.  CHT can serve as a cross-check to EGT.

Also, monitoring cooling system pressure should alert you to an
imminent boilover event.  But you already knew that.  ;-)


My 2 cents,
Mark

On 8/20/12, Ed Anderson <eanderson@carolina.rr.com> wrote:

I agree, Mark, that your suggestion would probably get you as close to an
equivalent CHT as we can get.

But, I'm still not understanding what that would usefully provide that is
worth more than your coolant temps.

 I presume that if for some reason the engine temperature were to rapidly
increase (perhaps due to detonation or other combustion events) that the CHT
reading would provide quicker information on the condition than would the
coolant temp so perhaps you could take corrective action before damage.
Might be a comfort factor knowing "CHT"  if using forced induction on a
rotary as things can happen pretty fast when at high boost levels.

Ed




From: Mark Steitle
Sent: Sunday, August 19, 2012 8:48 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EM2 CHT ?


Seems that this will tell you the coolant temp near the plugs, but not the
CHT.  If you want to measure the CHT, you'll need to locate a thermo-couple
down near the steel liner.  You can do this by drilling a small hole down
into the web adjacent to the leading plug, stopping at the steel liner.
Then insert a thermo-couple down into the hole so that it is touching the
steel liner.  Now you're reading the temps nearest the combustion chamber,
closest thing we have to CHT.


Mark


On Sun, Aug 19, 2012 at 10:02 AM, <hoursaway1@comcast.net> wrote:

  Sounds like a plan to me Ed, should have time Sun. to do.  David


------------------------------------------------------------------------------
  From: "Ed Anderson" <eanderson@carolina.rr.com>
  To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
  Sent: Saturday, August 18, 2012 6:54:35 AM
  Subject: [FlyRotary] Re: EM2  CHT ?


  I think I would run the engine at operational rpms (>5000) and watch the
coolant/oil temperatures - when they got to my maximum limit, I would check
the CHT reading and perhaps add 50 degrees for the limit (to start with).
If I got a lot of false alarms at that margin I would try another 50 deg.
Just a WAG.

  Ed


  From: hoursaway1@comcast.net
  Sent: Friday, August 17, 2012 10:20 PM
  To: Rotary motors in aircraft
  Subject: [FlyRotary] EM2 CHT ?


  What are we using for high temp numbers from the CHT sensors on the 13B
rotary, I have the under the spark plug style sensors bolted to each rotor
housing in some factory threaded holes just above the spark plugs, not
really the hottest spot but the holes were already in place so I KISSed it &
moved on, now I need to set my high temp warning limit & do not know what to
use.  Possibly do an eng. run with upper cowl off & check bolt/sensor temp
with a lazer temp gun at about 4000 RPM  & go another 50 deg. higher?
Ideas?  David R. Cook  RV6A Rotary





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